Merge tag 'hyperv-fixes-signed' of git://git.kernel.org/pub/scm/linux/kernel/git...

[mirror_ubuntu-jammy-kernel.git] / drivers / spi / spi.c

// SPDX-License-Identifier: GPL-2.0-or-later
// SPI init/core code
//
// Copyright (C) 2005 David Brownell
// Copyright (C) 2008 Secret Lab Technologies Ltd.

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/cache.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/mutex.h>
#include <linux/of_device.h>
#include <linux/of_irq.h>
#include <linux/clk/clk-conf.h>
#include <linux/slab.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi-mem.h>
#include <linux/of_gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/pm_runtime.h>
#include <linux/pm_domain.h>
#include <linux/property.h>
#include <linux/export.h>
#include <linux/sched/rt.h>
#include <uapi/linux/sched/types.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/ioport.h>
#include <linux/acpi.h>
#include <linux/highmem.h>
#include <linux/idr.h>
#include <linux/platform_data/x86/apple.h>

#define CREATE_TRACE_POINTS
#include <trace/events/spi.h>
EXPORT_TRACEPOINT_SYMBOL(spi_transfer_start);
EXPORT_TRACEPOINT_SYMBOL(spi_transfer_stop);

#include "internals.h"

static DEFINE_IDR(spi_master_idr);

static void spidev_release(struct device *dev)
{
        struct spi_device       *spi = to_spi_device(dev);

        /* spi controllers may cleanup for released devices */
        if (spi->controller->cleanup)
                spi->controller->cleanup(spi);

        spi_controller_put(spi->controller);
        kfree(spi->driver_override);
        kfree(spi);
}

static ssize_t
modalias_show(struct device *dev, struct device_attribute *a, char *buf)
{
        const struct spi_device *spi = to_spi_device(dev);
        int len;

        len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
        if (len != -ENODEV)
                return len;

        return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
}
static DEVICE_ATTR_RO(modalias);

static ssize_t driver_override_store(struct device *dev,
                                     struct device_attribute *a,
                                     const char *buf, size_t count)
{
        struct spi_device *spi = to_spi_device(dev);
        const char *end = memchr(buf, '\n', count);
        const size_t len = end ? end - buf : count;
        const char *driver_override, *old;

        /* We need to keep extra room for a newline when displaying value */
        if (len >= (PAGE_SIZE - 1))
                return -EINVAL;

        driver_override = kstrndup(buf, len, GFP_KERNEL);
        if (!driver_override)
                return -ENOMEM;

        device_lock(dev);
        old = spi->driver_override;
        if (len) {
                spi->driver_override = driver_override;
        } else {
                /* Empty string, disable driver override */
                spi->driver_override = NULL;
                kfree(driver_override);
        }
        device_unlock(dev);
        kfree(old);

        return count;
}

static ssize_t driver_override_show(struct device *dev,
                                    struct device_attribute *a, char *buf)
{
        const struct spi_device *spi = to_spi_device(dev);
        ssize_t len;

        device_lock(dev);
        len = snprintf(buf, PAGE_SIZE, "%s\n", spi->driver_override ? : "");
        device_unlock(dev);
        return len;
}
static DEVICE_ATTR_RW(driver_override);

#define SPI_STATISTICS_ATTRS(field, file)                               \
static ssize_t spi_controller_##field##_show(struct device *dev,        \
                                             struct device_attribute *attr, \
                                             char *buf)                 \
{                                                                       \
        struct spi_controller *ctlr = container_of(dev,                 \
                                         struct spi_controller, dev);   \
        return spi_statistics_##field##_show(&ctlr->statistics, buf);   \
}                                                                       \
static struct device_attribute dev_attr_spi_controller_##field = {      \
        .attr = { .name = file, .mode = 0444 },                         \
        .show = spi_controller_##field##_show,                          \
};                                                                      \
static ssize_t spi_device_##field##_show(struct device *dev,            \
                                         struct device_attribute *attr, \
                                        char *buf)                      \
{                                                                       \
        struct spi_device *spi = to_spi_device(dev);                    \
        return spi_statistics_##field##_show(&spi->statistics, buf);    \
}                                                                       \
static struct device_attribute dev_attr_spi_device_##field = {          \
        .attr = { .name = file, .mode = 0444 },                         \
        .show = spi_device_##field##_show,                              \
}

#define SPI_STATISTICS_SHOW_NAME(name, file, field, format_string)      \
static ssize_t spi_statistics_##name##_show(struct spi_statistics *stat, \
                                            char *buf)                  \
{                                                                       \
        unsigned long flags;                                            \
        ssize_t len;                                                    \
        spin_lock_irqsave(&stat->lock, flags);                          \
        len = sprintf(buf, format_string, stat->field);                 \
        spin_unlock_irqrestore(&stat->lock, flags);                     \
        return len;                                                     \
}                                                                       \
SPI_STATISTICS_ATTRS(name, file)

#define SPI_STATISTICS_SHOW(field, format_string)                       \
        SPI_STATISTICS_SHOW_NAME(field, __stringify(field),             \
                                 field, format_string)

SPI_STATISTICS_SHOW(messages, "%lu");
SPI_STATISTICS_SHOW(transfers, "%lu");
SPI_STATISTICS_SHOW(errors, "%lu");
SPI_STATISTICS_SHOW(timedout, "%lu");

SPI_STATISTICS_SHOW(spi_sync, "%lu");
SPI_STATISTICS_SHOW(spi_sync_immediate, "%lu");
SPI_STATISTICS_SHOW(spi_async, "%lu");

SPI_STATISTICS_SHOW(bytes, "%llu");
SPI_STATISTICS_SHOW(bytes_rx, "%llu");
SPI_STATISTICS_SHOW(bytes_tx, "%llu");

#define SPI_STATISTICS_TRANSFER_BYTES_HISTO(index, number)              \
        SPI_STATISTICS_SHOW_NAME(transfer_bytes_histo##index,           \
                                 "transfer_bytes_histo_" number,        \
                                 transfer_bytes_histo[index],  "%lu")
SPI_STATISTICS_TRANSFER_BYTES_HISTO(0,  "0-1");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(1,  "2-3");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(2,  "4-7");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(3,  "8-15");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(4,  "16-31");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(5,  "32-63");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(6,  "64-127");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(7,  "128-255");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(8,  "256-511");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(9,  "512-1023");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(10, "1024-2047");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(11, "2048-4095");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(12, "4096-8191");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(13, "8192-16383");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+");

SPI_STATISTICS_SHOW(transfers_split_maxsize, "%lu");

static struct attribute *spi_dev_attrs[] = {
        &dev_attr_modalias.attr,
        &dev_attr_driver_override.attr,
        NULL,
};

static const struct attribute_group spi_dev_group = {
        .attrs  = spi_dev_attrs,
};

static struct attribute *spi_device_statistics_attrs[] = {
        &dev_attr_spi_device_messages.attr,
        &dev_attr_spi_device_transfers.attr,
        &dev_attr_spi_device_errors.attr,
        &dev_attr_spi_device_timedout.attr,
        &dev_attr_spi_device_spi_sync.attr,
        &dev_attr_spi_device_spi_sync_immediate.attr,
        &dev_attr_spi_device_spi_async.attr,
        &dev_attr_spi_device_bytes.attr,
        &dev_attr_spi_device_bytes_rx.attr,
        &dev_attr_spi_device_bytes_tx.attr,
        &dev_attr_spi_device_transfer_bytes_histo0.attr,
        &dev_attr_spi_device_transfer_bytes_histo1.attr,
        &dev_attr_spi_device_transfer_bytes_histo2.attr,
        &dev_attr_spi_device_transfer_bytes_histo3.attr,
        &dev_attr_spi_device_transfer_bytes_histo4.attr,
        &dev_attr_spi_device_transfer_bytes_histo5.attr,
        &dev_attr_spi_device_transfer_bytes_histo6.attr,
        &dev_attr_spi_device_transfer_bytes_histo7.attr,
        &dev_attr_spi_device_transfer_bytes_histo8.attr,
        &dev_attr_spi_device_transfer_bytes_histo9.attr,
        &dev_attr_spi_device_transfer_bytes_histo10.attr,
        &dev_attr_spi_device_transfer_bytes_histo11.attr,
        &dev_attr_spi_device_transfer_bytes_histo12.attr,
        &dev_attr_spi_device_transfer_bytes_histo13.attr,
        &dev_attr_spi_device_transfer_bytes_histo14.attr,
        &dev_attr_spi_device_transfer_bytes_histo15.attr,
        &dev_attr_spi_device_transfer_bytes_histo16.attr,
        &dev_attr_spi_device_transfers_split_maxsize.attr,
        NULL,
};

static const struct attribute_group spi_device_statistics_group = {
        .name  = "statistics",
        .attrs  = spi_device_statistics_attrs,
};

static const struct attribute_group *spi_dev_groups[] = {
        &spi_dev_group,
        &spi_device_statistics_group,
        NULL,
};

static struct attribute *spi_controller_statistics_attrs[] = {
        &dev_attr_spi_controller_messages.attr,
        &dev_attr_spi_controller_transfers.attr,
        &dev_attr_spi_controller_errors.attr,
        &dev_attr_spi_controller_timedout.attr,
        &dev_attr_spi_controller_spi_sync.attr,
        &dev_attr_spi_controller_spi_sync_immediate.attr,
        &dev_attr_spi_controller_spi_async.attr,
        &dev_attr_spi_controller_bytes.attr,
        &dev_attr_spi_controller_bytes_rx.attr,
        &dev_attr_spi_controller_bytes_tx.attr,
        &dev_attr_spi_controller_transfer_bytes_histo0.attr,
        &dev_attr_spi_controller_transfer_bytes_histo1.attr,
        &dev_attr_spi_controller_transfer_bytes_histo2.attr,
        &dev_attr_spi_controller_transfer_bytes_histo3.attr,
        &dev_attr_spi_controller_transfer_bytes_histo4.attr,
        &dev_attr_spi_controller_transfer_bytes_histo5.attr,
        &dev_attr_spi_controller_transfer_bytes_histo6.attr,
        &dev_attr_spi_controller_transfer_bytes_histo7.attr,
        &dev_attr_spi_controller_transfer_bytes_histo8.attr,
        &dev_attr_spi_controller_transfer_bytes_histo9.attr,
        &dev_attr_spi_controller_transfer_bytes_histo10.attr,
        &dev_attr_spi_controller_transfer_bytes_histo11.attr,
        &dev_attr_spi_controller_transfer_bytes_histo12.attr,
        &dev_attr_spi_controller_transfer_bytes_histo13.attr,
        &dev_attr_spi_controller_transfer_bytes_histo14.attr,
        &dev_attr_spi_controller_transfer_bytes_histo15.attr,
        &dev_attr_spi_controller_transfer_bytes_histo16.attr,
        &dev_attr_spi_controller_transfers_split_maxsize.attr,
        NULL,
};

static const struct attribute_group spi_controller_statistics_group = {
        .name  = "statistics",
        .attrs  = spi_controller_statistics_attrs,
};

static const struct attribute_group *spi_master_groups[] = {
        &spi_controller_statistics_group,
        NULL,
};

void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
                                       struct spi_transfer *xfer,
                                       struct spi_controller *ctlr)
{
        unsigned long flags;
        int l2len = min(fls(xfer->len), SPI_STATISTICS_HISTO_SIZE) - 1;

        if (l2len < 0)
                l2len = 0;

        spin_lock_irqsave(&stats->lock, flags);

        stats->transfers++;
        stats->transfer_bytes_histo[l2len]++;

        stats->bytes += xfer->len;
        if ((xfer->tx_buf) &&
            (xfer->tx_buf != ctlr->dummy_tx))
                stats->bytes_tx += xfer->len;
        if ((xfer->rx_buf) &&
            (xfer->rx_buf != ctlr->dummy_rx))
                stats->bytes_rx += xfer->len;

        spin_unlock_irqrestore(&stats->lock, flags);
}
EXPORT_SYMBOL_GPL(spi_statistics_add_transfer_stats);

/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
 * and the sysfs version makes coldplug work too.
 */

static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
                                                const struct spi_device *sdev)
{
        while (id->name[0]) {
                if (!strcmp(sdev->modalias, id->name))
                        return id;
                id++;
        }
        return NULL;
}

const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
{
        const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);

        return spi_match_id(sdrv->id_table, sdev);
}
EXPORT_SYMBOL_GPL(spi_get_device_id);

static int spi_match_device(struct device *dev, struct device_driver *drv)
{
        const struct spi_device *spi = to_spi_device(dev);
        const struct spi_driver *sdrv = to_spi_driver(drv);

        /* Check override first, and if set, only use the named driver */
        if (spi->driver_override)
                return strcmp(spi->driver_override, drv->name) == 0;

        /* Attempt an OF style match */
        if (of_driver_match_device(dev, drv))
                return 1;

        /* Then try ACPI */
        if (acpi_driver_match_device(dev, drv))
                return 1;

        if (sdrv->id_table)
                return !!spi_match_id(sdrv->id_table, spi);

        return strcmp(spi->modalias, drv->name) == 0;
}

static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        const struct spi_device         *spi = to_spi_device(dev);
        int rc;

        rc = acpi_device_uevent_modalias(dev, env);
        if (rc != -ENODEV)
                return rc;

        return add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
}

struct bus_type spi_bus_type = {
        .name           = "spi",
        .dev_groups     = spi_dev_groups,
        .match          = spi_match_device,
        .uevent         = spi_uevent,
};
EXPORT_SYMBOL_GPL(spi_bus_type);


static int spi_drv_probe(struct device *dev)
{
        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
        struct spi_device               *spi = to_spi_device(dev);
        int ret;

        ret = of_clk_set_defaults(dev->of_node, false);
        if (ret)
                return ret;

        if (dev->of_node) {
                spi->irq = of_irq_get(dev->of_node, 0);
                if (spi->irq == -EPROBE_DEFER)
                        return -EPROBE_DEFER;
                if (spi->irq < 0)
                        spi->irq = 0;
        }

        ret = dev_pm_domain_attach(dev, true);
        if (ret)
                return ret;

        ret = sdrv->probe(spi);
        if (ret)
                dev_pm_domain_detach(dev, true);

        return ret;
}

static int spi_drv_remove(struct device *dev)
{
        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
        int ret;

        ret = sdrv->remove(to_spi_device(dev));
        dev_pm_domain_detach(dev, true);

        return ret;
}

static void spi_drv_shutdown(struct device *dev)
{
        const struct spi_driver         *sdrv = to_spi_driver(dev->driver);

        sdrv->shutdown(to_spi_device(dev));
}

/**
 * __spi_register_driver - register a SPI driver
 * @owner: owner module of the driver to register
 * @sdrv: the driver to register
 * Context: can sleep
 *
 * Return: zero on success, else a negative error code.
 */
int __spi_register_driver(struct module *owner, struct spi_driver *sdrv)
{
        sdrv->driver.owner = owner;
        sdrv->driver.bus = &spi_bus_type;
        if (sdrv->probe)
                sdrv->driver.probe = spi_drv_probe;
        if (sdrv->remove)
                sdrv->driver.remove = spi_drv_remove;
        if (sdrv->shutdown)
                sdrv->driver.shutdown = spi_drv_shutdown;
        return driver_register(&sdrv->driver);
}
EXPORT_SYMBOL_GPL(__spi_register_driver);

/*-------------------------------------------------------------------------*/

/* SPI devices should normally not be created by SPI device drivers; that
 * would make them board-specific.  Similarly with SPI controller drivers.
 * Device registration normally goes into like arch/.../mach.../board-YYY.c
 * with other readonly (flashable) information about mainboard devices.
 */

struct boardinfo {
        struct list_head        list;
        struct spi_board_info   board_info;
};

static LIST_HEAD(board_list);
static LIST_HEAD(spi_controller_list);

/*
 * Used to protect add/del operation for board_info list and
 * spi_controller list, and their matching process
 * also used to protect object of type struct idr
 */
static DEFINE_MUTEX(board_lock);

