openamp: add new ops wait_notified() to avoid looping in tx buffer get

Give users a chance to handle the no tx buffer situation when get tx buffer,
with this patch, user can call rproc_virtio_set_wait_notified() to set the
wait_notified() callback and this callback function will be called
when no tx buffer in tx virtqueue.

Signed-off-by: Guiding Li <[email protected]>
Signed-off-by: Bowen Wang <[email protected]>

lib/include/openamp/remoteproc.h

@@ -462,6 +462,17 @@ struct remoteproc_ops {
 	/** Notify the remote */
 	int (*notify)(struct remoteproc *rproc, uint32_t id);
 
+	/**
+	 * @brief Wait for remote notified, when there is no TX buffer anymore.
+	 * Set to NULL means use usleep to wait TX buffer available.
+	 *
+	 * @param rproc		pointer to remoteproc instance
+	 * @param id		the notifyid
+	 *
+	 * return 0 means there is notify available, otherwise negative value.
+	 */
+	int (*wait_notified)(struct remoteproc *rproc, uint32_t id);
+
 	/**
 	 * @brief Get remoteproc memory I/O region by either name, virtual
 	 * address, physical address or device address.

lib/include/openamp/remoteproc_virtio.h

@@ -39,6 +39,12 @@ extern "C" {
 /* define vdev notification function user should implement */
 typedef int (*rpvdev_notify_func)(void *priv, uint32_t id);
 
+/* define vdev wait notified function, user can implement this
+ * function to wait peer return the tx buffer when no tx buffer found,
+ * and this is optional
+ */
+typedef int (*rpvdev_wait_notified_func)(void *priv, uint32_t id);
+
 /** @brief Virtio structure for remoteproc instance */
 struct remoteproc_virtio {
 	/** Pointer to private data */
@@ -53,6 +59,9 @@ struct remoteproc_virtio {
 	/** Notification function */
 	rpvdev_notify_func notify;
 
+	/** Wait notification function */
+	rpvdev_wait_notified_func wait_notified;
+
 	/** Virtio device */
 	struct virtio_device vdev;
 
@@ -126,6 +135,19 @@ int rproc_virtio_notified(struct virtio_device *vdev, uint32_t notifyid);
  */
 void rproc_virtio_wait_remote_ready(struct virtio_device *vdev);
 
+/**
+ * @brief set the remoteproc virtio notified function, this function will be
+ * called when no tx buffer to let user to handle the customisze buffer wait
+ * function.
+ *
+ * @param vdev		Pointer to the virtio device
+ * @param wait_notified	The wait notified callback function
+ *
+ * @return 0 for successful, negative value for failure
+ */
+int rproc_virtio_set_wait_notified(struct virtio_device *vdev,
+				   rpvdev_wait_notified_func wait_notified);
+
 #if defined __cplusplus
 }
 #endif

lib/include/openamp/rpmsg_virtio.h

@@ -165,6 +165,15 @@ rpmsg_virtio_create_virtqueues(struct rpmsg_virtio_device *rvdev,
 					callbacks, NULL);
 }
 
+static inline int
+rpmsg_virtio_wait_notified(struct rpmsg_virtio_device *rvdev,
+			   struct virtqueue *vq)
+{
+	return rvdev->vdev->func->wait_notified ?
+	       rvdev->vdev->func->wait_notified(rvdev->vdev, vq) :
+	       RPMSG_ERR_PERM;
+}
+
 /**
  * @brief Get rpmsg virtio buffer size
  *

lib/include/openamp/virtio.h

@@ -231,6 +231,7 @@ struct virtio_dispatch {
 			     void *src, int length);
 	void (*reset_device)(struct virtio_device *dev);
 	void (*notify)(struct virtqueue *vq);
+	int (*wait_notified)(struct virtio_device *dev, struct virtqueue *vq);
 };
 
 /**

lib/remoteproc/remoteproc.c

@@ -900,6 +900,16 @@ static int remoteproc_virtio_notify(void *priv, uint32_t id)
 	return 0;
 }
 
+static int remoteproc_virtio_wait_notified(void *priv, uint32_t id)
+{
+	struct remoteproc *rproc = priv;
+
+	if (rproc->ops->wait_notified)
+		return rproc->ops->wait_notified(rproc, id);
+
+	return 0;
+}
+
 struct virtio_device *
 remoteproc_create_virtio(struct remoteproc *rproc,
 			 int vdev_id, unsigned int role,
@@ -958,6 +968,7 @@ remoteproc_create_virtio(struct remoteproc *rproc,
 	rproc_virtio_wait_remote_ready(vdev);
 
 	rpvdev = metal_container_of(vdev, struct remoteproc_virtio, vdev);
+	rpvdev->wait_notified = remoteproc_virtio_wait_notified;
 	metal_list_add_tail(&rproc->vdevs, &rpvdev->node);
 	num_vrings = vdev_rsc->num_of_vrings;
 

lib/remoteproc/remoteproc_virtio.c

@@ -30,6 +30,19 @@ static void rproc_virtio_virtqueue_notify(struct virtqueue *vq)
 	rpvdev->notify(rpvdev->priv, vring_info->notifyid);
 }
 
+static int rproc_virtio_wait_notified(struct virtio_device *vdev,
+				      struct virtqueue *vq)
+{
+	struct remoteproc_virtio *rpvdev;
+	struct virtio_vring_info *vring_info;
+	unsigned int vq_id = vq->vq_queue_index;
+
+	rpvdev = metal_container_of(vdev, struct remoteproc_virtio, vdev);
+	vring_info = &vdev->vrings_info[vq_id];
+
+	return rpvdev->wait_notified(rpvdev->priv, vring_info->notifyid);
+}
+
 static unsigned char rproc_virtio_get_status(struct virtio_device *vdev)
 {
 	struct remoteproc_virtio *rpvdev;
@@ -187,6 +200,7 @@ static const struct virtio_dispatch remoteproc_virtio_dispatch_funcs = {
 	.get_features = rproc_virtio_get_features,
 	.read_config = rproc_virtio_read_config,
 	.notify = rproc_virtio_virtqueue_notify,
+	.wait_notified = rproc_virtio_wait_notified,
 #ifndef VIRTIO_DEVICE_ONLY
 	/*
 	 * We suppose here that the vdev is in a shared memory so that can
@@ -364,3 +378,15 @@ void rproc_virtio_wait_remote_ready(struct virtio_device *vdev)
 		metal_cpu_yield();
 	}
 }
+
+int rproc_virtio_set_wait_notified(struct virtio_device *vdev,
+				   rpvdev_wait_notified_func wait_notified)
+{
+	struct remoteproc_virtio *rpvdev;
+
+	if (!vdev || !wait_notified)
+		return -RPROC_EINVAL;
+	rpvdev = metal_container_of(vdev, struct remoteproc_virtio, vdev);
+	rpvdev->wait_notified = wait_notified;
+	return 0;
+}

lib/rpmsg/rpmsg_virtio.c

@@ -376,6 +376,11 @@ static void *rpmsg_virtio_get_tx_payload_buffer(struct rpmsg_device *rdev,
 		metal_mutex_release(&rdev->lock);
 		if (rp_hdr || !tick_count)
 			break;
+
+		status = rpmsg_virtio_wait_notified(rvdev, rvdev->rvq);
+		if (status == RPMSG_SUCCESS)
+			continue;
+
 		metal_sleep_usec(RPMSG_TICKS_PER_INTERVAL);
 		tick_count--;
 	}