leds: heartbeat: stop on shutdown

A halted kernel should not show a heartbeat.

[[email protected]: checkpatch fixes]
Signed-off-by: Alexander Holler <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Richard Purdie <[email protected]>
Cc: Bryan Wu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: aholler

drivers/leds/ledtrig-heartbeat.c

@@ -18,6 +18,7 @@
 #include <linux/timer.h>
 #include <linux/sched.h>
 #include <linux/leds.h>
+#include <linux/reboot.h>
 #include "leds.h"
 
 struct heartbeat_trig_data {
@@ -103,13 +104,38 @@ static struct led_trigger heartbeat_led_trigger = {
 	.deactivate = heartbeat_trig_deactivate,
 };
 
+static int heartbeat_reboot_notifier(struct notifier_block *nb,
+				     unsigned long code, void *unused)
+{
+	led_trigger_unregister(&heartbeat_led_trigger);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block heartbeat_reboot_nb = {
+	.notifier_call = heartbeat_reboot_notifier,
+};
+
+static struct notifier_block heartbeat_panic_nb = {
+	.notifier_call = heartbeat_reboot_notifier,
+};
+
 static int __init heartbeat_trig_init(void)
 {
-	return led_trigger_register(&heartbeat_led_trigger);
+	int rc = led_trigger_register(&heartbeat_led_trigger);
+
+	if (!rc) {
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &heartbeat_panic_nb);
+		register_reboot_notifier(&heartbeat_reboot_nb);
+	}
+	return rc;
 }
 
 static void __exit heartbeat_trig_exit(void)
 {
+	unregister_reboot_notifier(&heartbeat_reboot_nb);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &heartbeat_panic_nb);
 	led_trigger_unregister(&heartbeat_led_trigger);
 }