/*
   * drivers/pci/iov.c
   *
   * Copyright (C) 2009 Intel Corporation, Yu Zhao <yu.zhao@intel.com>
   *
   * PCI Express I/O Virtualization (IOV) support.
   *   Single Root IOV 1.0

   *   Address Translation Service 1.0

   */
  
  #include <linux/pci.h>

  #include <linux/slab.h>

  #include <linux/mutex.h>

  #include <linux/export.h>

  #include <linux/string.h>
  #include <linux/delay.h>

  #include <linux/pci-ats.h>

  #include "pci.h"

  #define VIRTFN_ID_LEN	16

  static inline u8 virtfn_bus(struct pci_dev *dev, int id)
  {
  	return dev->bus->number + ((dev->devfn + dev->sriov->offset +
  				    dev->sriov->stride * id) >> 8);
  }
  
  static inline u8 virtfn_devfn(struct pci_dev *dev, int id)
  {
  	return (dev->devfn + dev->sriov->offset +
  		dev->sriov->stride * id) & 0xff;
  }

  static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
  {
  	int rc;
  	struct pci_bus *child;
  
  	if (bus->number == busnr)
  		return bus;
  
  	child = pci_find_bus(pci_domain_nr(bus), busnr);
  	if (child)
  		return child;
  
  	child = pci_add_new_bus(bus, NULL, busnr);
  	if (!child)
  		return NULL;
  
  	child->subordinate = busnr;
  	child->dev.parent = bus->bridge;
  	rc = pci_bus_add_child(child);
  	if (rc) {
  		pci_remove_bus(child);
  		return NULL;
  	}
  
  	return child;
  }
  
  static void virtfn_remove_bus(struct pci_bus *bus, int busnr)
  {
  	struct pci_bus *child;
  
  	if (bus->number == busnr)
  		return;
  
  	child = pci_find_bus(pci_domain_nr(bus), busnr);
  	BUG_ON(!child);
  
  	if (list_empty(&child->devices))
  		pci_remove_bus(child);
  }
  
  static int virtfn_add(struct pci_dev *dev, int id, int reset)
  {
  	int i;
  	int rc;
  	u64 size;
  	char buf[VIRTFN_ID_LEN];
  	struct pci_dev *virtfn;
  	struct resource *res;
  	struct pci_sriov *iov = dev->sriov;
  
  	virtfn = alloc_pci_dev();
  	if (!virtfn)
  		return -ENOMEM;
  
  	mutex_lock(&iov->dev->sriov->lock);
  	virtfn->bus = virtfn_add_bus(dev->bus, virtfn_bus(dev, id));
  	if (!virtfn->bus) {
  		kfree(virtfn);
  		mutex_unlock(&iov->dev->sriov->lock);
  		return -ENOMEM;
  	}
  	virtfn->devfn = virtfn_devfn(dev, id);
  	virtfn->vendor = dev->vendor;
  	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_DID, &virtfn->device);
  	pci_setup_device(virtfn);
  	virtfn->dev.parent = dev->dev.parent;
  
  	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
  		res = dev->resource + PCI_IOV_RESOURCES + i;
  		if (!res->parent)
  			continue;
  		virtfn->resource[i].name = pci_name(virtfn);
  		virtfn->resource[i].flags = res->flags;
  		size = resource_size(res);
  		do_div(size, iov->total);
  		virtfn->resource[i].start = res->start + size * id;
  		virtfn->resource[i].end = virtfn->resource[i].start + size - 1;
  		rc = request_resource(res, &virtfn->resource[i]);
  		BUG_ON(rc);
  	}
  
  	if (reset)

  		__pci_reset_function(virtfn);

  
  	pci_device_add(virtfn, virtfn->bus);
  	mutex_unlock(&iov->dev->sriov->lock);
  
  	virtfn->physfn = pci_dev_get(dev);
  	virtfn->is_virtfn = 1;
  
  	rc = pci_bus_add_device(virtfn);
  	if (rc)
  		goto failed1;
  	sprintf(buf, "virtfn%u", id);
  	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
  	if (rc)
  		goto failed1;
  	rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
  	if (rc)
  		goto failed2;
  
  	kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
  
  	return 0;
  
  failed2:
  	sysfs_remove_link(&dev->dev.kobj, buf);
  failed1:
  	pci_dev_put(dev);
  	mutex_lock(&iov->dev->sriov->lock);
  	pci_remove_bus_device(virtfn);
  	virtfn_remove_bus(dev->bus, virtfn_bus(dev, id));
  	mutex_unlock(&iov->dev->sriov->lock);
  
  	return rc;
  }
  
  static void virtfn_remove(struct pci_dev *dev, int id, int reset)
  {
  	char buf[VIRTFN_ID_LEN];
  	struct pci_bus *bus;
  	struct pci_dev *virtfn;
  	struct pci_sriov *iov = dev->sriov;
  
  	bus = pci_find_bus(pci_domain_nr(dev->bus), virtfn_bus(dev, id));
  	if (!bus)
  		return;
  
  	virtfn = pci_get_slot(bus, virtfn_devfn(dev, id));
  	if (!virtfn)
  		return;
  
  	pci_dev_put(virtfn);
  
  	if (reset) {
  		device_release_driver(&virtfn->dev);

