The driver implements a message-based transport for I/O substream operations. Before the start of the substream, the hardware buffer is sliced into I/O messages, the number of which is equal to the current number of periods. The size of each message is equal to the current size of one period.
I/O messages are organized in an ordered queue. The completion of the I/O message indicates an elapsed period (the only exception is the end of the stream for the capture substream). Upon completion, the message is automatically re-added to the end of the queue.
Signed-off-by: Anton Yakovlev anton.yakovlev@opensynergy.com --- sound/virtio/Makefile | 3 +- sound/virtio/virtio_card.c | 18 +- sound/virtio/virtio_card.h | 9 + sound/virtio/virtio_pcm.c | 32 +++ sound/virtio/virtio_pcm.h | 42 ++++ sound/virtio/virtio_pcm_msg.c | 392 ++++++++++++++++++++++++++++++++++ 6 files changed, 493 insertions(+), 3 deletions(-) create mode 100644 sound/virtio/virtio_pcm_msg.c
diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile index 69162a545a41..626af3cc3ed7 100644 --- a/sound/virtio/Makefile +++ b/sound/virtio/Makefile @@ -5,5 +5,6 @@ obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o virtio_snd-objs := \ virtio_card.o \ virtio_ctl_msg.o \ - virtio_pcm.o + virtio_pcm.o \ + virtio_pcm_msg.o
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c index 235afc25fce7..a845978111d6 100644 --- a/sound/virtio/virtio_card.c +++ b/sound/virtio/virtio_card.c @@ -65,8 +65,16 @@ static void virtsnd_event_notify_cb(struct virtqueue *vqueue) spin_lock_irqsave(&queue->lock, flags); do { virtqueue_disable_cb(vqueue); - while ((event = virtqueue_get_buf(vqueue, &length))) + while ((event = virtqueue_get_buf(vqueue, &length))) { + switch (le32_to_cpu(event->hdr.code)) { + case VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED: + case VIRTIO_SND_EVT_PCM_XRUN: + virtsnd_pcm_event(snd, event); + break; + } + virtsnd_event_send(vqueue, event, true, GFP_ATOMIC); + } if (unlikely(virtqueue_is_broken(vqueue))) break; } while (!virtqueue_enable_cb(vqueue)); @@ -87,7 +95,9 @@ static int virtsnd_find_vqs(struct virtio_snd *snd) struct virtio_device *vdev = snd->vdev; vq_callback_t *callbacks[VIRTIO_SND_VQ_MAX] = { [VIRTIO_SND_VQ_CONTROL] = virtsnd_ctl_notify_cb, - [VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb + [VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb, + [VIRTIO_SND_VQ_TX] = virtsnd_pcm_tx_notify_cb, + [VIRTIO_SND_VQ_RX] = virtsnd_pcm_rx_notify_cb }; const char *names[VIRTIO_SND_VQ_MAX] = { [VIRTIO_SND_VQ_CONTROL] = "virtsnd-ctl", @@ -299,6 +309,7 @@ static int virtsnd_probe(struct virtio_device *vdev) static void virtsnd_remove(struct virtio_device *vdev) { struct virtio_snd *snd = vdev->priv; + unsigned int i;
/* Stop all the virtqueues. */ vdev->config->reset(vdev); @@ -310,6 +321,9 @@ static void virtsnd_remove(struct virtio_device *vdev)
vdev->config->del_vqs(vdev);
+ for (i = 0; snd->substreams && i < snd->nsubstreams; ++i) + virtsnd_pcm_msg_free(&snd->substreams[i]); + kfree(snd->event_msgs); }
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h index 687d3ed6d1c3..aca87059564e 100644 --- a/sound/virtio/virtio_card.h +++ b/sound/virtio/virtio_card.h @@ -81,4 +81,13 @@ virtsnd_rx_queue(struct virtio_snd *snd) return &snd->queues[VIRTIO_SND_VQ_RX]; }
+static inline struct virtio_snd_queue * +virtsnd_pcm_queue(struct virtio_pcm_substream *vss) +{ + if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK) + return virtsnd_tx_queue(vss->snd); + else + return virtsnd_rx_queue(vss->snd); +} + #endif /* VIRTIO_SND_CARD_H */ diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c index 9c2cf9eaa0c7..c88258f6a521 100644 --- a/sound/virtio/virtio_pcm.c +++ b/sound/virtio/virtio_pcm.c @@ -338,6 +338,8 @@ int virtsnd_pcm_parse_cfg(struct virtio_snd *snd)
