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/bug.h>
  57 #include <linux/virtio.h>
  58
  59 /**
  60  * virtio_config_ops - operations for configuring a virtio device
  61  * @get: read the value of a configuration field
  62  *      vdev: the virtio_device
  63  *      offset: the offset of the configuration field
  64  *      buf: the buffer to write the field value into.
  65  *      len: the length of the buffer
  66  * @set: write the value of a configuration field
  67  *      vdev: the virtio_device
  68  *      offset: the offset of the configuration field
  69  *      buf: the buffer to read the field value from.
  70  *      len: the length of the buffer
  71  * @get_status: read the status byte
  72  *      vdev: the virtio_device
  73  *      Returns the status byte
  74  * @set_status: write the status byte
  75  *      vdev: the virtio_device
  76  *      status: the new status byte
  77  * @request_vqs: request the specified number of virtqueues
  78  *      vdev: the virtio_device
  79  *      max_vqs: the max number of virtqueues we want
  80  *      If supplied, must call before any virtqueues are instantiated.
  81  *      To modify the max number of virtqueues after request_vqs has been
  82  *      called, call free_vqs and then request_vqs with a new value.
  83  * @free_vqs: cleanup resources allocated by request_vqs
  84  *      vdev: the virtio_device
  85  *      If supplied, must call after all virtqueues have been deleted.
  86  * @reset: reset the device
  87  *      vdev: the virtio device
  88  *      After this, status and feature negotiation must be done again
  89  *      Device must not be reset from its vq/config callbacks, or in
  90  *      parallel with being added/removed.
  91  * @find_vqs: find virtqueues and instantiate them.
  92  *      vdev: the virtio_device
  93  *      nvqs: the number of virtqueues to find
  94  *      vqs: on success, includes new virtqueues
  95  *      callbacks: array of callbacks, for each virtqueue
  96  *      names: array of virtqueue names (mainly for debugging)
  97  *      Returns 0 on success or error status
  98  * @del_vqs: free virtqueues found by find_vqs().
  99  * @get_features: get the array of feature bits for this device.
 100  *      vdev: the virtio_device
 101  *      Returns the first 32 feature bits (all we currently need).
 102  * @finalize_features: confirm what device features we'll be using.
 103  *      vdev: the virtio_device
 104  *      This gives the final feature bits for the device: it can change
 105  *      the dev->feature bits if it wants.
 106  * @bus_name: return the bus name associated with the device
 107  *      vdev: the virtio_device
 108  *      This returns a pointer to the bus name a la pci_name from which
 109  *      the caller can then copy.
 110  */
 111 typedef void vq_callback_t(struct virtqueue *);
 112 struct virtio_config_ops {
 113         void (*get)(struct virtio_device *vdev, unsigned offset,
 114                     void *buf, unsigned len);
 115         void (*set)(struct virtio_device *vdev, unsigned offset,
 116                     const void *buf, unsigned len);
 117         u8 (*get_status)(struct virtio_device *vdev);
 118         void (*set_status)(struct virtio_device *vdev, u8 status);
 119         void (*reset)(struct virtio_device *vdev);
 120         int (*find_vqs)(struct virtio_device *, unsigned nvqs,
 121                         struct virtqueue *vqs[],
 122                         vq_callback_t *callbacks[],
 123                         const char *names[]);
 124         void (*del_vqs)(struct virtio_device *);
 125         u32 (*get_features)(struct virtio_device *vdev);
 126         void (*finalize_features)(struct virtio_device *vdev);
 127         const char *(*bus_name)(struct virtio_device *vdev);
 128 };
 129
 130 /* If driver didn't advertise the feature, it will never appear. */
 131 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
 132                                          unsigned int fbit);
 133
 134 /**
 135  * virtio_has_feature - helper to determine if this device has this feature.
 136  * @vdev: the device
 137  * @fbit: the feature bit
 138  */
 139 static inline bool virtio_has_feature(const struct virtio_device *vdev,
 140                                       unsigned int fbit)
 141 {
 142         /* Did you forget to fix assumptions on max features? */
 143         if (__builtin_constant_p(fbit))
 144                 BUILD_BUG_ON(fbit >= 32);
 145         else
 146                 BUG_ON(fbit >= 32);
 147
 148         if (fbit < VIRTIO_TRANSPORT_F_START)
 149                 virtio_check_driver_offered_feature(vdev, fbit);
 150
 151         return test_bit(fbit, vdev->features);
 152 }
 153
 154 /**
 155  * virtio_config_val - look for a feature and get a virtio config entry.
 156  * @vdev: the virtio device
 157  * @fbit: the feature bit
 158  * @offset: the type to search for.
 159  * @val: a pointer to the value to fill in.
 160  *
 161  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
 162  * the config value is copied into whatever is pointed to by v. */
 163 #define virtio_config_val(vdev, fbit, offset, v) \
 164         virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
 165
 166 #define virtio_config_val_len(vdev, fbit, offset, v, len) \
 167         virtio_config_buf((vdev), (fbit), (offset), (v), (len))
 168
 169 static inline int virtio_config_buf(struct virtio_device *vdev,
 170                                     unsigned int fbit,
 171                                     unsigned int offset,
 172                                     void *buf, unsigned len)
 173 {
 174         if (!virtio_has_feature(vdev, fbit))
 175                 return -ENOENT;
 176
 177         vdev->config->get(vdev, offset, buf, len);
 178         return 0;
 179 }
 180
 181 static inline
 182 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
 183                                         vq_callback_t *c, const char *n)
 184 {
 185         vq_callback_t *callbacks[] = { c };
 186         const char *names[] = { n };
 187         struct virtqueue *vq;
 188         int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
 189         if (err < 0)
 190                 return ERR_PTR(err);
 191         return vq;
 192 }
 193
 194 static inline
 195 const char *virtio_bus_name(struct virtio_device *vdev)
 196 {
 197         if (!vdev->config->bus_name)
 198                 return "virtio";
 199         return vdev->config->bus_name(vdev);
 200 }
 201
 202 #endif /* __KERNEL__ */
 203 #endif /* _LINUX_VIRTIO_CONFIG_H */