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 */
19struct 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 */
33void 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 */
46void 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 */
58void *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 */
69void *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 */
85struct 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 */
121int 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
206on_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 */
219void 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 */
233void 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 */
261int 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 */
293void 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