spi/bfin_spi: push all size checks into the transfer function

[mirror_ubuntu-artful-kernel.git] / drivers / spi / spi_bfin5xx.c

/*
 * Blackfin On-Chip SPI Driver
 *
 * Copyright 2004-2007 Analog Devices Inc.
 *
 * Enter bugs at http://blackfin.uclinux.org/
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/spi/spi.h>
#include <linux/workqueue.h>

#include <asm/dma.h>
#include <asm/portmux.h>
#include <asm/bfin5xx_spi.h>
#include <asm/cacheflush.h>

#define DRV_NAME        "bfin-spi"
#define DRV_AUTHOR      "Bryan Wu, Luke Yang"
#define DRV_DESC        "Blackfin on-chip SPI Controller Driver"
#define DRV_VERSION     "1.0"

MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_LICENSE("GPL");

#define START_STATE     ((void *)0)
#define RUNNING_STATE   ((void *)1)
#define DONE_STATE      ((void *)2)
#define ERROR_STATE     ((void *)-1)

struct master_data;

struct transfer_ops {
        void (*write) (struct master_data *);
        void (*read) (struct master_data *);
        void (*duplex) (struct master_data *);
};

struct master_data {
        /* Driver model hookup */
        struct platform_device *pdev;

        /* SPI framework hookup */
        struct spi_master *master;

        /* Regs base of SPI controller */
        void __iomem *regs_base;

        /* Pin request list */
        u16 *pin_req;

        /* BFIN hookup */
        struct bfin5xx_spi_master *master_info;

        /* Driver message queue */
        struct workqueue_struct *workqueue;
        struct work_struct pump_messages;
        spinlock_t lock;
        struct list_head queue;
        int busy;
        bool running;

        /* Message Transfer pump */
        struct tasklet_struct pump_transfers;

        /* Current message transfer state info */
        struct spi_message *cur_msg;
        struct spi_transfer *cur_transfer;
        struct slave_data *cur_chip;
        size_t len_in_bytes;
        size_t len;
        void *tx;
        void *tx_end;
        void *rx;
        void *rx_end;

        /* DMA stuffs */
        int dma_channel;
        int dma_mapped;
        int dma_requested;
        dma_addr_t rx_dma;
        dma_addr_t tx_dma;

        int irq_requested;
        int spi_irq;

        size_t rx_map_len;
        size_t tx_map_len;
        u8 n_bytes;
        u16 ctrl_reg;
        u16 flag_reg;

        int cs_change;
        const struct transfer_ops *ops;
};

struct slave_data {
        u16 ctl_reg;
        u16 baud;
        u16 flag;

        u8 chip_select_num;
        u8 enable_dma;
        u16 cs_chg_udelay;      /* Some devices require > 255usec delay */
        u32 cs_gpio;
        u16 idle_tx_val;
        u8 pio_interrupt;       /* use spi data irq */
        const struct transfer_ops *ops;
};

#define DEFINE_SPI_REG(reg, off) \
static inline u16 read_##reg(struct master_data *drv_data) \
        { return bfin_read16(drv_data->regs_base + off); } \
static inline void write_##reg(struct master_data *drv_data, u16 v) \
        { bfin_write16(drv_data->regs_base + off, v); }

DEFINE_SPI_REG(CTRL, 0x00)
DEFINE_SPI_REG(FLAG, 0x04)
DEFINE_SPI_REG(STAT, 0x08)
DEFINE_SPI_REG(TDBR, 0x0C)
DEFINE_SPI_REG(RDBR, 0x10)
DEFINE_SPI_REG(BAUD, 0x14)
DEFINE_SPI_REG(SHAW, 0x18)

static void bfin_spi_enable(struct master_data *drv_data)
{
        u16 cr;

        cr = read_CTRL(drv_data);
        write_CTRL(drv_data, (cr | BIT_CTL_ENABLE));
}

static void bfin_spi_disable(struct master_data *drv_data)
{
        u16 cr;

        cr = read_CTRL(drv_data);
        write_CTRL(drv_data, (cr & (~BIT_CTL_ENABLE)));
}

/* Caculate the SPI_BAUD register value based on input HZ */
static u16 hz_to_spi_baud(u32 speed_hz)
{
        u_long sclk = get_sclk();
        u16 spi_baud = (sclk / (2 * speed_hz));

        if ((sclk % (2 * speed_hz)) > 0)
                spi_baud++;

        if (spi_baud < MIN_SPI_BAUD_VAL)
                spi_baud = MIN_SPI_BAUD_VAL;

        return spi_baud;
}

static int bfin_spi_flush(struct master_data *drv_data)
{
        unsigned long limit = loops_per_jiffy << 1;

        /* wait for stop and clear stat */
        while (!(read_STAT(drv_data) & BIT_STAT_SPIF) && --limit)
                cpu_relax();

        write_STAT(drv_data, BIT_STAT_CLR);

        return limit;
}

/* Chip select operation functions for cs_change flag */
static void bfin_spi_cs_active(struct master_data *drv_data, struct slave_data *chip)
{
        if (likely(chip->chip_select_num < MAX_CTRL_CS)) {
                u16 flag = read_FLAG(drv_data);

                flag &= ~chip->flag;

                write_FLAG(drv_data, flag);
        } else {
                gpio_set_value(chip->cs_gpio, 0);
        }
}

static void bfin_spi_cs_deactive(struct master_data *drv_data, struct slave_data *chip)
{
        if (likely(chip->chip_select_num < MAX_CTRL_CS)) {
                u16 flag = read_FLAG(drv_data);

                flag |= chip->flag;

                write_FLAG(drv_data, flag);
        } else {
                gpio_set_value(chip->cs_gpio, 1);
        }

        /* Move delay here for consistency */
        if (chip->cs_chg_udelay)
                udelay(chip->cs_chg_udelay);
}

