Re: [PATCH 3/3] watchdog: dw_wdt: add stop watchdog operation

From: Guenter Roeck
Date: Thu Sep 22 2016 - 09:20:28 EST


On 09/22/2016 12:02 AM, Steffen Trumtrar wrote:
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.

Signed-off-by: Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
Cc: Wim Van Sebroeck <wim@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: linux-watchdog@xxxxxxxxxxxxxxx
---
drivers/watchdog/dw_wdt.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index e024722e8b3b..5b067984d5e8 100644
--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -137,6 +137,21 @@ static int dw_wdt_start(struct watchdog_device *wdd)
return 0;
}

+static int dw_wdt_stop(struct watchdog_device *wdd)
+{
+ struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+ if (IS_ERR(dw_wdt->rst)) {
+ dev_warn(wdd->parent, "No reset line. Will not stop.\n");

As mentioned in the other patch, this warning is not warranted.

Also, you'll need to inform the watchdog core that the watchdog is still
running, otherwise the system _will_ reset. That would be a definite
and unwanted change in behavior.

+ return PTR_ERR(dw_wdt->rst);

This is not an error. The code handled that situation before without
reporting an error, it can handle it now.

+ }
+
+ reset_control_assert(dw_wdt->rst);
+ reset_control_deassert(dw_wdt->rst);
+
+ return 0;
+}
+
static int dw_wdt_restart_handle(struct notifier_block *this,
unsigned long mode, void *cmd)
{
@@ -177,6 +192,7 @@ 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,