Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

[mirror_ubuntu-focal-kernel.git] / drivers / pci / msi.c

// SPDX-License-Identifier: GPL-2.0
/*
 * PCI Message Signaled Interrupt (MSI)
 *
 * Copyright (C) 2003-2004 Intel
 * Copyright (C) Tom Long Nguyen (tom.l.nguyen@intel.com)
 * Copyright (C) 2016 Christoph Hellwig.
 */

#include <linux/err.h>
#include <linux/mm.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/export.h>
#include <linux/ioport.h>
#include <linux/pci.h>
#include <linux/proc_fs.h>
#include <linux/msi.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/acpi_iort.h>
#include <linux/slab.h>
#include <linux/irqdomain.h>
#include <linux/of_irq.h>

#include "pci.h"

static int pci_msi_enable = 1;
int pci_msi_ignore_mask;

#define msix_table_size(flags)  ((flags & PCI_MSIX_FLAGS_QSIZE) + 1)

#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
static int pci_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
{
        struct irq_domain *domain;

        domain = dev_get_msi_domain(&dev->dev);
        if (domain && irq_domain_is_hierarchy(domain))
                return msi_domain_alloc_irqs(domain, &dev->dev, nvec);

        return arch_setup_msi_irqs(dev, nvec, type);
}

static void pci_msi_teardown_msi_irqs(struct pci_dev *dev)
{
        struct irq_domain *domain;

        domain = dev_get_msi_domain(&dev->dev);
        if (domain && irq_domain_is_hierarchy(domain))
                msi_domain_free_irqs(domain, &dev->dev);
        else
                arch_teardown_msi_irqs(dev);
}
#else
#define pci_msi_setup_msi_irqs          arch_setup_msi_irqs
#define pci_msi_teardown_msi_irqs       arch_teardown_msi_irqs
#endif

/* Arch hooks */

int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
{
        struct msi_controller *chip = dev->bus->msi;
        int err;

        if (!chip || !chip->setup_irq)
                return -EINVAL;

        err = chip->setup_irq(chip, dev, desc);
        if (err < 0)
                return err;

        irq_set_chip_data(desc->irq, chip);

        return 0;
}

void __weak arch_teardown_msi_irq(unsigned int irq)
{
        struct msi_controller *chip = irq_get_chip_data(irq);

        if (!chip || !chip->teardown_irq)
                return;

        chip->teardown_irq(chip, irq);
}

int __weak arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
{
        struct msi_controller *chip = dev->bus->msi;
        struct msi_desc *entry;
        int ret;

        if (chip && chip->setup_irqs)
                return chip->setup_irqs(chip, dev, nvec, type);
        /*
         * If an architecture wants to support multiple MSI, it needs to
         * override arch_setup_msi_irqs()
         */
        if (type == PCI_CAP_ID_MSI && nvec > 1)
                return 1;

        for_each_pci_msi_entry(entry, dev) {
                ret = arch_setup_msi_irq(dev, entry);
                if (ret < 0)
                        return ret;
                if (ret > 0)
                        return -ENOSPC;
        }

        return 0;
}

/*
 * We have a default implementation available as a separate non-weak
 * function, as it is used by the Xen x86 PCI code
 */
void default_teardown_msi_irqs(struct pci_dev *dev)
{
        int i;
        struct msi_desc *entry;

        for_each_pci_msi_entry(entry, dev)
                if (entry->irq)
                        for (i = 0; i < entry->nvec_used; i++)
                                arch_teardown_msi_irq(entry->irq + i);
}

void __weak arch_teardown_msi_irqs(struct pci_dev *dev)
{
        return default_teardown_msi_irqs(dev);
}

static void default_restore_msi_irq(struct pci_dev *dev, int irq)
{
        struct msi_desc *entry;

        entry = NULL;
        if (dev->msix_enabled) {
                for_each_pci_msi_entry(entry, dev) {
                        if (irq == entry->irq)
                                break;
                }
        } else if (dev->msi_enabled)  {
                entry = irq_get_msi_desc(irq);
        }

        if (entry)
                __pci_write_msi_msg(entry, &entry->msg);
}

void __weak arch_restore_msi_irqs(struct pci_dev *dev)
{
        return default_restore_msi_irqs(dev);
}

static inline __attribute_const__ u32 msi_mask(unsigned x)
{
        /* Don't shift by >= width of type */
        if (x >= 5)
                return 0xffffffff;
        return (1 << (1 << x)) - 1;
}

/*
 * PCI 2.3 does not specify mask bits for each MSI interrupt.  Attempting to
 * mask all MSI interrupts by clearing the MSI enable bit does not work
 * reliably as devices without an INTx disable bit will then generate a
 * level IRQ which will never be cleared.
 */
u32 __pci_msi_desc_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
{
        u32 mask_bits = desc->masked;

        if (pci_msi_ignore_mask || !desc->msi_attrib.maskbit)
                return 0;

        mask_bits &= ~mask;
        mask_bits |= flag;
        pci_write_config_dword(msi_desc_to_pci_dev(desc), desc->mask_pos,
                               mask_bits);

        return mask_bits;
}

static void msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
{
        desc->masked = __pci_msi_desc_mask_irq(desc, mask, flag);
}

static void __iomem *pci_msix_desc_addr(struct msi_desc *desc)
{
        if (desc->msi_attrib.is_virtual)
                return NULL;

        return desc->mask_base +
                desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;
}

/*
 * This internal function does not flush PCI writes to the device.
 * All users must ensure that they read from the device before either
 * assuming that the device state is up to date, or returning out of this
 * file.  This saves a few milliseconds when initialising devices with lots
 * of MSI-X interrupts.
 */
u32 __pci_msix_desc_mask_irq(struct msi_desc *desc, u32 flag)
{
        u32 mask_bits = desc->masked;
        void __iomem *desc_addr;

        if (pci_msi_ignore_mask)
                return 0;
        desc_addr = pci_msix_desc_addr(desc);
        if (!desc_addr)
                return 0;

        mask_bits &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
        if (flag)
                mask_bits |= PCI_MSIX_ENTRY_CTRL_MASKBIT;

        writel(mask_bits, desc_addr + PCI_MSIX_ENTRY_VECTOR_CTRL);

        return mask_bits;
}

static void msix_mask_irq(struct msi_desc *desc, u32 flag)
{
        desc->masked = __pci_msix_desc_mask_irq(desc, flag);
}

static void msi_set_mask_bit(struct irq_data *data, u32 flag)
{
        struct msi_desc *desc = irq_data_get_msi_desc(data);

        if (desc->msi_attrib.is_msix) {
                msix_mask_irq(desc, flag);
                readl(desc->mask_base);         /* Flush write to device */
        } else {
                unsigned offset = data->irq - desc->irq;
                msi_mask_irq(desc, 1 << offset, flag << offset);
        }
}

/**
 * pci_msi_mask_irq - Generic IRQ chip callback to mask PCI/MSI interrupts
 * @data:       pointer to irqdata associated to that interrupt
 */
void pci_msi_mask_irq(struct irq_data *data)
{
        msi_set_mask_bit(data, 1);
}
EXPORT_SYMBOL_GPL(pci_msi_mask_irq);

/**
 * pci_msi_unmask_irq - Generic IRQ chip callback to unmask PCI/MSI interrupts
 * @data:       pointer to irqdata associated to that interrupt
 */
void pci_msi_unmask_irq(struct irq_data *data)
{
        msi_set_mask_bit(data, 0);
}
EXPORT_SYMBOL_GPL(pci_msi_unmask_irq);

void default_restore_msi_irqs(struct pci_dev *dev)
{
        struct msi_desc *entry;

        for_each_pci_msi_entry(entry, dev)
                default_restore_msi_irq(dev, entry->irq);
}

void __pci_read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
        struct pci_dev *dev = msi_desc_to_pci_dev(entry);

        BUG_ON(dev->current_state != PCI_D0);

        if (entry->msi_attrib.is_msix) {
                void __iomem *base = pci_msix_desc_addr(entry);

                if (!base) {
                        WARN_ON(1);
                        return;
                }

                msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR);
                msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR);
                msg->data = readl(base + PCI_MSIX_ENTRY_DATA);
        } else {
                int pos = dev->msi_cap;
                u16 data;

                pci_read_config_dword(dev, pos + PCI_MSI_ADDRESS_LO,
                                      &msg->address_lo);
                if (entry->msi_attrib.is_64) {
                        pci_read_config_dword(dev, pos + PCI_MSI_ADDRESS_HI,
                                              &msg->address_hi);
                        pci_read_config_word(dev, pos + PCI_MSI_DATA_64, &data);
                } else {
                        msg->address_hi = 0;
                        pci_read_config_word(dev, pos + PCI_MSI_DATA_32, &data);
                }
                msg->data = data;
        }
}

void __pci_write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
        struct pci_dev *dev = msi_desc_to_pci_dev(entry);

        if (dev->current_state != PCI_D0 || pci_dev_is_disconnected(dev)) {
                /* Don't touch the hardware now */
        } else if (entry->msi_attrib.is_msix) {
                void __iomem *base = pci_msix_desc_addr(entry);

                if (!base)
                        goto skip;

                writel(msg->address_lo, base + PCI_MSIX_ENTRY_LOWER_ADDR);
                writel(msg->address_hi, base + PCI_MSIX_ENTRY_UPPER_ADDR);
                writel(msg->data, base + PCI_MSIX_ENTRY_DATA);
        } else {
                int pos = dev->msi_cap;
                u16 msgctl;

                pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl);
                msgctl &= ~PCI_MSI_FLAGS_QSIZE;
                msgctl |= entry->msi_attrib.multiple << 4;
                pci_write_config_word(dev, pos + PCI_MSI_FLAGS, msgctl);

                pci_write_config_dword(dev, pos + PCI_MSI_ADDRESS_LO,
                                       msg->address_lo);
                if (entry->msi_attrib.is_64) {
                        pci_write_config_dword(dev, pos + PCI_MSI_ADDRESS_HI,
                                               msg->address_hi);
                        pci_write_config_word(dev, pos + PCI_MSI_DATA_64,
                                              msg->data);
                } else {
                        pci_write_config_word(dev, pos + PCI_MSI_DATA_32,
                                              msg->data);
                }
        }

skip:
        entry->msg = *msg;

        if (entry->write_msi_msg)
                entry->write_msi_msg(entry, entry->write_msi_msg_data);

}

void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg)
{
        struct msi_desc *entry = irq_get_msi_desc(irq);

        __pci_write_msi_msg(entry, msg);
}
EXPORT_SYMBOL_GPL(pci_write_msi_msg);

static void free_msi_irqs(struct pci_dev *dev)
{
        struct list_head *msi_list = dev_to_msi_list(&dev->dev);
        struct msi_desc *entry, *tmp;
        struct attribute **msi_attrs;
        struct device_attribute *dev_attr;
        int i, count = 0;

        for_each_pci_msi_entry(entry, dev)
                if (entry->irq)
                        for (i = 0; i < entry->nvec_used; i++)
                                BUG_ON(irq_has_action(entry->irq + i));

        pci_msi_teardown_msi_irqs(dev);

        list_for_each_entry_safe(entry, tmp, msi_list, list) {
                if (entry->msi_attrib.is_msix) {
                        if (list_is_last(&entry->list, msi_list))
                                iounmap(entry->mask_base);
                }

                list_del(&entry->list);
                free_msi_entry(entry);
        }

        if (dev->msi_irq_groups) {
                sysfs_remove_groups(&dev->dev.kobj, dev->msi_irq_groups);
                msi_attrs = dev->msi_irq_groups[0]->attrs;
                while (msi_attrs[count]) {
                        dev_attr = container_of(msi_attrs[count],
                                                struct device_attribute, attr);
                        kfree(dev_attr->attr.name);
                        kfree(dev_attr);
                        ++count;
                }
                kfree(msi_attrs);
                kfree(dev->msi_irq_groups[0]);
                kfree(dev->msi_irq_groups);
                dev->msi_irq_groups = NULL;
        }
}

