[PATCH v2 0/9] ALSA: add virtio sound driver

@@ -51,6 +51,7 @@
 #define VIRTIO_ID_PSTORE		22 /* virtio pstore device */
 #define VIRTIO_ID_IOMMU			23 /* virtio IOMMU */
 #define VIRTIO_ID_MEM			24 /* virtio mem */
+#define VIRTIO_ID_SOUND			25 /* virtio sound */
 #define VIRTIO_ID_FS			26 /* virtio filesystem */
 #define VIRTIO_ID_PMEM			27 /* virtio pmem */
 #define VIRTIO_ID_MAC80211_HWSIM	29 /* virtio mac80211-hwsim */

@@ -3,5 +3,6 @@
 obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
 
 virtio_snd-objs := \
-	virtio_card.o
+	virtio_card.o \
+	virtio_ctl_msg.o
 

@@ -24,6 +24,10 @@
 
 #include "virtio_card.h"
 
+int msg_timeout_ms = MSEC_PER_SEC;
+module_param(msg_timeout_ms, int, 0644);
+MODULE_PARM_DESC(msg_timeout_ms, "Message completion timeout in milliseconds");
+
 static void virtsnd_remove(struct virtio_device *vdev);
 
 /**

@@ -125,6 +129,7 @@ static int virtsnd_find_vqs(struct virtio_snd *snd)
 	unsigned int n = 0;
 	int rc;
 
+	callbacks[VIRTIO_SND_VQ_CONTROL] = virtsnd_ctl_notify_cb;
 	callbacks[VIRTIO_SND_VQ_EVENT] = virtsnd_event_notify_cb;
 
 	rc = virtio_find_vqs(vdev, VIRTIO_SND_VQ_MAX, vqs, callbacks, names,

@@ -193,6 +198,15 @@ static void virtsnd_disable_vqs(struct virtio_snd *snd)
 		if (queue->vqueue)
 			virtqueue_disable_cb(queue->vqueue);
 		queue->vqueue = NULL;
+		/* Cancel all pending requests for the control queue */
+		if (i == VIRTIO_SND_VQ_CONTROL) {
+			struct virtio_snd_msg *msg;
+			struct virtio_snd_msg *next;
+
+			list_for_each_entry_safe(msg, next, &snd->ctl_msgs,
+						 list)
+				virtsnd_ctl_msg_complete(snd, msg);
+		}
 		spin_unlock_irqrestore(&queue->lock, flags);
 	}
 

@@ -283,6 +297,11 @@ static int virtsnd_validate(struct virtio_device *vdev)
 		return -EINVAL;
 	}
 
+	if (!msg_timeout_ms) {
+		dev_err(&vdev->dev, "msg_timeout_ms value cannot be zero\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 

@@ -305,6 +324,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
 
 	snd->vdev = vdev;
 	INIT_WORK(&snd->reset_work, virtsnd_reset_fn);
+	INIT_LIST_HEAD(&snd->ctl_msgs);
 
 	vdev->priv = snd;
 

@@ -23,6 +23,8 @@
 #include <sound/core.h>
 #include <uapi/linux/virtio_snd.h>
 
+#include "virtio_ctl_msg.h"
+
 /**
  * struct virtio_snd_queue - Virtqueue wrapper structure.
  * @lock: Used to synchronize access to a virtqueue.

@@ -39,6 +41,7 @@ struct virtio_snd_queue {
  * @queues: Virtqueue wrappers.
  * @reset_work: Reset device work.
  * @card: ALSA sound card.
+ * @ctl_msgs: Pending control request list.
  * @event_msgs: Device events.
  */
 struct virtio_snd {

@@ -46,9 +49,13 @@ struct virtio_snd {
 	struct virtio_snd_queue queues[VIRTIO_SND_VQ_MAX];
 	struct work_struct reset_work;
 	struct snd_card *card;
+	struct list_head ctl_msgs;
 	struct virtio_snd_event *event_msgs;
 };
 
+/* Message completion timeout in milliseconds (module parameter). */
+extern int msg_timeout_ms;
+
 static inline struct virtio_snd_queue *
 virtsnd_control_queue(struct virtio_snd *snd)
 {

