xref: /openbmc/linux/include/linux/virtio_config.h (revision e23feb16)
1 #ifndef _LINUX_VIRTIO_CONFIG_H
2 #define _LINUX_VIRTIO_CONFIG_H
3 
4 #include <linux/err.h>
5 #include <linux/bug.h>
6 #include <linux/virtio.h>
7 #include <uapi/linux/virtio_config.h>
8 
9 /**
10  * virtio_config_ops - operations for configuring a virtio device
11  * @get: read the value of a configuration field
12  *	vdev: the virtio_device
13  *	offset: the offset of the configuration field
14  *	buf: the buffer to write the field value into.
15  *	len: the length of the buffer
16  * @set: write the value of a configuration field
17  *	vdev: the virtio_device
18  *	offset: the offset of the configuration field
19  *	buf: the buffer to read the field value from.
20  *	len: the length of the buffer
21  * @get_status: read the status byte
22  *	vdev: the virtio_device
23  *	Returns the status byte
24  * @set_status: write the status byte
25  *	vdev: the virtio_device
26  *	status: the new status byte
27  * @reset: reset the device
28  *	vdev: the virtio device
29  *	After this, status and feature negotiation must be done again
30  *	Device must not be reset from its vq/config callbacks, or in
31  *	parallel with being added/removed.
32  * @find_vqs: find virtqueues and instantiate them.
33  *	vdev: the virtio_device
34  *	nvqs: the number of virtqueues to find
35  *	vqs: on success, includes new virtqueues
36  *	callbacks: array of callbacks, for each virtqueue
37  *		include a NULL entry for vqs that do not need a callback
38  *	names: array of virtqueue names (mainly for debugging)
39  *		include a NULL entry for vqs unused by driver
40  *	Returns 0 on success or error status
41  * @del_vqs: free virtqueues found by find_vqs().
42  * @get_features: get the array of feature bits for this device.
43  *	vdev: the virtio_device
44  *	Returns the first 32 feature bits (all we currently need).
45  * @finalize_features: confirm what device features we'll be using.
46  *	vdev: the virtio_device
47  *	This gives the final feature bits for the device: it can change
48  *	the dev->feature bits if it wants.
49  * @bus_name: return the bus name associated with the device
50  *	vdev: the virtio_device
51  *      This returns a pointer to the bus name a la pci_name from which
52  *      the caller can then copy.
53  * @set_vq_affinity: set the affinity for a virtqueue.
54  */
55 typedef void vq_callback_t(struct virtqueue *);
56 struct virtio_config_ops {
57 	void (*get)(struct virtio_device *vdev, unsigned offset,
58 		    void *buf, unsigned len);
59 	void (*set)(struct virtio_device *vdev, unsigned offset,
60 		    const void *buf, unsigned len);
61 	u8 (*get_status)(struct virtio_device *vdev);
62 	void (*set_status)(struct virtio_device *vdev, u8 status);
63 	void (*reset)(struct virtio_device *vdev);
64 	int (*find_vqs)(struct virtio_device *, unsigned nvqs,
65 			struct virtqueue *vqs[],
66 			vq_callback_t *callbacks[],
67 			const char *names[]);
68 	void (*del_vqs)(struct virtio_device *);
69 	u32 (*get_features)(struct virtio_device *vdev);
70 	void (*finalize_features)(struct virtio_device *vdev);
71 	const char *(*bus_name)(struct virtio_device *vdev);
72 	int (*set_vq_affinity)(struct virtqueue *vq, int cpu);
73 };
74 
75 /* If driver didn't advertise the feature, it will never appear. */
76 void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
77 					 unsigned int fbit);
78 
79 /**
80  * virtio_has_feature - helper to determine if this device has this feature.
81  * @vdev: the device
82  * @fbit: the feature bit
83  */
84 static inline bool virtio_has_feature(const struct virtio_device *vdev,
85 				      unsigned int fbit)
86 {
87 	/* Did you forget to fix assumptions on max features? */
88 	if (__builtin_constant_p(fbit))
89 		BUILD_BUG_ON(fbit >= 32);
90 	else
91 		BUG_ON(fbit >= 32);
92 
93 	if (fbit < VIRTIO_TRANSPORT_F_START)
94 		virtio_check_driver_offered_feature(vdev, fbit);
95 
96 	return test_bit(fbit, vdev->features);
97 }
98 
99 /**
100  * virtio_config_val - look for a feature and get a virtio config entry.
101  * @vdev: the virtio device
102  * @fbit: the feature bit
103  * @offset: the type to search for.
104  * @v: a pointer to the value to fill in.
105  *
106  * The return value is -ENOENT if the feature doesn't exist.  Otherwise
107  * the config value is copied into whatever is pointed to by v. */
108 #define virtio_config_val(vdev, fbit, offset, v) \
109 	virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
110 
111 #define virtio_config_val_len(vdev, fbit, offset, v, len) \
112 	virtio_config_buf((vdev), (fbit), (offset), (v), (len))
113 
114 static inline int virtio_config_buf(struct virtio_device *vdev,
115 				    unsigned int fbit,
116 				    unsigned int offset,
117 				    void *buf, unsigned len)
118 {
119 	if (!virtio_has_feature(vdev, fbit))
120 		return -ENOENT;
121 
122 	vdev->config->get(vdev, offset, buf, len);
123 	return 0;
124 }
125 
126 static inline
127 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
128 					vq_callback_t *c, const char *n)
129 {
130 	vq_callback_t *callbacks[] = { c };
131 	const char *names[] = { n };
132 	struct virtqueue *vq;
133 	int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
134 	if (err < 0)
135 		return ERR_PTR(err);
136 	return vq;
137 }
138 
139 static inline
140 const char *virtio_bus_name(struct virtio_device *vdev)
141 {
142 	if (!vdev->config->bus_name)
143 		return "virtio";
144 	return vdev->config->bus_name(vdev);
145 }
146 
147 /**
148  * virtqueue_set_affinity - setting affinity for a virtqueue
149  * @vq: the virtqueue
150  * @cpu: the cpu no.
151  *
152  * Pay attention the function are best-effort: the affinity hint may not be set
153  * due to config support, irq type and sharing.
154  *
155  */
156 static inline
157 int virtqueue_set_affinity(struct virtqueue *vq, int cpu)
158 {
159 	struct virtio_device *vdev = vq->vdev;
160 	if (vdev->config->set_vq_affinity)
161 		return vdev->config->set_vq_affinity(vq, cpu);
162 	return 0;
163 }
164 
165 
166 #endif /* _LINUX_VIRTIO_CONFIG_H */
167