ALSA: hda - Use common reboot notifier

The very same notifier code is used in both hda_intel.c and
hda_tegra.c.  Move it to the generic code.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c
index a562d86..8d9398a 100644
--- a/sound/pci/hda/hda_controller.c
+++ b/sound/pci/hda/hda_controller.c
@@ -27,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
+#include <linux/reboot.h>
 #include <sound/core.h>
 #include <sound/initval.h>
 #include "hda_priv.h"
@@ -1946,5 +1947,30 @@
 }
 EXPORT_SYMBOL_GPL(azx_init_stream);
 
+/*
+ * reboot notifier for hang-up problem at power-down
+ */
+static int azx_halt(struct notifier_block *nb, unsigned long event, void *buf)
+{
+	struct azx *chip = container_of(nb, struct azx, reboot_notifier);
+	snd_hda_bus_reboot_notify(chip->bus);
+	azx_stop_chip(chip);
+	return NOTIFY_OK;
+}
+
+void azx_notifier_register(struct azx *chip)
+{
+	chip->reboot_notifier.notifier_call = azx_halt;
+	register_reboot_notifier(&chip->reboot_notifier);
+}
+EXPORT_SYMBOL_GPL(azx_notifier_register);
+
+void azx_notifier_unregister(struct azx *chip)
+{
+	if (chip->reboot_notifier.notifier_call)
+		unregister_reboot_notifier(&chip->reboot_notifier);
+}
+EXPORT_SYMBOL_GPL(azx_notifier_unregister);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Common HDA driver funcitons");