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  */
  20 struct 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  */
  61 struct 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  */
  86 struct 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
  97 int register_virtio_device(struct virtio_device *dev);
  98 void 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  */
 111 struct 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
 121 int register_virtio_driver(struct virtio_driver *drv);
 122 void unregister_virtio_driver(struct virtio_driver *drv);
 123 #endif /* _LINUX_VIRTIO_H */