/*
   * Virtio PCI driver
   *
   * This module allows virtio devices to be used over a virtual PCI device.
   * This can be used with QEMU based VMMs like KVM or Xen.
   *
   * Copyright IBM Corp. 2007
   *
   * Authors:
   *  Anthony Liguori  <aliguori@us.ibm.com>
   *
   * This work is licensed under the terms of the GNU GPL, version 2 or later.
   * See the COPYING file in the top-level directory.
   *
   */
  
  #include <linux/module.h>
  #include <linux/list.h>
  #include <linux/pci.h>

  #include <linux/slab.h>

  #include <linux/interrupt.h>
  #include <linux/virtio.h>
  #include <linux/virtio_config.h>
  #include <linux/virtio_ring.h>
  #include <linux/virtio_pci.h>
  #include <linux/highmem.h>
  #include <linux/spinlock.h>
  
  MODULE_AUTHOR("Anthony Liguori <aliguori@us.ibm.com>");
  MODULE_DESCRIPTION("virtio-pci");
  MODULE_LICENSE("GPL");
  MODULE_VERSION("1");
  
  /* Our device structure */
  struct virtio_pci_device
  {
  	struct virtio_device vdev;
  	struct pci_dev *pci_dev;
  
  	/* the IO mapping for the PCI config space */

  	void __iomem *ioaddr;

  
  	/* a list of queues so we can dispatch IRQs */
  	spinlock_t lock;
  	struct list_head virtqueues;

  
  	/* MSI-X support */
  	int msix_enabled;
  	int intx_enabled;
  	struct msix_entry *msix_entries;
  	/* Name strings for interrupts. This size should be enough,
  	 * and I'm too lazy to allocate each name separately. */
  	char (*msix_names)[256];
  	/* Number of available vectors */
  	unsigned msix_vectors;

  	/* Vectors allocated, excluding per-vq vectors if any */

  	unsigned msix_used_vectors;

  	/* Whether we have vector per vq */
  	bool per_vq_vectors;

  };
  
  /* Constants for MSI-X */
  /* Use first vector for configuration changes, second and the rest for
   * virtqueues Thus, we need at least 2 vectors for MSI. */
  enum {
  	VP_MSIX_CONFIG_VECTOR = 0,
  	VP_MSIX_VQ_VECTOR = 1,

  };
  
  struct virtio_pci_vq_info
  {
  	/* the actual virtqueue */
  	struct virtqueue *vq;
  
  	/* the number of entries in the queue */
  	int num;
  
  	/* the index of the queue */
  	int queue_index;
  
  	/* the virtual address of the ring queue */
  	void *queue;
  
  	/* the list node for the virtqueues list */
  	struct list_head node;

  
  	/* MSI-X vector (or none) */

  	unsigned msix_vector;

  };
  
  /* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
  static struct pci_device_id virtio_pci_id_table[] = {
  	{ 0x1af4, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
  	{ 0 },
  };
  
  MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);

  /* Convert a generic virtio device to our structure */
  static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
  {
  	return container_of(vdev, struct virtio_pci_device, vdev);
  }

  /* virtio config->get_features() implementation */
  static u32 vp_get_features(struct virtio_device *vdev)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  
  	/* When someone needs more than 32 feature bits, we'll need to
  	 * steal a bit to indicate that the rest are somewhere else. */
  	return ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
  }

  /* virtio config->finalize_features() implementation */
  static void vp_finalize_features(struct virtio_device *vdev)

  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	/* Give virtio_ring a chance to accept features. */
  	vring_transport_features(vdev);

  	/* We only support 32 feature bits. */
  	BUILD_BUG_ON(ARRAY_SIZE(vdev->features) != 1);
  	iowrite32(vdev->features[0], vp_dev->ioaddr+VIRTIO_PCI_GUEST_FEATURES);

