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1#ifndef _LINUX_VIRTIO_CONFIG_H
2#define _LINUX_VIRTIO_CONFIG_H
3/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
4 * anyone can use the definitions to implement compatible drivers/servers.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of IBM nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE. */
28
29/* Virtio devices use a standardized configuration space to define their
30 * features and pass configuration information, but each implementation can
31 * store and access that space differently. */
32#include <linux/types.h>
33
34/* Status byte for guest to report progress, and synchronize features. */
35/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
36#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
37/* We have found a driver for the device. */
38#define VIRTIO_CONFIG_S_DRIVER 2
39/* Driver has used its parts of the config, and is happy */
40#define VIRTIO_CONFIG_S_DRIVER_OK 4
41/* We've given up on this device. */
42#define VIRTIO_CONFIG_S_FAILED 0x80
43
44/* Some virtio feature bits (currently bits 28 through 31) are reserved for the
45 * transport being used (eg. virtio_ring), the rest are per-device feature
46 * bits. */
47#define VIRTIO_TRANSPORT_F_START 28
48#define VIRTIO_TRANSPORT_F_END 32
49
50/* Do we get callbacks when the ring is completely used, even if we've
51 * suppressed them? */
52#define VIRTIO_F_NOTIFY_ON_EMPTY 24
53
54#ifdef __KERNEL__
55#include <linux/err.h>
56#include <linux/virtio.h>
57
58/**
59 * virtio_config_ops - operations for configuring a virtio device
60 * @get: read the value of a configuration field
61 * vdev: the virtio_device
62 * offset: the offset of the configuration field
63 * buf: the buffer to write the field value into.
64 * len: the length of the buffer
65 * @set: write the value of a configuration field
66 * vdev: the virtio_device
67 * offset: the offset of the configuration field
68 * buf: the buffer to read the field value from.
69 * len: the length of the buffer
70 * @get_status: read the status byte
71 * vdev: the virtio_device
72 * Returns the status byte
73 * @set_status: write the status byte
74 * vdev: the virtio_device
75 * status: the new status byte
76 * @request_vqs: request the specified number of virtqueues
77 * vdev: the virtio_device
78 * max_vqs: the max number of virtqueues we want
79 * If supplied, must call before any virtqueues are instantiated.
80 * To modify the max number of virtqueues after request_vqs has been
81 * called, call free_vqs and then request_vqs with a new value.
82 * @free_vqs: cleanup resources allocated by request_vqs
83 * vdev: the virtio_device
84 * If supplied, must call after all virtqueues have been deleted.
85 * @reset: reset the device
86 * vdev: the virtio device
87 * After this, status and feature negotiation must be done again
88 * Device must not be reset from its vq/config callbacks, or in
89 * parallel with being added/removed.
90 * @find_vqs: find virtqueues and instantiate them.
91 * vdev: the virtio_device
92 * nvqs: the number of virtqueues to find
93 * vqs: on success, includes new virtqueues
94 * callbacks: array of callbacks, for each virtqueue
95 * names: array of virtqueue names (mainly for debugging)
96 * Returns 0 on success or error status
97 * @del_vqs: free virtqueues found by find_vqs().
98 * @get_features: get the array of feature bits for this device.
99 * vdev: the virtio_device
100 * Returns the first 32 feature bits (all we currently need).
101 * @finalize_features: confirm what device features we'll be using.
102 * vdev: the virtio_device
103 * This gives the final feature bits for the device: it can change
104 * the dev->feature bits if it wants.
105 */
106typedef void vq_callback_t(struct virtqueue *);
107struct virtio_config_ops {
108 void (*get)(struct virtio_device *vdev, unsigned offset,
109 void *buf, unsigned len);
110 void (*set)(struct virtio_device *vdev, unsigned offset,
111 const void *buf, unsigned len);
112 u8 (*get_status)(struct virtio_device *vdev);
113 void (*set_status)(struct virtio_device *vdev, u8 status);
114 void (*reset)(struct virtio_device *vdev);
115 int (*find_vqs)(struct virtio_device *, unsigned nvqs,
116 struct virtqueue *vqs[],
117 vq_callback_t *callbacks[],
118 const char *names[]);
119 void (*del_vqs)(struct virtio_device *);
120 u32 (*get_features)(struct virtio_device *vdev);
121 void (*finalize_features)(struct virtio_device *vdev);
122};
123
124/* If driver didn't advertise the feature, it will never appear. */
125void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
126 unsigned int fbit);
127
128/**
129 * virtio_has_feature - helper to determine if this device has this feature.
130 * @vdev: the device
131 * @fbit: the feature bit
132 */
133static inline bool virtio_has_feature(const struct virtio_device *vdev,
134 unsigned int fbit)
135{
136 /* Did you forget to fix assumptions on max features? */
137 if (__builtin_constant_p(fbit))
138 BUILD_BUG_ON(fbit >= 32);
139 else
140 BUG_ON(fbit >= 32);
141
142 if (fbit < VIRTIO_TRANSPORT_F_START)
143 virtio_check_driver_offered_feature(vdev, fbit);
144
145 return test_bit(fbit, vdev->features);
146}
147
148/**
149 * virtio_config_val - look for a feature and get a virtio config entry.
150 * @vdev: the virtio device
151 * @fbit: the feature bit
152 * @offset: the type to search for.
153 * @val: a pointer to the value to fill in.
154 *
155 * The return value is -ENOENT if the feature doesn't exist. Otherwise
156 * the config value is copied into whatever is pointed to by v. */
157#define virtio_config_val(vdev, fbit, offset, v) \
158 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
159
160#define virtio_config_val_len(vdev, fbit, offset, v, len) \
161 virtio_config_buf((vdev), (fbit), (offset), (v), (len))
162
163static inline int virtio_config_buf(struct virtio_device *vdev,
164 unsigned int fbit,
165 unsigned int offset,
166 void *buf, unsigned len)
167{
168 if (!virtio_has_feature(vdev, fbit))
169 return -ENOENT;
170
171 vdev->config->get(vdev, offset, buf, len);
172 return 0;
173}
174
175static inline
176struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
177 vq_callback_t *c, const char *n)
178{
179 vq_callback_t *callbacks[] = { c };
180 const char *names[] = { n };
181 struct virtqueue *vq;
182 int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
183 if (err < 0)
184 return ERR_PTR(err);
185 return vq;
186}
187#endif /* __KERNEL__ */
188#endif /* _LINUX_VIRTIO_CONFIG_H */