ACPI: watchdog: Set default timeout in probe

If the BIOS default timeout for the watchdog is too small userspace may
not have enough time to configure new timeout after opening the device
before the system is already reset. For this reason program default
timeout of 30 seconds in the driver probe and allow userspace to change
this from command line or through module parameter (wdat_wdt.timeout).

Reported-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/watchdog/wdat_wdt.c

@@ -54,6 +54,13 @@ module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
+#define WDAT_DEFAULT_TIMEOUT	30
+
+static int timeout = WDAT_DEFAULT_TIMEOUT;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
+		 __MODULE_STRING(WDAT_DEFAULT_TIMEOUT) ")");
+
 static int wdat_wdt_read(struct wdat_wdt *wdat,
 	 const struct wdat_instruction *instr, u32 *value)
 {
@@ -438,6 +445,22 @@ static int wdat_wdt_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, wdat);
 
+	/*
+	 * Set initial timeout so that userspace has time to configure the
+	 * watchdog properly after it has opened the device. In some cases
+	 * the BIOS default is too short and causes immediate reboot.
+	 */
+	if (timeout * 1000 < wdat->wdd.min_hw_heartbeat_ms ||
+	    timeout * 1000 > wdat->wdd.max_hw_heartbeat_ms) {
+		dev_warn(dev, "Invalid timeout %d given, using %d\n",
+			 timeout, WDAT_DEFAULT_TIMEOUT);
+		timeout = WDAT_DEFAULT_TIMEOUT;
+	}
+
+	ret = wdat_wdt_set_timeout(&wdat->wdd, timeout);
+	if (ret)
+		return ret;
+
 	watchdog_set_nowayout(&wdat->wdd, nowayout);
 	return devm_watchdog_register_device(dev, &wdat->wdd);
 }