  }
  
  /* virtio config->get() implementation */
  static void vp_get(struct virtio_device *vdev, unsigned offset,
  		   void *buf, unsigned len)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	void __iomem *ioaddr = vp_dev->ioaddr +
  				VIRTIO_PCI_CONFIG(vp_dev) + offset;

  	u8 *ptr = buf;
  	int i;
  
  	for (i = 0; i < len; i++)
  		ptr[i] = ioread8(ioaddr + i);
  }
  
  /* the config->set() implementation.  it's symmetric to the config->get()
   * implementation */
  static void vp_set(struct virtio_device *vdev, unsigned offset,
  		   const void *buf, unsigned len)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	void __iomem *ioaddr = vp_dev->ioaddr +
  				VIRTIO_PCI_CONFIG(vp_dev) + offset;

  	const u8 *ptr = buf;
  	int i;
  
  	for (i = 0; i < len; i++)
  		iowrite8(ptr[i], ioaddr + i);
  }
  
  /* config->{get,set}_status() implementations */
  static u8 vp_get_status(struct virtio_device *vdev)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	return ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
  }
  
  static void vp_set_status(struct virtio_device *vdev, u8 status)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	/* We should never be setting status to 0. */
  	BUG_ON(status == 0);

  	iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);

  }

  /* wait for pending irq handlers */
  static void vp_synchronize_vectors(struct virtio_device *vdev)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	int i;
  
  	if (vp_dev->intx_enabled)
  		synchronize_irq(vp_dev->pci_dev->irq);
  
  	for (i = 0; i < vp_dev->msix_vectors; ++i)
  		synchronize_irq(vp_dev->msix_entries[i].vector);
  }

  static void vp_reset(struct virtio_device *vdev)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	/* 0 status means a reset. */

  	iowrite8(0, vp_dev->ioaddr + VIRTIO_PCI_STATUS);

  	/* Flush out the status write, and flush in device writes,
  	 * including MSi-X interrupts, if any. */
  	ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
  	/* Flush pending VQ/configuration callbacks. */
  	vp_synchronize_vectors(vdev);

  }
  
  /* the notify function used when creating a virt queue */
  static void vp_notify(struct virtqueue *vq)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
  	struct virtio_pci_vq_info *info = vq->priv;
  
  	/* we write the queue's selector into the notification register to
  	 * signal the other end */
  	iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
  }

  /* Handle a configuration change: Tell driver if it wants to know. */
  static irqreturn_t vp_config_changed(int irq, void *opaque)
  {
  	struct virtio_pci_device *vp_dev = opaque;
  	struct virtio_driver *drv;
  	drv = container_of(vp_dev->vdev.dev.driver,
  			   struct virtio_driver, driver);
  
  	if (drv && drv->config_changed)
  		drv->config_changed(&vp_dev->vdev);
  	return IRQ_HANDLED;
  }
  
  /* Notify all virtqueues on an interrupt. */
  static irqreturn_t vp_vring_interrupt(int irq, void *opaque)
  {
  	struct virtio_pci_device *vp_dev = opaque;
  	struct virtio_pci_vq_info *info;
  	irqreturn_t ret = IRQ_NONE;
  	unsigned long flags;
  
  	spin_lock_irqsave(&vp_dev->lock, flags);
  	list_for_each_entry(info, &vp_dev->virtqueues, node) {
  		if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
  			ret = IRQ_HANDLED;
  	}
  	spin_unlock_irqrestore(&vp_dev->lock, flags);
  
  	return ret;
  }

  /* A small wrapper to also acknowledge the interrupt when it's handled.
   * I really need an EIO hook for the vring so I can ack the interrupt once we
   * know that we'll be handling the IRQ but before we invoke the callback since
   * the callback may notify the host which results in the host attempting to
   * raise an interrupt that we would then mask once we acknowledged the
   * interrupt. */
  static irqreturn_t vp_interrupt(int irq, void *opaque)
  {
  	struct virtio_pci_device *vp_dev = opaque;

  	u8 isr;
  
