Add dynamic layer for raspberrypi and rcar-gen3

Updates [v2]:
It backports the virtio-sound module for rcar-gen3 and enables
virtio-sound, virtio-can, virtio-input, virtio-console,
virtio-loopback for both cases.

Updates [v1]:
Add linux-renesas kernel configuration

Specifically this commit creates a new directory 'linux-renesas'
for configuring the required modules to be loaded by that kernel.
It is also backports the virtio-sound module and enables
virtio-sound, virtio-can, virtio-input, virtio-console and
virtio-loopback.

Virtio-sound module sources:
Source: https://lore.kernel.org/alsa-devel/20210302164709.3142702-1-anton.yakovlev@opensynergy.com

Bug-AGL: SPEC-4966

Change-Id: Ie143e690695a526958e07a66ba481887b2e4a248
Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>

1 files changed, 705 insertions, 0 deletions

diff --git a/meta-egvirt/dynamic-layers/rcar-gen3/recipes-kernel/linux/linux-common/0003-ALSA-virtio-build-PCM-devices-and-substream-hardware.patch b/meta-egvirt/dynamic-layers/rcar-gen3/recipes-kernel/linux/linux-common/0003-ALSA-virtio-build-PCM-devices-and-substream-hardware.patch
new file mode 100644
index 00000000..722c5b89
--- /dev/null
+++ b/meta-egvirt/dynamic-layers/rcar-gen3/recipes-kernel/linux/linux-common/0003-ALSA-virtio-build-PCM-devices-and-substream-hardware.patch
@@ -0,0 +1,705 @@
+From 9717557af201dd81cbc202660bc24d7b63558be6 Mon Sep 17 00:00:00 2001
+From: Anton Yakovlev <anton.yakovlev@opensynergy.com>
+Date: Tue, 2 Mar 2021 17:47:04 +0100
+Subject: [PATCH 3/9] ALSA: virtio: build PCM devices and substream hardware
+ descriptors
+
+Like the HDA specification, the virtio sound device specification links
+PCM substreams, jacks and PCM channel maps into functional groups. For
+each discovered group, a PCM device is created, the number of which
+coincides with the group number.
+
+Introduce the module parameters for setting the hardware buffer
+parameters:
+  pcm_buffer_ms [=160]
+  pcm_periods_min [=2]
+  pcm_periods_max [=16]
+  pcm_period_ms_min [=10]
+  pcm_period_ms_max [=80]
+
+Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
+Link: https://lore.kernel.org/r/20210302164709.3142702-5-anton.yakovlev@opensynergy.com
+Signed-off-by: Takashi Iwai <tiwai@suse.de>
+---
+ sound/virtio/Makefile      |   3 +-
+ sound/virtio/virtio_card.c |  18 ++
+ sound/virtio/virtio_card.h |  10 +
+ sound/virtio/virtio_pcm.c  | 479 +++++++++++++++++++++++++++++++++++++
+ sound/virtio/virtio_pcm.h  |  72 ++++++
+ 5 files changed, 581 insertions(+), 1 deletion(-)
+ create mode 100644 sound/virtio/virtio_pcm.c
+ create mode 100644 sound/virtio/virtio_pcm.h
+
+diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
+index dc551e637441..69162a545a41 100644
