[PATCH 5/7] ALSA: virtio: PCM substream operators
Michael S. Tsirkin
mst at redhat.com
Wed Jan 20 09:36:42 CET 2021
On Wed, Jan 20, 2021 at 01:36:33AM +0100, Anton Yakovlev wrote:
> Introduce the operators required for the operation of substreams.
>
> Signed-off-by: Anton Yakovlev <anton.yakovlev at opensynergy.com>
> ---
> sound/virtio/Makefile | 3 +-
> sound/virtio/virtio_pcm.c | 5 +-
> sound/virtio/virtio_pcm.h | 2 +
> sound/virtio/virtio_pcm_ops.c | 509 ++++++++++++++++++++++++++++++++++
> 4 files changed, 517 insertions(+), 2 deletions(-)
> create mode 100644 sound/virtio/virtio_pcm_ops.c
>
> diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
> index 626af3cc3ed7..34493226793f 100644
> --- a/sound/virtio/Makefile
> +++ b/sound/virtio/Makefile
> @@ -6,5 +6,6 @@ virtio_snd-objs := \
> virtio_card.o \
> virtio_ctl_msg.o \
> virtio_pcm.o \
> - virtio_pcm_msg.o
> + virtio_pcm_msg.o \
> + virtio_pcm_ops.o
>
> diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
> index 1ab50dcc88c8..6a1ca6b2c3ca 100644
> --- a/sound/virtio/virtio_pcm.c
> +++ b/sound/virtio/virtio_pcm.c
> @@ -121,7 +121,8 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *substream,
> SNDRV_PCM_INFO_MMAP_VALID |
> SNDRV_PCM_INFO_BATCH |
> SNDRV_PCM_INFO_BLOCK_TRANSFER |
> - SNDRV_PCM_INFO_INTERLEAVED;
> + SNDRV_PCM_INFO_INTERLEAVED |
> + SNDRV_PCM_INFO_PAUSE;
>
> if (!info->channels_min || info->channels_min > info->channels_max) {
> dev_err(&vdev->dev,
> @@ -503,6 +504,8 @@ int virtsnd_pcm_build_devs(struct virtio_snd *snd)
> if (rc)
> return rc;
> }
> +
> + snd_pcm_set_ops(pcm->pcm, i, &virtsnd_pcm_ops);
> }
>
> return 0;
> diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
> index d011b7e1d18d..fe467bc05d8b 100644
> --- a/sound/virtio/virtio_pcm.h
> +++ b/sound/virtio/virtio_pcm.h
> @@ -90,6 +90,8 @@ struct virtio_pcm {
> struct virtio_pcm_stream streams[SNDRV_PCM_STREAM_LAST + 1];
> };
>
> +extern const struct snd_pcm_ops virtsnd_pcm_ops;
> +
> int virtsnd_pcm_validate(struct virtio_device *vdev);
>
> int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
> diff --git a/sound/virtio/virtio_pcm_ops.c b/sound/virtio/virtio_pcm_ops.c
> new file mode 100644
> index 000000000000..8d26c1144ad6
> --- /dev/null
> +++ b/sound/virtio/virtio_pcm_ops.c
> @@ -0,0 +1,509 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Sound card driver for virtio
> + * Copyright (C) 2020 OpenSynergy GmbH
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + */
> +#include <sound/pcm_params.h>
> +
> +#include "virtio_card.h"
> +
> +/*
> + * Our main concern here is maintaining the correct state of the underlying I/O
> + * virtqueues. Thus, operators are implemented to support all of the following
> + * possible control paths (excluding all trivial ones):
> + *
> + * +---------+
> + * | open() |<------------------+
> + * +----+----+ |
> + * v |
> + * +------+------+ |
> + * +------------->| hw_params() |<-------------+ |
> + * | +-------------+ | |
> + * | v | |
> + * | +-----------+ | |
> + * | | prepare() |<-----------+ | |
> + * | +-----------+ | | |
> + * | v | | |
> + * | +-------------------------+ | | |
> + * +-----------+ | trigger(START/ | | | |
> + * | restore() | | PAUSE_RELEASE/ |<-+ | | |
> + * +-----------+ | RESUME) | | | | |
> + * ^ +-------------------------+ | | | |
> + * | v | | | |
> + * | +-----------+ | | | |
> + * | | pointer() | | | | |
> + * | +-----------+ | | | |
> + * | v | | | |
> + * | +---------------------+ | | | |
> + * +-----------+ | trigger(STOP/ |----+ | | |
> + * | freeze() |<---| PAUSE_PUSH/ |-------+ | |
> + * +-----------+ | SUSPEND) | | |
> + * +---------------------+ | |
> + * v | |
> + * +-----------+ | |
> + * | hw_free() |---------------+ |
> + * +-----------+ |
> + * v |
> + * +---------+ |
> + * | close() |-------------------+
> + * +---------+
> + */
> +
> +/* Map for converting ALSA format to VirtIO format. */
> +struct virtsnd_a2v_format {
> + unsigned int alsa_bit;
> + unsigned int vio_bit;
> +};
> +
> +static const struct virtsnd_a2v_format g_a2v_format_map[] = {
> + { SNDRV_PCM_FORMAT_IMA_ADPCM, VIRTIO_SND_PCM_FMT_IMA_ADPCM },
> + { SNDRV_PCM_FORMAT_MU_LAW, VIRTIO_SND_PCM_FMT_MU_LAW },
> + { SNDRV_PCM_FORMAT_A_LAW, VIRTIO_SND_PCM_FMT_A_LAW },
> + { SNDRV_PCM_FORMAT_S8, VIRTIO_SND_PCM_FMT_S8 },
> + { SNDRV_PCM_FORMAT_U8, VIRTIO_SND_PCM_FMT_U8 },
> + { SNDRV_PCM_FORMAT_S16_LE, VIRTIO_SND_PCM_FMT_S16 },
> + { SNDRV_PCM_FORMAT_U16_LE, VIRTIO_SND_PCM_FMT_U16 },
> + { SNDRV_PCM_FORMAT_S18_3LE, VIRTIO_SND_PCM_FMT_S18_3 },
> + { SNDRV_PCM_FORMAT_U18_3LE, VIRTIO_SND_PCM_FMT_U18_3 },
> + { SNDRV_PCM_FORMAT_S20_3LE, VIRTIO_SND_PCM_FMT_S20_3 },
> + { SNDRV_PCM_FORMAT_U20_3LE, VIRTIO_SND_PCM_FMT_U20_3 },
> + { SNDRV_PCM_FORMAT_S24_3LE, VIRTIO_SND_PCM_FMT_S24_3 },
> + { SNDRV_PCM_FORMAT_U24_3LE, VIRTIO_SND_PCM_FMT_U24_3 },
> + { SNDRV_PCM_FORMAT_S20_LE, VIRTIO_SND_PCM_FMT_S20 },
> + { SNDRV_PCM_FORMAT_U20_LE, VIRTIO_SND_PCM_FMT_U20 },
> + { SNDRV_PCM_FORMAT_S24_LE, VIRTIO_SND_PCM_FMT_S24 },
> + { SNDRV_PCM_FORMAT_U24_LE, VIRTIO_SND_PCM_FMT_U24 },
> + { SNDRV_PCM_FORMAT_S32_LE, VIRTIO_SND_PCM_FMT_S32 },
> + { SNDRV_PCM_FORMAT_U32_LE, VIRTIO_SND_PCM_FMT_U32 },
> + { SNDRV_PCM_FORMAT_FLOAT_LE, VIRTIO_SND_PCM_FMT_FLOAT },
> + { SNDRV_PCM_FORMAT_FLOAT64_LE, VIRTIO_SND_PCM_FMT_FLOAT64 },
> + { SNDRV_PCM_FORMAT_DSD_U8, VIRTIO_SND_PCM_FMT_DSD_U8 },
> + { SNDRV_PCM_FORMAT_DSD_U16_LE, VIRTIO_SND_PCM_FMT_DSD_U16 },
> + { SNDRV_PCM_FORMAT_DSD_U32_LE, VIRTIO_SND_PCM_FMT_DSD_U32 },
> + { SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE,
> + VIRTIO_SND_PCM_FMT_IEC958_SUBFRAME }
> +};
> +
