PCI/MSI: Rename __read_msi_msg() to __pci_read_msi_msg()

[deliverable/linux.git] / drivers / pci / msi.c

/*
 * File:        msi.c
 * Purpose:     PCI Message Signaled Interrupt (MSI)
 *
 * Copyright (C) 2003-2004 Intel
 * Copyright (C) Tom Long Nguyen (tom.l.nguyen@intel.com)
 */

#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/slab.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)


/* Arch hooks */

struct msi_controller * __weak pcibios_msi_controller(struct pci_dev *dev)
{
        return NULL;
}

static struct msi_controller *pci_msi_controller(struct pci_dev *dev)
{
        struct msi_controller *msi_ctrl = dev->bus->msi;

        if (msi_ctrl)
                return msi_ctrl;

        return pcibios_msi_controller(dev);
}

int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
{
        struct msi_controller *chip = pci_msi_controller(dev);
        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_desc *entry;
        int ret;

        /*
         * 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;

        list_for_each_entry(entry, &dev->msi_list, list) {
                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;

        list_for_each_entry(entry, &dev->msi_list, list)
                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) {
                list_for_each_entry(entry, &dev->msi_list, list) {
                        if (irq == entry->irq)
                                break;
                }
        } else if (dev->msi_enabled)  {
                entry = irq_get_msi_desc(irq);
        }

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

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

static void msi_set_enable(struct pci_dev *dev, int enable)
{
        u16 control;

        pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
        control &= ~PCI_MSI_FLAGS_ENABLE;
        if (enable)
                control |= PCI_MSI_FLAGS_ENABLE;
        pci_write_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, control);
}

static void msix_clear_and_set_ctrl(struct pci_dev *dev, u16 clear, u16 set)
{
        u16 ctrl;

        pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &ctrl);
        ctrl &= ~clear;
        ctrl |= set;
        pci_write_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, ctrl);
}

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 __msi_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(desc->dev, desc->mask_pos, mask_bits);

        return mask_bits;
}

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

/*
 * 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 __msix_mask_irq(struct msi_desc *desc, u32 flag)
{
        u32 mask_bits = desc->masked;
        unsigned offset = desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
                                                PCI_MSIX_ENTRY_VECTOR_CTRL;

        if (pci_msi_ignore_mask)
                return 0;

        mask_bits &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
        if (flag)
                mask_bits |= PCI_MSIX_ENTRY_CTRL_MASKBIT;
        writel(mask_bits, desc->mask_base + offset);

        return mask_bits;
}

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

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

void mask_msi_irq(struct irq_data *data)
{
        msi_set_mask_bit(data, 1);
}

void unmask_msi_irq(struct irq_data *data)
{
        msi_set_mask_bit(data, 0);
}

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

        list_for_each_entry(entry, &dev->msi_list, list)
                default_restore_msi_irq(dev, entry->irq);
}

void __pci_read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
        BUG_ON(entry->dev->current_state != PCI_D0);

        if (entry->msi_attrib.is_msix) {
                void __iomem *base = entry->mask_base +
                        entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;

                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 {
                struct pci_dev *dev = entry->dev;
                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 __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
        /* Assert that the cache is valid, assuming that
         * valid messages are not all-zeroes. */
        BUG_ON(!(entry->msg.address_hi | entry->msg.address_lo |
                 entry->msg.data));

        *msg = entry->msg;
}

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

        __get_cached_msi_msg(entry, msg);
}
EXPORT_SYMBOL_GPL(get_cached_msi_msg);

void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
        if (entry->dev->current_state != PCI_D0) {
                /* Don't touch the hardware now */
        } else if (entry->msi_attrib.is_msix) {
                void __iomem *base;
                base = entry->mask_base +
                        entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;

                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 {
                struct pci_dev *dev = entry->dev;
                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);
                }
        }
        entry->msg = *msg;
}

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

        __write_msi_msg(entry, msg);
}
EXPORT_SYMBOL_GPL(write_msi_msg);

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

        list_for_each_entry(entry, &dev->msi_list, list)
                if (entry->irq)
                        for (i = 0; i < entry->nvec_used; i++)
                                BUG_ON(irq_has_action(entry->irq + i));

        arch_teardown_msi_irqs(dev);

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

                list_del(&entry->list);
                kfree(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 struct msi_desc *alloc_msi_entry(struct pci_dev *dev)
{
        struct msi_desc *desc = kzalloc(sizeof(*desc), GFP_KERNEL);
        if (!desc)
                return NULL;

        INIT_LIST_HEAD(&desc->list);
        desc->dev = dev;

        return desc;
}

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);
        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->msi_list));

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

        arch_restore_msi_irqs(dev);
        list_for_each_entry(entry, &dev->msi_list, list)
                msix_mask_irq(entry, entry->masked);

        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;

        /* Determine how many msi entries we have */
        list_for_each_entry(entry, &pdev->msi_list, list)
                ++num_msi;
        if (!num_msi)
                return 0;

        /* Dynamically create the MSI attributes for the PCI device */
        msi_attrs = kzalloc(sizeof(void *) * (num_msi + 1), GFP_KERNEL);
        if (!msi_attrs)
                return -ENOMEM;
        list_for_each_entry(entry, &pdev->msi_list, list) {
                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);
                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 = kzalloc(sizeof(void *) * 2, 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)
{
        u16 control;
        struct msi_desc *entry;

        /* MSI Entry Initialization */
        entry = alloc_msi_entry(dev);
        if (!entry)
                return NULL;

        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.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));
        entry->nvec_used                = 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);

        return entry;
}

/**
 * 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
 *
 * 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 msi_desc *entry;
        int ret;
        unsigned mask;

