include/linux/virtio_config.h

   1 #ifndef _LINUX_VIRTIO_CONFIG_H
   2 #define _LINUX_VIRTIO_CONFIG_H
   3 /* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
   4  * anyone can use the definitions to implement compatible drivers/servers. */
   5
   6 /* Virtio devices use a standardized configuration space to define their
   7  * features and pass configuration information, but each implementation can
   8  * store and access that space differently. */
   9 #include <linux/types.h>
  10
  11 /* Status byte for guest to report progress, and synchronize features. */
  12 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
  13 #define VIRTIO_CONFIG_S_ACKNOWLEDGE     1
  14 /* We have found a driver for the device. */
  15 #define VIRTIO_CONFIG_S_DRIVER          2
  16 /* Driver has used its parts of the config, and is happy */
  17 #define VIRTIO_CONFIG_S_DRIVER_OK       4
  18 /* We've given up on this device. */
  19 #define VIRTIO_CONFIG_S_FAILED          0x80
  20
  21 /* Some virtio feature bits (currently bits 28 through 31) are reserved for the
  22  * transport being used (eg. virtio_ring), the rest are per-device feature
  23  * bits. */
  24 #define VIRTIO_TRANSPORT_F_START        28
  25 #define VIRTIO_TRANSPORT_F_END          32
  26
  27 /* Do we get callbacks when the ring is completely used, even if we've
  28  * suppressed them? */
  29 #define VIRTIO_F_NOTIFY_ON_EMPTY        24
  30
  31 #ifdef __KERNEL__
  32 #include <linux/virtio.h>
  33
  34 /**
  35  * virtio_config_ops - operations for configuring a virtio device
  36  * @get: read the value of a configuration field
  37  *      vdev: the virtio_device
  38  *      offset: the offset of the configuration field
  39  *      buf: the buffer to write the field value into.
  40  *      len: the length of the buffer
  41  * @set: write the value of a configuration field
  42  *      vdev: the virtio_device
  43  *      offset: the offset of the configuration field
  44  *      buf: the buffer to read the field value from.
  45  *      len: the length of the buffer
  46  * @get_status: read the status byte
  47  *      vdev: the virtio_device
  48  *      Returns the status byte
  49  * @set_status: write the status byte
  50  *      vdev: the virtio_device
  51  *      status: the new status byte
  52  * @reset: reset the device
  53  *      vdev: the virtio device
  54  *      After this, status and feature negotiation must be done again
  55  * @find_vq: find a virtqueue and instantiate it.
  56  *      vdev: the virtio_device
  57  *      index: the 0-based virtqueue number in case there's more than one.
  58  *      callback: the virqtueue callback
  59  *      Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
  60  * @del_vq: free a virtqueue found by find_vq().
  61  * @get_features: get the array of feature bits for this device.
  62  *      vdev: the virtio_device
  63  *      Returns the first 32 feature bits (all we currently need).
  64  * @finalize_features: confirm what device features we'll be using.
  65  *      vdev: the virtio_device
  66  *      This gives the final feature bits for the device: it can change
  67  *      the dev->feature bits if it wants.
  68  */
  69 struct virtio_config_ops
  70 {
  71         void (*get)(struct virtio_device *vdev, unsigned offset,
  72                     void *buf, unsigned len);
  73         void (*set)(struct virtio_device *vdev, unsigned offset,
  74                     const void *buf, unsigned len);
  75         u8 (*get_status)(struct virtio_device *vdev);
  76         void (*set_status)(struct virtio_device *vdev, u8 status);
  77         void (*reset)(struct virtio_device *vdev);
  78         struct virtqueue *(*find_vq)(struct virtio_device *vdev,
  79                                      unsigned index,
  80                                      void (*callback)(struct virtqueue *));
  81         void (*del_vq)(struct virtqueue *vq);
  82         u32 (*get_features)(struct virtio_device *vdev);
  83         void (*finalize_features)(struct virtio_device *vdev);
  84 };
  85
  86 /* If driver didn't advertise the feature, it will never appear. */
  87 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  88                                          unsigned int fbit);
  89
  90 /**
  91  * virtio_has_feature - helper to determine if this device has this feature.
  92  * @vdev: the device
  93  * @fbit: the feature bit
  94  */
  95 static inline bool virtio_has_feature(const struct virtio_device *vdev,
  96                                       unsigned int fbit)
  97 {
  98         /* Did you forget to fix assumptions on max features? */
  99         if (__builtin_constant_p(fbit))
 100                 BUILD_BUG_ON(fbit >= 32);
 101
 102         virtio_check_driver_offered_feature(vdev, fbit);
 103         return test_bit(fbit, vdev->features);
 104 }
 105
 106 /**
 107  * virtio_config_val - look for a feature and get a virtio config entry.
 108  * @vdev: the virtio device
 109  * @fbit: the feature bit
 110  * @offset: the type to search for.
 111  * @val: a pointer to the value to fill in.
 112  *
 113  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
 114  * the config value is copied into whatever is pointed to by v. */
 115 #define virtio_config_val(vdev, fbit, offset, v) \
 116         virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
 117
 118 static inline int virtio_config_buf(struct virtio_device *vdev,
 119                                     unsigned int fbit,
 120                                     unsigned int offset,
 121                                     void *buf, unsigned len)
 122 {
 123         if (!virtio_has_feature(vdev, fbit))
 124                 return -ENOENT;
 125
 126         vdev->config->get(vdev, offset, buf, len);
 127         return 0;
 128 }
 129 #endif /* __KERNEL__ */
 130 #endif /* _LINUX_VIRTIO_CONFIG_H */