ALSA: firewire-motu: add MIDI functionality

In MOTU FireWire series, MIDI messages are multiplexed to isochronous
packets as well as PCM frames, while the way is different from the one
in IEC 61883-6.

MIDI messages are put into a certain position in message chunks. One data
block can includes one byte of the MIDI messages. When data block includes
a MIDI byte, the block has a flag in a certain position of the message
chunk. These positions are unique depending on protocols.

Once a data block includes a MIDI byte, some following data blocks includes
no MIDI bytes. Next MIDI byte appears on a data block corresponding to
next cycle of physical MIDI bus. This seems to avoid buffer overflow caused
by bandwidth differences between IEEE 1394 bus and physical MIDI bus.

This commit adds MIDI functionality to transfer/receive MIDI messages.

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

1 files changed, 153 insertions, 0 deletions

diff --git a/sound/firewire/motu/motu-midi.c b/sound/firewire/motu/motu-midi.c
new file mode 100644
index 000000000000..f232f29589d0
--- /dev/null
+++ b/sound/firewire/motu/motu-midi.c
@@ -0,0 +1,153 @@
+/*
+ * motu-midi.h - a part of driver for MOTU FireWire series
+ *
+ * Copyright (c) 2015-2017 Takashi Sakamoto <o-takashi@sakamocchi.jp>
+ *
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+#include "motu.h"
+
+static int midi_capture_open(struct snd_rawmidi_substream *substream)
+{
+	struct snd_motu *motu = substream->rmidi->private_data;
+	int err;
+
+	mutex_lock(&motu->mutex);
+
+	motu->capture_substreams++;
+	err = snd_motu_stream_start_duplex(motu, 0);
+
+	mutex_unlock(&motu->mutex);
+
+	return err;
+}
+
+static int midi_playback_open(struct snd_rawmidi_substream *substream)
+{
+	struct snd_motu *motu = substream->rmidi->private_data;
+	int err;
+
+	mutex_lock(&motu->mutex);
+
+	motu->playback_substreams++;
+	err = snd_motu_stream_start_duplex(motu, 0);
+
+	mutex_unlock(&motu->mutex);
+
+	return err;
+}
+
+static int midi_capture_close(struct snd_rawmidi_substream *substream)
+{
+	struct snd_motu *motu = substream->rmidi->private_data;
+
+	mutex_lock(&motu->mutex);
+
+	motu->capture_substreams--;
+	snd_motu_stream_stop_duplex(motu);
+
+	mutex_unlock(&motu->mutex);
+
+	return 0;
+}
+
+static int midi_playback_close(struct snd_rawmidi_substream *substream)
+{
+	struct snd_motu *motu = substream->rmidi->private_data;
+
+	mutex_lock(&motu->mutex);
+
+	motu->playback_substreams--;
+	snd_motu_stream_stop_duplex(motu);
+
+	mutex_unlock(&motu->mutex);
+
+	return 0;
+}
+
+static void midi_capture_trigger(struct snd_rawmidi_substream *substrm, int up)
+{
+	struct snd_motu *motu = substrm->rmidi->private_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&motu->lock, flags);
+
+	if (up)
+		amdtp_motu_midi_trigger(&motu->tx_stream, substrm->number,
+					substrm);
+	else
+		amdtp_motu_midi_trigger(&motu->tx_stream, substrm->number,
+					NULL);
+
+	spin_unlock_irqrestore(&motu->lock, flags);
+}
+
+static void midi_playback_trigger(struct snd_rawmidi_substream *substrm, int up)
+{
+	struct snd_motu *motu = substrm->rmidi->private_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&motu->lock, flags);
+
+	if (up)
+		amdtp_motu_midi_trigger(&motu->rx_stream, substrm->number,
+					substrm);
+	else
+		amdtp_motu_midi_trigger(&motu->rx_stream, substrm->number,
+					NULL);
+
+	spin_unlock_irqrestore(&motu->lock, flags);
+}
+
+static void set_midi_substream_names(struct snd_motu *motu,
+				     struct snd_rawmidi_str *str)
+{
+	struct snd_rawmidi_substream *subs;
+
+	list_for_each_entry(subs, &str->substreams, list) {
+		snprintf(subs->name, sizeof(subs->name),
+			 "%s MIDI %d", motu->card->shortname, subs->number + 1);
+	}
+}
+
+int snd_motu_create_midi_devices(struct snd_motu *motu)
+{
+	static struct snd_rawmidi_ops capture_ops = {
+		.open		= midi_capture_open,
+		.close		= midi_capture_close,
+		.trigger	= midi_capture_trigger,
+	};
+	static struct snd_rawmidi_ops playback_ops = {
+		.open		= midi_playback_open,
+		.close		= midi_playback_close,
+		.trigger	= midi_playback_trigger,
+	};
+	struct snd_rawmidi *rmidi;
+	struct snd_rawmidi_str *str;
+	int err;
+
+	/* create midi ports */
+	err = snd_rawmidi_new(motu->card, motu->card->driver, 0, 1, 1, &rmidi);
+	if (err < 0)
+		return err;
+
+	snprintf(rmidi->name, sizeof(rmidi->name),
+		 "%s MIDI", motu->card->shortname);
+	rmidi->private_data = motu;
+
+	rmidi->info_flags |= SNDRV_RAWMIDI_INFO_INPUT |
+			     SNDRV_RAWMIDI_INFO_OUTPUT |
+			     SNDRV_RAWMIDI_INFO_DUPLEX;
+
+	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT,
+			    &capture_ops);
+	str = &rmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT];
+	set_midi_substream_names(motu, str);
+
+	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
+			    &playback_ops);
+	str = &rmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT];
+	set_midi_substream_names(motu, str);
+
+	return 0;
+}