ALSA: virtio: handling control messages (9d45e514) · Commits · github.com / kvm-riscv / linux

sound/virtio/Makefile

+2 −1

Original line number	Diff line number	Diff line
		@@ -3,5 +3,6 @@
		obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o

		virtio_snd-objs := \
		virtio_card.o
		virtio_card.o \
		virtio_ctl_msg.o

sound/virtio/virtio_card.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -11,6 +11,10 @@

		#include "virtio_card.h"

		u32 virtsnd_msg_timeout_ms = MSEC_PER_SEC;
		module_param_named(msg_timeout_ms, virtsnd_msg_timeout_ms, uint, 0644);
		MODULE_PARM_DESC(msg_timeout_ms, "Message completion timeout in milliseconds");

		static void virtsnd_remove(struct virtio_device *vdev);

		/**
		@@ -96,9 +100,11 @@ 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
		};
		static const char *names[VIRTIO_SND_VQ_MAX] = {
		[VIRTIO_SND_VQ_CONTROL] = "virtsnd-ctl",
		[VIRTIO_SND_VQ_EVENT] = "virtsnd-event"
		};
		struct virtqueue *vqs[VIRTIO_SND_VQ_MAX] = { 0 };
		@@ -226,6 +232,11 @@ static int virtsnd_validate(struct virtio_device *vdev)
		return -EINVAL;
		}

		if (!virtsnd_msg_timeout_ms) {
		dev_err(&vdev->dev, "msg_timeout_ms value cannot be zero\n");
		return -EINVAL;
		}

		return 0;
		}

		@@ -247,6 +258,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
		return -ENOMEM;

		snd->vdev = vdev;
		INIT_LIST_HEAD(&snd->ctl_msgs);

		vdev->priv = snd;

		@@ -283,6 +295,7 @@ static void virtsnd_remove(struct virtio_device *vdev)
		struct virtio_snd *snd = vdev->priv;

		virtsnd_disable_event_vq(snd);
		virtsnd_ctl_msg_cancel_all(snd);

		if (snd->card)
		snd_card_free(snd->card);

sound/virtio/virtio_card.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -11,6 +11,8 @@
		#include <sound/core.h>
		#include <uapi/linux/virtio_snd.h>

		#include "virtio_ctl_msg.h"

		#define VIRTIO_SND_CARD_DRIVER "virtio-snd"
		#define VIRTIO_SND_CARD_NAME "VirtIO SoundCard"

		@@ -29,15 +31,20 @@ struct virtio_snd_queue {
		* @vdev: Underlying virtio device.
		* @queues: Virtqueue wrappers.
		* @card: ALSA sound card.
		* @ctl_msgs: Pending control request list.
		* @event_msgs: Device events.
		*/
		struct virtio_snd {
		struct virtio_device *vdev;
		struct virtio_snd_queue queues[VIRTIO_SND_VQ_MAX];
		struct snd_card *card;
		struct list_head ctl_msgs;
		struct virtio_snd_event *event_msgs;
		};

		/* Message completion timeout in milliseconds (module parameter). */
		extern u32 virtsnd_msg_timeout_ms;

		static inline struct virtio_snd_queue *
		virtsnd_control_queue(struct virtio_snd *snd)
		{

sound/virtio/virtio_ctl_msg.c

0 → 100644

+310 −0

Original line number	Diff line number	Diff line
		// 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"

		/**
		* struct virtio_snd_msg - Control message.
		* @sg_request: Scattergather list containing a device request (header).
		* @sg_response: Scattergather list containing a device response (status).
		* @list: Pending message list entry.
		* @notify: Request completed notification.
		* @ref_count: Reference count used to manage a message lifetime.
		*/
		struct virtio_snd_msg {
		struct scatterlist sg_request;
		struct scatterlist sg_response;
		struct list_head list;
		struct completion notify;
		refcount_t ref_count;
		};

		/**
		* virtsnd_ctl_msg_ref() - Increment reference counter for the message.
		* @msg: Control message.
		*
		* Context: Any context.
		*/
		void virtsnd_ctl_msg_ref(struct virtio_snd_msg *msg)
		{
		refcount_inc(&msg->ref_count);
		}

		/**
		* virtsnd_ctl_msg_unref() - Decrement reference counter for the message.
		* @msg: Control message.
		*
		* The message will be freed when the ref_count value is 0.
		*
		* Context: Any context.
		*/
		void virtsnd_ctl_msg_unref(struct virtio_snd_msg *msg)
		{
		if (refcount_dec_and_test(&msg->ref_count))
		kfree(msg);
		}