static void pci_intx_for_msi(struct pci_dev *dev, int enable)
{
        if (!(dev->dev_flags & PCI_DEV_FLAGS_MSI_INTX_DISABLE_BUG))
                pci_intx(dev, enable);
}

static void __pci_restore_msi_state(struct pci_dev *dev)
{
        u16 control;
        struct msi_desc *entry;

        if (!dev->msi_enabled)
                return;

        entry = irq_get_msi_desc(dev->irq);

        pci_intx_for_msi(dev, 0);
        pci_msi_set_enable(dev, 0);
        arch_restore_msi_irqs(dev);

        pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
        msi_mask_irq(entry, msi_mask(entry->msi_attrib.multi_cap),
                     entry->masked);
        control &= ~PCI_MSI_FLAGS_QSIZE;
        control |= (entry->msi_attrib.multiple << 4) | PCI_MSI_FLAGS_ENABLE;
        pci_write_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, control);
}

static void __pci_restore_msix_state(struct pci_dev *dev)
{
        struct msi_desc *entry;

        if (!dev->msix_enabled)
                return;
        BUG_ON(list_empty(dev_to_msi_list(&dev->dev)));

        /* route the table */
        pci_intx_for_msi(dev, 0);
        pci_msix_clear_and_set_ctrl(dev, 0,
                                PCI_MSIX_FLAGS_ENABLE | PCI_MSIX_FLAGS_MASKALL);

        arch_restore_msi_irqs(dev);
        for_each_pci_msi_entry(entry, dev)
                msix_mask_irq(entry, entry->masked);

        pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
}

void pci_restore_msi_state(struct pci_dev *dev)
{
        __pci_restore_msi_state(dev);
        __pci_restore_msix_state(dev);
}
EXPORT_SYMBOL_GPL(pci_restore_msi_state);

static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct msi_desc *entry;
        unsigned long irq;
        int retval;

        retval = kstrtoul(attr->attr.name, 10, &irq);
        if (retval)
                return retval;

        entry = irq_get_msi_desc(irq);
        if (entry)
                return sprintf(buf, "%s\n",
                                entry->msi_attrib.is_msix ? "msix" : "msi");

        return -ENODEV;
}

static int populate_msi_sysfs(struct pci_dev *pdev)
{
        struct attribute **msi_attrs;
        struct attribute *msi_attr;
        struct device_attribute *msi_dev_attr;
        struct attribute_group *msi_irq_group;
        const struct attribute_group **msi_irq_groups;
        struct msi_desc *entry;
        int ret = -ENOMEM;
        int num_msi = 0;
        int count = 0;
        int i;

        /* Determine how many msi entries we have */
        for_each_pci_msi_entry(entry, pdev)
                num_msi += entry->nvec_used;
        if (!num_msi)
                return 0;

        /* Dynamically create the MSI attributes for the PCI device */
        msi_attrs = kcalloc(num_msi + 1, sizeof(void *), GFP_KERNEL);
        if (!msi_attrs)
                return -ENOMEM;
        for_each_pci_msi_entry(entry, pdev) {
                for (i = 0; i < entry->nvec_used; i++) {
                        msi_dev_attr = kzalloc(sizeof(*msi_dev_attr), GFP_KERNEL);
                        if (!msi_dev_attr)
                                goto error_attrs;
                        msi_attrs[count] = &msi_dev_attr->attr;

                        sysfs_attr_init(&msi_dev_attr->attr);
                        msi_dev_attr->attr.name = kasprintf(GFP_KERNEL, "%d",
                                                            entry->irq + i);
                        if (!msi_dev_attr->attr.name)
                                goto error_attrs;
                        msi_dev_attr->attr.mode = S_IRUGO;
                        msi_dev_attr->show = msi_mode_show;
                        ++count;
                }
        }

        msi_irq_group = kzalloc(sizeof(*msi_irq_group), GFP_KERNEL);
        if (!msi_irq_group)
                goto error_attrs;
        msi_irq_group->name = "msi_irqs";
        msi_irq_group->attrs = msi_attrs;

        msi_irq_groups = kcalloc(2, sizeof(void *), GFP_KERNEL);
        if (!msi_irq_groups)
                goto error_irq_group;
        msi_irq_groups[0] = msi_irq_group;

        ret = sysfs_create_groups(&pdev->dev.kobj, msi_irq_groups);
        if (ret)
                goto error_irq_groups;
        pdev->msi_irq_groups = msi_irq_groups;

        return 0;

error_irq_groups:
        kfree(msi_irq_groups);
error_irq_group:
        kfree(msi_irq_group);
error_attrs:
        count = 0;
        msi_attr = msi_attrs[count];
        while (msi_attr) {
                msi_dev_attr = container_of(msi_attr, struct device_attribute, attr);
                kfree(msi_attr->name);
                kfree(msi_dev_attr);
                ++count;
                msi_attr = msi_attrs[count];
        }
        kfree(msi_attrs);
        return ret;
}

static struct msi_desc *
msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
{
        struct irq_affinity_desc *masks = NULL;
        struct msi_desc *entry;
        u16 control;

        if (affd)
                masks = irq_create_affinity_masks(nvec, affd);

        /* MSI Entry Initialization */
        entry = alloc_msi_entry(&dev->dev, nvec, masks);
        if (!entry)
                goto out;

        pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);

        entry->msi_attrib.is_msix       = 0;
        entry->msi_attrib.is_64         = !!(control & PCI_MSI_FLAGS_64BIT);
        entry->msi_attrib.is_virtual    = 0;
        entry->msi_attrib.entry_nr      = 0;
        entry->msi_attrib.maskbit       = !!(control & PCI_MSI_FLAGS_MASKBIT);
        entry->msi_attrib.default_irq   = dev->irq;     /* Save IOAPIC IRQ */
        entry->msi_attrib.multi_cap     = (control & PCI_MSI_FLAGS_QMASK) >> 1;
        entry->msi_attrib.multiple      = ilog2(__roundup_pow_of_two(nvec));

        if (control & PCI_MSI_FLAGS_64BIT)
                entry->mask_pos = dev->msi_cap + PCI_MSI_MASK_64;
        else
                entry->mask_pos = dev->msi_cap + PCI_MSI_MASK_32;

