watchdog: mtk_wdt: Add reset_by_toprgu support

In some cases, the MediaTek watchdog requires the TOPRGU to reset
timer after system resets.

Provide a reset_by_toprgu parameter for configuration.
Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230117014023.2993-3-allen-kh.cheng@mediatek.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/mtk_wdt.c

@@ -50,6 +50,7 @@
 #define WDT_MODE_IRQ_EN		(1 << 3)
 #define WDT_MODE_AUTO_START	(1 << 4)
 #define WDT_MODE_DUAL_EN	(1 << 6)
+#define WDT_MODE_CNT_SEL	(1 << 8)
 #define WDT_MODE_KEY		0x22000000
 
 #define WDT_SWRST		0x14
@@ -70,6 +71,7 @@ struct mtk_wdt_dev {
 	spinlock_t lock; /* protects WDT_SWSYSRST reg */
 	struct reset_controller_dev rcdev;
 	bool disable_wdt_extrst;
+	bool reset_by_toprgu;
 };
 
 struct mtk_wdt_data {
@@ -279,6 +281,8 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
 		reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
 	if (mtk_wdt->disable_wdt_extrst)
 		reg &= ~WDT_MODE_EXRST_EN;
+	if (mtk_wdt->reset_by_toprgu)
+		reg |= WDT_MODE_CNT_SEL;
 	reg |= (WDT_MODE_EN | WDT_MODE_KEY);
 	iowrite32(reg, wdt_base + WDT_MODE);
 
@@ -408,6 +412,9 @@ static int mtk_wdt_probe(struct platform_device *pdev)
 	mtk_wdt->disable_wdt_extrst =
 		of_property_read_bool(dev->of_node, "mediatek,disable-extrst");
 
+	mtk_wdt->reset_by_toprgu =
+		of_property_read_bool(dev->of_node, "mediatek,reset-by-toprgu");
+
 	return 0;
 }