Linux-libre 4.4-gnupck-4.4-gnu

1 files changed, 863 insertions, 0 deletions

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
new file mode 100644
index 000000000..ed2902609
--- /dev/null
+++ b/sound/firewire/amdtp-stream.c
@@ -0,0 +1,863 @@
+/*
+ * Audio and Music Data Transmission Protocol (IEC 61883-6) streams
+ * with Common Isochronous Packet (IEC 61883-1) headers
+ *
+ * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/firewire.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include "amdtp-stream.h"
+
+#define TICKS_PER_CYCLE		3072
+#define CYCLES_PER_SECOND	8000
+#define TICKS_PER_SECOND	(TICKS_PER_CYCLE * CYCLES_PER_SECOND)
+
+#define TRANSFER_DELAY_TICKS	0x2e00 /* 479.17 microseconds */
+
+/* isochronous header parameters */
+#define ISO_DATA_LENGTH_SHIFT	16
+#define TAG_CIP			1
+
+/* common isochronous packet header parameters */
+#define CIP_EOH_SHIFT		31
+#define CIP_EOH			(1u << CIP_EOH_SHIFT)
+#define CIP_EOH_MASK		0x80000000
+#define CIP_SID_SHIFT		24
+#define CIP_SID_MASK		0x3f000000
+#define CIP_DBS_MASK		0x00ff0000
+#define CIP_DBS_SHIFT		16
+#define CIP_DBC_MASK		0x000000ff
+#define CIP_FMT_SHIFT		24
+#define CIP_FMT_MASK		0x3f000000
+#define CIP_FDF_MASK		0x00ff0000
+#define CIP_FDF_SHIFT		16
+#define CIP_SYT_MASK		0x0000ffff
+#define CIP_SYT_NO_INFO		0xffff
+
+/* Audio and Music transfer protocol specific parameters */
+#define CIP_FMT_AM		0x10
+#define AMDTP_FDF_NO_DATA	0xff
+
+/* TODO: make these configurable */
+#define INTERRUPT_INTERVAL	16
+#define QUEUE_LENGTH		48
+
+#define IN_PACKET_HEADER_SIZE	4
+#define OUT_PACKET_HEADER_SIZE	0
+
+static void pcm_period_tasklet(unsigned long data);
+
+/**
+ * amdtp_stream_init - initialize an AMDTP stream structure
+ * @s: the AMDTP stream to initialize
+ * @unit: the target of the stream
+ * @dir: the direction of stream
+ * @flags: the packet transmission method to use
+ * @fmt: the value of fmt field in CIP header
+ * @process_data_blocks: callback handler to process data blocks
+ * @protocol_size: the size to allocate newly for protocol
+ */
+int amdtp_stream_init(struct amdtp_stream *s, struct fw_unit *unit,
+		      enum amdtp_stream_direction dir, enum cip_flags flags,
+		      unsigned int fmt,
+		      amdtp_stream_process_data_blocks_t process_data_blocks,
+		      unsigned int protocol_size)
+{
+	if (process_data_blocks == NULL)
+		return -EINVAL;
+
+	s->protocol = kzalloc(protocol_size, GFP_KERNEL);
+	if (!s->protocol)
+		return -ENOMEM;
+
+	s->unit = unit;
+	s->direction = dir;
+	s->flags = flags;
+	s->context = ERR_PTR(-1);
+	mutex_init(&s->mutex);
+	tasklet_init(&s->period_tasklet, pcm_period_tasklet, (unsigned long)s);
+	s->packet_index = 0;
+
+	init_waitqueue_head(&s->callback_wait);
+	s->callbacked = false;
+	s->sync_slave = NULL;
+
+	s->fmt = fmt;
+	s->process_data_blocks = process_data_blocks;
+
+	return 0;
+}
+EXPORT_SYMBOL(amdtp_stream_init);
+
+/**