@@ -0,0 +1,293 @@
+// 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 <linux/moduleparam.h>
+#include <linux/virtio_config.h>
+
+#include "virtio_card.h"
+#include "virtio_ctl_msg.h"
+
+/**
+ * virtsnd_ctl_msg_alloc_ext() - Allocate and initialize a control message.
+ * @vdev: VirtIO parent device.
+ * @request_size: Size of request header (pointed to by sg_request field).
+ * @response_size: Size of response header (pointed to by sg_response field).
+ * @sgs: Additional data to attach to the message (may be NULL).
+ * @out_sgs: Number of scattergather elements to attach to the request header.
+ * @in_sgs: Number of scattergather elements to attach to the response header.
+ * @gfp: Kernel flags for memory allocation.
+ *
+ * The message will be automatically freed when the ref_count value is 0.
+ *
+ * Context: Any context. May sleep if @gfp flags permit.
+ * Return: Allocated message on success, ERR_PTR(-errno) on failure.
+ */
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc_ext(struct virtio_device *vdev,
+						 size_t request_size,
+						 size_t response_size,
+						 struct scatterlist *sgs,
+						 unsigned int out_sgs,
+						 unsigned int in_sgs, gfp_t gfp)
+{
+	struct virtio_snd_msg *msg;
+	size_t msg_size =
+		sizeof(*msg) + (1 + out_sgs + 1 + in_sgs) * sizeof(*msg->sgs);
+	unsigned int i;
+
+	msg = devm_kzalloc(&vdev->dev, msg_size + request_size + response_size,
+			   gfp);
+	if (!msg)
+		return ERR_PTR(-ENOMEM);
+
+	sg_init_one(&msg->sg_request, (u8 *)msg + msg_size, request_size);
+	sg_init_one(&msg->sg_response, (u8 *)msg + msg_size + request_size,
+		    response_size);
+
+	INIT_LIST_HEAD(&msg->list);
+	init_completion(&msg->notify);
+	atomic_set(&msg->ref_count, 1);
+
+	msg->sgs[msg->out_sgs++] = &msg->sg_request;
+	if (sgs)
+		for (i = 0; i < out_sgs; ++i)
+			msg->sgs[msg->out_sgs++] = &sgs[i];
+
+	msg->sgs[msg->out_sgs + msg->in_sgs++] = &msg->sg_response;
+	if (sgs)
+		for (i = out_sgs; i < out_sgs + in_sgs; ++i)
+			msg->sgs[msg->out_sgs + msg->in_sgs++] = &sgs[i];
+
+	return msg;
+}
+
+/**
+ * virtsnd_ctl_msg_send() - Send an (asynchronous) control message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * If a message is failed to be enqueued, it will be deleted. If message content
+ * is still needed, the caller must additionally to virtsnd_ctl_msg_ref/unref()
+ * it.
+ *
+ * Context: Any context. Takes and releases the control queue spinlock.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
+	struct virtio_snd_hdr *response = sg_virt(&msg->sg_response);
+	bool notify = false;
+	unsigned long flags;
+	int rc = -EIO;
+
+	/* Set the default status in case the message was not sent or was
+	 * canceled.
+	 */
+	response->code = cpu_to_virtio32(vdev, VIRTIO_SND_S_IO_ERR);
+
+	spin_lock_irqsave(&queue->lock, flags);
+	if (queue->vqueue) {
+		rc = virtqueue_add_sgs(queue->vqueue, msg->sgs, msg->out_sgs,
+				       msg->in_sgs, msg, GFP_ATOMIC);
+		if (!rc) {
+			notify = virtqueue_kick_prepare(queue->vqueue);
+			list_add_tail(&msg->list, &snd->ctl_msgs);
+		}
+	}
+	spin_unlock_irqrestore(&queue->lock, flags);
+
+	if (!rc) {
+		if (!notify || virtqueue_notify(queue->vqueue))
+			return 0;
+
+		spin_lock_irqsave(&queue->lock, flags);
+		list_del(&msg->list);
+		spin_unlock_irqrestore(&queue->lock, flags);
+	}
+
+	virtsnd_ctl_msg_unref(snd->vdev, msg);
+
+	return -EIO;
+}
+
+/**
+ * virtsnd_ctl_msg_send_sync() - Send a (synchronous) control message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * After returning from this function, the message will be deleted. If message
+ * content is still needed, the caller must additionally to
+ * virtsnd_ctl_msg_ref/unref() it.
+ *
+ * The msg_timeout_ms module parameter defines the message completion timeout.
+ * If the message is not completed within this time, the function will return an
