pci-driver.c

Go to the documentation of this file.

/*
 * drivers/pci/pci-driver.c
 *
 * (C) Copyright 2002-2004, 2007 Greg Kroah-Hartman <[email protected]>
 * (C) Copyright 2007 Novell Inc.
 *
 * Released under the GPL v2 only.
 *
 */

#include <linux/pci.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/mempolicy.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/cpu.h>
#include <linux/pm_runtime.h>
#include <linux/suspend.h>
#include "pci.h"

struct pci_dynid {
    struct list_head node;
    struct pci_device_id id;
};

int pci_add_dynid(struct pci_driver *drv,
          unsigned int vendor, unsigned int device,
          unsigned int subvendor, unsigned int subdevice,
          unsigned int class, unsigned int class_mask,
          unsigned long driver_data)
{
    struct pci_dynid *dynid;
    int retval;

    dynid = kzalloc(sizeof(*dynid), GFP_KERNEL);
    if (!dynid)
        return -ENOMEM;

    dynid->id.vendor = vendor;
    dynid->id.device = device;
    dynid->id.subvendor = subvendor;
    dynid->id.subdevice = subdevice;
    dynid->id.class = class;
    dynid->id.class_mask = class_mask;
    dynid->id.driver_data = driver_data;

    spin_lock(&drv->dynids.lock);
    list_add_tail(&dynid->node, &drv->dynids.list);
    spin_unlock(&drv->dynids.lock);

    retval = driver_attach(&drv->driver);

    return retval;
}

static void pci_free_dynids(struct pci_driver *drv)
{
    struct pci_dynid *dynid, *n;

    spin_lock(&drv->dynids.lock);
    list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
        list_del(&dynid->node);
        kfree(dynid);
    }
    spin_unlock(&drv->dynids.lock);
}

/*
 * Dynamic device ID manipulation via sysfs is disabled for !CONFIG_HOTPLUG
 */
#ifdef CONFIG_HOTPLUG

static ssize_t
store_new_id(struct device_driver *driver, const char *buf, size_t count)
{
    struct pci_driver *pdrv = to_pci_driver(driver);
    const struct pci_device_id *ids = pdrv->id_table;
    __u32 vendor, device, subvendor=PCI_ANY_ID,
        subdevice=PCI_ANY_ID, class=0, class_mask=0;
    unsigned long driver_data=0;
    int fields=0;
    int retval;

    fields = sscanf(buf, "%x %x %x %x %x %x %lx",
            &vendor, &device, &subvendor, &subdevice,
            &class, &class_mask, &driver_data);
    if (fields < 2)
        return -EINVAL;

    /* Only accept driver_data values that match an existing id_table
       entry */
    if (ids) {
        retval = -EINVAL;
        while (ids->vendor || ids->subvendor || ids->class_mask) {
            if (driver_data == ids->driver_data) {
                retval = 0;
                break;
            }
            ids++;
        }
        if (retval) /* No match */
            return retval;
    }

    retval = pci_add_dynid(pdrv, vendor, device, subvendor, subdevice,
                   class, class_mask, driver_data);
    if (retval)
        return retval;
    return count;
}

static ssize_t
store_remove_id(struct device_driver *driver, const char *buf, size_t count)
{
    struct pci_dynid *dynid, *n;
    struct pci_driver *pdrv = to_pci_driver(driver);
    __u32 vendor, device, subvendor = PCI_ANY_ID,
        subdevice = PCI_ANY_ID, class = 0, class_mask = 0;
    int fields = 0;
    int retval = -ENODEV;

    fields = sscanf(buf, "%x %x %x %x %x %x",
            &vendor, &device, &subvendor, &subdevice,
            &class, &class_mask);
    if (fields < 2)
        return -EINVAL;

    spin_lock(&pdrv->dynids.lock);
    list_for_each_entry_safe(dynid, n, &pdrv->dynids.list, node) {
        struct pci_device_id *id = &dynid->id;
        if ((id->vendor == vendor) &&
            (id->device == device) &&
            (subvendor == PCI_ANY_ID || id->subvendor == subvendor) &&
            (subdevice == PCI_ANY_ID || id->subdevice == subdevice) &&
            !((id->class ^ class) & class_mask)) {
            list_del(&dynid->node);
            kfree(dynid);
            retval = 0;
            break;
        }
    }
    spin_unlock(&pdrv->dynids.lock);

    if (retval)
        return retval;
    return count;
}

static struct driver_attribute pci_drv_attrs[] = {
    __ATTR(new_id, S_IWUSR, NULL, store_new_id),
    __ATTR(remove_id, S_IWUSR, NULL, store_remove_id),
    __ATTR_NULL,
};

