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#include <linux/gfp.h>
  11
  12/**
  13 * virtqueue - a queue to register buffers for sending or receiving.
  14 * @list: the chain of virtqueues for this device
  15 * @callback: the function to call when buffers are consumed (can be NULL).
  16 * @name: the name of this virtqueue (mainly for debugging)
  17 * @vdev: the virtio device this queue was created for.
  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        void *priv;
  26};
  27
  28/**
  29 * operations for virtqueue
  30 * virtqueue_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 *      gfp: how to do memory allocations (if necessary).
  37 *      Returns remaining capacity of queue (sg segments) or a negative error.
  38 * virtqueue_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 * virtqueue_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 * virtqueue_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 * virtqueue_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 * virtqueue_detach_unused_buf: detach first unused buffer
  55 *      vq: the struct virtqueue we're talking about.
  56 *      Returns NULL or the "data" token handed to add_buf
  57 *
  58 * Locking rules are straightforward: the driver is responsible for
  59 * locking.  No two operations may be invoked simultaneously, with the exception
  60 * of virtqueue_disable_cb.
  61 *
  62 * All operations can be called in any context.
  63 */
  64
  65int virtqueue_add_buf_gfp(struct virtqueue *vq,
  66                          struct scatterlist sg[],
  67                          unsigned int out_num,
  68                          unsigned int in_num,
  69                          void *data,
  70                          gfp_t gfp);
  71
  72static inline int virtqueue_add_buf(struct virtqueue *vq,
  73                                    struct scatterlist sg[],
  74                                    unsigned int out_num,
  75                                    unsigned int in_num,
  76                                    void *data)
  77{
  78        return virtqueue_add_buf_gfp(vq, sg, out_num, in_num, data, GFP_ATOMIC);
  79}
  80
  81void virtqueue_kick(struct virtqueue *vq);
  82
  83void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
  84
  85void virtqueue_disable_cb(struct virtqueue *vq);
  86
  87bool virtqueue_enable_cb(struct virtqueue *vq);
  88
  89void *virtqueue_detach_unused_buf(struct virtqueue *vq);
  90
  91/**
  92 * virtio_device - representation of a device using virtio
  93 * @index: unique position on the virtio bus
  94 * @dev: underlying device.
  95 * @id: the device type identification (used to match it with a driver).
  96 * @config: the configuration ops for this device.
  97 * @vqs: the list of virtqueues for this device.
  98 * @features: the features supported by both driver and device.
  99 * @priv: private pointer for the driver's use.
 100 */
 101struct virtio_device {
 102        int index;
 103        struct device dev;
 104        struct virtio_device_id id;
 105        struct virtio_config_ops *config;
 106        struct list_head vqs;
 107        /* Note that this is a Linux set_bit-style bitmap. */
 108        unsigned long features[1];
 109        void *priv;
 110};
 111
 112#define dev_to_virtio(dev) container_of(dev, struct virtio_device, dev)
 113int register_virtio_device(struct virtio_device *dev);
 114void unregister_virtio_device(struct virtio_device *dev);
 115
 116/**
 117 * virtio_driver - operations for a virtio I/O driver
 118 * @driver: underlying device driver (populate name and owner).
 119 * @id_table: the ids serviced by this driver.
 120 * @feature_table: an array of feature numbers supported by this device.
 121 * @feature_table_size: number of entries in the feature table array.
 122 * @probe: the function to call when a device is found.  Returns 0 or -errno.
 123 * @remove: the function when a device is removed.
 124 * @config_changed: optional function to call when the device configuration
 125 *    changes; may be called in interrupt context.
 126 */
 127struct virtio_driver {
 128        struct device_driver driver;
 129        const struct virtio_device_id *id_table;
 130        const unsigned int *feature_table;
 131        unsigned int feature_table_size;
 132        int (*probe)(struct virtio_device *dev);
 133        void (*remove)(struct virtio_device *dev);
 134        void (*config_changed)(struct virtio_device *dev);
 135};
 136
 137int register_virtio_driver(struct virtio_driver *drv);
 138void unregister_virtio_driver(struct virtio_driver *drv);
 139#endif /* _LINUX_VIRTIO_H */
 140