watchdog: mediatek: Make sure system reset gets asserted in mtk_wdt_restart()

Clear the IRQ enable bit of WDT_MODE before asserting software reset
in order to make TOPRGU issue a system reset signal instead of an IRQ.

Fixes: a44a455 ("watchdog: Add driver for Mediatek watchdog")
Signed-off-by: Yassine Oudjana <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Wim Van Sebroeck <[email protected]>

Author: Tooniis

drivers/watchdog/mtk_wdt.c

@@ -225,9 +225,15 @@ static int mtk_wdt_restart(struct watchdog_device *wdt_dev,
 {
 	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
 	void __iomem *wdt_base;
+	u32 reg;
 
 	wdt_base = mtk_wdt->wdt_base;
 
+	/* Enable reset in order to issue a system reset instead of an IRQ */
+	reg = readl(wdt_base + WDT_MODE);
+	reg &= ~WDT_MODE_IRQ_EN;
+	writel(reg | WDT_MODE_KEY, wdt_base + WDT_MODE);
+
 	while (1) {
 		writel(WDT_SWRST_KEY, wdt_base + WDT_SWRST);
 		mdelay(5);