        /* Save the initial mask status */
        if (entry->msi_attrib.maskbit)
                pci_read_config_dword(dev, entry->mask_pos, &entry->masked);

out:
        kfree(masks);
        return entry;
}

static int msi_verify_entries(struct pci_dev *dev)
{
        struct msi_desc *entry;

        for_each_pci_msi_entry(entry, dev) {
                if (!dev->no_64bit_msi || !entry->msg.address_hi)
                        continue;
                pci_err(dev, "Device has broken 64-bit MSI but arch"
                        " tried to assign one above 4G\n");
                return -EIO;
        }
        return 0;
}

/**
 * msi_capability_init - configure device's MSI capability structure
 * @dev: pointer to the pci_dev data structure of MSI device function
 * @nvec: number of interrupts to allocate
 * @affd: description of automatic IRQ affinity assignments (may be %NULL)
 *
 * Setup the MSI capability structure of the device with the requested
 * number of interrupts.  A return value of zero indicates the successful
 * setup of an entry with the new MSI IRQ.  A negative return value indicates
 * an error, and a positive return value indicates the number of interrupts
 * which could have been allocated.
 */
static int msi_capability_init(struct pci_dev *dev, int nvec,
                               struct irq_affinity *affd)
{
        struct msi_desc *entry;
        int ret;
        unsigned mask;

        pci_msi_set_enable(dev, 0);     /* Disable MSI during set up */

        entry = msi_setup_entry(dev, nvec, affd);
        if (!entry)
                return -ENOMEM;

        /* All MSIs are unmasked by default; mask them all */
        mask = msi_mask(entry->msi_attrib.multi_cap);
        msi_mask_irq(entry, mask, mask);

        list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));

        /* Configure MSI capability structure */
        ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
        if (ret) {
                msi_mask_irq(entry, mask, ~mask);
                free_msi_irqs(dev);
                return ret;
        }

        ret = msi_verify_entries(dev);
        if (ret) {
                msi_mask_irq(entry, mask, ~mask);
                free_msi_irqs(dev);
                return ret;
        }

        ret = populate_msi_sysfs(dev);
        if (ret) {
                msi_mask_irq(entry, mask, ~mask);
                free_msi_irqs(dev);
                return ret;
        }

        /* Set MSI enabled bits */
        pci_intx_for_msi(dev, 0);
        pci_msi_set_enable(dev, 1);
        dev->msi_enabled = 1;

        pcibios_free_irq(dev);
        dev->irq = entry->irq;
        return 0;
}

static void __iomem *msix_map_region(struct pci_dev *dev, unsigned nr_entries)
{
        resource_size_t phys_addr;
        u32 table_offset;
        unsigned long flags;
        u8 bir;

        pci_read_config_dword(dev, dev->msix_cap + PCI_MSIX_TABLE,
                              &table_offset);
        bir = (u8)(table_offset & PCI_MSIX_TABLE_BIR);
        flags = pci_resource_flags(dev, bir);
        if (!flags || (flags & IORESOURCE_UNSET))
                return NULL;

        table_offset &= PCI_MSIX_TABLE_OFFSET;
        phys_addr = pci_resource_start(dev, bir) + table_offset;

        return ioremap_nocache(phys_addr, nr_entries * PCI_MSIX_ENTRY_SIZE);
}

static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
                              struct msix_entry *entries, int nvec,
                              struct irq_affinity *affd)
{
        struct irq_affinity_desc *curmsk, *masks = NULL;
        struct msi_desc *entry;
        int ret, i;
        int vec_count = pci_msix_vec_count(dev);

        if (affd)
                masks = irq_create_affinity_masks(nvec, affd);

        for (i = 0, curmsk = masks; i < nvec; i++) {
                entry = alloc_msi_entry(&dev->dev, 1, curmsk);
                if (!entry) {
                        if (!i)
                                iounmap(base);
                        else
                                free_msi_irqs(dev);
                        /* No enough memory. Don't try again */
                        ret = -ENOMEM;
                        goto out;
                }

                entry->msi_attrib.is_msix       = 1;
                entry->msi_attrib.is_64         = 1;
                if (entries)
                        entry->msi_attrib.entry_nr = entries[i].entry;
                else
                        entry->msi_attrib.entry_nr = i;

                entry->msi_attrib.is_virtual =
                        entry->msi_attrib.entry_nr >= vec_count;

                entry->msi_attrib.default_irq   = dev->irq;
                entry->mask_base                = base;

                list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));
                if (masks)
                        curmsk++;
        }
        ret = 0;
out:
        kfree(masks);
        return ret;
}

static void msix_program_entries(struct pci_dev *dev,
                                 struct msix_entry *entries)
{
        struct msi_desc *entry;
        int i = 0;
        void __iomem *desc_addr;

        for_each_pci_msi_entry(entry, dev) {
                if (entries)
                        entries[i++].vector = entry->irq;

                desc_addr = pci_msix_desc_addr(entry);
                if (desc_addr)
                        entry->masked = readl(desc_addr +
                                              PCI_MSIX_ENTRY_VECTOR_CTRL);
                else
                        entry->masked = 0;

                msix_mask_irq(entry, 1);
        }
}

/**
 * msix_capability_init - configure device's MSI-X capability
 * @dev: pointer to the pci_dev data structure of MSI-X device function
 * @entries: pointer to an array of struct msix_entry entries
 * @nvec: number of @entries
 * @affd: Optional pointer to enable automatic affinity assignment
 *
 * Setup the MSI-X capability structure of device function with a
 * single MSI-X IRQ. A return of zero indicates the successful setup of
 * requested MSI-X entries with allocated IRQs or non-zero for otherwise.
 **/
static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
                                int nvec, struct irq_affinity *affd)
{
        int ret;
        u16 control;
        void __iomem *base;

        /* Ensure MSI-X is disabled while it is set up */
        pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);

        pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
        /* Request & Map MSI-X table region */
        base = msix_map_region(dev, msix_table_size(control));
        if (!base)
                return -ENOMEM;

        ret = msix_setup_entries(dev, base, entries, nvec, affd);
        if (ret)
                return ret;

        ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
        if (ret)
                goto out_avail;

        /* Check if all MSI entries honor device restrictions */
        ret = msi_verify_entries(dev);
        if (ret)
                goto out_free;

        /*
         * Some devices require MSI-X to be enabled before we can touch the
         * MSI-X registers.  We need to mask all the vectors to prevent
         * interrupts coming in before they're fully set up.
         */
        pci_msix_clear_and_set_ctrl(dev, 0,
                                PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE);

        msix_program_entries(dev, entries);

        ret = populate_msi_sysfs(dev);
        if (ret)
                goto out_free;

        /* Set MSI-X enabled bits and unmask the function */
        pci_intx_for_msi(dev, 0);
        dev->msix_enabled = 1;
        pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);

        pcibios_free_irq(dev);
        return 0;

out_avail:
        if (ret < 0) {
                /*
                 * If we had some success, report the number of IRQs
                 * we succeeded in setting up.
                 */
                struct msi_desc *entry;
                int avail = 0;

                for_each_pci_msi_entry(entry, dev) {
                        if (entry->irq != 0)
                                avail++;
                }
                if (avail != 0)
                        ret = avail;
        }

out_free:
        free_msi_irqs(dev);

        return ret;
}

/**
 * pci_msi_supported - check whether MSI may be enabled on a device
 * @dev: pointer to the pci_dev data structure of MSI device function
 * @nvec: how many MSIs have been requested?
 *
 * Look at global flags, the device itself, and its parent buses
 * to determine if MSI/-X are supported for the device. If MSI/-X is
 * supported return 1, else return 0.
 **/
static int pci_msi_supported(struct pci_dev *dev, int nvec)
{
        struct pci_bus *bus;

        /* MSI must be globally enabled and supported by the device */
        if (!pci_msi_enable)
                return 0;

        if (!dev || dev->no_msi || dev->current_state != PCI_D0)
                return 0;

        /*
         * You can't ask to have 0 or less MSIs configured.
         *  a) it's stupid ..
         *  b) the list manipulation code assumes nvec >= 1.
         */
        if (nvec < 1)
                return 0;

        /*
         * Any bridge which does NOT route MSI transactions from its
         * secondary bus to its primary bus must set NO_MSI flag on
         * the secondary pci_bus.
         * We expect only arch-specific PCI host bus controller driver
         * or quirks for specific PCI bridges to be setting NO_MSI.
         */
        for (bus = dev->bus; bus; bus = bus->parent)
                if (bus->bus_flags & PCI_BUS_FLAGS_NO_MSI)
                        return 0;

        return 1;
}

/**
 * pci_msi_vec_count - Return the number of MSI vectors a device can send
 * @dev: device to report about
 *
 * This function returns the number of MSI vectors a device requested via
 * Multiple Message Capable register. It returns a negative errno if the
 * device is not capable sending MSI interrupts. Otherwise, the call succeeds
 * and returns a power of two, up to a maximum of 2^5 (32), according to the
 * MSI specification.
 **/
int pci_msi_vec_count(struct pci_dev *dev)
{
        int ret;
        u16 msgctl;

        if (!dev->msi_cap)
                return -EINVAL;

        pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl);
        ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);

        return ret;
}
EXPORT_SYMBOL(pci_msi_vec_count);

static void pci_msi_shutdown(struct pci_dev *dev)
{
        struct msi_desc *desc;
        u32 mask;

        if (!pci_msi_enable || !dev || !dev->msi_enabled)
                return;

        BUG_ON(list_empty(dev_to_msi_list(&dev->dev)));
        desc = first_pci_msi_entry(dev);

        pci_msi_set_enable(dev, 0);
        pci_intx_for_msi(dev, 1);
        dev->msi_enabled = 0;

        /* Return the device with MSI unmasked as initial states */
        mask = msi_mask(desc->msi_attrib.multi_cap);
        /* Keep cached state to be restored */
        __pci_msi_desc_mask_irq(desc, mask, ~mask);

        /* Restore dev->irq to its default pin-assertion IRQ */
        dev->irq = desc->msi_attrib.default_irq;
        pcibios_alloc_irq(dev);
}

void pci_disable_msi(struct pci_dev *dev)
{
        if (!pci_msi_enable || !dev || !dev->msi_enabled)
                return;

        pci_msi_shutdown(dev);
        free_msi_irqs(dev);
}
EXPORT_SYMBOL(pci_disable_msi);

/**
 * pci_msix_vec_count - return the number of device's MSI-X table entries
 * @dev: pointer to the pci_dev data structure of MSI-X device function
 * This function returns the number of device's MSI-X table entries and
 * therefore the number of MSI-X vectors device is capable of sending.
 * It returns a negative errno if the device is not capable of sending MSI-X
 * interrupts.
 **/
int pci_msix_vec_count(struct pci_dev *dev)
{
        u16 control;

        if (!dev->msix_cap)
                return -EINVAL;

        pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
        return msix_table_size(control);
}
EXPORT_SYMBOL(pci_msix_vec_count);

static int __pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries,
                             int nvec, struct irq_affinity *affd, int flags)
{
        int nr_entries;
        int i, j;

        if (!pci_msi_supported(dev, nvec))
                return -EINVAL;

        nr_entries = pci_msix_vec_count(dev);
        if (nr_entries < 0)
                return nr_entries;
        if (nvec > nr_entries && !(flags & PCI_IRQ_VIRTUAL))
                return nr_entries;

        if (entries) {
                /* Check for any invalid entries */
                for (i = 0; i < nvec; i++) {
                        if (entries[i].entry >= nr_entries)
                                return -EINVAL;         /* invalid entry */
                        for (j = i + 1; j < nvec; j++) {
                                if (entries[i].entry == entries[j].entry)
                                        return -EINVAL; /* duplicate entry */
                        }
                }
        }

