/**
 * Copyright (c) 2014 Himanshu Chauhan.
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * @file pci-driver.c
 * @author Himanshu Chauhan (hschauhan@nulltrace.org)
 *
 * All the work under drivers/pci/ is a derived work from Linux's
 * PCI Framework. The following is the commit ID from which it has
 * been derived.
 *
 * commit 97bf6af1f928216fd6c5a66e8a57bfa95a659672
 * Linux 3.19-rc1
 *
 * drivers/pci/pci-driver.c
 *
 * (C) Copyright 2002-2004, 2007 Greg Kroah-Hartman <greg@kroah.com>
 * (C) Copyright 2007 Novell Inc.
 *
 * Released under the GPL v2 only.
 *
 */

#include <vmm_error.h>
#include <vmm_modules.h>
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/sched.h>
#include "pci.h"

#define MODULE_NAME			pci_core
#define MODULE_DESC			"PCI Host Core Framework"
#define MODULE_AUTHOR			"Himanshu Chauhan"
#define MODULE_LICENSE			"GPL"
#define MODULE_IPRIORITY		PCI_CORE_IPRIORITY
#define	MODULE_INIT			pci_core_init
#define	MODULE_EXIT			pci_core_exit

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

/**
 * pci_add_dynid - add a new PCI device ID to this driver and re-probe devices
 * @drv: target pci driver
 * @vendor: PCI vendor ID
 * @device: PCI device ID
 * @subvendor: PCI subvendor ID
 * @subdevice: PCI subdevice ID
 * @class: PCI class
 * @class_mask: PCI class mask
 * @driver_data: private driver data
 *
 * Adds a new dynamic pci device ID to this driver and causes the
 * driver to probe for all devices again.  @drv must have been
 * registered prior to calling this function.
 *
 * CONTEXT:
 * Does GFP_KERNEL allocation.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
int pci_add_dynid(struct pci_driver *drv,
		  unsigned int vendor, unsigned int devid,
		  unsigned int subvendor, unsigned int subdevice,
		  unsigned int class, unsigned int class_mask,
		  unsigned long driver_data)
{
	struct pci_dynid *dynid;

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

	dynid->id.vendor = vendor;

	dynid->id.devid = devid;
	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);

	return driver_attach(&drv->driver);
}
EXPORT_SYMBOL_GPL(pci_add_dynid);

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);
}

/**
 * pci_match_id - See if a pci device matches a given pci_id table
 * @ids: array of PCI device id structures to search in
 * @dev: the PCI device structure to match against.
 *
 * Used by a driver to check whether a PCI device present in the
 * system is in its list of supported devices.  Returns the matching
 * pci_device_id structure or %NULL if there is no match.
 *
 * Deprecated, don't use this as it will not catch any dynamic ids
 * that a driver might want to check for.
 */
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;
}
EXPORT_SYMBOL(pci_match_id);

static const struct pci_device_id pci_device_id_any = {
	.vendor = PCI_ANY_ID,
	.devid = PCI_ANY_ID,
	.subvendor = PCI_ANY_ID,
	.subdevice = PCI_ANY_ID,
};

/**
 * pci_match_device - Tell if a PCI device structure has a matching PCI device id structure
 * @drv: the PCI driver to match against
 * @dev: the PCI device structure to match against
 *
 * Used by a driver to check whether a PCI device present in the
 * system is in its list of supported devices.  Returns the matching
 * pci_device_id structure or %NULL if there is no match.
 */
static const struct pci_device_id *pci_match_device(struct pci_driver *drv,
						    struct pci_dev *dev)
{
	struct pci_dynid *dynid;
	const struct pci_device_id *found_id = NULL;

	/* When driver_override is set, only bind to the matching driver */
	if (dev->driver_override && strcmp(dev->driver_override, drv->name))
		return NULL;

	/* 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)) {
			found_id = &dynid->id;
			break;
		}
	}
	spin_unlock(&drv->dynids.lock);

	if (!found_id)
		found_id = pci_match_id(drv->id_table, dev);