#else
#define pci_drv_attrs   NULL
#endif /* CONFIG_HOTPLUG */

const struct pci_device_id *pci_match_id(const struct pci_device_id *ids,
                     struct pci_dev *dev)
{
    if (ids) {
        while (ids->vendor || ids->subvendor || ids->class_mask) {
            if (pci_match_one_device(ids, dev))
                return ids;
            ids++;
        }
    }
    return NULL;
}

static const struct pci_device_id *pci_match_device(struct pci_driver *drv,
                            struct pci_dev *dev)
{
    struct pci_dynid *dynid;

    /* Look at the dynamic ids first, before the static ones */
    spin_lock(&drv->dynids.lock);
    list_for_each_entry(dynid, &drv->dynids.list, node) {
        if (pci_match_one_device(&dynid->id, dev)) {
            spin_unlock(&drv->dynids.lock);
            return &dynid->id;
        }
    }
    spin_unlock(&drv->dynids.lock);

    return pci_match_id(drv->id_table, dev);
}

struct drv_dev_and_id {
    struct pci_driver *drv;
    struct pci_dev *dev;
    const struct pci_device_id *id;
};

static long local_pci_probe(void *_ddi)
{
    struct drv_dev_and_id *ddi = _ddi;
    struct device *dev = &ddi->dev->dev;
    struct device *parent = dev->parent;
    int rc;

    /* The parent bridge must be in active state when probing */
    if (parent)
        pm_runtime_get_sync(parent);
    /* Unbound PCI devices are always set to disabled and suspended.
     * During probe, the device is set to enabled and active and the
     * usage count is incremented.  If the driver supports runtime PM,
     * it should call pm_runtime_put_noidle() in its probe routine and
     * pm_runtime_get_noresume() in its remove routine.
     */
    pm_runtime_get_noresume(dev);
    pm_runtime_set_active(dev);
    pm_runtime_enable(dev);

    rc = ddi->drv->probe(ddi->dev, ddi->id);
    if (rc) {
        pm_runtime_disable(dev);
        pm_runtime_set_suspended(dev);
        pm_runtime_put_noidle(dev);
    }
    if (parent)
        pm_runtime_put(parent);
    return rc;
}

static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
              const struct pci_device_id *id)
{
    int error, node;
    struct drv_dev_and_id ddi = { drv, dev, id };

    /* Execute driver initialization on node where the device's
       bus is attached to.  This way the driver likely allocates
       its local memory on the right node without any need to
       change it. */
    node = dev_to_node(&dev->dev);
    if (node >= 0) {
        int cpu;

        get_online_cpus();
        cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
        if (cpu < nr_cpu_ids)
            error = work_on_cpu(cpu, local_pci_probe, &ddi);
        else
            error = local_pci_probe(&ddi);
        put_online_cpus();
    } else
        error = local_pci_probe(&ddi);
    return error;
}

static int
__pci_device_probe(struct pci_driver *drv, struct pci_dev *pci_dev)
{
    const struct pci_device_id *id;
    int error = 0;

    if (!pci_dev->driver && drv->probe) {
        error = -ENODEV;

        id = pci_match_device(drv, pci_dev);
        if (id)
            error = pci_call_probe(drv, pci_dev, id);
        if (error >= 0) {
            pci_dev->driver = drv;
            error = 0;
        }
    }
    return error;
}

static int pci_device_probe(struct device * dev)
{
    int error = 0;
    struct pci_driver *drv;
    struct pci_dev *pci_dev;

    drv = to_pci_driver(dev->driver);
    pci_dev = to_pci_dev(dev);
    pci_dev_get(pci_dev);
    error = __pci_device_probe(drv, pci_dev);
    if (error)
        pci_dev_put(pci_dev);

    return error;
}

static int pci_device_remove(struct device * dev)
{
    struct pci_dev * pci_dev = to_pci_dev(dev);
    struct pci_driver * drv = pci_dev->driver;

    if (drv) {
        if (drv->remove) {
            pm_runtime_get_sync(dev);
            drv->remove(pci_dev);
            pm_runtime_put_noidle(dev);
        }
        pci_dev->driver = NULL;
    }