+--- a/sound/virtio/Makefile
++++ b/sound/virtio/Makefile
+@@ -4,5 +4,6 @@ obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
+ 
+ virtio_snd-objs := \
+ 	virtio_card.o \
+-	virtio_ctl_msg.o
++	virtio_ctl_msg.o \
++	virtio_pcm.o
+ 
+diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
+index b757b2444078..11c76ee311b7 100644
+--- a/sound/virtio/virtio_card.c
++++ b/sound/virtio/virtio_card.c
+@@ -209,6 +209,16 @@ static int virtsnd_build_devs(struct virtio_snd *snd)
+ 			 VIRTIO_SND_CARD_NAME " at %s/%s",
+ 			 dev_name(dev->parent), dev_name(dev));
+ 
++	rc = virtsnd_pcm_parse_cfg(snd);
++	if (rc)
++		return rc;
++
++	if (snd->nsubstreams) {
++		rc = virtsnd_pcm_build_devs(snd);
++		if (rc)
++			return rc;
++	}
++
+ 	return snd_card_register(snd->card);
+ }
+ 
+@@ -237,6 +247,9 @@ static int virtsnd_validate(struct virtio_device *vdev)
+ 		return -EINVAL;
+ 	}
+ 
++	if (virtsnd_pcm_validate(vdev))
++		return -EINVAL;
++
+ 	return 0;
+ }
+ 
+@@ -259,6 +272,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
+ 
+ 	snd->vdev = vdev;
+ 	INIT_LIST_HEAD(&snd->ctl_msgs);
++	INIT_LIST_HEAD(&snd->pcm_list);
+ 
+ 	vdev->priv = snd;
+ 
+@@ -293,6 +307,7 @@ 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;
+ 
+ 	virtsnd_disable_event_vq(snd);
+ 	virtsnd_ctl_msg_cancel_all(snd);
+@@ -303,6 +318,9 @@ 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);
++
+ 	kfree(snd->event_msgs);
+ }
+ 
+diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
+index 1e76eeff160f..77a1b7255370 100644
+--- a/sound/virtio/virtio_card.h
++++ b/sound/virtio/virtio_card.h
+@@ -12,9 +12,13 @@
+ #include <uapi/linux/virtio_snd.h>
+ 
+ #include "virtio_ctl_msg.h"
++#include "virtio_pcm.h"
+ 
+ #define VIRTIO_SND_CARD_DRIVER	"virtio-snd"
+ #define VIRTIO_SND_CARD_NAME	"VirtIO SoundCard"
++#define VIRTIO_SND_PCM_NAME	"VirtIO PCM"
++
++struct virtio_pcm_substream;
+ 
+ /**
+  * struct virtio_snd_queue - Virtqueue wrapper structure.
+@@ -33,6 +37,9 @@ struct virtio_snd_queue {
+  * @card: ALSA sound card.
+  * @ctl_msgs: Pending control request list.
+  * @event_msgs: Device events.
++ * @pcm_list: VirtIO PCM device list.
++ * @substreams: VirtIO PCM substreams.
++ * @nsubstreams: Number of PCM substreams.
+  */
+ struct virtio_snd {
+ 	struct virtio_device *vdev;
+@@ -40,6 +47,9 @@ struct virtio_snd {
+ 	struct snd_card *card;
+ 	struct list_head ctl_msgs;
+ 	struct virtio_snd_event *event_msgs;
++	struct list_head pcm_list;
++	struct virtio_pcm_substream *substreams;
++	u32 nsubstreams;
+ };
+ 
+ /* Message completion timeout in milliseconds (module parameter). */
+diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c
+new file mode 100644
+index 000000000000..e16567e2e214
+--- /dev/null
++++ b/sound/virtio/virtio_pcm.c