+ * error.
+ *
+ * Context: Any context. Takes and releases the control queue spinlock.
+ * Return: 0 on success, -errno on failure.
+ *
+ * The return value is a message status code (VIRTIO_SND_S_XXX) converted to an
+ * appropriate -errno value.
+ */
+int virtsnd_ctl_msg_send_sync(struct virtio_snd *snd,
+			      struct virtio_snd_msg *msg)
+{
+	struct virtio_device *vdev = snd->vdev;
+	unsigned int js = msecs_to_jiffies(msg_timeout_ms);
+	struct virtio_snd_hdr *response;
+	int rc;
+
+	virtsnd_ctl_msg_ref(vdev, msg);
+
+	rc = virtsnd_ctl_msg_send(snd, msg);
+	if (rc)
+		goto on_failure;
+
+	rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
+	if (rc <= 0) {
+		if (!rc) {
+			struct virtio_snd_hdr *request =
+				sg_virt(&msg->sg_request);
+
+			dev_err(&vdev->dev,
+				"control message (0x%08x) timeout\n",
+				le32_to_cpu(request->code));
+			rc = -EIO;
+		}
+
+		goto on_failure;
+	}
+
+	response = sg_virt(&msg->sg_response);
+
+	switch (le32_to_cpu(response->code)) {
+	case VIRTIO_SND_S_OK:
+		rc = 0;
+		break;
+	case VIRTIO_SND_S_BAD_MSG:
+		rc = -EINVAL;
+		break;
+	case VIRTIO_SND_S_NOT_SUPP:
+		rc = -EOPNOTSUPP;
+		break;
+	case VIRTIO_SND_S_IO_ERR:
+		rc = -EIO;
+		break;
+	default:
+		rc = -EPERM;
+		break;
+	}
+
+on_failure:
+	virtsnd_ctl_msg_unref(vdev, msg);
+
+	return rc;
+}
+
+/**
+ * virtsnd_ctl_msg_complete() - Complete a control message.
+ * @snd: VirtIO sound device.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ */
+void virtsnd_ctl_msg_complete(struct virtio_snd *snd,
+			      struct virtio_snd_msg *msg)
+{
+	list_del(&msg->list);
+	complete(&msg->notify);
+
+	virtsnd_ctl_msg_unref(snd->vdev, msg);
+}
+
+/**
+ * virtsnd_ctl_query_info() - Query the item configuration from the device.
+ * @snd: VirtIO sound device.
+ * @command: Control request code (VIRTIO_SND_R_XXX_INFO).
+ * @start_id: Item start identifier.
+ * @count: Item count to query.
+ * @size: Item information size in bytes.
+ * @info: Buffer for storing item information.
+ *
+ * Context: Any context that permits to sleep.
+ * Return: 0 on success, -errno on failure.
+ */
+int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
+			   int count, size_t size, void *info)
+{
+	struct virtio_device *vdev = snd->vdev;
+	struct virtio_snd_msg *msg;
+	struct virtio_snd_query_info *query;
+	struct scatterlist sg;
+
+	sg_init_one(&sg, info, count * size);
+
+	msg = virtsnd_ctl_msg_alloc_ext(vdev, sizeof(*query),
+					sizeof(struct virtio_snd_hdr), &sg, 0,
+					1, GFP_KERNEL);
+	if (IS_ERR(msg))
+		return PTR_ERR(msg);
+
+	query = sg_virt(&msg->sg_request);
+	query->hdr.code = cpu_to_virtio32(vdev, command);
+	query->start_id = cpu_to_virtio32(vdev, start_id);
+	query->count = cpu_to_virtio32(vdev, count);
+	query->size = cpu_to_virtio32(vdev, size);
+
+	return virtsnd_ctl_msg_send_sync(snd, msg);
+}
+
+/**
+ * virtsnd_ctl_notify_cb() - Process all completed control messages.
+ * @vqueue: Underlying control virtqueue.
+ *
+ * This callback function is called upon a vring interrupt request from the
+ * device.
+ *
+ * Context: Interrupt context. Takes and releases the control queue spinlock.
+ */
+void virtsnd_ctl_notify_cb(struct virtqueue *vqueue)
+{
+	struct virtio_snd *snd = vqueue->vdev->priv;
+	struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
+	unsigned long flags;
+
+	spin_lock_irqsave(&queue->lock, flags);
+	while (queue->vqueue) {
+		virtqueue_disable_cb(queue->vqueue);
+
+		for (;;) {
+			struct virtio_snd_msg *msg;
+			u32 length;
+
+			msg = virtqueue_get_buf(queue->vqueue, &length);
+			if (!msg)
+				break;
+
+			virtsnd_ctl_msg_complete(snd, msg);
+		}
+
+		if (unlikely(virtqueue_is_broken(queue->vqueue)))
+			break;
+
+		if (virtqueue_enable_cb(queue->vqueue))
+			break;
+	}
+	spin_unlock_irqrestore(&queue->lock, flags);
+}

