[PATCH 04/11] fireface: add transaction support

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RME Fireface series doesn't transfer MIDI messages on isochronous packets.
The messages are transferred in asynchronous transactions.

The unit handles MIDI messages in asynchronous transactions transmitted in
two addresses; 0x000008018000 and 0x000008019000. These two are
corresponding to physical MIDI port 1 and 2.

The unit transfers MIDI messages by asynchronous transactions to certain
addresses. Drivers can decide upper 4 byte of the addresses by a write
transaction to 0x0000801003f4. Drivers have four options to the rest;
0x000000000, 0x00000080, 0x00000100, 0x00000180. Drivers can enable them
by write transactions to 0x00008010051c. This register may consist of
bit flags. In this mechanism, drivers cannot use Private space of IEEE 1212
in which they allow to add some side effects to read/write transactions.

This commit adds transaction support for MIDI messaging. To receive
asynchronous transactions, the driver allocates a range of address in
Memory space. The driver selects 0x00000000 as lower 4 byte of the
address, thus the driver retries to allocate when gaining unusable range.

Writing non-zero value to enable the transaction has side effects. This
commit write 0x0400001f for decide divice's initial state.

Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
---
 sound/firewire/fireface/Makefile               |   2 +-
 sound/firewire/fireface/fireface-transaction.c | 301 +++++++++++++++++++++++++
 sound/firewire/fireface/fireface.c             |   8 +
 sound/firewire/fireface/fireface.h             |  30 +++
 4 files changed, 340 insertions(+), 1 deletion(-)
 create mode 100644 sound/firewire/fireface/fireface-transaction.c

