From ca074b63caeaf675017a8e3d0734d4a04cf6ad61 Mon Sep 17 00:00:00 2001
From: Marco Felsch <m.felsch@pengutronix.de>
Date: Mon, 28 May 2018 08:45:44 +0200
Subject: [PATCH] watchdog: da9063: Fix setting/changing timeout
Patch-mainline: v4.18-rc1
Git-commit: e46bb55dbc94b06f5ee466e2f50723b56781e661
References: bsc#1100843

If the timeout value is set more than once the DA9063 watchdog triggers
a reset signal which reset the system.

To update the timeout value we have to disable the watchdog, clear the
watchdog counter value and write the new timeout value to the watchdog.
Clearing the counter value is a feature to be on the safe side because the
data sheet doesn't describe the behaviour of the watchdog counter value
after a watchdog disabling-enable-sequence.

The patch is based on Philipp Zabel's previous patch.

Fixes: 5e9c16e37608 ("watchdog: Add DA9063 PMIC watchdog driver.")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Acked-by: Yadan Fan <ydfan@suse.com>
---
 drivers/watchdog/da9063_wdt.c |   26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

--- a/drivers/watchdog/da9063_wdt.c
+++ b/drivers/watchdog/da9063_wdt.c
@@ -48,8 +48,31 @@ static unsigned int da9063_wdt_timeout_t
 	return DA9063_TWDSCALE_MAX;
 }
 
+static int da9063_wdt_disable_timer(struct da9063 *da9063)
+{
+	return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
+				  DA9063_TWDSCALE_MASK,
+				  DA9063_TWDSCALE_DISABLE);
+}
+
 static int _da9063_wdt_set_timeout(struct da9063 *da9063, unsigned int regval)
 {
+	int ret;
+
+	/*
+	 * The watchdog triggers a reboot if a timeout value is already
+	 * programmed because the timeout value combines two functions
+	 * in one: indicating the counter limit and starting the watchdog.
+	 * The watchdog must be disabled to be able to change the timeout
+	 * value if the watchdog is already running. Then we can set the
+	 * new timeout value which enables the watchdog again.
+	 */
+	ret = da9063_wdt_disable_timer(da9063);
+	if (ret)
+		return ret;
+
+	usleep_range(150, 300);
+
 	return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
 				  DA9063_TWDSCALE_MASK, regval);
 }
@@ -74,8 +97,7 @@ static int da9063_wdt_stop(struct watchd
 	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 	int ret;
 
-	ret = regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
-				 DA9063_TWDSCALE_MASK, DA9063_TWDSCALE_DISABLE);
+	ret = da9063_wdt_disable_timer(da9063);
 	if (ret)
 		dev_alert(da9063->dev, "Watchdog failed to stop (err = %d)\n",
 			  ret);