vss->snd = snd; vss->sid = i; + init_waitqueue_head(&vss->msg_empty); + spin_lock_init(&vss->lock);
rc = virtsnd_pcm_build_hw(vss, &info[i]); if (rc) @@ -462,3 +464,33 @@ int virtsnd_pcm_build_devs(struct virtio_snd *snd)
return 0; } + +/** + * virtsnd_pcm_event() - Handle the PCM device event notification. + * @snd: VirtIO sound device. + * @event: VirtIO sound event. + * + * Context: Interrupt context. + */ +void virtsnd_pcm_event(struct virtio_snd *snd, struct virtio_snd_event *event) +{ + struct virtio_pcm_substream *vss; + unsigned int sid = le32_to_cpu(event->data); + + if (sid >= snd->nsubstreams) + return; + + vss = &snd->substreams[sid]; + + switch (le32_to_cpu(event->hdr.code)) { + case VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED: + /* TODO: deal with shmem elapsed period */ + break; + case VIRTIO_SND_EVT_PCM_XRUN: + spin_lock(&vss->lock); + if (vss->xfer_enabled) + vss->xfer_xrun = true; + spin_unlock(&vss->lock); + break; + } +} diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h index 42d592da41e5..d6be62b52421 100644 --- a/sound/virtio/virtio_pcm.h +++ b/sound/virtio/virtio_pcm.h @@ -22,6 +22,19 @@ struct virtio_pcm_msg; * @features: Stream VirtIO feature bit map (1 << VIRTIO_SND_PCM_F_XXX). * @substream: Kernel ALSA substream. * @hw: Kernel ALSA substream hardware descriptor. + * @frame_bytes: Current frame size in bytes. + * @period_size: Current period size in frames. + * @buffer_size: Current buffer size in frames. + * @lock: Spinlock that protects fields shared by interrupt handlers and + * substream operators. + * @hw_ptr: Substream hardware pointer value in frames [0 ... buffer_size). + * @xfer_enabled: Data transfer state (0 - off, 1 - on). + * @xfer_xrun: Data underflow/overflow state (0 - no xrun, 1 - xrun). + * @msgs: Allocated I/O messages. + * @nmsgs: Number of allocated I/O messages. + * @msg_last_enqueued: Index of the last I/O message added to the virtqueue. + * @msg_count: Number of pending I/O messages in the virtqueue. + * @msg_empty: Notify when msg_count is zero. */ struct virtio_pcm_substream { struct virtio_snd *snd; @@ -31,6 +44,18 @@ struct virtio_pcm_substream { u32 features; struct snd_pcm_substream *substream; struct snd_pcm_hardware hw; + unsigned int frame_bytes; + snd_pcm_uframes_t period_size; + snd_pcm_uframes_t buffer_size; + spinlock_t lock; + snd_pcm_uframes_t hw_ptr; + bool xfer_enabled; + bool xfer_xrun; + struct virtio_pcm_msg **msgs; + unsigned int nmsgs; + int msg_last_enqueued; + unsigned int msg_count; + wait_queue_head_t msg_empty; };
/** @@ -63,9 +88,26 @@ int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
int virtsnd_pcm_build_devs(struct virtio_snd *snd);
+void virtsnd_pcm_event(struct virtio_snd *snd, struct virtio_snd_event *event); + +void virtsnd_pcm_tx_notify_cb(struct virtqueue *vqueue); + +void virtsnd_pcm_rx_notify_cb(struct virtqueue *vqueue); + struct virtio_pcm *virtsnd_pcm_find(struct virtio_snd *snd, unsigned int nid);
struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, unsigned int nid);
