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  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the name of IBM nor the names of its contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE. */
  28
  29 /* Virtio devices use a standardized configuration space to define their
  30  * features and pass configuration information, but each implementation can
  31  * store and access that space differently. */
  32 #include <linux/types.h>
  33
  34 /* Status byte for guest to report progress, and synchronize features. */
  35 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
  36 #define VIRTIO_CONFIG_S_ACKNOWLEDGE     1
  37 /* We have found a driver for the device. */
  38 #define VIRTIO_CONFIG_S_DRIVER          2
  39 /* Driver has used its parts of the config, and is happy */
  40 #define VIRTIO_CONFIG_S_DRIVER_OK       4
  41 /* We've given up on this device. */
  42 #define VIRTIO_CONFIG_S_FAILED          0x80
  43
  44 /* Some virtio feature bits (currently bits 28 through 31) are reserved for the
  45  * transport being used (eg. virtio_ring), the rest are per-device feature
  46  * bits. */
  47 #define VIRTIO_TRANSPORT_F_START        28
  48 #define VIRTIO_TRANSPORT_F_END          32
  49
  50 /* Do we get callbacks when the ring is completely used, even if we've
  51  * suppressed them? */
  52 #define VIRTIO_F_NOTIFY_ON_EMPTY        24
  53
  54 #ifdef __KERNEL__
  55 #include <linux/err.h>
  56 #include <linux/virtio.h>
  57
  58 /**
  59  * virtio_config_ops - operations for configuring a virtio device
  60  * @get: read the value of a configuration field
  61  *      vdev: the virtio_device
  62  *      offset: the offset of the configuration field
  63  *      buf: the buffer to write the field value into.
  64  *      len: the length of the buffer
  65  * @set: write the value of a configuration field
  66  *      vdev: the virtio_device
  67  *      offset: the offset of the configuration field
  68  *      buf: the buffer to read the field value from.
  69  *      len: the length of the buffer
  70  * @get_status: read the status byte
  71  *      vdev: the virtio_device
  72  *      Returns the status byte
  73  * @set_status: write the status byte
  74  *      vdev: the virtio_device
  75  *      status: the new status byte
  76  * @request_vqs: request the specified number of virtqueues
  77  *      vdev: the virtio_device
  78  *      max_vqs: the max number of virtqueues we want
  79  *      If supplied, must call before any virtqueues are instantiated.
  80  *      To modify the max number of virtqueues after request_vqs has been
  81  *      called, call free_vqs and then request_vqs with a new value.
  82  * @free_vqs: cleanup resources allocated by request_vqs
  83  *      vdev: the virtio_device
  84  *      If supplied, must call after all virtqueues have been deleted.
  85  * @reset: reset the device
  86  *      vdev: the virtio device
  87  *      After this, status and feature negotiation must be done again
  88  *      Device must not be reset from its vq/config callbacks, or in
  89  *      parallel with being added/removed.
  90  * @find_vqs: find virtqueues and instantiate them.
  91  *      vdev: the virtio_device
  92  *      nvqs: the number of virtqueues to find
  93  *      vqs: on success, includes new virtqueues
  94  *      callbacks: array of callbacks, for each virtqueue
  95  *      names: array of virtqueue names (mainly for debugging)
  96  *      Returns 0 on success or error status
  97  * @del_vqs: free virtqueues found by find_vqs().
  98  * @get_features: get the array of feature bits for this device.
  99  *      vdev: the virtio_device
 100  *      Returns the first 32 feature bits (all we currently need).
 101  * @finalize_features: confirm what device features we'll be using.
 102  *      vdev: the virtio_device
 103  *      This gives the final feature bits for the device: it can change
 104  *      the dev->feature bits if it wants.
 105  */
 106 typedef void vq_callback_t(struct virtqueue *);
 107 struct virtio_config_ops {
 108         void (*get)(struct virtio_device *vdev, unsigned offset,
 109                     void *buf, unsigned len);
 110         void (*set)(struct virtio_device *vdev, unsigned offset,
 111                     const void *buf, unsigned len);
 112         u8 (*get_status)(struct virtio_device *vdev);
 113         void (*set_status)(struct virtio_device *vdev, u8 status);
 114         void (*reset)(struct virtio_device *vdev);
 115         int (*find_vqs)(struct virtio_device *, unsigned nvqs,
 116                         struct virtqueue *vqs[],
 117                         vq_callback_t *callbacks[],
 118                         const char *names[]);
 119         void (*del_vqs)(struct virtio_device *);
 120         u32 (*get_features)(struct virtio_device *vdev);
 121         void (*finalize_features)(struct virtio_device *vdev);
 122 };
 123
 124 /* If driver didn't advertise the feature, it will never appear. */
 125 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 126                                          unsigned int fbit);
 127
 128 /**
 129  * virtio_has_feature - helper to determine if this device has this feature.
 130  * @vdev: the device
 131  * @fbit: the feature bit
 132  */
 133 static inline bool virtio_has_feature(const struct virtio_device *vdev,
 134                                       unsigned int fbit)
 135 {
 136         /* Did you forget to fix assumptions on max features? */
 137         if (__builtin_constant_p(fbit))
 138                 BUILD_BUG_ON(fbit >= 32);
 139         else
 140                 BUG_ON(fbit >= 32);
 141
 142         if (fbit < VIRTIO_TRANSPORT_F_START)
 143                 virtio_check_driver_offered_feature(vdev, fbit);
 144
 145         return test_bit(fbit, vdev->features);
 146 }
 147
 148 /**
 149  * virtio_config_val - look for a feature and get a virtio config entry.
 150  * @vdev: the virtio device
 151  * @fbit: the feature bit
 152  * @offset: the type to search for.
 153  * @val: a pointer to the value to fill in.
 154  *
 155  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
 156  * the config value is copied into whatever is pointed to by v. */
 157 #define virtio_config_val(vdev, fbit, offset, v) \
 158         virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
 159
 160 #define virtio_config_val_len(vdev, fbit, offset, v, len) \
 161         virtio_config_buf((vdev), (fbit), (offset), (v), (len))
 162
 163 static inline int virtio_config_buf(struct virtio_device *vdev,
 164                                     unsigned int fbit,
 165                                     unsigned int offset,
 166                                     void *buf, unsigned len)
 167 {
 168         if (!virtio_has_feature(vdev, fbit))
 169                 return -ENOENT;
 170
 171         vdev->config->get(vdev, offset, buf, len);
 172         return 0;
 173 }
 174
 175 static inline
 176 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
 177                                         vq_callback_t *c, const char *n)
 178 {
 179         vq_callback_t *callbacks[] = { c };
 180         const char *names[] = { n };
 181         struct virtqueue *vq;
 182         int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
 183         if (err < 0)
 184                 return ERR_PTR(err);
 185         return vq;
 186 }
 187 #endif /* __KERNEL__ */
 188 #endif /* _LINUX_VIRTIO_CONFIG_H */