diff --git a/sound/firewire/fireface/Makefile b/sound/firewire/fireface/Makefile
index f7113ab..aa52e41 100644
--- a/sound/firewire/fireface/Makefile
+++ b/sound/firewire/fireface/Makefile
@@ -1,2 +1,2 @@
-snd-fireface-objs := fireface.o
+snd-fireface-objs := fireface.o fireface-transaction.o
 obj-$(CONFIG_SND_FIREFACE) += snd-fireface.o
diff --git a/sound/firewire/fireface/fireface-transaction.c b/sound/firewire/fireface/fireface-transaction.c
new file mode 100644
index 0000000..8365cb4
--- /dev/null
+++ b/sound/firewire/fireface/fireface-transaction.c
@@ -0,0 +1,301 @@
+/*
+ * fireface-transaction.c - a part of driver for RME Fireface series
+ *
+ * Copyright (c) 2015-2016 Takashi Sakamoto
+ *
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#include "fireface.h"
+
+static void finish_transmit_midi_msg(struct snd_ff *ff, unsigned int port,
+				     int rcode)
+{
+	struct snd_rawmidi_substream *substream =
+				ACCESS_ONCE(ff->rx_midi_substreams[port]);
+
+	if (rcode_is_permanent_error(rcode)) {
+		ff->rx_midi_error[port] = true;
+		return;
+	}
+
+	if (rcode != RCODE_COMPLETE) {
+		/* Transfer the message again, immediately. */
+		ff->next_ktime[port] = ktime_set(0, 0);
+		schedule_work(&ff->rx_midi_work[port]);
+		return;
+	}
+
+	snd_rawmidi_transmit_ack(substream, ff->rx_bytes[port]);
+	ff->rx_bytes[port] = 0;
+
+	if (!snd_rawmidi_transmit_empty(substream))
+		schedule_work(&ff->rx_midi_work[port]);
+}
+
+static void finish_transmit_midi0_msg(struct fw_card *card, int rcode,
+				      void *data, size_t length,
+				      void *callback_data)
+{
+	struct snd_ff *ff =
+		container_of(callback_data, struct snd_ff, transactions[0]);
+	finish_transmit_midi_msg(ff, 0, rcode);
+}
+
+static void finish_transmit_midi1_msg(struct fw_card *card, int rcode,
+				      void *data, size_t length,
+				      void *callback_data)
+{
+	struct snd_ff *ff =
+		container_of(callback_data, struct snd_ff, transactions[1]);
+	finish_transmit_midi_msg(ff, 1, rcode);
+}
+
+static inline void fill_midi_buf(struct snd_ff *ff, unsigned int port,
+				 unsigned int index, u8 byte)
+{
+	ff->msg_buf[port][index] = cpu_to_le32(byte);
+}
+
+static void transmit_midi_msg(struct snd_ff *ff, unsigned int port)
+{
+	struct snd_rawmidi_substream *substream =
+			ACCESS_ONCE(ff->rx_midi_substreams[port]);
+	u8 *buf = (u8 *)ff->msg_buf[port];
+	int i, len;
+
+	struct fw_device *fw_dev = fw_parent_device(ff->unit);
+	unsigned long long addr;
+	int generation;
+	fw_transaction_callback_t callback;
+
+	if (substream == NULL || snd_rawmidi_transmit_empty(substream))
+		return;
+
+	if (ff->rx_bytes[port] > 0 || ff->rx_midi_error[port])
+		return;
+
+	/* Do it in next chance. */
+	if (ktime_after(ff->next_ktime[port], ktime_get())) {
+		schedule_work(&ff->rx_midi_work[port]);
+		return;
+	}
+
+	len = snd_rawmidi_transmit_peek(substream, buf,
+					SND_FF_MAXIMIM_MIDI_QUADS);
+	if (len <= 0)
+		return;
+
+	for (i = len - 1; i >= 0; i--)
+		fill_midi_buf(ff, port, i, buf[i]);
+
+	if (port == 0) {
+		addr = SND_FF_ADDR_MIDI_RX_PORT_0;
+		callback = finish_transmit_midi0_msg;
+	} else {
+		addr = SND_FF_ADDR_MIDI_RX_PORT_1;
+		callback = finish_transmit_midi1_msg;
+	}
+
+	/* Set interval to next transaction. */
+	ff->next_ktime[port] = ktime_add_ns(ktime_get(),
+					    len * 8 * NSEC_PER_SEC / 31250);
+	ff->rx_bytes[port] = len;
+
+	/*
+	 * In Linux FireWire core, when generation is updated with memory
+	 * barrier, node id has already been updated. In this module, After
+	 * this smp_rmb(), load/store instructions to memory are completed.
+	 * Thus, both of generation and node id are available with recent
+	 * values. This is a light-serialization solution to handle bus reset
+	 * events on IEEE 1394 bus.
+	 */
+	generation = fw_dev->generation;
+	smp_rmb();
+	fw_send_request(fw_dev->card, &ff->transactions[port],
+			TCODE_WRITE_BLOCK_REQUEST,
+			fw_dev->node_id, generation, fw_dev->max_speed,
+			addr, &ff->msg_buf[port], len * 4,
+			callback, &ff->transactions[port]);
+}
+
+static void transmit_midi0_msg(struct work_struct *work)
+{
+	struct snd_ff *ff = container_of(work, struct snd_ff, rx_midi_work[0]);
+
+	transmit_midi_msg(ff, 0);
+}
+
+static void transmit_midi1_msg(struct work_struct *work)
+{
+	struct snd_ff *ff = container_of(work, struct snd_ff, rx_midi_work[1]);
+
+	transmit_midi_msg(ff, 1);
+}
+
+static void handle_midi_msg(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_ff *ff = callback_data;
+	__le32 *buf = data;
+	u32 quad;
+	u8 byte;
+	unsigned int index;
+	struct snd_rawmidi_substream *substream;
+	int i;
+
+	fw_send_response(card, request, RCODE_COMPLETE);
+