+@@ -0,0 +1,479 @@
++// SPDX-License-Identifier: GPL-2.0+
++/*
++ * virtio-snd: Virtio sound device
++ * Copyright (C) 2021 OpenSynergy GmbH
++ */
++#include <linux/moduleparam.h>
++#include <linux/virtio_config.h>
++
++#include "virtio_card.h"
++
++static u32 pcm_buffer_ms = 160;
++module_param(pcm_buffer_ms, uint, 0644);
++MODULE_PARM_DESC(pcm_buffer_ms, "PCM substream buffer time in milliseconds");
++
++static u32 pcm_periods_min = 2;
++module_param(pcm_periods_min, uint, 0644);
++MODULE_PARM_DESC(pcm_periods_min, "Minimum number of PCM periods");
++
++static u32 pcm_periods_max = 16;
++module_param(pcm_periods_max, uint, 0644);
++MODULE_PARM_DESC(pcm_periods_max, "Maximum number of PCM periods");
++
++static u32 pcm_period_ms_min = 10;
++module_param(pcm_period_ms_min, uint, 0644);
++MODULE_PARM_DESC(pcm_period_ms_min, "Minimum PCM period time in milliseconds");
++
++static u32 pcm_period_ms_max = 80;
++module_param(pcm_period_ms_max, uint, 0644);
++MODULE_PARM_DESC(pcm_period_ms_max, "Maximum PCM period time in milliseconds");
++
++/* Map for converting VirtIO format to ALSA format. */
++static const snd_pcm_format_t g_v2a_format_map[] = {
++	[VIRTIO_SND_PCM_FMT_IMA_ADPCM] = SNDRV_PCM_FORMAT_IMA_ADPCM,
++	[VIRTIO_SND_PCM_FMT_MU_LAW] = SNDRV_PCM_FORMAT_MU_LAW,
++	[VIRTIO_SND_PCM_FMT_A_LAW] = SNDRV_PCM_FORMAT_A_LAW,
++	[VIRTIO_SND_PCM_FMT_S8] = SNDRV_PCM_FORMAT_S8,
++	[VIRTIO_SND_PCM_FMT_U8] = SNDRV_PCM_FORMAT_U8,
++	[VIRTIO_SND_PCM_FMT_S16] = SNDRV_PCM_FORMAT_S16_LE,
++	[VIRTIO_SND_PCM_FMT_U16] = SNDRV_PCM_FORMAT_U16_LE,
++	[VIRTIO_SND_PCM_FMT_S18_3] = SNDRV_PCM_FORMAT_S18_3LE,
++	[VIRTIO_SND_PCM_FMT_U18_3] = SNDRV_PCM_FORMAT_U18_3LE,
++	[VIRTIO_SND_PCM_FMT_S20_3] = SNDRV_PCM_FORMAT_S20_3LE,
++	[VIRTIO_SND_PCM_FMT_U20_3] = SNDRV_PCM_FORMAT_U20_3LE,
++	[VIRTIO_SND_PCM_FMT_S24_3] = SNDRV_PCM_FORMAT_S24_3LE,
++	[VIRTIO_SND_PCM_FMT_U24_3] = SNDRV_PCM_FORMAT_U24_3LE,
++	[VIRTIO_SND_PCM_FMT_S20] = SNDRV_PCM_FORMAT_S20_LE,
++	[VIRTIO_SND_PCM_FMT_U20] = SNDRV_PCM_FORMAT_U20_LE,
++	[VIRTIO_SND_PCM_FMT_S24] = SNDRV_PCM_FORMAT_S24_LE,
++	[VIRTIO_SND_PCM_FMT_U24] = SNDRV_PCM_FORMAT_U24_LE,
++	[VIRTIO_SND_PCM_FMT_S32] = SNDRV_PCM_FORMAT_S32_LE,
++	[VIRTIO_SND_PCM_FMT_U32] = SNDRV_PCM_FORMAT_U32_LE,
++	[VIRTIO_SND_PCM_FMT_FLOAT] = SNDRV_PCM_FORMAT_FLOAT_LE,
++	[VIRTIO_SND_PCM_FMT_FLOAT64] = SNDRV_PCM_FORMAT_FLOAT64_LE,
++	[VIRTIO_SND_PCM_FMT_DSD_U8] = SNDRV_PCM_FORMAT_DSD_U8,
++	[VIRTIO_SND_PCM_FMT_DSD_U16] = SNDRV_PCM_FORMAT_DSD_U16_LE,
++	[VIRTIO_SND_PCM_FMT_DSD_U32] = SNDRV_PCM_FORMAT_DSD_U32_LE,
++	[VIRTIO_SND_PCM_FMT_IEC958_SUBFRAME] =
++		SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE
++};
++
++/* Map for converting VirtIO frame rate to ALSA frame rate. */
++struct virtsnd_v2a_rate {
