1 // SPDX-License-Identifier: GPL-2.0+
3 * virtio-snd: Virtio sound device
4 * Copyright (C) 2021 OpenSynergy GmbH
6 #include <sound/pcm_params.h>
8 #include "virtio_card.h"
11 * struct virtio_pcm_msg - VirtIO I/O message.
12 * @substream: VirtIO PCM substream.
13 * @xfer: Request header payload.
14 * @status: Response header payload.
15 * @length: Data length in bytes.
16 * @sgs: Payload scatter-gather table.
18 struct virtio_pcm_msg {
19 struct virtio_pcm_substream *substream;
20 struct virtio_snd_pcm_xfer xfer;
21 struct virtio_snd_pcm_status status;
23 struct scatterlist sgs[];
27 * enum pcm_msg_sg_index - Index values for the virtio_pcm_msg->sgs field in
29 * @PCM_MSG_SG_XFER: Element containing a virtio_snd_pcm_xfer structure.
30 * @PCM_MSG_SG_STATUS: Element containing a virtio_snd_pcm_status structure.
31 * @PCM_MSG_SG_DATA: The first element containing a data buffer.
33 enum pcm_msg_sg_index {
40 * virtsnd_pcm_sg_num() - Count the number of sg-elements required to represent
42 * @data: Pointer to vmalloc'ed buffer.
43 * @length: Buffer size.
45 * Context: Any context.
46 * Return: Number of physically contiguous parts in the @data.
48 static int virtsnd_pcm_sg_num(u8 *data, unsigned int length)
50 phys_addr_t sg_address;
51 unsigned int sg_length;
55 struct page *pg = vmalloc_to_page(data);
56 phys_addr_t pg_address = page_to_phys(pg);
59 pg_length = PAGE_SIZE - offset_in_page(data);
60 if (pg_length > length)
63 if (!num || sg_address + sg_length != pg_address) {
64 sg_address = pg_address;
65 sg_length = pg_length;
68 sg_length += pg_length;
79 * virtsnd_pcm_sg_from() - Build sg-list from vmalloc'ed buffer.
80 * @sgs: Preallocated sg-list to populate.
81 * @nsgs: The maximum number of elements in the @sgs.
82 * @data: Pointer to vmalloc'ed buffer.
83 * @length: Buffer size.
85 * Splits the buffer into physically contiguous parts and makes an sg-list of
88 * Context: Any context.
90 static void virtsnd_pcm_sg_from(struct scatterlist *sgs, int nsgs, u8 *data,
96 struct page *pg = vmalloc_to_page(data);
99 pg_length = PAGE_SIZE - offset_in_page(data);
100 if (pg_length > length)
104 sg_phys(&sgs[idx]) + sgs[idx].length != page_to_phys(pg)) {
107 sg_set_page(&sgs[++idx], pg, pg_length,
108 offset_in_page(data));
110 sgs[idx].length += pg_length;
117 sg_mark_end(&sgs[idx]);
121 * virtsnd_pcm_msg_alloc() - Allocate I/O messages.
122 * @vss: VirtIO PCM substream.
123 * @periods: Current number of periods.
124 * @period_bytes: Current period size in bytes.
126 * The function slices the buffer into @periods parts (each with the size of
127 * @period_bytes), and creates @periods corresponding I/O messages.
129 * Context: Any context that permits to sleep.
130 * Return: 0 on success, -ENOMEM on failure.
132 int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss,
133 unsigned int periods, unsigned int period_bytes)
135 struct snd_pcm_runtime *runtime = vss->substream->runtime;
138 vss->msgs = kcalloc(periods, sizeof(*vss->msgs), GFP_KERNEL);
142 vss->nmsgs = periods;
144 for (i = 0; i < periods; ++i) {
145 u8 *data = runtime->dma_area + period_bytes * i;
146 int sg_num = virtsnd_pcm_sg_num(data, period_bytes);
147 struct virtio_pcm_msg *msg;
149 msg = kzalloc(struct_size(msg, sgs, sg_num + 2), GFP_KERNEL);
153 msg->substream = vss;
154 sg_init_one(&msg->sgs[PCM_MSG_SG_XFER], &msg->xfer,
156 sg_init_one(&msg->sgs[PCM_MSG_SG_STATUS], &msg->status,
157 sizeof(msg->status));
158 virtsnd_pcm_sg_from(&msg->sgs[PCM_MSG_SG_DATA], sg_num, data,
168 * virtsnd_pcm_msg_free() - Free all allocated I/O messages.
