1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * virtio-snd: Virtio sound device
4 * Copyright (C) 2021 OpenSynergy GmbH
5 */
6 #include <linux/moduleparam.h>
7 #include <linux/virtio_config.h>
8
9 #include "virtio_card.h"
10
11 /**
12 * struct virtio_snd_msg - Control message.
13 * @sg_request: Scattergather list containing a device request (header).
14 * @sg_response: Scattergather list containing a device response (status).
15 * @list: Pending message list entry.
16 * @notify: Request completed notification.
17 * @ref_count: Reference count used to manage a message lifetime.
18 */
19 struct virtio_snd_msg {
20 struct scatterlist sg_request;
21 struct scatterlist sg_response;
22 struct list_head list;
23 struct completion notify;
24 refcount_t ref_count;
25 };
26
27 /**
28 * virtsnd_ctl_msg_ref() - Increment reference counter for the message.
29 * @msg: Control message.
30 *
31 * Context: Any context.
32 */
33 void virtsnd_ctl_msg_ref(struct virtio_snd_msg *msg)
34 {
35 refcount_inc(&msg->ref_count);
36 }
37
38 /**
39 * virtsnd_ctl_msg_unref() - Decrement reference counter for the message.
40 * @msg: Control message.
41 *
42 * The message will be freed when the ref_count value is 0.
43 *
44 * Context: Any context.
45 */
46 void virtsnd_ctl_msg_unref(struct virtio_snd_msg *msg)
47 {
48 if (refcount_dec_and_test(&msg->ref_count))
49 kfree(msg);
50 }
51
52 /**
53 * virtsnd_ctl_msg_request() - Get a pointer to the request header.
54 * @msg: Control message.
55 *
56 * Context: Any context.
57 */
58 void *virtsnd_ctl_msg_request(struct virtio_snd_msg *msg)
59 {
60 return sg_virt(&msg->sg_request);
61 }
62
63 /**
64 * virtsnd_ctl_msg_response() - Get a pointer to the response header.
65 * @msg: Control message.
66 *
67 * Context: Any context.
68 */
69 void *virtsnd_ctl_msg_response(struct virtio_snd_msg *msg)
70 {
71 return sg_virt(&msg->sg_response);
72 }
73
74 /**
75 * virtsnd_ctl_msg_alloc() - Allocate and initialize a control message.
76 * @request_size: Size of request header.
77 * @response_size: Size of response header.
78 * @gfp: Kernel flags for memory allocation.
79 *
80 * The message will be automatically freed when the ref_count value is 0.
81 *
82 * Context: Any context. May sleep if @gfp flags permit.
83 * Return: Allocated message on success, NULL on failure.
84 */
85 struct virtio_snd_msg *virtsnd_ctl_msg_alloc(size_t request_size,
86 size_t response_size, gfp_t gfp)
87 {
88 struct virtio_snd_msg *msg;
89
90 if (!request_size || !response_size)
91 return NULL;
92
93 msg = kzalloc(sizeof(*msg) + request_size + response_size, gfp);
94 if (!msg)
95 return NULL;
96
97 sg_init_one(&msg->sg_request, (u8 *)msg + sizeof(*msg), request_size);
98 sg_init_one(&msg->sg_response, (u8 *)msg + sizeof(*msg) + request_size,
99 response_size);
100
101 INIT_LIST_HEAD(&msg->list);
102 init_completion(&msg->notify);
103 /* This reference is dropped in virtsnd_ctl_msg_complete(). */
104 refcount_set(&msg->ref_count, 1);
105
106 return msg;
107 }
108
109 /**
110 * virtsnd_ctl_msg_send() - Send a control message.
111 * @snd: VirtIO sound device.
112 * @msg: Control message.
113 * @out_sgs: Additional sg-list to attach to the request header (may be NULL).
114 * @in_sgs: Additional sg-list to attach to the response header (may be NULL).
115 * @nowait: Flag indicating whether to wait for completion.
116 *
117 * Context: Any context. Takes and releases the control queue spinlock.
118 * May sleep if @nowait is false.
119 * Return: 0 on success, -errno on failure.
120 */
121 int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg,
122 struct scatterlist *out_sgs,
123 struct scatterlist *in_sgs, bool nowait)
124 {
125 struct virtio_device *vdev = snd->vdev;
126 struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
127 unsigned int js = msecs_to_jiffies(virtsnd_msg_timeout_ms);
128 struct virtio_snd_hdr *request = virtsnd_ctl_msg_request(msg);
129 struct virtio_snd_hdr *response = virtsnd_ctl_msg_response(msg);
130 unsigned int nouts = 0;
131 unsigned int nins = 0;
132 struct scatterlist *psgs[4];
133 bool notify = false;
134 unsigned long flags;
135 int rc;
136
137 virtsnd_ctl_msg_ref(msg);
138
139 /* Set the default status in case the message was canceled. */
140 response->code = cpu_to_le32(VIRTIO_SND_S_IO_ERR);
141
142 psgs[nouts++] = &msg->sg_request;
143 if (out_sgs)
144 psgs[nouts++] = out_sgs;
145
146 psgs[nouts + nins++] = &msg->sg_response;
147 if (in_sgs)
148 psgs[nouts + nins++] = in_sgs;
149
150 spin_lock_irqsave(&queue->lock, flags);
151 rc = virtqueue_add_sgs(queue->vqueue, psgs, nouts, nins, msg,
152 GFP_ATOMIC);
153 if (!rc) {
154 notify = virtqueue_kick_prepare(queue->vqueue);
155
156 list_add_tail(&msg->list, &snd->ctl_msgs);
157 }
158 spin_unlock_irqrestore(&queue->lock, flags);
159
160 if (rc) {
161 dev_err(&vdev->dev, "failed to send control message (0x%08x)\n",
162 le32_to_cpu(request->code));
163
164 /*
165 * Since in this case virtsnd_ctl_msg_complete() will not be
166 * called, it is necessary to decrement the reference count.