/* enable or disable the pin muxed by GPIO and SPI CS to work as SPI CS */
static inline void bfin_spi_cs_enable(struct master_data *drv_data, struct slave_data *chip)
{
        if (chip->chip_select_num < MAX_CTRL_CS) {
                u16 flag = read_FLAG(drv_data);

                flag |= (chip->flag >> 8);

                write_FLAG(drv_data, flag);
        }
}

static inline void bfin_spi_cs_disable(struct master_data *drv_data, struct slave_data *chip)
{
        if (chip->chip_select_num < MAX_CTRL_CS) {
                u16 flag = read_FLAG(drv_data);

                flag &= ~(chip->flag >> 8);

                write_FLAG(drv_data, flag);
        }
}

/* stop controller and re-config current chip*/
static void bfin_spi_restore_state(struct master_data *drv_data)
{
        struct slave_data *chip = drv_data->cur_chip;

        /* Clear status and disable clock */
        write_STAT(drv_data, BIT_STAT_CLR);
        bfin_spi_disable(drv_data);
        dev_dbg(&drv_data->pdev->dev, "restoring spi ctl state\n");

        SSYNC();

        /* Load the registers */
        write_CTRL(drv_data, chip->ctl_reg);
        write_BAUD(drv_data, chip->baud);

        bfin_spi_enable(drv_data);
        bfin_spi_cs_active(drv_data, chip);
}

/* used to kick off transfer in rx mode and read unwanted RX data */
static inline void bfin_spi_dummy_read(struct master_data *drv_data)
{
        (void) read_RDBR(drv_data);
}

static void bfin_spi_u8_writer(struct master_data *drv_data)
{
        /* clear RXS (we check for RXS inside the loop) */
        bfin_spi_dummy_read(drv_data);

        while (drv_data->tx < drv_data->tx_end) {
                write_TDBR(drv_data, (*(u8 *) (drv_data->tx++)));
                /* wait until transfer finished.
                   checking SPIF or TXS may not guarantee transfer completion */
                while (!(read_STAT(drv_data) & BIT_STAT_RXS))
                        cpu_relax();
                /* discard RX data and clear RXS */
                bfin_spi_dummy_read(drv_data);
        }
}

static void bfin_spi_u8_reader(struct master_data *drv_data)
{
        u16 tx_val = drv_data->cur_chip->idle_tx_val;

        /* discard old RX data and clear RXS */
        bfin_spi_dummy_read(drv_data);

        while (drv_data->rx < drv_data->rx_end) {
                write_TDBR(drv_data, tx_val);
                while (!(read_STAT(drv_data) & BIT_STAT_RXS))
                        cpu_relax();
                *(u8 *) (drv_data->rx++) = read_RDBR(drv_data);
        }
}

static void bfin_spi_u8_duplex(struct master_data *drv_data)
{
        /* discard old RX data and clear RXS */
        bfin_spi_dummy_read(drv_data);

        while (drv_data->rx < drv_data->rx_end) {
                write_TDBR(drv_data, (*(u8 *) (drv_data->tx++)));
                while (!(read_STAT(drv_data) & BIT_STAT_RXS))
                        cpu_relax();
                *(u8 *) (drv_data->rx++) = read_RDBR(drv_data);
        }
}

static const struct transfer_ops bfin_transfer_ops_u8 = {
        .write  = bfin_spi_u8_writer,
        .read   = bfin_spi_u8_reader,
        .duplex = bfin_spi_u8_duplex,
};

static void bfin_spi_u16_writer(struct master_data *drv_data)
{
        /* clear RXS (we check for RXS inside the loop) */
        bfin_spi_dummy_read(drv_data);

        while (drv_data->tx < drv_data->tx_end) {
                write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
                drv_data->tx += 2;
                /* wait until transfer finished.
                   checking SPIF or TXS may not guarantee transfer completion */
                while (!(read_STAT(drv_data) & BIT_STAT_RXS))
                        cpu_relax();
                /* discard RX data and clear RXS */
                bfin_spi_dummy_read(drv_data);
        }
}

static void bfin_spi_u16_reader(struct master_data *drv_data)
{
        u16 tx_val = drv_data->cur_chip->idle_tx_val;

        /* discard old RX data and clear RXS */
        bfin_spi_dummy_read(drv_data);

        while (drv_data->rx < drv_data->rx_end) {
                write_TDBR(drv_data, tx_val);
                while (!(read_STAT(drv_data) & BIT_STAT_RXS))
                        cpu_relax();
                *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
                drv_data->rx += 2;
        }
}

static void bfin_spi_u16_duplex(struct master_data *drv_data)
{
        /* discard old RX data and clear RXS */
        bfin_spi_dummy_read(drv_data);

        while (drv_data->rx < drv_data->rx_end) {
                write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
                drv_data->tx += 2;
                while (!(read_STAT(drv_data) & BIT_STAT_RXS))
                        cpu_relax();
                *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
                drv_data->rx += 2;
        }
}

static const struct transfer_ops bfin_transfer_ops_u16 = {
        .write  = bfin_spi_u16_writer,
        .read   = bfin_spi_u16_reader,
        .duplex = bfin_spi_u16_duplex,
};

/* test if ther is more transfer to be done */
static void *bfin_spi_next_transfer(struct master_data *drv_data)
{
        struct spi_message *msg = drv_data->cur_msg;
        struct spi_transfer *trans = drv_data->cur_transfer;

        /* Move to next transfer */
        if (trans->transfer_list.next != &msg->transfers) {
                drv_data->cur_transfer =
                    list_entry(trans->transfer_list.next,
                               struct spi_transfer, transfer_list);
                return RUNNING_STATE;
        } else
                return DONE_STATE;
}

/*
 * caller already set message->status;
 * dma and pio irqs are blocked give finished message back
 */
static void bfin_spi_giveback(struct master_data *drv_data)
{
        struct slave_data *chip = drv_data->cur_chip;
        struct spi_transfer *last_transfer;
        unsigned long flags;
        struct spi_message *msg;

        spin_lock_irqsave(&drv_data->lock, flags);
        msg = drv_data->cur_msg;
        drv_data->cur_msg = NULL;
        drv_data->cur_transfer = NULL;
        drv_data->cur_chip = NULL;
        queue_work(drv_data->workqueue, &drv_data->pump_messages);
        spin_unlock_irqrestore(&drv_data->lock, flags);

        last_transfer = list_entry(msg->transfers.prev,
                                   struct spi_transfer, transfer_list);

        msg->state = NULL;

        if (!drv_data->cs_change)
                bfin_spi_cs_deactive(drv_data, chip);