++	unsigned int alsa_bit;
++	unsigned int rate;
++};
++
++static const struct virtsnd_v2a_rate g_v2a_rate_map[] = {
++	[VIRTIO_SND_PCM_RATE_5512] = { SNDRV_PCM_RATE_5512, 5512 },
++	[VIRTIO_SND_PCM_RATE_8000] = { SNDRV_PCM_RATE_8000, 8000 },
++	[VIRTIO_SND_PCM_RATE_11025] = { SNDRV_PCM_RATE_11025, 11025 },
++	[VIRTIO_SND_PCM_RATE_16000] = { SNDRV_PCM_RATE_16000, 16000 },
++	[VIRTIO_SND_PCM_RATE_22050] = { SNDRV_PCM_RATE_22050, 22050 },
++	[VIRTIO_SND_PCM_RATE_32000] = { SNDRV_PCM_RATE_32000, 32000 },
++	[VIRTIO_SND_PCM_RATE_44100] = { SNDRV_PCM_RATE_44100, 44100 },
++	[VIRTIO_SND_PCM_RATE_48000] = { SNDRV_PCM_RATE_48000, 48000 },
++	[VIRTIO_SND_PCM_RATE_64000] = { SNDRV_PCM_RATE_64000, 64000 },
++	[VIRTIO_SND_PCM_RATE_88200] = { SNDRV_PCM_RATE_88200, 88200 },
++	[VIRTIO_SND_PCM_RATE_96000] = { SNDRV_PCM_RATE_96000, 96000 },
++	[VIRTIO_SND_PCM_RATE_176400] = { SNDRV_PCM_RATE_176400, 176400 },
++	[VIRTIO_SND_PCM_RATE_192000] = { SNDRV_PCM_RATE_192000, 192000 }
++};
++
++/**
++ * virtsnd_pcm_build_hw() - Parse substream config and build HW descriptor.
++ * @vss: VirtIO substream.
++ * @info: VirtIO substream information entry.
++ *
++ * Context: Any context.
++ * Return: 0 on success, -EINVAL if configuration is invalid.
++ */
++static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss,
++				struct virtio_snd_pcm_info *info)
++{
++	struct virtio_device *vdev = vss->snd->vdev;
++	unsigned int i;
++	u64 values;
++	size_t sample_max = 0;
++	size_t sample_min = 0;
++
++	vss->features = le32_to_cpu(info->features);
++
++	/*
++	 * TODO: set SNDRV_PCM_INFO_{BATCH,BLOCK_TRANSFER} if device supports
++	 * only message-based transport.
++	 */
++	vss->hw.info =
++		SNDRV_PCM_INFO_MMAP |
++		SNDRV_PCM_INFO_MMAP_VALID |
++		SNDRV_PCM_INFO_BATCH |
++		SNDRV_PCM_INFO_BLOCK_TRANSFER |
++		SNDRV_PCM_INFO_INTERLEAVED |
++		SNDRV_PCM_INFO_PAUSE;
++
++	if (!info->channels_min || info->channels_min > info->channels_max) {
++		dev_err(&vdev->dev,
++			"SID %u: invalid channel range [%u %u]\n",
++			vss->sid, info->channels_min, info->channels_max);
++		return -EINVAL;
++	}
++
++	vss->hw.channels_min = info->channels_min;
++	vss->hw.channels_max = info->channels_max;
++
++	values = le64_to_cpu(info->formats);
++
++	vss->hw.formats = 0;
++
++	for (i = 0; i < ARRAY_SIZE(g_v2a_format_map); ++i)
++		if (values & (1ULL << i)) {
++			snd_pcm_format_t alsa_fmt = g_v2a_format_map[i];
++			int bytes = snd_pcm_format_physical_width(alsa_fmt) / 8;
++
++			if (!sample_min || sample_min > bytes)
++				sample_min = bytes;
++
++			if (sample_max < bytes)
++				sample_max = bytes;
++
++			vss->hw.formats |= pcm_format_to_bits(alsa_fmt);
++		}
++
++	if (!vss->hw.formats) {
++		dev_err(&vdev->dev,
