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/virtio.h>
33
34 /**
35 * virtio_config_ops - operations for configuring a virtio device
36 * @get: read the value of a configuration field
37 * vdev: the virtio_device
38 * offset: the offset of the configuration field
39 * buf: the buffer to write the field value into.
40 * len: the length of the buffer
41 * @set: write the value of a configuration field
42 * vdev: the virtio_device
43 * offset: the offset of the configuration field
44 * buf: the buffer to read the field value from.
45 * len: the length of the buffer
46 * @get_status: read the status byte
47 * vdev: the virtio_device
48 * Returns the status byte
49 * @set_status: write the status byte
50 * vdev: the virtio_device
51 * status: the new status byte
52 * @reset: reset the device
53 * vdev: the virtio device
54 * After this, status and feature negotiation must be done again
55 * @find_vq: find a virtqueue and instantiate it.
56 * vdev: the virtio_device
57 * index: the 0-based virtqueue number in case there's more than one.
58 * callback: the virqtueue callback
59 * Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
60 * @del_vq: free a virtqueue found by find_vq().
61 * @get_features: get the array of feature bits for this device.
62 * vdev: the virtio_device
63 * Returns the first 32 feature bits (all we currently need).
64 * @finalize_features: confirm what device features we'll be using.
65 * vdev: the virtio_device
66 * This gives the final feature bits for the device: it can change
67 * the dev->feature bits if it wants.
68 */
69 struct virtio_config_ops
70 {
71 void (*get)(struct virtio_device *vdev, unsigned offset,
72 void *buf, unsigned len);
73 void (*set)(struct virtio_device *vdev, unsigned offset,
74 const void *buf, unsigned len);
75 u8 (*get_status)(struct virtio_device *vdev);
76 void (*set_status)(struct virtio_device *vdev, u8 status);
77 void (*reset)(struct virtio_device *vdev);
78 struct virtqueue *(*find_vq)(struct virtio_device *vdev,
79 unsigned index,
80 void (*callback)(struct virtqueue *));
81 void (*del_vq)(struct virtqueue *vq);
82 u32 (*get_features)(struct virtio_device *vdev);
83 void (*finalize_features)(struct virtio_device *vdev);
84 };
85
86 /* If driver didn't advertise the feature, it will never appear. */
87 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
88 unsigned int fbit);
89
90 /**
91 * virtio_has_feature - helper to determine if this device has this feature.
92 * @vdev: the device
93 * @fbit: the feature bit
94 */
virtio_has_feature(const struct virtio_device * vdev,unsigned int fbit)95 static inline bool virtio_has_feature(const struct virtio_device *vdev,
96 unsigned int fbit)
97 {
98 /* Did you forget to fix assumptions on max features? */
99 if (__builtin_constant_p(fbit))
100 BUILD_BUG_ON(fbit >= 32);
101
102 virtio_check_driver_offered_feature(vdev, fbit);
103 return test_bit(fbit, vdev->features);
104 }
105
106 /**
107 * virtio_config_val - look for a feature and get a virtio config entry.
108 * @vdev: the virtio device
109 * @fbit: the feature bit
110 * @offset: the type to search for.
111 * @val: a pointer to the value to fill in.
112 *
113 * The return value is -ENOENT if the feature doesn't exist. Otherwise
114 * the config value is copied into whatever is pointed to by v. */
115 #define virtio_config_val(vdev, fbit, offset, v) \
116 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
117
virtio_config_buf(struct virtio_device * vdev,unsigned int fbit,unsigned int offset,void * buf,unsigned len)118 static inline int virtio_config_buf(struct virtio_device *vdev,
119 unsigned int fbit,
120 unsigned int offset,
121 void *buf, unsigned len)
122 {
123 if (!virtio_has_feature(vdev, fbit))
124 return -ENOENT;
125
126 vdev->config->get(vdev, offset, buf, len);
127 return 0;
128 }
129 #endif /* __KERNEL__ */
130 #endif /* _LINUX_VIRTIO_CONFIG_H */
131