The control queue can be used by different parts of the driver to send
commands to the device. Control messages can be either synchronous or
asynchronous. The lifetime of a message is controlled by a reference
count.
Introduce a module parameter to set the message completion timeout:
msg_timeout_ms [=1000]
Signed-off-by: Anton Yakovlev <anton.yakovlev@xxxxxxxxxxxxxxx>
---
sound/virtio/Makefile | 3 +-
sound/virtio/virtio_card.c | 13 ++
sound/virtio/virtio_card.h | 7 +
sound/virtio/virtio_ctl_msg.c | 310 ++++++++++++++++++++++++++++++++++
sound/virtio/virtio_ctl_msg.h | 78 +++++++++
5 files changed, 410 insertions(+), 1 deletion(-)
create mode 100644 sound/virtio/virtio_ctl_msg.c
create mode 100644 sound/virtio/virtio_ctl_msg.h
diff --git a/sound/virtio/Makefile b/sound/virtio/Makefile
index 8c87ebb9982b..dc551e637441 100644
--- a/sound/virtio/Makefile
+++ b/sound/virtio/Makefile
@@ -3,5 +3,6 @@
obj-$(CONFIG_SND_VIRTIO) += virtio_snd.o
virtio_snd-objs := \
- virtio_card.o
+ virtio_card.o \
+ virtio_ctl_msg.o
diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
index 697cb5f16e4d..196cb97087b0 100644
--- a/sound/virtio/virtio_card.c
+++ b/sound/virtio/virtio_card.c
@@ -11,6 +11,10 @@
#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);
/**
@@ -82,6 +86,7 @@ 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] = {
@@ -193,6 +198,11 @@ 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;
}
@@ -214,6 +224,7 @@ static int virtsnd_probe(struct virtio_device *vdev)
return -ENOMEM;
snd->vdev = vdev;
+ INIT_LIST_HEAD(&snd->ctl_msgs);
vdev->priv = snd;
@@ -249,6 +260,8 @@ static void virtsnd_remove(struct virtio_device *vdev)
{
struct virtio_snd *snd = vdev->priv;
+ virtsnd_ctl_msg_cancel_all(snd);
+
if (snd->card)
snd_card_free(snd->card);
diff --git a/sound/virtio/virtio_card.h b/sound/virtio/virtio_card.h
index b903b1b12e90..349311a30199 100644
--- a/sound/virtio/virtio_card.h
+++ b/sound/virtio/virtio_card.h
@@ -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 int msg_timeout_ms;
+
static inline struct virtio_snd_queue *
virtsnd_control_queue(struct virtio_snd *snd)
{
diff --git a/sound/virtio/virtio_ctl_msg.c b/sound/virtio/virtio_ctl_msg.c
new file mode 100644
index 000000000000..67a5a0301ba3
--- /dev/null
+++ b/sound/virtio/virtio_ctl_msg.c
@@ -0,0 +1,310 @@
+// 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(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);
+}
diff --git a/sound/virtio/virtio_ctl_msg.h b/sound/virtio/virtio_ctl_msg.h
new file mode 100644
index 000000000000..7f4db044f28e
--- /dev/null
+++ b/sound/virtio/virtio_ctl_msg.h
@@ -0,0 +1,78 @@
+/* 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 */
--
2.30.1