169 * @vss: VirtIO PCM substream.
171 * Context: Any context.
173 void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss)
177 for (i = 0; vss->msgs && i < vss->nmsgs; ++i)
186 * virtsnd_pcm_msg_send() - Send asynchronous I/O messages.
187 * @vss: VirtIO PCM substream.
188 * @offset: starting position that has been updated
189 * @bytes: number of bytes that has been updated
191 * All messages are organized in an ordered circular list. Each time the
192 * function is called, all currently non-enqueued messages are added to the
193 * virtqueue. For this, the function uses offset and bytes to calculate the
194 * messages that need to be added.
196 * Context: Any context. Expects the tx/rx queue and the VirtIO substream
197 * spinlocks to be held by caller.
198 * Return: 0 on success, -errno on failure.
200 int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss, unsigned long offset,
203 struct virtio_snd *snd = vss->snd;
204 struct virtio_device *vdev = snd->vdev;
205 struct virtqueue *vqueue = virtsnd_pcm_queue(vss)->vqueue;
206 unsigned long period_bytes = snd_pcm_lib_period_bytes(vss->substream);
207 unsigned long start, end, i;
208 unsigned int msg_count = vss->msg_count;
212 start = offset / period_bytes;
213 end = (offset + bytes - 1) / period_bytes;
215 for (i = start; i <= end; i++) {
216 struct virtio_pcm_msg *msg = vss->msgs[i];
217 struct scatterlist *psgs[] = {
218 &msg->sgs[PCM_MSG_SG_XFER],
219 &msg->sgs[PCM_MSG_SG_DATA],
220 &msg->sgs[PCM_MSG_SG_STATUS]
224 n = period_bytes - (offset % period_bytes);
229 if (msg->length == period_bytes) {
230 msg->xfer.stream_id = cpu_to_le32(vss->sid);
231 memset(&msg->status, 0, sizeof(msg->status));
233 if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK)
234 rc = virtqueue_add_sgs(vqueue, psgs, 2, 1, msg,
237 rc = virtqueue_add_sgs(vqueue, psgs, 1, 2, msg,
242 "SID %u: failed to send I/O message\n",
254 if (msg_count == vss->msg_count)
257 if (!(vss->features & (1U << VIRTIO_SND_PCM_F_MSG_POLLING)))
258 notify = virtqueue_kick_prepare(vqueue);
261 virtqueue_notify(vqueue);
267 * virtsnd_pcm_msg_pending_num() - Returns the number of pending I/O messages.
268 * @vss: VirtIO substream.
270 * Context: Any context.
271 * Return: Number of messages.
273 unsigned int virtsnd_pcm_msg_pending_num(struct virtio_pcm_substream *vss)
278 spin_lock_irqsave(&vss->lock, flags);
279 num = vss->msg_count;
280 spin_unlock_irqrestore(&vss->lock, flags);
286 * virtsnd_pcm_msg_complete() - Complete an I/O message.
288 * @written_bytes: Number of bytes written to the message.
290 * Completion of the message means the elapsed period. If transmission is
291 * allowed, then each completed message is immediately placed back at the end
294 * For the playback substream, @written_bytes is equal to sizeof(msg->status).
296 * For the capture substream, @written_bytes is equal to sizeof(msg->status)
297 * plus the number of captured bytes.
299 * Context: Interrupt context. Takes and releases the VirtIO substream spinlock.
301 static void virtsnd_pcm_msg_complete(struct virtio_pcm_msg *msg,
302 size_t written_bytes)
304 struct virtio_pcm_substream *vss = msg->substream;
307 * hw_ptr always indicates the buffer position of the first I/O message
308 * in the virtqueue. Therefore, on each completion of an I/O message,
309 * the hw_ptr value is unconditionally advanced.
