[PATCH v4 1/2] watchdog: dw_wdt: add stop watchdog operation

From: Oleksij Rempel
Date: Tue Sep 26 2017 - 02:12:22 EST


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@xxxxxxxxxxxxxx>
Cc: Wim Van Sebroeck <wim@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: linux-watchdog@xxxxxxxxxxxxxxx
---

changes v4:
- remove WDOG_HW_RUNNING from dw_wdt_start.

changes v3:
- don't return error if rst is not present and set WDOG_HW_RUNNING bit
to notify watchdog core.

changes v2:
- test if dw_wdt->rst is NULL instead of IS_ERR

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,
--
2.11.0