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/bug.h>
57 #include <linux/virtio.h>
58
59 /**
60 * virtio_config_ops - operations for configuring a virtio device
61 * @get: read the value of a configuration field
62 * vdev: the virtio_device
63 * offset: the offset of the configuration field
64 * buf: the buffer to write the field value into.
65 * len: the length of the buffer
66 * @set: write the value of a configuration field
67 * vdev: the virtio_device
68 * offset: the offset of the configuration field
69 * buf: the buffer to read the field value from.
70 * len: the length of the buffer
71 * @get_status: read the status byte
72 * vdev: the virtio_device
73 * Returns the status byte
74 * @set_status: write the status byte
75 * vdev: the virtio_device
76 * status: the new status byte
77 * @request_vqs: request the specified number of virtqueues
78 * vdev: the virtio_device
79 * max_vqs: the max number of virtqueues we want
80 * If supplied, must call before any virtqueues are instantiated.
81 * To modify the max number of virtqueues after request_vqs has been
82 * called, call free_vqs and then request_vqs with a new value.
83 * @free_vqs: cleanup resources allocated by request_vqs
84 * vdev: the virtio_device
85 * If supplied, must call after all virtqueues have been deleted.
86 * @reset: reset the device
87 * vdev: the virtio device
88 * After this, status and feature negotiation must be done again
89 * Device must not be reset from its vq/config callbacks, or in
90 * parallel with being added/removed.
91 * @find_vqs: find virtqueues and instantiate them.
92 * vdev: the virtio_device
93 * nvqs: the number of virtqueues to find
94 * vqs: on success, includes new virtqueues
95 * callbacks: array of callbacks, for each virtqueue
96 * names: array of virtqueue names (mainly for debugging)
97 * Returns 0 on success or error status
98 * @del_vqs: free virtqueues found by find_vqs().
99 * @get_features: get the array of feature bits for this device.
100 * vdev: the virtio_device
101 * Returns the first 32 feature bits (all we currently need).
102 * @finalize_features: confirm what device features we'll be using.
103 * vdev: the virtio_device
104 * This gives the final feature bits for the device: it can change
105 * the dev->feature bits if it wants.
106 * @bus_name: return the bus name associated with the device
107 * vdev: the virtio_device
108 * This returns a pointer to the bus name a la pci_name from which
109 * the caller can then copy.
110 */
111 typedef void vq_callback_t(struct virtqueue *);
112 struct virtio_config_ops {
113 void (*get)(struct virtio_device *vdev, unsigned offset,
114 void *buf, unsigned len);
115 void (*set)(struct virtio_device *vdev, unsigned offset,
116 const void *buf, unsigned len);
117 u8 (*get_status)(struct virtio_device *vdev);
118 void (*set_status)(struct virtio_device *vdev, u8 status);
119 void (*reset)(struct virtio_device *vdev);
120 int (*find_vqs)(struct virtio_device *, unsigned nvqs,
121 struct virtqueue *vqs[],
122 vq_callback_t *callbacks[],
123 const char *names[]);
124 void (*del_vqs)(struct virtio_device *);
125 u32 (*get_features)(struct virtio_device *vdev);
126 void (*finalize_features)(struct virtio_device *vdev);
127 const char *(*bus_name)(struct virtio_device *vdev);
128 };
129
130 /* If driver didn't advertise the feature, it will never appear. */
131 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
132 unsigned int fbit);
133
134 /**
135 * virtio_has_feature - helper to determine if this device has this feature.
136 * @vdev: the device
137 * @fbit: the feature bit
138 */
virtio_has_feature(const struct virtio_device * vdev,unsigned int fbit)139 static inline bool virtio_has_feature(const struct virtio_device *vdev,
140 unsigned int fbit)
141 {
142 /* Did you forget to fix assumptions on max features? */
143 if (__builtin_constant_p(fbit))
144 BUILD_BUG_ON(fbit >= 32);
145 else
146 BUG_ON(fbit >= 32);
147
148 if (fbit < VIRTIO_TRANSPORT_F_START)
149 virtio_check_driver_offered_feature(vdev, fbit);
150
151 return test_bit(fbit, vdev->features);
152 }
153
154 /**
155 * virtio_config_val - look for a feature and get a virtio config entry.
156 * @vdev: the virtio device
157 * @fbit: the feature bit
158 * @offset: the type to search for.
159 * @val: a pointer to the value to fill in.
160 *
161 * The return value is -ENOENT if the feature doesn't exist. Otherwise
162 * the config value is copied into whatever is pointed to by v. */
163 #define virtio_config_val(vdev, fbit, offset, v) \
164 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
165
166 #define virtio_config_val_len(vdev, fbit, offset, v, len) \
167 virtio_config_buf((vdev), (fbit), (offset), (v), (len))
168
virtio_config_buf(struct virtio_device * vdev,unsigned int fbit,unsigned int offset,void * buf,unsigned len)169 static inline int virtio_config_buf(struct virtio_device *vdev,
170 unsigned int fbit,
171 unsigned int offset,
172 void *buf, unsigned len)
173 {
174 if (!virtio_has_feature(vdev, fbit))
175 return -ENOENT;
176
177 vdev->config->get(vdev, offset, buf, len);
178 return 0;
179 }
180
181 static inline
virtio_find_single_vq(struct virtio_device * vdev,vq_callback_t * c,const char * n)182 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
183 vq_callback_t *c, const char *n)
184 {
185 vq_callback_t *callbacks[] = { c };
186 const char *names[] = { n };
187 struct virtqueue *vq;
188 int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
189 if (err < 0)
190 return ERR_PTR(err);
191 return vq;
192 }
193
194 static inline
virtio_bus_name(struct virtio_device * vdev)195 const char *virtio_bus_name(struct virtio_device *vdev)
196 {
197 if (!vdev->config->bus_name)
198 return "virtio";
199 return vdev->config->bus_name(vdev);
200 }
201
202 #endif /* __KERNEL__ */
203 #endif /* _LINUX_VIRTIO_CONFIG_H */
204