/*
 * Prevents addition of devices with same chip select and
 * addition of devices below an unregistering controller.
 */
static DEFINE_MUTEX(spi_add_lock);

/**
 * spi_alloc_device - Allocate a new SPI device
 * @ctlr: Controller to which device is connected
 * Context: can sleep
 *
 * Allows a driver to allocate and initialize a spi_device without
 * registering it immediately.  This allows a driver to directly
 * fill the spi_device with device parameters before calling
 * spi_add_device() on it.
 *
 * Caller is responsible to call spi_add_device() on the returned
 * spi_device structure to add it to the SPI controller.  If the caller
 * needs to discard the spi_device without adding it, then it should
 * call spi_dev_put() on it.
 *
 * Return: a pointer to the new device, or NULL.
 */
struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
{
        struct spi_device       *spi;

        if (!spi_controller_get(ctlr))
                return NULL;

        spi = kzalloc(sizeof(*spi), GFP_KERNEL);
        if (!spi) {
                spi_controller_put(ctlr);
                return NULL;
        }

        spi->master = spi->controller = ctlr;
        spi->dev.parent = &ctlr->dev;
        spi->dev.bus = &spi_bus_type;
        spi->dev.release = spidev_release;
        spi->cs_gpio = -ENOENT;
        spi->mode = ctlr->buswidth_override_bits;

        spin_lock_init(&spi->statistics.lock);

        device_initialize(&spi->dev);
        return spi;
}
EXPORT_SYMBOL_GPL(spi_alloc_device);

static void spi_dev_set_name(struct spi_device *spi)
{
        struct acpi_device *adev = ACPI_COMPANION(&spi->dev);

        if (adev) {
                dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
                return;
        }

        dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->controller->dev),
                     spi->chip_select);
}

static int spi_dev_check(struct device *dev, void *data)
{
        struct spi_device *spi = to_spi_device(dev);
        struct spi_device *new_spi = data;

        if (spi->controller == new_spi->controller &&
            spi->chip_select == new_spi->chip_select)
                return -EBUSY;
        return 0;
}

/**
 * spi_add_device - Add spi_device allocated with spi_alloc_device
 * @spi: spi_device to register
 *
 * Companion function to spi_alloc_device.  Devices allocated with
 * spi_alloc_device can be added onto the spi bus with this function.
 *
 * Return: 0 on success; negative errno on failure
 */
int spi_add_device(struct spi_device *spi)
{
        struct spi_controller *ctlr = spi->controller;
        struct device *dev = ctlr->dev.parent;
        int status;

        /* Chipselects are numbered 0..max; validate. */
        if (spi->chip_select >= ctlr->num_chipselect) {
                dev_err(dev, "cs%d >= max %d\n", spi->chip_select,
                        ctlr->num_chipselect);
                return -EINVAL;
        }

        /* Set the bus ID string */
        spi_dev_set_name(spi);

        /* We need to make sure there's no other device with this
         * chipselect **BEFORE** we call setup(), else we'll trash
         * its configuration.  Lock against concurrent add() calls.
         */
        mutex_lock(&spi_add_lock);

        status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
        if (status) {
                dev_err(dev, "chipselect %d already in use\n",
                                spi->chip_select);
                goto done;
        }

        /* Controller may unregister concurrently */
        if (IS_ENABLED(CONFIG_SPI_DYNAMIC) &&
            !device_is_registered(&ctlr->dev)) {
                status = -ENODEV;
                goto done;
        }

        /* Descriptors take precedence */
        if (ctlr->cs_gpiods)
                spi->cs_gpiod = ctlr->cs_gpiods[spi->chip_select];
        else if (ctlr->cs_gpios)
                spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];

        /* Drivers may modify this initial i/o setup, but will
         * normally rely on the device being setup.  Devices
         * using SPI_CS_HIGH can't coexist well otherwise...
         */
        status = spi_setup(spi);
        if (status < 0) {
                dev_err(dev, "can't setup %s, status %d\n",
                                dev_name(&spi->dev), status);
                goto done;
        }

        /* Device may be bound to an active driver when this returns */
        status = device_add(&spi->dev);
        if (status < 0)
                dev_err(dev, "can't add %s, status %d\n",
                                dev_name(&spi->dev), status);
        else
                dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));

done:
        mutex_unlock(&spi_add_lock);
        return status;
}
EXPORT_SYMBOL_GPL(spi_add_device);

/**
 * spi_new_device - instantiate one new SPI device
 * @ctlr: Controller to which device is connected
 * @chip: Describes the SPI device
 * Context: can sleep
 *
 * On typical mainboards, this is purely internal; and it's not needed
 * after board init creates the hard-wired devices.  Some development
 * platforms may not be able to use spi_register_board_info though, and
 * this is exported so that for example a USB or parport based adapter
 * driver could add devices (which it would learn about out-of-band).
 *
 * Return: the new device, or NULL.
 */
struct spi_device *spi_new_device(struct spi_controller *ctlr,
                                  struct spi_board_info *chip)
{
        struct spi_device       *proxy;
        int                     status;

        /* NOTE:  caller did any chip->bus_num checks necessary.
         *
         * Also, unless we change the return value convention to use
         * error-or-pointer (not NULL-or-pointer), troubleshootability
         * suggests syslogged diagnostics are best here (ugh).
         */

        proxy = spi_alloc_device(ctlr);
        if (!proxy)
                return NULL;

        WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));

        proxy->chip_select = chip->chip_select;
        proxy->max_speed_hz = chip->max_speed_hz;
        proxy->mode = chip->mode;
        proxy->irq = chip->irq;
        strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
        proxy->dev.platform_data = (void *) chip->platform_data;
        proxy->controller_data = chip->controller_data;
        proxy->controller_state = NULL;

        if (chip->properties) {
                status = device_add_properties(&proxy->dev, chip->properties);
                if (status) {
                        dev_err(&ctlr->dev,
                                "failed to add properties to '%s': %d\n",
                                chip->modalias, status);
                        goto err_dev_put;
                }
        }

        status = spi_add_device(proxy);
        if (status < 0)
                goto err_remove_props;

        return proxy;

err_remove_props:
        if (chip->properties)
                device_remove_properties(&proxy->dev);
err_dev_put:
        spi_dev_put(proxy);
        return NULL;
}
EXPORT_SYMBOL_GPL(spi_new_device);

/**
 * spi_unregister_device - unregister a single SPI device
 * @spi: spi_device to unregister
 *
 * Start making the passed SPI device vanish. Normally this would be handled
 * by spi_unregister_controller().
 */
void spi_unregister_device(struct spi_device *spi)
{
        if (!spi)
                return;

        if (spi->dev.of_node) {
                of_node_clear_flag(spi->dev.of_node, OF_POPULATED);
                of_node_put(spi->dev.of_node);
        }
        if (ACPI_COMPANION(&spi->dev))
                acpi_device_clear_enumerated(ACPI_COMPANION(&spi->dev));
        device_unregister(&spi->dev);
}
EXPORT_SYMBOL_GPL(spi_unregister_device);

static void spi_match_controller_to_boardinfo(struct spi_controller *ctlr,
                                              struct spi_board_info *bi)
{
        struct spi_device *dev;

        if (ctlr->bus_num != bi->bus_num)
                return;

        dev = spi_new_device(ctlr, bi);
        if (!dev)
                dev_err(ctlr->dev.parent, "can't create new device for %s\n",
                        bi->modalias);
}

/**
 * spi_register_board_info - register SPI devices for a given board
 * @info: array of chip descriptors
 * @n: how many descriptors are provided
 * Context: can sleep
 *
 * Board-specific early init code calls this (probably during arch_initcall)
 * with segments of the SPI device table.  Any device nodes are created later,
 * after the relevant parent SPI controller (bus_num) is defined.  We keep
 * this table of devices forever, so that reloading a controller driver will
 * not make Linux forget about these hard-wired devices.
 *
 * Other code can also call this, e.g. a particular add-on board might provide
 * SPI devices through its expansion connector, so code initializing that board
 * would naturally declare its SPI devices.
 *
 * The board info passed can safely be __initdata ... but be careful of
 * any embedded pointers (platform_data, etc), they're copied as-is.
 * Device properties are deep-copied though.
 *
 * Return: zero on success, else a negative error code.
 */
int spi_register_board_info(struct spi_board_info const *info, unsigned n)
{
        struct boardinfo *bi;
        int i;

        if (!n)
                return 0;

        bi = kcalloc(n, sizeof(*bi), GFP_KERNEL);
        if (!bi)
                return -ENOMEM;

        for (i = 0; i < n; i++, bi++, info++) {
                struct spi_controller *ctlr;

                memcpy(&bi->board_info, info, sizeof(*info));
                if (info->properties) {
                        bi->board_info.properties =
                                        property_entries_dup(info->properties);
                        if (IS_ERR(bi->board_info.properties))
                                return PTR_ERR(bi->board_info.properties);
                }

                mutex_lock(&board_lock);
                list_add_tail(&bi->list, &board_list);
                list_for_each_entry(ctlr, &spi_controller_list, list)
                        spi_match_controller_to_boardinfo(ctlr,
                                                          &bi->board_info);
                mutex_unlock(&board_lock);
        }

        return 0;
}

/*-------------------------------------------------------------------------*/

static void spi_set_cs(struct spi_device *spi, bool enable)
{
        bool enable1 = enable;

        /*
         * Avoid calling into the driver (or doing delays) if the chip select
         * isn't actually changing from the last time this was called.
         */
        if ((spi->controller->last_cs_enable == enable) &&
            (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH)))
                return;

        spi->controller->last_cs_enable = enable;
        spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH;

        if (!spi->controller->set_cs_timing) {
                if (enable1)
                        spi_delay_exec(&spi->controller->cs_setup, NULL);
                else
                        spi_delay_exec(&spi->controller->cs_hold, NULL);
        }

        if (spi->mode & SPI_CS_HIGH)
                enable = !enable;

        if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) {
                if (!(spi->mode & SPI_NO_CS)) {
                        if (spi->cs_gpiod)
                                /* polarity handled by gpiolib */
                                gpiod_set_value_cansleep(spi->cs_gpiod,
                                                         enable1);
                        else
                                /*
                                 * invert the enable line, as active low is
                                 * default for SPI.
                                 */
                                gpio_set_value_cansleep(spi->cs_gpio, !enable);
                }
                /* Some SPI masters need both GPIO CS & slave_select */
                if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
                    spi->controller->set_cs)
                        spi->controller->set_cs(spi, !enable);
        } else if (spi->controller->set_cs) {
                spi->controller->set_cs(spi, !enable);
        }

        if (!spi->controller->set_cs_timing) {
                if (!enable1)
                        spi_delay_exec(&spi->controller->cs_inactive, NULL);
        }
}

#ifdef CONFIG_HAS_DMA
int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
                struct sg_table *sgt, void *buf, size_t len,
                enum dma_data_direction dir)
{
        const bool vmalloced_buf = is_vmalloc_addr(buf);
        unsigned int max_seg_size = dma_get_max_seg_size(dev);
#ifdef CONFIG_HIGHMEM
        const bool kmap_buf = ((unsigned long)buf >= PKMAP_BASE &&
                                (unsigned long)buf < (PKMAP_BASE +
                                        (LAST_PKMAP * PAGE_SIZE)));
#else
        const bool kmap_buf = false;
#endif
        int desc_len;
        int sgs;
        struct page *vm_page;
        struct scatterlist *sg;
        void *sg_buf;
        size_t min;
        int i, ret;

        if (vmalloced_buf || kmap_buf) {
                desc_len = min_t(int, max_seg_size, PAGE_SIZE);
                sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
        } else if (virt_addr_valid(buf)) {
                desc_len = min_t(int, max_seg_size, ctlr->max_dma_len);
                sgs = DIV_ROUND_UP(len, desc_len);
        } else {
                return -EINVAL;
        }

        ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
        if (ret != 0)
                return ret;

        sg = &sgt->sgl[0];
        for (i = 0; i < sgs; i++) {

                if (vmalloced_buf || kmap_buf) {
                        /*
                         * Next scatterlist entry size is the minimum between
                         * the desc_len and the remaining buffer length that
                         * fits in a page.
                         */
                        min = min_t(size_t, desc_len,
                                    min_t(size_t, len,
                                          PAGE_SIZE - offset_in_page(buf)));
                        if (vmalloced_buf)
                                vm_page = vmalloc_to_page(buf);
                        else
                                vm_page = kmap_to_page(buf);
                        if (!vm_page) {
                                sg_free_table(sgt);
                                return -ENOMEM;
                        }
                        sg_set_page(sg, vm_page,
                                    min, offset_in_page(buf));
                } else {
                        min = min_t(size_t, len, desc_len);
                        sg_buf = buf;
                        sg_set_buf(sg, sg_buf, min);
                }

                buf += min;
                len -= min;
                sg = sg_next(sg);
        }

        ret = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
        if (!ret)
                ret = -ENOMEM;
        if (ret < 0) {
                sg_free_table(sgt);
                return ret;
        }

        sgt->nents = ret;

        return 0;
}

void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
                   struct sg_table *sgt, enum dma_data_direction dir)
{
        if (sgt->orig_nents) {
                dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
                sg_free_table(sgt);
        }
}

static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
{
        struct device *tx_dev, *rx_dev;
        struct spi_transfer *xfer;
        int ret;

        if (!ctlr->can_dma)
                return 0;

        if (ctlr->dma_tx)
                tx_dev = ctlr->dma_tx->device->dev;
        else
                tx_dev = ctlr->dev.parent;

        if (ctlr->dma_rx)
                rx_dev = ctlr->dma_rx->device->dev;
        else
                rx_dev = ctlr->dev.parent;

        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                if (!ctlr->can_dma(ctlr, msg->spi, xfer))
                        continue;

                if (xfer->tx_buf != NULL) {
                        ret = spi_map_buf(ctlr, tx_dev, &xfer->tx_sg,
                                          (void *)xfer->tx_buf, xfer->len,
                                          DMA_TO_DEVICE);
                        if (ret != 0)
                                return ret;
                }

                if (xfer->rx_buf != NULL) {
                        ret = spi_map_buf(ctlr, rx_dev, &xfer->rx_sg,
                                          xfer->rx_buf, xfer->len,
                                          DMA_FROM_DEVICE);
                        if (ret != 0) {
                                spi_unmap_buf(ctlr, tx_dev, &xfer->tx_sg,
                                              DMA_TO_DEVICE);
                                return ret;
                        }
                }
        }

        ctlr->cur_msg_mapped = true;

        return 0;
}

static int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg)
{
        struct spi_transfer *xfer;
        struct device *tx_dev, *rx_dev;

        if (!ctlr->cur_msg_mapped || !ctlr->can_dma)
                return 0;

        if (ctlr->dma_tx)
                tx_dev = ctlr->dma_tx->device->dev;
        else
                tx_dev = ctlr->dev.parent;

        if (ctlr->dma_rx)
                rx_dev = ctlr->dma_rx->device->dev;
        else
                rx_dev = ctlr->dev.parent;

        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                if (!ctlr->can_dma(ctlr, msg->spi, xfer))
                        continue;

                spi_unmap_buf(ctlr, rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
                spi_unmap_buf(ctlr, tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
        }

        ctlr->cur_msg_mapped = false;

        return 0;
}
#else /* !CONFIG_HAS_DMA */
static inline int __spi_map_msg(struct spi_controller *ctlr,
                                struct spi_message *msg)
{
        return 0;
}

static inline int __spi_unmap_msg(struct spi_controller *ctlr,
                                  struct spi_message *msg)
{
        return 0;
}
#endif /* !CONFIG_HAS_DMA */

static inline int spi_unmap_msg(struct spi_controller *ctlr,
                                struct spi_message *msg)
{
        struct spi_transfer *xfer;