        /* Not stop spi in autobuffer mode */
        if (drv_data->tx_dma != 0xFFFF)
                bfin_spi_disable(drv_data);

        if (msg->complete)
                msg->complete(msg->context);
}

/* spi data irq handler */
static irqreturn_t bfin_spi_pio_irq_handler(int irq, void *dev_id)
{
        struct master_data *drv_data = dev_id;
        struct slave_data *chip = drv_data->cur_chip;
        struct spi_message *msg = drv_data->cur_msg;
        int n_bytes = drv_data->n_bytes;

        /* wait until transfer finished. */
        while (!(read_STAT(drv_data) & BIT_STAT_RXS))
                cpu_relax();

        if ((drv_data->tx && drv_data->tx >= drv_data->tx_end) ||
                (drv_data->rx && drv_data->rx >= (drv_data->rx_end - n_bytes))) {
                /* last read */
                if (drv_data->rx) {
                        dev_dbg(&drv_data->pdev->dev, "last read\n");
                        if (n_bytes == 2)
                                *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
                        else if (n_bytes == 1)
                                *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
                        drv_data->rx += n_bytes;
                }

                msg->actual_length += drv_data->len_in_bytes;
                if (drv_data->cs_change)
                        bfin_spi_cs_deactive(drv_data, chip);
                /* Move to next transfer */
                msg->state = bfin_spi_next_transfer(drv_data);

                disable_irq_nosync(drv_data->spi_irq);

                /* Schedule transfer tasklet */
                tasklet_schedule(&drv_data->pump_transfers);
                return IRQ_HANDLED;
        }

        if (drv_data->rx && drv_data->tx) {
                /* duplex */
                dev_dbg(&drv_data->pdev->dev, "duplex: write_TDBR\n");
                if (drv_data->n_bytes == 2) {
                        *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
                        write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
                } else if (drv_data->n_bytes == 1) {
                        *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
                        write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
                }
        } else if (drv_data->rx) {
                /* read */
                dev_dbg(&drv_data->pdev->dev, "read: write_TDBR\n");
                if (drv_data->n_bytes == 2)
                        *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
                else if (drv_data->n_bytes == 1)
                        *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
                write_TDBR(drv_data, chip->idle_tx_val);
        } else if (drv_data->tx) {
                /* write */
                dev_dbg(&drv_data->pdev->dev, "write: write_TDBR\n");
                bfin_spi_dummy_read(drv_data);
                if (drv_data->n_bytes == 2)
                        write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
                else if (drv_data->n_bytes == 1)
                        write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
        }

        if (drv_data->tx)
                drv_data->tx += n_bytes;
        if (drv_data->rx)
                drv_data->rx += n_bytes;

        return IRQ_HANDLED;
}

static irqreturn_t bfin_spi_dma_irq_handler(int irq, void *dev_id)
{
        struct master_data *drv_data = dev_id;
        struct slave_data *chip = drv_data->cur_chip;
        struct spi_message *msg = drv_data->cur_msg;
        unsigned long timeout;
        unsigned short dmastat = get_dma_curr_irqstat(drv_data->dma_channel);
        u16 spistat = read_STAT(drv_data);

        dev_dbg(&drv_data->pdev->dev,
                "in dma_irq_handler dmastat:0x%x spistat:0x%x\n",
                dmastat, spistat);

        clear_dma_irqstat(drv_data->dma_channel);

        /*
         * wait for the last transaction shifted out.  HRM states:
         * at this point there may still be data in the SPI DMA FIFO waiting
         * to be transmitted ... software needs to poll TXS in the SPI_STAT
         * register until it goes low for 2 successive reads
         */
        if (drv_data->tx != NULL) {
                while ((read_STAT(drv_data) & BIT_STAT_TXS) ||
                       (read_STAT(drv_data) & BIT_STAT_TXS))
                        cpu_relax();
        }

        dev_dbg(&drv_data->pdev->dev,
                "in dma_irq_handler dmastat:0x%x spistat:0x%x\n",
                dmastat, read_STAT(drv_data));

        timeout = jiffies + HZ;
        while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
                if (!time_before(jiffies, timeout)) {
                        dev_warn(&drv_data->pdev->dev, "timeout waiting for SPIF");
                        break;
                } else
                        cpu_relax();

        if ((dmastat & DMA_ERR) && (spistat & BIT_STAT_RBSY)) {
                msg->state = ERROR_STATE;
                dev_err(&drv_data->pdev->dev, "dma receive: fifo/buffer overflow\n");
        } else {
                msg->actual_length += drv_data->len_in_bytes;

                if (drv_data->cs_change)
                        bfin_spi_cs_deactive(drv_data, chip);

                /* Move to next transfer */
                msg->state = bfin_spi_next_transfer(drv_data);
        }

        /* Schedule transfer tasklet */
        tasklet_schedule(&drv_data->pump_transfers);

        /* free the irq handler before next transfer */
        dev_dbg(&drv_data->pdev->dev,
                "disable dma channel irq%d\n",
                drv_data->dma_channel);
        dma_disable_irq(drv_data->dma_channel);

        return IRQ_HANDLED;
}

static void bfin_spi_pump_transfers(unsigned long data)
{
        struct master_data *drv_data = (struct master_data *)data;
        struct spi_message *message = NULL;
        struct spi_transfer *transfer = NULL;
        struct spi_transfer *previous = NULL;
        struct slave_data *chip = NULL;
        unsigned int bits_per_word;
        u8 width;
        u16 cr, dma_width, dma_config;
        u32 tranf_success = 1;
        u8 full_duplex = 0;

        /* Get current state information */
        message = drv_data->cur_msg;
        transfer = drv_data->cur_transfer;
        chip = drv_data->cur_chip;

        /*
         * if msg is error or done, report it back using complete() callback
         */

