linux-kernel - [PATCH v4 4/4] rpmsg: char: Introduce the "rpmsg-raw" channel

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Date:   Mon, 12 Jul 2021 15:19:00 +0200
From:   Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
CC:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <julien.massot@....bzh>, <arnaud.pouliquen@...s.st.com>
Subject: [PATCH v4 4/4] rpmsg: char: Introduce the "rpmsg-raw" channel

Allows to probe the endpoint device on a remote name service announcement,
by registering a rpmsg_driverfor the "rpmsg-raw" channel.

With this patch the /dev/rpmsgX interface can be instantiated by the remote
firmware.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Tested-by: Julien Massot <julien.massot@....bzh>
---
 drivers/rpmsg/rpmsg_char.c | 75 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 2 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index bd728d90ba4c..1b7b610e113d 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -25,6 +25,8 @@
 
 #include "rpmsg_char.h"
 
+#define RPMSG_CHAR_DEVNAME "rpmsg-raw"
+
 static dev_t rpmsg_major;
 static struct class *rpmsg_class;
 
@@ -421,6 +423,61 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent
 }
 EXPORT_SYMBOL(rpmsg_chrdev_eptdev_create);
 
+static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
+{
+	struct rpmsg_channel_info chinfo;
+	struct rpmsg_eptdev *eptdev;
+	struct rpmsg_endpoint *ept;
+
+	memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME));
+	chinfo.src = rpdev->src;
+	chinfo.dst = rpdev->dst;
+
+	eptdev =  __rpmsg_chrdev_eptdev_create(rpdev, &rpdev->dev, chinfo);
+	if (IS_ERR(eptdev))
+		return PTR_ERR(eptdev);
+
+	/*
+	 * Create the default endpoint associated to the rpmsg device and provide rpmsg_eptdev
+	 * structure as callback private data.
+	 */
+	ept = rpmsg_create_default_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev->chinfo);
+	if (!ept) {
+		dev_err(&rpdev->dev, "failed to create %s\n", eptdev->chinfo.name);
+		put_device(&eptdev->dev);
+		return -EINVAL;
+	}
+
+	/*
+	 * Do not allow the creation and release of an endpoint on /dev/rpmsgX open and close,
+	 * reuse the default endpoint instead
+	 */
+	eptdev->static_ept = true;
+
+	return 0;
+}
+
+static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
+{
+	int ret;
+
+	ret = device_for_each_child(&rpdev->dev, NULL, rpmsg_chrdev_eptdev_destroy);
+	if (ret)
+		dev_warn(&rpdev->dev, "failed to destroy endpoints: %d\n", ret);
+}
+
+static struct rpmsg_device_id rpmsg_chrdev_id_table[] = {
+	{ .name	= RPMSG_CHAR_DEVNAME },
+	{ },
+};
+
+static struct rpmsg_driver rpmsg_chrdev_driver = {
+	.probe = rpmsg_chrdev_probe,
+	.remove = rpmsg_chrdev_remove,
+	.id_table = rpmsg_chrdev_id_table,
+	.drv.name = "rpmsg_chrdev",
+};
+
 static int rpmsg_chrdev_init(void)
 {
 	int ret;
@@ -434,16 +491,30 @@ static int rpmsg_chrdev_init(void)
 	rpmsg_class = class_create(THIS_MODULE, "rpmsg");
 	if (IS_ERR(rpmsg_class)) {
 		pr_err("failed to create rpmsg class\n");
-		unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
-		return PTR_ERR(rpmsg_class);
+		ret = PTR_ERR(rpmsg_class);
+		goto free_region;
+	}
+
+	ret = register_rpmsg_driver(&rpmsg_chrdev_driver);
+	if (ret < 0) {
+		pr_err("rpmsg: failed to register rpmsg raw driver\n");
+		goto free_class;
 	}
 
 	return 0;
+
+free_class:
+	class_destroy(rpmsg_class);
+free_region:
+	unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
+
+	return ret;
 }
 postcore_initcall(rpmsg_chrdev_init);
 
 static void rpmsg_chrdev_exit(void)
 {
+	unregister_rpmsg_driver(&rpmsg_chrdev_driver);
 	class_destroy(rpmsg_class);
 	unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
 }
-- 
2.17.1