@@ -0,0 +1,122 @@
+/* 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/>.
+ */
+#ifndef VIRTIO_SND_MSG_H
+#define VIRTIO_SND_MSG_H
+
+#include <linux/atomic.h>
+#include <linux/virtio.h>
+
+struct virtio_snd;
+
+/**
+ * struct virtio_snd_msg - Control message.
+ * @sg_request: Scattergather element containing a device request (header).
+ * @sg_response: Scattergather element containing a device response (status).
+ * @list: Pending message list entry.
+ * @notify: Request completed notification.
+ * @ref_count: Reference count used to manage a message lifetime.
+ * @out_sgs: Number of read-only sg elements in the sgs array.
+ * @in_sgs: Number of write-only sg elements in the sgs array.
+ * @sgs: Array of sg elements to add to the control virtqueue.
+ */
+struct virtio_snd_msg {
+/* public: */
+	struct scatterlist sg_request;
+	struct scatterlist sg_response;
+/* private: internal use only */
+	struct list_head list;
+	struct completion notify;
+	atomic_t ref_count;
+	unsigned int out_sgs;
+	unsigned int in_sgs;
+	struct scatterlist *sgs[0];
+};
+
+/**
+ * virtsnd_ctl_msg_ref() - Increment reference counter for the message.
+ * @vdev: VirtIO parent device.
+ * @msg: Control message.
+ *
+ * Context: Any context.
+ */
+static inline void virtsnd_ctl_msg_ref(struct virtio_device *vdev,
+				       struct virtio_snd_msg *msg)
+{
+	atomic_inc(&msg->ref_count);
+}
+
+/**
+ * virtsnd_ctl_msg_unref() - Decrement reference counter for the message.
+ * @vdev: VirtIO parent device.
+ * @msg: Control message.
+ *
+ * The message will be freed when the ref_count value is 0.
+ *
+ * Context: Any context.
+ */
+static inline void virtsnd_ctl_msg_unref(struct virtio_device *vdev,
+					 struct virtio_snd_msg *msg)
+{
+	if (!atomic_dec_return(&msg->ref_count))
+		devm_kfree(&vdev->dev, msg);
+}
+
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc_ext(struct virtio_device *vdev,
+						 size_t request_size,
+						 size_t response_size,
+						 struct scatterlist *sgs,
+						 unsigned int out_sgs,
+						 unsigned int in_sgs,
+						 gfp_t gfp);
+
+/**
+ * virtsnd_ctl_msg_alloc() - Simplified control message allocation.
+ * @vdev: VirtIO parent device.
+ * @request_size: Size of request header (pointed to by sg_request field).
+ * @response_size: Size of response header (pointed to by sg_response field).
+ * @gfp: Kernel flags for memory allocation.
+ *
+ * The message will be automatically freed when the ref_count value is 0.
+ *
+ * Context: Any context. May sleep if @gfp flags permit.
+ * Return: Allocated message on success, ERR_PTR(-errno) on failure.
+ */
+static inline
+struct virtio_snd_msg *virtsnd_ctl_msg_alloc(struct virtio_device *vdev,
+					     size_t request_size,
+					     size_t response_size, gfp_t gfp)
+{
+	return virtsnd_ctl_msg_alloc_ext(vdev, request_size, response_size,
+					 NULL, 0, 0, gfp);
+}
+
+int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg);
+
+int virtsnd_ctl_msg_send_sync(struct virtio_snd *snd,
+			      struct virtio_snd_msg *msg);
+
+void virtsnd_ctl_msg_complete(struct virtio_snd *snd,
+			      struct virtio_snd_msg *msg);
+
+int virtsnd_ctl_query_info(struct virtio_snd *snd, int command, int start_id,
+			   int count, size_t size, void *info);
+
+void virtsnd_ctl_notify_cb(struct virtqueue *vqueue);
+
+#endif /* VIRTIO_SND_MSG_H */

