ALSA: fireface: add support for packet streaming on Fireface 800

This commit adds a functionality to multiplex PCM frames into isochronous
packets and demultiplex PCM frames from isochronous packets for ALSA PCM
applications.

Fireface 800 voluntarily maintains resources for tx isochronous
communication.  It performs reservation of isochronous channel and
allocation/update of bandwidth in some cases below:
 - at a first request to allocation after bus resets
 - at requests to allocation when further bandwidth is required

When request is grant and the unit is prepared, read data from
0x0000801c0008 represents isochronous channel for tx stream, then
the unit can handle requests to start communication. If driver
send the request without checking the register, the unit takes
panic to continue bus resets. The unit starts transmission of
tx packets after receiving several rx packets from driver.

I note that the unit can process tx/rx packets and generate/record
sound regardless of HOST LED.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/fireface/ff-protocol-ff800.c

@@ -6,8 +6,122 @@
  * Licensed under the terms of the GNU General Public License, version 2.
  */
 
+#include <linux/delay.h>
+
 #include "ff.h"
 
+#define FF800_STF		0x0000fc88f000
+#define FF800_RX_PACKET_FORMAT	0x0000fc88f004
+#define FF800_ALLOC_TX_STREAM	0x0000fc88f008
+#define FF800_ISOC_COMM_START	0x0000fc88f00c
+#define   FF800_TX_S800_FLAG	0x00000800
+#define FF800_ISOC_COMM_STOP	0x0000fc88f010
+
+#define FF800_TX_PACKET_ISOC_CH	0x0000801c0008
+
+static int allocate_rx_resources(struct snd_ff *ff)
+{
+	u32 data;
+	__le32 reg;
+	int err;
+
+	// Controllers should allocate isochronous resources for rx stream.
+	err = fw_iso_resources_allocate(&ff->rx_resources,
+				amdtp_stream_get_max_payload(&ff->rx_stream),
+				fw_parent_device(ff->unit)->max_speed);
+	if (err < 0)
+		return err;
+
+	// Set isochronous channel and the number of quadlets of rx packets.
+	data = ff->rx_stream.data_block_quadlets << 3;
+	data = (data << 8) | ff->rx_resources.channel;
+	reg = cpu_to_le32(data);
+	return snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+				FF800_RX_PACKET_FORMAT, &reg, sizeof(reg), 0);
+}
+
+static int allocate_tx_resources(struct snd_ff *ff)
+{
+	__le32 reg;
+	unsigned int count;
+	unsigned int tx_isoc_channel;
+	int err;
+
+	reg = cpu_to_le32(ff->tx_stream.data_block_quadlets);
+	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+				 FF800_ALLOC_TX_STREAM, &reg, sizeof(reg), 0);
+	if (err < 0)
+		return err;
+
+	// Wait till the format of tx packet is available.
+	count = 0;
+	while (count++ < 10) {
+		u32 data;
+		err = snd_fw_transaction(ff->unit, TCODE_READ_QUADLET_REQUEST,
+				FF800_TX_PACKET_ISOC_CH, &reg, sizeof(reg), 0);
+		if (err < 0)
+			return err;
+
+		data = le32_to_cpu(reg);
+		if (data != 0xffffffff) {
+			tx_isoc_channel = data;
+			break;
+		}
+
+		msleep(50);
+	}
+	if (count >= 10)
+		return -ETIMEDOUT;
+
+	// NOTE: this is a makeshift to start OHCI 1394 IR context in the
+	// channel. On the other hand, 'struct fw_iso_resources.allocated' is
+	// not true and it's not deallocated at stop.
+	ff->tx_resources.channel = tx_isoc_channel;
+
+	return 0;
+}
+
+static int ff800_begin_session(struct snd_ff *ff, unsigned int rate)
+{
+	__le32 reg;
+	int err;
+
+	reg = cpu_to_le32(rate);
+	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+				 FF800_STF, &reg, sizeof(reg), 0);
+	if (err < 0)
+		return err;
+
+	// If starting isochronous communication immediately, change of STF has
+	// no effect. In this case, the communication runs based on former STF.
+	// Let's sleep for a bit.
+	msleep(100);
+
+	err = allocate_rx_resources(ff);
+	if (err < 0)
+		return err;
+
+	err = allocate_tx_resources(ff);
+	if (err < 0)
+		return err;
+
+	reg = cpu_to_le32(0x80000000);
+	reg |= cpu_to_le32(ff->tx_stream.data_block_quadlets);
+	if (fw_parent_device(ff->unit)->max_speed == SCODE_800)
+		reg |= cpu_to_le32(FF800_TX_S800_FLAG);
+	return snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+				 FF800_ISOC_COMM_START, &reg, sizeof(reg), 0);
+}
+
+static void ff800_finish_session(struct snd_ff *ff)
+{
+	__le32 reg;
+
+	reg = cpu_to_le32(0x80000000);
+	snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+			   FF800_ISOC_COMM_STOP, &reg, sizeof(reg), 0);
+}
+
 static void ff800_handle_midi_msg(struct snd_ff *ff, __le32 *buf, size_t length)
 {
 	int i;
@@ -24,4 +138,6 @@ static void ff800_handle_midi_msg(struct snd_ff *ff, __le32 *buf, size_t length)
 