+ * amdtp_stream_destroy - free stream resources
+ * @s: the AMDTP stream to destroy
+ */
+void amdtp_stream_destroy(struct amdtp_stream *s)
+{
+	WARN_ON(amdtp_stream_running(s));
+	kfree(s->protocol);
+	mutex_destroy(&s->mutex);
+}
+EXPORT_SYMBOL(amdtp_stream_destroy);
+
+const unsigned int amdtp_syt_intervals[CIP_SFC_COUNT] = {
+	[CIP_SFC_32000]  =  8,
+	[CIP_SFC_44100]  =  8,
+	[CIP_SFC_48000]  =  8,
+	[CIP_SFC_88200]  = 16,
+	[CIP_SFC_96000]  = 16,
+	[CIP_SFC_176400] = 32,
+	[CIP_SFC_192000] = 32,
+};
+EXPORT_SYMBOL(amdtp_syt_intervals);
+
+const unsigned int amdtp_rate_table[CIP_SFC_COUNT] = {
+	[CIP_SFC_32000]  =  32000,
+	[CIP_SFC_44100]  =  44100,
+	[CIP_SFC_48000]  =  48000,
+	[CIP_SFC_88200]  =  88200,
+	[CIP_SFC_96000]  =  96000,
+	[CIP_SFC_176400] = 176400,
+	[CIP_SFC_192000] = 192000,
+};
+EXPORT_SYMBOL(amdtp_rate_table);
+
+/**
+ * amdtp_stream_add_pcm_hw_constraints - add hw constraints for PCM substream
+ * @s:		the AMDTP stream, which must be initialized.
+ * @runtime:	the PCM substream runtime
+ */
+int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s,
+					struct snd_pcm_runtime *runtime)
+{
+	int err;
+
+	/*
+	 * Currently firewire-lib processes 16 packets in one software
+	 * interrupt callback. This equals to 2msec but actually the
+	 * interval of the interrupts has a jitter.
+	 * Additionally, even if adding a constraint to fit period size to
+	 * 2msec, actual calculated frames per period doesn't equal to 2msec,
+	 * depending on sampling rate.
+	 * Anyway, the interval to call snd_pcm_period_elapsed() cannot 2msec.
+	 * Here let us use 5msec for safe period interrupt.
+	 */
+	err = snd_pcm_hw_constraint_minmax(runtime,
+					   SNDRV_PCM_HW_PARAM_PERIOD_TIME,
+					   5000, UINT_MAX);
+	if (err < 0)
+		goto end;
+
+	/* Non-Blocking stream has no more constraints */
+	if (!(s->flags & CIP_BLOCKING))
+		goto end;
+
+	/*
+	 * One AMDTP packet can include some frames. In blocking mode, the
+	 * number equals to SYT_INTERVAL. So the number is 8, 16 or 32,
+	 * depending on its sampling rate. For accurate period interrupt, it's
+	 * preferrable to align period/buffer sizes to current SYT_INTERVAL.
+	 *
+	 * TODO: These constraints can be improved with proper rules.
+	 * Currently apply LCM of SYT_INTERVALs.
+	 */
+	err = snd_pcm_hw_constraint_step(runtime, 0,
+					 SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 32);
+	if (err < 0)
+		goto end;
+	err = snd_pcm_hw_constraint_step(runtime, 0,
+					 SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 32);
+end:
+	return err;
+}
+EXPORT_SYMBOL(amdtp_stream_add_pcm_hw_constraints);
+
+/**
+ * amdtp_stream_set_parameters - set stream parameters
+ * @s: the AMDTP stream to configure
+ * @rate: the sample rate
+ * @data_block_quadlets: the size of a data block in quadlet unit
+ *
+ * The parameters must be set before the stream is started, and must not be
+ * changed while the stream is running.
