ALSA: firewire-digi00x: add hwdep interface

This commit adds hwdep interface so as the other sound drivers for units
on IEEE 1394 bus have.

This interface is designed for mixer/control applications. By using this
interface, an application can get information about firewire node, can
lock/unlock kernel streaming and can get notification at starting/stopping
kernel streaming.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/digi00x/digi00x.c

@@ -72,6 +72,8 @@ static int snd_dg00x_probe(struct fw_unit *unit,
 	dg00x->unit = fw_unit_get(unit);
 
 	mutex_init(&dg00x->mutex);
+	spin_lock_init(&dg00x->lock);
+	init_waitqueue_head(&dg00x->hwdep_wait);
 
 	err = name_card(dg00x);
 	if (err < 0)
@@ -87,6 +89,10 @@ static int snd_dg00x_probe(struct fw_unit *unit,
 	if (err < 0)
 		goto error;
 
+	err = snd_dg00x_create_hwdep_device(dg00x);
+	if (err < 0)
+		goto error;
+
 	err = snd_card_register(card);
 	if (err < 0)
 		goto error;