ALSA: firewire-tascam: pick up data of state from tx isochronous pakcets

Units of TASCAM FireWire series multiplex PCM frames and state of
control surface into the same tx isochronous packets. One isochronous
packet includes a part of the state in a quadlet data. An image of the
state consists of 64 quadlet data.

This commit demultiplexes the state from tx isochronous packets.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/uapi/sound/firewire.h

@@ -88,4 +88,6 @@ struct snd_firewire_get_info {
  * Returns -EBUSY if the driver is already streaming.
  */
 
+#define SNDRV_FIREWIRE_TASCAM_STATE_COUNT	64
+
 #endif /* _UAPI_SOUND_FIREWIRE_H_INCLUDED */

sound/firewire/tascam/amdtp-tascam.c

@@ -117,6 +117,21 @@ int amdtp_tscm_add_pcm_hw_constraints(struct amdtp_stream *s,
 	return amdtp_stream_add_pcm_hw_constraints(s, runtime);
 }
 
+static void read_status_messages(struct amdtp_stream *s,
+				 __be32 *buffer, unsigned int data_blocks)
+{
+	struct snd_tscm *tscm = container_of(s, struct snd_tscm, tx_stream);
+	int i;
+
+	for (i = 0; i < data_blocks; i++) {
+		unsigned int index;
+
+		index = be32_to_cpu(buffer[0]) % SNDRV_FIREWIRE_TASCAM_STATE_COUNT;
+		tscm->state[index] = buffer[s->data_block_quadlets - 1];
+		buffer += s->data_block_quadlets;
+	}
+}
+
 static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
 					   __be32 *buffer,
 					   unsigned int data_blocks,
@@ -128,7 +143,7 @@ static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
 	if (data_blocks > 0 && pcm)
 		read_pcm_s32(s, pcm, buffer, data_blocks);
 
-	/* A place holder for control messages. */
+	read_status_messages(s, buffer, data_blocks);
 
 	return data_blocks;
 }

sound/firewire/tascam/tascam.h

@@ -89,6 +89,9 @@ struct snd_tscm {
 
 	/* For MIDI message outgoing transactions. */
 	struct snd_fw_async_midi_port out_ports[TSCM_MIDI_OUT_PORT_MAX];
+
+	// A cache of status information in tx isoc packets.
+	__be32 state[SNDRV_FIREWIRE_TASCAM_STATE_COUNT];
 };
 
 #define TSCM_ADDR_BASE			0xffff00000000ull