+ */
+int amdtp_stream_set_parameters(struct amdtp_stream *s, unsigned int rate,
+				unsigned int data_block_quadlets)
+{
+	unsigned int sfc;
+
+	for (sfc = 0; sfc < ARRAY_SIZE(amdtp_rate_table); ++sfc) {
+		if (amdtp_rate_table[sfc] == rate)
+			break;
+	}
+	if (sfc == ARRAY_SIZE(amdtp_rate_table))
+		return -EINVAL;
+
+	s->sfc = sfc;
+	s->data_block_quadlets = data_block_quadlets;
+	s->syt_interval = amdtp_syt_intervals[sfc];
+
+	/* default buffering in the device */
+	s->transfer_delay = TRANSFER_DELAY_TICKS - TICKS_PER_CYCLE;
+	if (s->flags & CIP_BLOCKING)
+		/* additional buffering needed to adjust for no-data packets */
+		s->transfer_delay += TICKS_PER_SECOND * s->syt_interval / rate;
+
+	return 0;
+}
+EXPORT_SYMBOL(amdtp_stream_set_parameters);
+
+/**
+ * amdtp_stream_get_max_payload - get the stream's packet size
+ * @s: the AMDTP stream
+ *
+ * This function must not be called before the stream has been configured
+ * with amdtp_stream_set_parameters().
+ */
+unsigned int amdtp_stream_get_max_payload(struct amdtp_stream *s)
+{
+	unsigned int multiplier = 1;
+
+	if (s->flags & CIP_JUMBO_PAYLOAD)
+		multiplier = 5;
+
+	return 8 + s->syt_interval * s->data_block_quadlets * 4 * multiplier;
+}
+EXPORT_SYMBOL(amdtp_stream_get_max_payload);
+
+/**
+ * amdtp_stream_pcm_prepare - prepare PCM device for running
+ * @s: the AMDTP stream
+ *
+ * This function should be called from the PCM device's .prepare callback.
+ */
+void amdtp_stream_pcm_prepare(struct amdtp_stream *s)
+{
+	tasklet_kill(&s->period_tasklet);
+	s->pcm_buffer_pointer = 0;
+	s->pcm_period_pointer = 0;
+	s->pointer_flush = true;
+}
+EXPORT_SYMBOL(amdtp_stream_pcm_prepare);
+
+static unsigned int calculate_data_blocks(struct amdtp_stream *s,
+					  unsigned int syt)
+{
+	unsigned int phase, data_blocks;
+
+	/* Blocking mode. */
+	if (s->flags & CIP_BLOCKING) {
+		/* This module generate empty packet for 'no data'. */
+		if (syt == CIP_SYT_NO_INFO)
+			data_blocks = 0;
+		else
+			data_blocks = s->syt_interval;
+	/* Non-blocking mode. */
+	} else {
+		if (!cip_sfc_is_base_44100(s->sfc)) {
+			/* Sample_rate / 8000 is an integer, and precomputed. */
+			data_blocks = s->data_block_state;
+		} else {
+			phase = s->data_block_state;
+
+		/*
+		 * This calculates the number of data blocks per packet so that
+		 * 1) the overall rate is correct and exactly synchronized to
+		 *    the bus clock, and
+		 * 2) packets with a rounded-up number of blocks occur as early
+		 *    as possible in the sequence (to prevent underruns of the
+		 *    device's buffer).
+		 */
+			if (s->sfc == CIP_SFC_44100)
+				/* 6 6 5 6 5 6 5 ... */
+				data_blocks = 5 + ((phase & 1) ^
+						   (phase == 0 || phase >= 40));
+			else
+				/* 12 11 11 11 11 ... or 23 22 22 22 22 ... */
+				data_blocks = 11 * (s->sfc >> 1) + (phase == 0);
+			if (++phase >= (80 >> (s->sfc >> 1)))
+				phase = 0;
+			s->data_block_state = phase;
+		}
+	}
+
+	return data_blocks;
+}
+
+static unsigned int calculate_syt(struct amdtp_stream *s,
+				  unsigned int cycle)
+{
+	unsigned int syt_offset, phase, index, syt;
+
+	if (s->last_syt_offset < TICKS_PER_CYCLE) {
+		if (!cip_sfc_is_base_44100(s->sfc))
+			syt_offset = s->last_syt_offset + s->syt_offset_state;
+		else {
+		/*
+		 * The time, in ticks, of the n'th SYT_INTERVAL sample is:
+		 *   n * SYT_INTERVAL * 24576000 / sample_rate
+		 * Modulo TICKS_PER_CYCLE, the difference between successive
+		 * elements is about 1386.23.  Rounding the results of this
+		 * formula to the SYT precision results in a sequence of
+		 * differences that begins with:
+		 *   1386 1386 1387 1386 1386 1386 1387 1386 1386 1386 1387 ...