167 */
168 virtsnd_ctl_msg_unref(msg);
169
170 goto on_exit;
171 }
172
173 if (notify)
174 virtqueue_notify(queue->vqueue);
175
176 if (nowait)
177 goto on_exit;
178
179 rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
180 if (rc <= 0) {
181 if (!rc) {
182 dev_err(&vdev->dev,
183 "control message (0x%08x) timeout\n",
184 le32_to_cpu(request->code));
185 rc = -ETIMEDOUT;
186 }
187
188 goto on_exit;
189 }
190
191 switch (le32_to_cpu(response->code)) {
192 case VIRTIO_SND_S_OK:
193 rc = 0;
194 break;
195 case VIRTIO_SND_S_NOT_SUPP:
196 rc = -EOPNOTSUPP;
197 break;
198 case VIRTIO_SND_S_IO_ERR:
199 rc = -EIO;
200 break;
201 default:
202 rc = -EINVAL;
203 break;
204 }
205
206 on_exit:
207 virtsnd_ctl_msg_unref(msg);
208
209 return rc;
210 }
211
212 /**
213 * virtsnd_ctl_msg_complete() - Complete a control message.
214 * @msg: Control message.
215 *
216 * Context: Any context. Expects the control queue spinlock to be held by
217 * caller.
218 */
219 void virtsnd_ctl_msg_complete(struct virtio_snd_msg *msg)
220 {
221 list_del(&msg->list);
222 complete(&msg->notify);
223
224 virtsnd_ctl_msg_unref(msg);
225 }
226
227 /**
228 * virtsnd_ctl_msg_cancel_all() - Cancel all pending control messages.
229 * @snd: VirtIO sound device.
230 *
231 * Context: Any context.
232 */
233 void virtsnd_ctl_msg_cancel_all(struct virtio_snd *snd)
234 {
235 struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
236 unsigned long flags;
237
238 spin_lock_irqsave(&queue->lock, flags);
239 while (!list_empty(&snd->ctl_msgs)) {
240 struct virtio_snd_msg *msg =
241 list_first_entry(&snd->ctl_msgs, struct virtio_snd_msg,
242 list);
243
244 virtsnd_ctl_msg_complete(msg);
245 }
246 spin_unlock_irqrestore(&queue->lock, flags);
247 }
248
249 /**
250 * virtsnd_ctl_query_info() - Query the item configuration from the device.
251 * @snd: VirtIO sound device.
252 * @command: Control request code (VIRTIO_SND_R_XXX_INFO).
253 * @start_id: Item start identifier.
254 * @count: Item count to query.
255 * @size: Item information size in bytes.
256 * @info: Buffer for storing item information.
257 *
258 * Context: Any context that permits to sleep.
259 * Return: 0 on success, -errno on failure.
260 */
261 int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
262 int count, size_t size, void *info)
263 {
264 struct virtio_snd_msg *msg;
265 struct virtio_snd_query_info *query;
266 struct scatterlist sg;
267
268 msg = virtsnd_ctl_msg_alloc(sizeof(*query),
269 sizeof(struct virtio_snd_hdr), GFP_KERNEL);
270 if (!msg)
271 return -ENOMEM;
272
273 query = virtsnd_ctl_msg_request(msg);
274 query->hdr.code = cpu_to_le32(command);
275 query->start_id = cpu_to_le32(start_id);
276 query->count = cpu_to_le32(count);
277 query->size = cpu_to_le32(size);
278
279 sg_init_one(&sg, info, count * size);
280
281 return virtsnd_ctl_msg_send(snd, msg, NULL, &sg, false);
282 }
283
284 /**
285 * virtsnd_ctl_notify_cb() - Process all completed control messages.
286 * @vqueue: Underlying control virtqueue.
287 *
288 * This callback function is called upon a vring interrupt request from the
289 * device.
290 *
291 * Context: Interrupt context. Takes and releases the control queue spinlock.
292 */
293 void virtsnd_ctl_notify_cb(struct virtqueue *vqueue)
294 {
295 struct virtio_snd *snd = vqueue->vdev->priv;
296 struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
297 struct virtio_snd_msg *msg;
298 u32 length;
299 unsigned long flags;
300
301 spin_lock_irqsave(&queue->lock, flags);
302 do {
303 virtqueue_disable_cb(vqueue);
304 while ((msg = virtqueue_get_buf(vqueue, &length)))
305 virtsnd_ctl_msg_complete(msg);
306 } while (!virtqueue_enable_cb(vqueue));
307 spin_unlock_irqrestore(&queue->lock, flags);
308 }
309
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