greybus: svc watchdog: allow it to be enabled/disabled from userspace

Sometimes you want to disable the SVC watchdog without having to patch
your kernel, so provide a sysfs file to do this.  This can let us do
power measurements, and let the firmware developers not go crazy
worrying that the kernel is going to reset their chips with no notice.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 51 insertions, 9 deletions

diff --git a/drivers/staging/greybus/svc_watchdog.c b/drivers/staging/greybus/svc_watchdog.c
index edb73ef..9bd68f4 100644
--- a/drivers/staging/greybus/svc_watchdog.c
+++ b/drivers/staging/greybus/svc_watchdog.c
@@ -15,7 +15,7 @@
 struct gb_svc_watchdog {
 	struct delayed_work	work;
 	struct gb_svc		*svc;
-	bool			finished;
+	bool			enabled;
 };
 
 static struct delayed_work reset_work;
@@ -65,11 +65,16 @@ static void do_work(struct work_struct *work)
 
 		INIT_DELAYED_WORK(&reset_work, greybus_reset);
 		queue_delayed_work(system_wq, &reset_work, HZ/2);
-		return;
+
+		/*
+		 * Disable ourselves, we don't want to trip again unless
+		 * userspace wants us to.
+		 */
+		watchdog->enabled = false;
 	}
 
 	/* resubmit our work to happen again, if we are still "alive" */
-	if (!watchdog->finished)
+	if (watchdog->enabled)
 		queue_delayed_work(system_wq, &watchdog->work,
 				   SVC_WATCHDOG_PERIOD);
 }
@@ -85,14 +90,12 @@ int gb_svc_watchdog_create(struct gb_svc *svc)
 	if (!watchdog)
 		return -ENOMEM;
 
-	watchdog->finished = false;
+	watchdog->enabled = false;
 	watchdog->svc = svc;
 	INIT_DELAYED_WORK(&watchdog->work, do_work);
 	svc->watchdog = watchdog;
 
-	queue_delayed_work(system_wq, &watchdog->work,
-			   SVC_WATCHDOG_PERIOD);
-	return 0;
+	return gb_svc_watchdog_enable(svc);
 }
 
 void gb_svc_watchdog_destroy(struct gb_svc *svc)
@@ -102,8 +105,47 @@ void gb_svc_watchdog_destroy(struct gb_svc *svc)
 	if (!watchdog)
 		return;
 
-	watchdog->finished = true;
-	cancel_delayed_work_sync(&watchdog->work);
+	gb_svc_watchdog_disable(svc);
 	svc->watchdog = NULL;
 	kfree(watchdog);
 }
+
+bool gb_svc_watchdog_enabled(struct gb_svc *svc)
+{
+	if (!svc || !svc->watchdog)
+		return false;
+	return svc->watchdog->enabled;
+}
+
+int gb_svc_watchdog_enable(struct gb_svc *svc)
+{
+	struct gb_svc_watchdog *watchdog;
+
+	if (!svc->watchdog)
+		return -ENODEV;
+
+	watchdog = svc->watchdog;
+	if (watchdog->enabled)
+		return 0;
+
+	watchdog->enabled = true;
+	queue_delayed_work(system_wq, &watchdog->work,
+			   SVC_WATCHDOG_PERIOD);
+	return 0;
+}
+
+int gb_svc_watchdog_disable(struct gb_svc *svc)
+{
+	struct gb_svc_watchdog *watchdog;
+
+	if (!svc->watchdog)
+		return -ENODEV;
+
+	watchdog = svc->watchdog;
+	if (!watchdog->enabled)
+		return 0;
+
+	watchdog->enabled = false;
+	cancel_delayed_work_sync(&watchdog->work);
+	return 0;
+}