        /* Check whether driver already requested for MSI IRQ */
        if (dev->msi_enabled) {
                pci_info(dev, "can't enable MSI-X (MSI IRQ already assigned)\n");
                return -EINVAL;
        }
        return msix_capability_init(dev, entries, nvec, affd);
}

static void pci_msix_shutdown(struct pci_dev *dev)
{
        struct msi_desc *entry;

        if (!pci_msi_enable || !dev || !dev->msix_enabled)
                return;

        if (pci_dev_is_disconnected(dev)) {
                dev->msix_enabled = 0;
                return;
        }

        /* Return the device with MSI-X masked as initial states */
        for_each_pci_msi_entry(entry, dev) {
                /* Keep cached states to be restored */
                __pci_msix_desc_mask_irq(entry, 1);
        }

        pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
        pci_intx_for_msi(dev, 1);
        dev->msix_enabled = 0;
        pcibios_alloc_irq(dev);
}

void pci_disable_msix(struct pci_dev *dev)
{
        if (!pci_msi_enable || !dev || !dev->msix_enabled)
                return;

        pci_msix_shutdown(dev);
        free_msi_irqs(dev);
}
EXPORT_SYMBOL(pci_disable_msix);

void pci_no_msi(void)
{
        pci_msi_enable = 0;
}

/**
 * pci_msi_enabled - is MSI enabled?
 *
 * Returns true if MSI has not been disabled by the command-line option
 * pci=nomsi.
 **/
int pci_msi_enabled(void)
{
        return pci_msi_enable;
}
EXPORT_SYMBOL(pci_msi_enabled);

static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
                                  struct irq_affinity *affd)
{
        int nvec;
        int rc;

        if (!pci_msi_supported(dev, minvec))
                return -EINVAL;

        /* Check whether driver already requested MSI-X IRQs */
        if (dev->msix_enabled) {
                pci_info(dev, "can't enable MSI (MSI-X already enabled)\n");
                return -EINVAL;
        }

        if (maxvec < minvec)
                return -ERANGE;

        if (WARN_ON_ONCE(dev->msi_enabled))
                return -EINVAL;

        nvec = pci_msi_vec_count(dev);
        if (nvec < 0)
                return nvec;
        if (nvec < minvec)
                return -ENOSPC;

        if (nvec > maxvec)
                nvec = maxvec;

        for (;;) {
                if (affd) {
                        nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
                        if (nvec < minvec)
                                return -ENOSPC;
                }

                rc = msi_capability_init(dev, nvec, affd);
                if (rc == 0)
                        return nvec;

                if (rc < 0)
                        return rc;
                if (rc < minvec)
                        return -ENOSPC;

                nvec = rc;
        }
}

/* deprecated, don't use */
int pci_enable_msi(struct pci_dev *dev)
{
        int rc = __pci_enable_msi_range(dev, 1, 1, NULL);
        if (rc < 0)
                return rc;
        return 0;
}
EXPORT_SYMBOL(pci_enable_msi);

static int __pci_enable_msix_range(struct pci_dev *dev,
                                   struct msix_entry *entries, int minvec,
                                   int maxvec, struct irq_affinity *affd,
                                   int flags)
{
        int rc, nvec = maxvec;

        if (maxvec < minvec)
                return -ERANGE;

        if (WARN_ON_ONCE(dev->msix_enabled))
                return -EINVAL;

        for (;;) {
                if (affd) {
                        nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
                        if (nvec < minvec)
                                return -ENOSPC;
                }

                rc = __pci_enable_msix(dev, entries, nvec, affd, flags);
                if (rc == 0)
                        return nvec;

                if (rc < 0)
                        return rc;
                if (rc < minvec)
                        return -ENOSPC;

                nvec = rc;
        }
}

/**
 * pci_enable_msix_range - configure device's MSI-X capability structure
 * @dev: pointer to the pci_dev data structure of MSI-X device function
 * @entries: pointer to an array of MSI-X entries
 * @minvec: minimum number of MSI-X IRQs requested
 * @maxvec: maximum number of MSI-X IRQs requested
 *
 * Setup the MSI-X capability structure of device function with a maximum
 * possible number of interrupts in the range between @minvec and @maxvec
 * upon its software driver call to request for MSI-X mode enabled on its
 * hardware device function. It returns a negative errno if an error occurs.
 * If it succeeds, it returns the actual number of interrupts allocated and
 * indicates the successful configuration of MSI-X capability structure
 * with new allocated MSI-X interrupts.
 **/
int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
                int minvec, int maxvec)
{
        return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
}
EXPORT_SYMBOL(pci_enable_msix_range);

/**
 * pci_alloc_irq_vectors_affinity - allocate multiple IRQs for a device
 * @dev:                PCI device to operate on
 * @min_vecs:           minimum number of vectors required (must be >= 1)
 * @max_vecs:           maximum (desired) number of vectors
 * @flags:              flags or quirks for the allocation
 * @affd:               optional description of the affinity requirements
 *
 * Allocate up to @max_vecs interrupt vectors for @dev, using MSI-X or MSI
 * vectors if available, and fall back to a single legacy vector
 * if neither is available.  Return the number of vectors allocated,
 * (which might be smaller than @max_vecs) if successful, or a negative
 * error code on error. If less than @min_vecs interrupt vectors are
 * available for @dev the function will fail with -ENOSPC.
 *
 * To get the Linux IRQ number used for a vector that can be passed to
 * request_irq() use the pci_irq_vector() helper.
 */
int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
                                   unsigned int max_vecs, unsigned int flags,
                                   struct irq_affinity *affd)
{
        struct irq_affinity msi_default_affd = {0};
        int msix_vecs = -ENOSPC;
        int msi_vecs = -ENOSPC;

        if (flags & PCI_IRQ_AFFINITY) {
                if (!affd)
                        affd = &msi_default_affd;
        } else {
                if (WARN_ON(affd))
                        affd = NULL;
        }

        if (flags & PCI_IRQ_MSIX) {
                msix_vecs = __pci_enable_msix_range(dev, NULL, min_vecs,
                                                    max_vecs, affd, flags);
                if (msix_vecs > 0)
                        return msix_vecs;
        }

        if (flags & PCI_IRQ_MSI) {
                msi_vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs,
                                                  affd);
                if (msi_vecs > 0)
                        return msi_vecs;
        }