+		 * This code generates _exactly_ the same sequence.
+		 */
+			phase = s->syt_offset_state;
+			index = phase % 13;
+			syt_offset = s->last_syt_offset;
+			syt_offset += 1386 + ((index && !(index & 3)) ||
+					      phase == 146);
+			if (++phase >= 147)
+				phase = 0;
+			s->syt_offset_state = phase;
+		}
+	} else
+		syt_offset = s->last_syt_offset - TICKS_PER_CYCLE;
+	s->last_syt_offset = syt_offset;
+
+	if (syt_offset < TICKS_PER_CYCLE) {
+		syt_offset += s->transfer_delay;
+		syt = (cycle + syt_offset / TICKS_PER_CYCLE) << 12;
+		syt += syt_offset % TICKS_PER_CYCLE;
+
+		return syt & CIP_SYT_MASK;
+	} else {
+		return CIP_SYT_NO_INFO;
+	}
+}
+
+static void update_pcm_pointers(struct amdtp_stream *s,
+				struct snd_pcm_substream *pcm,
+				unsigned int frames)
+{
+	unsigned int ptr;
+
+	ptr = s->pcm_buffer_pointer + frames;
+	if (ptr >= pcm->runtime->buffer_size)
+		ptr -= pcm->runtime->buffer_size;
+	ACCESS_ONCE(s->pcm_buffer_pointer) = ptr;
+
+	s->pcm_period_pointer += frames;
+	if (s->pcm_period_pointer >= pcm->runtime->period_size) {
+		s->pcm_period_pointer -= pcm->runtime->period_size;
+		s->pointer_flush = false;
+		tasklet_hi_schedule(&s->period_tasklet);
+	}
+}
+
+static void pcm_period_tasklet(unsigned long data)
+{
+	struct amdtp_stream *s = (void *)data;
+	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+
+	if (pcm)
+		snd_pcm_period_elapsed(pcm);
+}
+
+static int queue_packet(struct amdtp_stream *s,
+			unsigned int header_length,
+			unsigned int payload_length, bool skip)
+{
+	struct fw_iso_packet p = {0};
+	int err = 0;
+
+	if (IS_ERR(s->context))
+		goto end;
+
+	p.interrupt = IS_ALIGNED(s->packet_index + 1, INTERRUPT_INTERVAL);
+	p.tag = TAG_CIP;
+	p.header_length = header_length;
+	p.payload_length = (!skip) ? payload_length : 0;
+	p.skip = skip;
+	err = fw_iso_context_queue(s->context, &p, &s->buffer.iso_buffer,
+				   s->buffer.packets[s->packet_index].offset);
+	if (err < 0) {
+		dev_err(&s->unit->device, "queueing error: %d\n", err);
+		goto end;
+	}
+
+	if (++s->packet_index >= QUEUE_LENGTH)
+		s->packet_index = 0;
+end:
+	return err;
+}
+
+static inline int queue_out_packet(struct amdtp_stream *s,
+				   unsigned int payload_length, bool skip)
+{
+	return queue_packet(s, OUT_PACKET_HEADER_SIZE,
+			    payload_length, skip);
+}
+
+static inline int queue_in_packet(struct amdtp_stream *s)
+{
+	return queue_packet(s, IN_PACKET_HEADER_SIZE,
+			    amdtp_stream_get_max_payload(s), false);
+}
+
+static int handle_out_packet(struct amdtp_stream *s, unsigned int data_blocks,
+			     unsigned int syt)
+{
+	__be32 *buffer;
+	unsigned int payload_length;
+	unsigned int pcm_frames;
+	struct snd_pcm_substream *pcm;
+
+	buffer = s->buffer.packets[s->packet_index].buffer;
+	pcm_frames = s->process_data_blocks(s, buffer + 2, data_blocks, &syt);
+
+	buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |
+				(s->data_block_quadlets << CIP_DBS_SHIFT) |
+				s->data_block_counter);
+	buffer[1] = cpu_to_be32(CIP_EOH |
+				((s->fmt << CIP_FMT_SHIFT) & CIP_FMT_MASK) |
+				((s->fdf << CIP_FDF_SHIFT) & CIP_FDF_MASK) |
+				(syt & CIP_SYT_MASK));
+
+	s->data_block_counter = (s->data_block_counter + data_blocks) & 0xff;
+
+	payload_length = 8 + data_blocks * 4 * s->data_block_quadlets;
+	if (queue_out_packet(s, payload_length, false) < 0)
