include/linux/virtio_config.h

   1 #ifndef _LINUX_VIRTIO_CONFIG_H
   2 #define _LINUX_VIRTIO_CONFIG_H
   3
   4 #include <linux/err.h>
   5 #include <linux/bug.h>
   6 #include <linux/virtio.h>
   7 #include <uapi/linux/virtio_config.h>
   8
   9 /**
  10  * virtio_config_ops - operations for configuring a virtio device
  11  * @get: read the value of a configuration field
  12  *      vdev: the virtio_device
  13  *      offset: the offset of the configuration field
  14  *      buf: the buffer to write the field value into.
  15  *      len: the length of the buffer
  16  * @set: write the value of a configuration field
  17  *      vdev: the virtio_device
  18  *      offset: the offset of the configuration field
  19  *      buf: the buffer to read the field value from.
  20  *      len: the length of the buffer
  21  * @get_status: read the status byte
  22  *      vdev: the virtio_device
  23  *      Returns the status byte
  24  * @set_status: write the status byte
  25  *      vdev: the virtio_device
  26  *      status: the new status byte
  27  * @reset: reset the device
  28  *      vdev: the virtio device
  29  *      After this, status and feature negotiation must be done again
  30  *      Device must not be reset from its vq/config callbacks, or in
  31  *      parallel with being added/removed.
  32  * @find_vqs: find virtqueues and instantiate them.
  33  *      vdev: the virtio_device
  34  *      nvqs: the number of virtqueues to find
  35  *      vqs: on success, includes new virtqueues
  36  *      callbacks: array of callbacks, for each virtqueue
  37  *              include a NULL entry for vqs that do not need a callback
  38  *      names: array of virtqueue names (mainly for debugging)
  39  *              include a NULL entry for vqs unused by driver
  40  *      Returns 0 on success or error status
  41  * @del_vqs: free virtqueues found by find_vqs().
  42  * @get_features: get the array of feature bits for this device.
  43  *      vdev: the virtio_device
  44  *      Returns the first 32 feature bits (all we currently need).
  45  * @finalize_features: confirm what device features we'll be using.
  46  *      vdev: the virtio_device
  47  *      This gives the final feature bits for the device: it can change
  48  *      the dev->feature bits if it wants.
  49  * @bus_name: return the bus name associated with the device
  50  *      vdev: the virtio_device
  51  *      This returns a pointer to the bus name a la pci_name from which
  52  *      the caller can then copy.
  53  * @set_vq_affinity: set the affinity for a virtqueue.
  54  */
  55 typedef void vq_callback_t(struct virtqueue *);
  56 struct virtio_config_ops {
  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         int (*find_vqs)(struct virtio_device *, unsigned nvqs,
  65                         struct virtqueue *vqs[],
  66                         vq_callback_t *callbacks[],
  67                         const char *names[]);
  68         void (*del_vqs)(struct virtio_device *);
  69         u32 (*get_features)(struct virtio_device *vdev);
  70         void (*finalize_features)(struct virtio_device *vdev);
  71         const char *(*bus_name)(struct virtio_device *vdev);
  72         int (*set_vq_affinity)(struct virtqueue *vq, int cpu);
  73 };
  74
  75 /* If driver didn't advertise the feature, it will never appear. */
  76 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
  77                                          unsigned int fbit);
  78
  79 /**
  80  * virtio_has_feature - helper to determine if this device has this feature.
  81  * @vdev: the device
  82  * @fbit: the feature bit
  83  */
  84 static inline bool virtio_has_feature(const struct virtio_device *vdev,
  85                                       unsigned int fbit)
  86 {
  87         /* Did you forget to fix assumptions on max features? */
  88         if (__builtin_constant_p(fbit))
  89                 BUILD_BUG_ON(fbit >= 32);
  90         else
  91                 BUG_ON(fbit >= 32);
  92
  93         if (fbit < VIRTIO_TRANSPORT_F_START)
  94                 virtio_check_driver_offered_feature(vdev, fbit);
  95
  96         return test_bit(fbit, vdev->features);
  97 }
  98
  99 /**
 100  * virtio_config_val - look for a feature and get a virtio config entry.
 101  * @vdev: the virtio device
 102  * @fbit: the feature bit
 103  * @offset: the type to search for.
 104  * @v: a pointer to the value to fill in.
 105  *
 106  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
 107  * the config value is copied into whatever is pointed to by v. */
 108 #define virtio_config_val(vdev, fbit, offset, v) \
 109         virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
 110
 111 #define virtio_config_val_len(vdev, fbit, offset, v, len) \
 112         virtio_config_buf((vdev), (fbit), (offset), (v), (len))
 113
 114 static inline int virtio_config_buf(struct virtio_device *vdev,
 115                                     unsigned int fbit,
 116                                     unsigned int offset,
 117                                     void *buf, unsigned len)
 118 {
 119         if (!virtio_has_feature(vdev, fbit))
 120                 return -ENOENT;
 121
 122         vdev->config->get(vdev, offset, buf, len);
 123         return 0;
 124 }
 125
 126 static inline
 127 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
 128                                         vq_callback_t *c, const char *n)
 129 {
 130         vq_callback_t *callbacks[] = { c };
 131         const char *names[] = { n };
 132         struct virtqueue *vq;
 133         int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
 134         if (err < 0)
 135                 return ERR_PTR(err);
 136         return vq;
 137 }
 138
 139 static inline
 140 const char *virtio_bus_name(struct virtio_device *vdev)
 141 {
 142         if (!vdev->config->bus_name)
 143                 return "virtio";
 144         return vdev->config->bus_name(vdev);
 145 }
 146
 147 /**
 148  * virtqueue_set_affinity - setting affinity for a virtqueue
 149  * @vq: the virtqueue
 150  * @cpu: the cpu no.
 151  *
 152  * Pay attention the function are best-effort: the affinity hint may not be set
 153  * due to config support, irq type and sharing.
 154  *
 155  */
 156 static inline
 157 int virtqueue_set_affinity(struct virtqueue *vq, int cpu)
 158 {
 159         struct virtio_device *vdev = vq->vdev;
 160         if (vdev->config->set_vq_affinity)
 161                 return vdev->config->set_vq_affinity(vq, cpu);
 162         return 0;
 163 }
 164
 165
 166 #endif /* _LINUX_VIRTIO_CONFIG_H */