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. */
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>
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
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
24 #define VIRTIO_TRANSPORT_F_START 28
25 #define VIRTIO_TRANSPORT_F_END 32
27 /* Do we get callbacks when the ring is completely used, even if we've
29 #define VIRTIO_F_NOTIFY_ON_EMPTY 24
32 #include <linux/virtio.h>
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 * @set_features: confirm what device features we'll be using.
65 * vdev: the virtio_device
66 * feature: the first 32 feature bits
68 struct virtio_config_ops
70 void (*get
)(struct virtio_device
*vdev
, unsigned offset
,
71 void *buf
, unsigned len
);
72 void (*set
)(struct virtio_device
*vdev
, unsigned offset
,
73 const void *buf
, unsigned len
);
74 u8 (*get_status
)(struct virtio_device
*vdev
);
75 void (*set_status
)(struct virtio_device
*vdev
, u8 status
);
76 void (*reset
)(struct virtio_device
*vdev
);
77 struct virtqueue
*(*find_vq
)(struct virtio_device
*vdev
,
79 void (*callback
)(struct virtqueue
*));
80 void (*del_vq
)(struct virtqueue
*vq
);
81 u32 (*get_features
)(struct virtio_device
*vdev
);
82 void (*set_features
)(struct virtio_device
*vdev
, u32 features
);
85 /* If driver didn't advertise the feature, it will never appear. */
86 void virtio_check_driver_offered_feature(const struct virtio_device
*vdev
,
90 * virtio_has_feature - helper to determine if this device has this feature.
92 * @fbit: the feature bit
94 static inline bool virtio_has_feature(const struct virtio_device
*vdev
,
97 /* Did you forget to fix assumptions on max features? */
98 if (__builtin_constant_p(fbit
))
99 BUILD_BUG_ON(fbit
>= 32);
101 virtio_check_driver_offered_feature(vdev
, fbit
);
102 return test_bit(fbit
, vdev
->features
);
106 * virtio_config_val - look for a feature and get a virtio config entry.
107 * @vdev: the virtio device
108 * @fbit: the feature bit
109 * @offset: the type to search for.
110 * @val: a pointer to the value to fill in.
112 * The return value is -ENOENT if the feature doesn't exist. Otherwise
113 * the config value is copied into whatever is pointed to by v. */
114 #define virtio_config_val(vdev, fbit, offset, v) \
115 virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
117 static inline int virtio_config_buf(struct virtio_device
*vdev
,
120 void *buf
, unsigned len
)
122 if (!virtio_has_feature(vdev
, fbit
))
125 vdev
->config
->get(vdev
, offset
, buf
, len
);
128 #endif /* __KERNEL__ */
129 #endif /* _LINUX_VIRTIO_CONFIG_H */