Commit f40a2867 authored by Anton Yakovlev's avatar Anton Yakovlev Committed by Takashi Iwai
Browse files

ALSA: virtio: handling control and I/O messages for the PCM device 



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: default avatarAnton Yakovlev <anton.yakovlev@opensynergy.com>
Link: https://lore.kernel.org/r/20210302164709.3142702-6-anton.yakovlev@opensynergy.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 29b96bf5

sound/virtio/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -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

sound/virtio/virtio_card.c

+18 −4
Original line number Diff line number Diff line
@@ -55,6 +55,12 @@ static void virtsnd_event_send(struct virtqueue *vqueue, 
static void virtsnd_event_dispatch(struct virtio_snd *snd,

				   struct virtio_snd_event *event)

{

	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;

	}

}



/**
@@ -101,11 +107,15 @@ static int virtsnd_find_vqs(struct virtio_snd *snd) 
	struct virtio_device *vdev = snd->vdev;

	static 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

	};

	static const char *names[VIRTIO_SND_VQ_MAX] = {

		[VIRTIO_SND_VQ_CONTROL] = "virtsnd-ctl",

		[VIRTIO_SND_VQ_EVENT] = "virtsnd-event"

		[VIRTIO_SND_VQ_EVENT] = "virtsnd-event",

		[VIRTIO_SND_VQ_TX] = "virtsnd-tx",

		[VIRTIO_SND_VQ_RX] = "virtsnd-rx"

	};

	struct virtqueue *vqs[VIRTIO_SND_VQ_MAX] = { 0 };

	unsigned int i;
@@ -318,8 +328,12 @@ static void virtsnd_remove(struct virtio_device *vdev) 
	vdev->config->del_vqs(vdev);

	vdev->config->reset(vdev);



	for (i = 0; snd->substreams && i < snd->nsubstreams; ++i)

		cancel_work_sync(&snd->substreams[i].elapsed_period);

	for (i = 0; snd->substreams && i < snd->nsubstreams; ++i) {

		struct virtio_pcm_substream *vss = &snd->substreams[i];



		cancel_work_sync(&vss->elapsed_period);

		virtsnd_pcm_msg_free(vss);

	}



	kfree(snd->event_msgs);

}

sound/virtio/virtio_card.h

+9 −0
Original line number Diff line number Diff line
@@ -79,4 +79,13 @@ 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 */

sound/virtio/virtio_pcm.c

+32 −0
Original line number Diff line number Diff line
@@ -353,6 +353,8 @@ int virtsnd_pcm_parse_cfg(struct virtio_snd *snd) 
		vss->snd = snd;

		vss->sid = i;

		INIT_WORK(&vss->elapsed_period, virtsnd_pcm_period_elapsed);

		init_waitqueue_head(&vss->msg_empty);

		spin_lock_init(&vss->lock);



		rc = virtsnd_pcm_build_hw(vss, &info[i]);

		if (rc)
@@ -477,3 +479,33 @@ 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;

	u32 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;

	}

}

sound/virtio/virtio_pcm.h

+40 −0
Original line number Diff line number Diff line
@@ -23,6 +23,17 @@ struct virtio_pcm_msg; 
 * @substream: Kernel ALSA substream.

 * @hw: Kernel ALSA substream hardware descriptor.

 * @elapsed_period: Kernel work to handle the elapsed period state.

 * @lock: Spinlock that protects fields shared by interrupt handlers and

 *        substream operators.

 * @buffer_bytes: Current buffer size in bytes.

 * @hw_ptr: Substream hardware pointer value in bytes [0 ... buffer_bytes).

 * @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;
@@ -33,6 +44,16 @@ struct virtio_pcm_substream { 
	struct snd_pcm_substream *substream;

	struct snd_pcm_hardware hw;

	struct work_struct elapsed_period;

	spinlock_t lock;

	size_t buffer_bytes;

	size_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;

};



/**
@@ -65,8 +86,27 @@ 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, u32 nid);



struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, u32 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);



unsigned int virtsnd_pcm_msg_pending_num(struct virtio_pcm_substream *vss);



#endif /* VIRTIO_SND_PCM_H */