diff --git a/sound/firewire/digi00x/Makefile b/sound/firewire/digi00x/Makefile
index deb3683..e42b5cc 100644
--- a/sound/firewire/digi00x/Makefile
+++ b/sound/firewire/digi00x/Makefile
@@ -1,3 +1,3 @@
 snd-digi00x-objs := digi00x.o digi00x-stream.o digi00x-proc.o digi00x-pcm.o \
-		    digi00x-midi.o digi00x-hwdep.o
+		    digi00x-midi.o digi00x-hwdep.o digi00x-protocol.o
 obj-m += snd-digi00x.o
diff --git a/sound/firewire/digi00x/digi00x-protocol.c b/sound/firewire/digi00x/digi00x-protocol.c
new file mode 100644
index 0000000..b19708d
--- /dev/null
+++ b/sound/firewire/digi00x/digi00x-protocol.c
@@ -0,0 +1,122 @@
+/*
+ * digi00x-protocol.c - a part of driver for Digidesign Digi 002/003 family
+ *
+ * Copyright (c) 2014-2015 Takashi Sakamoto
+ *
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#include "digi00x.h"
+
+static struct snd_dg00x *instances[SNDRV_CARDS];
+static DEFINE_SPINLOCK(instances_lock);
+
+static void handle_unknown_message(struct snd_dg00x *dg00x,
+				   unsigned long long offset, u32 *buf)
+{
+	snd_printk(KERN_INFO"%08llx: %08x\n", offset, be32_to_cpu(*buf));
+}
+
+static void handle_message(struct fw_card *card, struct fw_request *request,
+			   int tcode, int destination, int source,
+			   int generation, unsigned long long offset,
+			   void *data, size_t length, void *callback_data)
+{
+	u32 *buf = (__be32 *)data;
+	struct fw_device *device;
+	struct snd_dg00x *dg00x;
+	unsigned int i;
+
+	spin_lock_irq(&instances_lock);
+	for (i = 0; i < SNDRV_CARDS; i++) {
+		dg00x = instances[i];
+		if (dg00x == NULL)
+			continue;
+		device = fw_parent_device(dg00x->unit);
+		if (device->card != card)
+			continue;
+		smp_rmb();	/* node id vs. generation */
+		if (device->node_id != source)
+			continue;
+		break;
+	}
+
+	if (offset == 0xffffe0000000)
+		handle_unknown_message(dg00x, offset, buf);
+
+	spin_unlock_irq(&instances_lock);
+	fw_send_response(card, request, RCODE_COMPLETE);
+}
+
+/*
+ * Use the same range of address for asynchronous messages from any devices, to
+ * save resources on host controller.
+ */
+static struct fw_address_handler async_handler;
+
+int snd_dg00x_protocol_add_instance(struct snd_dg00x *dg00x)
+{
+	struct fw_device *device = fw_parent_device(dg00x->unit);
+	__be32 data[2];
+	unsigned int i;
+	int err;
+
+	/* Unknown. 4bytes. */
+	data[0] = cpu_to_be32((device->card->node_id << 16) |
+			      (async_handler.offset >> 32));
+	data[1] = cpu_to_be32(async_handler.offset);
+	err = snd_fw_transaction(dg00x->unit, TCODE_WRITE_BLOCK_REQUEST,
+				 0xffffe0000014ull, &data, sizeof(data), 0);
+	if (err < 0)
+		return err;
+
+	spin_lock_irq(&instances_lock);
+	for (i = 0; i < SNDRV_CARDS; i++) {
+		if (instances[i] != NULL)
+			continue;
+		instances[i] = dg00x;
+		break;
+	}
+	spin_unlock_irq(&instances_lock);
+
+	return 0;
+}
+
+void snd_dg00x_protocol_remove_instance(struct snd_dg00x *dg00x)
+{
+	unsigned int i;
+
+	spin_lock_irq(&instances_lock);
+	for (i = 0; i < SNDRV_CARDS; i++) {
+		if (instances[i] != dg00x)
+			continue;
+		instances[i] = NULL;
+		break;
+	}
+	spin_unlock_irq(&instances_lock);
+}
+
+int snd_dg00x_protocol_register(void)
+{
+	static const struct fw_address_region resp_register_region = {
+		.start	= 0xffffe0000000ull,
+		.end	= 0xffffe000ffffull,
+	};
+	int err;
+
+	async_handler.length = 4;
+	async_handler.address_callback = handle_message;
+	async_handler.callback_data = NULL;
+
+	err = fw_core_add_address_handler(&async_handler,
+					  &resp_register_region);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+void snd_dg00x_protocol_unregister(void)
+{
+	fw_core_remove_address_handler(&async_handler);
+}
diff --git a/sound/firewire/digi00x/digi00x.c b/sound/firewire/digi00x/digi00x.c
index c170cbb..db0997d 100644
--- a/sound/firewire/digi00x/digi00x.c
+++ b/sound/firewire/digi00x/digi00x.c
@@ -48,6 +48,7 @@ static void dg00x_card_free(struct snd_card *card)
 	struct snd_dg00x *dg00x = card->private_data;
 
 	snd_dg00x_stream_destroy_duplex(dg00x);
+	snd_dg00x_protocol_remove_instance(dg00x);
 
 	fw_unit_put(dg00x->unit);
 
@@ -99,6 +100,10 @@ static int snd_dg00x_probe(struct fw_unit *unit,
 	if (err < 0)
 		goto error;
 
+	err = snd_dg00x_protocol_add_instance(dg00x);
+	if (err < 0)
+		goto error;
+
 	err = snd_card_register(card);
 	if (err < 0)
 		goto error;
@@ -155,11 +160,18 @@ static struct fw_driver dg00x_driver = {
 
 static int __init snd_dg00x_init(void)
 {
+	int err;
+
+	err = snd_dg00x_protocol_register();
+	if (err < 0)
+		return err;
+
 	return driver_register(&dg00x_driver.driver);
 }
 
 static void __exit snd_dg00x_exit(void)
 {
+	snd_dg00x_protocol_unregister();
 	driver_unregister(&dg00x_driver.driver);
 }
 
diff --git a/sound/firewire/digi00x/digi00x.h b/sound/firewire/digi00x/digi00x.h
index 7503d31..85cfb39 100644
--- a/sound/firewire/digi00x/digi00x.h
+++ b/sound/firewire/digi00x/digi00x.h
@@ -78,6 +78,11 @@ enum snd_dg00x_optical_mode {
 	SND_DG00X_OPTICAL_MODE_SPDIF,
 };
 
+int snd_dg00x_protocol_add_instance(struct snd_dg00x *dg00x);
+void snd_dg00x_protocol_remove_instance(struct snd_dg00x *dg00x);
+int snd_dg00x_protocol_register(void);
+void snd_dg00x_protocol_unregister(void);
+
 extern const unsigned int snd_dg00x_stream_rates[SND_DG00X_RATE_COUNT];
 extern const unsigned int
 snd_dg00x_stream_mbla_data_channels[SND_DG00X_RATE_COUNT];
