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_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
  65 int 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
  72 static 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
  81 void virtqueue_kick(struct virtqueue *vq);
  82
  83 void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
  84
  85 void virtqueue_disable_cb(struct virtqueue *vq);
  86
  87 bool virtqueue_enable_cb(struct virtqueue *vq);
  88
  89 void *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  */
 101 struct 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)
 113 int register_virtio_device(struct virtio_device *dev);
 114 void 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  */
 127 struct 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
 137 int register_virtio_driver(struct virtio_driver *drv);
 138 void unregister_virtio_driver(struct virtio_driver *drv);
 139 #endif /* _LINUX_VIRTIO_H */