++			"SID %u: no supported PCM sample formats found\n",
++			vss->sid);
++		return -EINVAL;
++	}
++
++	values = le64_to_cpu(info->rates);
++
++	vss->hw.rates = 0;
++
++	for (i = 0; i < ARRAY_SIZE(g_v2a_rate_map); ++i)
++		if (values & (1ULL << i)) {
++			if (!vss->hw.rate_min ||
++			    vss->hw.rate_min > g_v2a_rate_map[i].rate)
++				vss->hw.rate_min = g_v2a_rate_map[i].rate;
++
++			if (vss->hw.rate_max < g_v2a_rate_map[i].rate)
++				vss->hw.rate_max = g_v2a_rate_map[i].rate;
++
++			vss->hw.rates |= g_v2a_rate_map[i].alsa_bit;
++		}
++
++	if (!vss->hw.rates) {
++		dev_err(&vdev->dev,
++			"SID %u: no supported PCM frame rates found\n",
++			vss->sid);
++		return -EINVAL;
++	}
++
++	vss->hw.periods_min = pcm_periods_min;
++	vss->hw.periods_max = pcm_periods_max;
++
++	/*
++	 * We must ensure that there is enough space in the buffer to store
++	 * pcm_buffer_ms ms for the combination (Cmax, Smax, Rmax), where:
++	 *   Cmax = maximum supported number of channels,
++	 *   Smax = maximum supported sample size in bytes,
++	 *   Rmax = maximum supported frame rate.
++	 */
++	vss->hw.buffer_bytes_max =
++		PAGE_ALIGN(sample_max * vss->hw.channels_max * pcm_buffer_ms *
++			   (vss->hw.rate_max / MSEC_PER_SEC));
++
++	/*
++	 * We must ensure that the minimum period size is enough to store
++	 * pcm_period_ms_min ms for the combination (Cmin, Smin, Rmin), where:
++	 *   Cmin = minimum supported number of channels,
++	 *   Smin = minimum supported sample size in bytes,
++	 *   Rmin = minimum supported frame rate.
++	 */
++	vss->hw.period_bytes_min =
++		sample_min * vss->hw.channels_min * pcm_period_ms_min *
++		(vss->hw.rate_min / MSEC_PER_SEC);
++
++	/*
++	 * We must ensure that the maximum period size is enough to store
++	 * pcm_period_ms_max ms for the combination (Cmax, Smax, Rmax).
++	 */
++	vss->hw.period_bytes_max =
++		sample_max * vss->hw.channels_max * pcm_period_ms_max *
++		(vss->hw.rate_max / MSEC_PER_SEC);
++
++	return 0;
++}
++
++/**
++ * virtsnd_pcm_find() - Find the PCM device for the specified node ID.
++ * @snd: VirtIO sound device.
++ * @nid: Function node ID.
++ *
++ * Context: Any context.
++ * Return: a pointer to the PCM device or ERR_PTR(-ENOENT).
++ */
++struct virtio_pcm *virtsnd_pcm_find(struct virtio_snd *snd, u32 nid)
++{
++	struct virtio_pcm *vpcm;
++
++	list_for_each_entry(vpcm, &snd->pcm_list, list)
++		if (vpcm->nid == nid)
++			return vpcm;
++
++	return ERR_PTR(-ENOENT);
++}
++
++/**
++ * virtsnd_pcm_find_or_create() - Find or create the PCM device for the
++ *                                specified node ID.
++ * @snd: VirtIO sound device.
++ * @nid: Function node ID.
++ *
++ * Context: Any context that permits to sleep.
++ * Return: a pointer to the PCM device or ERR_PTR(-errno).
