[PATCH v7 08/12] rpmsg: Introduce rpmsg_create_default_ept function

[Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>]

By providing a callback in the rpmsg_driver structure, the rpmsg devices
can be probed with a default endpoint created.

In this case, it is not possible to associated to this endpoint private data
that could allow the driver to retrieve the context.

This helper function allows rpmsg drivers to create a default endpoint
on runtime with an associated private context.

For example, a driver might create a context structure on the probe and
want to provide that context as private data for the default rpmsg
callback.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Julien Massot <julien.massot@iot.bzh>

---
Update vs previous revision:
- move rpmsg_create_default_ept declaration from rpmsg.h to rpmsg_internal.h
- fix rpmsg_create_default_ept function header
- Treat rpdev->ept!= 0 as invalid usage with a WARN_ON
---
 drivers/rpmsg/rpmsg_core.c     | 54 ++++++++++++++++++++++++++++++++++
 drivers/rpmsg/rpmsg_internal.h |  4 +++
 2 files changed, 58 insertions(+)

diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index 45227c864aa2..bdcde57c22f6 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -133,6 +133,60 @@ void rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
 }
 EXPORT_SYMBOL(rpmsg_destroy_ept);
 
+/**
+ * rpmsg_create_default_ept() - create a default rpmsg_endpoint for a rpmsg device
+ * @rpdev: rpmsg channel device
+ * @cb: rx callback handler
+ * @priv: private data for the driver's use
+ * @chinfo: channel_info with the local rpmsg address to bind with @cb
+ *
+ * On register_rpmsg_driver if no callback is provided in the rpmsg_driver structure,
+ * no endpoint is created when the device is probed by the rpmsg bus.
+ *
+ * This function returns a pointer to an endpoint created and assigned as the default
+ * endpoint of the rpmsg device.
+ *
+ * Drivers should provide their @rpdev channel (so the new endpoint would belong
+ * to the same remote processor their channel belongs to), an rx callback
+ * function, an optional private data (which is provided back when the
+ * rx callback is invoked), and an address they want to bind with the
+ * callback. If @addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
+ * dynamically assign them an available rpmsg address (drivers should have
+ * a very good reason why not to always use RPMSG_ADDR_ANY here).
+ *
+ * Return: a pointer to the endpoint on success, or NULL on error.
+ */
+struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
+						rpmsg_rx_cb_t cb, void *priv,
+						struct rpmsg_channel_info chinfo)
+{
+	struct rpmsg_endpoint *ept;
+
+	if (WARN_ON(!rpdev))
+		return NULL;
+
+	if (WARN_ON(rpdev->ept))
+		return NULL;
+
+	/* It does not make sense to create a default endpoint without a callback. */
+	if (!cb)
+		return NULL;
+
+	if (rpdev->ept)
+		return rpdev->ept;
+
+	ept = rpdev->ops->create_ept(rpdev, cb, priv, chinfo);
+	if (!ept)
+		return NULL;
+
+	/* Assign the new endpoint as default endpoint */
+	rpdev->ept = ept;
+	rpdev->src = ept->addr;
+
+	return ept;
+}
+EXPORT_SYMBOL(rpmsg_create_default_ept);
+
 /**
  * rpmsg_send() - send a message across to the remote processor
  * @ept: the rpmsg endpoint
diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
index 8bb56d347c81..4577e9381d25 100644
--- a/drivers/rpmsg/rpmsg_internal.h
+++ b/drivers/rpmsg/rpmsg_internal.h
@@ -98,4 +98,8 @@ static inline int rpmsg_ctrldev_register_device(struct rpmsg_device *rpdev)
 	return rpmsg_register_device(rpdev);
 }
 
+struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
+						rpmsg_rx_cb_t cb, void *priv,
+						struct rpmsg_channel_info chinfo);
+
 #endif
-- 
2.17.1