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 to handle the wait when no tx buffer in tx virtqueue.

Signed-off-by: Guiding Li <liguiding1@xiaomi.com>
Signed-off-by: Bowen Wang <wangbowen6@xiaomi.com>

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.
@@ -497,6 +508,7 @@ struct remoteproc_ops {
 #define RPROC_ERR_RSC_TAB_NP          (RPROC_EBASE + 10)
 #define RPROC_ERR_RSC_TAB_NS          (RPROC_EBASE + 11)
 #define RPROC_ERR_LOADER_STATE (RPROC_EBASE + 12)
+#define RPROC_EOPNOTSUPP	(RPROC_EBASE + 13)
 #define RPROC_EMAX	(RPROC_EBASE + 16)
 #define RPROC_EPTR	(void *)(-1)
 #define RPROC_EOF	(void *)(-1)

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 available Tx buffers.
+ */
+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 (optional) */
+	rpvdev_wait_notified_func wait_notified;
+
 	/** Virtio device */
 	struct virtio_device vdev;
 
@@ -126,6 +135,20 @@ 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 wait notified function.
+ *
+ * This \ref wait_notified_cb function will be called to customize the wait, when
+ * no Tx buffer is available.
+ *
+ * @param vdev			Pointer to the virtio device.
+ * @param wait_notified_cb	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_cb);
+
 #if defined __cplusplus
 }
 #endif

lib/include/openamp/rpmsg.h

@@ -43,6 +43,7 @@ extern "C" {
 #define RPMSG_ERR_INIT			(RPMSG_ERROR_BASE - 6)
 #define RPMSG_ERR_ADDR			(RPMSG_ERROR_BASE - 7)
 #define RPMSG_ERR_PERM			(RPMSG_ERROR_BASE - 8)
+#define RPMSG_EOPNOTSUPP		(RPMSG_ERROR_BASE - 9)
 
 struct rpmsg_endpoint;
 struct rpmsg_device;

lib/include/openamp/virtio.h

@@ -275,6 +275,9 @@ struct virtio_dispatch {
 
 	/** Notify the other side that a virtio vring as been updated. */
 	void (*notify)(struct virtqueue *vq);
+
+	/** Customize the wait, when no Tx buffer is available (optional) */
+	int (*wait_notified)(struct virtio_device *dev, struct virtqueue *vq);
 };
 
 /**