++ */
++struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, u32 nid)
++{
++	struct virtio_device *vdev = snd->vdev;
++	struct virtio_pcm *vpcm;
++
++	vpcm = virtsnd_pcm_find(snd, nid);
++	if (!IS_ERR(vpcm))
++		return vpcm;
++
++	vpcm = devm_kzalloc(&vdev->dev, sizeof(*vpcm), GFP_KERNEL);
++	if (!vpcm)
++		return ERR_PTR(-ENOMEM);
++
++	vpcm->nid = nid;
++	list_add_tail(&vpcm->list, &snd->pcm_list);
++
++	return vpcm;
++}
++
++/**
++ * virtsnd_pcm_validate() - Validate if the device can be started.
++ * @vdev: VirtIO parent device.
++ *
++ * Context: Any context.
++ * Return: 0 on success, -EINVAL on failure.
++ */
++int virtsnd_pcm_validate(struct virtio_device *vdev)
++{
++	if (pcm_periods_min < 2 || pcm_periods_min > pcm_periods_max) {
++		dev_err(&vdev->dev,
++			"invalid range [%u %u] of the number of PCM periods\n",
++			pcm_periods_min, pcm_periods_max);
++		return -EINVAL;
++	}
++
++	if (!pcm_period_ms_min || pcm_period_ms_min > pcm_period_ms_max) {
++		dev_err(&vdev->dev,
++			"invalid range [%u %u] of the size of the PCM period\n",
++			pcm_period_ms_min, pcm_period_ms_max);
++		return -EINVAL;
++	}
++
++	if (pcm_buffer_ms < pcm_periods_min * pcm_period_ms_min) {
++		dev_err(&vdev->dev,
++			"pcm_buffer_ms(=%u) value cannot be < %u ms\n",
++			pcm_buffer_ms, pcm_periods_min * pcm_period_ms_min);
++		return -EINVAL;
++	}
++
++	if (pcm_period_ms_max > pcm_buffer_ms / 2) {
++		dev_err(&vdev->dev,
++			"pcm_period_ms_max(=%u) value cannot be > %u ms\n",
++			pcm_period_ms_max, pcm_buffer_ms / 2);
++		return -EINVAL;
++	}
++
++	return 0;
++}
++
++/**
++ * virtsnd_pcm_period_elapsed() - Kernel work function to handle the elapsed
++ *                                period state.
++ * @work: Elapsed period work.
++ *
++ * The main purpose of this function is to call snd_pcm_period_elapsed() in
++ * a process context, not in an interrupt context. This is necessary because PCM
++ * devices operate in non-atomic mode.
++ *
++ * Context: Process context.
++ */
++static void virtsnd_pcm_period_elapsed(struct work_struct *work)
++{
++	struct virtio_pcm_substream *vss =
++		container_of(work, struct virtio_pcm_substream, elapsed_period);
++
++	snd_pcm_period_elapsed(vss->substream);
++}
++
++/**
++ * virtsnd_pcm_parse_cfg() - Parse the stream configuration.
++ * @snd: VirtIO sound device.
++ *
++ * This function is called during initial device initialization.
++ *
++ * Context: Any context that permits to sleep.
++ * Return: 0 on success, -errno on failure.
