watchdog: davinci: add GET_TIMELEFT option support

Currently, the davinci watchdog can be read while counting,
so we can add ability to report the remaining time before
the system will reboot.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/davinci_wdt.c

@@ -116,6 +116,31 @@ static int davinci_wdt_ping(struct watchdog_device *wdd)
 	return 0;
 }
 
+static unsigned int davinci_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	u64 timer_counter;
+	unsigned long freq;
+	u32 val;
+	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
+
+	/* if timeout has occured then return 0 */
+	val = ioread32(davinci_wdt->base + WDTCR);
+	if (val & WDFLAG)
+		return 0;
+
+	freq = clk_get_rate(davinci_wdt->clk);
+
+	if (!freq)
+		return 0;
+
+	timer_counter = ioread32(davinci_wdt->base + TIM12);
+	timer_counter |= ((u64)ioread32(davinci_wdt->base + TIM34) << 32);
+
+	do_div(timer_counter, freq);
+
+	return wdd->timeout - timer_counter;
+}
+
 static const struct watchdog_info davinci_wdt_info = {
 	.options = WDIOF_KEEPALIVEPING,
 	.identity = "DaVinci Watchdog",
@@ -126,6 +151,7 @@ static const struct watchdog_ops davinci_wdt_ops = {
 	.start		= davinci_wdt_start,
 	.stop		= davinci_wdt_ping,
 	.ping		= davinci_wdt_ping,
+	.get_timeleft	= davinci_wdt_get_timeleft,
 };
 
 static int davinci_wdt_probe(struct platform_device *pdev)