Linux kernel mirror (for testing)
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linux
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 */
20struct 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 * virtqueue_get_vring_size: return the size of the virtqueue's vring
65 * vq: the struct virtqueue containing the vring of interest.
66 * Returns the size of the vring.
67 *
68 * Locking rules are straightforward: the driver is responsible for
69 * locking. No two operations may be invoked simultaneously, with the exception
70 * of virtqueue_disable_cb.
71 *
72 * All operations can be called in any context.
73 */
74
75int virtqueue_add_buf_gfp(struct virtqueue *vq,
76 struct scatterlist sg[],
77 unsigned int out_num,
78 unsigned int in_num,
79 void *data,
80 gfp_t gfp);
81
82static inline int virtqueue_add_buf(struct virtqueue *vq,
83 struct scatterlist sg[],
84 unsigned int out_num,
85 unsigned int in_num,
86 void *data)
87{
88 return virtqueue_add_buf_gfp(vq, sg, out_num, in_num, data, GFP_ATOMIC);
89}
90
91void virtqueue_kick(struct virtqueue *vq);
92
93void *virtqueue_get_buf(struct virtqueue *vq, unsigned int *len);
94
95void virtqueue_disable_cb(struct virtqueue *vq);
96
97bool virtqueue_enable_cb(struct virtqueue *vq);
98
99bool virtqueue_enable_cb_delayed(struct virtqueue *vq);
100
101void *virtqueue_detach_unused_buf(struct virtqueue *vq);
102
103unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
104
105/**
106 * virtio_device - representation of a device using virtio
107 * @index: unique position on the virtio bus
108 * @dev: underlying device.
109 * @id: the device type identification (used to match it with a driver).
110 * @config: the configuration ops for this device.
111 * @vqs: the list of virtqueues for this device.
112 * @features: the features supported by both driver and device.
113 * @priv: private pointer for the driver's use.
114 */
115struct virtio_device {
116 int index;
117 struct device dev;
118 struct virtio_device_id id;
119 struct virtio_config_ops *config;
120 struct list_head vqs;
121 /* Note that this is a Linux set_bit-style bitmap. */
122 unsigned long features[1];
123 void *priv;
124};
125
126#define dev_to_virtio(dev) container_of(dev, struct virtio_device, dev)
127int register_virtio_device(struct virtio_device *dev);
128void unregister_virtio_device(struct virtio_device *dev);
129
130/**
131 * virtio_driver - operations for a virtio I/O driver
132 * @driver: underlying device driver (populate name and owner).
133 * @id_table: the ids serviced by this driver.
134 * @feature_table: an array of feature numbers supported by this driver.
135 * @feature_table_size: number of entries in the feature table array.
136 * @probe: the function to call when a device is found. Returns 0 or -errno.
137 * @remove: the function to call when a device is removed.
138 * @config_changed: optional function to call when the device configuration
139 * changes; may be called in interrupt context.
140 */
141struct virtio_driver {
142 struct device_driver driver;
143 const struct virtio_device_id *id_table;
144 const unsigned int *feature_table;
145 unsigned int feature_table_size;
146 int (*probe)(struct virtio_device *dev);
147 void (*remove)(struct virtio_device *dev);
148 void (*config_changed)(struct virtio_device *dev);
149};
150
151int register_virtio_driver(struct virtio_driver *drv);
152void unregister_virtio_driver(struct virtio_driver *drv);
153#endif /* _LINUX_VIRTIO_H */