watchdog: pnx4008: add support for soft reset

Add support for explicit soft reset using the reboot mode.

The default reboot mode behavior is unchanged;
you can overwrite the default reboot type in the board specific file
"DT_MACHINE_START" definition using the "reboot_mode" parameter.
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

@@ -129,9 +129,16 @@ static int pnx4008_wdt_set_timeout(struct watchdog_device *wdd,
 static int pnx4008_restart_handler(struct watchdog_device *wdd,
 				   unsigned long mode, void *cmd)
 {
-	/* Instant assert of RESETOUT_N with pulse length 1mS */
-	writel(13000, WDTIM_PULSE(wdt_base));
-	writel(M_RES2 | RESFRC1 | RESFRC2, WDTIM_MCTRL(wdt_base));
+	if (mode == REBOOT_SOFT) {
+		/* Force match output active */
+		writel(EXT_MATCH0, WDTIM_EMR(wdt_base));
+		/* Internal reset on match output (RESOUT_N not asserted) */
+		writel(M_RES1, WDTIM_MCTRL(wdt_base));
+	} else {
+		/* Instant assert of RESETOUT_N with pulse length 1mS */
+		writel(13000, WDTIM_PULSE(wdt_base));
+		writel(M_RES2 | RESFRC1 | RESFRC2, WDTIM_MCTRL(wdt_base));
+	}
 
 	/* Wait for watchdog to reset system */
 	mdelay(1000);