        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                /*
                 * Restore the original value of tx_buf or rx_buf if they are
                 * NULL.
                 */
                if (xfer->tx_buf == ctlr->dummy_tx)
                        xfer->tx_buf = NULL;
                if (xfer->rx_buf == ctlr->dummy_rx)
                        xfer->rx_buf = NULL;
        }

        return __spi_unmap_msg(ctlr, msg);
}

static int spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
{
        struct spi_transfer *xfer;
        void *tmp;
        unsigned int max_tx, max_rx;

        if ((ctlr->flags & (SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX))
                && !(msg->spi->mode & SPI_3WIRE)) {
                max_tx = 0;
                max_rx = 0;

                list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                        if ((ctlr->flags & SPI_CONTROLLER_MUST_TX) &&
                            !xfer->tx_buf)
                                max_tx = max(xfer->len, max_tx);
                        if ((ctlr->flags & SPI_CONTROLLER_MUST_RX) &&
                            !xfer->rx_buf)
                                max_rx = max(xfer->len, max_rx);
                }

                if (max_tx) {
                        tmp = krealloc(ctlr->dummy_tx, max_tx,
                                       GFP_KERNEL | GFP_DMA);
                        if (!tmp)
                                return -ENOMEM;
                        ctlr->dummy_tx = tmp;
                        memset(tmp, 0, max_tx);
                }

                if (max_rx) {
                        tmp = krealloc(ctlr->dummy_rx, max_rx,
                                       GFP_KERNEL | GFP_DMA);
                        if (!tmp)
                                return -ENOMEM;
                        ctlr->dummy_rx = tmp;
                }

                if (max_tx || max_rx) {
                        list_for_each_entry(xfer, &msg->transfers,
                                            transfer_list) {
                                if (!xfer->len)
                                        continue;
                                if (!xfer->tx_buf)
                                        xfer->tx_buf = ctlr->dummy_tx;
                                if (!xfer->rx_buf)
                                        xfer->rx_buf = ctlr->dummy_rx;
                        }
                }
        }

        return __spi_map_msg(ctlr, msg);
}

static int spi_transfer_wait(struct spi_controller *ctlr,
                             struct spi_message *msg,
                             struct spi_transfer *xfer)
{
        struct spi_statistics *statm = &ctlr->statistics;
        struct spi_statistics *stats = &msg->spi->statistics;
        unsigned long long ms;

        if (spi_controller_is_slave(ctlr)) {
                if (wait_for_completion_interruptible(&ctlr->xfer_completion)) {
                        dev_dbg(&msg->spi->dev, "SPI transfer interrupted\n");
                        return -EINTR;
                }
        } else {
                ms = 8LL * 1000LL * xfer->len;
                do_div(ms, xfer->speed_hz);
                ms += ms + 200; /* some tolerance */

                if (ms > UINT_MAX)
                        ms = UINT_MAX;

                ms = wait_for_completion_timeout(&ctlr->xfer_completion,
                                                 msecs_to_jiffies(ms));

                if (ms == 0) {
                        SPI_STATISTICS_INCREMENT_FIELD(statm, timedout);
                        SPI_STATISTICS_INCREMENT_FIELD(stats, timedout);
                        dev_err(&msg->spi->dev,
                                "SPI transfer timed out\n");
                        return -ETIMEDOUT;
                }
        }

        return 0;
}

static void _spi_transfer_delay_ns(u32 ns)
{
        if (!ns)
                return;
        if (ns <= 1000) {
                ndelay(ns);
        } else {
                u32 us = DIV_ROUND_UP(ns, 1000);

                if (us <= 10)
                        udelay(us);
                else
                        usleep_range(us, us + DIV_ROUND_UP(us, 10));
        }
}

int spi_delay_to_ns(struct spi_delay *_delay, struct spi_transfer *xfer)
{
        u32 delay = _delay->value;
        u32 unit = _delay->unit;
        u32 hz;

        if (!delay)
                return 0;

        switch (unit) {
        case SPI_DELAY_UNIT_USECS:
                delay *= 1000;
                break;
        case SPI_DELAY_UNIT_NSECS: /* nothing to do here */
                break;
        case SPI_DELAY_UNIT_SCK:
                /* clock cycles need to be obtained from spi_transfer */
                if (!xfer)
                        return -EINVAL;
                /* if there is no effective speed know, then approximate
                 * by underestimating with half the requested hz
                 */
                hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2;
                if (!hz)
                        return -EINVAL;
                delay *= DIV_ROUND_UP(1000000000, hz);
                break;
        default:
                return -EINVAL;
        }

        return delay;
}
EXPORT_SYMBOL_GPL(spi_delay_to_ns);

int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer)
{
        int delay;

        might_sleep();

        if (!_delay)
                return -EINVAL;

        delay = spi_delay_to_ns(_delay, xfer);
        if (delay < 0)
                return delay;

        _spi_transfer_delay_ns(delay);

        return 0;
}
EXPORT_SYMBOL_GPL(spi_delay_exec);

static void _spi_transfer_cs_change_delay(struct spi_message *msg,
                                          struct spi_transfer *xfer)
{
        u32 delay = xfer->cs_change_delay.value;
        u32 unit = xfer->cs_change_delay.unit;
        int ret;

        /* return early on "fast" mode - for everything but USECS */
        if (!delay) {
                if (unit == SPI_DELAY_UNIT_USECS)
                        _spi_transfer_delay_ns(10000);
                return;
        }

        ret = spi_delay_exec(&xfer->cs_change_delay, xfer);
        if (ret) {
                dev_err_once(&msg->spi->dev,
                             "Use of unsupported delay unit %i, using default of 10us\n",
                             unit);
                _spi_transfer_delay_ns(10000);
        }
}

/*
 * spi_transfer_one_message - Default implementation of transfer_one_message()
 *
 * This is a standard implementation of transfer_one_message() for
 * drivers which implement a transfer_one() operation.  It provides
 * standard handling of delays and chip select management.
 */
static int spi_transfer_one_message(struct spi_controller *ctlr,
                                    struct spi_message *msg)
{
        struct spi_transfer *xfer;
        bool keep_cs = false;
        int ret = 0;
        struct spi_statistics *statm = &ctlr->statistics;
        struct spi_statistics *stats = &msg->spi->statistics;

        spi_set_cs(msg->spi, true);

        SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
        SPI_STATISTICS_INCREMENT_FIELD(stats, messages);

        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                trace_spi_transfer_start(msg, xfer);

                spi_statistics_add_transfer_stats(statm, xfer, ctlr);
                spi_statistics_add_transfer_stats(stats, xfer, ctlr);

                if (!ctlr->ptp_sts_supported) {
                        xfer->ptp_sts_word_pre = 0;
                        ptp_read_system_prets(xfer->ptp_sts);
                }

                if (xfer->tx_buf || xfer->rx_buf) {
                        reinit_completion(&ctlr->xfer_completion);

fallback_pio:
                        ret = ctlr->transfer_one(ctlr, msg->spi, xfer);
                        if (ret < 0) {
                                if (ctlr->cur_msg_mapped &&
                                   (xfer->error & SPI_TRANS_FAIL_NO_START)) {
                                        __spi_unmap_msg(ctlr, msg);
                                        ctlr->fallback = true;
                                        xfer->error &= ~SPI_TRANS_FAIL_NO_START;
                                        goto fallback_pio;
                                }

                                SPI_STATISTICS_INCREMENT_FIELD(statm,
                                                               errors);
                                SPI_STATISTICS_INCREMENT_FIELD(stats,
                                                               errors);
                                dev_err(&msg->spi->dev,
                                        "SPI transfer failed: %d\n", ret);
                                goto out;
                        }

                        if (ret > 0) {
                                ret = spi_transfer_wait(ctlr, msg, xfer);
                                if (ret < 0)
                                        msg->status = ret;
                        }
                } else {
                        if (xfer->len)
                                dev_err(&msg->spi->dev,
                                        "Bufferless transfer has length %u\n",
                                        xfer->len);
                }

                if (!ctlr->ptp_sts_supported) {
                        ptp_read_system_postts(xfer->ptp_sts);
                        xfer->ptp_sts_word_post = xfer->len;
                }

                trace_spi_transfer_stop(msg, xfer);

                if (msg->status != -EINPROGRESS)
                        goto out;

                spi_transfer_delay_exec(xfer);

                if (xfer->cs_change) {
                        if (list_is_last(&xfer->transfer_list,
                                         &msg->transfers)) {
                                keep_cs = true;
                        } else {
                                spi_set_cs(msg->spi, false);
                                _spi_transfer_cs_change_delay(msg, xfer);
                                spi_set_cs(msg->spi, true);
                        }
                }

                msg->actual_length += xfer->len;
        }

out:
        if (ret != 0 || !keep_cs)
                spi_set_cs(msg->spi, false);

        if (msg->status == -EINPROGRESS)
                msg->status = ret;

        if (msg->status && ctlr->handle_err)
                ctlr->handle_err(ctlr, msg);

        spi_finalize_current_message(ctlr);

        return ret;
}

/**
 * spi_finalize_current_transfer - report completion of a transfer
 * @ctlr: the controller reporting completion
 *
 * Called by SPI drivers using the core transfer_one_message()
 * implementation to notify it that the current interrupt driven
 * transfer has finished and the next one may be scheduled.
 */
void spi_finalize_current_transfer(struct spi_controller *ctlr)
{
        complete(&ctlr->xfer_completion);
}
EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);

static void spi_idle_runtime_pm(struct spi_controller *ctlr)
{
        if (ctlr->auto_runtime_pm) {
                pm_runtime_mark_last_busy(ctlr->dev.parent);
                pm_runtime_put_autosuspend(ctlr->dev.parent);
        }
}

/**
 * __spi_pump_messages - function which processes spi message queue
 * @ctlr: controller to process queue for
 * @in_kthread: true if we are in the context of the message pump thread
 *
 * This function checks if there is any spi message in the queue that
 * needs processing and if so call out to the driver to initialize hardware
 * and transfer each message.
 *
 * Note that it is called both from the kthread itself and also from
 * inside spi_sync(); the queue extraction handling at the top of the
 * function should deal with this safely.
 */
static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
{
        struct spi_transfer *xfer;
        struct spi_message *msg;
        bool was_busy = false;
        unsigned long flags;
        int ret;

        /* Lock queue */
        spin_lock_irqsave(&ctlr->queue_lock, flags);

        /* Make sure we are not already running a message */
        if (ctlr->cur_msg) {
                spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                return;
        }

        /* If another context is idling the device then defer */
        if (ctlr->idling) {
                kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
                spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                return;
        }

        /* Check if the queue is idle */
        if (list_empty(&ctlr->queue) || !ctlr->running) {
                if (!ctlr->busy) {
                        spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                        return;
                }

                /* Defer any non-atomic teardown to the thread */
                if (!in_kthread) {
                        if (!ctlr->dummy_rx && !ctlr->dummy_tx &&
                            !ctlr->unprepare_transfer_hardware) {
                                spi_idle_runtime_pm(ctlr);
                                ctlr->busy = false;
                                trace_spi_controller_idle(ctlr);
                        } else {
                                kthread_queue_work(ctlr->kworker,
                                                   &ctlr->pump_messages);
                        }
                        spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                        return;
                }

                ctlr->busy = false;
                ctlr->idling = true;
                spin_unlock_irqrestore(&ctlr->queue_lock, flags);

                kfree(ctlr->dummy_rx);
                ctlr->dummy_rx = NULL;
                kfree(ctlr->dummy_tx);
                ctlr->dummy_tx = NULL;
                if (ctlr->unprepare_transfer_hardware &&
                    ctlr->unprepare_transfer_hardware(ctlr))
                        dev_err(&ctlr->dev,
                                "failed to unprepare transfer hardware\n");
                spi_idle_runtime_pm(ctlr);
                trace_spi_controller_idle(ctlr);

                spin_lock_irqsave(&ctlr->queue_lock, flags);
                ctlr->idling = false;
                spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                return;
        }

        /* Extract head of queue */
        msg = list_first_entry(&ctlr->queue, struct spi_message, queue);
        ctlr->cur_msg = msg;

        list_del_init(&msg->queue);
        if (ctlr->busy)
                was_busy = true;
        else
                ctlr->busy = true;
        spin_unlock_irqrestore(&ctlr->queue_lock, flags);

        mutex_lock(&ctlr->io_mutex);

        if (!was_busy && ctlr->auto_runtime_pm) {
                ret = pm_runtime_get_sync(ctlr->dev.parent);
                if (ret < 0) {
                        pm_runtime_put_noidle(ctlr->dev.parent);
                        dev_err(&ctlr->dev, "Failed to power device: %d\n",
                                ret);
                        mutex_unlock(&ctlr->io_mutex);
                        return;
                }
        }

        if (!was_busy)
                trace_spi_controller_busy(ctlr);

        if (!was_busy && ctlr->prepare_transfer_hardware) {
                ret = ctlr->prepare_transfer_hardware(ctlr);
                if (ret) {
                        dev_err(&ctlr->dev,
                                "failed to prepare transfer hardware: %d\n",
                                ret);

                        if (ctlr->auto_runtime_pm)
                                pm_runtime_put(ctlr->dev.parent);

                        msg->status = ret;
                        spi_finalize_current_message(ctlr);

                        mutex_unlock(&ctlr->io_mutex);
                        return;
                }
        }

        trace_spi_message_start(msg);

        if (ctlr->prepare_message) {
                ret = ctlr->prepare_message(ctlr, msg);
                if (ret) {
                        dev_err(&ctlr->dev, "failed to prepare message: %d\n",
                                ret);
                        msg->status = ret;
                        spi_finalize_current_message(ctlr);
                        goto out;
                }
                ctlr->cur_msg_prepared = true;
        }

        ret = spi_map_msg(ctlr, msg);
        if (ret) {
                msg->status = ret;
                spi_finalize_current_message(ctlr);
                goto out;
        }

        if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
                list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                        xfer->ptp_sts_word_pre = 0;
                        ptp_read_system_prets(xfer->ptp_sts);
                }
        }

        ret = ctlr->transfer_one_message(ctlr, msg);
        if (ret) {
                dev_err(&ctlr->dev,
                        "failed to transfer one message from queue\n");
                goto out;
        }

out:
        mutex_unlock(&ctlr->io_mutex);

        /* Prod the scheduler in case transfer_one() was busy waiting */
        if (!ret)
                cond_resched();
}

/**
 * spi_pump_messages - kthread work function which processes spi message queue
 * @work: pointer to kthread work struct contained in the controller struct
 */
static void spi_pump_messages(struct kthread_work *work)
{
        struct spi_controller *ctlr =
                container_of(work, struct spi_controller, pump_messages);

        __spi_pump_messages(ctlr, true);
}

/**
 * spi_take_timestamp_pre - helper for drivers to collect the beginning of the
 *                          TX timestamp for the requested byte from the SPI
 *                          transfer. The frequency with which this function
 *                          must be called (once per word, once for the whole
 *                          transfer, once per batch of words etc) is arbitrary
 *                          as long as the @tx buffer offset is greater than or
 *                          equal to the requested byte at the time of the
 *                          call. The timestamp is only taken once, at the
 *                          first such call. It is assumed that the driver
 *                          advances its @tx buffer pointer monotonically.
 * @ctlr: Pointer to the spi_controller structure of the driver
 * @xfer: Pointer to the transfer being timestamped
 * @progress: How many words (not bytes) have been transferred so far
 * @irqs_off: If true, will disable IRQs and preemption for the duration of the
 *            transfer, for less jitter in time measurement. Only compatible
 *            with PIO drivers. If true, must follow up with
 *            spi_take_timestamp_post or otherwise system will crash.
 *            WARNING: for fully predictable results, the CPU frequency must
 *            also be under control (governor).
 */
void spi_take_timestamp_pre(struct spi_controller *ctlr,
                            struct spi_transfer *xfer,
                            size_t progress, bool irqs_off)
{
        if (!xfer->ptp_sts)
                return;

        if (xfer->timestamped)
                return;

        if (progress > xfer->ptp_sts_word_pre)
                return;

