include/linux/virtio.h

   1 #ifndef _LINUX_VIRTIO_H
   2 #define _LINUX_VIRTIO_H
   3 /* Everything a virtio driver needs to work with any particular virtio
   4  * implementation. */
   5 #include <linux/types.h>
   6 #include <linux/scatterlist.h>
   7 #include <linux/spinlock.h>
   8 #include <linux/device.h>
   9 #include <linux/mod_devicetable.h>
  10
  11 /**
  12  * virtqueue - a queue to register buffers for sending or receiving.
  13  * @callback: the function to call when buffers are consumed (can be NULL).
  14  *    If this returns false, callbacks are suppressed until vq_ops->restart
  15  *    is called.
  16  * @vdev: the virtio device this queue was created for.
  17  * @vq_ops: the operations for this virtqueue (see below).
  18  * @priv: a pointer for the virtqueue implementation to use.
  19  */
  20 struct virtqueue
  21 {
  22         bool (*callback)(struct virtqueue *vq);
  23         struct virtio_device *vdev;
  24         struct virtqueue_ops *vq_ops;
  25         void *priv;
  26 };
  27
  28 /**
  29  * virtqueue_ops - operations for virtqueue abstraction layer
  30  * @add_buf: expose buffer to other end
  31  *      vq: the struct virtqueue we're talking about.
  32  *      sg: the description of the buffer(s).
  33  *      out_num: the number of sg readable by other side
  34  *      in_num: the number of sg which are writable (after readable ones)
  35  *      data: the token identifying the buffer.
  36  *      Returns 0 or an error.
  37  * @kick: update after add_buf
  38  *      vq: the struct virtqueue
  39  *      After one or more add_buf calls, invoke this to kick the other side.
  40  * @get_buf: get the next used buffer
  41  *      vq: the struct virtqueue we're talking about.
  42  *      len: the length written into the buffer
  43  *      Returns NULL or the "data" token handed to add_buf.
  44  * @restart: restart callbacks after callback returned false.
  45  *      vq: the struct virtqueue we're talking about.
  46  *      This returns "false" (and doesn't re-enable) if there are pending
  47  *      buffers in the queue, to avoid a race.
  48  * @shutdown: "unadd" all buffers.
  49  *      vq: the struct virtqueue we're talking about.
  50  *      Remove everything from the queue.
  51  *
  52  * Locking rules are straightforward: the driver is responsible for
  53  * locking.  No two operations may be invoked simultaneously.
  54  *
  55  * All operations can be called in any context.
  56  */
  57 struct virtqueue_ops {
  58         int (*add_buf)(struct virtqueue *vq,
  59                        struct scatterlist sg[],
  60                        unsigned int out_num,
  61                        unsigned int in_num,
  62                        void *data);
  63
  64         void (*kick)(struct virtqueue *vq);
  65
  66         void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
  67
  68         bool (*restart)(struct virtqueue *vq);
  69
  70         void (*shutdown)(struct virtqueue *vq);
  71 };
  72
  73 /**
  74  * virtio_device - representation of a device using virtio
  75  * @index: unique position on the virtio bus
  76  * @dev: underlying device.
  77  * @id: the device type identification (used to match it with a driver).
  78  * @config: the configuration ops for this device.
  79  * @priv: private pointer for the driver's use.
  80  */
  81 struct virtio_device
  82 {
  83         int index;
  84         struct device dev;
  85         struct virtio_device_id id;
  86         struct virtio_config_ops *config;
  87         void *priv;
  88 };
  89
  90 int register_virtio_device(struct virtio_device *dev);
  91 void unregister_virtio_device(struct virtio_device *dev);
  92
  93 /**
  94  * virtio_driver - operations for a virtio I/O driver
  95  * @driver: underlying device driver (populate name and owner).
  96  * @id_table: the ids serviced by this driver.
  97  * @probe: the function to call when a device is found.  Returns a token for
  98  *    remove, or PTR_ERR().
  99  * @remove: the function when a device is removed.
 100  */
 101 struct virtio_driver {
 102         struct device_driver driver;
 103         const struct virtio_device_id *id_table;
 104         int (*probe)(struct virtio_device *dev);
 105         void (*remove)(struct virtio_device *dev);
 106 };
 107
 108 int register_virtio_driver(struct virtio_driver *drv);
 109 void unregister_virtio_driver(struct virtio_driver *drv);
 110 #endif /* _LINUX_VIRTIO_H */