  		__pci_reset_function(virtfn);

  	}
  
  	sprintf(buf, "virtfn%u", id);
  	sysfs_remove_link(&dev->dev.kobj, buf);
  	sysfs_remove_link(&virtfn->dev.kobj, "physfn");
  
  	mutex_lock(&iov->dev->sriov->lock);
  	pci_remove_bus_device(virtfn);
  	virtfn_remove_bus(dev->bus, virtfn_bus(dev, id));
  	mutex_unlock(&iov->dev->sriov->lock);
  
  	pci_dev_put(dev);
  }

  static int sriov_migration(struct pci_dev *dev)
  {
  	u16 status;
  	struct pci_sriov *iov = dev->sriov;
  
  	if (!iov->nr_virtfn)
  		return 0;
  
  	if (!(iov->cap & PCI_SRIOV_CAP_VFM))
  		return 0;
  
  	pci_read_config_word(dev, iov->pos + PCI_SRIOV_STATUS, &status);
  	if (!(status & PCI_SRIOV_STATUS_VFM))
  		return 0;
  
  	schedule_work(&iov->mtask);
  
  	return 1;
  }
  
  static void sriov_migration_task(struct work_struct *work)
  {
  	int i;
  	u8 state;
  	u16 status;
  	struct pci_sriov *iov = container_of(work, struct pci_sriov, mtask);
  
  	for (i = iov->initial; i < iov->nr_virtfn; i++) {
  		state = readb(iov->mstate + i);
  		if (state == PCI_SRIOV_VFM_MI) {
  			writeb(PCI_SRIOV_VFM_AV, iov->mstate + i);
  			state = readb(iov->mstate + i);
  			if (state == PCI_SRIOV_VFM_AV)
  				virtfn_add(iov->self, i, 1);
  		} else if (state == PCI_SRIOV_VFM_MO) {
  			virtfn_remove(iov->self, i, 1);
  			writeb(PCI_SRIOV_VFM_UA, iov->mstate + i);
  			state = readb(iov->mstate + i);
  			if (state == PCI_SRIOV_VFM_AV)
  				virtfn_add(iov->self, i, 0);
  		}
  	}
  
  	pci_read_config_word(iov->self, iov->pos + PCI_SRIOV_STATUS, &status);
  	status &= ~PCI_SRIOV_STATUS_VFM;
  	pci_write_config_word(iov->self, iov->pos + PCI_SRIOV_STATUS, status);
  }
  
  static int sriov_enable_migration(struct pci_dev *dev, int nr_virtfn)
  {
  	int bir;
  	u32 table;
  	resource_size_t pa;
  	struct pci_sriov *iov = dev->sriov;
  
  	if (nr_virtfn <= iov->initial)
  		return 0;
  
  	pci_read_config_dword(dev, iov->pos + PCI_SRIOV_VFM, &table);
  	bir = PCI_SRIOV_VFM_BIR(table);
  	if (bir > PCI_STD_RESOURCE_END)
  		return -EIO;
  
  	table = PCI_SRIOV_VFM_OFFSET(table);
  	if (table + nr_virtfn > pci_resource_len(dev, bir))
  		return -EIO;
  
  	pa = pci_resource_start(dev, bir) + table;
  	iov->mstate = ioremap(pa, nr_virtfn);
  	if (!iov->mstate)
  		return -ENOMEM;
  
  	INIT_WORK(&iov->mtask, sriov_migration_task);
  
  	iov->ctrl |= PCI_SRIOV_CTRL_VFM | PCI_SRIOV_CTRL_INTR;
  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
  
  	return 0;
  }
  
  static void sriov_disable_migration(struct pci_dev *dev)
  {
  	struct pci_sriov *iov = dev->sriov;
  