    /* Undo the runtime PM settings in local_pci_probe() */
    pm_runtime_disable(dev);
    pm_runtime_set_suspended(dev);
    pm_runtime_put_noidle(dev);

    /*
     * If the device is still on, set the power state as "unknown",
     * since it might change by the next time we load the driver.
     */
    if (pci_dev->current_state == PCI_D0)
        pci_dev->current_state = PCI_UNKNOWN;

    /*
     * We would love to complain here if pci_dev->is_enabled is set, that
     * the driver should have called pci_disable_device(), but the
     * unfortunate fact is there are too many odd BIOS and bridge setups
     * that don't like drivers doing that all of the time.  
     * Oh well, we can dream of sane hardware when we sleep, no matter how
     * horrible the crap we have to deal with is when we are awake...
     */

    pci_dev_put(pci_dev);
    return 0;
}

static void pci_device_shutdown(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct pci_driver *drv = pci_dev->driver;

    pm_runtime_resume(dev);

    if (drv && drv->shutdown)
        drv->shutdown(pci_dev);
    pci_msi_shutdown(pci_dev);
    pci_msix_shutdown(pci_dev);

    /*
     * Turn off Bus Master bit on the device to tell it to not
     * continue to do DMA
     */
    pci_disable_device(pci_dev);
}

#ifdef CONFIG_PM

/* Auxiliary functions used for system resume and run-time resume. */

static int pci_restore_standard_config(struct pci_dev *pci_dev)
{
    pci_update_current_state(pci_dev, PCI_UNKNOWN);

    if (pci_dev->current_state != PCI_D0) {
        int error = pci_set_power_state(pci_dev, PCI_D0);
        if (error)
            return error;
    }

    pci_restore_state(pci_dev);
    return 0;
}

#endif

#ifdef CONFIG_PM_SLEEP

static void pci_pm_default_resume_early(struct pci_dev *pci_dev)
{
    pci_power_up(pci_dev);
    pci_restore_state(pci_dev);
    pci_fixup_device(pci_fixup_resume_early, pci_dev);
}

/*
 * Default "suspend" method for devices that have no driver provided suspend,
 * or not even a driver at all (second part).
 */
static void pci_pm_set_unknown_state(struct pci_dev *pci_dev)
{
    /*
     * mark its power state as "unknown", since we don't know if
     * e.g. the BIOS will change its device state when we suspend.
     */
    if (pci_dev->current_state == PCI_D0)
        pci_dev->current_state = PCI_UNKNOWN;
}

/*
 * Default "resume" method for devices that have no driver provided resume,
 * or not even a driver at all (second part).
 */
static int pci_pm_reenable_device(struct pci_dev *pci_dev)
{
    int retval;

    /* if the device was enabled before suspend, reenable */
    retval = pci_reenable_device(pci_dev);
    /*
     * if the device was busmaster before the suspend, make it busmaster
     * again
     */
    if (pci_dev->is_busmaster)
        pci_set_master(pci_dev);

    return retval;
}

static int pci_legacy_suspend(struct device *dev, pm_message_t state)
{
    struct pci_dev * pci_dev = to_pci_dev(dev);
    struct pci_driver * drv = pci_dev->driver;

    if (drv && drv->suspend) {
        pci_power_t prev = pci_dev->current_state;
        int error;

        error = drv->suspend(pci_dev, state);
        suspend_report_result(drv->suspend, error);
        if (error)
            return error;

        if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
            && pci_dev->current_state != PCI_UNKNOWN) {
            WARN_ONCE(pci_dev->current_state != prev,
                "PCI PM: Device state not saved by %pF\n",
                drv->suspend);
        }
    }

    pci_fixup_device(pci_fixup_suspend, pci_dev);

    return 0;
}

static int pci_legacy_suspend_late(struct device *dev, pm_message_t state)
{
    struct pci_dev * pci_dev = to_pci_dev(dev);
    struct pci_driver * drv = pci_dev->driver;

    if (drv && drv->suspend_late) {
        pci_power_t prev = pci_dev->current_state;
        int error;

        error = drv->suspend_late(pci_dev, state);
        suspend_report_result(drv->suspend_late, error);
        if (error)
            return error;