        /* Capture the resolution of the timestamp */
        xfer->ptp_sts_word_pre = progress;

        if (irqs_off) {
                local_irq_save(ctlr->irq_flags);
                preempt_disable();
        }

        ptp_read_system_prets(xfer->ptp_sts);
}
EXPORT_SYMBOL_GPL(spi_take_timestamp_pre);

/**
 * spi_take_timestamp_post - helper for drivers to collect the end of the
 *                           TX timestamp for the requested byte from the SPI
 *                           transfer. Can be called with an arbitrary
 *                           frequency: only the first call where @tx exceeds
 *                           or is equal to the requested word will be
 *                           timestamped.
 * @ctlr: Pointer to the spi_controller structure of the driver
 * @xfer: Pointer to the transfer being timestamped
 * @progress: How many words (not bytes) have been transferred so far
 * @irqs_off: If true, will re-enable IRQs and preemption for the local CPU.
 */
void spi_take_timestamp_post(struct spi_controller *ctlr,
                             struct spi_transfer *xfer,
                             size_t progress, bool irqs_off)
{
        if (!xfer->ptp_sts)
                return;

        if (xfer->timestamped)
                return;

        if (progress < xfer->ptp_sts_word_post)
                return;

        ptp_read_system_postts(xfer->ptp_sts);

        if (irqs_off) {
                local_irq_restore(ctlr->irq_flags);
                preempt_enable();
        }

        /* Capture the resolution of the timestamp */
        xfer->ptp_sts_word_post = progress;

        xfer->timestamped = true;
}
EXPORT_SYMBOL_GPL(spi_take_timestamp_post);

/**
 * spi_set_thread_rt - set the controller to pump at realtime priority
 * @ctlr: controller to boost priority of
 *
 * This can be called because the controller requested realtime priority
 * (by setting the ->rt value before calling spi_register_controller()) or
 * because a device on the bus said that its transfers needed realtime
 * priority.
 *
 * NOTE: at the moment if any device on a bus says it needs realtime then
 * the thread will be at realtime priority for all transfers on that
 * controller.  If this eventually becomes a problem we may see if we can
 * find a way to boost the priority only temporarily during relevant
 * transfers.
 */
static void spi_set_thread_rt(struct spi_controller *ctlr)
{
        dev_info(&ctlr->dev,
                "will run message pump with realtime priority\n");
        sched_set_fifo(ctlr->kworker->task);
}

static int spi_init_queue(struct spi_controller *ctlr)
{
        ctlr->running = false;
        ctlr->busy = false;

        ctlr->kworker = kthread_create_worker(0, dev_name(&ctlr->dev));
        if (IS_ERR(ctlr->kworker)) {
                dev_err(&ctlr->dev, "failed to create message pump kworker\n");
                return PTR_ERR(ctlr->kworker);
        }

        kthread_init_work(&ctlr->pump_messages, spi_pump_messages);

        /*
         * Controller config will indicate if this controller should run the
         * message pump with high (realtime) priority to reduce the transfer
         * latency on the bus by minimising the delay between a transfer
         * request and the scheduling of the message pump thread. Without this
         * setting the message pump thread will remain at default priority.
         */
        if (ctlr->rt)
                spi_set_thread_rt(ctlr);

        return 0;
}

/**
 * spi_get_next_queued_message() - called by driver to check for queued
 * messages
 * @ctlr: the controller to check for queued messages
 *
 * If there are more messages in the queue, the next message is returned from
 * this call.
 *
 * Return: the next message in the queue, else NULL if the queue is empty.
 */
struct spi_message *spi_get_next_queued_message(struct spi_controller *ctlr)
{
        struct spi_message *next;
        unsigned long flags;

        /* get a pointer to the next message, if any */
        spin_lock_irqsave(&ctlr->queue_lock, flags);
        next = list_first_entry_or_null(&ctlr->queue, struct spi_message,
                                        queue);
        spin_unlock_irqrestore(&ctlr->queue_lock, flags);

        return next;
}
EXPORT_SYMBOL_GPL(spi_get_next_queued_message);

/**
 * spi_finalize_current_message() - the current message is complete
 * @ctlr: the controller to return the message to
 *
 * Called by the driver to notify the core that the message in the front of the
 * queue is complete and can be removed from the queue.
 */
void spi_finalize_current_message(struct spi_controller *ctlr)
{
        struct spi_transfer *xfer;
        struct spi_message *mesg;
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&ctlr->queue_lock, flags);
        mesg = ctlr->cur_msg;
        spin_unlock_irqrestore(&ctlr->queue_lock, flags);

        if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
                list_for_each_entry(xfer, &mesg->transfers, transfer_list) {
                        ptp_read_system_postts(xfer->ptp_sts);
                        xfer->ptp_sts_word_post = xfer->len;
                }
        }

        if (unlikely(ctlr->ptp_sts_supported))
                list_for_each_entry(xfer, &mesg->transfers, transfer_list)
                        WARN_ON_ONCE(xfer->ptp_sts && !xfer->timestamped);

        spi_unmap_msg(ctlr, mesg);

        /* In the prepare_messages callback the spi bus has the opportunity to
         * split a transfer to smaller chunks.
         * Release splited transfers here since spi_map_msg is done on the
         * splited transfers.
         */
        spi_res_release(ctlr, mesg);

        if (ctlr->cur_msg_prepared && ctlr->unprepare_message) {
                ret = ctlr->unprepare_message(ctlr, mesg);
                if (ret) {
                        dev_err(&ctlr->dev, "failed to unprepare message: %d\n",
                                ret);
                }
        }

        spin_lock_irqsave(&ctlr->queue_lock, flags);
        ctlr->cur_msg = NULL;
        ctlr->cur_msg_prepared = false;
        ctlr->fallback = false;
        kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
        spin_unlock_irqrestore(&ctlr->queue_lock, flags);

        trace_spi_message_done(mesg);

        mesg->state = NULL;
        if (mesg->complete)
                mesg->complete(mesg->context);
}
EXPORT_SYMBOL_GPL(spi_finalize_current_message);

static int spi_start_queue(struct spi_controller *ctlr)
{
        unsigned long flags;

        spin_lock_irqsave(&ctlr->queue_lock, flags);

        if (ctlr->running || ctlr->busy) {
                spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                return -EBUSY;
        }

        ctlr->running = true;
        ctlr->cur_msg = NULL;
        spin_unlock_irqrestore(&ctlr->queue_lock, flags);

        kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);

        return 0;
}

static int spi_stop_queue(struct spi_controller *ctlr)
{
        unsigned long flags;
        unsigned limit = 500;
        int ret = 0;

        spin_lock_irqsave(&ctlr->queue_lock, flags);

        /*
         * This is a bit lame, but is optimized for the common execution path.
         * A wait_queue on the ctlr->busy could be used, but then the common
         * execution path (pump_messages) would be required to call wake_up or
         * friends on every SPI message. Do this instead.
         */
        while ((!list_empty(&ctlr->queue) || ctlr->busy) && limit--) {
                spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                usleep_range(10000, 11000);
                spin_lock_irqsave(&ctlr->queue_lock, flags);
        }

        if (!list_empty(&ctlr->queue) || ctlr->busy)
                ret = -EBUSY;
        else
                ctlr->running = false;

        spin_unlock_irqrestore(&ctlr->queue_lock, flags);

        if (ret) {
                dev_warn(&ctlr->dev, "could not stop message queue\n");
                return ret;
        }
        return ret;
}

static int spi_destroy_queue(struct spi_controller *ctlr)
{
        int ret;

        ret = spi_stop_queue(ctlr);

        /*
         * kthread_flush_worker will block until all work is done.
         * If the reason that stop_queue timed out is that the work will never
         * finish, then it does no good to call flush/stop thread, so
         * return anyway.
         */
        if (ret) {
                dev_err(&ctlr->dev, "problem destroying queue\n");
                return ret;
        }

        kthread_destroy_worker(ctlr->kworker);

        return 0;
}

static int __spi_queued_transfer(struct spi_device *spi,
                                 struct spi_message *msg,
                                 bool need_pump)
{
        struct spi_controller *ctlr = spi->controller;
        unsigned long flags;

        spin_lock_irqsave(&ctlr->queue_lock, flags);

        if (!ctlr->running) {
                spin_unlock_irqrestore(&ctlr->queue_lock, flags);
                return -ESHUTDOWN;
        }
        msg->actual_length = 0;
        msg->status = -EINPROGRESS;

        list_add_tail(&msg->queue, &ctlr->queue);
        if (!ctlr->busy && need_pump)
                kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);

        spin_unlock_irqrestore(&ctlr->queue_lock, flags);
        return 0;
}

/**
 * spi_queued_transfer - transfer function for queued transfers
 * @spi: spi device which is requesting transfer
 * @msg: spi message which is to handled is queued to driver queue
 *
 * Return: zero on success, else a negative error code.
 */
static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
{
        return __spi_queued_transfer(spi, msg, true);
}

static int spi_controller_initialize_queue(struct spi_controller *ctlr)
{
        int ret;

        ctlr->transfer = spi_queued_transfer;
        if (!ctlr->transfer_one_message)
                ctlr->transfer_one_message = spi_transfer_one_message;

        /* Initialize and start queue */
        ret = spi_init_queue(ctlr);
        if (ret) {
                dev_err(&ctlr->dev, "problem initializing queue\n");
                goto err_init_queue;
        }
        ctlr->queued = true;
        ret = spi_start_queue(ctlr);
        if (ret) {
                dev_err(&ctlr->dev, "problem starting queue\n");
                goto err_start_queue;
        }

        return 0;

err_start_queue:
        spi_destroy_queue(ctlr);
err_init_queue:
        return ret;
}

/**
 * spi_flush_queue - Send all pending messages in the queue from the callers'
 *                   context
 * @ctlr: controller to process queue for
 *
 * This should be used when one wants to ensure all pending messages have been
 * sent before doing something. Is used by the spi-mem code to make sure SPI
 * memory operations do not preempt regular SPI transfers that have been queued
 * before the spi-mem operation.
 */
void spi_flush_queue(struct spi_controller *ctlr)
{
        if (ctlr->transfer == spi_queued_transfer)
                __spi_pump_messages(ctlr, false);
}

/*-------------------------------------------------------------------------*/

#if defined(CONFIG_OF)
static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
                           struct device_node *nc)
{
        u32 value;
        int rc;

        /* Mode (clock phase/polarity/etc.) */
        if (of_property_read_bool(nc, "spi-cpha"))
                spi->mode |= SPI_CPHA;
        if (of_property_read_bool(nc, "spi-cpol"))
                spi->mode |= SPI_CPOL;
        if (of_property_read_bool(nc, "spi-3wire"))
                spi->mode |= SPI_3WIRE;
        if (of_property_read_bool(nc, "spi-lsb-first"))
                spi->mode |= SPI_LSB_FIRST;
        if (of_property_read_bool(nc, "spi-cs-high"))
                spi->mode |= SPI_CS_HIGH;

        /* Device DUAL/QUAD mode */
        if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
                switch (value) {
                case 1:
                        break;
                case 2:
                        spi->mode |= SPI_TX_DUAL;
                        break;
                case 4:
                        spi->mode |= SPI_TX_QUAD;
                        break;
                case 8:
                        spi->mode |= SPI_TX_OCTAL;
                        break;
                default:
                        dev_warn(&ctlr->dev,
                                "spi-tx-bus-width %d not supported\n",
                                value);
                        break;
                }
        }

        if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
                switch (value) {
                case 1:
                        break;
                case 2:
                        spi->mode |= SPI_RX_DUAL;
                        break;
                case 4:
                        spi->mode |= SPI_RX_QUAD;
                        break;
                case 8:
                        spi->mode |= SPI_RX_OCTAL;
                        break;
                default:
                        dev_warn(&ctlr->dev,
                                "spi-rx-bus-width %d not supported\n",
                                value);
                        break;
                }
        }

        if (spi_controller_is_slave(ctlr)) {
                if (!of_node_name_eq(nc, "slave")) {
                        dev_err(&ctlr->dev, "%pOF is not called 'slave'\n",
                                nc);
                        return -EINVAL;
                }
                return 0;
        }

        /* Device address */
        rc = of_property_read_u32(nc, "reg", &value);
        if (rc) {
                dev_err(&ctlr->dev, "%pOF has no valid 'reg' property (%d)\n",
                        nc, rc);
                return rc;
        }
        spi->chip_select = value;

        /* Device speed */
        if (!of_property_read_u32(nc, "spi-max-frequency", &value))
                spi->max_speed_hz = value;

        return 0;
}

static struct spi_device *
of_register_spi_device(struct spi_controller *ctlr, struct device_node *nc)
{
        struct spi_device *spi;
        int rc;

        /* Alloc an spi_device */
        spi = spi_alloc_device(ctlr);
        if (!spi) {
                dev_err(&ctlr->dev, "spi_device alloc error for %pOF\n", nc);
                rc = -ENOMEM;
                goto err_out;
        }

        /* Select device driver */
        rc = of_modalias_node(nc, spi->modalias,
                                sizeof(spi->modalias));
        if (rc < 0) {
                dev_err(&ctlr->dev, "cannot find modalias for %pOF\n", nc);
                goto err_out;
        }

        rc = of_spi_parse_dt(ctlr, spi, nc);
        if (rc)
                goto err_out;

        /* Store a pointer to the node in the device structure */
        of_node_get(nc);
        spi->dev.of_node = nc;

        /* Register the new device */
        rc = spi_add_device(spi);
        if (rc) {
                dev_err(&ctlr->dev, "spi_device register error %pOF\n", nc);
                goto err_of_node_put;
        }

        return spi;

err_of_node_put:
        of_node_put(nc);
err_out:
        spi_dev_put(spi);
        return ERR_PTR(rc);
}

/**
 * of_register_spi_devices() - Register child devices onto the SPI bus
 * @ctlr:       Pointer to spi_controller device
 *
 * Registers an spi_device for each child node of controller node which
 * represents a valid SPI slave.
 */
static void of_register_spi_devices(struct spi_controller *ctlr)
{
        struct spi_device *spi;
        struct device_node *nc;

        if (!ctlr->dev.of_node)
                return;

        for_each_available_child_of_node(ctlr->dev.of_node, nc) {
                if (of_node_test_and_set_flag(nc, OF_POPULATED))
                        continue;
                spi = of_register_spi_device(ctlr, nc);
                if (IS_ERR(spi)) {
                        dev_warn(&ctlr->dev,
                                 "Failed to create SPI device for %pOF\n", nc);
                        of_node_clear_flag(nc, OF_POPULATED);
                }
        }
}
#else
static void of_register_spi_devices(struct spi_controller *ctlr) { }
#endif

#ifdef CONFIG_ACPI
struct acpi_spi_lookup {
        struct spi_controller   *ctlr;
        u32                     max_speed_hz;
        u32                     mode;
        int                     irq;
        u8                      bits_per_word;
        u8                      chip_select;
};

static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
                                            struct acpi_spi_lookup *lookup)
{
        const union acpi_object *obj;

        if (!x86_apple_machine)
                return;

        if (!acpi_dev_get_property(dev, "spiSclkPeriod", ACPI_TYPE_BUFFER, &obj)
            && obj->buffer.length >= 4)
                lookup->max_speed_hz  = NSEC_PER_SEC / *(u32 *)obj->buffer.pointer;

        if (!acpi_dev_get_property(dev, "spiWordSize", ACPI_TYPE_BUFFER, &obj)
            && obj->buffer.length == 8)
                lookup->bits_per_word = *(u64 *)obj->buffer.pointer;

        if (!acpi_dev_get_property(dev, "spiBitOrder", ACPI_TYPE_BUFFER, &obj)
            && obj->buffer.length == 8 && !*(u64 *)obj->buffer.pointer)
                lookup->mode |= SPI_LSB_FIRST;

        if (!acpi_dev_get_property(dev, "spiSPO", ACPI_TYPE_BUFFER, &obj)
            && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
                lookup->mode |= SPI_CPOL;

        if (!acpi_dev_get_property(dev, "spiSPH", ACPI_TYPE_BUFFER, &obj)
            && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
                lookup->mode |= SPI_CPHA;
}

static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
{
        struct acpi_spi_lookup *lookup = data;
        struct spi_controller *ctlr = lookup->ctlr;

        if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
                struct acpi_resource_spi_serialbus *sb;
                acpi_handle parent_handle;
                acpi_status status;

                sb = &ares->data.spi_serial_bus;
                if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {

                        status = acpi_get_handle(NULL,
                                                 sb->resource_source.string_ptr,
                                                 &parent_handle);

                        if (ACPI_FAILURE(status) ||
                            ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
                                return -ENODEV;

                        /*
                         * ACPI DeviceSelection numbering is handled by the
                         * host controller driver in Windows and can vary
                         * from driver to driver. In Linux we always expect
                         * 0 .. max - 1 so we need to ask the driver to
                         * translate between the two schemes.
                         */
                        if (ctlr->fw_translate_cs) {
                                int cs = ctlr->fw_translate_cs(ctlr,
                                                sb->device_selection);
                                if (cs < 0)
                                        return cs;
                                lookup->chip_select = cs;
                        } else {
                                lookup->chip_select = sb->device_selection;
                        }

                        lookup->max_speed_hz = sb->connection_speed;
                        lookup->bits_per_word = sb->data_bit_length;

                        if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
                                lookup->mode |= SPI_CPHA;
                        if (sb->clock_polarity == ACPI_SPI_START_HIGH)
                                lookup->mode |= SPI_CPOL;
                        if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
                                lookup->mode |= SPI_CS_HIGH;
                }
        } else if (lookup->irq < 0) {
                struct resource r;

                if (acpi_dev_resource_interrupt(ares, 0, &r))
                        lookup->irq = r.start;
        }

        /* Always tell the ACPI core to skip this resource */
        return 1;
}

static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
                                            struct acpi_device *adev)
{
        acpi_handle parent_handle = NULL;
        struct list_head resource_list;
        struct acpi_spi_lookup lookup = {};
        struct spi_device *spi;
        int ret;

        if (acpi_bus_get_status(adev) || !adev->status.present ||
            acpi_device_enumerated(adev))
                return AE_OK;

        lookup.ctlr             = ctlr;
        lookup.irq              = -1;

        INIT_LIST_HEAD(&resource_list);
        ret = acpi_dev_get_resources(adev, &resource_list,
                                     acpi_spi_add_resource, &lookup);
        acpi_dev_free_resource_list(&resource_list);

        if (ret < 0)
                /* found SPI in _CRS but it points to another controller */
                return AE_OK;

        if (!lookup.max_speed_hz &&
            !ACPI_FAILURE(acpi_get_parent(adev->handle, &parent_handle)) &&
            ACPI_HANDLE(ctlr->dev.parent) == parent_handle) {
                /* Apple does not use _CRS but nested devices for SPI slaves */
                acpi_spi_parse_apple_properties(adev, &lookup);
        }

        if (!lookup.max_speed_hz)
                return AE_OK;

        spi = spi_alloc_device(ctlr);
        if (!spi) {
                dev_err(&ctlr->dev, "failed to allocate SPI device for %s\n",
                        dev_name(&adev->dev));
                return AE_NO_MEMORY;
        }


        ACPI_COMPANION_SET(&spi->dev, adev);
        spi->max_speed_hz       = lookup.max_speed_hz;
        spi->mode               |= lookup.mode;
        spi->irq                = lookup.irq;
        spi->bits_per_word      = lookup.bits_per_word;
        spi->chip_select        = lookup.chip_select;

        acpi_set_modalias(adev, acpi_device_hid(adev), spi->modalias,
                          sizeof(spi->modalias));

        if (spi->irq < 0)
                spi->irq = acpi_dev_gpio_irq_get(adev, 0);

        acpi_device_set_enumerated(adev);

        adev->power.flags.ignore_parent = true;
        if (spi_add_device(spi)) {
                adev->power.flags.ignore_parent = false;
                dev_err(&ctlr->dev, "failed to add SPI device %s from ACPI\n",
                        dev_name(&adev->dev));
                spi_dev_put(spi);
        }

        return AE_OK;
}

static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
                                       void *data, void **return_value)
{
        struct spi_controller *ctlr = data;
        struct acpi_device *adev;

        if (acpi_bus_get_device(handle, &adev))
                return AE_OK;

        return acpi_register_spi_device(ctlr, adev);
}

#define SPI_ACPI_ENUMERATE_MAX_DEPTH            32

static void acpi_register_spi_devices(struct spi_controller *ctlr)
{
        acpi_status status;
        acpi_handle handle;

        handle = ACPI_HANDLE(ctlr->dev.parent);
        if (!handle)
                return;

        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
                                     SPI_ACPI_ENUMERATE_MAX_DEPTH,
                                     acpi_spi_add_device, NULL, ctlr, NULL);
        if (ACPI_FAILURE(status))
                dev_warn(&ctlr->dev, "failed to enumerate SPI slaves\n");
}
#else
static inline void acpi_register_spi_devices(struct spi_controller *ctlr) {}
#endif /* CONFIG_ACPI */

static void spi_controller_release(struct device *dev)
{
        struct spi_controller *ctlr;

        ctlr = container_of(dev, struct spi_controller, dev);
        kfree(ctlr);
}

static struct class spi_master_class = {
        .name           = "spi_master",
        .owner          = THIS_MODULE,
        .dev_release    = spi_controller_release,
        .dev_groups     = spi_master_groups,
};

#ifdef CONFIG_SPI_SLAVE
/**
 * spi_slave_abort - abort the ongoing transfer request on an SPI slave
 *                   controller
 * @spi: device used for the current transfer
 */
int spi_slave_abort(struct spi_device *spi)
{
        struct spi_controller *ctlr = spi->controller;

        if (spi_controller_is_slave(ctlr) && ctlr->slave_abort)
                return ctlr->slave_abort(ctlr);

        return -ENOTSUPP;
}
EXPORT_SYMBOL_GPL(spi_slave_abort);

static int match_true(struct device *dev, void *data)
{
        return 1;
}

static ssize_t slave_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct spi_controller *ctlr = container_of(dev, struct spi_controller,
                                                   dev);
        struct device *child;

        child = device_find_child(&ctlr->dev, NULL, match_true);
        return sprintf(buf, "%s\n",
                       child ? to_spi_device(child)->modalias : NULL);
}

static ssize_t slave_store(struct device *dev, struct device_attribute *attr,
                           const char *buf, size_t count)
{
        struct spi_controller *ctlr = container_of(dev, struct spi_controller,
                                                   dev);
        struct spi_device *spi;
        struct device *child;
        char name[32];
        int rc;

        rc = sscanf(buf, "%31s", name);
        if (rc != 1 || !name[0])
                return -EINVAL;

        child = device_find_child(&ctlr->dev, NULL, match_true);
        if (child) {
                /* Remove registered slave */
                device_unregister(child);
                put_device(child);
        }

        if (strcmp(name, "(null)")) {
                /* Register new slave */
                spi = spi_alloc_device(ctlr);
                if (!spi)
                        return -ENOMEM;

                strlcpy(spi->modalias, name, sizeof(spi->modalias));

                rc = spi_add_device(spi);
                if (rc) {
                        spi_dev_put(spi);
                        return rc;
                }
        }

        return count;
}

static DEVICE_ATTR_RW(slave);

static struct attribute *spi_slave_attrs[] = {
        &dev_attr_slave.attr,
        NULL,
};

static const struct attribute_group spi_slave_group = {
        .attrs = spi_slave_attrs,
};

static const struct attribute_group *spi_slave_groups[] = {
        &spi_controller_statistics_group,
        &spi_slave_group,
        NULL,
};

static struct class spi_slave_class = {
        .name           = "spi_slave",
        .owner          = THIS_MODULE,
        .dev_release    = spi_controller_release,
        .dev_groups     = spi_slave_groups,
};
#else
extern struct class spi_slave_class;    /* dummy */
#endif

/**
 * __spi_alloc_controller - allocate an SPI master or slave controller
 * @dev: the controller, possibly using the platform_bus
 * @size: how much zeroed driver-private data to allocate; the pointer to this
 *      memory is in the driver_data field of the returned device, accessible
 *      with spi_controller_get_devdata(); the memory is cacheline aligned;
 *      drivers granting DMA access to portions of their private data need to
 *      round up @size using ALIGN(size, dma_get_cache_alignment()).
 * @slave: flag indicating whether to allocate an SPI master (false) or SPI
 *      slave (true) controller
 * Context: can sleep
 *
 * This call is used only by SPI controller drivers, which are the
 * only ones directly touching chip registers.  It's how they allocate
 * an spi_controller structure, prior to calling spi_register_controller().
 *
 * This must be called from context that can sleep.
 *
 * The caller is responsible for assigning the bus number and initializing the
 * controller's methods before calling spi_register_controller(); and (after
 * errors adding the device) calling spi_controller_put() to prevent a memory
 * leak.
 *
 * Return: the SPI controller structure on success, else NULL.
 */
struct spi_controller *__spi_alloc_controller(struct device *dev,
                                              unsigned int size, bool slave)
{
        struct spi_controller   *ctlr;
        size_t ctlr_size = ALIGN(sizeof(*ctlr), dma_get_cache_alignment());

        if (!dev)
                return NULL;

        ctlr = kzalloc(size + ctlr_size, GFP_KERNEL);
        if (!ctlr)
                return NULL;

        device_initialize(&ctlr->dev);
        ctlr->bus_num = -1;
        ctlr->num_chipselect = 1;
        ctlr->slave = slave;
        if (IS_ENABLED(CONFIG_SPI_SLAVE) && slave)
                ctlr->dev.class = &spi_slave_class;
        else
                ctlr->dev.class = &spi_master_class;
        ctlr->dev.parent = dev;
        pm_suspend_ignore_children(&ctlr->dev, true);
        spi_controller_set_devdata(ctlr, (void *)ctlr + ctlr_size);

        return ctlr;
}
EXPORT_SYMBOL_GPL(__spi_alloc_controller);

static void devm_spi_release_controller(struct device *dev, void *ctlr)
{
        spi_controller_put(*(struct spi_controller **)ctlr);
}

/**
 * __devm_spi_alloc_controller - resource-managed __spi_alloc_controller()
 * @dev: physical device of SPI controller
 * @size: how much zeroed driver-private data to allocate
 * @slave: whether to allocate an SPI master (false) or SPI slave (true)
 * Context: can sleep
 *
 * Allocate an SPI controller and automatically release a reference on it
 * when @dev is unbound from its driver.  Drivers are thus relieved from
 * having to call spi_controller_put().
 *
 * The arguments to this function are identical to __spi_alloc_controller().
 *
 * Return: the SPI controller structure on success, else NULL.
 */
struct spi_controller *__devm_spi_alloc_controller(struct device *dev,
                                                   unsigned int size,
                                                   bool slave)
{
        struct spi_controller **ptr, *ctlr;

        ptr = devres_alloc(devm_spi_release_controller, sizeof(*ptr),
                           GFP_KERNEL);
        if (!ptr)
                return NULL;

        ctlr = __spi_alloc_controller(dev, size, slave);
        if (ctlr) {
                *ptr = ctlr;
                devres_add(dev, ptr);
        } else {
                devres_free(ptr);
        }

        return ctlr;
}
EXPORT_SYMBOL_GPL(__devm_spi_alloc_controller);

#ifdef CONFIG_OF
static int of_spi_get_gpio_numbers(struct spi_controller *ctlr)
{
        int nb, i, *cs;
        struct device_node *np = ctlr->dev.of_node;

        if (!np)
                return 0;

        nb = of_gpio_named_count(np, "cs-gpios");
        ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);

        /* Return error only for an incorrectly formed cs-gpios property */
        if (nb == 0 || nb == -ENOENT)
                return 0;
        else if (nb < 0)
                return nb;

        cs = devm_kcalloc(&ctlr->dev, ctlr->num_chipselect, sizeof(int),
                          GFP_KERNEL);
        ctlr->cs_gpios = cs;

        if (!ctlr->cs_gpios)
                return -ENOMEM;

        for (i = 0; i < ctlr->num_chipselect; i++)
                cs[i] = -ENOENT;

        for (i = 0; i < nb; i++)
                cs[i] = of_get_named_gpio(np, "cs-gpios", i);

        return 0;
}
#else
static int of_spi_get_gpio_numbers(struct spi_controller *ctlr)
{
        return 0;
}
#endif

/**
 * spi_get_gpio_descs() - grab chip select GPIOs for the master
 * @ctlr: The SPI master to grab GPIO descriptors for
 */
static int spi_get_gpio_descs(struct spi_controller *ctlr)
{
        int nb, i;
        struct gpio_desc **cs;
        struct device *dev = &ctlr->dev;
        unsigned long native_cs_mask = 0;
        unsigned int num_cs_gpios = 0;

        nb = gpiod_count(dev, "cs");
        ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);

        /* No GPIOs at all is fine, else return the error */
        if (nb == 0 || nb == -ENOENT)
                return 0;
        else if (nb < 0)
                return nb;

        cs = devm_kcalloc(dev, ctlr->num_chipselect, sizeof(*cs),
                          GFP_KERNEL);
        if (!cs)
                return -ENOMEM;
        ctlr->cs_gpiods = cs;

        for (i = 0; i < nb; i++) {
                /*
                 * Most chipselects are active low, the inverted
                 * semantics are handled by special quirks in gpiolib,
                 * so initializing them GPIOD_OUT_LOW here means
                 * "unasserted", in most cases this will drive the physical
                 * line high.
                 */
                cs[i] = devm_gpiod_get_index_optional(dev, "cs", i,
                                                      GPIOD_OUT_LOW);
                if (IS_ERR(cs[i]))
                        return PTR_ERR(cs[i]);

                if (cs[i]) {
                        /*
                         * If we find a CS GPIO, name it after the device and
                         * chip select line.
                         */
                        char *gpioname;

                        gpioname = devm_kasprintf(dev, GFP_KERNEL, "%s CS%d",
                                                  dev_name(dev), i);
                        if (!gpioname)
                                return -ENOMEM;
                        gpiod_set_consumer_name(cs[i], gpioname);
                        num_cs_gpios++;
                        continue;
                }

                if (ctlr->max_native_cs && i >= ctlr->max_native_cs) {
                        dev_err(dev, "Invalid native chip select %d\n", i);
                        return -EINVAL;
                }
                native_cs_mask |= BIT(i);
        }

        ctlr->unused_native_cs = ffz(native_cs_mask);
        if (num_cs_gpios && ctlr->max_native_cs &&
            ctlr->unused_native_cs >= ctlr->max_native_cs) {
                dev_err(dev, "No unused native chip select available\n");
                return -EINVAL;
        }

        return 0;
}

static int spi_controller_check_ops(struct spi_controller *ctlr)
{
        /*
         * The controller may implement only the high-level SPI-memory like
         * operations if it does not support regular SPI transfers, and this is
         * valid use case.
         * If ->mem_ops is NULL, we request that at least one of the
         * ->transfer_xxx() method be implemented.
         */
        if (ctlr->mem_ops) {
                if (!ctlr->mem_ops->exec_op)
                        return -EINVAL;
        } else if (!ctlr->transfer && !ctlr->transfer_one &&
                   !ctlr->transfer_one_message) {
                return -EINVAL;
        }

        return 0;
}

/**
 * spi_register_controller - register SPI master or slave controller
 * @ctlr: initialized master, originally from spi_alloc_master() or
 *      spi_alloc_slave()
 * Context: can sleep
 *
 * SPI controllers connect to their drivers using some non-SPI bus,
 * such as the platform bus.  The final stage of probe() in that code
 * includes calling spi_register_controller() to hook up to this SPI bus glue.
 *
 * SPI controllers use board specific (often SOC specific) bus numbers,
 * and board-specific addressing for SPI devices combines those numbers
 * with chip select numbers.  Since SPI does not directly support dynamic
 * device identification, boards need configuration tables telling which
 * chip is at which address.
 *
 * This must be called from context that can sleep.  It returns zero on
 * success, else a negative error code (dropping the controller's refcount).
 * After a successful return, the caller is responsible for calling
 * spi_unregister_controller().
 *
 * Return: zero on success, else a negative error code.
 */
int spi_register_controller(struct spi_controller *ctlr)
{
        struct device           *dev = ctlr->dev.parent;
        struct boardinfo        *bi;
        int                     status;
        int                     id, first_dynamic;

        if (!dev)
                return -ENODEV;

