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