watchdog: pnx4008: restart: support "cmd" from userspace

Added support to verify if a "cmd" is passed from the userspace program rebooting the system;
- if a valid "cmd" is available, handle it;
- If the received "cmd" is not supported, use the default reboot mode.

Signed-off-by: Sylvain Lemieux <slemieux@tycoint.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/pnx4008_wdt.c

@@ -129,6 +129,21 @@ static int pnx4008_wdt_set_timeout(struct watchdog_device *wdd,
 static int pnx4008_restart_handler(struct watchdog_device *wdd,
 				   unsigned long mode, void *cmd)
 {
+	const char *boot_cmd = cmd;
+
+	/*
+	 * Verify if a "cmd" passed from the userspace program rebooting
+	 * the system; if available, handle it.
+	 * - For details, see the 'reboot' syscall in kernel/reboot.c
+	 * - If the received "cmd" is not supported, use the default mode.
+	 */
+	if (boot_cmd) {
+		if (boot_cmd[0] == 'h')
+			mode = REBOOT_HARD;
+		else if (boot_cmd[0] == 's')
+			mode = REBOOT_SOFT;
+	}
+
 	if (mode == REBOOT_SOFT) {
 		/* Force match output active */
 		writel(EXT_MATCH0, WDTIM_EMR(wdt_base));