        /*
         * Make sure all necessary hooks are implemented before registering
         * the SPI controller.
         */
        status = spi_controller_check_ops(ctlr);
        if (status)
                return status;

        if (ctlr->bus_num >= 0) {
                /* devices with a fixed bus num must check-in with the num */
                mutex_lock(&board_lock);
                id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
                        ctlr->bus_num + 1, GFP_KERNEL);
                mutex_unlock(&board_lock);
                if (WARN(id < 0, "couldn't get idr"))
                        return id == -ENOSPC ? -EBUSY : id;
                ctlr->bus_num = id;
        } else if (ctlr->dev.of_node) {
                /* allocate dynamic bus number using Linux idr */
                id = of_alias_get_id(ctlr->dev.of_node, "spi");
                if (id >= 0) {
                        ctlr->bus_num = id;
                        mutex_lock(&board_lock);
                        id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
                                       ctlr->bus_num + 1, GFP_KERNEL);
                        mutex_unlock(&board_lock);
                        if (WARN(id < 0, "couldn't get idr"))
                                return id == -ENOSPC ? -EBUSY : id;
                }
        }
        if (ctlr->bus_num < 0) {
                first_dynamic = of_alias_get_highest_id("spi");
                if (first_dynamic < 0)
                        first_dynamic = 0;
                else
                        first_dynamic++;

                mutex_lock(&board_lock);
                id = idr_alloc(&spi_master_idr, ctlr, first_dynamic,
                               0, GFP_KERNEL);
                mutex_unlock(&board_lock);
                if (WARN(id < 0, "couldn't get idr"))
                        return id;
                ctlr->bus_num = id;
        }
        INIT_LIST_HEAD(&ctlr->queue);
        spin_lock_init(&ctlr->queue_lock);
        spin_lock_init(&ctlr->bus_lock_spinlock);
        mutex_init(&ctlr->bus_lock_mutex);
        mutex_init(&ctlr->io_mutex);
        ctlr->bus_lock_flag = 0;
        init_completion(&ctlr->xfer_completion);
        if (!ctlr->max_dma_len)
                ctlr->max_dma_len = INT_MAX;

        /* register the device, then userspace will see it.
         * registration fails if the bus ID is in use.
         */
        dev_set_name(&ctlr->dev, "spi%u", ctlr->bus_num);

        if (!spi_controller_is_slave(ctlr)) {
                if (ctlr->use_gpio_descriptors) {
                        status = spi_get_gpio_descs(ctlr);
                        if (status)
                                goto free_bus_id;
                        /*
                         * A controller using GPIO descriptors always
                         * supports SPI_CS_HIGH if need be.
                         */
                        ctlr->mode_bits |= SPI_CS_HIGH;
                } else {
                        /* Legacy code path for GPIOs from DT */
                        status = of_spi_get_gpio_numbers(ctlr);
                        if (status)
                                goto free_bus_id;
                }
        }

        /*
         * Even if it's just one always-selected device, there must
         * be at least one chipselect.
         */
        if (!ctlr->num_chipselect) {
                status = -EINVAL;
                goto free_bus_id;
        }

        status = device_add(&ctlr->dev);
        if (status < 0)
                goto free_bus_id;
        dev_dbg(dev, "registered %s %s\n",
                        spi_controller_is_slave(ctlr) ? "slave" : "master",
                        dev_name(&ctlr->dev));

        /*
         * If we're using a queued driver, start the queue. Note that we don't
         * need the queueing logic if the driver is only supporting high-level
         * memory operations.
         */
        if (ctlr->transfer) {
                dev_info(dev, "controller is unqueued, this is deprecated\n");
        } else if (ctlr->transfer_one || ctlr->transfer_one_message) {
                status = spi_controller_initialize_queue(ctlr);
                if (status) {
                        device_del(&ctlr->dev);
                        goto free_bus_id;
                }
        }
        /* add statistics */
        spin_lock_init(&ctlr->statistics.lock);

        mutex_lock(&board_lock);
        list_add_tail(&ctlr->list, &spi_controller_list);
        list_for_each_entry(bi, &board_list, list)
                spi_match_controller_to_boardinfo(ctlr, &bi->board_info);
        mutex_unlock(&board_lock);

        /* Register devices from the device tree and ACPI */
        of_register_spi_devices(ctlr);
        acpi_register_spi_devices(ctlr);
        return status;

free_bus_id:
        mutex_lock(&board_lock);
        idr_remove(&spi_master_idr, ctlr->bus_num);
        mutex_unlock(&board_lock);
        return status;
}
EXPORT_SYMBOL_GPL(spi_register_controller);

static void devm_spi_unregister(struct device *dev, void *res)
{
        spi_unregister_controller(*(struct spi_controller **)res);
}

/**
 * devm_spi_register_controller - register managed SPI master or slave
 *      controller
 * @dev:    device managing SPI controller
 * @ctlr: initialized controller, originally from spi_alloc_master() or
 *      spi_alloc_slave()
 * Context: can sleep
 *
 * Register a SPI device as with spi_register_controller() which will
 * automatically be unregistered and freed.
 *
 * Return: zero on success, else a negative error code.
 */
int devm_spi_register_controller(struct device *dev,
                                 struct spi_controller *ctlr)
{
        struct spi_controller **ptr;
        int ret;

        ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                return -ENOMEM;

        ret = spi_register_controller(ctlr);
        if (!ret) {
                *ptr = ctlr;
                devres_add(dev, ptr);
        } else {
                devres_free(ptr);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(devm_spi_register_controller);

static int devm_spi_match_controller(struct device *dev, void *res, void *ctlr)
{
        return *(struct spi_controller **)res == ctlr;
}

static int __unregister(struct device *dev, void *null)
{
        spi_unregister_device(to_spi_device(dev));
        return 0;
}

/**
 * spi_unregister_controller - unregister SPI master or slave controller
 * @ctlr: the controller being unregistered
 * Context: can sleep
 *
 * This call is used only by SPI controller drivers, which are the
 * only ones directly touching chip registers.
 *
 * This must be called from context that can sleep.
 *
 * Note that this function also drops a reference to the controller.
 */
void spi_unregister_controller(struct spi_controller *ctlr)
{
        struct spi_controller *found;
        int id = ctlr->bus_num;

        /* Prevent addition of new devices, unregister existing ones */
        if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
                mutex_lock(&spi_add_lock);

        device_for_each_child(&ctlr->dev, NULL, __unregister);

        /* First make sure that this controller was ever added */
        mutex_lock(&board_lock);
        found = idr_find(&spi_master_idr, id);
        mutex_unlock(&board_lock);
        if (ctlr->queued) {
                if (spi_destroy_queue(ctlr))
                        dev_err(&ctlr->dev, "queue remove failed\n");
        }
        mutex_lock(&board_lock);
        list_del(&ctlr->list);
        mutex_unlock(&board_lock);

        device_del(&ctlr->dev);

        /* Release the last reference on the controller if its driver
         * has not yet been converted to devm_spi_alloc_master/slave().
         */
        if (!devres_find(ctlr->dev.parent, devm_spi_release_controller,
                         devm_spi_match_controller, ctlr))
                put_device(&ctlr->dev);

        /* free bus id */
        mutex_lock(&board_lock);
        if (found == ctlr)
                idr_remove(&spi_master_idr, id);
        mutex_unlock(&board_lock);

        if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
                mutex_unlock(&spi_add_lock);
}
EXPORT_SYMBOL_GPL(spi_unregister_controller);

int spi_controller_suspend(struct spi_controller *ctlr)
{
        int ret;

        /* Basically no-ops for non-queued controllers */
        if (!ctlr->queued)
                return 0;

        ret = spi_stop_queue(ctlr);
        if (ret)
                dev_err(&ctlr->dev, "queue stop failed\n");

        return ret;
}
EXPORT_SYMBOL_GPL(spi_controller_suspend);

int spi_controller_resume(struct spi_controller *ctlr)
{
        int ret;

        if (!ctlr->queued)
                return 0;

        ret = spi_start_queue(ctlr);
        if (ret)
                dev_err(&ctlr->dev, "queue restart failed\n");

        return ret;
}
EXPORT_SYMBOL_GPL(spi_controller_resume);

static int __spi_controller_match(struct device *dev, const void *data)
{
        struct spi_controller *ctlr;
        const u16 *bus_num = data;

        ctlr = container_of(dev, struct spi_controller, dev);
        return ctlr->bus_num == *bus_num;
}

/**
 * spi_busnum_to_master - look up master associated with bus_num
 * @bus_num: the master's bus number
 * Context: can sleep
 *
 * This call may be used with devices that are registered after
 * arch init time.  It returns a refcounted pointer to the relevant
 * spi_controller (which the caller must release), or NULL if there is
 * no such master registered.
 *
 * Return: the SPI master structure on success, else NULL.
 */
struct spi_controller *spi_busnum_to_master(u16 bus_num)
{
        struct device           *dev;
        struct spi_controller   *ctlr = NULL;

        dev = class_find_device(&spi_master_class, NULL, &bus_num,
                                __spi_controller_match);
        if (dev)
                ctlr = container_of(dev, struct spi_controller, dev);
        /* reference got in class_find_device */
        return ctlr;
}
EXPORT_SYMBOL_GPL(spi_busnum_to_master);

/*-------------------------------------------------------------------------*/

/* Core methods for SPI resource management */

/**
 * spi_res_alloc - allocate a spi resource that is life-cycle managed
 *                 during the processing of a spi_message while using
 *                 spi_transfer_one
 * @spi:     the spi device for which we allocate memory
 * @release: the release code to execute for this resource
 * @size:    size to alloc and return
 * @gfp:     GFP allocation flags
 *
 * Return: the pointer to the allocated data
 *
 * This may get enhanced in the future to allocate from a memory pool
 * of the @spi_device or @spi_controller to avoid repeated allocations.
 */
void *spi_res_alloc(struct spi_device *spi,
                    spi_res_release_t release,
                    size_t size, gfp_t gfp)
{
        struct spi_res *sres;

        sres = kzalloc(sizeof(*sres) + size, gfp);
        if (!sres)
                return NULL;

        INIT_LIST_HEAD(&sres->entry);
        sres->release = release;

        return sres->data;
}
EXPORT_SYMBOL_GPL(spi_res_alloc);

/**
 * spi_res_free - free an spi resource
 * @res: pointer to the custom data of a resource
 *
 */
void spi_res_free(void *res)
{
        struct spi_res *sres = container_of(res, struct spi_res, data);

        if (!res)
                return;

        WARN_ON(!list_empty(&sres->entry));
        kfree(sres);
}
EXPORT_SYMBOL_GPL(spi_res_free);

/**
 * spi_res_add - add a spi_res to the spi_message
 * @message: the spi message
 * @res:     the spi_resource
 */
void spi_res_add(struct spi_message *message, void *res)
{
        struct spi_res *sres = container_of(res, struct spi_res, data);

        WARN_ON(!list_empty(&sres->entry));
        list_add_tail(&sres->entry, &message->resources);
}
EXPORT_SYMBOL_GPL(spi_res_add);

/**
 * spi_res_release - release all spi resources for this message
 * @ctlr:  the @spi_controller
 * @message: the @spi_message
 */
void spi_res_release(struct spi_controller *ctlr, struct spi_message *message)
{
        struct spi_res *res, *tmp;

        list_for_each_entry_safe_reverse(res, tmp, &message->resources, entry) {
                if (res->release)
                        res->release(ctlr, message, res->data);

                list_del(&res->entry);

                kfree(res);
        }
}
EXPORT_SYMBOL_GPL(spi_res_release);

/*-------------------------------------------------------------------------*/

/* Core methods for spi_message alterations */

static void __spi_replace_transfers_release(struct spi_controller *ctlr,
                                            struct spi_message *msg,
                                            void *res)
{
        struct spi_replaced_transfers *rxfer = res;
        size_t i;

        /* call extra callback if requested */
        if (rxfer->release)
                rxfer->release(ctlr, msg, res);

        /* insert replaced transfers back into the message */
        list_splice(&rxfer->replaced_transfers, rxfer->replaced_after);

        /* remove the formerly inserted entries */
        for (i = 0; i < rxfer->inserted; i++)
                list_del(&rxfer->inserted_transfers[i].transfer_list);
}

/**
 * spi_replace_transfers - replace transfers with several transfers
 *                         and register change with spi_message.resources
 * @msg:           the spi_message we work upon
 * @xfer_first:    the first spi_transfer we want to replace
 * @remove:        number of transfers to remove
 * @insert:        the number of transfers we want to insert instead
 * @release:       extra release code necessary in some circumstances
 * @extradatasize: extra data to allocate (with alignment guarantees
 *                 of struct @spi_transfer)
 * @gfp:           gfp flags
 *
 * Returns: pointer to @spi_replaced_transfers,
 *          PTR_ERR(...) in case of errors.
 */
struct spi_replaced_transfers *spi_replace_transfers(
        struct spi_message *msg,
        struct spi_transfer *xfer_first,
        size_t remove,
        size_t insert,
        spi_replaced_release_t release,
        size_t extradatasize,
        gfp_t gfp)
{
        struct spi_replaced_transfers *rxfer;
        struct spi_transfer *xfer;
        size_t i;

        /* allocate the structure using spi_res */
        rxfer = spi_res_alloc(msg->spi, __spi_replace_transfers_release,
                              struct_size(rxfer, inserted_transfers, insert)
                              + extradatasize,
                              gfp);
        if (!rxfer)
                return ERR_PTR(-ENOMEM);

        /* the release code to invoke before running the generic release */
        rxfer->release = release;

        /* assign extradata */
        if (extradatasize)
                rxfer->extradata =
                        &rxfer->inserted_transfers[insert];

        /* init the replaced_transfers list */
        INIT_LIST_HEAD(&rxfer->replaced_transfers);

        /* assign the list_entry after which we should reinsert
         * the @replaced_transfers - it may be spi_message.messages!
         */
        rxfer->replaced_after = xfer_first->transfer_list.prev;

        /* remove the requested number of transfers */
        for (i = 0; i < remove; i++) {
                /* if the entry after replaced_after it is msg->transfers
                 * then we have been requested to remove more transfers
                 * than are in the list
                 */
                if (rxfer->replaced_after->next == &msg->transfers) {
                        dev_err(&msg->spi->dev,
                                "requested to remove more spi_transfers than are available\n");
                        /* insert replaced transfers back into the message */
                        list_splice(&rxfer->replaced_transfers,
                                    rxfer->replaced_after);

                        /* free the spi_replace_transfer structure */
                        spi_res_free(rxfer);

                        /* and return with an error */
                        return ERR_PTR(-EINVAL);
                }

                /* remove the entry after replaced_after from list of
                 * transfers and add it to list of replaced_transfers
                 */
                list_move_tail(rxfer->replaced_after->next,
                               &rxfer->replaced_transfers);
        }

        /* create copy of the given xfer with identical settings
         * based on the first transfer to get removed
         */
        for (i = 0; i < insert; i++) {
                /* we need to run in reverse order */
                xfer = &rxfer->inserted_transfers[insert - 1 - i];

                /* copy all spi_transfer data */
                memcpy(xfer, xfer_first, sizeof(*xfer));

