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 /* Virtio devices use a standardized configuration space to define their
7 * features and pass configuration information, but each implementation can
8 * store and access that space differently. */
9 #include <linux/types.h>
10
11 /* Status byte for guest to report progress, and synchronize features. */
12 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
13 #define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
14 /* We have found a driver for the device. */
15 #define VIRTIO_CONFIG_S_DRIVER 2
16 /* Driver has used its parts of the config, and is happy */
17 #define VIRTIO_CONFIG_S_DRIVER_OK 4
18 /* We've given up on this device. */
19 #define VIRTIO_CONFIG_S_FAILED 0x80
20
21 /* Some virtio feature bits (currently bits 28 through 31) are reserved for the
22 * transport being used (eg. virtio_ring), the rest are per-device feature
23 * bits. */
24 #define VIRTIO_TRANSPORT_F_START 28
25 #define VIRTIO_TRANSPORT_F_END 32
26
27 /* Do we get callbacks when the ring is completely used, even if we've
28 * suppressed them? */
29 #define VIRTIO_F_NOTIFY_ON_EMPTY 24
30
31 #ifdef __KERNEL__
32 #include <linux/err.h>
33 #include <linux/virtio.h>
34
35 /**
36 * virtio_config_ops - operations for configuring a virtio device
37 * @get: read the value of a configuration field
38 * vdev: the virtio_device
39 * offset: the offset of the configuration field
40 * buf: the buffer to write the field value into.
41 * len: the length of the buffer
42 * @set: write the value of a configuration field
43 * vdev: the virtio_device
44 * offset: the offset of the configuration field
45 * buf: the buffer to read the field value from.
46 * len: the length of the buffer
47 * @get_status: read the status byte
48 * vdev: the virtio_device
49 * Returns the status byte
50 * @set_status: write the status byte
51 * vdev: the virtio_device
52 * status: the new status byte
53 * @request_vqs: request the specified number of virtqueues
54 * vdev: the virtio_device
55 * max_vqs: the max number of virtqueues we want
56 * If supplied, must call before any virtqueues are instantiated.
57 * To modify the max number of virtqueues after request_vqs has been
58 * called, call free_vqs and then request_vqs with a new value.
59 * @free_vqs: cleanup resources allocated by request_vqs
60 * vdev: the virtio_device
61 * If supplied, must call after all virtqueues have been deleted.
62 * @reset: reset the device
63 * vdev: the virtio device
64 * After this, status and feature negotiation must be done again
65 * @find_vqs: find virtqueues and instantiate them.
66 * vdev: the virtio_device
67 * nvqs: the number of virtqueues to find
68 * vqs: on success, includes new virtqueues
69 * callbacks: array of callbacks, for each virtqueue
70 * names: array of virtqueue names (mainly for debugging)
71 * Returns 0 on success or error status
72 * @del_vqs: free virtqueues found by find_vqs().
73 * @get_features: get the array of feature bits for this device.
74 * vdev: the virtio_device
75 * Returns the first 32 feature bits (all we currently need).
76 * @finalize_features: confirm what device features we'll be using.
77 * vdev: the virtio_device
78 * This gives the final feature bits for the device: it can change
79 * the dev->feature bits if it wants.
80 */
81 typedef void vq_callback_t(struct virtqueue *);
82 struct virtio_config_ops {
83 void (*get)(struct virtio_device *vdev, unsigned offset,
84 void *buf, unsigned len);
85 void (*set)(struct virtio_device *vdev, unsigned offset,
86 const void *buf, unsigned len);
87 u8 (*get_status)(struct virtio_device *vdev);
88 void (*set_status)(struct virtio_device *vdev, u8 status);
89 void (*reset)(struct virtio_device *vdev);
90 int (*find_vqs)(struct virtio_device *, unsigned nvqs,
91 struct virtqueue *vqs[],
92 vq_callback_t *callbacks[],
93 const char *names[]);
94 void (*del_vqs)(struct virtio_device *);
95 u32 (*get_features)(struct virtio_device *vdev);
96 void (*finalize_features)(struct virtio_device *vdev);
97 };
98
99 /* If driver didn't advertise the feature, it will never appear. */
100 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
101 unsigned int fbit);
102
103 /**
104 * virtio_has_feature - helper to determine if this device has this feature.
105 * @vdev: the device
106 * @fbit: the feature bit
107 */
virtio_has_feature(const struct virtio_device * vdev,unsigned int fbit)108 static inline bool virtio_has_feature(const struct virtio_device *vdev,
109 unsigned int fbit)
110 {
111 /* Did you forget to fix assumptions on max features? */
112 if (__builtin_constant_p(fbit))
113 BUILD_BUG_ON(fbit >= 32);
114 else
115 BUG_ON(fbit >= 32);
116
117 if (fbit < VIRTIO_TRANSPORT_F_START)
118 virtio_check_driver_offered_feature(vdev, fbit);
119
120 return test_bit(fbit, vdev->features);
121 }
122
123 /**
124 * virtio_config_val - look for a feature and get a virtio config entry.
125 * @vdev: the virtio device
126 * @fbit: the feature bit
127 * @offset: the type to search for.
128 * @val: a pointer to the value to fill in.
129 *
130 * The return value is -ENOENT if the feature doesn't exist. Otherwise
131 * the config value is copied into whatever is pointed to by v. */
132 #define virtio_config_val(vdev, fbit, offset, v) \
133 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
134
virtio_config_buf(struct virtio_device * vdev,unsigned int fbit,unsigned int offset,void * buf,unsigned len)135 static inline int virtio_config_buf(struct virtio_device *vdev,
136 unsigned int fbit,
137 unsigned int offset,
138 void *buf, unsigned len)
139 {
140 if (!virtio_has_feature(vdev, fbit))
141 return -ENOENT;
142
143 vdev->config->get(vdev, offset, buf, len);
144 return 0;
145 }
146
147 static inline
virtio_find_single_vq(struct virtio_device * vdev,vq_callback_t * c,const char * n)148 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
149 vq_callback_t *c, const char *n)
150 {
151 vq_callback_t *callbacks[] = { c };
152 const char *names[] = { n };
153 struct virtqueue *vq;
154 int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
155 if (err < 0)
156 return ERR_PTR(err);
157 return vq;
158 }
159 #endif /* __KERNEL__ */
160 #endif /* _LINUX_VIRTIO_CONFIG_H */
161