watchdog: renesas-wdt: Add support for WDIOF_CARDRESET

This patch adds the WDIOF_CARDRESET support for the Renesas platform
watchdog, to know if the board reboot is due to a watchdog reset.

This is done via the WOVF bit (bit 4) of the RWTCSRA register, which
indicates if RWTCNT overflowed, triggering the reset in last boot.

Signed-off-by: Veeraiyan Chidambaram <veeraiyan.chidambaram@in.bosch.com>
[takeshi.kihara.df: changed to read the RWTCSRA register while clock is
 enabled]
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Vladimir Zapolskiy <vz@mleia.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/renesas_wdt.c

@@ -121,7 +121,8 @@ static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
 }
 
 static const struct watchdog_info rwdt_ident = {
-	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
+		WDIOF_CARDRESET,
 	.identity = "Renesas WDT Watchdog",
 };
 
@@ -197,9 +198,10 @@ static int rwdt_probe(struct platform_device *pdev)
 		return PTR_ERR(clk);
 
 	pm_runtime_enable(&pdev->dev);
-
 	pm_runtime_get_sync(&pdev->dev);
 	priv->clk_rate = clk_get_rate(clk);
+	priv->wdev.bootstatus = (readb_relaxed(priv->base + RWTCSRA) &
+				RWTCSRA_WOVF) ? WDIOF_CARDRESET : 0;
 	pm_runtime_put(&pdev->dev);
 
 	if (!priv->clk_rate) {