+		return -EIO;
+
+	pcm = ACCESS_ONCE(s->pcm);
+	if (pcm && pcm_frames > 0)
+		update_pcm_pointers(s, pcm, pcm_frames);
+
+	/* No need to return the number of handled data blocks. */
+	return 0;
+}
+
+static int handle_in_packet(struct amdtp_stream *s,
+			    unsigned int payload_quadlets, __be32 *buffer,
+			    unsigned int *data_blocks, unsigned int syt)
+{
+	u32 cip_header[2];
+	unsigned int fmt, fdf;
+	unsigned int data_block_quadlets, data_block_counter, dbc_interval;
+	struct snd_pcm_substream *pcm;
+	unsigned int pcm_frames;
+	bool lost;
+
+	cip_header[0] = be32_to_cpu(buffer[0]);
+	cip_header[1] = be32_to_cpu(buffer[1]);
+
+	/*
+	 * This module supports 'Two-quadlet CIP header with SYT field'.
+	 * For convenience, also check FMT field is AM824 or not.
+	 */
+	if (((cip_header[0] & CIP_EOH_MASK) == CIP_EOH) ||
+	    ((cip_header[1] & CIP_EOH_MASK) != CIP_EOH)) {
+		dev_info_ratelimited(&s->unit->device,
+				"Invalid CIP header for AMDTP: %08X:%08X\n",
+				cip_header[0], cip_header[1]);
+		*data_blocks = 0;
+		pcm_frames = 0;
+		goto end;
+	}
+
+	/* Check valid protocol or not. */
+	fmt = (cip_header[1] & CIP_FMT_MASK) >> CIP_FMT_SHIFT;
+	if (fmt != s->fmt) {
+		dev_info_ratelimited(&s->unit->device,
+				     "Detect unexpected protocol: %08x %08x\n",
+				     cip_header[0], cip_header[1]);
+		*data_blocks = 0;
+		pcm_frames = 0;
+		goto end;
+	}
+
+	/* Calculate data blocks */
+	fdf = (cip_header[1] & CIP_FDF_MASK) >> CIP_FDF_SHIFT;
+	if (payload_quadlets < 3 ||
+	    (fmt == CIP_FMT_AM && fdf == AMDTP_FDF_NO_DATA)) {
+		*data_blocks = 0;
+	} else {
+		data_block_quadlets =
+			(cip_header[0] & CIP_DBS_MASK) >> CIP_DBS_SHIFT;
+		/* avoid division by zero */
+		if (data_block_quadlets == 0) {
+			dev_err(&s->unit->device,
+				"Detect invalid value in dbs field: %08X\n",
+				cip_header[0]);
+			return -EPROTO;
+		}
+		if (s->flags & CIP_WRONG_DBS)
+			data_block_quadlets = s->data_block_quadlets;
+
+		*data_blocks = (payload_quadlets - 2) / data_block_quadlets;
+	}
+
+	/* Check data block counter continuity */
+	data_block_counter = cip_header[0] & CIP_DBC_MASK;
+	if (*data_blocks == 0 && (s->flags & CIP_EMPTY_HAS_WRONG_DBC) &&
+	    s->data_block_counter != UINT_MAX)
+		data_block_counter = s->data_block_counter;
+
+	if (((s->flags & CIP_SKIP_DBC_ZERO_CHECK) &&
+	     data_block_counter == s->tx_first_dbc) ||
+	    s->data_block_counter == UINT_MAX) {
+		lost = false;
+	} else if (!(s->flags & CIP_DBC_IS_END_EVENT)) {
+		lost = data_block_counter != s->data_block_counter;
+	} else {
+		if ((*data_blocks > 0) && (s->tx_dbc_interval > 0))
+			dbc_interval = s->tx_dbc_interval;
+		else
+			dbc_interval = *data_blocks;
+
+		lost = data_block_counter !=
+		       ((s->data_block_counter + dbc_interval) & 0xff);
+	}
+
+	if (lost) {
+		dev_err(&s->unit->device,
+			"Detect discontinuity of CIP: %02X %02X\n",
+			s->data_block_counter, data_block_counter);
+		return -EIO;
+	}
+
+	pcm_frames = s->process_data_blocks(s, buffer + 2, *data_blocks, &syt);
+
+	if (s->flags & CIP_DBC_IS_END_EVENT)
+		s->data_block_counter = data_block_counter;
+	else
+		s->data_block_counter =
+				(data_block_counter + *data_blocks) & 0xff;
+end:
+	if (queue_in_packet(s) < 0)
+		return -EIO;
+
+	pcm = ACCESS_ONCE(s->pcm);
+	if (pcm && pcm_frames > 0)
+		update_pcm_pointers(s, pcm, pcm_frames);
+
+	return 0;
+}
+
+static void out_stream_callback(struct fw_iso_context *context, u32 cycle,
+				size_t header_length, void *header,
+				void *private_data)
+{
+	struct amdtp_stream *s = private_data;
+	unsigned int i, syt, packets = header_length / 4;
+	unsigned int data_blocks;
+
+	if (s->packet_index < 0)
+		return;
+
+	/*
+	 * Compute the cycle of the last queued packet.
+	 * (We need only the four lowest bits for the SYT, so we can ignore
+	 * that bits 0-11 must wrap around at 3072.)
+	 */
+	cycle += QUEUE_LENGTH - packets;
+
+	for (i = 0; i < packets; ++i) {
+		syt = calculate_syt(s, ++cycle);
+		data_blocks = calculate_data_blocks(s, syt);
+
+		if (handle_out_packet(s, data_blocks, syt) < 0) {
+			s->packet_index = -1;
+			amdtp_stream_pcm_abort(s);
+			return;
+		}
+	}
+
+	fw_iso_context_queue_flush(s->context);
+}
+
+static void in_stream_callback(struct fw_iso_context *context, u32 cycle,
+			       size_t header_length, void *header,
+			       void *private_data)
+{
+	struct amdtp_stream *s = private_data;
+	unsigned int p, syt, packets;
+	unsigned int payload_quadlets, max_payload_quadlets;
+	unsigned int data_blocks;
+	__be32 *buffer, *headers = header;
+
+	if (s->packet_index < 0)
+		return;
+
+	/* The number of packets in buffer */
+	packets = header_length / IN_PACKET_HEADER_SIZE;
+
+	/* For buffer-over-run prevention. */
+	max_payload_quadlets = amdtp_stream_get_max_payload(s) / 4;
+
+	for (p = 0; p < packets; p++) {
+		buffer = s->buffer.packets[s->packet_index].buffer;
+
+		/* The number of quadlets in this packet */
+		payload_quadlets =
+			(be32_to_cpu(headers[p]) >> ISO_DATA_LENGTH_SHIFT) / 4;
+		if (payload_quadlets > max_payload_quadlets) {
+			dev_err(&s->unit->device,
+				"Detect jumbo payload: %02x %02x\n",
+				payload_quadlets, max_payload_quadlets);
+			s->packet_index = -1;
+			break;
+		}
+
+		syt = be32_to_cpu(buffer[1]) & CIP_SYT_MASK;
+		if (handle_in_packet(s, payload_quadlets, buffer,
+						&data_blocks, syt) < 0) {
+			s->packet_index = -1;
+			break;
+		}
+
+		/* Process sync slave stream */
+		if (s->sync_slave && s->sync_slave->callbacked) {
+			if (handle_out_packet(s->sync_slave,
+					      data_blocks, syt) < 0) {
+				s->packet_index = -1;
+				break;
+			}
+		}
+	}
+
+	/* Queueing error or detecting discontinuity */
+	if (s->packet_index < 0) {
+		amdtp_stream_pcm_abort(s);
+
+		/* Abort sync slave. */
+		if (s->sync_slave) {
+			s->sync_slave->packet_index = -1;
+			amdtp_stream_pcm_abort(s->sync_slave);
+		}
+		return;
+	}
+
+	/* when sync to device, flush the packets for slave stream */
+	if (s->sync_slave && s->sync_slave->callbacked)
+		fw_iso_context_queue_flush(s->sync_slave->context);
+
+	fw_iso_context_queue_flush(s->context);
+}
+
+/* processing is done by master callback */
+static void slave_stream_callback(struct fw_iso_context *context, u32 cycle,
+				  size_t header_length, void *header,
+				  void *private_data)
+{
+	return;
+}
+
+/* this is executed one time */
+static void amdtp_stream_first_callback(struct fw_iso_context *context,
+					u32 cycle, size_t header_length,
+					void *header, void *private_data)
+{
+	struct amdtp_stream *s = private_data;
+
+	/*
+	 * For in-stream, first packet has come.
+	 * For out-stream, prepared to transmit first packet
+	 */
+	s->callbacked = true;
+	wake_up(&s->callback_wait);
+
+	if (s->direction == AMDTP_IN_STREAM)
+		context->callback.sc = in_stream_callback;
+	else if (s->flags & CIP_SYNC_TO_DEVICE)
+		context->callback.sc = slave_stream_callback;
+	else
+		context->callback.sc = out_stream_callback;
+
+	context->callback.sc(context, cycle, header_length, header, s);
+}
+
+/**
+ * amdtp_stream_start - start transferring packets
+ * @s: the AMDTP stream to start
+ * @channel: the isochronous channel on the bus
+ * @speed: firewire speed code
+ *
+ * The stream cannot be started until it has been configured with
+ * amdtp_stream_set_parameters() and it must be started before any PCM or MIDI
+ * device can be started.
+ */
+int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed)
+{
+	static const struct {
+		unsigned int data_block;
+		unsigned int syt_offset;
+	} initial_state[] = {
+		[CIP_SFC_32000]  = {  4, 3072 },
+		[CIP_SFC_48000]  = {  6, 1024 },
+		[CIP_SFC_96000]  = { 12, 1024 },
+		[CIP_SFC_192000] = { 24, 1024 },
+		[CIP_SFC_44100]  = {  0,   67 },
+		[CIP_SFC_88200]  = {  0,   67 },
+		[CIP_SFC_176400] = {  0,   67 },
+	};
+	unsigned int header_size;
+	enum dma_data_direction dir;
+	int type, tag, err;
+
+	mutex_lock(&s->mutex);
+
+	if (WARN_ON(amdtp_stream_running(s) ||
+		    (s->data_block_quadlets < 1))) {
+		err = -EBADFD;
+		goto err_unlock;
+	}
+
+	if (s->direction == AMDTP_IN_STREAM &&
+	    s->flags & CIP_SKIP_INIT_DBC_CHECK)
+		s->data_block_counter = UINT_MAX;
+	else
+		s->data_block_counter = 0;
+	s->data_block_state = initial_state[s->sfc].data_block;
+	s->syt_offset_state = initial_state[s->sfc].syt_offset;
+	s->last_syt_offset = TICKS_PER_CYCLE;
+
+	/* initialize packet buffer */
+	if (s->direction == AMDTP_IN_STREAM) {
+		dir = DMA_FROM_DEVICE;
+		type = FW_ISO_CONTEXT_RECEIVE;
+		header_size = IN_PACKET_HEADER_SIZE;
+	} else {
+		dir = DMA_TO_DEVICE;
+		type = FW_ISO_CONTEXT_TRANSMIT;
+		header_size = OUT_PACKET_HEADER_SIZE;
+	}
+	err = iso_packets_buffer_init(&s->buffer, s->unit, QUEUE_LENGTH,
+				      amdtp_stream_get_max_payload(s), dir);
+	if (err < 0)
+		goto err_unlock;
+
+	s->context = fw_iso_context_create(fw_parent_device(s->unit)->card,
+					   type, channel, speed, header_size,
+					   amdtp_stream_first_callback, s);
+	if (IS_ERR(s->context)) {
+		err = PTR_ERR(s->context);
+		if (err == -EBUSY)
+			dev_err(&s->unit->device,
+				"no free stream on this controller\n");
+		goto err_buffer;
+	}
+
+	amdtp_stream_update(s);
+
+	s->packet_index = 0;
+	do {
+		if (s->direction == AMDTP_IN_STREAM)
+			err = queue_in_packet(s);