> +/* Map for converting ALSA frame rate to VirtIO frame rate. */
> +struct virtsnd_a2v_rate {
> + unsigned int rate;
> + unsigned int vio_bit;
> +};
> +
> +static const struct virtsnd_a2v_rate g_a2v_rate_map[] = {
> + { 5512, VIRTIO_SND_PCM_RATE_5512 },
> + { 8000, VIRTIO_SND_PCM_RATE_8000 },
> + { 11025, VIRTIO_SND_PCM_RATE_11025 },
> + { 16000, VIRTIO_SND_PCM_RATE_16000 },
> + { 22050, VIRTIO_SND_PCM_RATE_22050 },
> + { 32000, VIRTIO_SND_PCM_RATE_32000 },
> + { 44100, VIRTIO_SND_PCM_RATE_44100 },
> + { 48000, VIRTIO_SND_PCM_RATE_48000 },
> + { 64000, VIRTIO_SND_PCM_RATE_64000 },
> + { 88200, VIRTIO_SND_PCM_RATE_88200 },
> + { 96000, VIRTIO_SND_PCM_RATE_96000 },
> + { 176400, VIRTIO_SND_PCM_RATE_176400 },
> + { 192000, VIRTIO_SND_PCM_RATE_192000 }
> +};
> +
> +/**
> + * virtsnd_pcm_release() - Release the PCM substream on the device side.
> + * @substream: VirtIO substream.
> + *
> + * The function waits for all pending I/O messages to complete.
> + *
> + * Context: Any context that permits to sleep.
> + * Return: 0 on success, -errno on failure.
> + */
> +static inline bool virtsnd_pcm_released(struct virtio_pcm_substream *substream)
> +{
> + return atomic_read(&substream->msg_count) == 0;
All this use of atomic_read/atomic_set all over the place makes me pause.
Could you add documentation explaining the use rules for these atomic fields?
> +}
> +
> +static int virtsnd_pcm_release(struct virtio_pcm_substream *substream)
> +{
> + struct virtio_snd *snd = substream->snd;
> + struct virtio_snd_msg *msg;
> + unsigned int js = msecs_to_jiffies(msg_timeout_ms);
> + int rc;
> +
> + msg = virtsnd_pcm_ctl_msg_alloc(substream, VIRTIO_SND_R_PCM_RELEASE,
> + GFP_KERNEL);
> + if (IS_ERR(msg))
> + return PTR_ERR(msg);
> +
> + rc = virtsnd_ctl_msg_send_sync(snd, msg);
> + if (rc)
> + return rc;
> +
> + return wait_event_interruptible_timeout(substream->msg_empty,
> + virtsnd_pcm_released(substream),
> + js);
> +}
> +
> +/**
> + * virtsnd_pcm_open() - Open the PCM substream.
> + * @substream: Kernel ALSA substream.
> + *
> + * Context: Any context.
> + * Return: 0 on success, -errno on failure.
> + */
> +static int virtsnd_pcm_open(struct snd_pcm_substream *substream)
> +{
> + struct virtio_pcm *pcm = snd_pcm_substream_chip(substream);
> + struct virtio_pcm_substream *ss = NULL;
> +
> + if (pcm) {
> + switch (substream->stream) {
> + case SNDRV_PCM_STREAM_PLAYBACK:
> + case SNDRV_PCM_STREAM_CAPTURE: {
> + struct virtio_pcm_stream *stream =
> + &pcm->streams[substream->stream];
> +
> + if (substream->number < stream->nsubstreams)
> + ss = stream->substreams[substream->number];
> + break;
> + }
> + }
> + }
> +
> + if (!ss)
> + return -EBADFD;
> +
> + substream->runtime->hw = ss->hw;
> + substream->private_data = ss;
> +
> + return 0;
> +}
> +
> +/**
> + * virtsnd_pcm_close() - Close the PCM substream.
