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  */
  18 struct 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  * @enable_cb: restart callbacks after disable_cb.
  45  *      vq: the struct virtqueue we're talking about.
  46  *      This re-enables callbacks; it returns "false" if there are pending
  47  *      buffers in the queue, to detect a possible race between the driver
  48  *      checking for more work, and enabling callbacks.
  49  *
  50  * Locking rules are straightforward: the driver is responsible for
  51  * locking.  No two operations may be invoked simultaneously.
  52  *
  53  * All operations can be called in any context.
  54  */
  55 struct virtqueue_ops {
  56         int (*add_buf)(struct virtqueue *vq,
  57                        struct scatterlist sg[],
  58                        unsigned int out_num,
  59                        unsigned int in_num,
  60                        void *data);
  61
  62         void (*kick)(struct virtqueue *vq);
  63
  64         void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
  65
  66         void (*disable_cb)(struct virtqueue *vq);
  67         bool (*enable_cb)(struct virtqueue *vq);
  68 };
  69
  70 /**
  71  * virtio_device - representation of a device using virtio
  72  * @index: unique position on the virtio bus
  73  * @dev: underlying device.
  74  * @id: the device type identification (used to match it with a driver).
  75  * @config: the configuration ops for this device.
  76  * @priv: private pointer for the driver's use.
  77  */
  78 struct virtio_device
  79 {
  80         int index;
  81         struct device dev;
  82         struct virtio_device_id id;
  83         struct virtio_config_ops *config;
  84         void *priv;
  85 };
  86
  87 int register_virtio_device(struct virtio_device *dev);
  88 void unregister_virtio_device(struct virtio_device *dev);
  89
  90 /**
  91  * virtio_driver - operations for a virtio I/O driver
  92  * @driver: underlying device driver (populate name and owner).
  93  * @id_table: the ids serviced by this driver.
  94  * @probe: the function to call when a device is found.  Returns a token for
  95  *    remove, or PTR_ERR().
  96  * @remove: the function when a device is removed.
  97  * @config_changed: optional function to call when the device configuration
  98  *    changes; may be called in interrupt context.
  99  */
 100 struct virtio_driver {
 101         struct device_driver driver;
 102         const struct virtio_device_id *id_table;
 103         int (*probe)(struct virtio_device *dev);
 104         void (*remove)(struct virtio_device *dev);
 105         void (*config_changed)(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 */