examples: linux: check rpmsg dev bind status

Check rpmsg device driver override and if correct driver
is already bound, then execute rest of application. If driver
is not bound, then bind rpmsg char driver.

Signed-off-by: Tanmay Shah <[email protected]>

examples/linux/common/common.c

@@ -63,6 +63,35 @@ char *get_rpmsg_ept_dev_name(const char *rpmsg_char_name,
 	return NULL;
 }
 
+int is_rpmsg_chrdev_bind(const char *rpmsg_dev_name)
+{
+	char fpath[256];
+	char rpmsg_chdrv[32] = {0};
+	int fd;
+	int ret;
+
+	/* rpmsg dev overrides path */
+	sprintf(fpath, "%s/devices/%s/driver_override",
+		RPMSG_BUS_SYS, rpmsg_dev_name);
+	printf("open %s\n", fpath);
+	fd = open(fpath, O_WRONLY);
+	if (fd < 0) {
+		fprintf(stderr, "Failed to open %s, %s\n",
+			fpath, strerror(errno));
+		return -EINVAL;
+	}
+	ret = read(fd, rpmsg_chdrv, sizeof(rpmsg_chdrv));
+	if (ret < 0) {
+		fprintf(stderr, "Failed to write %s to %s, %s\n",
+			rpmsg_chdrv, fpath, strerror(errno));
+		close(fd);
+		return -EINVAL;
+	}
+	close (fd);
+
+	return (strcmp(rpmsg_chdrv, "rpmsg_chrdev") == 0);
+}
+
 int bind_rpmsg_chrdev(const char *rpmsg_dev_name)
 {
 	char fpath[256];

examples/linux/common/common.h

@@ -14,5 +14,6 @@ char *get_rpmsg_ept_dev_name(const char *rpmsg_char_name,
 int bind_rpmsg_chrdev(const char *rpmsg_dev_name);
 int get_rpmsg_chrdev_fd(const char *rpmsg_dev_name, char *rpmsg_ctrl_name);
 int lookup_channel(char *out, struct rpmsg_endpoint_info *pep);
+int is_rpmsg_chrdev_bind(const char *rpmsg_dev_name);
 
 #endif /* __COMMON__H__ */

examples/linux/rpmsg-echo-test/echo_test.c

@@ -120,9 +120,12 @@ int main(int argc, char *argv[])
 		fprintf(stderr, "access(%s): %s\n", fpath, strerror(errno));
 		return -EINVAL;
 	}
-	ret = bind_rpmsg_chrdev(rpmsg_dev);
-	if (ret < 0)
-		return ret;
+
+	if (!is_rpmsg_chrdev_bind(rpmsg_dev)) {
+		ret = bind_rpmsg_chrdev(rpmsg_dev);
+		if (ret < 0)
+			return ret;
+	}
 
 	/* kernel >= 6.0 has new path for rpmsg_ctrl device */
 	charfd = get_rpmsg_chrdev_fd(rpmsg_ctrl_dev_name, rpmsg_char_name);

examples/linux/rpmsg-mat-mul/mat_mul_demo.c

@@ -156,9 +156,12 @@ int main(int argc, char *argv[])
 		fprintf(stderr, "access(%s): %s\n", fpath, strerror(errno));
 		return -EINVAL;
 	}
-	ret = bind_rpmsg_chrdev(rpmsg_dev);
-	if (ret < 0)
-		return ret;
+
+	if (!is_rpmsg_chrdev_bind(rpmsg_dev)) {
+		ret = bind_rpmsg_chrdev(rpmsg_dev);
+		if (ret < 0)
+			return ret;
+	}
 
 	/* The Linux kernel >= 6.0 expects rpmsg_ctrl interface under virtio*.rpmsg_ctrl*.* dir */
 	charfd = get_rpmsg_chrdev_fd(rpmsg_ctrl_dev_name, rpmsg_char_name);

examples/linux/rpmsg-proxy-app/proxy_app.c

@@ -253,9 +253,11 @@ int main(int argc, char *argv[])
 	if (ret < 0)
 		goto error0;
 
-	ret = bind_rpmsg_chrdev(rpmsg_dev_name);
-	if (ret < 0)
-		goto error0;
+	if (!is_rpmsg_chrdev_bind(rpmsg_dev_name)) {
+		ret = bind_rpmsg_chrdev(rpmsg_dev_name);
+		if (ret < 0)
+			goto error0;
+	}
 
 	/* The Linux kernel version >= 6.0 uses rpmsg_ctrl from virtio*.rpmsg_ctrl* dir */
 	rpmsg_char_fd = get_rpmsg_chrdev_fd(rpmsg_ctrl_dev_name, rpmsg_char_name);