1 files changed, 308 insertions, 0 deletions
diff --git a/sound/virtio/virtio_ctl_msg.c b/sound/virtio/virtio_ctl_msg.c
new file mode 100644
index 000000000000..9dabea01277f
--- /dev/null
+++ b/sound/virtio/virtio_ctl_msg.c
@@ -0,0 +1,308 @@
+// 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_response() - 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);
+	} while (!virtqueue_enable_cb(vqueue));
+	spin_unlock_irqrestore(&queue->lock, flags);
+}