examples: linux: remove any loading or unloading of modules

As the requirements for RPMsg usage can change over time, remove the loading
and unloading of drivers in the Linux app. Instead put the onus on the user to
manage the driver.

Update documentation of demos in READMEs

Signed-off-by: Ben Levinsky <ben.levinsky@amd.com>

examples/linux/rpmsg-echo-test/README.md

@@ -35,9 +35,21 @@
   # check remote processor state
   cat /sys/class/remoteproc/remoteproc0/state
 
+  # load rpmsg_char driver
+  modprobe rpmsg_char
+
+  # load rpmsg_ctrl driver
+  modprobe rpmsg_ctrl
+
   # Run echo_test application on host processor
   echo_test
 
+  # unload rpmsg_ctrl driver
+  modprobe -r rpmsg_ctrl
+
+  #unload rpmsg_char driver
+  modprobe -r rpmsg_char
+
   # Stop remote processor
   echo stop > /sys/class/remoteproc/remoteproc0/state
   ```

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

@@ -265,21 +265,6 @@ int main(int argc, char *argv[])
 	char ept_dev_path[32];
 
 	printf("\r\n Echo test start \r\n");
-
-	/* Load rpmsg_char driver */
-	printf("\r\nHost>probe rpmsg_char\r\n");
-	ret = system("set -x; lsmod; modprobe rpmsg_char");
-	if (ret < 0) {
-		perror("Failed to load rpmsg_char driver.\n");
-		return -EINVAL;
-	}
-
-	/*
-	 * try probbing rpmsg_ctrl for new kernel, However it's not failure
-	 * if rpmsg_ctrl is not available in case of kernel < 6.0
-	 */
-	system("modprobe rpmsg_ctrl");
-
 	lookup_channel(rpmsg_dev, &eptinfo);
 
 	while ((opt = getopt(argc, argv, "d:n:s:e:")) != -1) {

examples/linux/rpmsg-mat-mul/README.md

@@ -39,9 +39,21 @@
   # check remote processor state
   cat /sys/class/remoteproc/remoteproc0/state
 
+  # load rpmsg_char driver
+  modprobe rpmsg_char
+
+  # load rpmsg_ctrl driver
+  modprobe rpmsg_ctrl
+
   # Run Matrix multiplication application on host processor
   mat_mul_demo
 
+  # unload rpmsg_ctrl driver
+  modprobe -r rpmsg_ctrl
+
+  #unload rpmsg_char driver
+  modprobe -r rpmsg_char
+
   # Stop remote processor
   echo stop > /sys/class/remoteproc/remoteproc0/state
   ```

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

@@ -311,16 +311,6 @@ int main(int argc, char *argv[])
 	char ept_dev_path[32];
 
 	printf("\r\n Matrix multiplication demo start \r\n");
-
-	/* Load rpmsg_char driver */
-	printf("\r\nHost>probe rpmsg_char\r\n");
-	ret = system("set -x; lsmod; modprobe rpmsg_char");
-	if (ret < 0) {
-		perror("Failed to load rpmsg_char driver.\n");
-		return -EINVAL;
-	}
-	system("modprobe rpmsg_ctrl");
-
 	lookup_channel(rpmsg_dev, &eptinfo);
 
 	while ((opt = getopt(argc, argv, "d:n:s:e:")) != -1) {

examples/linux/rpmsg-proxy-app/README.md

@@ -65,9 +65,21 @@
   # Load and start target Firmware onto remote processor.
   echo start > /sys/class/remoteproc/remoteproc0/state
 
+  # load rpmsg_char driver
+  modprobe rpmsg_char
+
+  # load rpmsg_ctrl driver
+  modprobe rpmsg_ctrl
+
   # Run proxy application.
   proxy_app
 
+  # unload rpmsg_ctrl driver
+  modprobe -r rpmsg_ctrl
+
+  #unload rpmsg_char driver
+  modprobe -r rpmsg_char
+
   # Stop target firmware
   echo stop > /sys/class/remoteproc/remoteproc0/state
   ```

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

@@ -204,12 +204,6 @@ int file_write(char *path, char *str)
 	return 0;
 }
 
-/* Stop remote CPU and Unload drivers */
-void stop_remote(void)
-{
-	system("modprobe -r rpmsg_char");
-}
-
 void exit_action_handler(int signum)
 {
 	proxy->active = 0;
@@ -397,9 +391,6 @@ void kill_action_handler(int signum)
 	free(proxy->rpc);
 	free(proxy->rpc_response);
 	free(proxy);
-
-	/* Stop remote cpu and unload drivers */
-	stop_remote();
 }
 
 int main(int argc, char *argv[])
@@ -431,17 +422,6 @@ int main(int argc, char *argv[])
 	sigaction(SIGKILL, &kill_action, NULL);
 	sigaction(SIGHUP, &kill_action, NULL);
 
-	/* Load rpmsg_char driver */
-	printf("\r\nHost>probe rpmsg_char\r\n");
-	ret = system("modprobe rpmsg_char");
-	if (ret < 0) {
-		perror("Failed to load rpmsg_char driver.\n");
-		ret = -EINVAL;
-		goto error0;
-	}
-
-	system("modprobe rpmsg_ctrl");
-
 	/* Wait for rpmsg dev to be probed */
 	sleep(1);
 	ret = lookup_channel(rpmsg_dev_name, &eptinfo);
@@ -559,7 +539,5 @@ int main(int argc, char *argv[])
 		close(rpmsg_char_fd);
 	free(proxy);
 
-	stop_remote();
-
 	return ret;
 }