++ */
++int virtsnd_pcm_parse_cfg(struct virtio_snd *snd)
++{
++	struct virtio_device *vdev = snd->vdev;
++	struct virtio_snd_pcm_info *info;
++	u32 i;
++	int rc;
++
++	virtio_cread_le(vdev, struct virtio_snd_config, streams,
++			&snd->nsubstreams);
++	if (!snd->nsubstreams)
++		return 0;
++
++	snd->substreams = devm_kcalloc(&vdev->dev, snd->nsubstreams,
++				       sizeof(*snd->substreams), GFP_KERNEL);
++	if (!snd->substreams)
++		return -ENOMEM;
++
++	info = kcalloc(snd->nsubstreams, sizeof(*info), GFP_KERNEL);
++	if (!info)
++		return -ENOMEM;
++
++	rc = virtsnd_ctl_query_info(snd, VIRTIO_SND_R_PCM_INFO, 0,
++				    snd->nsubstreams, sizeof(*info), info);
++	if (rc)
++		goto on_exit;
++
++	for (i = 0; i < snd->nsubstreams; ++i) {
++		struct virtio_pcm_substream *vss = &snd->substreams[i];
++		struct virtio_pcm *vpcm;
++
++		vss->snd = snd;
++		vss->sid = i;
++		INIT_WORK(&vss->elapsed_period, virtsnd_pcm_period_elapsed);
++
++		rc = virtsnd_pcm_build_hw(vss, &info[i]);
++		if (rc)
++			goto on_exit;
++
++		vss->nid = le32_to_cpu(info[i].hdr.hda_fn_nid);
++
++		vpcm = virtsnd_pcm_find_or_create(snd, vss->nid);
++		if (IS_ERR(vpcm)) {
++			rc = PTR_ERR(vpcm);
++			goto on_exit;
++		}
++
++		switch (info[i].direction) {
++		case VIRTIO_SND_D_OUTPUT:
++			vss->direction = SNDRV_PCM_STREAM_PLAYBACK;
++			break;
++		case VIRTIO_SND_D_INPUT:
++			vss->direction = SNDRV_PCM_STREAM_CAPTURE;
++			break;
++		default:
++			dev_err(&vdev->dev, "SID %u: unknown direction (%u)\n",
++				vss->sid, info[i].direction);
++			rc = -EINVAL;
++			goto on_exit;
++		}
++
++		vpcm->streams[vss->direction].nsubstreams++;
++	}
++
++on_exit:
++	kfree(info);
++
++	return rc;
++}
++
++/**
++ * virtsnd_pcm_build_devs() - Build ALSA PCM devices.
++ * @snd: VirtIO sound device.
++ *
++ * Context: Any context that permits to sleep.
++ * Return: 0 on success, -errno on failure.
++ */
++int virtsnd_pcm_build_devs(struct virtio_snd *snd)
++{
++	struct virtio_device *vdev = snd->vdev;
++	struct virtio_pcm *vpcm;
++	u32 i;
++	int rc;
++
++	list_for_each_entry(vpcm, &snd->pcm_list, list) {
++		unsigned int npbs =
++			vpcm->streams[SNDRV_PCM_STREAM_PLAYBACK].nsubstreams;
++		unsigned int ncps =
++			vpcm->streams[SNDRV_PCM_STREAM_CAPTURE].nsubstreams;
++
++		if (!npbs && !ncps)
++			continue;
++
++		rc = snd_pcm_new(snd->card, VIRTIO_SND_CARD_DRIVER, vpcm->nid,
++				 npbs, ncps, &vpcm->pcm);
++		if (rc) {
++			dev_err(&vdev->dev, "snd_pcm_new[%u] failed: %d\n",
++				vpcm->nid, rc);
++			return rc;
++		}
++
++		vpcm->pcm->info_flags = 0;
++		vpcm->pcm->dev_class = SNDRV_PCM_CLASS_GENERIC;
++		vpcm->pcm->dev_subclass = SNDRV_PCM_SUBCLASS_GENERIC_MIX;
++		snprintf(vpcm->pcm->name, sizeof(vpcm->pcm->name),
++			 VIRTIO_SND_PCM_NAME " %u", vpcm->pcm->device);
++		vpcm->pcm->private_data = vpcm;
++		vpcm->pcm->nonatomic = true;
++
++		for (i = 0; i < ARRAY_SIZE(vpcm->streams); ++i) {
++			struct virtio_pcm_stream *stream = &vpcm->streams[i];
++
++			if (!stream->nsubstreams)
++				continue;
++
++			stream->substreams =
++				devm_kcalloc(&vdev->dev, stream->nsubstreams,
++					     sizeof(*stream->substreams),