+		else
+			err = queue_out_packet(s, 0, true);
+		if (err < 0)
+			goto err_context;
+	} while (s->packet_index > 0);
+
+	/* NOTE: TAG1 matches CIP. This just affects in stream. */
+	tag = FW_ISO_CONTEXT_MATCH_TAG1;
+	if (s->flags & CIP_EMPTY_WITH_TAG0)
+		tag |= FW_ISO_CONTEXT_MATCH_TAG0;
+
+	s->callbacked = false;
+	err = fw_iso_context_start(s->context, -1, 0, tag);
+	if (err < 0)
+		goto err_context;
+
+	mutex_unlock(&s->mutex);
+
+	return 0;
+
+err_context:
+	fw_iso_context_destroy(s->context);
+	s->context = ERR_PTR(-1);
+err_buffer:
+	iso_packets_buffer_destroy(&s->buffer, s->unit);
+err_unlock:
+	mutex_unlock(&s->mutex);
+
+	return err;
+}
+EXPORT_SYMBOL(amdtp_stream_start);
+
+/**
+ * amdtp_stream_pcm_pointer - get the PCM buffer position
+ * @s: the AMDTP stream that transports the PCM data
+ *
+ * Returns the current buffer position, in frames.
+ */
+unsigned long amdtp_stream_pcm_pointer(struct amdtp_stream *s)
+{
+	/* this optimization is allowed to be racy */
+	if (s->pointer_flush && amdtp_stream_running(s))
+		fw_iso_context_flush_completions(s->context);
+	else
+		s->pointer_flush = true;
+
+	return ACCESS_ONCE(s->pcm_buffer_pointer);
+}
+EXPORT_SYMBOL(amdtp_stream_pcm_pointer);
+
+/**
+ * amdtp_stream_update - update the stream after a bus reset
+ * @s: the AMDTP stream
+ */
+void amdtp_stream_update(struct amdtp_stream *s)
+{
+	/* Precomputing. */
+	ACCESS_ONCE(s->source_node_id_field) =
+		(fw_parent_device(s->unit)->card->node_id << CIP_SID_SHIFT) &
+								CIP_SID_MASK;
+}
+EXPORT_SYMBOL(amdtp_stream_update);
+
+/**
+ * amdtp_stream_stop - stop sending packets
+ * @s: the AMDTP stream to stop
+ *
+ * All PCM and MIDI devices of the stream must be stopped before the stream
+ * itself can be stopped.
+ */
+void amdtp_stream_stop(struct amdtp_stream *s)
+{
+	mutex_lock(&s->mutex);
+
+	if (!amdtp_stream_running(s)) {
+		mutex_unlock(&s->mutex);
+		return;
+	}
+
+	tasklet_kill(&s->period_tasklet);
+	fw_iso_context_stop(s->context);
+	fw_iso_context_destroy(s->context);
+	s->context = ERR_PTR(-1);
+	iso_packets_buffer_destroy(&s->buffer, s->unit);
+
+	s->callbacked = false;
+
+	mutex_unlock(&s->mutex);
+}
+EXPORT_SYMBOL(amdtp_stream_stop);
+
+/**
+ * amdtp_stream_pcm_abort - abort the running PCM device
+ * @s: the AMDTP stream about to be stopped
+ *
+ * If the isochronous stream needs to be stopped asynchronously, call this
+ * function first to stop the PCM device.
+ */
+void amdtp_stream_pcm_abort(struct amdtp_stream *s)
+{
+	struct snd_pcm_substream *pcm;
+
+	pcm = ACCESS_ONCE(s->pcm);
+	if (pcm)
+		snd_pcm_stop_xrun(pcm);
+}
+EXPORT_SYMBOL(amdtp_stream_pcm_abort);