        if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
            && pci_dev->current_state != PCI_UNKNOWN) {
            WARN_ONCE(pci_dev->current_state != prev,
                "PCI PM: Device state not saved by %pF\n",
                drv->suspend_late);
            return 0;
        }
    }

    if (!pci_dev->state_saved)
        pci_save_state(pci_dev);

    pci_pm_set_unknown_state(pci_dev);

    return 0;
}

static int pci_legacy_resume_early(struct device *dev)
{
    struct pci_dev * pci_dev = to_pci_dev(dev);
    struct pci_driver * drv = pci_dev->driver;

    return drv && drv->resume_early ?
            drv->resume_early(pci_dev) : 0;
}

static int pci_legacy_resume(struct device *dev)
{
    struct pci_dev * pci_dev = to_pci_dev(dev);
    struct pci_driver * drv = pci_dev->driver;

    pci_fixup_device(pci_fixup_resume, pci_dev);

    return drv && drv->resume ?
            drv->resume(pci_dev) : pci_pm_reenable_device(pci_dev);
}

/* Auxiliary functions used by the new power management framework */

static void pci_pm_default_resume(struct pci_dev *pci_dev)
{
    pci_fixup_device(pci_fixup_resume, pci_dev);

    if (!pci_is_bridge(pci_dev))
        pci_enable_wake(pci_dev, PCI_D0, false);
}

static void pci_pm_default_suspend(struct pci_dev *pci_dev)
{
    /* Disable non-bridge devices without PM support */
    if (!pci_is_bridge(pci_dev))
        pci_disable_enabled_device(pci_dev);
}

static bool pci_has_legacy_pm_support(struct pci_dev *pci_dev)
{
    struct pci_driver *drv = pci_dev->driver;
    bool ret = drv && (drv->suspend || drv->suspend_late || drv->resume
        || drv->resume_early);

    /*
     * Legacy PM support is used by default, so warn if the new framework is
     * supported as well.  Drivers are supposed to support either the
     * former, or the latter, but not both at the same time.
     */
    WARN(ret && drv->driver.pm, "driver %s device %04x:%04x\n",
        drv->name, pci_dev->vendor, pci_dev->device);

    return ret;
}

/* New power management framework */

static int pci_pm_prepare(struct device *dev)
{
    struct device_driver *drv = dev->driver;
    int error = 0;

    /*
     * PCI devices suspended at run time need to be resumed at this
     * point, because in general it is necessary to reconfigure them for
     * system suspend.  Namely, if the device is supposed to wake up the
     * system from the sleep state, we may need to reconfigure it for this
     * purpose.  In turn, if the device is not supposed to wake up the
     * system from the sleep state, we'll have to prevent it from signaling
     * wake-up.
     */
    pm_runtime_resume(dev);

    if (drv && drv->pm && drv->pm->prepare)
        error = drv->pm->prepare(dev);

    return error;
}

static void pci_pm_complete(struct device *dev)
{
    struct device_driver *drv = dev->driver;

    if (drv && drv->pm && drv->pm->complete)
        drv->pm->complete(dev);
}

#else /* !CONFIG_PM_SLEEP */

#define pci_pm_prepare  NULL
#define pci_pm_complete NULL

#endif /* !CONFIG_PM_SLEEP */

#ifdef CONFIG_SUSPEND

static int pci_pm_suspend(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_suspend(dev, PMSG_SUSPEND);

    if (!pm) {
        pci_pm_default_suspend(pci_dev);
        goto Fixup;
    }

    if (pm->suspend) {
        pci_power_t prev = pci_dev->current_state;
        int error;

        error = pm->suspend(dev);
        suspend_report_result(pm->suspend, error);
        if (error)
            return error;

        if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
            && pci_dev->current_state != PCI_UNKNOWN) {
            WARN_ONCE(pci_dev->current_state != prev,
                "PCI PM: State of device not saved by %pF\n",
                pm->suspend);
        }
    }

