LXR linux/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 * @vdev: the virtio device this queue was created for.
  15 * @vq_ops: the operations for this virtqueue (see below).
  16 * @priv: a pointer for the virtqueue implementation to use.
  17 */
  18struct virtqueue
  19{
  20        void (*callback)(struct virtqueue *vq);
  21        struct virtio_device *vdev;
  22        struct virtqueue_ops *vq_ops;
  23        void *priv;
  24};
  25
  26/**
  27 * virtqueue_ops - operations for virtqueue abstraction layer
  28 * @add_buf: expose buffer to other end
  29 *      vq: the struct virtqueue we're talking about.
  30 *      sg: the description of the buffer(s).
  31 *      out_num: the number of sg readable by other side
  32 *      in_num: the number of sg which are writable (after readable ones)
  33 *      data: the token identifying the buffer.
  34 *      Returns 0 or an error.
  35 * @kick: update after add_buf
  36 *      vq: the struct virtqueue
  37 *      After one or more add_buf calls, invoke this to kick the other side.
  38 * @get_buf: get the next used buffer
  39 *      vq: the struct virtqueue we're talking about.
  40 *      len: the length written into the buffer
  41 *      Returns NULL or the "data" token handed to add_buf.
  42 * @disable_cb: disable callbacks
  43 *      vq: the struct virtqueue we're talking about.
  44 *      Note that this is not necessarily synchronous, hence unreliable and only
  45 *      useful as an optimization.
  46 * @enable_cb: restart callbacks after disable_cb.
  47 *      vq: the struct virtqueue we're talking about.
  48 *      This re-enables callbacks; it returns "false" if there are pending
  49 *      buffers in the queue, to detect a possible race between the driver
  50 *      checking for more work, and enabling callbacks.
  51 *
  52 * Locking rules are straightforward: the driver is responsible for
  53 * locking.  No two operations may be invoked simultaneously, with the exception
  54 * of @disable_cb.
  55 *
  56 * All operations can be called in any context.
  57 */
  58struct virtqueue_ops {
  59        int (*add_buf)(struct virtqueue *vq,
  60                       struct scatterlist sg[],
  61                       unsigned int out_num,
  62                       unsigned int in_num,
  63                       void *data);
  64
  65        void (*kick)(struct virtqueue *vq);
  66
  67        void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
  68
  69        void (*disable_cb)(struct virtqueue *vq);
  70        bool (*enable_cb)(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 * @features: the features supported by both driver and device.
  80 * @priv: private pointer for the driver's use.
  81 */
  82struct virtio_device
  83{
  84        int index;
  85        struct device dev;
  86        struct virtio_device_id id;
  87        struct virtio_config_ops *config;
  88        /* Note that this is a Linux set_bit-style bitmap. */
  89        unsigned long features[1];
  90        void *priv;
  91};
  92
  93int register_virtio_device(struct virtio_device *dev);
  94void unregister_virtio_device(struct virtio_device *dev);
  95
  96/**
  97 * virtio_driver - operations for a virtio I/O driver
  98 * @driver: underlying device driver (populate name and owner).
  99 * @id_table: the ids serviced by this driver.
 100 * @feature_table: an array of feature numbers supported by this device.
 101 * @feature_table_size: number of entries in the feature table array.
 102 * @probe: the function to call when a device is found.  Returns a token for
 103 *    remove, or PTR_ERR().
 104 * @remove: the function when a device is removed.
 105 * @config_changed: optional function to call when the device configuration
 106 *    changes; may be called in interrupt context.
 107 */
 108struct virtio_driver {
 109        struct device_driver driver;
 110        const struct virtio_device_id *id_table;
 111        const unsigned int *feature_table;
 112        unsigned int feature_table_size;
 113        int (*probe)(struct virtio_device *dev);
 114        void (*remove)(struct virtio_device *dev);
 115        void (*config_changed)(struct virtio_device *dev);
 116};
 117
 118int register_virtio_driver(struct virtio_driver *drv);
 119void unregister_virtio_driver(struct virtio_driver *drv);
 120#endif /* _LINUX_VIRTIO_H */
 121