++					     GFP_KERNEL);
++			if (!stream->substreams)
++				return -ENOMEM;
++
++			stream->nsubstreams = 0;
++		}
++	}
++
++	for (i = 0; i < snd->nsubstreams; ++i) {
++		struct virtio_pcm_stream *vs;
++		struct virtio_pcm_substream *vss = &snd->substreams[i];
++
++		vpcm = virtsnd_pcm_find(snd, vss->nid);
++		if (IS_ERR(vpcm))
++			return PTR_ERR(vpcm);
++
++		vs = &vpcm->streams[vss->direction];
++		vs->substreams[vs->nsubstreams++] = vss;
++	}
++
++	list_for_each_entry(vpcm, &snd->pcm_list, list) {
++		for (i = 0; i < ARRAY_SIZE(vpcm->streams); ++i) {
++			struct virtio_pcm_stream *vs = &vpcm->streams[i];
++			struct snd_pcm_str *ks = &vpcm->pcm->streams[i];
++			struct snd_pcm_substream *kss;
++
++			if (!vs->nsubstreams)
++				continue;
++
++			for (kss = ks->substream; kss; kss = kss->next)
++				vs->substreams[kss->number]->substream = kss;
++		}
++
++		snd_pcm_set_managed_buffer_all(vpcm->pcm,
++					       SNDRV_DMA_TYPE_VMALLOC, NULL,
++					       0, 0);
++	}
++
++	return 0;
++}
+diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h
+new file mode 100644
+index 000000000000..84f2f3f14f48
+--- /dev/null
++++ b/sound/virtio/virtio_pcm.h
+@@ -0,0 +1,72 @@
++/* SPDX-License-Identifier: GPL-2.0+ */
++/*
++ * virtio-snd: Virtio sound device
++ * Copyright (C) 2021 OpenSynergy GmbH
++ */
++#ifndef VIRTIO_SND_PCM_H
++#define VIRTIO_SND_PCM_H
++
++#include <linux/atomic.h>
++#include <linux/virtio_config.h>
++#include <sound/pcm.h>
++
++struct virtio_pcm;
++struct virtio_pcm_msg;
++
++/**
++ * struct virtio_pcm_substream - VirtIO PCM substream.
++ * @snd: VirtIO sound device.
++ * @nid: Function group node identifier.
++ * @sid: Stream identifier.
++ * @direction: Stream data flow direction (SNDRV_PCM_STREAM_XXX).
++ * @features: Stream VirtIO feature bit map (1 << VIRTIO_SND_PCM_F_XXX).
++ * @substream: Kernel ALSA substream.
++ * @hw: Kernel ALSA substream hardware descriptor.
++ * @elapsed_period: Kernel work to handle the elapsed period state.
++ */
++struct virtio_pcm_substream {
++	struct virtio_snd *snd;
++	u32 nid;
++	u32 sid;
++	u32 direction;
++	u32 features;
++	struct snd_pcm_substream *substream;
++	struct snd_pcm_hardware hw;
++	struct work_struct elapsed_period;
++};
++
++/**
++ * struct virtio_pcm_stream - VirtIO PCM stream.
++ * @substreams: VirtIO substreams belonging to the stream.
++ * @nsubstreams: Number of substreams.
++ */
++struct virtio_pcm_stream {
++	struct virtio_pcm_substream **substreams;
++	u32 nsubstreams;
++};
++
++/**
++ * struct virtio_pcm - VirtIO PCM device.
++ * @list: VirtIO PCM list entry.
++ * @nid: Function group node identifier.
++ * @pcm: Kernel PCM device.
++ * @streams: VirtIO PCM streams (playback and capture).
++ */
++struct virtio_pcm {
++	struct list_head list;
++	u32 nid;
++	struct snd_pcm *pcm;
++	struct virtio_pcm_stream streams[SNDRV_PCM_STREAM_LAST + 1];
++};
++
++int virtsnd_pcm_validate(struct virtio_device *vdev);
++
++int virtsnd_pcm_parse_cfg(struct virtio_snd *snd);
++
++int virtsnd_pcm_build_devs(struct virtio_snd *snd);
++
++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);
++
++#endif /* VIRTIO_SND_PCM_H */
+-- 
+2.34.1
+