311 spin_lock(&vss->lock);
313 * If the capture substream returned an incorrect status, then just
314 * increase the hw_ptr by the message size.
316 if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK ||
317 written_bytes <= sizeof(msg->status))
318 vss->hw_ptr += msg->length;
320 vss->hw_ptr += written_bytes - sizeof(msg->status);
322 if (vss->hw_ptr >= vss->buffer_bytes)
323 vss->hw_ptr -= vss->buffer_bytes;
327 vss->xfer_xrun = false;
330 if (vss->xfer_enabled) {
331 struct snd_pcm_runtime *runtime = vss->substream->runtime;
334 bytes_to_frames(runtime,
335 le32_to_cpu(msg->status.latency_bytes));
337 schedule_work(&vss->elapsed_period);
338 } else if (!vss->msg_count) {
339 wake_up_all(&vss->msg_empty);
341 spin_unlock(&vss->lock);
345 * virtsnd_pcm_notify_cb() - Process all completed I/O messages.
346 * @queue: Underlying tx/rx virtqueue.
348 * Context: Interrupt context. Takes and releases the tx/rx queue spinlock.
350 static inline void virtsnd_pcm_notify_cb(struct virtio_snd_queue *queue)
352 struct virtio_pcm_msg *msg;
356 spin_lock_irqsave(&queue->lock, flags);
358 virtqueue_disable_cb(queue->vqueue);
359 while ((msg = virtqueue_get_buf(queue->vqueue, &written_bytes)))
360 virtsnd_pcm_msg_complete(msg, written_bytes);
361 if (unlikely(virtqueue_is_broken(queue->vqueue)))
363 } while (!virtqueue_enable_cb(queue->vqueue));
364 spin_unlock_irqrestore(&queue->lock, flags);
368 * virtsnd_pcm_tx_notify_cb() - Process all completed TX messages.
369 * @vqueue: Underlying tx virtqueue.
371 * Context: Interrupt context.
373 void virtsnd_pcm_tx_notify_cb(struct virtqueue *vqueue)
375 struct virtio_snd *snd = vqueue->vdev->priv;
377 virtsnd_pcm_notify_cb(virtsnd_tx_queue(snd));
381 * virtsnd_pcm_rx_notify_cb() - Process all completed RX messages.
382 * @vqueue: Underlying rx virtqueue.
384 * Context: Interrupt context.
386 void virtsnd_pcm_rx_notify_cb(struct virtqueue *vqueue)
388 struct virtio_snd *snd = vqueue->vdev->priv;
390 virtsnd_pcm_notify_cb(virtsnd_rx_queue(snd));
394 * virtsnd_pcm_ctl_msg_alloc() - Allocate and initialize the PCM device control
395 * message for the specified substream.
396 * @vss: VirtIO PCM substream.
397 * @command: Control request code (VIRTIO_SND_R_PCM_XXX).
398 * @gfp: Kernel flags for memory allocation.
400 * Context: Any context. May sleep if @gfp flags permit.
401 * Return: Allocated message on success, NULL on failure.
403 struct virtio_snd_msg *
404 virtsnd_pcm_ctl_msg_alloc(struct virtio_pcm_substream *vss,
405 unsigned int command, gfp_t gfp)
407 size_t request_size = sizeof(struct virtio_snd_pcm_hdr);
408 size_t response_size = sizeof(struct virtio_snd_hdr);
409 struct virtio_snd_msg *msg;
412 case VIRTIO_SND_R_PCM_SET_PARAMS:
413 request_size = sizeof(struct virtio_snd_pcm_set_params);
417 msg = virtsnd_ctl_msg_alloc(request_size, response_size, gfp);
419 struct virtio_snd_pcm_hdr *hdr = virtsnd_ctl_msg_request(msg);
421 hdr->hdr.code = cpu_to_le32(command);
422 hdr->stream_id = cpu_to_le32(vss->sid);