  	/* reading the ISR has the effect of also clearing it so it's very
  	 * important to save off the value. */
  	isr = ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
  
  	/* It's definitely not us if the ISR was not high */
  	if (!isr)
  		return IRQ_NONE;
  
  	/* Configuration change?  Tell driver if it wants to know. */

  	if (isr & VIRTIO_PCI_ISR_CONFIG)
  		vp_config_changed(irq, opaque);

  	return vp_vring_interrupt(irq, opaque);

  }

  static void vp_free_vectors(struct virtio_device *vdev)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	int i;
  
  	if (vp_dev->intx_enabled) {
  		free_irq(vp_dev->pci_dev->irq, vp_dev);
  		vp_dev->intx_enabled = 0;
  	}
  
  	for (i = 0; i < vp_dev->msix_used_vectors; ++i)
  		free_irq(vp_dev->msix_entries[i].vector, vp_dev);

  
  	if (vp_dev->msix_enabled) {
  		/* Disable the vector used for configuration */
  		iowrite16(VIRTIO_MSI_NO_VECTOR,
  			  vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
  		/* Flush the write out to device */
  		ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);

  		pci_disable_msix(vp_dev->pci_dev);

  		vp_dev->msix_enabled = 0;
  		vp_dev->msix_vectors = 0;

  	}

  
  	vp_dev->msix_used_vectors = 0;
  	kfree(vp_dev->msix_names);
  	vp_dev->msix_names = NULL;
  	kfree(vp_dev->msix_entries);
  	vp_dev->msix_entries = NULL;

  }

  static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
  				   bool per_vq_vectors)

  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	const char *name = dev_name(&vp_dev->vdev.dev);
  	unsigned i, v;
  	int err = -ENOMEM;

  	vp_dev->msix_entries = kmalloc(nvectors * sizeof *vp_dev->msix_entries,
  				       GFP_KERNEL);
  	if (!vp_dev->msix_entries)

  		goto error;

  	vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,
  				     GFP_KERNEL);
  	if (!vp_dev->msix_names)

  		goto error;

  
  	for (i = 0; i < nvectors; ++i)
  		vp_dev->msix_entries[i].entry = i;

  	/* pci_enable_msix returns positive if we can't get this many. */

  	err = pci_enable_msix(vp_dev->pci_dev, vp_dev->msix_entries, nvectors);
  	if (err > 0)
  		err = -ENOSPC;
  	if (err)
  		goto error;
  	vp_dev->msix_vectors = nvectors;
  	vp_dev->msix_enabled = 1;
  
  	/* Set the vector used for configuration */
  	v = vp_dev->msix_used_vectors;
  	snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
  		 "%s-config", name);
  	err = request_irq(vp_dev->msix_entries[v].vector,
  			  vp_config_changed, 0, vp_dev->msix_names[v],
  			  vp_dev);
  	if (err)
  		goto error;
  	++vp_dev->msix_used_vectors;

  	iowrite16(v, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
  	/* Verify we had enough resources to assign the vector */
  	v = ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
  	if (v == VIRTIO_MSI_NO_VECTOR) {
  		err = -EBUSY;
  		goto error;

  	}

  	if (!per_vq_vectors) {

  		/* Shared vector for all VQs */
  		v = vp_dev->msix_used_vectors;
  		snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
  			 "%s-virtqueues", name);
  		err = request_irq(vp_dev->msix_entries[v].vector,
  				  vp_vring_interrupt, 0, vp_dev->msix_names[v],
  				  vp_dev);
  		if (err)

  			goto error;

  		++vp_dev->msix_used_vectors;
  	}
  	return 0;

  error:

  	vp_free_vectors(vdev);

  	return err;
  }

  static int vp_request_intx(struct virtio_device *vdev)
  {
  	int err;
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  
  	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt,
  			  IRQF_SHARED, dev_name(&vdev->dev), vp_dev);
  	if (!err)
  		vp_dev->intx_enabled = 1;
  	return err;
  }
  
  static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
  				  void (*callback)(struct virtqueue *vq),
  				  const char *name,
  				  u16 msix_vec)

  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	struct virtio_pci_vq_info *info;
  	struct virtqueue *vq;

  	unsigned long flags, size;

  	u16 num;

  	int err;
  
  	/* Select the queue we're interested in */
  	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
  
  	/* Check if queue is either not available or already active. */
  	num = ioread16(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NUM);
  	if (!num || ioread32(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN))
  		return ERR_PTR(-ENOENT);
  
  	/* allocate and fill out our structure the represents an active
  	 * queue */
  	info = kmalloc(sizeof(struct virtio_pci_vq_info), GFP_KERNEL);
  	if (!info)
  		return ERR_PTR(-ENOMEM);
  
  	info->queue_index = index;
  	info->num = num;

  	info->msix_vector = msix_vec;

  	size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));

  	info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);

  	if (info->queue == NULL) {
  		err = -ENOMEM;
  		goto out_info;
  	}
  
  	/* activate the queue */

  	iowrite32(virt_to_phys(info->queue) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,

  		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
  
  	/* create the vring */

  	vq = vring_new_virtqueue(info->num, VIRTIO_PCI_VRING_ALIGN,

  				 vdev, info->queue, vp_notify, callback, name);

  	if (!vq) {
  		err = -ENOMEM;
  		goto out_activate_queue;
  	}
  
  	vq->priv = info;
  	info->vq = vq;

  	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
  		iowrite16(msix_vec, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
  		msix_vec = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
  		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {

  			err = -EBUSY;
  			goto out_assign;
  		}
  	}

  	if (callback) {
  		spin_lock_irqsave(&vp_dev->lock, flags);
  		list_add(&info->node, &vp_dev->virtqueues);
  		spin_unlock_irqrestore(&vp_dev->lock, flags);
  	} else {
  		INIT_LIST_HEAD(&info->node);
  	}

  
  	return vq;

  out_assign:

  	vring_del_virtqueue(vq);

  out_activate_queue:
  	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);

  	free_pages_exact(info->queue, size);

  out_info:
  	kfree(info);
  	return ERR_PTR(err);
  }

  static void vp_del_vq(struct virtqueue *vq)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
  	struct virtio_pci_vq_info *info = vq->priv;

  	unsigned long flags, size;
  
  	spin_lock_irqsave(&vp_dev->lock, flags);
  	list_del(&info->node);
  	spin_unlock_irqrestore(&vp_dev->lock, flags);

  	iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);

  	if (vp_dev->msix_enabled) {
  		iowrite16(VIRTIO_MSI_NO_VECTOR,
  			  vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
  		/* Flush the write out to device */
  		ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
  	}

  	vring_del_virtqueue(vq);
  
  	/* Select and deactivate the queue */

  	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);

  	size = PAGE_ALIGN(vring_size(info->num, VIRTIO_PCI_VRING_ALIGN));

  	free_pages_exact(info->queue, size);

  	kfree(info);
  }

  /* the config->del_vqs() implementation */

  static void vp_del_vqs(struct virtio_device *vdev)
  {

  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	struct virtqueue *vq, *n;

  	struct virtio_pci_vq_info *info;

  	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
  		info = vq->priv;

  		if (vp_dev->per_vq_vectors &&
  			info->msix_vector != VIRTIO_MSI_NO_VECTOR)

  			free_irq(vp_dev->msix_entries[info->msix_vector].vector,
  				 vq);

  		vp_del_vq(vq);

  	}
  	vp_dev->per_vq_vectors = false;

  
  	vp_free_vectors(vdev);

  }

  static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs,
  			      struct virtqueue *vqs[],
  			      vq_callback_t *callbacks[],
  			      const char *names[],

  			      bool use_msix,

  			      bool per_vq_vectors)

  {

  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	u16 msix_vec;
  	int i, err, nvectors, allocated_vectors;

  	if (!use_msix) {
  		/* Old style: one normal interrupt for change and all vqs. */
  		err = vp_request_intx(vdev);
  		if (err)
  			goto error_request;
  	} else {
  		if (per_vq_vectors) {
  			/* Best option: one for change interrupt, one per vq. */
  			nvectors = 1;
  			for (i = 0; i < nvqs; ++i)
  				if (callbacks[i])
  					++nvectors;
  		} else {
  			/* Second best: one for change, shared for all vqs. */
  			nvectors = 2;
  		}
  
  		err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors);
  		if (err)
  			goto error_request;
  	}

  	vp_dev->per_vq_vectors = per_vq_vectors;
  	allocated_vectors = vp_dev->msix_used_vectors;

  	for (i = 0; i < nvqs; ++i) {

  		if (!callbacks[i] || !vp_dev->msix_enabled)

  			msix_vec = VIRTIO_MSI_NO_VECTOR;

  		else if (vp_dev->per_vq_vectors)

  			msix_vec = allocated_vectors++;

  		else

  			msix_vec = VP_MSIX_VQ_VECTOR;
  		vqs[i] = setup_vq(vdev, i, callbacks[i], names[i], msix_vec);

  		if (IS_ERR(vqs[i])) {
  			err = PTR_ERR(vqs[i]);

  			goto error_find;

  		}

  
  		if (!vp_dev->per_vq_vectors || msix_vec == VIRTIO_MSI_NO_VECTOR)
  			continue;

  		/* allocate per-vq irq if available and necessary */

  		snprintf(vp_dev->msix_names[msix_vec],
  			 sizeof *vp_dev->msix_names,
  			 "%s-%s",
  			 dev_name(&vp_dev->vdev.dev), names[i]);
  		err = request_irq(vp_dev->msix_entries[msix_vec].vector,
  				  vring_interrupt, 0,
  				  vp_dev->msix_names[msix_vec],
  				  vqs[i]);
  		if (err) {
  			vp_del_vq(vqs[i]);
  			goto error_find;

  		}

  	}
  	return 0;

  error_find:

  	vp_del_vqs(vdev);

  
  error_request:

  	return err;
  }
  
  /* the config->find_vqs() implementation */
  static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
  		       struct virtqueue *vqs[],
  		       vq_callback_t *callbacks[],
  		       const char *names[])
  {

  	int err;

  	/* Try MSI-X with one vector per queue. */
  	err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names, true, true);

  	if (!err)
  		return 0;

  	/* Fallback: MSI-X with one vector for config, one shared for queues. */

  	err = vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,

  				 true, false);

  	if (!err)
  		return 0;
  	/* Finally fall back to regular interrupts. */

  	return vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
  				  false, false);

  }

  static struct virtio_config_ops virtio_pci_config_ops = {

  	.get		= vp_get,
  	.set		= vp_set,
  	.get_status	= vp_get_status,
  	.set_status	= vp_set_status,
  	.reset		= vp_reset,

  	.find_vqs	= vp_find_vqs,
  	.del_vqs	= vp_del_vqs,

  	.get_features	= vp_get_features,

  	.finalize_features = vp_finalize_features,

  };

  static void virtio_pci_release_dev(struct device *_d)
  {

  	/*
  	 * No need for a release method as we allocate/free
  	 * all devices together with the pci devices.
  	 * Provide an empty one to avoid getting a warning from core.
  	 */

  }

  /* the PCI probing function */
  static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
  				      const struct pci_device_id *id)
  {
  	struct virtio_pci_device *vp_dev;
  	int err;
  
  	/* We only own devices >= 0x1000 and <= 0x103f: leave the rest. */
  	if (pci_dev->device < 0x1000 || pci_dev->device > 0x103f)
  		return -ENODEV;

  	if (pci_dev->revision != VIRTIO_PCI_ABI_VERSION) {
  		printk(KERN_ERR "virtio_pci: expected ABI version %d, got %d
  ",
  		       VIRTIO_PCI_ABI_VERSION, pci_dev->revision);
  		return -ENODEV;
  	}