         /* Handle for abort */
        if (message->state == ERROR_STATE) {
                dev_dbg(&drv_data->pdev->dev, "transfer: we've hit an error\n");
                message->status = -EIO;
                bfin_spi_giveback(drv_data);
                return;
        }

        /* Handle end of message */
        if (message->state == DONE_STATE) {
                dev_dbg(&drv_data->pdev->dev, "transfer: all done!\n");
                message->status = 0;
                bfin_spi_giveback(drv_data);
                return;
        }

        /* Delay if requested at end of transfer */
        if (message->state == RUNNING_STATE) {
                dev_dbg(&drv_data->pdev->dev, "transfer: still running ...\n");
                previous = list_entry(transfer->transfer_list.prev,
                                      struct spi_transfer, transfer_list);
                if (previous->delay_usecs)
                        udelay(previous->delay_usecs);
        }

        /* Flush any existing transfers that may be sitting in the hardware */
        if (bfin_spi_flush(drv_data) == 0) {
                dev_err(&drv_data->pdev->dev, "pump_transfers: flush failed\n");
                message->status = -EIO;
                bfin_spi_giveback(drv_data);
                return;
        }

        if (transfer->len == 0) {
                /* Move to next transfer of this msg */
                message->state = bfin_spi_next_transfer(drv_data);
                /* Schedule next transfer tasklet */
                tasklet_schedule(&drv_data->pump_transfers);
        }

        if (transfer->tx_buf != NULL) {
                drv_data->tx = (void *)transfer->tx_buf;
                drv_data->tx_end = drv_data->tx + transfer->len;
                dev_dbg(&drv_data->pdev->dev, "tx_buf is %p, tx_end is %p\n",
                        transfer->tx_buf, drv_data->tx_end);
        } else {
                drv_data->tx = NULL;
        }

        if (transfer->rx_buf != NULL) {
                full_duplex = transfer->tx_buf != NULL;
                drv_data->rx = transfer->rx_buf;
                drv_data->rx_end = drv_data->rx + transfer->len;
                dev_dbg(&drv_data->pdev->dev, "rx_buf is %p, rx_end is %p\n",
                        transfer->rx_buf, drv_data->rx_end);
        } else {
                drv_data->rx = NULL;
        }

        drv_data->rx_dma = transfer->rx_dma;
        drv_data->tx_dma = transfer->tx_dma;
        drv_data->len_in_bytes = transfer->len;
        drv_data->cs_change = transfer->cs_change;

        /* Bits per word setup */
        bits_per_word = transfer->bits_per_word ? : message->spi->bits_per_word;
        if (bits_per_word == 8) {
                drv_data->n_bytes = 1;
                width = CFG_SPI_WORDSIZE8;
                drv_data->ops = &bfin_transfer_ops_u8;
        } else {
                drv_data->n_bytes = 2;
                width = CFG_SPI_WORDSIZE16;
                drv_data->ops = &bfin_transfer_ops_u16;
        }
        cr = (read_CTRL(drv_data) & (~BIT_CTL_TIMOD));
        cr |= (width << 8);
        write_CTRL(drv_data, cr);

        if (width == CFG_SPI_WORDSIZE16) {
                drv_data->len = (transfer->len) >> 1;
        } else {
                drv_data->len = transfer->len;
        }
        dev_dbg(&drv_data->pdev->dev,
                "transfer: drv_data->ops is %p, chip->ops is %p, u8_ops is %p\n",
                drv_data->ops, chip->ops, &bfin_transfer_ops_u8);

        message->state = RUNNING_STATE;
        dma_config = 0;

        /* Speed setup (surely valid because already checked) */
        if (transfer->speed_hz)
                write_BAUD(drv_data, hz_to_spi_baud(transfer->speed_hz));
        else
                write_BAUD(drv_data, chip->baud);

        write_STAT(drv_data, BIT_STAT_CLR);
        cr = (read_CTRL(drv_data) & (~BIT_CTL_TIMOD));
        if (drv_data->cs_change)
                bfin_spi_cs_active(drv_data, chip);

        dev_dbg(&drv_data->pdev->dev,
                "now pumping a transfer: width is %d, len is %d\n",
                width, transfer->len);

        /*
         * Try to map dma buffer and do a dma transfer.  If successful use,
         * different way to r/w according to the enable_dma settings and if
         * we are not doing a full duplex transfer (since the hardware does
         * not support full duplex DMA transfers).
         */
        if (!full_duplex && drv_data->cur_chip->enable_dma
                                && drv_data->len > 6) {

                unsigned long dma_start_addr, flags;

                disable_dma(drv_data->dma_channel);
                clear_dma_irqstat(drv_data->dma_channel);

                /* config dma channel */
                dev_dbg(&drv_data->pdev->dev, "doing dma transfer\n");
                set_dma_x_count(drv_data->dma_channel, drv_data->len);
                if (width == CFG_SPI_WORDSIZE16) {
                        set_dma_x_modify(drv_data->dma_channel, 2);
                        dma_width = WDSIZE_16;
                } else {
                        set_dma_x_modify(drv_data->dma_channel, 1);
                        dma_width = WDSIZE_8;
                }

                /* poll for SPI completion before start */
                while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
                        cpu_relax();

                /* dirty hack for autobuffer DMA mode */
                if (drv_data->tx_dma == 0xFFFF) {
                        dev_dbg(&drv_data->pdev->dev,
                                "doing autobuffer DMA out.\n");

                        /* no irq in autobuffer mode */
                        dma_config =
                            (DMAFLOW_AUTO | RESTART | dma_width | DI_EN);
                        set_dma_config(drv_data->dma_channel, dma_config);
                        set_dma_start_addr(drv_data->dma_channel,
                                        (unsigned long)drv_data->tx);
                        enable_dma(drv_data->dma_channel);

                        /* start SPI transfer */
                        write_CTRL(drv_data, cr | BIT_CTL_TIMOD_DMA_TX);

                        /* just return here, there can only be one transfer
                         * in this mode
                         */
                        message->status = 0;
                        bfin_spi_giveback(drv_data);
                        return;
                }

