watchdog: dw_wdt: add stop watchdog operation

Web:        https://git.kernel.org/torvalds/c/1bfe8889380890efe4943d125124f5a7b48571b0
Commit:     1bfe8889380890efe4943d125124f5a7b48571b0
Parent:     d4238aa458b8c3e64d6f124aafa5c230cae31d6a
Refname:    refs/heads/master
Author:     Oleksij Rempel <[email protected]>
AuthorDate: Tue Sep 26 08:11:22 2017 +0200
Committer:  Wim Van Sebroeck <[email protected]>
CommitDate: Thu Dec 28 20:44:55 2017 +0100

    watchdog: dw_wdt: add stop watchdog operation
    
    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 <[email protected]>
    Cc: Wim Van Sebroeck <[email protected]>
    Cc: Guenter Roeck <[email protected]>
    Cc: [email protected]
    Reviewed-by: Guenter Roeck <[email protected]>
    Signed-off-by: Guenter Roeck <[email protected]>
    Signed-off-by: Wim Van Sebroeck <[email protected]>
---
 drivers/watchdog/dw_wdt.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index 36be987ff9ef..c2f4ff516230 100644
--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -127,14 +127,27 @@ static int dw_wdt_start(struct watchdog_device *wdd)
 
 	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_ident = {
 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,
--
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