linux-kernel - [PATCH v4 14/16] rpmsg: char: introduce a RPMsg driver for the RPMsg char device

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Date:   Wed, 17 Feb 2021 14:29:03 +0100
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>,
        Andy Gross <agross@...nel.org>
CC:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-msm@...r.kernel.org>, <arnaud.pouliquen@...s.st.com>
Subject: [PATCH v4 14/16] rpmsg: char: introduce a RPMsg driver for the RPMsg char device

A RPMsg char device allows to probe the endpoint device on a remote name
service announcement. With this patch the /dev/rpmsgX interface is created
either by a user application or by the remote firmware.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
---
 drivers/rpmsg/rpmsg_char.c | 63 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 66dcb8845d6c..d5aa874865f7 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -28,6 +28,8 @@
 
 #define RPMSG_DEV_MAX	(MINORMASK + 1)
 
+#define RPMSG_CHAR_DEVNAME "rpmsg-raw"
+
 static dev_t rpmsg_major;
 static struct class *rpmsg_class;
 
@@ -408,6 +410,51 @@ int rpmsg_chrdev_create_eptdev(struct rpmsg_device *rpdev, struct device *parent
 }
 EXPORT_SYMBOL(rpmsg_chrdev_create_eptdev);
 
+static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
+{
+	struct rpmsg_channel_info chinfo;
+	struct rpmsg_eptdev *eptdev;
+
+	memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME));
+	chinfo.src = rpdev->src;
+	chinfo.dst = rpdev->dst;
+
+	eptdev = __rpmsg_chrdev_create_eptdev(rpdev, &rpdev->dev, chinfo);
+	if (IS_ERR(eptdev) && rpdev->ept) {
+		rpmsg_destroy_ept(rpdev->ept);
+		return PTR_ERR(eptdev);
+	}
+
+	/* Set the private field of the default endpoint to retrieve context on callback. */
+	rpdev->ept->priv = eptdev;
+
+	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,
+	.callback = rpmsg_ept_cb,
+	.drv = {
+		.name = "rpmsg_chrdev",
+	},
+};
+
 static int rpmsg_chrdev_init(void)
 {
 	int ret;
@@ -422,9 +469,23 @@ static int rpmsg_chrdev_init(void)
 	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 raw: failed to register rpmsg 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);
-- 
2.17.1