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/err.h>
  33 #include <linux/virtio.h>
  34
  35 /**
  36  * virtio_config_ops - operations for configuring a virtio device
  37  * @get: read the value of a configuration field
  38  *      vdev: the virtio_device
  39  *      offset: the offset of the configuration field
  40  *      buf: the buffer to write the field value into.
  41  *      len: the length of the buffer
  42  * @set: write the value of a configuration field
  43  *      vdev: the virtio_device
  44  *      offset: the offset of the configuration field
  45  *      buf: the buffer to read the field value from.
  46  *      len: the length of the buffer
  47  * @get_status: read the status byte
  48  *      vdev: the virtio_device
  49  *      Returns the status byte
  50  * @set_status: write the status byte
  51  *      vdev: the virtio_device
  52  *      status: the new status byte
  53  * @request_vqs: request the specified number of virtqueues
  54  *      vdev: the virtio_device
  55  *      max_vqs: the max number of virtqueues we want
  56  *      If supplied, must call before any virtqueues are instantiated.
  57  *      To modify the max number of virtqueues after request_vqs has been
  58  *      called, call free_vqs and then request_vqs with a new value.
  59  * @free_vqs: cleanup resources allocated by request_vqs
  60  *      vdev: the virtio_device
  61  *      If supplied, must call after all virtqueues have been deleted.
  62  * @reset: reset the device
  63  *      vdev: the virtio device
  64  *      After this, status and feature negotiation must be done again
  65  * @find_vqs: find virtqueues and instantiate them.
  66  *      vdev: the virtio_device
  67  *      nvqs: the number of virtqueues to find
  68  *      vqs: on success, includes new virtqueues
  69  *      callbacks: array of callbacks, for each virtqueue
  70  *      names: array of virtqueue names (mainly for debugging)
  71  *      Returns 0 on success or error status
  72  * @del_vqs: free virtqueues found by find_vqs().
  73  * @get_features: get the array of feature bits for this device.
  74  *      vdev: the virtio_device
  75  *      Returns the first 32 feature bits (all we currently need).
  76  * @finalize_features: confirm what device features we'll be using.
  77  *      vdev: the virtio_device
  78  *      This gives the final feature bits for the device: it can change
  79  *      the dev->feature bits if it wants.
  80  */
  81 typedef void vq_callback_t(struct virtqueue *);
  82 struct virtio_config_ops {
  83         void (*get)(struct virtio_device *vdev, unsigned offset,
  84                     void *buf, unsigned len);
  85         void (*set)(struct virtio_device *vdev, unsigned offset,
  86                     const void *buf, unsigned len);
  87         u8 (*get_status)(struct virtio_device *vdev);
  88         void (*set_status)(struct virtio_device *vdev, u8 status);
  89         void (*reset)(struct virtio_device *vdev);
  90         int (*find_vqs)(struct virtio_device *, unsigned nvqs,
  91                         struct virtqueue *vqs[],
  92                         vq_callback_t *callbacks[],
  93                         const char *names[]);
  94         void (*del_vqs)(struct virtio_device *);
  95         u32 (*get_features)(struct virtio_device *vdev);
  96         void (*finalize_features)(struct virtio_device *vdev);
  97 };
  98
  99 /* If driver didn't advertise the feature, it will never appear. */
 100 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 101                                          unsigned int fbit);
 102
 103 /**
 104  * virtio_has_feature - helper to determine if this device has this feature.
 105  * @vdev: the device
 106  * @fbit: the feature bit
 107  */
 108 static inline bool virtio_has_feature(const struct virtio_device *vdev,
 109                                       unsigned int fbit)
 110 {
 111         /* Did you forget to fix assumptions on max features? */
 112         if (__builtin_constant_p(fbit))
 113                 BUILD_BUG_ON(fbit >= 32);
 114
 115         if (fbit < VIRTIO_TRANSPORT_F_START)
 116                 virtio_check_driver_offered_feature(vdev, fbit);
 117
 118         return test_bit(fbit, vdev->features);
 119 }
 120
 121 /**
 122  * virtio_config_val - look for a feature and get a virtio config entry.
 123  * @vdev: the virtio device
 124  * @fbit: the feature bit
 125  * @offset: the type to search for.
 126  * @val: a pointer to the value to fill in.
 127  *
 128  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
 129  * the config value is copied into whatever is pointed to by v. */
 130 #define virtio_config_val(vdev, fbit, offset, v) \
 131         virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
 132
 133 static inline int virtio_config_buf(struct virtio_device *vdev,
 134                                     unsigned int fbit,
 135                                     unsigned int offset,
 136                                     void *buf, unsigned len)
 137 {
 138         if (!virtio_has_feature(vdev, fbit))
 139                 return -ENOENT;
 140
 141         vdev->config->get(vdev, offset, buf, len);
 142         return 0;
 143 }
 144
 145 static inline
 146 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
 147                                         vq_callback_t *c, const char *n)
 148 {
 149         vq_callback_t *callbacks[] = { c };
 150         const char *names[] = { n };
 151         struct virtqueue *vq;
 152         int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
 153         if (err < 0)
 154                 return ERR_PTR(err);
 155         return vq;
 156 }
 157 #endif /* __KERNEL__ */
 158 #endif /* _LINUX_VIRTIO_CONFIG_H */