		/**
		* virtsnd_ctl_msg_request() - Get a pointer to the request header.
		* @msg: Control message.
		*
		* Context: Any context.
		*/
		void virtsnd_ctl_msg_request(struct virtio_snd_msg msg)
		{
		return sg_virt(&msg->sg_request);
		}

		/**
		* virtsnd_ctl_msg_request() - Get a pointer to the response header.
		* @msg: Control message.
		*
		* Context: Any context.
		*/
		void virtsnd_ctl_msg_response(struct virtio_snd_msg msg)
		{
		return sg_virt(&msg->sg_response);
		}

		/**
		* virtsnd_ctl_msg_alloc() - Allocate and initialize a control message.
		* @request_size: Size of request header.
		* @response_size: Size of 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, NULL on failure.
		*/
		struct virtio_snd_msg *virtsnd_ctl_msg_alloc(size_t request_size,
		size_t response_size, gfp_t gfp)
		{
		struct virtio_snd_msg *msg;

		if (!request_size \|\| !response_size)
		return NULL;

		msg = kzalloc(sizeof(*msg) + request_size + response_size, gfp);
		if (!msg)
		return NULL;

		sg_init_one(&msg->sg_request, (u8 )msg + sizeof(msg), request_size);
		sg_init_one(&msg->sg_response, (u8 )msg + sizeof(msg) + request_size,
		response_size);

		INIT_LIST_HEAD(&msg->list);
		init_completion(&msg->notify);
		/* This reference is dropped in virtsnd_ctl_msg_complete(). */
		refcount_set(&msg->ref_count, 1);

		return msg;
		}

		/**
		* virtsnd_ctl_msg_send() - Send a control message.
		* @snd: VirtIO sound device.
		* @msg: Control message.
		* @out_sgs: Additional sg-list to attach to the request header (may be NULL).
		* @in_sgs: Additional sg-list to attach to the response header (may be NULL).
		* @nowait: Flag indicating whether to wait for completion.
		*
		* Context: Any context. Takes and releases the control queue spinlock.
		* May sleep if @nowait is false.
		* Return: 0 on success, -errno on failure.
		*/
		int virtsnd_ctl_msg_send(struct virtio_snd snd, struct virtio_snd_msg msg,
		struct scatterlist *out_sgs,
		struct scatterlist *in_sgs, bool nowait)
		{
		struct virtio_device *vdev = snd->vdev;
		struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
		unsigned int js = msecs_to_jiffies(virtsnd_msg_timeout_ms);
		struct virtio_snd_hdr *request = virtsnd_ctl_msg_request(msg);
		struct virtio_snd_hdr *response = virtsnd_ctl_msg_response(msg);
		unsigned int nouts = 0;
		unsigned int nins = 0;
		struct scatterlist *psgs[4];
		bool notify = false;
		unsigned long flags;
		int rc;

		virtsnd_ctl_msg_ref(msg);

		/* Set the default status in case the message was canceled. */
		response->code = cpu_to_le32(VIRTIO_SND_S_IO_ERR);

		psgs[nouts++] = &msg->sg_request;
		if (out_sgs)
		psgs[nouts++] = out_sgs;

		psgs[nouts + nins++] = &msg->sg_response;
		if (in_sgs)
		psgs[nouts + nins++] = in_sgs;

		spin_lock_irqsave(&queue->lock, flags);
		rc = virtqueue_add_sgs(queue->vqueue, psgs, nouts, nins, 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) {
		dev_err(&vdev->dev, "failed to send control message (0x%08x)\n",
		le32_to_cpu(request->code));

		/*
		* Since in this case virtsnd_ctl_msg_complete() will not be
		* called, it is necessary to decrement the reference count.
		*/
		virtsnd_ctl_msg_unref(msg);

		goto on_exit;
		}

		if (notify)
		virtqueue_notify(queue->vqueue);

		if (nowait)
		goto on_exit;

		rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
		if (rc <= 0) {
		if (!rc) {
		dev_err(&vdev->dev,
		"control message (0x%08x) timeout\n",
		le32_to_cpu(request->code));
		rc = -ETIMEDOUT;
		}

		goto on_exit;
		}

		switch (le32_to_cpu(response->code)) {
		case VIRTIO_SND_S_OK:
		rc = 0;
		break;
		case VIRTIO_SND_S_NOT_SUPP:
		rc = -EOPNOTSUPP;
		break;
		case VIRTIO_SND_S_IO_ERR:
		rc = -EIO;
		break;
		default:
		rc = -EINVAL;
		break;
		}