@@ -18936,6 +18936,15 @@ W:	https://virtio-mem.gitlab.io/
 F:	drivers/virtio/virtio_mem.c
 F:	include/uapi/linux/virtio_mem.h
 
+VIRTIO SOUND DRIVER
+M:	Anton Yakovlev <anton.yakovlev@opensynergy.com>
+M:	"Michael S. Tsirkin" <mst@redhat.com>
+L:	virtualization@lists.linux-foundation.org
+L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
+S:	Maintained
+F:	include/uapi/linux/virtio_snd.h
+F:	sound/virtio/*
+
 VIRTUAL BOX GUEST DEVICE DRIVER
 M:	Hans de Goede <hdegoede@redhat.com>
 M:	Arnd Bergmann <arnd@arndb.de>

@@ -0,0 +1,361 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (C) 2020  OpenSynergy GmbH
+ *
+ * This header is BSD licensed so anyone can use the definitions to
+ * implement compatible drivers/servers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of OpenSynergy GmbH nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#ifndef VIRTIO_SND_IF_H
+#define VIRTIO_SND_IF_H
+
+#include <linux/virtio_types.h>
+
+/*******************************************************************************
+ * CONFIGURATION SPACE
+ */
+struct virtio_snd_config {
+	/* # of available physical jacks */
+	__le32 jacks;
+	/* # of available PCM streams */
+	__le32 streams;
+	/* # of available channel maps */
+	__le32 chmaps;
+};
+
+enum {
+	/* device virtqueue indexes */
+	VIRTIO_SND_VQ_CONTROL = 0,
+	VIRTIO_SND_VQ_EVENT,
+	VIRTIO_SND_VQ_TX,
+	VIRTIO_SND_VQ_RX,
+	/* # of device virtqueues */
+	VIRTIO_SND_VQ_MAX
+};
+
+/*******************************************************************************
+ * COMMON DEFINITIONS
+ */
+
+/* supported dataflow directions */
+enum {
+	VIRTIO_SND_D_OUTPUT = 0,
+	VIRTIO_SND_D_INPUT
+};
+
+enum {
+	/* jack control request types */
+	VIRTIO_SND_R_JACK_INFO = 1,
+	VIRTIO_SND_R_JACK_REMAP,
+
+	/* PCM control request types */
+	VIRTIO_SND_R_PCM_INFO = 0x0100,
+	VIRTIO_SND_R_PCM_SET_PARAMS,
+	VIRTIO_SND_R_PCM_PREPARE,
+	VIRTIO_SND_R_PCM_RELEASE,
+	VIRTIO_SND_R_PCM_START,
+	VIRTIO_SND_R_PCM_STOP,
+
+	/* channel map control request types */
+	VIRTIO_SND_R_CHMAP_INFO = 0x0200,
+
+	/* jack event types */
+	VIRTIO_SND_EVT_JACK_CONNECTED = 0x1000,
+	VIRTIO_SND_EVT_JACK_DISCONNECTED,
+
+	/* PCM event types */
+	VIRTIO_SND_EVT_PCM_PERIOD_ELAPSED = 0x1100,
+	VIRTIO_SND_EVT_PCM_XRUN,
+
+	/* common status codes */
+	VIRTIO_SND_S_OK = 0x8000,
+	VIRTIO_SND_S_BAD_MSG,
+	VIRTIO_SND_S_NOT_SUPP,
+	VIRTIO_SND_S_IO_ERR
+};
+
+/* common header */
+struct virtio_snd_hdr {
+	__le32 code;
+};
+
+/* event notification */
+struct virtio_snd_event {
+	/* VIRTIO_SND_EVT_XXX */
+	struct virtio_snd_hdr hdr;
+	/* optional event data */
+	__le32 data;
+};
+
+/* common control request to query an item information */
+struct virtio_snd_query_info {
+	/* VIRTIO_SND_R_XXX_INFO */
+	struct virtio_snd_hdr hdr;
+	/* item start identifier */
+	__le32 start_id;
+	/* item count to query */
+	__le32 count;
