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
virtqueue_add_buf(struct virtqueue * vq,struct scatterlist sg[],unsigned int out_num,unsigned int in_num,void * data)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 */
140