		on_exit:
		virtsnd_ctl_msg_unref(msg);

		return rc;
		}

		/**
		* virtsnd_ctl_msg_complete() - Complete a control message.
		* @msg: Control message.
		*
		* Context: Any context. Expects the control queue spinlock to be held by
		* caller.
		*/
		void virtsnd_ctl_msg_complete(struct virtio_snd_msg *msg)
		{
		list_del(&msg->list);
		complete(&msg->notify);

		virtsnd_ctl_msg_unref(msg);
		}

		/**
		* virtsnd_ctl_msg_cancel_all() - Cancel all pending control messages.
		* @snd: VirtIO sound device.
		*
		* Context: Any context.
		*/
		void virtsnd_ctl_msg_cancel_all(struct virtio_snd *snd)
		{
		struct virtio_snd_queue *queue = virtsnd_control_queue(snd);
		unsigned long flags;

		spin_lock_irqsave(&queue->lock, flags);
		while (!list_empty(&snd->ctl_msgs)) {
		struct virtio_snd_msg *msg =
		list_first_entry(&snd->ctl_msgs, struct virtio_snd_msg,
		list);

		virtsnd_ctl_msg_complete(msg);
		}
		spin_unlock_irqrestore(&queue->lock, flags);
		}

		/**
		* 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_snd_msg *msg;
		struct virtio_snd_query_info *query;
		struct scatterlist sg;

		msg = virtsnd_ctl_msg_alloc(sizeof(*query),
		sizeof(struct virtio_snd_hdr), GFP_KERNEL);
		if (!msg)
		return -ENOMEM;

		query = virtsnd_ctl_msg_request(msg);
		query->hdr.code = cpu_to_le32(command);
		query->start_id = cpu_to_le32(start_id);
		query->count = cpu_to_le32(count);
		query->size = cpu_to_le32(size);

		sg_init_one(&sg, info, count * size);

		return virtsnd_ctl_msg_send(snd, msg, NULL, &sg, false);
		}

		/**
		* 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);
		struct virtio_snd_msg *msg;
		u32 length;
		unsigned long flags;

		spin_lock_irqsave(&queue->lock, flags);
		do {
		virtqueue_disable_cb(vqueue);
		while ((msg = virtqueue_get_buf(vqueue, &length)))
		virtsnd_ctl_msg_complete(msg);
		if (unlikely(virtqueue_is_broken(vqueue)))
		break;
		} while (!virtqueue_enable_cb(vqueue));
		spin_unlock_irqrestore(&queue->lock, flags);
		}

sound/virtio/virtio_ctl_msg.h

0 → 100644

+78 −0

Original line number	Diff line number	Diff line
		/* SPDX-License-Identifier: GPL-2.0+ */
		/*
		* virtio-snd: Virtio sound device
		* Copyright (C) 2021 OpenSynergy GmbH
		*/
		#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;

		void virtsnd_ctl_msg_ref(struct virtio_snd_msg *msg);

		void virtsnd_ctl_msg_unref(struct virtio_snd_msg *msg);

		void virtsnd_ctl_msg_request(struct virtio_snd_msg msg);

		void virtsnd_ctl_msg_response(struct virtio_snd_msg msg);

		struct virtio_snd_msg *virtsnd_ctl_msg_alloc(size_t request_size,
		size_t response_size, gfp_t gfp);

		int virtsnd_ctl_msg_send(struct virtio_snd snd, struct virtio_snd_msg msg,
		struct scatterlist *out_sgs,
		struct scatterlist *in_sgs, bool nowait);

		/**
		* virtsnd_ctl_msg_send_sync() - Simplified sending of synchronous 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 that permits to sleep.
		* 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.
		*/
		static inline int virtsnd_ctl_msg_send_sync(struct virtio_snd *snd,
		struct virtio_snd_msg *msg)
		{
		return virtsnd_ctl_msg_send(snd, msg, NULL, NULL, false);
		}

		/**
		* virtsnd_ctl_msg_send_async() - Simplified sending of asynchronous message.
		* @snd: VirtIO sound device.
		* @msg: Control message.
		*
		* Context: Any context.
		* Return: 0 on success, -errno on failure.
		*/
		static inline int virtsnd_ctl_msg_send_async(struct virtio_snd *snd,
		struct virtio_snd_msg *msg)
		{
		return virtsnd_ctl_msg_send(snd, msg, NULL, NULL, true);
		}

		void virtsnd_ctl_msg_cancel_all(struct virtio_snd *snd);

		void virtsnd_ctl_msg_complete(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 */