                /* In dma mode, rx or tx must be NULL in one transfer */
                dma_config = (RESTART | dma_width | DI_EN);
                if (drv_data->rx != NULL) {
                        /* set transfer mode, and enable SPI */
                        dev_dbg(&drv_data->pdev->dev, "doing DMA in to %p (size %zx)\n",
                                drv_data->rx, drv_data->len_in_bytes);

                        /* invalidate caches, if needed */
                        if (bfin_addr_dcacheable((unsigned long) drv_data->rx))
                                invalidate_dcache_range((unsigned long) drv_data->rx,
                                                        (unsigned long) (drv_data->rx +
                                                        drv_data->len_in_bytes));

                        dma_config |= WNR;
                        dma_start_addr = (unsigned long)drv_data->rx;
                        cr |= BIT_CTL_TIMOD_DMA_RX | BIT_CTL_SENDOPT;

                } else if (drv_data->tx != NULL) {
                        dev_dbg(&drv_data->pdev->dev, "doing DMA out.\n");

                        /* flush caches, if needed */
                        if (bfin_addr_dcacheable((unsigned long) drv_data->tx))
                                flush_dcache_range((unsigned long) drv_data->tx,
                                                (unsigned long) (drv_data->tx +
                                                drv_data->len_in_bytes));

                        dma_start_addr = (unsigned long)drv_data->tx;
                        cr |= BIT_CTL_TIMOD_DMA_TX;

                } else
                        BUG();

                /* oh man, here there be monsters ... and i dont mean the
                 * fluffy cute ones from pixar, i mean the kind that'll eat
                 * your data, kick your dog, and love it all.  do *not* try
                 * and change these lines unless you (1) heavily test DMA
                 * with SPI flashes on a loaded system (e.g. ping floods),
                 * (2) know just how broken the DMA engine interaction with
                 * the SPI peripheral is, and (3) have someone else to blame
                 * when you screw it all up anyways.
                 */
                set_dma_start_addr(drv_data->dma_channel, dma_start_addr);
                set_dma_config(drv_data->dma_channel, dma_config);
                local_irq_save(flags);
                SSYNC();
                write_CTRL(drv_data, cr);
                enable_dma(drv_data->dma_channel);
                dma_enable_irq(drv_data->dma_channel);
                local_irq_restore(flags);

                return;
        }

        if (chip->pio_interrupt) {
                /* use write mode. spi irq should have been disabled */
                cr = (read_CTRL(drv_data) & (~BIT_CTL_TIMOD));
                write_CTRL(drv_data, (cr | CFG_SPI_WRITE));

                /* discard old RX data and clear RXS */
                bfin_spi_dummy_read(drv_data);

                /* start transfer */
                if (drv_data->tx == NULL)
                        write_TDBR(drv_data, chip->idle_tx_val);
                else {
                        if (bits_per_word == 8)
                                write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
                        else
                                write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
                        drv_data->tx += drv_data->n_bytes;
                }

                /* once TDBR is empty, interrupt is triggered */
                enable_irq(drv_data->spi_irq);
                return;
        }

        /* IO mode */
        dev_dbg(&drv_data->pdev->dev, "doing IO transfer\n");

        /* we always use SPI_WRITE mode. SPI_READ mode
           seems to have problems with setting up the
           output value in TDBR prior to the transfer. */
        write_CTRL(drv_data, (cr | CFG_SPI_WRITE));

        if (full_duplex) {
                /* full duplex mode */
                BUG_ON((drv_data->tx_end - drv_data->tx) !=
                       (drv_data->rx_end - drv_data->rx));
                dev_dbg(&drv_data->pdev->dev,
                        "IO duplex: cr is 0x%x\n", cr);

                drv_data->ops->duplex(drv_data);

                if (drv_data->tx != drv_data->tx_end)
                        tranf_success = 0;
        } else if (drv_data->tx != NULL) {
                /* write only half duplex */
                dev_dbg(&drv_data->pdev->dev,
                        "IO write: cr is 0x%x\n", cr);

                drv_data->ops->write(drv_data);

                if (drv_data->tx != drv_data->tx_end)
                        tranf_success = 0;
        } else if (drv_data->rx != NULL) {
                /* read only half duplex */
                dev_dbg(&drv_data->pdev->dev,
                        "IO read: cr is 0x%x\n", cr);

                drv_data->ops->read(drv_data);
                if (drv_data->rx != drv_data->rx_end)
                        tranf_success = 0;
        }

        if (!tranf_success) {
                dev_dbg(&drv_data->pdev->dev,
                        "IO write error!\n");
                message->state = ERROR_STATE;
        } else {
                /* Update total byte transfered */
                message->actual_length += drv_data->len_in_bytes;
                /* Move to next transfer of this msg */
                message->state = bfin_spi_next_transfer(drv_data);
                if (drv_data->cs_change)
                        bfin_spi_cs_deactive(drv_data, chip);
        }

        /* Schedule next transfer tasklet */
        tasklet_schedule(&drv_data->pump_transfers);
}

/* pop a msg from queue and kick off real transfer */
static void bfin_spi_pump_messages(struct work_struct *work)
{
        struct master_data *drv_data;
        unsigned long flags;

        drv_data = container_of(work, struct master_data, pump_messages);

        /* Lock queue and check for queue work */
        spin_lock_irqsave(&drv_data->lock, flags);
        if (list_empty(&drv_data->queue) || !drv_data->running) {
                /* pumper kicked off but no work to do */
                drv_data->busy = 0;
                spin_unlock_irqrestore(&drv_data->lock, flags);
                return;
        }

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

        /* Extract head of queue */
        drv_data->cur_msg = list_entry(drv_data->queue.next,
                                       struct spi_message, queue);

        /* Setup the SSP using the per chip configuration */
        drv_data->cur_chip = spi_get_ctldata(drv_data->cur_msg->spi);
        bfin_spi_restore_state(drv_data);

        list_del_init(&drv_data->cur_msg->queue);