  	/* allocate our structure and fill it out */
  	vp_dev = kzalloc(sizeof(struct virtio_pci_device), GFP_KERNEL);
  	if (vp_dev == NULL)
  		return -ENOMEM;

  	vp_dev->vdev.dev.parent = &pci_dev->dev;

  	vp_dev->vdev.dev.release = virtio_pci_release_dev;

  	vp_dev->vdev.config = &virtio_pci_config_ops;
  	vp_dev->pci_dev = pci_dev;
  	INIT_LIST_HEAD(&vp_dev->virtqueues);
  	spin_lock_init(&vp_dev->lock);

  	/* Disable MSI/MSIX to bring device to a known good state. */
  	pci_msi_off(pci_dev);

  	/* enable the device */
  	err = pci_enable_device(pci_dev);
  	if (err)
  		goto out;
  
  	err = pci_request_regions(pci_dev, "virtio-pci");
  	if (err)
  		goto out_enable_device;
  
  	vp_dev->ioaddr = pci_iomap(pci_dev, 0, 0);
  	if (vp_dev->ioaddr == NULL)
  		goto out_req_regions;
  
  	pci_set_drvdata(pci_dev, vp_dev);

  	pci_set_master(pci_dev);

  
  	/* we use the subsystem vendor/device id as the virtio vendor/device
  	 * id.  this allows us to use the same PCI vendor/device id for all
  	 * virtio devices and to identify the particular virtio driver by

  	 * the subsystem ids */

  	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
  	vp_dev->vdev.id.device = pci_dev->subsystem_device;

  	/* finally register the virtio device */
  	err = register_virtio_device(&vp_dev->vdev);
  	if (err)

  		goto out_set_drvdata;

  
  	return 0;

  out_set_drvdata:
  	pci_set_drvdata(pci_dev, NULL);
  	pci_iounmap(pci_dev, vp_dev->ioaddr);
  out_req_regions:
  	pci_release_regions(pci_dev);
  out_enable_device:
  	pci_disable_device(pci_dev);
  out:
  	kfree(vp_dev);
  	return err;
  }
  
  static void __devexit virtio_pci_remove(struct pci_dev *pci_dev)
  {
  	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);

  	unregister_virtio_device(&vp_dev->vdev);

  
  	vp_del_vqs(&vp_dev->vdev);
  	pci_set_drvdata(pci_dev, NULL);
  	pci_iounmap(pci_dev, vp_dev->ioaddr);
  	pci_release_regions(pci_dev);
  	pci_disable_device(pci_dev);

  	kfree(vp_dev);

  }
  
  #ifdef CONFIG_PM
  static int virtio_pci_suspend(struct pci_dev *pci_dev, pm_message_t state)
  {
  	pci_save_state(pci_dev);
  	pci_set_power_state(pci_dev, PCI_D3hot);
  	return 0;
  }
  
  static int virtio_pci_resume(struct pci_dev *pci_dev)
  {
  	pci_restore_state(pci_dev);
  	pci_set_power_state(pci_dev, PCI_D0);
  	return 0;
  }
  #endif
  
  static struct pci_driver virtio_pci_driver = {
  	.name		= "virtio-pci",
  	.id_table	= virtio_pci_id_table,
  	.probe		= virtio_pci_probe,

  	.remove		= __devexit_p(virtio_pci_remove),

  #ifdef CONFIG_PM
  	.suspend	= virtio_pci_suspend,
  	.resume		= virtio_pci_resume,
  #endif
  };
  
  static int __init virtio_pci_init(void)
  {

  	return pci_register_driver(&virtio_pci_driver);

  }
  
  module_init(virtio_pci_init);
  
  static void __exit virtio_pci_exit(void)
  {

  	pci_unregister_driver(&virtio_pci_driver);
  }
  
  module_exit(virtio_pci_exit);