ALSA: firewire-motu: 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>

1 files changed, 38 insertions, 0 deletions

diff --git a/sound/firewire/motu/motu-stream.c b/sound/firewire/motu/motu-stream.c
index 911d3487f775..bd458029099e 100644
--- a/sound/firewire/motu/motu-stream.c
+++ b/sound/firewire/motu/motu-stream.c
@@ -341,3 +341,41 @@ void snd_motu_stream_destroy_duplex(struct snd_motu *motu)
 	motu->playback_substreams = 0;
 	motu->capture_substreams = 0;
 }
+
+static void motu_lock_changed(struct snd_motu *motu)
+{
+	motu->dev_lock_changed = true;
+	wake_up(&motu->hwdep_wait);
+}
+
+int snd_motu_stream_lock_try(struct snd_motu *motu)
+{
+	int err;
+
+	spin_lock_irq(&motu->lock);
+
+	if (motu->dev_lock_count < 0) {
+		err = -EBUSY;
+		goto out;
+	}
+
+	if (motu->dev_lock_count++ == 0)
+		motu_lock_changed(motu);
+	err = 0;
+out:
+	spin_unlock_irq(&motu->lock);
+	return err;
+}
+
+void snd_motu_stream_lock_release(struct snd_motu *motu)
+{
+	spin_lock_irq(&motu->lock);
+
+	if (WARN_ON(motu->dev_lock_count <= 0))
+		goto out;
+
+	if (--motu->dev_lock_count == 0)
+		motu_lock_changed(motu);
+out:
+	spin_unlock_irq(&motu->lock);
+}