                /* add to list */
                list_add(&xfer->transfer_list, rxfer->replaced_after);

                /* clear cs_change and delay for all but the last */
                if (i) {
                        xfer->cs_change = false;
                        xfer->delay_usecs = 0;
                        xfer->delay.value = 0;
                }
        }

        /* set up inserted */
        rxfer->inserted = insert;

        /* and register it with spi_res/spi_message */
        spi_res_add(msg, rxfer);

        return rxfer;
}
EXPORT_SYMBOL_GPL(spi_replace_transfers);

static int __spi_split_transfer_maxsize(struct spi_controller *ctlr,
                                        struct spi_message *msg,
                                        struct spi_transfer **xferp,
                                        size_t maxsize,
                                        gfp_t gfp)
{
        struct spi_transfer *xfer = *xferp, *xfers;
        struct spi_replaced_transfers *srt;
        size_t offset;
        size_t count, i;

        /* calculate how many we have to replace */
        count = DIV_ROUND_UP(xfer->len, maxsize);

        /* create replacement */
        srt = spi_replace_transfers(msg, xfer, 1, count, NULL, 0, gfp);
        if (IS_ERR(srt))
                return PTR_ERR(srt);
        xfers = srt->inserted_transfers;

        /* now handle each of those newly inserted spi_transfers
         * note that the replacements spi_transfers all are preset
         * to the same values as *xferp, so tx_buf, rx_buf and len
         * are all identical (as well as most others)
         * so we just have to fix up len and the pointers.
         *
         * this also includes support for the depreciated
         * spi_message.is_dma_mapped interface
         */

        /* the first transfer just needs the length modified, so we
         * run it outside the loop
         */
        xfers[0].len = min_t(size_t, maxsize, xfer[0].len);

        /* all the others need rx_buf/tx_buf also set */
        for (i = 1, offset = maxsize; i < count; offset += maxsize, i++) {
                /* update rx_buf, tx_buf and dma */
                if (xfers[i].rx_buf)
                        xfers[i].rx_buf += offset;
                if (xfers[i].rx_dma)
                        xfers[i].rx_dma += offset;
                if (xfers[i].tx_buf)
                        xfers[i].tx_buf += offset;
                if (xfers[i].tx_dma)
                        xfers[i].tx_dma += offset;

                /* update length */
                xfers[i].len = min(maxsize, xfers[i].len - offset);
        }

        /* we set up xferp to the last entry we have inserted,
         * so that we skip those already split transfers
         */
        *xferp = &xfers[count - 1];

        /* increment statistics counters */
        SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics,
                                       transfers_split_maxsize);
        SPI_STATISTICS_INCREMENT_FIELD(&msg->spi->statistics,
                                       transfers_split_maxsize);

        return 0;
}

/**
 * spi_split_tranfers_maxsize - split spi transfers into multiple transfers
 *                              when an individual transfer exceeds a
 *                              certain size
 * @ctlr:    the @spi_controller for this transfer
 * @msg:   the @spi_message to transform
 * @maxsize:  the maximum when to apply this
 * @gfp: GFP allocation flags
 *
 * Return: status of transformation
 */
int spi_split_transfers_maxsize(struct spi_controller *ctlr,
                                struct spi_message *msg,
                                size_t maxsize,
                                gfp_t gfp)
{
        struct spi_transfer *xfer;
        int ret;

        /* iterate over the transfer_list,
         * but note that xfer is advanced to the last transfer inserted
         * to avoid checking sizes again unnecessarily (also xfer does
         * potentiall belong to a different list by the time the
         * replacement has happened
         */
        list_for_each_entry(xfer, &msg->transfers, transfer_list) {
                if (xfer->len > maxsize) {
                        ret = __spi_split_transfer_maxsize(ctlr, msg, &xfer,
                                                           maxsize, gfp);
                        if (ret)
                                return ret;
                }
        }

        return 0;
}
EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize);

/*-------------------------------------------------------------------------*/

/* Core methods for SPI controller protocol drivers.  Some of the
 * other core methods are currently defined as inline functions.
 */

static int __spi_validate_bits_per_word(struct spi_controller *ctlr,
                                        u8 bits_per_word)
{
        if (ctlr->bits_per_word_mask) {
                /* Only 32 bits fit in the mask */
                if (bits_per_word > 32)
                        return -EINVAL;
                if (!(ctlr->bits_per_word_mask & SPI_BPW_MASK(bits_per_word)))
                        return -EINVAL;
        }

        return 0;
}

/**
 * spi_setup - setup SPI mode and clock rate
 * @spi: the device whose settings are being modified
 * Context: can sleep, and no requests are queued to the device
 *
 * SPI protocol drivers may need to update the transfer mode if the
 * device doesn't work with its default.  They may likewise need
 * to update clock rates or word sizes from initial values.  This function
 * changes those settings, and must be called from a context that can sleep.
 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
 * effect the next time the device is selected and data is transferred to
 * or from it.  When this function returns, the spi device is deselected.
 *
 * Note that this call will fail if the protocol driver specifies an option
 * that the underlying controller or its driver does not support.  For
 * example, not all hardware supports wire transfers using nine bit words,
 * LSB-first wire encoding, or active-high chipselects.
 *
 * Return: zero on success, else a negative error code.
 */
int spi_setup(struct spi_device *spi)
{
        unsigned        bad_bits, ugly_bits;
        int             status;

        /* check mode to prevent that DUAL and QUAD set at the same time
         */
        if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
                ((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
                dev_err(&spi->dev,
                "setup: can not select dual and quad at the same time\n");
                return -EINVAL;
        }
        /* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
         */
        if ((spi->mode & SPI_3WIRE) && (spi->mode &
                (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
                 SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL)))
                return -EINVAL;
        /* help drivers fail *cleanly* when they need options
         * that aren't supported with their current controller
         * SPI_CS_WORD has a fallback software implementation,
         * so it is ignored here.
         */
        bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD);
        /* nothing prevents from working with active-high CS in case if it
         * is driven by GPIO.
         */
        if (gpio_is_valid(spi->cs_gpio))
                bad_bits &= ~SPI_CS_HIGH;
        ugly_bits = bad_bits &
                    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
                     SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL);
        if (ugly_bits) {
                dev_warn(&spi->dev,
                         "setup: ignoring unsupported mode bits %x\n",
                         ugly_bits);
                spi->mode &= ~ugly_bits;
                bad_bits &= ~ugly_bits;
        }
        if (bad_bits) {
                dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
                        bad_bits);
                return -EINVAL;
        }

        if (!spi->bits_per_word)
                spi->bits_per_word = 8;

        status = __spi_validate_bits_per_word(spi->controller,
                                              spi->bits_per_word);
        if (status)
                return status;

        if (!spi->max_speed_hz)
                spi->max_speed_hz = spi->controller->max_speed_hz;

        if (spi->controller->setup)
                status = spi->controller->setup(spi);

        if (spi->controller->auto_runtime_pm && spi->controller->set_cs) {
                status = pm_runtime_get_sync(spi->controller->dev.parent);
                if (status < 0) {
                        pm_runtime_put_noidle(spi->controller->dev.parent);
                        dev_err(&spi->controller->dev, "Failed to power device: %d\n",
                                status);
                        return status;
                }

                /*
                 * We do not want to return positive value from pm_runtime_get,
                 * there are many instances of devices calling spi_setup() and
                 * checking for a non-zero return value instead of a negative
                 * return value.
                 */
                status = 0;

                spi_set_cs(spi, false);
                pm_runtime_mark_last_busy(spi->controller->dev.parent);
                pm_runtime_put_autosuspend(spi->controller->dev.parent);
        } else {
                spi_set_cs(spi, false);
        }

        if (spi->rt && !spi->controller->rt) {
                spi->controller->rt = true;
                spi_set_thread_rt(spi->controller);
        }

        dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
                        (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
                        (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
                        (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
                        (spi->mode & SPI_3WIRE) ? "3wire, " : "",
                        (spi->mode & SPI_LOOP) ? "loopback, " : "",
                        spi->bits_per_word, spi->max_speed_hz,
                        status);

        return status;
}
EXPORT_SYMBOL_GPL(spi_setup);

/**
 * spi_set_cs_timing - configure CS setup, hold, and inactive delays
 * @spi: the device that requires specific CS timing configuration
 * @setup: CS setup time specified via @spi_delay
 * @hold: CS hold time specified via @spi_delay
 * @inactive: CS inactive delay between transfers specified via @spi_delay
 *
 * Return: zero on success, else a negative error code.
 */
int spi_set_cs_timing(struct spi_device *spi, struct spi_delay *setup,
                      struct spi_delay *hold, struct spi_delay *inactive)
{
        size_t len;

        if (spi->controller->set_cs_timing)
                return spi->controller->set_cs_timing(spi, setup, hold,
                                                      inactive);

        if ((setup && setup->unit == SPI_DELAY_UNIT_SCK) ||
            (hold && hold->unit == SPI_DELAY_UNIT_SCK) ||
            (inactive && inactive->unit == SPI_DELAY_UNIT_SCK)) {
                dev_err(&spi->dev,
                        "Clock-cycle delays for CS not supported in SW mode\n");
                return -ENOTSUPP;
        }

        len = sizeof(struct spi_delay);

        /* copy delays to controller */
        if (setup)
                memcpy(&spi->controller->cs_setup, setup, len);
        else
                memset(&spi->controller->cs_setup, 0, len);

        if (hold)
                memcpy(&spi->controller->cs_hold, hold, len);
        else
                memset(&spi->controller->cs_hold, 0, len);

        if (inactive)
                memcpy(&spi->controller->cs_inactive, inactive, len);
        else
                memset(&spi->controller->cs_inactive, 0, len);

        return 0;
}
EXPORT_SYMBOL_GPL(spi_set_cs_timing);

static int _spi_xfer_word_delay_update(struct spi_transfer *xfer,
                                       struct spi_device *spi)
{
        int delay1, delay2;

        delay1 = spi_delay_to_ns(&xfer->word_delay, xfer);
        if (delay1 < 0)
                return delay1;

        delay2 = spi_delay_to_ns(&spi->word_delay, xfer);
        if (delay2 < 0)
                return delay2;

        if (delay1 < delay2)
                memcpy(&xfer->word_delay, &spi->word_delay,
                       sizeof(xfer->word_delay));

        return 0;
}

static int __spi_validate(struct spi_device *spi, struct spi_message *message)
{
        struct spi_controller *ctlr = spi->controller;
        struct spi_transfer *xfer;
        int w_size;

        if (list_empty(&message->transfers))
                return -EINVAL;

        /* If an SPI controller does not support toggling the CS line on each
         * transfer (indicated by the SPI_CS_WORD flag) or we are using a GPIO
         * for the CS line, we can emulate the CS-per-word hardware function by
         * splitting transfers into one-word transfers and ensuring that
         * cs_change is set for each transfer.
         */
        if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
                                          spi->cs_gpiod ||
                                          gpio_is_valid(spi->cs_gpio))) {
                size_t maxsize;
                int ret;

                maxsize = (spi->bits_per_word + 7) / 8;

                /* spi_split_transfers_maxsize() requires message->spi */
                message->spi = spi;

                ret = spi_split_transfers_maxsize(ctlr, message, maxsize,
                                                  GFP_KERNEL);
                if (ret)
                        return ret;

                list_for_each_entry(xfer, &message->transfers, transfer_list) {
                        /* don't change cs_change on the last entry in the list */
                        if (list_is_last(&xfer->transfer_list, &message->transfers))
                                break;
                        xfer->cs_change = 1;
                }
        }

        /* Half-duplex links include original MicroWire, and ones with
         * only one data pin like SPI_3WIRE (switches direction) or where
         * either MOSI or MISO is missing.  They can also be caused by
         * software limitations.
         */
        if ((ctlr->flags & SPI_CONTROLLER_HALF_DUPLEX) ||
            (spi->mode & SPI_3WIRE)) {
                unsigned flags = ctlr->flags;

                list_for_each_entry(xfer, &message->transfers, transfer_list) {
                        if (xfer->rx_buf && xfer->tx_buf)
                                return -EINVAL;
                        if ((flags & SPI_CONTROLLER_NO_TX) && xfer->tx_buf)
                                return -EINVAL;
                        if ((flags & SPI_CONTROLLER_NO_RX) && xfer->rx_buf)
                                return -EINVAL;
                }
        }

        /**
         * Set transfer bits_per_word and max speed as spi device default if
         * it is not set for this transfer.
         * Set transfer tx_nbits and rx_nbits as single transfer default
         * (SPI_NBITS_SINGLE) if it is not set for this transfer.
         * Ensure transfer word_delay is at least as long as that required by
         * device itself.
         */
        message->frame_length = 0;
        list_for_each_entry(xfer, &message->transfers, transfer_list) {
                xfer->effective_speed_hz = 0;
                message->frame_length += xfer->len;
                if (!xfer->bits_per_word)
                        xfer->bits_per_word = spi->bits_per_word;

                if (!xfer->speed_hz)
                        xfer->speed_hz = spi->max_speed_hz;

                if (ctlr->max_speed_hz && xfer->speed_hz > ctlr->max_speed_hz)
                        xfer->speed_hz = ctlr->max_speed_hz;

                if (__spi_validate_bits_per_word(ctlr, xfer->bits_per_word))
                        return -EINVAL;

                /*
                 * SPI transfer length should be multiple of SPI word size
                 * where SPI word size should be power-of-two multiple
                 */
                if (xfer->bits_per_word <= 8)
                        w_size = 1;
                else if (xfer->bits_per_word <= 16)
                        w_size = 2;
                else
                        w_size = 4;

                /* No partial transfers accepted */
                if (xfer->len % w_size)
                        return -EINVAL;

                if (xfer->speed_hz && ctlr->min_speed_hz &&
                    xfer->speed_hz < ctlr->min_speed_hz)
                        return -EINVAL;

                if (xfer->tx_buf && !xfer->tx_nbits)
                        xfer->tx_nbits = SPI_NBITS_SINGLE;
                if (xfer->rx_buf && !xfer->rx_nbits)
                        xfer->rx_nbits = SPI_NBITS_SINGLE;
                /* check transfer tx/rx_nbits:
                 * 1. check the value matches one of single, dual and quad
                 * 2. check tx/rx_nbits match the mode in spi_device
                 */
                if (xfer->tx_buf) {
                        if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
                                xfer->tx_nbits != SPI_NBITS_DUAL &&
                                xfer->tx_nbits != SPI_NBITS_QUAD)
                                return -EINVAL;
                        if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
                                !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
                                return -EINVAL;
                        if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
                                !(spi->mode & SPI_TX_QUAD))
                                return -EINVAL;
                }
                /* check transfer rx_nbits */
                if (xfer->rx_buf) {
                        if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
                                xfer->rx_nbits != SPI_NBITS_DUAL &&
                                xfer->rx_nbits != SPI_NBITS_QUAD)
                                return -EINVAL;
                        if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
                                !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
                                return -EINVAL;
                        if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
                                !(spi->mode & SPI_RX_QUAD))
                                return -EINVAL;
                }

                if (_spi_xfer_word_delay_update(xfer, spi))
                        return -EINVAL;
        }

        message->status = -EINPROGRESS;

        return 0;
}

static int __spi_async(struct spi_device *spi, struct spi_message *message)
{
        struct spi_controller *ctlr = spi->controller;
        struct spi_transfer *xfer;

        /*
         * Some controllers do not support doing regular SPI transfers. Return
         * ENOTSUPP when this is the case.
         */
        if (!ctlr->transfer)
                return -ENOTSUPP;

        message->spi = spi;

        SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics, spi_async);
        SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics, spi_async);

        trace_spi_message_submit(message);

        if (!ctlr->ptp_sts_supported) {
                list_for_each_entry(xfer, &message->transfers, transfer_list) {
                        xfer->ptp_sts_word_pre = 0;
                        ptp_read_system_prets(xfer->ptp_sts);
                }
        }

        return ctlr->transfer(spi, message);
}

/**
 * spi_async - asynchronous SPI transfer
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers, including completion callback
 * Context: any (irqs may be blocked, etc)
 *
 * This call may be used in_irq and other contexts which can't sleep,
 * as well as from task contexts which can sleep.
 *
 * The completion callback is invoked in a context which can't sleep.
 * Before that invocation, the value of message->status is undefined.
 * When the callback is issued, message->status holds either zero (to
 * indicate complete success) or a negative error code.  After that
 * callback returns, the driver which issued the transfer request may
 * deallocate the associated memory; it's no longer in use by any SPI
 * core or controller driver code.
 *
 * Note that although all messages to a spi_device are handled in
 * FIFO order, messages may go to different devices in other orders.
 * Some device might be higher priority, or have various "hard" access
 * time requirements, for example.
 *
 * On detection of any fault during the transfer, processing of
 * the entire message is aborted, and the device is deselected.
 * Until returning from the associated message completion callback,
 * no other spi_message queued to that device will be processed.
 * (This rule applies equally to all the synchronous transfer calls,
 * which are wrappers around this core asynchronous primitive.)
 *
 * Return: zero on success, else a negative error code.
 */
int spi_async(struct spi_device *spi, struct spi_message *message)
{
        struct spi_controller *ctlr = spi->controller;
        int ret;
        unsigned long flags;

        ret = __spi_validate(spi, message);
        if (ret != 0)
                return ret;

        spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);

        if (ctlr->bus_lock_flag)
                ret = -EBUSY;
        else
                ret = __spi_async(spi, message);

        spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);

        return ret;
}
EXPORT_SYMBOL_GPL(spi_async);

/**
 * spi_async_locked - version of spi_async with exclusive bus usage
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers, including completion callback
 * Context: any (irqs may be blocked, etc)
 *
 * This call may be used in_irq and other contexts which can't sleep,
 * as well as from task contexts which can sleep.
 *
 * The completion callback is invoked in a context which can't sleep.
 * Before that invocation, the value of message->status is undefined.
 * When the callback is issued, message->status holds either zero (to
 * indicate complete success) or a negative error code.  After that
 * callback returns, the driver which issued the transfer request may
 * deallocate the associated memory; it's no longer in use by any SPI
 * core or controller driver code.
 *
 * Note that although all messages to a spi_device are handled in
 * FIFO order, messages may go to different devices in other orders.
 * Some device might be higher priority, or have various "hard" access
 * time requirements, for example.
 *
 * On detection of any fault during the transfer, processing of
 * the entire message is aborted, and the device is deselected.
 * Until returning from the associated message completion callback,
 * no other spi_message queued to that device will be processed.
 * (This rule applies equally to all the synchronous transfer calls,
 * which are wrappers around this core asynchronous primitive.)
 *
 * Return: zero on success, else a negative error code.
 */
int spi_async_locked(struct spi_device *spi, struct spi_message *message)
{
        struct spi_controller *ctlr = spi->controller;
        int ret;
        unsigned long flags;

        ret = __spi_validate(spi, message);
        if (ret != 0)
                return ret;

        spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);

        ret = __spi_async(spi, message);

        spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);

        return ret;

}
EXPORT_SYMBOL_GPL(spi_async_locked);

/*-------------------------------------------------------------------------*/

/* Utility methods for SPI protocol drivers, layered on
 * top of the core.  Some other utility methods are defined as
 * inline functions.
 */

static void spi_complete(void *arg)
{
        complete(arg);
}

static int __spi_sync(struct spi_device *spi, struct spi_message *message)
{
        DECLARE_COMPLETION_ONSTACK(done);
        int status;
        struct spi_controller *ctlr = spi->controller;
        unsigned long flags;

        status = __spi_validate(spi, message);
        if (status != 0)
                return status;

        message->complete = spi_complete;
        message->context = &done;
        message->spi = spi;

        SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics, spi_sync);
        SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics, spi_sync);

        /* If we're not using the legacy transfer method then we will
         * try to transfer in the calling context so special case.
         * This code would be less tricky if we could remove the
         * support for driver implemented message queues.
         */
        if (ctlr->transfer == spi_queued_transfer) {
                spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);

                trace_spi_message_submit(message);

                status = __spi_queued_transfer(spi, message, false);

                spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
        } else {
                status = spi_async_locked(spi, message);
        }

        if (status == 0) {
                /* Push out the messages in the calling context if we
                 * can.
                 */
                if (ctlr->transfer == spi_queued_transfer) {
                        SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics,
                                                       spi_sync_immediate);
                        SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics,
                                                       spi_sync_immediate);
                        __spi_pump_messages(ctlr, false);
                }

                wait_for_completion(&done);
                status = message->status;
        }
        message->context = NULL;
        return status;
}

/**
 * spi_sync - blocking/synchronous SPI data transfers
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.  Low-overhead controller
 * drivers may DMA directly into and out of the message buffers.
 *
 * Note that the SPI device's chip select is active during the message,
 * and then is normally disabled between messages.  Drivers for some
 * frequently-used devices may want to minimize costs of selecting a chip,
 * by leaving it selected in anticipation that the next message will go
 * to the same chip.  (That may increase power usage.)
 *
 * Also, the caller is guaranteeing that the memory associated with the
 * message will not be freed before this call returns.
 *
 * Return: zero on success, else a negative error code.
 */
int spi_sync(struct spi_device *spi, struct spi_message *message)
{
        int ret;

        mutex_lock(&spi->controller->bus_lock_mutex);
        ret = __spi_sync(spi, message);
        mutex_unlock(&spi->controller->bus_lock_mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(spi_sync);

/**
 * spi_sync_locked - version of spi_sync with exclusive bus usage
 * @spi: device with which data will be exchanged
 * @message: describes the data transfers
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.  Low-overhead controller
 * drivers may DMA directly into and out of the message buffers.
 *
 * This call should be used by drivers that require exclusive access to the
 * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
 * be released by a spi_bus_unlock call when the exclusive access is over.
 *
 * Return: zero on success, else a negative error code.
 */
int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
{
        return __spi_sync(spi, message);
}
EXPORT_SYMBOL_GPL(spi_sync_locked);

/**
 * spi_bus_lock - obtain a lock for exclusive SPI bus usage
 * @ctlr: SPI bus master that should be locked for exclusive bus access
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.
 *
 * This call should be used by drivers that require exclusive access to the
 * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
 * exclusive access is over. Data transfer must be done by spi_sync_locked
 * and spi_async_locked calls when the SPI bus lock is held.
 *
 * Return: always zero.
 */
int spi_bus_lock(struct spi_controller *ctlr)
{
        unsigned long flags;

        mutex_lock(&ctlr->bus_lock_mutex);

        spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
        ctlr->bus_lock_flag = 1;
        spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);

        /* mutex remains locked until spi_bus_unlock is called */

        return 0;
}
EXPORT_SYMBOL_GPL(spi_bus_lock);

/**
 * spi_bus_unlock - release the lock for exclusive SPI bus usage
 * @ctlr: SPI bus master that was locked for exclusive bus access
 * Context: can sleep
 *
 * This call may only be used from a context that may sleep.  The sleep
 * is non-interruptible, and has no timeout.
 *
 * This call releases an SPI bus lock previously obtained by an spi_bus_lock
 * call.
 *
 * Return: always zero.
 */
int spi_bus_unlock(struct spi_controller *ctlr)
{
        ctlr->bus_lock_flag = 0;

        mutex_unlock(&ctlr->bus_lock_mutex);

        return 0;
}
EXPORT_SYMBOL_GPL(spi_bus_unlock);

/* portable code must never pass more than 32 bytes */
#define SPI_BUFSIZ      max(32, SMP_CACHE_BYTES)

static u8       *buf;

/**
 * spi_write_then_read - SPI synchronous write followed by read
 * @spi: device with which data will be exchanged
 * @txbuf: data to be written (need not be dma-safe)
 * @n_tx: size of txbuf, in bytes
 * @rxbuf: buffer into which data will be read (need not be dma-safe)
 * @n_rx: size of rxbuf, in bytes
 * Context: can sleep
 *
 * This performs a half duplex MicroWire style transaction with the
 * device, sending txbuf and then reading rxbuf.  The return value
 * is zero for success, else a negative errno status code.
 * This call may only be used from a context that may sleep.
 *
 * Parameters to this routine are always copied using a small buffer.
 * Performance-sensitive or bulk transfer code should instead use
 * spi_{async,sync}() calls with dma-safe buffers.
 *
 * Return: zero on success, else a negative error code.
 */
int spi_write_then_read(struct spi_device *spi,
                const void *txbuf, unsigned n_tx,
                void *rxbuf, unsigned n_rx)
{
        static DEFINE_MUTEX(lock);

        int                     status;
        struct spi_message      message;
        struct spi_transfer     x[2];
        u8                      *local_buf;

        /* Use preallocated DMA-safe buffer if we can.  We can't avoid
         * copying here, (as a pure convenience thing), but we can
         * keep heap costs out of the hot path unless someone else is
         * using the pre-allocated buffer or the transfer is too large.
         */
        if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
                local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
                                    GFP_KERNEL | GFP_DMA);
                if (!local_buf)
                        return -ENOMEM;
        } else {
                local_buf = buf;
        }

        spi_message_init(&message);
        memset(x, 0, sizeof(x));
        if (n_tx) {
                x[0].len = n_tx;
                spi_message_add_tail(&x[0], &message);
        }
        if (n_rx) {
                x[1].len = n_rx;
                spi_message_add_tail(&x[1], &message);
        }

        memcpy(local_buf, txbuf, n_tx);
        x[0].tx_buf = local_buf;
        x[1].rx_buf = local_buf + n_tx;

        /* do the i/o */
        status = spi_sync(spi, &message);
        if (status == 0)
                memcpy(rxbuf, x[1].rx_buf, n_rx);

        if (x[0].tx_buf == buf)
                mutex_unlock(&lock);
        else
                kfree(local_buf);

        return status;
}
EXPORT_SYMBOL_GPL(spi_write_then_read);

/*-------------------------------------------------------------------------*/

#if IS_ENABLED(CONFIG_OF)
/* must call put_device() when done with returned spi_device device */
struct spi_device *of_find_spi_device_by_node(struct device_node *node)
{
        struct device *dev = bus_find_device_by_of_node(&spi_bus_type, node);

        return dev ? to_spi_device(dev) : NULL;
}
EXPORT_SYMBOL_GPL(of_find_spi_device_by_node);
#endif /* IS_ENABLED(CONFIG_OF) */

#if IS_ENABLED(CONFIG_OF_DYNAMIC)
/* the spi controllers are not using spi_bus, so we find it with another way */
static struct spi_controller *of_find_spi_controller_by_node(struct device_node *node)
{
        struct device *dev;

        dev = class_find_device_by_of_node(&spi_master_class, node);
        if (!dev && IS_ENABLED(CONFIG_SPI_SLAVE))
                dev = class_find_device_by_of_node(&spi_slave_class, node);
        if (!dev)
                return NULL;

        /* reference got in class_find_device */
        return container_of(dev, struct spi_controller, dev);
}

static int of_spi_notify(struct notifier_block *nb, unsigned long action,
                         void *arg)
{
        struct of_reconfig_data *rd = arg;
        struct spi_controller *ctlr;
        struct spi_device *spi;

        switch (of_reconfig_get_state_change(action, arg)) {
        case OF_RECONFIG_CHANGE_ADD:
                ctlr = of_find_spi_controller_by_node(rd->dn->parent);
                if (ctlr == NULL)
                        return NOTIFY_OK;       /* not for us */

                if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
                        put_device(&ctlr->dev);
                        return NOTIFY_OK;
                }

                spi = of_register_spi_device(ctlr, rd->dn);
                put_device(&ctlr->dev);

                if (IS_ERR(spi)) {
                        pr_err("%s: failed to create for '%pOF'\n",
                                        __func__, rd->dn);
                        of_node_clear_flag(rd->dn, OF_POPULATED);
                        return notifier_from_errno(PTR_ERR(spi));
                }
                break;

        case OF_RECONFIG_CHANGE_REMOVE:
                /* already depopulated? */
                if (!of_node_check_flag(rd->dn, OF_POPULATED))
                        return NOTIFY_OK;

                /* find our device by node */
                spi = of_find_spi_device_by_node(rd->dn);
                if (spi == NULL)
                        return NOTIFY_OK;       /* no? not meant for us */

                /* unregister takes one ref away */
                spi_unregister_device(spi);

                /* and put the reference of the find */
                put_device(&spi->dev);
                break;
        }

        return NOTIFY_OK;
}

static struct notifier_block spi_of_notifier = {
        .notifier_call = of_spi_notify,
};
#else /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
extern struct notifier_block spi_of_notifier;
#endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */

#if IS_ENABLED(CONFIG_ACPI)
static int spi_acpi_controller_match(struct device *dev, const void *data)
{
        return ACPI_COMPANION(dev->parent) == data;
}

static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev)
{
        struct device *dev;

        dev = class_find_device(&spi_master_class, NULL, adev,
                                spi_acpi_controller_match);
        if (!dev && IS_ENABLED(CONFIG_SPI_SLAVE))
                dev = class_find_device(&spi_slave_class, NULL, adev,
                                        spi_acpi_controller_match);
        if (!dev)
                return NULL;

        return container_of(dev, struct spi_controller, dev);
}

static struct spi_device *acpi_spi_find_device_by_adev(struct acpi_device *adev)
{
        struct device *dev;

        dev = bus_find_device_by_acpi_dev(&spi_bus_type, adev);
        return to_spi_device(dev);
}

static int acpi_spi_notify(struct notifier_block *nb, unsigned long value,
                           void *arg)
{
        struct acpi_device *adev = arg;
        struct spi_controller *ctlr;
        struct spi_device *spi;

        switch (value) {
        case ACPI_RECONFIG_DEVICE_ADD:
                ctlr = acpi_spi_find_controller_by_adev(adev->parent);
                if (!ctlr)
                        break;

                acpi_register_spi_device(ctlr, adev);
                put_device(&ctlr->dev);
                break;
        case ACPI_RECONFIG_DEVICE_REMOVE:
                if (!acpi_device_enumerated(adev))
                        break;

                spi = acpi_spi_find_device_by_adev(adev);
                if (!spi)
                        break;

                spi_unregister_device(spi);
                put_device(&spi->dev);
                break;
        }

        return NOTIFY_OK;
}

static struct notifier_block spi_acpi_notifier = {
        .notifier_call = acpi_spi_notify,
};
#else
extern struct notifier_block spi_acpi_notifier;
#endif

static int __init spi_init(void)
{
        int     status;

        buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
        if (!buf) {
                status = -ENOMEM;
                goto err0;
        }

        status = bus_register(&spi_bus_type);
        if (status < 0)
                goto err1;

        status = class_register(&spi_master_class);
        if (status < 0)
                goto err2;

        if (IS_ENABLED(CONFIG_SPI_SLAVE)) {
                status = class_register(&spi_slave_class);
                if (status < 0)
                        goto err3;
        }

        if (IS_ENABLED(CONFIG_OF_DYNAMIC))
                WARN_ON(of_reconfig_notifier_register(&spi_of_notifier));
        if (IS_ENABLED(CONFIG_ACPI))
                WARN_ON(acpi_reconfig_notifier_register(&spi_acpi_notifier));

        return 0;

err3:
        class_unregister(&spi_master_class);
err2:
        bus_unregister(&spi_bus_type);
err1:
        kfree(buf);
        buf = NULL;
err0:
        return status;
}

/* board_info is normally registered in arch_initcall(),
 * but even essential drivers wait till later
 *
 * REVISIT only boardinfo really needs static linking. the rest (device and
 * driver registration) _could_ be dynamically linked (modular) ... costs
 * include needing to have boardinfo data structures be much more public.
 */
postcore_initcall(spi_init);