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

        entry = msi_setup_entry(dev, nvec);
        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->msi_list);

        /* Configure MSI capability structure */
        ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
        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);
        msi_set_enable(dev, 1);
        dev->msi_enabled = 1;

        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;
        u8 bir;

        pci_read_config_dword(dev, dev->msix_cap + PCI_MSIX_TABLE,
                              &table_offset);
        bir = (u8)(table_offset & PCI_MSIX_TABLE_BIR);
        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 msi_desc *entry;
        int i;

        for (i = 0; i < nvec; i++) {
                entry = alloc_msi_entry(dev);
                if (!entry) {
                        if (!i)
                                iounmap(base);
                        else
                                free_msi_irqs(dev);
                        /* No enough memory. Don't try again */
                        return -ENOMEM;
                }

                entry->msi_attrib.is_msix       = 1;
                entry->msi_attrib.is_64         = 1;
                entry->msi_attrib.entry_nr      = entries[i].entry;
                entry->msi_attrib.default_irq   = dev->irq;
                entry->mask_base                = base;
                entry->nvec_used                = 1;

                list_add_tail(&entry->list, &dev->msi_list);
        }

        return 0;
}

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

        list_for_each_entry(entry, &dev->msi_list, list) {
                int offset = entries[i].entry * PCI_MSIX_ENTRY_SIZE +
                                                PCI_MSIX_ENTRY_VECTOR_CTRL;

                entries[i].vector = entry->irq;
                entry->masked = readl(entry->mask_base + offset);
                msix_mask_irq(entry, 1);
                i++;
        }
}

/**
 * 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
 *
 * 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)
{
        int ret;
        u16 control;
        void __iomem *base;

        /* Ensure MSI-X is disabled while it is set up */
        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);
        if (ret)
                return ret;

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

        /*
         * 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.
         */
        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;

        msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);

        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;

                list_for_each_entry(entry, &dev->msi_list, list) {
                        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);

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->msi_list));
        desc = list_first_entry(&dev->msi_list, struct msi_desc, list);

        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 */
        __msi_mask_irq(desc, mask, ~mask);

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

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);

/**
 * pci_enable_msix - 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
 * @nvec: number of MSI-X irqs requested for allocation by device driver
 *
 * Setup the MSI-X capability structure of device function with the number
 * of requested irqs upon its software driver call to request for
 * MSI-X mode enabled on its hardware device function. A return of zero
 * indicates the successful configuration of MSI-X capability structure
 * with new allocated MSI-X irqs. A return of < 0 indicates a failure.
 * Or a return of > 0 indicates that driver request is exceeding the number
 * of irqs or MSI-X vectors available. Driver should use the returned value to
 * re-send its request.
 **/
int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
{
        int nr_entries;
        int i, j;

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

        if (!entries)
                return -EINVAL;

        nr_entries = pci_msix_vec_count(dev);
        if (nr_entries < 0)
                return nr_entries;
        if (nvec > nr_entries)
                return nr_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 */
                }
        }
        WARN_ON(!!dev->msix_enabled);

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

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

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

        /* Return the device with MSI-X masked as initial states */
        list_for_each_entry(entry, &dev->msi_list, list) {
                /* Keep cached states to be restored */
                __msix_mask_irq(entry, 1);
        }

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

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);

void pci_msi_init_pci_dev(struct pci_dev *dev)
{
        INIT_LIST_HEAD(&dev->msi_list);

        /* Disable the msi hardware to avoid screaming interrupts
         * during boot.  This is the power on reset default so
         * usually this should be a noop.
         */
        dev->msi_cap = pci_find_capability(dev, PCI_CAP_ID_MSI);
        if (dev->msi_cap)
                msi_set_enable(dev, 0);

        dev->msix_cap = pci_find_capability(dev, PCI_CAP_ID_MSIX);
        if (dev->msix_cap)
                msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
}

/**
 * pci_enable_msi_range - configure device's MSI capability structure
 * @dev: device to configure
 * @minvec: minimal number of interrupts to configure
 * @maxvec: maximum number of interrupts to configure
 *
 * This function tries to allocate a maximum possible number of interrupts in a
 * range between @minvec and @maxvec. It returns a negative errno if an error
 * occurs. If it succeeds, it returns the actual number of interrupts allocated
 * and updates the @dev's irq member to the lowest new interrupt number;
 * the other interrupt numbers allocated to this device are consecutive.
 **/
int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec)
{
        int nvec;
        int rc;

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

        WARN_ON(!!dev->msi_enabled);

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

        if (maxvec < minvec)
                return -ERANGE;

        nvec = pci_msi_vec_count(dev);
        if (nvec < 0)
                return nvec;
        else if (nvec < minvec)
                return -EINVAL;
        else if (nvec > maxvec)
                nvec = maxvec;

        do {
                rc = msi_capability_init(dev, nvec);
                if (rc < 0) {
                        return rc;
                } else if (rc > 0) {
                        if (rc < minvec)
                                return -ENOSPC;
                        nvec = rc;
                }
        } while (rc);

        return nvec;
}
EXPORT_SYMBOL(pci_enable_msi_range);

/**
 * 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)
{
        int nvec = maxvec;
        int rc;

        if (maxvec < minvec)
                return -ERANGE;

        do {
                rc = pci_enable_msix(dev, entries, nvec);
                if (rc < 0) {
                        return rc;
                } else if (rc > 0) {
                        if (rc < minvec)
                                return -ENOSPC;
                        nvec = rc;
                }
        } while (rc);

        return nvec;
}
EXPORT_SYMBOL(pci_enable_msix_range);