/*
   * 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 header is BSD licensed so anyone can use the definitions to implement
   * compatible drivers/servers.

   */
  
  #ifndef _LINUX_VIRTIO_PCI_H
  #define _LINUX_VIRTIO_PCI_H
  
  #include <linux/virtio_config.h>
  
  /* A 32-bit r/o bitmask of the features supported by the host */
  #define VIRTIO_PCI_HOST_FEATURES	0
  
  /* A 32-bit r/w bitmask of features activated by the guest */
  #define VIRTIO_PCI_GUEST_FEATURES	4
  
  /* A 32-bit r/w PFN for the currently selected queue */
  #define VIRTIO_PCI_QUEUE_PFN		8
  
  /* A 16-bit r/o queue size for the currently selected queue */
  #define VIRTIO_PCI_QUEUE_NUM		12
  
  /* A 16-bit r/w queue selector */
  #define VIRTIO_PCI_QUEUE_SEL		14
  
  /* A 16-bit r/w queue notifier */
  #define VIRTIO_PCI_QUEUE_NOTIFY		16
  
  /* An 8-bit device status register.  */
  #define VIRTIO_PCI_STATUS		18
  
  /* An 8-bit r/o interrupt status register.  Reading the value will return the
   * current contents of the ISR and will also clear it.  This is effectively
   * a read-and-acknowledge. */
  #define VIRTIO_PCI_ISR			19
  
  /* The bit of the ISR which indicates a device configuration change. */
  #define VIRTIO_PCI_ISR_CONFIG		0x2

  /* MSI-X registers: only enabled if MSI-X is enabled. */
  /* A 16-bit vector for configuration changes. */
  #define VIRTIO_MSI_CONFIG_VECTOR        20
  /* A 16-bit vector for selected queue notifications. */
  #define VIRTIO_MSI_QUEUE_VECTOR         22
  /* Vector value used to disable MSI for queue */
  #define VIRTIO_MSI_NO_VECTOR            0xffff

  /* The remaining space is defined by each driver as the per-driver
   * configuration space */

  #define VIRTIO_PCI_CONFIG(dev)		((dev)->msix_enabled ? 24 : 20)

  /* Virtio ABI version, this must match exactly */
  #define VIRTIO_PCI_ABI_VERSION		0

  
  /* How many bits to shift physical queue address written to QUEUE_PFN.
   * 12 is historical, and due to x86 page size. */
  #define VIRTIO_PCI_QUEUE_ADDR_SHIFT	12

  
  /* The alignment to use between consumer and producer parts of vring.
   * x86 pagesize again. */
  #define VIRTIO_PCI_VRING_ALIGN		4096

  #endif