+	/* item information size in bytes */
+	__le32 size;
+};
+
+/* common item information header */
+struct virtio_snd_info {
+	/* function group node id (High Definition Audio Specification 7.1.2) */
+	__le32 hda_fn_nid;
+};
+
+/*******************************************************************************
+ * JACK CONTROL MESSAGES
+ */
+struct virtio_snd_jack_hdr {
+	/* VIRTIO_SND_R_JACK_XXX */
+	struct virtio_snd_hdr hdr;
+	/* 0 ... virtio_snd_config::jacks - 1 */
+	__le32 jack_id;
+};
+
+/* supported jack features */
+enum {
+	VIRTIO_SND_JACK_F_REMAP = 0
+};
+
+struct virtio_snd_jack_info {
+	/* common header */
+	struct virtio_snd_info hdr;
+	/* supported feature bit map (1 << VIRTIO_SND_JACK_F_XXX) */
+	__le32 features;
+	/* pin configuration (High Definition Audio Specification 7.3.3.31) */
+	__le32 hda_reg_defconf;
+	/* pin capabilities (High Definition Audio Specification 7.3.4.9) */
+	__le32 hda_reg_caps;
+	/* current jack connection status (0: disconnected, 1: connected) */
+	__u8 connected;
+
+	__u8 padding[7];
+};
+
+/* jack remapping control request */
+struct virtio_snd_jack_remap {
+	/* .code = VIRTIO_SND_R_JACK_REMAP */
+	struct virtio_snd_jack_hdr hdr;
+	/* selected association number */
+	__le32 association;
+	/* selected sequence number */
+	__le32 sequence;
+};
+
+/*******************************************************************************
+ * PCM CONTROL MESSAGES
+ */
+struct virtio_snd_pcm_hdr {
+	/* VIRTIO_SND_R_PCM_XXX */
+	struct virtio_snd_hdr hdr;
+	/* 0 ... virtio_snd_config::streams - 1 */
+	__le32 stream_id;
+};
+
+/* supported PCM stream features */
+enum {
+	VIRTIO_SND_PCM_F_SHMEM_HOST = 0,
+	VIRTIO_SND_PCM_F_SHMEM_GUEST,
+	VIRTIO_SND_PCM_F_MSG_POLLING,
+	VIRTIO_SND_PCM_F_EVT_SHMEM_PERIODS,
+	VIRTIO_SND_PCM_F_EVT_XRUNS
+};
+
+/* supported PCM sample formats */
+enum {
+	/* analog formats (width / physical width) */
+	VIRTIO_SND_PCM_FMT_IMA_ADPCM = 0,	/*  4 /  4 bits */
+	VIRTIO_SND_PCM_FMT_MU_LAW,		/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_A_LAW,		/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_S8,			/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_U8,			/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_S16,			/* 16 / 16 bits */
+	VIRTIO_SND_PCM_FMT_U16,			/* 16 / 16 bits */
+	VIRTIO_SND_PCM_FMT_S18_3,		/* 18 / 24 bits */
+	VIRTIO_SND_PCM_FMT_U18_3,		/* 18 / 24 bits */
+	VIRTIO_SND_PCM_FMT_S20_3,		/* 20 / 24 bits */
+	VIRTIO_SND_PCM_FMT_U20_3,		/* 20 / 24 bits */
+	VIRTIO_SND_PCM_FMT_S24_3,		/* 24 / 24 bits */
+	VIRTIO_SND_PCM_FMT_U24_3,		/* 24 / 24 bits */
+	VIRTIO_SND_PCM_FMT_S20,			/* 20 / 32 bits */
+	VIRTIO_SND_PCM_FMT_U20,			/* 20 / 32 bits */
+	VIRTIO_SND_PCM_FMT_S24,			/* 24 / 32 bits */
+	VIRTIO_SND_PCM_FMT_U24,			/* 24 / 32 bits */