 const struct snd_ff_protocol snd_ff_protocol_ff800 = {
 	.handle_midi_msg	= ff800_handle_midi_msg,
+	.begin_session		= ff800_begin_session,
+	.finish_session		= ff800_finish_session,
 };

sound/firewire/fireface/ff.c

@@ -31,8 +31,7 @@ static void ff_card_free(struct snd_card *card)
 {
 	struct snd_ff *ff = card->private_data;
 
-	if (ff->spec->protocol->begin_session)
-		snd_ff_stream_destroy_duplex(ff);
+	snd_ff_stream_destroy_duplex(ff);
 	snd_ff_transaction_unregister(ff);
 }
 
@@ -57,11 +56,9 @@ static void do_registration(struct work_struct *work)
 
 	name_card(ff);
 
-	if (ff->spec->protocol->begin_session) {
-		err = snd_ff_stream_init_duplex(ff);
-		if (err < 0)
-			goto error;
-	}
+	err = snd_ff_stream_init_duplex(ff);
+	if (err < 0)
+		goto error;
 
 	snd_ff_proc_init(ff);
 
@@ -69,15 +66,13 @@ static void do_registration(struct work_struct *work)
 	if (err < 0)
 		goto error;
 
-	if (ff->spec->protocol->begin_session) {
-		err = snd_ff_create_pcm_devices(ff);
-		if (err < 0)
-			goto error;
+	err = snd_ff_create_pcm_devices(ff);
+	if (err < 0)
+		goto error;
 
-		err = snd_ff_create_hwdep_devices(ff);
-		if (err < 0)
-			goto error;
-	}
+	err = snd_ff_create_hwdep_devices(ff);
+	if (err < 0)
+		goto error;
 
 	err = snd_card_register(ff->card);
 	if (err < 0)
@@ -126,7 +121,7 @@ static void snd_ff_update(struct fw_unit *unit)
 
 	snd_ff_transaction_reregister(ff);
 
-	if (ff->registered && ff->spec->protocol->begin_session)
+	if (ff->registered)
 		snd_ff_stream_update_duplex(ff);
 }
 
@@ -152,6 +147,8 @@ static void snd_ff_remove(struct fw_unit *unit)
 
 static const struct snd_ff_spec spec_ff800 = {
 	.name = "Fireface800",
+	.pcm_capture_channels = {28, 20, 12},
+	.pcm_playback_channels = {28, 20, 12},
 	.midi_in_ports = 1,
 	.midi_out_ports = 1,
 	.protocol = &snd_ff_protocol_ff800,