        /* Initial message state */
        drv_data->cur_msg->state = START_STATE;
        drv_data->cur_transfer = list_entry(drv_data->cur_msg->transfers.next,
                                            struct spi_transfer, transfer_list);

        dev_dbg(&drv_data->pdev->dev, "got a message to pump, "
                "state is set to: baud %d, flag 0x%x, ctl 0x%x\n",
                drv_data->cur_chip->baud, drv_data->cur_chip->flag,
                drv_data->cur_chip->ctl_reg);

        dev_dbg(&drv_data->pdev->dev,
                "the first transfer len is %d\n",
                drv_data->cur_transfer->len);

        /* Mark as busy and launch transfers */
        tasklet_schedule(&drv_data->pump_transfers);

        drv_data->busy = 1;
        spin_unlock_irqrestore(&drv_data->lock, flags);
}

/*
 * got a msg to transfer, queue it in drv_data->queue.
 * And kick off message pumper
 */
static int bfin_spi_transfer(struct spi_device *spi, struct spi_message *msg)
{
        struct master_data *drv_data = spi_master_get_devdata(spi->master);
        unsigned long flags;

        spin_lock_irqsave(&drv_data->lock, flags);

        if (!drv_data->running) {
                spin_unlock_irqrestore(&drv_data->lock, flags);
                return -ESHUTDOWN;
        }

        msg->actual_length = 0;
        msg->status = -EINPROGRESS;
        msg->state = START_STATE;

        dev_dbg(&spi->dev, "adding an msg in transfer() \n");
        list_add_tail(&msg->queue, &drv_data->queue);

        if (drv_data->running && !drv_data->busy)
                queue_work(drv_data->workqueue, &drv_data->pump_messages);

        spin_unlock_irqrestore(&drv_data->lock, flags);

        return 0;
}

#define MAX_SPI_SSEL    7

static u16 ssel[][MAX_SPI_SSEL] = {
        {P_SPI0_SSEL1, P_SPI0_SSEL2, P_SPI0_SSEL3,
        P_SPI0_SSEL4, P_SPI0_SSEL5,
        P_SPI0_SSEL6, P_SPI0_SSEL7},

        {P_SPI1_SSEL1, P_SPI1_SSEL2, P_SPI1_SSEL3,
        P_SPI1_SSEL4, P_SPI1_SSEL5,
        P_SPI1_SSEL6, P_SPI1_SSEL7},

        {P_SPI2_SSEL1, P_SPI2_SSEL2, P_SPI2_SSEL3,
        P_SPI2_SSEL4, P_SPI2_SSEL5,
        P_SPI2_SSEL6, P_SPI2_SSEL7},
};

/* setup for devices (may be called multiple times -- not just first setup) */
static int bfin_spi_setup(struct spi_device *spi)
{
        struct bfin5xx_spi_chip *chip_info;
        struct slave_data *chip = NULL;
        struct master_data *drv_data = spi_master_get_devdata(spi->master);
        int ret = -EINVAL;

        /* Only alloc (or use chip_info) on first setup */
        chip_info = NULL;
        chip = spi_get_ctldata(spi);
        if (chip == NULL) {
                chip = kzalloc(sizeof(*chip), GFP_KERNEL);
                if (!chip) {
                        dev_err(&spi->dev, "cannot allocate chip data\n");
                        ret = -ENOMEM;
                        goto error;
                }

                chip->enable_dma = 0;
                chip_info = spi->controller_data;
        }

        /* chip_info isn't always needed */
        if (chip_info) {
                /* Make sure people stop trying to set fields via ctl_reg
                 * when they should actually be using common SPI framework.
                 * Currently we let through: WOM EMISO PSSE GM SZ.
                 * Not sure if a user actually needs/uses any of these,
                 * but let's assume (for now) they do.
                 */
                if (chip_info->ctl_reg & ~(BIT_CTL_OPENDRAIN | BIT_CTL_EMISO | \
                                           BIT_CTL_PSSE | BIT_CTL_GM | BIT_CTL_SZ)) {
                        dev_err(&spi->dev, "do not set bits in ctl_reg "
                                "that the SPI framework manages\n");
                        goto error;
                }

                chip->enable_dma = chip_info->enable_dma != 0
                    && drv_data->master_info->enable_dma;
                chip->ctl_reg = chip_info->ctl_reg;
                chip->cs_chg_udelay = chip_info->cs_chg_udelay;
                chip->idle_tx_val = chip_info->idle_tx_val;
                chip->pio_interrupt = chip_info->pio_interrupt;
                spi->bits_per_word = chip_info->bits_per_word;
        }

        if (spi->bits_per_word != 8 && spi->bits_per_word != 16) {
                dev_err(&spi->dev, "%d bits_per_word is not supported\n",
                                spi->bits_per_word);
                goto error;
        }

        /* translate common spi framework into our register */
        if (spi->mode & SPI_CPOL)
                chip->ctl_reg |= BIT_CTL_CPOL;
        if (spi->mode & SPI_CPHA)
                chip->ctl_reg |= BIT_CTL_CPHA;
        if (spi->mode & SPI_LSB_FIRST)
                chip->ctl_reg |= BIT_CTL_LSBF;
        /* we dont support running in slave mode (yet?) */
        chip->ctl_reg |= BIT_CTL_MASTER;