+	VIRTIO_SND_PCM_FMT_S32,			/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_U32,			/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_FLOAT,		/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_FLOAT64,		/* 64 / 64 bits */
+	/* digital formats (width / physical width) */
+	VIRTIO_SND_PCM_FMT_DSD_U8,		/*  8 /  8 bits */
+	VIRTIO_SND_PCM_FMT_DSD_U16,		/* 16 / 16 bits */
+	VIRTIO_SND_PCM_FMT_DSD_U32,		/* 32 / 32 bits */
+	VIRTIO_SND_PCM_FMT_IEC958_SUBFRAME	/* 32 / 32 bits */
+};
+
+/* supported PCM frame rates */
+enum {
+	VIRTIO_SND_PCM_RATE_5512 = 0,
+	VIRTIO_SND_PCM_RATE_8000,
+	VIRTIO_SND_PCM_RATE_11025,
+	VIRTIO_SND_PCM_RATE_16000,
+	VIRTIO_SND_PCM_RATE_22050,
+	VIRTIO_SND_PCM_RATE_32000,
+	VIRTIO_SND_PCM_RATE_44100,
+	VIRTIO_SND_PCM_RATE_48000,
+	VIRTIO_SND_PCM_RATE_64000,
+	VIRTIO_SND_PCM_RATE_88200,
+	VIRTIO_SND_PCM_RATE_96000,
+	VIRTIO_SND_PCM_RATE_176400,
+	VIRTIO_SND_PCM_RATE_192000,
+	VIRTIO_SND_PCM_RATE_384000
+};
+
+struct virtio_snd_pcm_info {
+	/* common header */
+	struct virtio_snd_info hdr;
+	/* supported feature bit map (1 << VIRTIO_SND_PCM_F_XXX) */
+	__le32 features;
+	/* supported sample format bit map (1 << VIRTIO_SND_PCM_FMT_XXX) */
+	__le64 formats;
+	/* supported frame rate bit map (1 << VIRTIO_SND_PCM_RATE_XXX) */
+	__le64 rates;
+	/* dataflow direction (VIRTIO_SND_D_XXX) */
+	__u8 direction;
+	/* minimum # of supported channels */
+	__u8 channels_min;
+	/* maximum # of supported channels */
+	__u8 channels_max;
+
+	__u8 padding[5];
+};
+
+/* set PCM stream format */
+struct virtio_snd_pcm_set_params {
+	/* .code = VIRTIO_SND_R_PCM_SET_PARAMS */
+	struct virtio_snd_pcm_hdr hdr;
+	/* size of the hardware buffer */
+	__le32 buffer_bytes;
+	/* size of the hardware period */
+	__le32 period_bytes;
+	/* selected feature bit map (1 << VIRTIO_SND_PCM_F_XXX) */
+	__le32 features;
+	/* selected # of channels */
+	__u8 channels;
+	/* selected sample format (VIRTIO_SND_PCM_FMT_XXX) */
+	__u8 format;
+	/* selected frame rate (VIRTIO_SND_PCM_RATE_XXX) */
+	__u8 rate;
+
+	__u8 padding;
+};
+
+/*******************************************************************************
+ * PCM I/O MESSAGES
+ */
+
+/* I/O request header */
+struct virtio_snd_pcm_xfer {
+	/* 0 ... virtio_snd_config::streams - 1 */
+	__le32 stream_id;
+};
+
+/* I/O request status */
+struct virtio_snd_pcm_status {
+	/* VIRTIO_SND_S_XXX */
+	__le32 status;
+	/* current device latency */
+	__le32 latency_bytes;
+};
+
+/*******************************************************************************
+ * CHANNEL MAP CONTROL MESSAGES
+ */
+struct virtio_snd_chmap_hdr {
+	/* VIRTIO_SND_R_CHMAP_XXX */
+	struct virtio_snd_hdr hdr;
+	/* 0 ... virtio_snd_config::chmaps - 1 */
+	__le32 chmap_id;
+};
+
+/* standard channel position definition */
+enum {
+	VIRTIO_SND_CHMAP_NONE = 0,	/* undefined */
+	VIRTIO_SND_CHMAP_NA,		/* silent */
+	VIRTIO_SND_CHMAP_MONO,		/* mono stream */
+	VIRTIO_SND_CHMAP_FL,		/* front left */
+	VIRTIO_SND_CHMAP_FR,		/* front right */
