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 <[e-mail]>
Reviewed-by: AngeloGioacchino Del Regno <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/mtk_wdt.c

···
 #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
···
 	spinlock_t lock; /* protects WDT_SWSYSRST reg */
 	struct reset_controller_dev rcdev;
 	bool disable_wdt_extrst;
+	bool reset_by_toprgu;
 };
 
 struct mtk_wdt_data {
···
 		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);
 
···
 
 	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;
 }