        /* use legacy IRQ if allowed */
        if (flags & PCI_IRQ_LEGACY) {
                if (min_vecs == 1 && dev->irq) {
                        /*
                         * Invoke the affinity spreading logic to ensure that
                         * the device driver can adjust queue configuration
                         * for the single interrupt case.
                         */
                        if (affd)
                                irq_create_affinity_masks(1, affd);
                        pci_intx(dev, 1);
                        return 1;
                }
        }

        if (msix_vecs == -ENOSPC)
                return -ENOSPC;
        return msi_vecs;
}
EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity);

/**
 * pci_free_irq_vectors - free previously allocated IRQs for a device
 * @dev:                PCI device to operate on
 *
 * Undoes the allocations and enabling in pci_alloc_irq_vectors().
 */
void pci_free_irq_vectors(struct pci_dev *dev)
{
        pci_disable_msix(dev);
        pci_disable_msi(dev);
}
EXPORT_SYMBOL(pci_free_irq_vectors);

/**
 * pci_irq_vector - return Linux IRQ number of a device vector
 * @dev: PCI device to operate on
 * @nr: device-relative interrupt vector index (0-based).
 */
int pci_irq_vector(struct pci_dev *dev, unsigned int nr)
{
        if (dev->msix_enabled) {
                struct msi_desc *entry;
                int i = 0;

                for_each_pci_msi_entry(entry, dev) {
                        if (i == nr)
                                return entry->irq;
                        i++;
                }
                WARN_ON_ONCE(1);
                return -EINVAL;
        }

        if (dev->msi_enabled) {
                struct msi_desc *entry = first_pci_msi_entry(dev);

                if (WARN_ON_ONCE(nr >= entry->nvec_used))
                        return -EINVAL;
        } else {
                if (WARN_ON_ONCE(nr > 0))
                        return -EINVAL;
        }

        return dev->irq + nr;
}
EXPORT_SYMBOL(pci_irq_vector);

/**
 * pci_irq_get_affinity - return the affinity of a particular MSI vector
 * @dev:        PCI device to operate on
 * @nr:         device-relative interrupt vector index (0-based).
 */
const struct cpumask *pci_irq_get_affinity(struct pci_dev *dev, int nr)
{
        if (dev->msix_enabled) {
                struct msi_desc *entry;
                int i = 0;

                for_each_pci_msi_entry(entry, dev) {
                        if (i == nr)
                                return &entry->affinity->mask;
                        i++;
                }
                WARN_ON_ONCE(1);
                return NULL;
        } else if (dev->msi_enabled) {
                struct msi_desc *entry = first_pci_msi_entry(dev);

                if (WARN_ON_ONCE(!entry || !entry->affinity ||
                                 nr >= entry->nvec_used))
                        return NULL;

                return &entry->affinity[nr].mask;
        } else {
                return cpu_possible_mask;
        }
}
EXPORT_SYMBOL(pci_irq_get_affinity);

/**
 * pci_irq_get_node - return the NUMA node of a particular MSI vector
 * @pdev:       PCI device to operate on
 * @vec:        device-relative interrupt vector index (0-based).
 */
int pci_irq_get_node(struct pci_dev *pdev, int vec)
{
        const struct cpumask *mask;

        mask = pci_irq_get_affinity(pdev, vec);
        if (mask)
                return local_memory_node(cpu_to_node(cpumask_first(mask)));
        return dev_to_node(&pdev->dev);
}
EXPORT_SYMBOL(pci_irq_get_node);

struct pci_dev *msi_desc_to_pci_dev(struct msi_desc *desc)
{
        return to_pci_dev(desc->dev);
}
EXPORT_SYMBOL(msi_desc_to_pci_dev);

void *msi_desc_to_pci_sysdata(struct msi_desc *desc)
{
        struct pci_dev *dev = msi_desc_to_pci_dev(desc);

        return dev->bus->sysdata;
}
EXPORT_SYMBOL_GPL(msi_desc_to_pci_sysdata);

#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
/**
 * pci_msi_domain_write_msg - Helper to write MSI message to PCI config space
 * @irq_data:   Pointer to interrupt data of the MSI interrupt
 * @msg:        Pointer to the message
 */
void pci_msi_domain_write_msg(struct irq_data *irq_data, struct msi_msg *msg)
{
        struct msi_desc *desc = irq_data_get_msi_desc(irq_data);

        /*
         * For MSI-X desc->irq is always equal to irq_data->irq. For
         * MSI only the first interrupt of MULTI MSI passes the test.
         */
        if (desc->irq == irq_data->irq)
                __pci_write_msi_msg(desc, msg);
}

/**
 * pci_msi_domain_calc_hwirq - Generate a unique ID for an MSI source
 * @dev:        Pointer to the PCI device
 * @desc:       Pointer to the MSI descriptor
 *
 * The ID number is only used within the irqdomain.
 */
irq_hw_number_t pci_msi_domain_calc_hwirq(struct pci_dev *dev,
                                          struct msi_desc *desc)
{
        return (irq_hw_number_t)desc->msi_attrib.entry_nr |
                pci_dev_id(dev) << 11 |
                (pci_domain_nr(dev->bus) & 0xFFFFFFFF) << 27;
}

static inline bool pci_msi_desc_is_multi_msi(struct msi_desc *desc)
{
        return !desc->msi_attrib.is_msix && desc->nvec_used > 1;
}

/**
 * pci_msi_domain_check_cap - Verify that @domain supports the capabilities
 *                            for @dev
 * @domain:     The interrupt domain to check
 * @info:       The domain info for verification
 * @dev:        The device to check
 *
 * Returns:
 *  0 if the functionality is supported
 *  1 if Multi MSI is requested, but the domain does not support it
 *  -ENOTSUPP otherwise
 */
int pci_msi_domain_check_cap(struct irq_domain *domain,
                             struct msi_domain_info *info, struct device *dev)
{
        struct msi_desc *desc = first_pci_msi_entry(to_pci_dev(dev));