+struct virtio_snd_msg * +virtsnd_pcm_ctl_msg_alloc(struct virtio_pcm_substream *vss, + unsigned int command, gfp_t gfp); + +int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss, + unsigned int periods, unsigned int period_bytes); + +void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss); + +int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss); + #endif /* VIRTIO_SND_PCM_H */ diff --git a/sound/virtio/virtio_pcm_msg.c b/sound/virtio/virtio_pcm_msg.c new file mode 100644 index 000000000000..8f29a9baf806 --- /dev/null +++ b/sound/virtio/virtio_pcm_msg.c @@ -0,0 +1,392 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * virtio-snd: Virtio sound device + * Copyright (C) 2021 OpenSynergy GmbH + */ +#include <sound/pcm_params.h> + +#include "virtio_card.h" + +/** + * struct virtio_pcm_msg - VirtIO I/O message. + * @substream: VirtIO PCM substream. + * @xfer: Request header payload. + * @status: Response header payload. + * @sgs: Payload scatter-gather table. + */ +struct virtio_pcm_msg { + struct virtio_pcm_substream *substream; + struct virtio_snd_pcm_xfer xfer; + struct virtio_snd_pcm_status status; + struct scatterlist sgs[0]; +}; + +/** + * enum pcm_msg_sg_index - Index values for the virtio_pcm_msg->sgs field in + * an I/O message. + * @PCM_MSG_SG_XFER: Element containing a virtio_snd_pcm_xfer structure. + * @PCM_MSG_SG_STATUS: Element containing a virtio_snd_pcm_status structure. + * @PCM_MSG_SG_DATA: The first element containing a data buffer. + */ +enum pcm_msg_sg_index { + PCM_MSG_SG_XFER = 0, + PCM_MSG_SG_STATUS, + PCM_MSG_SG_DATA +}; + +/** + * virtsnd_pcm_sg_num() - Count the number of sg-elements required to represent + * vmalloc'ed buffer. + * @data: Pointer to vmalloc'ed buffer. + * @length: Buffer size. + * + * Context: Any context. + * Return: Number of physically contiguous parts in the @data. + */ +static int virtsnd_pcm_sg_num(u8 *data, unsigned int length) +{ + phys_addr_t sg_address; + unsigned int sg_length; + int num = 0; + + while (length) { + struct page *pg = vmalloc_to_page(data); + phys_addr_t pg_address = page_to_phys(pg); + size_t pg_length; + + pg_length = PAGE_SIZE - offset_in_page(data); + if (pg_length > length) + pg_length = length; + + if (!num || sg_address + sg_length != pg_address) { + sg_address = pg_address; + sg_length = pg_length; + num++; + } else { + sg_length += pg_length; + } + + data += pg_length; + length -= pg_length; + } + + return num; +} + +/** + * virtsnd_pcm_sg_from() - Build sg-list from vmalloc'ed buffer. + * @sgs: Preallocated sg-list to populate. + * @nsgs: The maximum number of elements in the @sgs. + * @data: Pointer to vmalloc'ed buffer. + * @length: Buffer size. + * + * Splits the buffer into physically contiguous parts and makes an sg-list of + * such parts. + * + * Context: Any context. + */ +static void virtsnd_pcm_sg_from(struct scatterlist *sgs, int nsgs, u8 *data, + unsigned int length) +{ + int idx = -1; + + while (length) { + struct page *pg = vmalloc_to_page(data); + size_t pg_length; + + pg_length = PAGE_SIZE - offset_in_page(data); + if (pg_length > length) + pg_length = length; + + if (idx == -1 || + sg_phys(&sgs[idx]) + sgs[idx].length != page_to_phys(pg)) { + if (idx + 1 == nsgs) + break; + sg_set_page(&sgs[++idx], pg, pg_length, + offset_in_page(data)); + } else { + sgs[idx].length += pg_length; + } + + data += pg_length; + length -= pg_length; + } + + sg_mark_end(&sgs[idx]); +} + +/** + * virtsnd_pcm_msg_alloc() - Allocate I/O messages. + * @vss: VirtIO PCM substream. + * @periods: Current number of periods. + * @period_bytes: Current period size in bytes. + * + * The function slices the buffer into @periods parts (each with the size of + * @period_bytes), and creates @periods corresponding I/O messages. + * + * Context: Any context that permits to sleep. + * Return: 0 on success, -ENOMEM on failure. + */ +int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss, + unsigned int periods, unsigned int period_bytes) +{ + struct snd_pcm_runtime *runtime = vss->substream->runtime; + unsigned int i; + + /* Free previously allocated messages (if any). */ + virtsnd_pcm_msg_free(vss); + + vss->msgs = kcalloc(periods, sizeof(*vss->msgs), GFP_KERNEL); + if (!vss->msgs) + return -ENOMEM; + + vss->nmsgs = periods; + + for (i = 0; i < periods; ++i) { + u8 *data = runtime->dma_area + period_bytes * i; + int sg_num = virtsnd_pcm_sg_num(data, period_bytes); + struct virtio_pcm_msg *msg; + + msg = kzalloc(sizeof(*msg) + sizeof(*msg->sgs) * (sg_num + 2), + GFP_KERNEL); + if (!msg) + return -ENOMEM; + + msg->substream = vss; + sg_init_one(&msg->sgs[PCM_MSG_SG_XFER], &msg->xfer, + sizeof(msg->xfer)); + sg_init_one(&msg->sgs[PCM_MSG_SG_STATUS], &msg->status, + sizeof(msg->status)); + virtsnd_pcm_sg_from(&msg->sgs[PCM_MSG_SG_DATA], sg_num, data, + period_bytes); + + vss->msgs[i] = msg; + } + + return 0; +} + +/** + * virtsnd_pcm_msg_free() - Free all allocated I/O messages. + * @vss: VirtIO PCM substream. + * + * Context: Any context. + */ +void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss) +{ + unsigned int i; + + for (i = 0; i < vss->nmsgs; ++i) + kfree(vss->msgs[i]); + kfree(vss->msgs); + + vss->msgs = NULL; + vss->nmsgs = 0; +} + +/** + * virtsnd_pcm_msg_send() - Send asynchronous I/O messages. + * @vss: VirtIO PCM substream. + * + * All messages are organized in an ordered circular list. Each time the + * function is called, all currently non-enqueued messages are added to the + * virtqueue. For this, the function keeps track of two values: + * + * msg_last_enqueued = index of the last enqueued message, + * msg_count = # of pending messages in the virtqueue. + * + * Context: Any context. Expects the tx/rx queue and the VirtIO substream + * spinlocks to be held by caller. + * Return: 0 on success, -errno on failure. + */ +int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss) +{ + struct snd_pcm_runtime *runtime = vss->substream->runtime; + struct virtio_snd *snd = vss->snd; + struct virtio_device *vdev = snd->vdev; + struct virtqueue *vqueue = virtsnd_pcm_queue(vss)->vqueue; + int i; + int n; + bool notify = false; + + i = (vss->msg_last_enqueued + 1) % runtime->periods; + n = runtime->periods - vss->msg_count; + + for (; n; --n, i = (i + 1) % runtime->periods) { + struct virtio_pcm_msg *msg = vss->msgs[i]; + struct scatterlist *psgs[] = { + &msg->sgs[PCM_MSG_SG_XFER], + &msg->sgs[PCM_MSG_SG_DATA], + &msg->sgs[PCM_MSG_SG_STATUS] + }; + int rc; + + msg->xfer.stream_id = cpu_to_le32(vss->sid); + memset(&msg->status, 0, sizeof(msg->status)); + + if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK) + rc = virtqueue_add_sgs(vqueue, psgs, 2, 1, msg, + GFP_ATOMIC); + else + rc = virtqueue_add_sgs(vqueue, psgs, 1, 2, msg, + GFP_ATOMIC); + + if (rc) { + dev_err(&vdev->dev, + "SID %u: failed to send I/O message\n", + vss->sid); + return rc; + } + + vss->msg_last_enqueued = i; + vss->msg_count++; + } + + if (!(vss->features & (1U << VIRTIO_SND_PCM_F_MSG_POLLING))) + notify = virtqueue_kick_prepare(vqueue); + + if (notify) + virtqueue_notify(vqueue); + + return 0; +} + +/** + * virtsnd_pcm_msg_complete() - Complete an I/O message. + * @msg: I/O message. + * @size: Number of bytes written. + * + * Completion of the message means the elapsed period. + * + * Context: Interrupt context. Takes and releases the VirtIO substream spinlock. + */ +static void virtsnd_pcm_msg_complete(struct virtio_pcm_msg *msg, size_t size) +{ + struct virtio_pcm_substream *vss = msg->substream; + + /* + * hw_ptr always indicates the buffer position of the first I/O message + * in the virtqueue. Therefore, on each completion of an I/O message, + * the hw_ptr value is unconditionally advanced. + */ + spin_lock(&vss->lock); + /* + * If the capture substream returned an incorrect status, then just + * increase the hw_ptr by the period size. + */ + if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK || + size <= sizeof(msg->status)) { + vss->hw_ptr += vss->period_size; + } else { + size -= sizeof(msg->status); + vss->hw_ptr += size / vss->frame_bytes; + } + + vss->hw_ptr %= vss->buffer_size; + vss->xfer_xrun = false; + vss->msg_count--; + + if (vss->xfer_enabled) { + struct snd_pcm_runtime *runtime = vss->substream->runtime; + + runtime->delay = + bytes_to_frames(runtime, + le32_to_cpu(msg->status.latency_bytes)); + + spin_unlock(&vss->lock); + snd_pcm_period_elapsed(vss->substream); + spin_lock(&vss->lock); + + virtsnd_pcm_msg_send(vss); + } else if (!vss->msg_count) { + wake_up_all(&vss->msg_empty); + } + spin_unlock(&vss->lock); +} + +/** + * virtsnd_pcm_notify_cb() - Process all completed I/O messages. + * @queue: Underlying tx/rx virtqueue. + * + * If transmission is allowed, then each completed message is immediately placed + * back at the end of the queue. + * + * Context: Interrupt context. Takes and releases the tx/rx queue spinlock. + */ +static inline void virtsnd_pcm_notify_cb(struct virtio_snd_queue *queue) +{ + struct virtio_pcm_msg *msg; + u32 length; + unsigned long flags; + + spin_lock_irqsave(&queue->lock, flags); + do { + virtqueue_disable_cb(queue->vqueue); + while ((msg = virtqueue_get_buf(queue->vqueue, &length))) + virtsnd_pcm_msg_complete(msg, length); + if (unlikely(virtqueue_is_broken(queue->vqueue))) + break; + } while (!virtqueue_enable_cb(queue->vqueue)); + spin_unlock_irqrestore(&queue->lock, flags); +} + +/** + * virtsnd_pcm_tx_notify_cb() - Process all completed TX messages. + * @vqueue: Underlying tx virtqueue. + * + * Context: Interrupt context. + */ +void virtsnd_pcm_tx_notify_cb(struct virtqueue *vqueue) +{ + struct virtio_snd *snd = vqueue->vdev->priv; + + virtsnd_pcm_notify_cb(virtsnd_tx_queue(snd)); +} + +/** + * virtsnd_pcm_rx_notify_cb() - Process all completed RX messages. + * @vqueue: Underlying rx virtqueue. + * + * Context: Interrupt context. + */ +void virtsnd_pcm_rx_notify_cb(struct virtqueue *vqueue) +{ + struct virtio_snd *snd = vqueue->vdev->priv; + + virtsnd_pcm_notify_cb(virtsnd_rx_queue(snd)); +} + +/** + * virtsnd_pcm_ctl_msg_alloc() - Allocate and initialize the PCM device control + * message for the specified substream. + * @vss: VirtIO PCM substream. + * @command: Control request code (VIRTIO_SND_R_PCM_XXX). + * @gfp: Kernel flags for memory allocation. + * + * Context: Any context. May sleep if @gfp flags permit. + * Return: Allocated message on success, NULL on failure. + */ +struct virtio_snd_msg * +virtsnd_pcm_ctl_msg_alloc(struct virtio_pcm_substream *vss, + unsigned int command, gfp_t gfp) +{ + size_t request_size = sizeof(struct virtio_snd_pcm_hdr); + size_t response_size = sizeof(struct virtio_snd_hdr); + struct virtio_snd_msg *msg; + + switch (command) { + case VIRTIO_SND_R_PCM_SET_PARAMS: + request_size = sizeof(struct virtio_snd_pcm_set_params); + break; + } + + msg = virtsnd_ctl_msg_alloc(request_size, response_size, gfp); + if (msg) { + struct virtio_snd_pcm_hdr *hdr = virtsnd_ctl_msg_request(msg); + + hdr->hdr.code = cpu_to_le32(command); + hdr->stream_id = cpu_to_le32(vss->sid); + } + + return msg; +}