 Fixup:
    pci_fixup_device(pci_fixup_suspend, pci_dev);

    return 0;
}

static int pci_pm_suspend_noirq(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_suspend_late(dev, PMSG_SUSPEND);

    if (!pm) {
        pci_save_state(pci_dev);
        return 0;
    }

    if (pm->suspend_noirq) {
        pci_power_t prev = pci_dev->current_state;
        int error;

        error = pm->suspend_noirq(dev);
        suspend_report_result(pm->suspend_noirq, error);
        if (error)
            return error;

        if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
            && pci_dev->current_state != PCI_UNKNOWN) {
            WARN_ONCE(pci_dev->current_state != prev,
                "PCI PM: State of device not saved by %pF\n",
                pm->suspend_noirq);
            return 0;
        }
    }

    if (!pci_dev->state_saved) {
        pci_save_state(pci_dev);
        if (!pci_is_bridge(pci_dev))
            pci_prepare_to_sleep(pci_dev);
    }

    pci_pm_set_unknown_state(pci_dev);

    /*
     * Some BIOSes from ASUS have a bug: If a USB EHCI host controller's
     * PCI COMMAND register isn't 0, the BIOS assumes that the controller
     * hasn't been quiesced and tries to turn it off.  If the controller
     * is already in D3, this can hang or cause memory corruption.
     *
     * Since the value of the COMMAND register doesn't matter once the
     * device has been suspended, we can safely set it to 0 here.
     */
    if (pci_dev->class == PCI_CLASS_SERIAL_USB_EHCI)
        pci_write_config_word(pci_dev, PCI_COMMAND, 0);

    return 0;
}

static int pci_pm_resume_noirq(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct device_driver *drv = dev->driver;
    int error = 0;

    pci_pm_default_resume_early(pci_dev);

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_resume_early(dev);

    if (drv && drv->pm && drv->pm->resume_noirq)
        error = drv->pm->resume_noirq(dev);

    return error;
}

static int pci_pm_resume(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
    int error = 0;

    /*
     * This is necessary for the suspend error path in which resume is
     * called without restoring the standard config registers of the device.
     */
    if (pci_dev->state_saved)
        pci_restore_standard_config(pci_dev);

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_resume(dev);

    pci_pm_default_resume(pci_dev);

    if (pm) {
        if (pm->resume)
            error = pm->resume(dev);
    } else {
        pci_pm_reenable_device(pci_dev);
    }

    return error;
}

#else /* !CONFIG_SUSPEND */

#define pci_pm_suspend      NULL
#define pci_pm_suspend_noirq    NULL
#define pci_pm_resume       NULL
#define pci_pm_resume_noirq NULL

#endif /* !CONFIG_SUSPEND */

#ifdef CONFIG_HIBERNATE_CALLBACKS

static int pci_pm_freeze(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_suspend(dev, PMSG_FREEZE);

    if (!pm) {
        pci_pm_default_suspend(pci_dev);
        return 0;
    }

    if (pm->freeze) {
        int error;

        error = pm->freeze(dev);
        suspend_report_result(pm->freeze, error);
        if (error)
            return error;
    }

    return 0;
}

static int pci_pm_freeze_noirq(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct device_driver *drv = dev->driver;

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_suspend_late(dev, PMSG_FREEZE);

    if (drv && drv->pm && drv->pm->freeze_noirq) {
        int error;

        error = drv->pm->freeze_noirq(dev);
        suspend_report_result(drv->pm->freeze_noirq, error);
        if (error)
            return error;
    }

    if (!pci_dev->state_saved)
        pci_save_state(pci_dev);

    pci_pm_set_unknown_state(pci_dev);

    return 0;
}

static int pci_pm_thaw_noirq(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct device_driver *drv = dev->driver;
    int error = 0;

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_resume_early(dev);

    pci_update_current_state(pci_dev, PCI_D0);

    if (drv && drv->pm && drv->pm->thaw_noirq)
        error = drv->pm->thaw_noirq(dev);

    return error;
}

static int pci_pm_thaw(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
    int error = 0;

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_resume(dev);

    if (pm) {
        if (pm->thaw)
            error = pm->thaw(dev);
    } else {
        pci_pm_reenable_device(pci_dev);
    }

    pci_dev->state_saved = false;

    return error;
}

static int pci_pm_poweroff(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_suspend(dev, PMSG_HIBERNATE);

    if (!pm) {
        pci_pm_default_suspend(pci_dev);
        goto Fixup;
    }

    if (pm->poweroff) {
        int error;

        error = pm->poweroff(dev);
        suspend_report_result(pm->poweroff, error);
        if (error)
            return error;
    }