        /* Special handling to support __pci_enable_msi_range() */
        if (pci_msi_desc_is_multi_msi(desc) &&
            !(info->flags & MSI_FLAG_MULTI_PCI_MSI))
                return 1;
        else if (desc->msi_attrib.is_msix && !(info->flags & MSI_FLAG_PCI_MSIX))
                return -ENOTSUPP;

        return 0;
}

static int pci_msi_domain_handle_error(struct irq_domain *domain,
                                       struct msi_desc *desc, int error)
{
        /* Special handling to support __pci_enable_msi_range() */
        if (pci_msi_desc_is_multi_msi(desc) && error == -ENOSPC)
                return 1;

        return error;
}

#ifdef GENERIC_MSI_DOMAIN_OPS
static void pci_msi_domain_set_desc(msi_alloc_info_t *arg,
                                    struct msi_desc *desc)
{
        arg->desc = desc;
        arg->hwirq = pci_msi_domain_calc_hwirq(msi_desc_to_pci_dev(desc),
                                               desc);
}
#else
#define pci_msi_domain_set_desc         NULL
#endif

static struct msi_domain_ops pci_msi_domain_ops_default = {
        .set_desc       = pci_msi_domain_set_desc,
        .msi_check      = pci_msi_domain_check_cap,
        .handle_error   = pci_msi_domain_handle_error,
};

static void pci_msi_domain_update_dom_ops(struct msi_domain_info *info)
{
        struct msi_domain_ops *ops = info->ops;

        if (ops == NULL) {
                info->ops = &pci_msi_domain_ops_default;
        } else {
                if (ops->set_desc == NULL)
                        ops->set_desc = pci_msi_domain_set_desc;
                if (ops->msi_check == NULL)
                        ops->msi_check = pci_msi_domain_check_cap;
                if (ops->handle_error == NULL)
                        ops->handle_error = pci_msi_domain_handle_error;
        }
}

static void pci_msi_domain_update_chip_ops(struct msi_domain_info *info)
{
        struct irq_chip *chip = info->chip;

        BUG_ON(!chip);
        if (!chip->irq_write_msi_msg)
                chip->irq_write_msi_msg = pci_msi_domain_write_msg;
        if (!chip->irq_mask)
                chip->irq_mask = pci_msi_mask_irq;
        if (!chip->irq_unmask)
                chip->irq_unmask = pci_msi_unmask_irq;
}

/**
 * pci_msi_create_irq_domain - Create a MSI interrupt domain
 * @fwnode:     Optional fwnode of the interrupt controller
 * @info:       MSI domain info
 * @parent:     Parent irq domain
 *
 * Updates the domain and chip ops and creates a MSI interrupt domain.
 *
 * Returns:
 * A domain pointer or NULL in case of failure.
 */
struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
                                             struct msi_domain_info *info,
                                             struct irq_domain *parent)
{
        struct irq_domain *domain;

        if (WARN_ON(info->flags & MSI_FLAG_LEVEL_CAPABLE))
                info->flags &= ~MSI_FLAG_LEVEL_CAPABLE;

        if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)
                pci_msi_domain_update_dom_ops(info);
        if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
                pci_msi_domain_update_chip_ops(info);

        info->flags |= MSI_FLAG_ACTIVATE_EARLY;
        if (IS_ENABLED(CONFIG_GENERIC_IRQ_RESERVATION_MODE))
                info->flags |= MSI_FLAG_MUST_REACTIVATE;

        /* PCI-MSI is oneshot-safe */
        info->chip->flags |= IRQCHIP_ONESHOT_SAFE;

        domain = msi_create_irq_domain(fwnode, info, parent);
        if (!domain)
                return NULL;

        irq_domain_update_bus_token(domain, DOMAIN_BUS_PCI_MSI);
        return domain;
}
EXPORT_SYMBOL_GPL(pci_msi_create_irq_domain);

/*
 * Users of the generic MSI infrastructure expect a device to have a single ID,
 * so with DMA aliases we have to pick the least-worst compromise. Devices with
 * DMA phantom functions tend to still emit MSIs from the real function number,
 * so we ignore those and only consider topological aliases where either the
 * alias device or RID appears on a different bus number. We also make the
 * reasonable assumption that bridges are walked in an upstream direction (so
 * the last one seen wins), and the much braver assumption that the most likely
 * case is that of PCI->PCIe so we should always use the alias RID. This echoes
 * the logic from intel_irq_remapping's set_msi_sid(), which presumably works
 * well enough in practice; in the face of the horrible PCIe<->PCI-X conditions
 * for taking ownership all we can really do is close our eyes and hope...
 */
static int get_msi_id_cb(struct pci_dev *pdev, u16 alias, void *data)
{
        u32 *pa = data;
        u8 bus = PCI_BUS_NUM(*pa);

        if (pdev->bus->number != bus || PCI_BUS_NUM(alias) != bus)
                *pa = alias;

        return 0;
}

/**
 * pci_msi_domain_get_msi_rid - Get the MSI requester id (RID)
 * @domain:     The interrupt domain
 * @pdev:       The PCI device.
 *
 * The RID for a device is formed from the alias, with a firmware
 * supplied mapping applied
 *
 * Returns: The RID.
 */
u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
{
        struct device_node *of_node;
        u32 rid = pci_dev_id(pdev);

        pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);

        of_node = irq_domain_get_of_node(domain);
        rid = of_node ? of_msi_map_rid(&pdev->dev, of_node, rid) :
                        iort_msi_map_rid(&pdev->dev, rid);

        return rid;
}

/**
 * pci_msi_get_device_domain - Get the MSI domain for a given PCI device
 * @pdev:       The PCI device
 *
 * Use the firmware data to find a device-specific MSI domain
 * (i.e. not one that is set as a default).
 *
 * Returns: The corresponding MSI domain or NULL if none has been found.
 */
struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
{
        struct irq_domain *dom;
        u32 rid = pci_dev_id(pdev);

        pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
        dom = of_msi_map_get_device_domain(&pdev->dev, rid);
        if (!dom)
                dom = iort_get_device_domain(&pdev->dev, rid);
        return dom;
}
#endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */