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  */
  20 struct 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_enable_cb_delayed: restart callbacks after disable_cb.
  55  *      vq: the struct virtqueue we're talking about.
  56  *      This re-enables callbacks but hints to the other side to delay
  57  *      interrupts until most of the available buffers have been processed;
  58  *      it returns "false" if there are many pending buffers in the queue,
  59  *      to detect a possible race between the driver checking for more work,
  60  *      and enabling callbacks.
  61  * virtqueue_detach_unused_buf: detach first unused buffer
  62  *      vq: the struct virtqueue we're talking about.
  63  *      Returns NULL or the "data" token handed to add_buf
  64  *
  65  * Locking rules are straightforward: the driver is responsible for
  66  * locking.  No two operations may be invoked simultaneously, with the exception
  67  * of virtqueue_disable_cb.
  68  *
  69  * All operations can be called in any context.
  70  */
  71
  72 int virtqueue_add_buf_gfp(struct virtqueue *vq,
  73                           struct scatterlist sg[],
  74                           unsigned int out_num,
  75                           unsigned int in_num,
  76                           void *data,
  77                           gfp_t gfp);
  78
  79 static inline int virtqueue_add_buf(struct virtqueue *vq,
  80                                     struct scatterlist sg[],
  81                                     unsigned int out_num,
  82                                     unsigned int in_num,
  83                                     void *data)
  84 {
  85         return virtqueue_add_buf_gfp(vq, sg, out_num, in_num, data, GFP_ATOMIC);
  86 }
  87
  88 void virtqueue_kick(struct virtqueue *vq);
  89
  90 void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
  91
  92 void virtqueue_disable_cb(struct virtqueue *vq);
  93
  94 bool virtqueue_enable_cb(struct virtqueue *vq);
  95
  96 bool virtqueue_enable_cb_delayed(struct virtqueue *vq);
  97
  98 void *virtqueue_detach_unused_buf(struct virtqueue *vq);
  99
 100 /**
 101  * virtio_device - representation of a device using virtio
 102  * @index: unique position on the virtio bus
 103  * @dev: underlying device.
 104  * @id: the device type identification (used to match it with a driver).
 105  * @config: the configuration ops for this device.
 106  * @vqs: the list of virtqueues for this device.
 107  * @features: the features supported by both driver and device.
 108  * @priv: private pointer for the driver's use.
 109  */
 110 struct virtio_device {
 111         int index;
 112         struct device dev;
 113         struct virtio_device_id id;
 114         struct virtio_config_ops *config;
 115         struct list_head vqs;
 116         /* Note that this is a Linux set_bit-style bitmap. */
 117         unsigned long features[1];
 118         void *priv;
 119 };
 120
 121 #define dev_to_virtio(dev) container_of(dev, struct virtio_device, dev)
 122 int register_virtio_device(struct virtio_device *dev);
 123 void unregister_virtio_device(struct virtio_device *dev);
 124
 125 /**
 126  * virtio_driver - operations for a virtio I/O driver
 127  * @driver: underlying device driver (populate name and owner).
 128  * @id_table: the ids serviced by this driver.
 129  * @feature_table: an array of feature numbers supported by this driver.
 130  * @feature_table_size: number of entries in the feature table array.
 131  * @probe: the function to call when a device is found.  Returns 0 or -errno.
 132  * @remove: the function to call when a device is removed.
 133  * @config_changed: optional function to call when the device configuration
 134  *    changes; may be called in interrupt context.
 135  */
 136 struct virtio_driver {
 137         struct device_driver driver;
 138         const struct virtio_device_id *id_table;
 139         const unsigned int *feature_table;
 140         unsigned int feature_table_size;
 141         int (*probe)(struct virtio_device *dev);
 142         void (*remove)(struct virtio_device *dev);
 143         void (*config_changed)(struct virtio_device *dev);
 144 };
 145
 146 int register_virtio_driver(struct virtio_driver *drv);
 147 void unregister_virtio_driver(struct virtio_driver *drv);
 148 #endif /* _LINUX_VIRTIO_H */