+	for (i = 0; i < length / 4; i++) {
+		quad = le32_to_cpu(buf[i]);
+
+		/* Message in first port. */
+		/*
+		 * This value may represent the index of this unit when the
+		 * same units are on the same IEEE 1394 bus. This driver don't
+		 * use it.
+		 */
+		index = (quad >> 8) & 0xff;
+		if (index > 0) {
+			substream = ACCESS_ONCE(ff->tx_midi_substreams[0]);
+			if (substream != NULL) {
+				byte = quad & 0xff;
+				snd_rawmidi_receive(substream, &byte, 1);
+			}
+		}
+
+		/* Message in second port. */
+		index = (quad >> 24) & 0xff;
+		if (index > 0) {
+			substream = ACCESS_ONCE(ff->tx_midi_substreams[1]);
+			if (substream != NULL) {
+				byte = (quad >> 16) & 0xff;
+				snd_rawmidi_receive(substream, &byte, 1);
+			}
+		}
+	}
+}
+
+static int allocate_own_address(struct snd_ff *ff, int i)
+{
+	struct fw_address_region midi_msg_region;
+	int err;
+
+	ff->async_handler.length = SND_FF_MAXIMIM_MIDI_QUADS * 4;
+	ff->async_handler.address_callback = handle_midi_msg;
+	ff->async_handler.callback_data = ff;
+
+	midi_msg_region.start = 0x000100000000 * i;
+	midi_msg_region.end = midi_msg_region.start + ff->async_handler.length;
+
+	err = fw_core_add_address_handler(&ff->async_handler, &midi_msg_region);
+	if (err >= 0) {
+		/* Controllers register this region of address. */
+		if (ff->async_handler.offset & 0x0000ffffffff) {
+			fw_core_remove_address_handler(&ff->async_handler);
+			err = -EAGAIN;
+		}
+	}
+
+	return err;
+}
+
+int snd_ff_transaction_reregister(struct snd_ff *ff)
+{
+	struct fw_card *fw_card = fw_parent_device(ff->unit)->card;
+	u32 addr;
+	__le32 reg;
+	int err;
+
+	/*
+	 * Controllers are allowed to register its node ID and upper 2 byte of
+	 * local address to listen asynchronous transactions. Rest of the local
+	 * address is decided later. This is the reason we should pay attension
+	 * to allocating the address.
+	 */
+	addr = (fw_card->node_id << 16) | (ff->async_handler.offset >> 32);
+	reg = cpu_to_le32(addr);
+	err = snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+				 SND_FF_ADDR_CONTROLLER_ADDR_HI,
+				 &reg, sizeof(reg), 0);
+	if (err < 0)
+		return err;
+
+	/*
+	 * The 3rd-6th bits in MSB of this register are used to indicate fixed
+	 * offset of address to transfer asynchronous transaction.
+	 *  - 6th: 0x00000180
+	 *  - 5th: 0x00000100
+	 *  - 4th: 0x00000080
+	 *  - 3rd: 0x00000000
+	 *
+	 * Here, we use 3rd bit because controllers are not allowed to register
+	 * arbitrary address for this purpose.
+	 *
+	 * The 7th and 8th bits in MSB of this register are used to the other
+	 * purpose.
+	 *
+	 * The 1st and 2nd bits in LSB of this register are used to cancel
+	 * transferring asynchronous transactions. These two bits have the same
+	 * effect.
+	 *  - 1st/2nd: cancel transferring
+	 *
+	 * This transaction has a side effect to configure the other options.
+	 * The LSM of this value means:
+	 *  - 5th: control quadlet speed
+	 *  - 4th: control double speed
+	 *  - 3rd: control base frequency bit 1
+	 *  - 2nd: control base frequency bit 0
+	 *  - 1st: use internal clock source
+	 */
+	reg = cpu_to_le32(0x0400001f);
+	return snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+				  SND_FF_ADDR_GENERAL_PARAMS,
+				  &reg, sizeof(reg), 0);
+}
+
+int snd_ff_transaction_register(struct snd_ff *ff)
+{
+	int i, err;
+
+	/*
+	 * Allocate in Memory Space of IEC 13213, but 8 byte in LSB should be
+	 * zero due to device specification.
+	 */
+	for (i = 0; i < 0xffff; i++) {
+		err = allocate_own_address(ff, i);
+		if (err != -EBUSY && err != -EAGAIN)
+			break;
+	}
+	if (err < 0)
+		return err;
+
+	err = snd_ff_transaction_reregister(ff);
+	if (err < 0)
+		return err;
+
+	INIT_WORK(&ff->rx_midi_work[0], transmit_midi0_msg);
+	INIT_WORK(&ff->rx_midi_work[1], transmit_midi1_msg);
+
+	return 0;
+}
+
+void snd_ff_transaction_unregister(struct snd_ff *ff)
+{
+	__le32 reg;
+
+	/* Stop transferring and listening. */
+	reg = cpu_to_le32(0x03000000);
+	snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+			  SND_FF_ADDR_GENERAL_PARAMS,
+			  &reg, sizeof(reg), 0);
+
+	reg = cpu_to_le32(0x00000000);
+	snd_fw_transaction(ff->unit, TCODE_WRITE_QUADLET_REQUEST,
+			   SND_FF_ADDR_CONTROLLER_ADDR_HI,
+			   &reg, sizeof(reg), 0);
+
+	fw_core_remove_address_handler(&ff->async_handler);
+}
diff --git a/sound/firewire/fireface/fireface.c b/sound/firewire/fireface/fireface.c
index f96913b..b3ee869 100644
--- a/sound/firewire/fireface/fireface.c
+++ b/sound/firewire/fireface/fireface.c
@@ -40,6 +40,8 @@ static void ff_card_free(struct snd_card *card)
 	/* The workqueue for registration uses the memory block. */
 	cancel_work_sync(&ff->dwork.work);
 
+	snd_ff_transaction_unregister(ff);
+
 	fw_unit_put(ff->unit);
 
 	mutex_destroy(&ff->mutex);
@@ -55,6 +57,10 @@ static void do_probe(struct work_struct *work)
 	if (ff->card->shutdown || ff->probed)
 		goto end;
 
+	err = snd_ff_transaction_register(ff);
+	if (err < 0)
+		goto end;
+
 	err = snd_card_register(ff->card);
 	if (err < 0)
 		goto end;
@@ -118,6 +124,8 @@ static void snd_ff_update(struct fw_unit *unit)
 				(get_jiffies_64() - fw_card->reset_jiffies);
 		mod_delayed_work(ff->dwork.wq, &ff->dwork, delay);
 	}
+
+	snd_ff_transaction_reregister(ff);
 }
 
 static void snd_ff_remove(struct fw_unit *unit)
diff --git a/sound/firewire/fireface/fireface.h b/sound/firewire/fireface/fireface.h
index 91e924c..6d132f9 100644
--- a/sound/firewire/fireface/fireface.h
+++ b/sound/firewire/fireface/fireface.h
@@ -31,6 +31,10 @@
 #include "../amdtp-stream.h"
 #include "../iso-resources.h"
 
+#define SND_FF_MAXIMIM_MIDI_QUADS	9
+#define SND_FF_IN_MIDI_PORTS		2
+#define SND_FF_OUT_MIDI_PORTS		2
+
 struct snd_ff_spec {
 	const char *const name;
 };
@@ -44,5 +48,31 @@ struct snd_ff {
 	struct delayed_work dwork;
 
 	const struct snd_ff_spec *spec;
+
+	/* To handle MIDI tx. */
+	struct snd_rawmidi_substream *tx_midi_substreams[SND_FF_IN_MIDI_PORTS];
+	struct fw_address_handler async_handler;
+
+	/* TO handle MIDI rx. */
+	struct snd_rawmidi_substream *rx_midi_substreams[SND_FF_OUT_MIDI_PORTS];
+	u8 running_status[SND_FF_OUT_MIDI_PORTS];
+	__le32 msg_buf[SND_FF_OUT_MIDI_PORTS][SND_FF_MAXIMIM_MIDI_QUADS];
+	struct work_struct rx_midi_work[SND_FF_OUT_MIDI_PORTS];
+	struct fw_transaction transactions[SND_FF_OUT_MIDI_PORTS];
+	ktime_t next_ktime[SND_FF_OUT_MIDI_PORTS];
+	bool rx_midi_error[SND_FF_OUT_MIDI_PORTS];
+	unsigned int rx_bytes[SND_FF_OUT_MIDI_PORTS];
 };
+
+#define SND_FF_ADDR_CONTROLLER_ADDR_HI	0x0000801003f4
+#define SND_FF_ADDR_GENERAL_PARAMS	0x00008010051c
+#define SND_FF_ADDR_MIDI_RX_PORT_0	0x000080180000
+#define SND_FF_ADDR_MIDI_RX_PORT_1	0x000080190000
+
+#define SND_FF_ADDR_MIDI_TX		0x000100000000
+
+int snd_ff_transaction_register(struct snd_ff *ff);
+int snd_ff_transaction_reregister(struct snd_ff *ff);
+void snd_ff_transaction_unregister(struct snd_ff *ff);
+
 #endif
-- 
2.5.0

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