virtio_ctl_msg.c

  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	int rc;
135
136	virtsnd_ctl_msg_ref(msg);
137
138	/* Set the default status in case the message was canceled. */
139	response->code = cpu_to_le32(VIRTIO_SND_S_IO_ERR);
140
141	psgs[nouts++] = &msg->sg_request;
142	if (out_sgs)
143		psgs[nouts++] = out_sgs;
144
145	psgs[nouts + nins++] = &msg->sg_response;
146	if (in_sgs)
147		psgs[nouts + nins++] = in_sgs;
148
149	scoped_guard(spinlock_irqsave, &queue->lock) {
150		rc = virtqueue_add_sgs(queue->vqueue, psgs, nouts, nins, msg,
151				       GFP_ATOMIC);
152		if (!rc) {
153			notify = virtqueue_kick_prepare(queue->vqueue);
154
155			list_add_tail(&msg->list, &snd->ctl_msgs);
156		}
157	}
158
159	if (rc) {
160		dev_err(&vdev->dev, "failed to send control message (0x%08x)\n",
161			le32_to_cpu(request->code));
162
163		/*
164		 * Since in this case virtsnd_ctl_msg_complete() will not be
165		 * called, it is necessary to decrement the reference count.
166		 */
167		virtsnd_ctl_msg_unref(msg);
168
169		goto on_exit;
170	}
171
172	if (notify)
173		virtqueue_notify(queue->vqueue);
174
175	if (nowait)
176		goto on_exit;
177
178	rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
179	if (rc <= 0) {
180		if (!rc) {
181			dev_err(&vdev->dev,
182				"control message (0x%08x) timeout\n",
183				le32_to_cpu(request->code));
184			rc = -ETIMEDOUT;
185		}
186
187		goto on_exit;
188	}
189
190	switch (le32_to_cpu(response->code)) {
191	case VIRTIO_SND_S_OK:
192		rc = 0;
193		break;
194	case VIRTIO_SND_S_NOT_SUPP:
195		rc = -EOPNOTSUPP;
196		break;
197	case VIRTIO_SND_S_IO_ERR:
198		rc = -EIO;
199		break;
200	default:
201		rc = -EINVAL;
202		break;
203	}
204
205on_exit:
206	virtsnd_ctl_msg_unref(msg);
207
208	return rc;
209}
210
211/**
212 * virtsnd_ctl_msg_complete() - Complete a control message.
213 * @msg: Control message.
214 *
215 * Context: Any context. Expects the control queue spinlock to be held by
216 *          caller.
217 */
218void virtsnd_ctl_msg_complete(struct virtio_snd_msg *msg)
219{
220	list_del(&msg->list);
221	complete(&msg->notify);
222
223	virtsnd_ctl_msg_unref(msg);
224}
225
226/**
227 * virtsnd_ctl_msg_cancel_all() - Cancel all pending control messages.
228 * @snd: VirtIO sound device.
229 *
230 * Context: Any context.
231 */
232void virtsnd_ctl_msg_cancel_all(struct virtio_snd *snd)
233{
234	struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
235
236	guard(spinlock_irqsave)(&queue->lock);
237	while (!list_empty(&snd->ctl_msgs)) {
238		struct virtio_snd_msg *msg =
239			list_first_entry(&snd->ctl_msgs, struct virtio_snd_msg,
240					 list);
241
242		virtsnd_ctl_msg_complete(msg);
243	}
244}
245
246/**
247 * virtsnd_ctl_query_info() - Query the item configuration from the device.
248 * @snd: VirtIO sound device.
249 * @command: Control request code (VIRTIO_SND_R_XXX_INFO).
250 * @start_id: Item start identifier.
251 * @count: Item count to query.
252 * @size: Item information size in bytes.
253 * @info: Buffer for storing item information.
254 *
255 * Context: Any context that permits to sleep.
256 * Return: 0 on success, -errno on failure.
257 */
258int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
259			   int count, size_t size, void *info)
260{
261	struct virtio_snd_msg *msg;
262	struct virtio_snd_query_info *query;
263	struct scatterlist sg;
264
265	msg = virtsnd_ctl_msg_alloc(sizeof(*query),
266				    sizeof(struct virtio_snd_hdr), GFP_KERNEL);
267	if (!msg)
268		return -ENOMEM;
269
270	query = virtsnd_ctl_msg_request(msg);
271	query->hdr.code = cpu_to_le32(command);
272	query->start_id = cpu_to_le32(start_id);
273	query->count = cpu_to_le32(count);
274	query->size = cpu_to_le32(size);
275
276	sg_init_one(&sg, info, count * size);
277
278	return virtsnd_ctl_msg_send(snd, msg, NULL, &sg, false);
279}
280
281/**
282 * virtsnd_ctl_notify_cb() - Process all completed control messages.
283 * @vqueue: Underlying control virtqueue.
284 *
285 * This callback function is called upon a vring interrupt request from the
286 * device.
287 *
288 * Context: Interrupt context. Takes and releases the control queue spinlock.
289 */
290void virtsnd_ctl_notify_cb(struct virtqueue *vqueue)
291{
292	struct virtio_snd *snd = vqueue->vdev->priv;
293	struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
294	struct virtio_snd_msg *msg;
295	u32 length;
296
297	guard(spinlock_irqsave)(&queue->lock);
298	do {
299		virtqueue_disable_cb(vqueue);
300		while ((msg = virtqueue_get_buf(vqueue, &length)))
301			virtsnd_ctl_msg_complete(msg);
302	} while (!virtqueue_enable_cb(vqueue));
303}