  	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFM | PCI_SRIOV_CTRL_INTR);
  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
  
  	cancel_work_sync(&iov->mtask);
  	iounmap(iov->mstate);
  }

  static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
  {
  	int rc;
  	int i, j;
  	int nres;
  	u16 offset, stride, initial;
  	struct resource *res;
  	struct pci_dev *pdev;
  	struct pci_sriov *iov = dev->sriov;

  	int bars = 0;

  
  	if (!nr_virtfn)
  		return 0;
  
  	if (iov->nr_virtfn)
  		return -EINVAL;
  
  	pci_read_config_word(dev, iov->pos + PCI_SRIOV_INITIAL_VF, &initial);
  	if (initial > iov->total ||
  	    (!(iov->cap & PCI_SRIOV_CAP_VFM) && (initial != iov->total)))
  		return -EIO;
  
  	if (nr_virtfn < 0 || nr_virtfn > iov->total ||
  	    (!(iov->cap & PCI_SRIOV_CAP_VFM) && (nr_virtfn > initial)))
  		return -EINVAL;
  
  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, nr_virtfn);
  	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_OFFSET, &offset);
  	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_STRIDE, &stride);
  	if (!offset || (nr_virtfn > 1 && !stride))
  		return -EIO;
  
  	nres = 0;
  	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {

  		bars |= (1 << (i + PCI_IOV_RESOURCES));

  		res = dev->resource + PCI_IOV_RESOURCES + i;
  		if (res->parent)
  			nres++;
  	}
  	if (nres != iov->nres) {
  		dev_err(&dev->dev, "not enough MMIO resources for SR-IOV
  ");
  		return -ENOMEM;
  	}
  
  	iov->offset = offset;
  	iov->stride = stride;
  
  	if (virtfn_bus(dev, nr_virtfn - 1) > dev->bus->subordinate) {
  		dev_err(&dev->dev, "SR-IOV: bus number out of range
  ");
  		return -ENOMEM;
  	}

  	if (pci_enable_resources(dev, bars)) {
  		dev_err(&dev->dev, "SR-IOV: IOV BARS not allocated
  ");
  		return -ENOMEM;
  	}

  	if (iov->link != dev->devfn) {
  		pdev = pci_get_slot(dev->bus, iov->link);
  		if (!pdev)
  			return -ENODEV;
  
  		pci_dev_put(pdev);
  
  		if (!pdev->is_physfn)
  			return -ENODEV;
  
  		rc = sysfs_create_link(&dev->dev.kobj,
  					&pdev->dev.kobj, "dep_link");
  		if (rc)
  			return rc;
  	}

  	pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);

  	iov->ctrl |= PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE;

  	pci_cfg_access_lock(dev);

  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
  	msleep(100);

  	pci_cfg_access_unlock(dev);

  
  	iov->initial = initial;
  	if (nr_virtfn < initial)
  		initial = nr_virtfn;
  
  	for (i = 0; i < initial; i++) {
  		rc = virtfn_add(dev, i, 0);
  		if (rc)
  			goto failed;
  	}

  	if (iov->cap & PCI_SRIOV_CAP_VFM) {
  		rc = sriov_enable_migration(dev, nr_virtfn);
  		if (rc)
  			goto failed;
  	}

  	kobject_uevent(&dev->dev.kobj, KOBJ_CHANGE);
  	iov->nr_virtfn = nr_virtfn;
  
  	return 0;
  
  failed:
  	for (j = 0; j < i; j++)
  		virtfn_remove(dev, j, 0);
  
  	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);

  	pci_cfg_access_lock(dev);

  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
  	ssleep(1);

  	pci_cfg_access_unlock(dev);

  
  	if (iov->link != dev->devfn)
  		sysfs_remove_link(&dev->dev.kobj, "dep_link");
  
  	return rc;
  }
  
  static void sriov_disable(struct pci_dev *dev)
  {
  	int i;
  	struct pci_sriov *iov = dev->sriov;
  
  	if (!iov->nr_virtfn)
  		return;

  	if (iov->cap & PCI_SRIOV_CAP_VFM)
  		sriov_disable_migration(dev);

  	for (i = 0; i < iov->nr_virtfn; i++)
  		virtfn_remove(dev, i, 0);
  
  	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);

  	pci_cfg_access_lock(dev);

  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
  	ssleep(1);

  	pci_cfg_access_unlock(dev);

  
  	if (iov->link != dev->devfn)
  		sysfs_remove_link(&dev->dev.kobj, "dep_link");
  
  	iov->nr_virtfn = 0;
  }

  static int sriov_init(struct pci_dev *dev, int pos)
  {
  	int i;
  	int rc;
  	int nres;
  	u32 pgsz;
  	u16 ctrl, total, offset, stride;
  	struct pci_sriov *iov;
  	struct resource *res;
  	struct pci_dev *pdev;
  
  	if (dev->pcie_type != PCI_EXP_TYPE_RC_END &&
  	    dev->pcie_type != PCI_EXP_TYPE_ENDPOINT)
  		return -ENODEV;
  
  	pci_read_config_word(dev, pos + PCI_SRIOV_CTRL, &ctrl);
  	if (ctrl & PCI_SRIOV_CTRL_VFE) {
  		pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, 0);
  		ssleep(1);
  	}
  
  	pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total);
  	if (!total)
  		return 0;
  
  	ctrl = 0;
  	list_for_each_entry(pdev, &dev->bus->devices, bus_list)
  		if (pdev->is_physfn)
  			goto found;
  
  	pdev = NULL;
  	if (pci_ari_enabled(dev->bus))
  		ctrl |= PCI_SRIOV_CTRL_ARI;
  
  found:
  	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);

  	pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
  	pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
  	if (!offset || (total > 1 && !stride))
  		return -EIO;
  
  	pci_read_config_dword(dev, pos + PCI_SRIOV_SUP_PGSIZE, &pgsz);
  	i = PAGE_SHIFT > 12 ? PAGE_SHIFT - 12 : 0;
  	pgsz &= ~((1 << i) - 1);
  	if (!pgsz)
  		return -EIO;
  
  	pgsz &= ~(pgsz - 1);

  
  	nres = 0;
  	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
  		res = dev->resource + PCI_IOV_RESOURCES + i;
  		i += __pci_read_base(dev, pci_bar_unknown, res,
  				     pos + PCI_SRIOV_BAR + i * 4);
  		if (!res->flags)
  			continue;
  		if (resource_size(res) & (PAGE_SIZE - 1)) {
  			rc = -EIO;
  			goto failed;
  		}
  		res->end = res->start + resource_size(res) * total - 1;
  		nres++;
  	}
  
  	iov = kzalloc(sizeof(*iov), GFP_KERNEL);
  	if (!iov) {
  		rc = -ENOMEM;
  		goto failed;
  	}
  
  	iov->pos = pos;
  	iov->nres = nres;
  	iov->ctrl = ctrl;
  	iov->total = total;
  	iov->offset = offset;
  	iov->stride = stride;
  	iov->pgsz = pgsz;
  	iov->self = dev;
  	pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
  	pci_read_config_byte(dev, pos + PCI_SRIOV_FUNC_LINK, &iov->link);

  	if (dev->pcie_type == PCI_EXP_TYPE_RC_END)
  		iov->link = PCI_DEVFN(PCI_SLOT(dev->devfn), iov->link);

  
  	if (pdev)
  		iov->dev = pci_dev_get(pdev);

  	else

  		iov->dev = dev;

  
  	mutex_init(&iov->lock);

  
  	dev->sriov = iov;
  	dev->is_physfn = 1;
  
  	return 0;
  
  failed:
  	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
  		res = dev->resource + PCI_IOV_RESOURCES + i;
  		res->flags = 0;
  	}
  
  	return rc;
  }
  
  static void sriov_release(struct pci_dev *dev)
  {

  	BUG_ON(dev->sriov->nr_virtfn);

  	if (dev != dev->sriov->dev)

  		pci_dev_put(dev->sriov->dev);

  	mutex_destroy(&dev->sriov->lock);

  	kfree(dev->sriov);
  	dev->sriov = NULL;
  }

  static void sriov_restore_state(struct pci_dev *dev)
  {
  	int i;
  	u16 ctrl;
  	struct pci_sriov *iov = dev->sriov;
  
  	pci_read_config_word(dev, iov->pos + PCI_SRIOV_CTRL, &ctrl);
  	if (ctrl & PCI_SRIOV_CTRL_VFE)
  		return;
  
  	for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++)
  		pci_update_resource(dev, i);
  
  	pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);

  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, iov->nr_virtfn);

  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
  	if (iov->ctrl & PCI_SRIOV_CTRL_VFE)
  		msleep(100);
  }

  /**
   * pci_iov_init - initialize the IOV capability
   * @dev: the PCI device
   *
   * Returns 0 on success, or negative on failure.
   */
  int pci_iov_init(struct pci_dev *dev)
  {
  	int pos;

  	if (!pci_is_pcie(dev))

  		return -ENODEV;
  
  	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_SRIOV);
  	if (pos)
  		return sriov_init(dev, pos);
  
  	return -ENODEV;
  }
  
  /**
   * pci_iov_release - release resources used by the IOV capability
   * @dev: the PCI device
   */
  void pci_iov_release(struct pci_dev *dev)
  {
  	if (dev->is_physfn)
  		sriov_release(dev);
  }
  
