watchdog: aspeed: Add support for aspeed,reset-mask DT property

This property allows the device-tree to specify how the Aspeed
watchdog timer's reset mask register(s) should be set, so that
peripherals can be individually exempted from (or opted in to) being
reset when the watchdog timer expires.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230922104231.1434-6-zev@bewilderbeest.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Author: zevweiss

drivers/watchdog/aspeed_wdt.c

@@ -79,6 +79,8 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
 #define   WDT_TIMEOUT_STATUS_BOOT_SECONDARY	BIT(1)
 #define WDT_CLEAR_TIMEOUT_STATUS	0x14
 #define   WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION	BIT(0)
+#define WDT_RESET_MASK1		0x1c
+#define WDT_RESET_MASK2		0x20
 
 /*
  * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
@@ -402,6 +404,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 
 	if ((of_device_is_compatible(np, "aspeed,ast2500-wdt")) ||
 		(of_device_is_compatible(np, "aspeed,ast2600-wdt"))) {
+		u32 reset_mask[2];
+		size_t nrstmask = of_device_is_compatible(np, "aspeed,ast2600-wdt") ? 2 : 1;
 		u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
 
 		reg &= wdt->cfg->ext_pulse_width_mask;
@@ -419,6 +423,13 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 			reg |= WDT_OPEN_DRAIN_MAGIC;
 
 		writel(reg, wdt->base + WDT_RESET_WIDTH);
+
+		ret = of_property_read_u32_array(np, "aspeed,reset-mask", reset_mask, nrstmask);
+		if (!ret) {
+			writel(reset_mask[0], wdt->base + WDT_RESET_MASK1);
+			if (nrstmask > 1)
+				writel(reset_mask[1], wdt->base + WDT_RESET_MASK2);
+		}
 	}
 
 	if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {