1 #ifndef _LINUX_VIRTIO_CONFIG_H
2 #define _LINUX_VIRTIO_CONFIG_H
3 /* Virtio devices use a standardized configuration space to define their
4 * features and pass configuration information, but each implementation can
5 * store and access that space differently. */
6 #include <linux/types.h>
7
8 /* Status byte for guest to report progress, and synchronize features. */
9 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
10 #define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
11 /* We have found a driver for the device. */
12 #define VIRTIO_CONFIG_S_DRIVER 2
13 /* Driver has used its parts of the config, and is happy */
14 #define VIRTIO_CONFIG_S_DRIVER_OK 4
15 /* We've given up on this device. */
16 #define VIRTIO_CONFIG_S_FAILED 0x80
17
18 #ifdef __KERNEL__
19 struct virtio_device;
20
21 /**
22 * virtio_config_ops - operations for configuring a virtio device
23 * @feature: search for a feature in this config
24 * vdev: the virtio_device
25 * bit: the feature bit
26 * Returns true if the feature is supported. Acknowledges the feature
27 * so the host can see it.
28 * @get: read the value of a configuration field
29 * vdev: the virtio_device
30 * offset: the offset of the configuration field
31 * buf: the buffer to write the field value into.
32 * len: the length of the buffer
33 * Note that contents are conventionally little-endian.
34 * @set: write the value of a configuration field
35 * vdev: the virtio_device
36 * offset: the offset of the configuration field
37 * buf: the buffer to read the field value from.
38 * len: the length of the buffer
39 * Note that contents are conventionally little-endian.
40 * @get_status: read the status byte
41 * vdev: the virtio_device
42 * Returns the status byte
43 * @set_status: write the status byte
44 * vdev: the virtio_device
45 * status: the new status byte
46 * @reset: reset the device
47 * vdev: the virtio device
48 * After this, status and feature negotiation must be done again
49 * @find_vq: find a virtqueue and instantiate it.
50 * vdev: the virtio_device
51 * index: the 0-based virtqueue number in case there's more than one.
52 * callback: the virqtueue callback
53 * Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
54 * @del_vq: free a virtqueue found by find_vq().
55 */
56 struct virtio_config_ops
57 {
58 bool (*feature)(struct virtio_device *vdev, unsigned bit);
59 void (*get)(struct virtio_device *vdev, unsigned offset,
60 void *buf, unsigned len);
61 void (*set)(struct virtio_device *vdev, unsigned offset,
62 const void *buf, unsigned len);
63 u8 (*get_status)(struct virtio_device *vdev);
64 void (*set_status)(struct virtio_device *vdev, u8 status);
65 void (*reset)(struct virtio_device *vdev);
66 struct virtqueue *(*find_vq)(struct virtio_device *vdev,
67 unsigned index,
68 void (*callback)(struct virtqueue *));
69 void (*del_vq)(struct virtqueue *vq);
70 };
71
72 /**
73 * virtio_config_val - look for a feature and get a single virtio config.
74 * @vdev: the virtio device
75 * @fbit: the feature bit
76 * @offset: the type to search for.
77 * @val: a pointer to the value to fill in.
78 *
79 * The return value is -ENOENT if the feature doesn't exist. Otherwise
80 * the value is endian-corrected and returned in v. */
81 #define virtio_config_val(vdev, fbit, offset, v) ({ \
82 int _err; \
83 if ((vdev)->config->feature((vdev), (fbit))) { \
84 __virtio_config_val((vdev), (offset), (v)); \
85 _err = 0; \
86 } else \
87 _err = -ENOENT; \
88 _err; \
89 })
90
91 /**
92 * __virtio_config_val - get a single virtio config without feature check.
93 * @vdev: the virtio device
94 * @offset: the type to search for.
95 * @val: a pointer to the value to fill in.
96 *
97 * The value is endian-corrected and returned in v. */
98 #define __virtio_config_val(vdev, offset, v) do { \
99 BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
100 && sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
101 (vdev)->config->get((vdev), (offset), (v), sizeof(*(v))); \
102 switch (sizeof(*(v))) { \
103 case 2: le16_to_cpus((__u16 *) v); break; \
104 case 4: le32_to_cpus((__u32 *) v); break; \
105 case 8: le64_to_cpus((__u64 *) v); break; \
106 } \
107 } while(0)
108 #endif /* __KERNEL__ */
109 #endif /* _LINUX_VIRTIO_CONFIG_H */
110
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