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  *      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  */
  58 struct 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  */
  82 struct 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
  93 int register_virtio_device(struct virtio_device *dev);
  94 void 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  */
 108 struct 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
 118 int register_virtio_driver(struct virtio_driver *drv);
 119 void unregister_virtio_driver(struct virtio_driver *drv);
 120 #endif /* _LINUX_VIRTIO_H */