        /*
         * Notice: for blackfin, the speed_hz is the value of register
         * SPI_BAUD, not the real baudrate
         */
        chip->baud = hz_to_spi_baud(spi->max_speed_hz);
        chip->chip_select_num = spi->chip_select;
        if (chip->chip_select_num < MAX_CTRL_CS)
                chip->flag = (1 << spi->chip_select) << 8;
        else
                chip->cs_gpio = chip->chip_select_num - MAX_CTRL_CS;

        if (chip->enable_dma && chip->pio_interrupt) {
                dev_err(&spi->dev, "enable_dma is set, "
                                "do not set pio_interrupt\n");
                goto error;
        }
        /*
         * if any one SPI chip is registered and wants DMA, request the
         * DMA channel for it
         */
        if (chip->enable_dma && !drv_data->dma_requested) {
                /* register dma irq handler */
                ret = request_dma(drv_data->dma_channel, "BFIN_SPI_DMA");
                if (ret) {
                        dev_err(&spi->dev,
                                "Unable to request BlackFin SPI DMA channel\n");
                        goto error;
                }
                drv_data->dma_requested = 1;

                ret = set_dma_callback(drv_data->dma_channel,
                        bfin_spi_dma_irq_handler, drv_data);
                if (ret) {
                        dev_err(&spi->dev, "Unable to set dma callback\n");
                        goto error;
                }
                dma_disable_irq(drv_data->dma_channel);
        }

        if (chip->pio_interrupt && !drv_data->irq_requested) {
                ret = request_irq(drv_data->spi_irq, bfin_spi_pio_irq_handler,
                        IRQF_DISABLED, "BFIN_SPI", drv_data);
                if (ret) {
                        dev_err(&spi->dev, "Unable to register spi IRQ\n");
                        goto error;
                }
                drv_data->irq_requested = 1;
                /* we use write mode, spi irq has to be disabled here */
                disable_irq(drv_data->spi_irq);
        }

        if (chip->chip_select_num >= MAX_CTRL_CS) {
                ret = gpio_request(chip->cs_gpio, spi->modalias);
                if (ret) {
                        dev_err(&spi->dev, "gpio_request() error\n");
                        goto pin_error;
                }
                gpio_direction_output(chip->cs_gpio, 1);
        }

        dev_dbg(&spi->dev, "setup spi chip %s, width is %d, dma is %d\n",
                        spi->modalias, spi->bits_per_word, chip->enable_dma);
        dev_dbg(&spi->dev, "ctl_reg is 0x%x, flag_reg is 0x%x\n",
                        chip->ctl_reg, chip->flag);

        spi_set_ctldata(spi, chip);

        dev_dbg(&spi->dev, "chip select number is %d\n", chip->chip_select_num);
        if (chip->chip_select_num < MAX_CTRL_CS) {
                ret = peripheral_request(ssel[spi->master->bus_num]
                                         [chip->chip_select_num-1], spi->modalias);
                if (ret) {
                        dev_err(&spi->dev, "peripheral_request() error\n");
                        goto pin_error;
                }
        }

        bfin_spi_cs_enable(drv_data, chip);
        bfin_spi_cs_deactive(drv_data, chip);

        return 0;

 pin_error:
        if (chip->chip_select_num >= MAX_CTRL_CS)
                gpio_free(chip->cs_gpio);
        else
                peripheral_free(ssel[spi->master->bus_num]
                        [chip->chip_select_num - 1]);
 error:
        if (chip) {
                if (drv_data->dma_requested)
                        free_dma(drv_data->dma_channel);
                drv_data->dma_requested = 0;

                kfree(chip);
                /* prevent free 'chip' twice */
                spi_set_ctldata(spi, NULL);
        }

        return ret;
}

/*
 * callback for spi framework.
 * clean driver specific data
 */
static void bfin_spi_cleanup(struct spi_device *spi)
{
        struct slave_data *chip = spi_get_ctldata(spi);
        struct master_data *drv_data = spi_master_get_devdata(spi->master);

        if (!chip)
                return;

        if (chip->chip_select_num < MAX_CTRL_CS) {
                peripheral_free(ssel[spi->master->bus_num]
                                        [chip->chip_select_num-1]);
                bfin_spi_cs_disable(drv_data, chip);
        } else
                gpio_free(chip->cs_gpio);

        kfree(chip);
        /* prevent free 'chip' twice */
        spi_set_ctldata(spi, NULL);
}

static inline int bfin_spi_init_queue(struct master_data *drv_data)
{
        INIT_LIST_HEAD(&drv_data->queue);
        spin_lock_init(&drv_data->lock);

        drv_data->running = false;
        drv_data->busy = 0;

        /* init transfer tasklet */
        tasklet_init(&drv_data->pump_transfers,
                     bfin_spi_pump_transfers, (unsigned long)drv_data);

        /* init messages workqueue */
        INIT_WORK(&drv_data->pump_messages, bfin_spi_pump_messages);
        drv_data->workqueue = create_singlethread_workqueue(
                                dev_name(drv_data->master->dev.parent));
        if (drv_data->workqueue == NULL)
                return -EBUSY;

        return 0;
}

static inline int bfin_spi_start_queue(struct master_data *drv_data)
{
        unsigned long flags;

        spin_lock_irqsave(&drv_data->lock, flags);

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

        drv_data->running = true;
        drv_data->cur_msg = NULL;
        drv_data->cur_transfer = NULL;
        drv_data->cur_chip = NULL;
        spin_unlock_irqrestore(&drv_data->lock, flags);

        queue_work(drv_data->workqueue, &drv_data->pump_messages);

        return 0;
}

static inline int bfin_spi_stop_queue(struct master_data *drv_data)
{
        unsigned long flags;
        unsigned limit = 500;
        int status = 0;

        spin_lock_irqsave(&drv_data->lock, flags);

        /*
         * This is a bit lame, but is optimized for the common execution path.
         * A wait_queue on the drv_data->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
         */
        drv_data->running = false;
        while (!list_empty(&drv_data->queue) && drv_data->busy && limit--) {
                spin_unlock_irqrestore(&drv_data->lock, flags);
                msleep(10);
                spin_lock_irqsave(&drv_data->lock, flags);
        }

        if (!list_empty(&drv_data->queue) || drv_data->busy)
                status = -EBUSY;

        spin_unlock_irqrestore(&drv_data->lock, flags);

        return status;
}

static inline int bfin_spi_destroy_queue(struct master_data *drv_data)
{
        int status;

        status = bfin_spi_stop_queue(drv_data);
        if (status != 0)
                return status;

        destroy_workqueue(drv_data->workqueue);

        return 0;
}

static int __init bfin_spi_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct bfin5xx_spi_master *platform_info;
        struct spi_master *master;
        struct master_data *drv_data;
        struct resource *res;
        int status = 0;

        platform_info = dev->platform_data;