	/* driver_override will always match, send a dummy id */
	if (!found_id && dev->driver_override)
		found_id = &pci_device_id_any;

	return found_id;
}

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 pci_dev *pci_dev = ddi->dev;
	struct pci_driver *pci_drv = ddi->drv;
	struct vmm_device *dev = &pci_dev->dev;
	int rc;

	/*
	 * Unbound PCI devices are always put in D0, regardless of
	 * runtime PM status.  During probe, the device is set to
	 * 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_sync(dev);
	pci_dev->driver = pci_drv;
	rc = pci_drv->probe(pci_dev, ddi->id);
	if (!rc)
		return rc;
	if (rc < 0) {
		pci_dev->driver = NULL;
		pm_runtime_put_sync(dev);
		return rc;
	}
	/*
	 * Probe function should return < 0 for failure, 0 for success
	 * Treat values > 0 as success, but warn.
	 */
	dev_warn(dev, "Driver probe function unexpectedly returned %d\n", rc);
	return 0;
}

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

#ifdef CONFIG_SMP
	int node;
	/*
	 * Execute driver initialization on node where the device is
	 * attached.  This way the driver likely allocates its local memory
	 * on the right node.
	 */
	node = dev_to_node(&dev->dev);

	/*
	 * On NUMA systems, we are likely to call a PF probe function using
	 * work_on_cpu().  If that probe calls pci_enable_sriov() (which
	 * adds the VF devices via pci_bus_add_device()), we may re-enter
	 * this function to call the VF probe function.  Calling
	 * work_on_cpu() again will cause a lockdep warning.  Since VFs are
	 * always on the same node as the PF, we can work around this by
	 * avoiding work_on_cpu() when we're already on the correct node.
	 *
	 * Preemption is enabled, so it's theoretically unsafe to use
	 * numa_node_id(), but even if we run the probe function on the
	 * wrong node, it should be functionally correct.
	 */
	if (node >= 0 && node != numa_node_id()) {
		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);
#else
	error = local_pci_probe(&ddi);
#endif

	return error;
}

/**
 * __pci_device_probe - check if a driver wants to claim a specific PCI device
 * @drv: driver to call to check if it wants the PCI device
 * @pci_dev: PCI device being probed
 *
 * returns 0 on success, else error.
 * side-effect: pci_dev->driver is set to drv when drv claims pci_dev.
 */
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)
			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_put_sync(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 vmm_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);
}

#ifdef CONFIG_PM

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

/**
 * pci_restore_standard_config - restore standard config registers of PCI device
 * @pci_dev: PCI device to handle
 */
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);
			goto Fixup;
		}
	}

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

	pci_pm_set_unknown_state(pci_dev);

Fixup:
	pci_fixup_device(pci_fixup_suspend_late, 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_has_subordinate(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_has_subordinate(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;

	/*
	 * Devices having power.ignore_children set may still be necessary for
	 * suspending their children in the next phase of device suspend.
	 */
	if (dev->power.ignore_children)
		pm_runtime_resume(dev);

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

	return error;
}


#else /* !CONFIG_PM_SLEEP */

#define pci_pm_prepare	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;
	}

	/*
	 * 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);

	pci_dev->state_saved = false;
	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);
		goto Fixup;
	}

	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);
			goto Fixup;
		}
	}

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

Fixup:
	pci_fixup_device(pci_fixup_suspend_late, pci_dev);

	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


/*
 * pcibios_pm_ops - provide arch-specific hooks when a PCI device is doing
 * a hibernate transition
 */
struct dev_pm_ops __weak pcibios_pm_ops;

static int pci_pm_freeze(struct vmm_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;
	}

	/*
	 * This used to be done in pci_pm_prepare() for all devices and some
	 * drivers may depend on it, so do it here.  Ideally, runtime-suspended
	 * devices should not be touched during freeze/thaw transitions,
	 * however.
	 */
	pm_runtime_resume(dev);

	pci_dev->state_saved = false;
	if (pm->freeze) {
		int error;

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

	if (pcibios_pm_ops.freeze)
		return pcibios_pm_ops.freeze(dev);

	return 0;
}

static int pci_pm_freeze_noirq(struct vmm_device *dev)
{
	struct pci_dev *pci_dev = to_pci_dev(dev);
	struct vmm_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);

	if (pcibios_pm_ops.freeze_noirq)
		return pcibios_pm_ops.freeze_noirq(dev);

	return 0;
}

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

	if (pcibios_pm_ops.thaw_noirq) {
		error = pcibios_pm_ops.thaw_noirq(dev);
		if (error)
			return error;
	}

