examples: linux: unbind rpmsg device

RPMsg linux app should unbind rpmsg device from char driver once
communication is done. Without unbind, rpmsg app can't bind same
device with rpmsg char driver again.

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

examples/linux/common/common.c

@@ -109,6 +109,33 @@ int bind_rpmsg_chrdev(const char *rpmsg_dev_name)
 	return 0;
 }
 
+int unbind_rpmsg_chrdev(const char *rpmsg_dev_name)
+{
+	char fpath[256];
+	char *rpmsg_chdrv = "rpmsg_chrdev";
+	int fd;
+	int ret;
+
+	/* unbind the rpmsg device to rpmsg char driver */
+	sprintf(fpath, "%s/drivers/%s/unbind", RPMSG_BUS_SYS, rpmsg_chdrv);
+	fd = open(fpath, O_WRONLY);
+	if (fd < 0) {
+		fprintf(stderr, "Failed to open %s, %s\n",
+			fpath, strerror(errno));
+		return -EINVAL;
+	}
+	printf("write %s to %s\n", rpmsg_dev_name, fpath);
+	ret = write(fd, rpmsg_dev_name, strlen(rpmsg_dev_name) + 1);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to write %s to %s, %s\n",
+			rpmsg_dev_name, fpath, strerror(errno));
+		close(fd);
+		return -EINVAL;
+	}
+	close(fd);
+	return 0;
+}
+
 int get_rpmsg_chrdev_fd(const char *rpmsg_dev_name, char *rpmsg_ctrl_name)
 {
 	char dpath[2*NAME_MAX];

examples/linux/common/common.h

@@ -12,6 +12,7 @@ char *get_rpmsg_ept_dev_name(const char *rpmsg_char_name,
                              const char *ept_name,
                              char *ept_dev_name);
 int bind_rpmsg_chrdev(const char *rpmsg_dev_name);
+int unbind_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);
 

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

@@ -225,6 +225,10 @@ int main(int argc, char *argv[])
 		printf("****\r\n");
 	}
 
+	ret = unbind_rpmsg_chrdev(rpmsg_dev);
+	if (ret < 0)
+		return ret;
+
 	send_shutdown(fd);
 	free(i_payload);
 	free(r_payload);

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

@@ -196,6 +196,10 @@ int main(int argc, char *argv[])
 		printf("End of Matrix multiplication demo round %d\n", i);
 	}
 
+	ret = unbind_rpmsg_chrdev(rpmsg_dev);
+	if (ret < 0)
+		return ret;
+
 	send_shutdown(fd);
 	close(fd);
 	if (charfd >= 0)

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

@@ -346,6 +346,10 @@ int main(int argc, char *argv[])
 	/* Close proxy rpmsg device */
 	close(proxy->rpmsg_proxy_fd);
 
+	ret = unbind_rpmsg_chrdev(rpmsg_dev_name);
+	if (ret < 0)
+		return ret;
+
 	/* Wait for other end to cleanup
 	 * Otherwise, virtio_rpmsg_bus can post msg with no recipient
 	 * warning as it can receive NS destroy after the rpmsg char