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 /* Do we get callbacks when the ring is completely used, even if we've
  19  * suppressed them? */
  20 #define VIRTIO_F_NOTIFY_ON_EMPTY        24
  21
  22 #ifdef __KERNEL__
  23 #include <linux/virtio.h>
  24
  25 /**
  26  * virtio_config_ops - operations for configuring a virtio device
  27  * @get: read the value of a configuration field
  28  *      vdev: the virtio_device
  29  *      offset: the offset of the configuration field
  30  *      buf: the buffer to write the field value into.
  31  *      len: the length of the buffer
  32  * @set: write the value of a configuration field
  33  *      vdev: the virtio_device
  34  *      offset: the offset of the configuration field
  35  *      buf: the buffer to read the field value from.
  36  *      len: the length of the buffer
  37  * @get_status: read the status byte
  38  *      vdev: the virtio_device
  39  *      Returns the status byte
  40  * @set_status: write the status byte
  41  *      vdev: the virtio_device
  42  *      status: the new status byte
  43  * @reset: reset the device
  44  *      vdev: the virtio device
  45  *      After this, status and feature negotiation must be done again
  46  * @find_vq: find a virtqueue and instantiate it.
  47  *      vdev: the virtio_device
  48  *      index: the 0-based virtqueue number in case there's more than one.
  49  *      callback: the virqtueue callback
  50  *      Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
  51  * @del_vq: free a virtqueue found by find_vq().
  52  * @get_features: get the array of feature bits for this device.
  53  *      vdev: the virtio_device
  54  *      Returns the first 32 feature bits (all we currently need).
  55  * @set_features: confirm what device features we'll be using.
  56  *      vdev: the virtio_device
  57  *      feature: the first 32 feature bits
  58  */
  59 struct virtio_config_ops
  60 {
  61         void (*get)(struct virtio_device *vdev, unsigned offset,
  62                     void *buf, unsigned len);
  63         void (*set)(struct virtio_device *vdev, unsigned offset,
  64                     const void *buf, unsigned len);
  65         u8 (*get_status)(struct virtio_device *vdev);
  66         void (*set_status)(struct virtio_device *vdev, u8 status);
  67         void (*reset)(struct virtio_device *vdev);
  68         struct virtqueue *(*find_vq)(struct virtio_device *vdev,
  69                                      unsigned index,
  70                                      void (*callback)(struct virtqueue *));
  71         void (*del_vq)(struct virtqueue *vq);
  72         u32 (*get_features)(struct virtio_device *vdev);
  73         void (*set_features)(struct virtio_device *vdev, u32 features);
  74 };
  75
  76 /* If driver didn't advertise the feature, it will never appear. */
  77 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  78                                          unsigned int fbit);
  79
  80 /**
  81  * virtio_has_feature - helper to determine if this device has this feature.
  82  * @vdev: the device
  83  * @fbit: the feature bit
  84  */
  85 static inline bool virtio_has_feature(const struct virtio_device *vdev,
  86                                       unsigned int fbit)
  87 {
  88         /* Did you forget to fix assumptions on max features? */
  89         if (__builtin_constant_p(fbit))
  90                 BUILD_BUG_ON(fbit >= 32);
  91
  92         virtio_check_driver_offered_feature(vdev, fbit);
  93         return test_bit(fbit, vdev->features);
  94 }
  95
  96 /**
  97  * virtio_config_val - look for a feature and get a virtio config entry.
  98  * @vdev: the virtio device
  99  * @fbit: the feature bit
 100  * @offset: the type to search for.
 101  * @val: a pointer to the value to fill in.
 102  *
 103  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
 104  * the config value is copied into whatever is pointed to by v. */
 105 #define virtio_config_val(vdev, fbit, offset, v) \
 106         virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
 107
 108 static inline int virtio_config_buf(struct virtio_device *vdev,
 109                                     unsigned int fbit,
 110                                     unsigned int offset,
 111                                     void *buf, unsigned len)
 112 {
 113         if (!virtio_has_feature(vdev, fbit))
 114                 return -ENOENT;
 115
 116         vdev->config->get(vdev, offset, buf, len);
 117         return 0;
 118 }
 119 #endif /* __KERNEL__ */
 120 #endif /* _LINUX_VIRTIO_CONFIG_H */