 Fixup:
    pci_fixup_device(pci_fixup_suspend, pci_dev);

    return 0;
}

static int pci_pm_poweroff_noirq(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct device_driver *drv = dev->driver;

    if (pci_has_legacy_pm_support(to_pci_dev(dev)))
        return pci_legacy_suspend_late(dev, PMSG_HIBERNATE);

    if (!drv || !drv->pm)
        return 0;

    if (drv->pm->poweroff_noirq) {
        int error;

        error = drv->pm->poweroff_noirq(dev);
        suspend_report_result(drv->pm->poweroff_noirq, error);
        if (error)
            return error;
    }

    if (!pci_dev->state_saved && !pci_is_bridge(pci_dev))
        pci_prepare_to_sleep(pci_dev);

    /*
     * The reason for doing this here is the same as for the analogous code
     * in pci_pm_suspend_noirq().
     */
    if (pci_dev->class == PCI_CLASS_SERIAL_USB_EHCI)
        pci_write_config_word(pci_dev, PCI_COMMAND, 0);

    return 0;
}

static int pci_pm_restore_noirq(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct device_driver *drv = dev->driver;
    int error = 0;

    pci_pm_default_resume_early(pci_dev);

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_resume_early(dev);

    if (drv && drv->pm && drv->pm->restore_noirq)
        error = drv->pm->restore_noirq(dev);

    return error;
}

static int pci_pm_restore(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
    int error = 0;

    /*
     * This is necessary for the hibernation error path in which restore is
     * called without restoring the standard config registers of the device.
     */
    if (pci_dev->state_saved)
        pci_restore_standard_config(pci_dev);

    if (pci_has_legacy_pm_support(pci_dev))
        return pci_legacy_resume(dev);

    pci_pm_default_resume(pci_dev);

    if (pm) {
        if (pm->restore)
            error = pm->restore(dev);
    } else {
        pci_pm_reenable_device(pci_dev);
    }

    return error;
}

#else /* !CONFIG_HIBERNATE_CALLBACKS */

#define pci_pm_freeze       NULL
#define pci_pm_freeze_noirq NULL
#define pci_pm_thaw     NULL
#define pci_pm_thaw_noirq   NULL
#define pci_pm_poweroff     NULL
#define pci_pm_poweroff_noirq   NULL
#define pci_pm_restore      NULL
#define pci_pm_restore_noirq    NULL

#endif /* !CONFIG_HIBERNATE_CALLBACKS */

#ifdef CONFIG_PM_RUNTIME

static int pci_pm_runtime_suspend(struct device *dev)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
    pci_power_t prev = pci_dev->current_state;
    int error;

    if (!pm || !pm->runtime_suspend)
        return -ENOSYS;

    pci_dev->no_d3cold = false;
    error = pm->runtime_suspend(dev);
    suspend_report_result(pm->runtime_suspend, error);
    if (error)
        return error;
    if (!pci_dev->d3cold_allowed)
        pci_dev->no_d3cold = true;

    pci_fixup_device(pci_fixup_suspend, pci_dev);

    if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
        && pci_dev->current_state != PCI_UNKNOWN) {
        WARN_ONCE(pci_dev->current_state != prev,
            "PCI PM: State of device not saved by %pF\n",
            pm->runtime_suspend);
        return 0;
    }

    if (!pci_dev->state_saved)
        pci_save_state(pci_dev);

    pci_finish_runtime_suspend(pci_dev);

    return 0;
}

static int pci_pm_runtime_resume(struct device *dev)
{
    int rc;
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

    if (!pm || !pm->runtime_resume)
        return -ENOSYS;

    pci_restore_standard_config(pci_dev);
    pci_fixup_device(pci_fixup_resume_early, pci_dev);
    __pci_enable_wake(pci_dev, PCI_D0, true, false);
    pci_fixup_device(pci_fixup_resume, pci_dev);

    rc = pm->runtime_resume(dev);

    pci_dev->runtime_d3cold = false;

    return rc;
}

static int pci_pm_runtime_idle(struct device *dev)
{
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

    if (!pm)
        return -ENOSYS;

    if (pm->runtime_idle) {
        int ret = pm->runtime_idle(dev);
        if (ret)
            return ret;
    }

    pm_runtime_suspend(dev);

    return 0;
}

#else /* !CONFIG_PM_RUNTIME */

#define pci_pm_runtime_suspend  NULL
#define pci_pm_runtime_resume   NULL
#define pci_pm_runtime_idle NULL