  /**
   * pci_iov_resource_bar - get position of the SR-IOV BAR
   * @dev: the PCI device
   * @resno: the resource number
   * @type: the BAR type to be filled in
   *
   * Returns position of the BAR encapsulated in the SR-IOV capability.
   */
  int pci_iov_resource_bar(struct pci_dev *dev, int resno,
  			 enum pci_bar_type *type)
  {
  	if (resno < PCI_IOV_RESOURCES || resno > PCI_IOV_RESOURCE_END)
  		return 0;
  
  	BUG_ON(!dev->is_physfn);
  
  	*type = pci_bar_unknown;
  
  	return dev->sriov->pos + PCI_SRIOV_BAR +
  		4 * (resno - PCI_IOV_RESOURCES);
  }

  
  /**

   * pci_sriov_resource_alignment - get resource alignment for VF BAR
   * @dev: the PCI device
   * @resno: the resource number
   *
   * Returns the alignment of the VF BAR found in the SR-IOV capability.
   * This is not the same as the resource size which is defined as
   * the VF BAR size multiplied by the number of VFs.  The alignment
   * is just the VF BAR size.
   */

  resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno)

  {
  	struct resource tmp;
  	enum pci_bar_type type;
  	int reg = pci_iov_resource_bar(dev, resno, &type);
  	
  	if (!reg)
  		return 0;
  
  	 __pci_read_base(dev, type, &tmp, reg);
  	return resource_alignment(&tmp);
  }
  
  /**

   * pci_restore_iov_state - restore the state of the IOV capability
   * @dev: the PCI device
   */
  void pci_restore_iov_state(struct pci_dev *dev)
  {
  	if (dev->is_physfn)
  		sriov_restore_state(dev);
  }

  
  /**
   * pci_iov_bus_range - find bus range used by Virtual Function
   * @bus: the PCI bus
   *
   * Returns max number of buses (exclude current one) used by Virtual
   * Functions.
   */
  int pci_iov_bus_range(struct pci_bus *bus)
  {
  	int max = 0;
  	u8 busnr;
  	struct pci_dev *dev;
  
  	list_for_each_entry(dev, &bus->devices, bus_list) {
  		if (!dev->is_physfn)
  			continue;
  		busnr = virtfn_bus(dev, dev->sriov->total - 1);
  		if (busnr > max)
  			max = busnr;
  	}
  
  	return max ? max - bus->number : 0;
  }

  
  /**
   * pci_enable_sriov - enable the SR-IOV capability
   * @dev: the PCI device

   * @nr_virtfn: number of virtual functions to enable

   *
   * Returns 0 on success, or negative on failure.
   */
  int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
  {
  	might_sleep();
  
  	if (!dev->is_physfn)
  		return -ENODEV;
  
  	return sriov_enable(dev, nr_virtfn);
  }
  EXPORT_SYMBOL_GPL(pci_enable_sriov);
  
  /**
   * pci_disable_sriov - disable the SR-IOV capability
   * @dev: the PCI device
   */
  void pci_disable_sriov(struct pci_dev *dev)
  {
  	might_sleep();
  
  	if (!dev->is_physfn)
  		return;
  
  	sriov_disable(dev);
  }
  EXPORT_SYMBOL_GPL(pci_disable_sriov);

  
  /**
   * pci_sriov_migration - notify SR-IOV core of Virtual Function Migration
   * @dev: the PCI device
   *
   * Returns IRQ_HANDLED if the IRQ is handled, or IRQ_NONE if not.
   *
   * Physical Function driver is responsible to register IRQ handler using
   * VF Migration Interrupt Message Number, and call this function when the
   * interrupt is generated by the hardware.
   */
  irqreturn_t pci_sriov_migration(struct pci_dev *dev)
  {
  	if (!dev->is_physfn)
  		return IRQ_NONE;
  
  	return sriov_migration(dev) ? IRQ_HANDLED : IRQ_NONE;
  }
  EXPORT_SYMBOL_GPL(pci_sriov_migration);

  /**
   * pci_num_vf - return number of VFs associated with a PF device_release_driver
   * @dev: the PCI device
   *
   * Returns number of VFs, or 0 if SR-IOV is not enabled.
   */
  int pci_num_vf(struct pci_dev *dev)
  {
  	if (!dev || !dev->is_physfn)
  		return 0;
  	else
  		return dev->sriov->nr_virtfn;
  }
  EXPORT_SYMBOL_GPL(pci_num_vf);