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From:   Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
To:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Ohad Ben-Cohen <ohad@wizery.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>
CC:     <linux-remoteproc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <julien.massot@iot.bzh>, <arnaud.pouliquen@foss.st.com>
Subject: [PATCH 1/4] rpmsg: Introduce rpmsg_create_default_ept function
Date:   Mon, 7 Jun 2021 19:30:29 +0200
Message-ID: <20210607173032.30133-2-arnaud.pouliquen@foss.st.com>
In-Reply-To: <20210607173032.30133-1-arnaud.pouliquen@foss.st.com>
References: <20210607173032.30133-1-arnaud.pouliquen@foss.st.com>
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The rpmsg devices can be probed without default endpoint. This function
provides the capability for rpmsg drivers to create a default endpoint
on runtime.

For example, a driver might want the rpmsg core dispatcher to drop its
messages until it is ready to process them. In this case, the driver will
create the default endpoint when the conditions are met to process the
messages.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
---
 drivers/rpmsg/rpmsg_core.c | 51 ++++++++++++++++++++++++++++++++++++++
 include/linux/rpmsg.h      | 14 +++++++++++
 2 files changed, 65 insertions(+)

diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index e5daee4f9373..07b680bda61f 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -115,6 +115,57 @@ struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev,
 }
 EXPORT_SYMBOL(rpmsg_create_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 the default endpoint if already created or creates
+ * a endpoint and assign it 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).
+ *
+ * Returns 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;
+
+	/* 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_destroy_ept() - destroy an existing rpmsg endpoint
  * @ept: endpoing to destroy
diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
index d97dcd049f18..ab034061722c 100644
--- a/include/linux/rpmsg.h
+++ b/include/linux/rpmsg.h
@@ -172,6 +172,9 @@ void rpmsg_destroy_ept(struct rpmsg_endpoint *);
 struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *,
 					rpmsg_rx_cb_t cb, void *priv,
 					struct rpmsg_channel_info chinfo);
+struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
+						rpmsg_rx_cb_t cb, void *priv,
+						struct rpmsg_channel_info chinfo);
 
 int rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len);
 int rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst);
@@ -234,6 +237,17 @@ static inline struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev
 	return ERR_PTR(-ENXIO);
 }
 
+static inline struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
+							      rpmsg_rx_cb_t cb,
+							      void *priv,
+							      struct rpmsg_channel_info chinfo)
+{
+	/* This shouldn't be possible */
+	WARN_ON(1);
+
+	return NULL;
+}
+
 static inline int rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len)
 {
 	/* This shouldn't be possible */
-- 
2.17.1