#endif /* !CONFIG_PM_RUNTIME */

#ifdef CONFIG_PM

const struct dev_pm_ops pci_dev_pm_ops = {
    .prepare = pci_pm_prepare,
    .complete = pci_pm_complete,
    .suspend = pci_pm_suspend,
    .resume = pci_pm_resume,
    .freeze = pci_pm_freeze,
    .thaw = pci_pm_thaw,
    .poweroff = pci_pm_poweroff,
    .restore = pci_pm_restore,
    .suspend_noirq = pci_pm_suspend_noirq,
    .resume_noirq = pci_pm_resume_noirq,
    .freeze_noirq = pci_pm_freeze_noirq,
    .thaw_noirq = pci_pm_thaw_noirq,
    .poweroff_noirq = pci_pm_poweroff_noirq,
    .restore_noirq = pci_pm_restore_noirq,
    .runtime_suspend = pci_pm_runtime_suspend,
    .runtime_resume = pci_pm_runtime_resume,
    .runtime_idle = pci_pm_runtime_idle,
};

#define PCI_PM_OPS_PTR  (&pci_dev_pm_ops)

#else /* !COMFIG_PM_OPS */

#define PCI_PM_OPS_PTR  NULL

#endif /* !COMFIG_PM_OPS */

int __pci_register_driver(struct pci_driver *drv, struct module *owner,
              const char *mod_name)
{
    /* initialize common driver fields */
    drv->driver.name = drv->name;
    drv->driver.bus = &pci_bus_type;
    drv->driver.owner = owner;
    drv->driver.mod_name = mod_name;

    spin_lock_init(&drv->dynids.lock);
    INIT_LIST_HEAD(&drv->dynids.list);

    /* register with core */
    return driver_register(&drv->driver);
}

void
pci_unregister_driver(struct pci_driver *drv)
{
    driver_unregister(&drv->driver);
    pci_free_dynids(drv);
}

static struct pci_driver pci_compat_driver = {
    .name = "compat"
};

struct pci_driver *
pci_dev_driver(const struct pci_dev *dev)
{
    if (dev->driver)
        return dev->driver;
    else {
        int i;
        for(i=0; i<=PCI_ROM_RESOURCE; i++)
            if (dev->resource[i].flags & IORESOURCE_BUSY)
                return &pci_compat_driver;
    }
    return NULL;
}

static int pci_bus_match(struct device *dev, struct device_driver *drv)
{
    struct pci_dev *pci_dev = to_pci_dev(dev);
    struct pci_driver *pci_drv = to_pci_driver(drv);
    const struct pci_device_id *found_id;

    found_id = pci_match_device(pci_drv, pci_dev);
    if (found_id)
        return 1;

    return 0;
}

struct pci_dev *pci_dev_get(struct pci_dev *dev)
{
    if (dev)
        get_device(&dev->dev);
    return dev;
}

void pci_dev_put(struct pci_dev *dev)
{
    if (dev)
        put_device(&dev->dev);
}

#ifndef CONFIG_HOTPLUG
int pci_uevent(struct device *dev, struct kobj_uevent_env *env)
{
    return -ENODEV;
}
#endif

struct bus_type pci_bus_type = {
    .name       = "pci",
    .match      = pci_bus_match,
    .uevent     = pci_uevent,
    .probe      = pci_device_probe,
    .remove     = pci_device_remove,
    .shutdown   = pci_device_shutdown,
    .dev_attrs  = pci_dev_attrs,
    .bus_attrs  = pci_bus_attrs,
    .drv_attrs  = pci_drv_attrs,
    .pm     = PCI_PM_OPS_PTR,
};

static int __init pci_driver_init(void)
{
    return bus_register(&pci_bus_type);
}

postcore_initcall(pci_driver_init);

EXPORT_SYMBOL_GPL(pci_add_dynid);
EXPORT_SYMBOL(pci_match_id);
EXPORT_SYMBOL(__pci_register_driver);
EXPORT_SYMBOL(pci_unregister_driver);
EXPORT_SYMBOL(pci_dev_driver);
EXPORT_SYMBOL(pci_bus_type);
EXPORT_SYMBOL(pci_dev_get);
EXPORT_SYMBOL(pci_dev_put);