> + * @substream: Kernel ALSA substream.
> + *
> + * Context: Any context.
> + * Return: 0.
> + */
> +static int virtsnd_pcm_close(struct snd_pcm_substream *substream)
> +{
> + return 0;
> +}
> +
> +/**
> + * virtsnd_pcm_hw_params() - Set the parameters of the PCM substream.
> + * @substream: Kernel ALSA substream.
> + * @hw_params: Hardware parameters (can be NULL).
> + *
> + * The function can be called both from the upper level (in this case,
> + * @hw_params is not NULL) or from the driver itself (in this case, @hw_params
> + * is NULL, and the parameter values are taken from the runtime structure).
> + *
> + * In all cases, the function:
> + * 1. checks the state of the virtqueue and, if necessary, tries to fix it,
> + * 2. sets the parameters on the device side,
> + * 3. allocates a hardware buffer and I/O messages.
> + *
> + * Context: Any context that permits to sleep.
> + * Return: 0 on success, -errno on failure.
> + */
> +static int virtsnd_pcm_hw_params(struct snd_pcm_substream *substream,
> + struct snd_pcm_hw_params *hw_params)
> +{
> + struct snd_pcm_runtime *runtime = substream->runtime;
> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
> + struct virtio_device *vdev = ss->snd->vdev;
> + struct virtio_snd_msg *msg;
> + struct virtio_snd_pcm_set_params *request;
> + snd_pcm_format_t format;
> + unsigned int channels;
> + unsigned int rate;
> + unsigned int buffer_bytes;
> + unsigned int period_bytes;
> + unsigned int periods;
> + unsigned int i;
> + int vformat = -1;
> + int vrate = -1;
> + int rc;
> +
> + /*
> + * If we got here after ops->trigger() was called, the queue may
> + * still contain messages. In this case, we need to release the
> + * substream first.
> + */
> + if (atomic_read(&ss->msg_count)) {
> + rc = virtsnd_pcm_release(ss);
> + if (rc) {
> + dev_err(&vdev->dev,
> + "SID %u: invalid I/O queue state\n",
> + ss->sid);
> + return rc;
> + }
> + }
> +
> + /* Set hardware parameters in device */
> + if (hw_params) {
> + format = params_format(hw_params);
> + channels = params_channels(hw_params);
> + rate = params_rate(hw_params);
> + buffer_bytes = params_buffer_bytes(hw_params);
> + period_bytes = params_period_bytes(hw_params);
> + periods = params_periods(hw_params);
> + } else {
> + format = runtime->format;
> + channels = runtime->channels;
> + rate = runtime->rate;
> + buffer_bytes = frames_to_bytes(runtime, runtime->buffer_size);
> + period_bytes = frames_to_bytes(runtime, runtime->period_size);
> + periods = runtime->periods;
> + }
> +
> + for (i = 0; i < ARRAY_SIZE(g_a2v_format_map); ++i)
> + if (g_a2v_format_map[i].alsa_bit == format) {
> + vformat = g_a2v_format_map[i].vio_bit;
> +
> + break;
> + }
> +
> + for (i = 0; i < ARRAY_SIZE(g_a2v_rate_map); ++i)
> + if (g_a2v_rate_map[i].rate == rate) {
> + vrate = g_a2v_rate_map[i].vio_bit;
> +
> + break;
> + }
> +
> + if (vformat == -1 || vrate == -1)
> + return -EINVAL;
> +
> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_SET_PARAMS,
> + GFP_KERNEL);
> + if (IS_ERR(msg))
> + return PTR_ERR(msg);
> +
> + request = sg_virt(&msg->sg_request);
> +
> + request->buffer_bytes = cpu_to_virtio32(vdev, buffer_bytes);
> + request->period_bytes = cpu_to_virtio32(vdev, period_bytes);
> + request->channels = channels;
> + request->format = vformat;
> + request->rate = vrate;
> +
