ALSA: firewire-digi00x: add support for asynchronous messaging

Digi 002/003 family uses asynchronous transaction for messaging.
The address to transmit this message is stored on a certain register.

This commit allocates a range of address on OHCI 1394 host controller
to handle the messaging. As long as I know, the purpose of this message
seems to notify lost of synchronization. While, the meaning of content
of the message is not clear.

Actual examples of this messaging:
 * When clock source is set as internal:
 - 0x00007051
 - 0x00007052
 - 0x00007054
 - 0x00007057
 - 0x00007058
 * When clock source is set as somewhat external:
 - 0x00009000
 - 0x00009010
 - 0x00009020
 - 0x00009021
 - 0x00009022

The lost often occurs when using internal clock source. In this case,
users hear sounds with quite short gap every several minutes. In fact,
the lost is recovered temporarily.

When using with external clock source, the lost seems not to occur. The
mechanism is not clear yet.

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

1 files changed, 81 insertions, 0 deletions

diff --git a/sound/firewire/digi00x/digi00x-transaction.c b/sound/firewire/digi00x/digi00x-transaction.c
new file mode 100644
index 000000000000..49372901a1e1
--- /dev/null
+++ b/sound/firewire/digi00x/digi00x-transaction.c
@@ -0,0 +1,81 @@
+/*
+ * digi00x-transaction.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 <sound/asound.h>
+#include "digi00x.h"
+
+static void handle_unknown_message(struct snd_dg00x *dg00x,
+				   unsigned long long offset, __be32 *buf)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dg00x->lock, flags);
+	dg00x->msg = be32_to_cpu(*buf);
+	spin_unlock_irqrestore(&dg00x->lock, flags);
+
+	wake_up(&dg00x->hwdep_wait);
+}
+
+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)
+{
+	struct snd_dg00x *dg00x = callback_data;
+	__be32 *buf = (__be32 *)data;
+
+	if (offset == dg00x->async_handler.offset)
+		handle_unknown_message(dg00x, offset, buf);
+
+	fw_send_response(card, request, RCODE_COMPLETE);
+}
+
+int snd_dg00x_transaction_reregister(struct snd_dg00x *dg00x)
+{
+	struct fw_device *device = fw_parent_device(dg00x->unit);
+	__be32 data[2];
+
+	/* Unknown. 4bytes. */
+	data[0] = cpu_to_be32((device->card->node_id << 16) |
+			      (dg00x->async_handler.offset >> 32));
+	data[1] = cpu_to_be32(dg00x->async_handler.offset);
+	return snd_fw_transaction(dg00x->unit, TCODE_WRITE_BLOCK_REQUEST,
+				   DG00X_ADDR_BASE + DG00X_OFFSET_MESSAGE_ADDR,
+				   &data, sizeof(data), 0);
+}
+
+int snd_dg00x_transaction_register(struct snd_dg00x *dg00x)
+{
+	static const struct fw_address_region resp_register_region = {
+		.start	= 0xffffe0000000ull,
+		.end	= 0xffffe000ffffull,
+	};
+	int err;
+
+	dg00x->async_handler.length = 4;
+	dg00x->async_handler.address_callback = handle_message;
+	dg00x->async_handler.callback_data = dg00x;
+
+	err = fw_core_add_address_handler(&dg00x->async_handler,
+					  &resp_register_region);
+	if (err < 0)
+		return err;
+
+	err = snd_dg00x_transaction_reregister(dg00x);
+	if (err < 0) {
+		fw_core_remove_address_handler(&dg00x->async_handler);
+		dg00x->async_handler.address_callback = NULL;
+	}
+
+	return err;
+}
+
+void snd_dg00x_transaction_unregister(struct snd_dg00x *dg00x)
+{
+	fw_core_remove_address_handler(&dg00x->async_handler);
+}