include/linux/virtio_config.h

   1 #ifndef _LINUX_VIRTIO_CONFIG_H
   2 #define _LINUX_VIRTIO_CONFIG_H
   3 /* Virtio devices use a standardized configuration space to define their
   4  * features and pass configuration information, but each implementation can
   5  * store and access that space differently. */
   6 #include <linux/types.h>
   7
   8 /* Status byte for guest to report progress, and synchronize features. */
   9 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
  10 #define VIRTIO_CONFIG_S_ACKNOWLEDGE     1
  11 /* We have found a driver for the device. */
  12 #define VIRTIO_CONFIG_S_DRIVER          2
  13 /* Driver has used its parts of the config, and is happy */
  14 #define VIRTIO_CONFIG_S_DRIVER_OK       4
  15 /* We've given up on this device. */
  16 #define VIRTIO_CONFIG_S_FAILED          0x80
  17
  18 #ifdef __KERNEL__
  19 struct virtio_device;
  20
  21 /**
  22  * virtio_config_ops - operations for configuring a virtio device
  23  * @feature: search for a feature in this config
  24  *      vdev: the virtio_device
  25  *      bit: the feature bit
  26  *      Returns true if the feature is supported.  Acknowledges the feature
  27  *      so the host can see it.
  28  * @get: read the value of a configuration field
  29  *      vdev: the virtio_device
  30  *      offset: the offset of the configuration field
  31  *      buf: the buffer to write the field value into.
  32  *      len: the length of the buffer
  33  *      Note that contents are conventionally little-endian.
  34  * @set: write the value of a configuration field
  35  *      vdev: the virtio_device
  36  *      offset: the offset of the configuration field
  37  *      buf: the buffer to read the field value from.
  38  *      len: the length of the buffer
  39  *      Note that contents are conventionally little-endian.
  40  * @get_status: read the status byte
  41  *      vdev: the virtio_device
  42  *      Returns the status byte
  43  * @set_status: write the status byte
  44  *      vdev: the virtio_device
  45  *      status: the new status byte
  46  * @reset: reset the device
  47  *      vdev: the virtio device
  48  *      After this, status and feature negotiation must be done again
  49  * @find_vq: find a virtqueue and instantiate it.
  50  *      vdev: the virtio_device
  51  *      index: the 0-based virtqueue number in case there's more than one.
  52  *      callback: the virqtueue callback
  53  *      Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
  54  * @del_vq: free a virtqueue found by find_vq().
  55  */
  56 struct virtio_config_ops
  57 {
  58         bool (*feature)(struct virtio_device *vdev, unsigned bit);
  59         void (*get)(struct virtio_device *vdev, unsigned offset,
  60                     void *buf, unsigned len);
  61         void (*set)(struct virtio_device *vdev, unsigned offset,
  62                     const void *buf, unsigned len);
  63         u8 (*get_status)(struct virtio_device *vdev);
  64         void (*set_status)(struct virtio_device *vdev, u8 status);
  65         void (*reset)(struct virtio_device *vdev);
  66         struct virtqueue *(*find_vq)(struct virtio_device *vdev,
  67                                      unsigned index,
  68                                      void (*callback)(struct virtqueue *));
  69         void (*del_vq)(struct virtqueue *vq);
  70 };
  71
  72 /**
  73  * virtio_config_val - look for a feature and get a single virtio config.
  74  * @vdev: the virtio device
  75  * @fbit: the feature bit
  76  * @offset: the type to search for.
  77  * @val: a pointer to the value to fill in.
  78  *
  79  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
  80  * the value is endian-corrected and returned in v. */
  81 #define virtio_config_val(vdev, fbit, offset, v) ({                     \
  82         int _err;                                                       \
  83         if ((vdev)->config->feature((vdev), (fbit))) {                  \
  84                 __virtio_config_val((vdev), (offset), (v));             \
  85                 _err = 0;                                               \
  86         } else                                                          \
  87                 _err = -ENOENT;                                         \
  88         _err;                                                           \
  89 })
  90
  91 /**
  92  * __virtio_config_val - get a single virtio config without feature check.
  93  * @vdev: the virtio device
  94  * @offset: the type to search for.
  95  * @val: a pointer to the value to fill in.
  96  *
  97  * The value is endian-corrected and returned in v. */
  98 #define __virtio_config_val(vdev, offset, v) do {                       \
  99         BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2             \
 100                      && sizeof(*(v)) != 4 && sizeof(*(v)) != 8);        \
 101         (vdev)->config->get((vdev), (offset), (v), sizeof(*(v)));       \
 102         switch (sizeof(*(v))) {                                         \
 103         case 2: le16_to_cpus((__u16 *) v); break;                       \
 104         case 4: le32_to_cpus((__u32 *) v); break;                       \
 105         case 8: le64_to_cpus((__u64 *) v); break;                       \
 106         }                                                               \
 107 } while(0)
 108 #endif /* __KERNEL__ */
 109 #endif /* _LINUX_VIRTIO_CONFIG_H */