> + if (ss->features & (1U << VIRTIO_SND_PCM_F_MSG_POLLING))
> + request->features |=
> + cpu_to_virtio32(vdev,
> + 1U << VIRTIO_SND_PCM_F_MSG_POLLING);
> +
> + if (ss->features & (1U << VIRTIO_SND_PCM_F_EVT_XRUNS))
> + request->features |=
> + cpu_to_virtio32(vdev,
> + 1U << VIRTIO_SND_PCM_F_EVT_XRUNS);
> +
> + rc = virtsnd_ctl_msg_send_sync(ss->snd, msg);
> + if (rc)
> + return rc;
> +
> + /* If the buffer was already allocated earlier, do nothing. */
> + if (runtime->dma_area)
> + return 0;
> +
> + /* Allocate hardware buffer */
> + rc = snd_pcm_lib_malloc_pages(substream, buffer_bytes);
> + if (rc < 0)
> + return rc;
> +
> + /* Allocate and initialize I/O messages */
> + rc = virtsnd_pcm_msg_alloc(ss, periods, runtime->dma_area,
> + period_bytes);
> + if (rc)
> + snd_pcm_lib_free_pages(substream);
> +
> + return rc;
> +}
> +
> +/**
> + * virtsnd_pcm_hw_free() - Reset the parameters of the PCM substream.
> + * @substream: Kernel ALSA substream.
> + *
> + * The function does the following:
> + * 1. tries to release the PCM substream on the device side,
> + * 2. frees the hardware buffer.
> + *
> + * Context: Any context that permits to sleep.
> + * Return: 0 on success, -errno on failure.
> + */
> +static int virtsnd_pcm_hw_free(struct snd_pcm_substream *substream)
> +{
> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
> + int rc;
> +
> + rc = virtsnd_pcm_release(ss);
> +
> + /*
> + * Even if we failed to send the RELEASE message or wait for the queue
> + * flush to complete, we can safely delete the buffer. Because after
> + * receiving the STOP command, the device must stop all I/O message
> + * processing. If there are still pending messages in the queue, the
> + * next ops->hw_params() call should deal with this.
> + */
> + snd_pcm_lib_free_pages(substream);
> +
> + return rc;
> +}
> +
> +/**
> + * virtsnd_pcm_hw_params() - Prepare the PCM substream.
> + * @substream: Kernel ALSA substream.
> + *
> + * The function can be called both from the upper level or from the driver
> + * itself.
> + *
> + * In all cases, the function:
> + * 1. checks the state of the virtqueue and, if necessary, tries to fix it,
> + * 2. prepares the substream on the device side.
> + *
> + * Context: Any context that permits to sleep. May take and release the tx/rx
> + * queue spinlock.
> + * Return: 0 on success, -errno on failure.
> + */
> +static int virtsnd_pcm_prepare(struct snd_pcm_substream *substream)
> +{
> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
> + struct virtio_snd_queue *queue = virtsnd_pcm_queue(ss);
> + struct virtio_snd_msg *msg;
> + unsigned long flags;
> + int rc;
> +
> + /*
> + * If we got here after ops->trigger() was called, the queue may
> + * still contain messages. In this case, we need to reset the
> + * substream first.
> + */
> + if (atomic_read(&ss->msg_count)) {
> + rc = virtsnd_pcm_hw_params(substream, NULL);
> + if (rc)
> + return rc;
> + }
> +
> + spin_lock_irqsave(&queue->lock, flags);
> + ss->msg_last_enqueued = -1;
> + spin_unlock_irqrestore(&queue->lock, flags);
> +
> + /*
> + * Since I/O messages are asynchronous, they can be completed
> + * when the runtime structure no longer exists. Since each
> + * completion implies incrementing the hw_ptr, we cache all the
> + * current values needed to compute the new hw_ptr value.
