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 * @list: the chain of virtqueues for this device
  14 * @callback: the function to call when buffers are consumed (can be NULL).
  15 * @name: the name of this virtqueue (mainly for debugging)
  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 */
  20struct virtqueue {
  21        struct list_head list;
  22        void (*callback)(struct virtqueue *vq);
  23        const char *name;
  24        struct virtio_device *vdev;
  25        struct virtqueue_ops *vq_ops;
  26        void *priv;
  27};
  28
  29/**
  30 * virtqueue_ops - operations for virtqueue abstraction layer
  31 * @add_buf: expose buffer to other end
  32 *      vq: the struct virtqueue we're talking about.
  33 *      sg: the description of the buffer(s).
  34 *      out_num: the number of sg readable by other side
  35 *      in_num: the number of sg which are writable (after readable ones)
  36 *      data: the token identifying the buffer.
  37 *      Returns remaining capacity of queue (sg segments) or a negative error.
  38 * @kick: update after add_buf
  39 *      vq: the struct virtqueue
  40 *      After one or more add_buf calls, invoke this to kick the other side.
  41 * @get_buf: get the next used buffer
  42 *      vq: the struct virtqueue we're talking about.
  43 *      len: the length written into the buffer
  44 *      Returns NULL or the "data" token handed to add_buf.
  45 * @disable_cb: disable callbacks
  46 *      vq: the struct virtqueue we're talking about.
  47 *      Note that this is not necessarily synchronous, hence unreliable and only
  48 *      useful as an optimization.
  49 * @enable_cb: restart callbacks after disable_cb.
  50 *      vq: the struct virtqueue we're talking about.
  51 *      This re-enables callbacks; it returns "false" if there are pending
  52 *      buffers in the queue, to detect a possible race between the driver
  53 *      checking for more work, and enabling callbacks.
  54 *
  55 * Locking rules are straightforward: the driver is responsible for
  56 * locking.  No two operations may be invoked simultaneously, with the exception
  57 * of @disable_cb.
  58 *
  59 * All operations can be called in any context.
  60 */
  61struct virtqueue_ops {
  62        int (*add_buf)(struct virtqueue *vq,
  63                       struct scatterlist sg[],
  64                       unsigned int out_num,
  65                       unsigned int in_num,
  66                       void *data);
  67
  68        void (*kick)(struct virtqueue *vq);
  69
  70        void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
  71
  72        void (*disable_cb)(struct virtqueue *vq);
  73        bool (*enable_cb)(struct virtqueue *vq);
  74};
  75
  76/**
  77 * virtio_device - representation of a device using virtio
  78 * @index: unique position on the virtio bus
  79 * @dev: underlying device.
  80 * @id: the device type identification (used to match it with a driver).
  81 * @config: the configuration ops for this device.
  82 * @vqs: the list of virtqueues for this device.
  83 * @features: the features supported by both driver and device.
  84 * @priv: private pointer for the driver's use.
  85 */
  86struct virtio_device {
  87        int index;
  88        struct device dev;
  89        struct virtio_device_id id;
  90        struct virtio_config_ops *config;
  91        struct list_head vqs;
  92        /* Note that this is a Linux set_bit-style bitmap. */
  93        unsigned long features[1];
  94        void *priv;
  95};
  96
  97int register_virtio_device(struct virtio_device *dev);
  98void unregister_virtio_device(struct virtio_device *dev);
  99
 100/**
 101 * virtio_driver - operations for a virtio I/O driver
 102 * @driver: underlying device driver (populate name and owner).
 103 * @id_table: the ids serviced by this driver.
 104 * @feature_table: an array of feature numbers supported by this device.
 105 * @feature_table_size: number of entries in the feature table array.
 106 * @probe: the function to call when a device is found.  Returns 0 or -errno.
 107 * @remove: the function when a device is removed.
 108 * @config_changed: optional function to call when the device configuration
 109 *    changes; may be called in interrupt context.
 110 */
 111struct virtio_driver {
 112        struct device_driver driver;
 113        const struct virtio_device_id *id_table;
 114        const unsigned int *feature_table;
 115        unsigned int feature_table_size;
 116        int (*probe)(struct virtio_device *dev);
 117        void (*remove)(struct virtio_device *dev);
 118        void (*config_changed)(struct virtio_device *dev);
 119};
 120
 121int register_virtio_driver(struct virtio_driver *drv);
 122void unregister_virtio_driver(struct virtio_driver *drv);
 123#endif /* _LINUX_VIRTIO_H */
 124