drivers/watchdog: ASPEED reference dev tree properties for config

Reference the system device tree when configuring the watchdog
engines. If property 'aspeed,reset_type' is present then set
reset behavior based on the specified value.  This can be one of
three different mutually exclusive values
  * cpu - Reset CPU only on watchdog timeout
  * soc - Reset System on Chip
  * system - Full system reset

No reset can also be specified by indicating:
  * none - No reset, assumes another watchdog is responsible for
           this.

Add optional property 'aspeed,external-signal'. If present then
configure to generate external signal on watchdog timeout.

Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/aspeed_wdt.c

@@ -36,6 +36,7 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
 #define WDT_CTRL		0x0C
 #define   WDT_CTRL_RESET_MODE_SOC	(0x00 << 5)
 #define   WDT_CTRL_RESET_MODE_FULL_CHIP	(0x01 << 5)
+#define   WDT_CTRL_RESET_MODE_ARM_CPU	(0x10 << 5)
 #define   WDT_CTRL_1MHZ_CLK		BIT(4)
 #define   WDT_CTRL_WDT_EXT		BIT(3)
 #define   WDT_CTRL_WDT_INTR		BIT(2)
@@ -140,6 +141,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 {
 	struct aspeed_wdt *wdt;
 	struct resource *res;
+	struct device_node *np;
+	const char *reset_type;
 	int ret;
 
 	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
@@ -164,14 +167,30 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
 	wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
 	watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
 
+	wdt->ctrl = WDT_CTRL_1MHZ_CLK;
+
 	/*
 	 * Control reset on a per-device basis to ensure the
-	 * host is not affected by a BMC reboot, so only reset
-	 * the SOC and not the full chip
+	 * host is not affected by a BMC reboot
 	 */
-	wdt->ctrl = WDT_CTRL_RESET_MODE_SOC |
-		WDT_CTRL_1MHZ_CLK |
-		WDT_CTRL_RESET_SYSTEM;
+	np = pdev->dev.of_node;
+	ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
+	if (ret) {
+		wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM;
+	} else {
+		if (!strcmp(reset_type, "cpu"))
+			wdt->ctrl |= WDT_CTRL_RESET_MODE_ARM_CPU;
+		else if (!strcmp(reset_type, "soc"))
+			wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC;
+		else if (!strcmp(reset_type, "system"))
+			wdt->ctrl |= WDT_CTRL_RESET_SYSTEM;
+		else if (strcmp(reset_type, "none"))
+			return -EINVAL;
+	}
+	if (of_property_read_bool(np, "aspeed,external-signal"))
+		wdt->ctrl |= WDT_CTRL_WDT_EXT;
+
+	writel(wdt->ctrl, wdt->base + WDT_CTRL);
 
 	if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE)  {
 		aspeed_wdt_start(&wdt->wdd);