> + */
> + ss->frame_bytes = substream->runtime->frame_bits >> 3;
> + ss->period_size = substream->runtime->period_size;
> + ss->buffer_size = substream->runtime->buffer_size;
> +
> + atomic_set(&ss->hw_ptr, 0);
> + atomic_set(&ss->xfer_xrun, 0);
> + atomic_set(&ss->msg_count, 0);
> +
> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_PREPARE,
> + GFP_KERNEL);
> + if (IS_ERR(msg))
> + return PTR_ERR(msg);
> +
> + return virtsnd_ctl_msg_send_sync(ss->snd, msg);
> +}
> +
> +/**
> + * virtsnd_pcm_trigger() - Process command for the PCM substream.
> + * @substream: Kernel ALSA substream.
> + * @command: Substream command (SNDRV_PCM_TRIGGER_XXX).
> + *
> + * Depending on the command, the function does the following:
> + * 1. enables/disables data transmission,
> + * 2. starts/stops the substream on the device side.
> + *
> + * Context: Atomic context. May take and release the tx/rx queue spinlock.
> + * Return: 0 on success, -errno on failure.
> + */
> +static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
> +{
> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
> + struct virtio_snd *snd = ss->snd;
> + struct virtio_snd_queue *queue = virtsnd_pcm_queue(ss);
> + struct virtio_snd_msg *msg;
> +
> + switch (command) {
> + case SNDRV_PCM_TRIGGER_START:
> + case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: {
> + int rc;
> +
> + spin_lock(&queue->lock);
> + rc = virtsnd_pcm_msg_send(ss);
> + spin_unlock(&queue->lock);
> + if (rc)
> + return rc;
> +
> + atomic_set(&ss->xfer_enabled, 1);
> +
> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_START,
> + GFP_ATOMIC);
> + if (IS_ERR(msg))
> + return PTR_ERR(msg);
> +
> + return virtsnd_ctl_msg_send(snd, msg);
> + }
> + case SNDRV_PCM_TRIGGER_STOP:
> + case SNDRV_PCM_TRIGGER_PAUSE_PUSH: {
> + atomic_set(&ss->xfer_enabled, 0);
> +
> + msg = virtsnd_pcm_ctl_msg_alloc(ss, VIRTIO_SND_R_PCM_STOP,
> + GFP_ATOMIC);
> + if (IS_ERR(msg))
> + return PTR_ERR(msg);
> +
> + return virtsnd_ctl_msg_send(snd, msg);
> + }
> + default: {
> + return -EINVAL;
> + }
> + }
> +}
> +
> +/**
> + * virtsnd_pcm_pointer() - Get the current hardware position for the PCM
> + * substream.
> + * @substream: Kernel ALSA substream.
> + *
> + * Context: Atomic context.
> + * Return: Hardware position in frames inside [0 ... buffer_size) range.
> + */
> +static snd_pcm_uframes_t
> +virtsnd_pcm_pointer(struct snd_pcm_substream *substream)
> +{
> + struct virtio_pcm_substream *ss = snd_pcm_substream_chip(substream);
> +
> + if (atomic_read(&ss->xfer_xrun))
> + return SNDRV_PCM_POS_XRUN;
> +
> + return (snd_pcm_uframes_t)atomic_read(&ss->hw_ptr);
> +}
> +
> +/* PCM substream operators map. */
> +const struct snd_pcm_ops virtsnd_pcm_ops = {
> + .open = virtsnd_pcm_open,
> + .close = virtsnd_pcm_close,
> + .ioctl = snd_pcm_lib_ioctl,
> + .hw_params = virtsnd_pcm_hw_params,
> + .hw_free = virtsnd_pcm_hw_free,
> + .prepare = virtsnd_pcm_prepare,
> + .trigger = virtsnd_pcm_trigger,
> + .pointer = virtsnd_pcm_pointer,
> +};
> --
> 2.30.0
>
>
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