        /* Allocate master with space for drv_data */
        master = spi_alloc_master(dev, sizeof(*drv_data));
        if (!master) {
                dev_err(&pdev->dev, "can not alloc spi_master\n");
                return -ENOMEM;
        }

        drv_data = spi_master_get_devdata(master);
        drv_data->master = master;
        drv_data->master_info = platform_info;
        drv_data->pdev = pdev;
        drv_data->pin_req = platform_info->pin_req;

        /* the spi->mode bits supported by this driver: */
        master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST;

        master->bus_num = pdev->id;
        master->num_chipselect = platform_info->num_chipselect;
        master->cleanup = bfin_spi_cleanup;
        master->setup = bfin_spi_setup;
        master->transfer = bfin_spi_transfer;

        /* Find and map our resources */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (res == NULL) {
                dev_err(dev, "Cannot get IORESOURCE_MEM\n");
                status = -ENOENT;
                goto out_error_get_res;
        }

        drv_data->regs_base = ioremap(res->start, resource_size(res));
        if (drv_data->regs_base == NULL) {
                dev_err(dev, "Cannot map IO\n");
                status = -ENXIO;
                goto out_error_ioremap;
        }

        res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
        if (res == NULL) {
                dev_err(dev, "No DMA channel specified\n");
                status = -ENOENT;
                goto out_error_free_io;
        }
        drv_data->dma_channel = res->start;

        drv_data->spi_irq = platform_get_irq(pdev, 0);
        if (drv_data->spi_irq < 0) {
                dev_err(dev, "No spi pio irq specified\n");
                status = -ENOENT;
                goto out_error_free_io;
        }

        /* Initial and start queue */
        status = bfin_spi_init_queue(drv_data);
        if (status != 0) {
                dev_err(dev, "problem initializing queue\n");
                goto out_error_queue_alloc;
        }

        status = bfin_spi_start_queue(drv_data);
        if (status != 0) {
                dev_err(dev, "problem starting queue\n");
                goto out_error_queue_alloc;
        }

        status = peripheral_request_list(drv_data->pin_req, DRV_NAME);
        if (status != 0) {
                dev_err(&pdev->dev, ": Requesting Peripherals failed\n");
                goto out_error_queue_alloc;
        }

        /* Reset SPI registers. If these registers were used by the boot loader,
         * the sky may fall on your head if you enable the dma controller.
         */
        write_CTRL(drv_data, BIT_CTL_CPHA | BIT_CTL_MASTER);
        write_FLAG(drv_data, 0xFF00);

        /* Register with the SPI framework */
        platform_set_drvdata(pdev, drv_data);
        status = spi_register_master(master);
        if (status != 0) {
                dev_err(dev, "problem registering spi master\n");
                goto out_error_queue_alloc;
        }

        dev_info(dev, "%s, Version %s, regs_base@%p, dma channel@%d\n",
                DRV_DESC, DRV_VERSION, drv_data->regs_base,
                drv_data->dma_channel);
        return status;

out_error_queue_alloc:
        bfin_spi_destroy_queue(drv_data);
out_error_free_io:
        iounmap((void *) drv_data->regs_base);
out_error_ioremap:
out_error_get_res:
        spi_master_put(master);

        return status;
}

/* stop hardware and remove the driver */
static int __devexit bfin_spi_remove(struct platform_device *pdev)
{
        struct master_data *drv_data = platform_get_drvdata(pdev);
        int status = 0;

        if (!drv_data)
                return 0;

        /* Remove the queue */
        status = bfin_spi_destroy_queue(drv_data);
        if (status != 0)
                return status;

        /* Disable the SSP at the peripheral and SOC level */
        bfin_spi_disable(drv_data);

        /* Release DMA */
        if (drv_data->master_info->enable_dma) {
                if (dma_channel_active(drv_data->dma_channel))
                        free_dma(drv_data->dma_channel);
        }

        if (drv_data->irq_requested) {
                free_irq(drv_data->spi_irq, drv_data);
                drv_data->irq_requested = 0;
        }

        /* Disconnect from the SPI framework */
        spi_unregister_master(drv_data->master);

        peripheral_free_list(drv_data->pin_req);

        /* Prevent double remove */
        platform_set_drvdata(pdev, NULL);

        return 0;
}

#ifdef CONFIG_PM
static int bfin_spi_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct master_data *drv_data = platform_get_drvdata(pdev);
        int status = 0;

        status = bfin_spi_stop_queue(drv_data);
        if (status != 0)
                return status;

        drv_data->ctrl_reg = read_CTRL(drv_data);
        drv_data->flag_reg = read_FLAG(drv_data);

        /*
         * reset SPI_CTL and SPI_FLG registers
         */
        write_CTRL(drv_data, BIT_CTL_CPHA | BIT_CTL_MASTER);
        write_FLAG(drv_data, 0xFF00);

        return 0;
}

static int bfin_spi_resume(struct platform_device *pdev)
{
        struct master_data *drv_data = platform_get_drvdata(pdev);
        int status = 0;

        write_CTRL(drv_data, drv_data->ctrl_reg);
        write_FLAG(drv_data, drv_data->flag_reg);

        /* Start the queue running */
        status = bfin_spi_start_queue(drv_data);
        if (status != 0) {
                dev_err(&pdev->dev, "problem starting queue (%d)\n", status);
                return status;
        }

        return 0;
}
#else
#define bfin_spi_suspend NULL
#define bfin_spi_resume NULL
#endif                          /* CONFIG_PM */

MODULE_ALIAS("platform:bfin-spi");
static struct platform_driver bfin_spi_driver = {
        .driver = {
                .name   = DRV_NAME,
                .owner  = THIS_MODULE,
        },
        .suspend        = bfin_spi_suspend,
        .resume         = bfin_spi_resume,
        .remove         = __devexit_p(bfin_spi_remove),
};

static int __init bfin_spi_init(void)
{
        return platform_driver_probe(&bfin_spi_driver, bfin_spi_probe);
}
module_init(bfin_spi_init);

static void __exit bfin_spi_exit(void)
{
        platform_driver_unregister(&bfin_spi_driver);
}
module_exit(bfin_spi_exit);