xref: /openbmc/linux/include/linux/virtio_config.h (revision 6774def6)
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 static inline
100 struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
101 					vq_callback_t *c, const char *n)
102 {
103 	vq_callback_t *callbacks[] = { c };
104 	const char *names[] = { n };
105 	struct virtqueue *vq;
106 	int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
107 	if (err < 0)
108 		return ERR_PTR(err);
109 	return vq;
110 }
111 
112 /**
113  * virtio_device_ready - enable vq use in probe function
114  * @vdev: the device
115  *
116  * Driver must call this to use vqs in the probe function.
117  *
118  * Note: vqs are enabled automatically after probe returns.
119  */
120 static inline
121 void virtio_device_ready(struct virtio_device *dev)
122 {
123 	unsigned status = dev->config->get_status(dev);
124 
125 	BUG_ON(status & VIRTIO_CONFIG_S_DRIVER_OK);
126 	dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
127 }
128 
129 static inline
130 const char *virtio_bus_name(struct virtio_device *vdev)
131 {
132 	if (!vdev->config->bus_name)
133 		return "virtio";
134 	return vdev->config->bus_name(vdev);
135 }
136 
137 /**
138  * virtqueue_set_affinity - setting affinity for a virtqueue
139  * @vq: the virtqueue
140  * @cpu: the cpu no.
141  *
142  * Pay attention the function are best-effort: the affinity hint may not be set
143  * due to config support, irq type and sharing.
144  *
145  */
146 static inline
147 int virtqueue_set_affinity(struct virtqueue *vq, int cpu)
148 {
149 	struct virtio_device *vdev = vq->vdev;
150 	if (vdev->config->set_vq_affinity)
151 		return vdev->config->set_vq_affinity(vq, cpu);
152 	return 0;
153 }
154 
155 /* Config space accessors. */
156 #define virtio_cread(vdev, structname, member, ptr)			\
157 	do {								\
158 		/* Must match the member's type, and be integer */	\
159 		if (!typecheck(typeof((((structname*)0)->member)), *(ptr))) \
160 			(*ptr) = 1;					\
161 									\
162 		switch (sizeof(*ptr)) {					\
163 		case 1:							\
164 			*(ptr) = virtio_cread8(vdev,			\
165 					       offsetof(structname, member)); \
166 			break;						\
167 		case 2:							\
168 			*(ptr) = virtio_cread16(vdev,			\
169 						offsetof(structname, member)); \
170 			break;						\
171 		case 4:							\
172 			*(ptr) = virtio_cread32(vdev,			\
173 						offsetof(structname, member)); \
174 			break;						\
175 		case 8:							\
176 			*(ptr) = virtio_cread64(vdev,			\
177 						offsetof(structname, member)); \
178 			break;						\
179 		default:						\
180 			BUG();						\
181 		}							\
182 	} while(0)
183 
184 /* Config space accessors. */
185 #define virtio_cwrite(vdev, structname, member, ptr)			\
186 	do {								\
187 		/* Must match the member's type, and be integer */	\
188 		if (!typecheck(typeof((((structname*)0)->member)), *(ptr))) \
189 			BUG_ON((*ptr) == 1);				\
190 									\
191 		switch (sizeof(*ptr)) {					\
192 		case 1:							\
193 			virtio_cwrite8(vdev,				\
194 				       offsetof(structname, member),	\
195 				       *(ptr));				\
196 			break;						\
197 		case 2:							\
198 			virtio_cwrite16(vdev,				\
199 					offsetof(structname, member),	\
200 					*(ptr));			\
201 			break;						\
202 		case 4:							\
203 			virtio_cwrite32(vdev,				\
204 					offsetof(structname, member),	\
205 					*(ptr));			\
206 			break;						\
207 		case 8:							\
208 			virtio_cwrite64(vdev,				\
209 					offsetof(structname, member),	\
210 					*(ptr));			\
211 			break;						\
212 		default:						\
213 			BUG();						\
214 		}							\
215 	} while(0)
216 
217 static inline u8 virtio_cread8(struct virtio_device *vdev, unsigned int offset)
218 {
219 	u8 ret;
220 	vdev->config->get(vdev, offset, &ret, sizeof(ret));
221 	return ret;
222 }
223 
224 static inline void virtio_cread_bytes(struct virtio_device *vdev,
225 				      unsigned int offset,
226 				      void *buf, size_t len)
227 {
228 	vdev->config->get(vdev, offset, buf, len);
229 }
230 
231 static inline void virtio_cwrite8(struct virtio_device *vdev,
232 				  unsigned int offset, u8 val)
233 {
234 	vdev->config->set(vdev, offset, &val, sizeof(val));
235 }
236 
237 static inline u16 virtio_cread16(struct virtio_device *vdev,
238 				 unsigned int offset)
239 {
240 	u16 ret;
241 	vdev->config->get(vdev, offset, &ret, sizeof(ret));
242 	return ret;
243 }
244 
245 static inline void virtio_cwrite16(struct virtio_device *vdev,
246 				   unsigned int offset, u16 val)
247 {
248 	vdev->config->set(vdev, offset, &val, sizeof(val));
249 }
250 
251 static inline u32 virtio_cread32(struct virtio_device *vdev,
252 				 unsigned int offset)
253 {
254 	u32 ret;
255 	vdev->config->get(vdev, offset, &ret, sizeof(ret));
256 	return ret;
257 }
258 
259 static inline void virtio_cwrite32(struct virtio_device *vdev,
260 				   unsigned int offset, u32 val)
261 {
262 	vdev->config->set(vdev, offset, &val, sizeof(val));
263 }
264 
265 static inline u64 virtio_cread64(struct virtio_device *vdev,
266 				 unsigned int offset)
267 {
268 	u64 ret;
269 	vdev->config->get(vdev, offset, &ret, sizeof(ret));
270 	return ret;
271 }
272 
273 static inline void virtio_cwrite64(struct virtio_device *vdev,
274 				   unsigned int offset, u64 val)
275 {
276 	vdev->config->set(vdev, offset, &val, sizeof(val));
277 }
278 
279 /* Conditional config space accessors. */
280 #define virtio_cread_feature(vdev, fbit, structname, member, ptr)	\
281 	({								\
282 		int _r = 0;						\
283 		if (!virtio_has_feature(vdev, fbit))			\
284 			_r = -ENOENT;					\
285 		else							\
286 			virtio_cread((vdev), structname, member, ptr);	\
287 		_r;							\
288 	})
289 
290 #endif /* _LINUX_VIRTIO_CONFIG_H */
291