	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 vmm_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 (pcibios_pm_ops.thaw) {
		error = pcibios_pm_ops.thaw(dev);
		if (error)
			return error;
	}

	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 vmm_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;
	}

	/* The reason to do that is the same as in pci_pm_suspend(). */
	pm_runtime_resume(dev);

	pci_dev->state_saved = false;
	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);

	if (pcibios_pm_ops.poweroff)
		return pcibios_pm_ops.poweroff(dev);

	return 0;
}

static int pci_pm_poweroff_noirq(struct vmm_device *dev)
{
	struct pci_dev *pci_dev = to_pci_dev(dev);
	struct vmm_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) {
		pci_fixup_device(pci_fixup_suspend_late, pci_dev);
		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_has_subordinate(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);

	pci_fixup_device(pci_fixup_suspend_late, pci_dev);

	if (pcibios_pm_ops.poweroff_noirq)
		return pcibios_pm_ops.poweroff_noirq(dev);

	return 0;
}

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

	if (pcibios_pm_ops.restore_noirq) {
		error = pcibios_pm_ops.restore_noirq(dev);
		if (error)
			return error;
	}

	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 vmm_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 (pcibios_pm_ops.restore) {
		error = pcibios_pm_ops.restore(dev);
		if (error)
			return error;
	}

	/*
	 * 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

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 pci_dev->driver is not set (unbound), the device should
	 * always remain in D0 regardless of the runtime PM status
	 */
	if (!pci_dev->driver)
		return 0;

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

	pci_dev->state_saved = false;
	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 pci_dev->driver is not set (unbound), the device should
	 * always remain in D0 regardless of the runtime PM status
	 */
	if (!pci_dev->driver)
		return 0;

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

	/*
	 * If pci_dev->driver is not set (unbound), the device should
	 * always remain in D0 regardless of the runtime PM status
	 */
	if (!pci_dev->driver)
		return 0;

	if (!pm)
		return -ENOSYS;

	if (pm->runtime_idle)
		ret = pm->runtime_idle(dev);

	return ret;
}

static const struct dev_pm_ops pci_dev_pm_ops = {
	.prepare = pci_pm_prepare,
	.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 /* !CONFIG_PM */

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

#define PCI_PM_OPS_PTR	NULL

#endif /* !CONFIG_PM */

/**
 * __pci_register_driver - register a new pci driver
 * @drv: the driver structure to register
 * @owner: owner module of drv
 * @mod_name: module name string
 *
 * Adds the driver structure to the list of registered drivers.
 * Returns a negative value on error, otherwise 0.
 * If no error occurred, the driver remains registered even if
 * no device was claimed during registration.
 */
int __pci_register_driver(struct pci_driver *drv)
{
	/* initialize common driver fields */
	memcpy(drv->driver.name, drv->name, sizeof(drv->driver.name));
	drv->driver.bus = &pci_bus_type;

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

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

/**
 * pci_unregister_driver - unregister a pci driver
 * @drv: the driver structure to unregister
 *
 * Deletes the driver structure from the list of registered PCI drivers,
 * gives it a chance to clean up by calling its remove() function for
 * each device it was responsible for, and marks those devices as
 * driverless.
 */

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

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

/**
 * pci_dev_driver - get the pci_driver of a device
 * @dev: the device to query
 *
 * Returns the appropriate pci_driver structure or %NULL if there is no
 * registered driver for the device.
 */
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;
}
EXPORT_SYMBOL(pci_dev_driver);

/**
 * pci_bus_match - Tell if a PCI device structure has a matching PCI device id structure
 * @dev: the PCI device structure to match against
 * @drv: the device driver to search for matching PCI device id structures
 *
 * Used by a driver to check whether a PCI device present in the
 * system is in its list of supported devices. Returns the matching
 * pci_device_id structure or %NULL if there is no match.
 */
static int pci_bus_match(struct vmm_device *dev, struct vmm_driver *drv)
{
	struct pci_dev *pci_dev = to_pci_dev(dev);
	struct pci_driver *pci_drv;
	const struct pci_device_id *found_id;

	if (!pci_dev->match_driver)
		return 0;

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

	return 0;
}

/**
 * pci_dev_get - increments the reference count of the pci device structure
 * @dev: the device being referenced
 *
 * Each live reference to a device should be refcounted.
 *
 * Drivers for PCI devices should normally record such references in
 * their probe() methods, when they bind to a device, and release
 * them by calling pci_dev_put(), in their disconnect() methods.
 *
 * A pointer to the device with the incremented reference counter is returned.
 */
struct pci_dev *pci_dev_get(struct pci_dev *dev)
{
	if (dev)
		get_device(&dev->dev);
	return dev;
}
EXPORT_SYMBOL(pci_dev_get);

/**
 * pci_dev_put - release a use of the pci device structure
 * @dev: device that's been disconnected
 *
 * Must be called when a user of a device is finished with it.  When the last
 * user of the device calls this function, the memory of the device is freed.
 */
void pci_dev_put(struct pci_dev *dev)
{
	if (dev)
		put_device(&dev->dev);
}
EXPORT_SYMBOL(pci_dev_put);

#if 0
static int pci_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct pci_dev *pdev;

	if (!dev)
		return -ENODEV;

	pdev = to_pci_dev(dev);

	if (add_uevent_var(env, "PCI_CLASS=%04X", pdev->class))
		return -ENOMEM;

	if (add_uevent_var(env, "PCI_ID=%04X:%04X", pdev->vendor, pdev->device))
		return -ENOMEM;

	if (add_uevent_var(env, "PCI_SUBSYS_ID=%04X:%04X", pdev->subsystem_vendor,
			   pdev->subsystem_device))
		return -ENOMEM;

	if (add_uevent_var(env, "PCI_SLOT_NAME=%s", pci_name(pdev)))
		return -ENOMEM;

	if (add_uevent_var(env, "MODALIAS=pci:v%08Xd%08Xsv%08Xsd%08Xbc%02Xsc%02Xi%02x",
			   pdev->vendor, pdev->device,
			   pdev->subsystem_vendor, pdev->subsystem_device,
			   (u8)(pdev->class >> 16), (u8)(pdev->class >> 8),
			   (u8)(pdev->class)))
		return -ENOMEM;

	return 0;
}
#endif

/*
 * PCI Bus Class
 */
static void release_pcibus_dev(struct vmm_device *dev)
{
	struct pci_bus *pci_bus = to_pci_bus(dev);

	put_device(pci_bus->bridge);
	pci_bus_remove_resources(pci_bus);
	pci_release_bus_of_node(pci_bus);
	kfree(pci_bus);
}

struct bus_type pci_bus_type = {
	.name		= "pci",
	.match		= pci_bus_match,
#if 0
	.uevent		= pci_uevent,
#endif
	.probe		= pci_device_probe,
	.remove		= pci_device_remove,
	.shutdown	= pci_device_shutdown,
#if 0
	.dev_groups	= pci_dev_groups,
	.bus_groups	= pci_bus_groups,
	.drv_groups	= pci_drv_groups,
	.pm		= PCI_PM_OPS_PTR,
#endif
};
EXPORT_SYMBOL(pci_bus_type);

struct vmm_class pcibus_class = {
	.name		= "pci_bus",
	.release	= &release_pcibus_dev,
};

static int __init pci_core_init(void)
{
	int rc = VMM_OK;

	if ((rc = bus_register(&pci_bus_type)) != VMM_OK)
		return rc;

	if ((rc = class_register(&pcibus_class)) != VMM_OK)
		goto _error;

 _error:
	bus_unregister(&pci_bus_type);

	return rc;
}

static void __exit pci_core_exit(void)
{
	bus_unregister(&pci_bus_type);
}

VMM_DECLARE_MODULE2(MODULE_NAME,
		   MODULE_DESC,
		   MODULE_AUTHOR,
		   MODULE_LICENSE,
		   MODULE_IPRIORITY,
		   MODULE_INIT,
		   MODULE_EXIT);