+	VIRTIO_SND_CHMAP_RL,		/* rear left */
+	VIRTIO_SND_CHMAP_RR,		/* rear right */
+	VIRTIO_SND_CHMAP_FC,		/* front center */
+	VIRTIO_SND_CHMAP_LFE,		/* low frequency (LFE) */
+	VIRTIO_SND_CHMAP_SL,		/* side left */
+	VIRTIO_SND_CHMAP_SR,		/* side right */
+	VIRTIO_SND_CHMAP_RC,		/* rear center */
+	VIRTIO_SND_CHMAP_FLC,		/* front left center */
+	VIRTIO_SND_CHMAP_FRC,		/* front right center */
+	VIRTIO_SND_CHMAP_RLC,		/* rear left center */
+	VIRTIO_SND_CHMAP_RRC,		/* rear right center */
+	VIRTIO_SND_CHMAP_FLW,		/* front left wide */
+	VIRTIO_SND_CHMAP_FRW,		/* front right wide */
+	VIRTIO_SND_CHMAP_FLH,		/* front left high */
+	VIRTIO_SND_CHMAP_FCH,		/* front center high */
+	VIRTIO_SND_CHMAP_FRH,		/* front right high */
+	VIRTIO_SND_CHMAP_TC,		/* top center */
+	VIRTIO_SND_CHMAP_TFL,		/* top front left */
+	VIRTIO_SND_CHMAP_TFR,		/* top front right */
+	VIRTIO_SND_CHMAP_TFC,		/* top front center */
+	VIRTIO_SND_CHMAP_TRL,		/* top rear left */
+	VIRTIO_SND_CHMAP_TRR,		/* top rear right */
+	VIRTIO_SND_CHMAP_TRC,		/* top rear center */
+	VIRTIO_SND_CHMAP_TFLC,		/* top front left center */
+	VIRTIO_SND_CHMAP_TFRC,		/* top front right center */
+	VIRTIO_SND_CHMAP_TSL,		/* top side left */
+	VIRTIO_SND_CHMAP_TSR,		/* top side right */
+	VIRTIO_SND_CHMAP_LLFE,		/* left LFE */
+	VIRTIO_SND_CHMAP_RLFE,		/* right LFE */
+	VIRTIO_SND_CHMAP_BC,		/* bottom center */
+	VIRTIO_SND_CHMAP_BLC,		/* bottom left center */
+	VIRTIO_SND_CHMAP_BRC		/* bottom right center */
+};
+
+/* maximum possible number of channels */
+#define VIRTIO_SND_CHMAP_MAX_SIZE	18
+
+struct virtio_snd_chmap_info {
+	/* common header */
+	struct virtio_snd_info hdr;
+	/* dataflow direction (VIRTIO_SND_D_XXX) */
+	__u8 direction;
+	/* # of valid channel position values */
+	__u8 channels;
+	/* channel position values (VIRTIO_SND_CHMAP_XXX) */
+	__u8 positions[VIRTIO_SND_CHMAP_MAX_SIZE];
+};
+
+#endif /* VIRTIO_SND_IF_H */

@@ -99,6 +99,8 @@ source "sound/synth/Kconfig"
 
 source "sound/xen/Kconfig"
 
+source "sound/virtio/Kconfig"
+
 endif # SND
 
 endif # !UML

@@ -5,7 +5,8 @@
 obj-$(CONFIG_SOUND) += soundcore.o
 obj-$(CONFIG_DMASOUND) += oss/dmasound/
 obj-$(CONFIG_SND) += core/ i2c/ drivers/ isa/ pci/ ppc/ arm/ sh/ synth/ usb/ \
-	firewire/ sparc/ spi/ parisc/ pcmcia/ mips/ soc/ atmel/ hda/ x86/ xen/
+	firewire/ sparc/ spi/ parisc/ pcmcia/ mips/ soc/ atmel/ hda/ x86/ xen/ \
+	virtio/
 obj-$(CONFIG_SND_AOA) += aoa/
 
 # This one must be compilable even if sound is configured out

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Sound card driver for virtio
+
+config SND_VIRTIO
+	tristate "Virtio sound driver"
+	depends on VIRTIO
+	select SND_PCM
+	select SND_JACK
+	help
+          This is the virtual sound driver for virtio. Say Y or M.

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
+
+virtio_snd-objs := \
+	virtio_card.o
+