path: root/sound/firewire/amdtp-stream.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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>
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.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 OHCI_MAX_SECOND		8

/* Always support Linux tracing subsystem. */
#define CREATE_TRACE_POINTS
#include "amdtp-stream-trace.h"

#define TRANSFER_DELAY_TICKS	0x2e00 /* 479.17 microseconds */

/* isochronous header parameters */
#define ISO_DATA_LENGTH_SHIFT	16
#define TAG_NO_CIP_HEADER	0
#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_SPH_MASK		0x00000400
#define CIP_SPH_SHIFT		10
#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

// For iso header, tstamp and 2 CIP header.
#define IR_CTX_HEADER_SIZE_CIP		16
// For iso header and tstamp.
#define IR_CTX_HEADER_SIZE_NO_CIP	8
#define HEADER_TSTAMP_MASK	0x0000ffff

#define IT_PKT_HEADER_SIZE_CIP		8 // For 2 CIP header.
#define IT_PKT_HEADER_SIZE_NO_CIP	0 // Nothing.

static void pcm_period_work(struct work_struct *work);

/**
 * 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_ctx_payloads: callback handler to process payloads of isoc context
 * @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_ctx_payloads_t process_ctx_payloads,
		      unsigned int protocol_size)
{
	if (process_ctx_payloads == 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);
	INIT_WORK(&s->period_work, pcm_period_work);
	s->packet_index = 0;

	init_waitqueue_head(&s->callback_wait);
	s->callbacked = false;

	s->fmt = fmt;
	s->process_ctx_payloads = process_ctx_payloads;

	if (dir == AMDTP_OUT_STREAM)
		s->ctx_data.rx.syt_override = -1;

	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)
{
	/* Not initialized. */
	if (s->protocol == NULL)
		return;

	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);

static int apply_constraint_to_size(struct snd_pcm_hw_params *params,
				    struct snd_pcm_hw_rule *rule)
{
	struct snd_interval *s = hw_param_interval(params, rule->var);
	const struct snd_interval *r =
		hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
	struct snd_interval t = {0};
	unsigned int step = 0;
	int i;

	for (i = 0; i < CIP_SFC_COUNT; ++i) {
		if (snd_interval_test(r, amdtp_rate_table[i]))
			step = max(step, amdtp_syt_intervals[i]);
	}

	t.min = roundup(s->min, step);
	t.max = rounddown(s->max, step);
	t.integer = 1;

	return snd_interval_refine(s, &t);
}

/**
 * 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)
{
	struct snd_pcm_hardware *hw = &runtime->hw;
	unsigned int ctx_header_size;
	unsigned int maximum_usec_per_period;
	int err;

	hw->info = SNDRV_PCM_INFO_BATCH |
		   SNDRV_PCM_INFO_BLOCK_TRANSFER |
		   SNDRV_PCM_INFO_INTERLEAVED |
		   SNDRV_PCM_INFO_JOINT_DUPLEX |
		   SNDRV_PCM_INFO_MMAP |
		   SNDRV_PCM_INFO_MMAP_VALID;

	/* SNDRV_PCM_INFO_BATCH */
	hw->periods_min = 2;
	hw->periods_max = UINT_MAX;

	/* bytes for a frame */
	hw->period_bytes_min = 4 * hw->channels_max;

	/* Just to prevent from allocating much pages. */
	hw->period_bytes_max = hw->period_bytes_min * 2048;
	hw->buffer_bytes_max = hw->period_bytes_max * hw->periods_min;

	// Linux driver for 1394 OHCI controller voluntarily flushes isoc
	// context when total size of accumulated context header reaches
	// PAGE_SIZE. This kicks work for the isoc context and brings
	// callback in the middle of scheduled interrupts.
	// Although AMDTP streams in the same domain use the same events per
	// IRQ, use the largest size of context header between IT/IR contexts.
	// Here, use the value of context header in IR context is for both
	// contexts.
	if (!(s->flags & CIP_NO_HEADER))
		ctx_header_size = IR_CTX_HEADER_SIZE_CIP;
	else
		ctx_header_size = IR_CTX_HEADER_SIZE_NO_CIP;
	maximum_usec_per_period = USEC_PER_SEC * PAGE_SIZE /
				  CYCLES_PER_SECOND / ctx_header_size;

	// In IEC 61883-6, one isoc packet can transfer events up to the value
	// of syt interval. This comes from the interval of isoc cycle. As 1394
	// OHCI controller can generate hardware IRQ per isoc packet, the
	// interval is 125 usec.
	// However, there are two ways of transmission in IEC 61883-6; blocking
	// and non-blocking modes. In blocking mode, the sequence of isoc packet
	// includes 'empty' or 'NODATA' packets which include no event. In
	// non-blocking mode, the number of events per packet is variable up to
	// the syt interval.
	// Due to the above protocol design, the minimum PCM frames per
	// interrupt should be double of the value of syt interval, thus it is
	// 250 usec.
	err = snd_pcm_hw_constraint_minmax(runtime,
					   SNDRV_PCM_HW_PARAM_PERIOD_TIME,
					   250, maximum_usec_per_period);
	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.
	 */
	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZