linux-kernel - [PATCH 4.14 019/138] watchdog: dw_wdt: add stop watchdog operation

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Message-Id: <20180410212904.317032823@linuxfoundation.org>
Date:   Wed, 11 Apr 2018 00:23:29 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Oleksij Rempel <o.rempel@...gutronix.de>,
        Wim Van Sebroeck <wim@...ana.be>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-watchdog@...r.kernel.org,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.14 019/138] watchdog: dw_wdt: add stop watchdog operation

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oleksij Rempel <o.rempel@...gutronix.de>


[ Upstream commit 1bfe8889380890efe4943d125124f5a7b48571b0 ]

The only way of stopping the watchdog is by resetting it.
Add the watchdog op for stopping the device and reset if
a reset line is provided.

At same time WDOG_HW_RUNNING should be remove from dw_wdt_start.
As commented by Guenter Roeck:
dw_wdt sets WDOG_HW_RUNNING in its open function. Result is
that the kref_get() in watchdog_open() won't be executed. But then
kref_put() in close will be called since the watchdog now does stop.
This causes the imbalance.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
Cc: Wim Van Sebroeck <wim@...ana.be>
Cc: Guenter Roeck <linux@...ck-us.net>
Cc: linux-watchdog@...r.kernel.org
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@...ana.be>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/watchdog/dw_wdt.c |   18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -127,14 +127,27 @@ static int dw_wdt_start(struct watchdog_
 
 	dw_wdt_set_timeout(wdd, wdd->timeout);
 
-	set_bit(WDOG_HW_RUNNING, &wdd->status);
-
 	writel(WDOG_CONTROL_REG_WDT_EN_MASK,
 	       dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 
 	return 0;
 }
 
+static int dw_wdt_stop(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	if (!dw_wdt->rst) {
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+		return 0;
+	}
+
+	reset_control_assert(dw_wdt->rst);
+	reset_control_deassert(dw_wdt->rst);
+
+	return 0;
+}
+
 static int dw_wdt_restart(struct watchdog_device *wdd,
 			  unsigned long action, void *data)
 {
@@ -173,6 +186,7 @@ static const struct watchdog_info dw_wdt
 static const struct watchdog_ops dw_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= dw_wdt_start,
+	.stop		= dw_wdt_stop,
 	.ping		= dw_wdt_ping,
 	.set_timeout	= dw_wdt_set_timeout,
 	.get_timeleft	= dw_wdt_get_timeleft,