isight.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Apple iSight audio driver
 *
 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
 */

#include <asm/byteorder.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <sound/control.h>
#include <sound/core.h>
#include <sound/initval.h>
#include <sound/pcm.h>
#include <sound/tlv.h>
#include "lib.h"
#include "iso-resources.h"
#include "packets-buffer.h"

#define OUI_APPLE		0x000a27
#define MODEL_APPLE_ISIGHT	0x000008
#define SW_ISIGHT_AUDIO		0x000010

#define REG_AUDIO_ENABLE	0x000
#define  AUDIO_ENABLE		0x80000000
#define REG_DEF_AUDIO_GAIN	0x204
#define REG_GAIN_RAW_START	0x210
#define REG_GAIN_RAW_END	0x214
#define REG_GAIN_DB_START	0x218
#define REG_GAIN_DB_END		0x21c
#define REG_SAMPLE_RATE_INQUIRY	0x280
#define REG_ISO_TX_CONFIG	0x300
#define  SPEED_SHIFT		16
#define REG_SAMPLE_RATE		0x400
#define  RATE_48000		0x80000000
#define REG_GAIN		0x500
#define REG_MUTE		0x504

#define MAX_FRAMES_PER_PACKET	475

#define QUEUE_LENGTH		20

struct isight {
	struct snd_card *card;
	struct fw_unit *unit;
	struct fw_device *device;
	u64 audio_base;
	struct snd_pcm_substream *pcm;
	struct mutex mutex;
	struct iso_packets_buffer buffer;
	struct fw_iso_resources resources;
	struct fw_iso_context *context;
	bool pcm_active;
	bool pcm_running;
	bool first_packet;
	int packet_index;
	u32 total_samples;
	unsigned int buffer_pointer;
	unsigned int period_counter;
	s32 gain_min, gain_max;
	unsigned int gain_tlv[4];
};

struct audio_payload {
	__be32 sample_count;
	__be32 signature;
	__be32 sample_total;
	__be32 reserved;
	__be16 samples[2 * MAX_FRAMES_PER_PACKET];
};

MODULE_DESCRIPTION("iSight audio driver");
MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
MODULE_LICENSE("GPL v2");

static struct fw_iso_packet audio_packet = {
	.payload_length = sizeof(struct audio_payload),
	.interrupt = 1,
	.header_length = 4,
};

static void isight_update_pointers(struct isight *isight, unsigned int count)
{
	struct snd_pcm_runtime *runtime = isight->pcm->runtime;
	unsigned int ptr;

	smp_wmb(); /* update buffer data before buffer pointer */

	ptr = isight->buffer_pointer;
	ptr += count;
	if (ptr >= runtime->buffer_size)
		ptr -= runtime->buffer_size;
	WRITE_ONCE(isight->buffer_pointer, ptr);

	isight->period_counter += count;
	if (isight->period_counter >= runtime->period_size) {
		isight->period_counter -= runtime->period_size;
		snd_pcm_period_elapsed(isight->pcm);
	}
}

static void isight_samples(struct isight *isight,
			   const __be16 *samples, unsigned int count)
{
	struct snd_pcm_runtime *runtime;
	unsigned int count1;

	if (!READ_ONCE(isight->pcm_running))
		return;

	runtime = isight->pcm->runtime;
	if (isight->buffer_pointer + count <= runtime->buffer_size) {
		memcpy(runtime->dma_area + isight->buffer_pointer * 4,
		       samples, count * 4);
	} else {
		count1 = runtime->buffer_size - isight->buffer_pointer;
		memcpy(runtime->dma_area + isight->buffer_pointer * 4,
		       samples, count1 * 4);
		samples += count1 * 2;
		memcpy(runtime->dma_area, samples, (count - count1) * 4);
	}

	isight_update_pointers(isight, count);
}

static void isight_pcm_abort(struct isight *isight)
{
	if (READ_ONCE(isight->pcm_active))
		snd_pcm_stop_xrun(isight->pcm);
}

static void isight_dropped_samples(struct isight *isight, unsigned int total)
{
	struct snd_pcm_runtime *runtime;
	u32 dropped;
	unsigned int count1;

	if (!READ_ONCE(isight->pcm_running))
		return;

	runtime = isight->pcm->runtime;
	dropped = total - isight->total_samples;
	if (dropped < runtime->buffer_size) {
		if (isight->buffer_pointer + dropped <= runtime->buffer_size) {
			memset(runtime->dma_area + isight->buffer_pointer * 4,
			       0, dropped * 4);
		} else {
			count1 = runtime->buffer_size - isight->buffer_pointer;
			memset(runtime->dma_area + isight->buffer_pointer * 4,
			       0, count1 * 4);
			memset(runtime->dma_area, 0, (dropped - count1) * 4);
		}
		isight_update_pointers(isight, dropped);
	} else {
		isight_pcm_abort(isight);
	}
}

static void isight_packet(struct fw_iso_context *context, u32 cycle,
			  size_t header_length, void *header, void *data)
{
	struct isight *isight = data;
	const struct audio_payload *payload;
	unsigned int index, length, count, total;
	int err;

	if (isight->packet_index < 0)
		return;
	index = isight->packet_index;
	payload = isight->buffer.packets[index].buffer;
	length = be32_to_cpup(header) >> 16;

	if (likely(length >= 16 &&
		   payload->signature == cpu_to_be32(0x73676874/*"sght"*/))) {
		count = be32_to_cpu(payload->sample_count);
		if (likely(count <= (length - 16) / 4)) {
			total = be32_to_cpu(payload->sample_total);
			if (unlikely(total != isight->total_samples)) {
				if (!isight->first_packet)
					isight_dropped_samples(isight, total);
				isight->first_packet = false;
				isight->total_samples = total;
			}

			isight_samples(isight, payload->samples, count);
			isight->total_samples += count;
		}
	}

	err = fw_iso_context_queue(isight->context, &audio_packet,
				   &isight->buffer.iso_buffer,
				   isight->buffer.packets[index].offset);
	if (err < 0) {
		dev_err(&isight->unit->device, "queueing error: %d\n", err);
		isight_pcm_abort(isight);
		isight->packet_index = -1;
		return;
	}
	fw_iso_context_queue_flush(isight->context);

	if (++index >= QUEUE_LENGTH)
		index = 0;
	isight->packet_index = index;
}

static int isight_connect(struct isight *isight)
{
	int ch, err;
	__be32 value;

retry_after_bus_reset:
	ch = fw_iso_resources_allocate(&isight->resources,
				       sizeof(struct audio_payload),
				       isight->device->max_speed);
	if (ch < 0) {
		err = ch;
		goto error;
	}

	value = cpu_to_be32(ch | (isight->device->max_speed << SPEED_SHIFT));
	err = snd_fw_transaction(isight->unit, TCODE_WRITE_QUADLET_REQUEST,
				 isight->audio_base + REG_ISO_TX_CONFIG,
				 &value, 4, FW_FIXED_GENERATION |
				 isight->resources.generation);
	if (err == -EAGAIN) {
		fw_iso_resources_free(&isight->resources);
		goto retry_after_bus_reset;
	} else if (err < 0) {
		goto err_resources;
	}

	return 0;

err_resources:
	fw_iso_resources_free(&isight->resources);
error:
	return err;
}

static int isight_open(struct snd_pcm_substream *substream)
{
	static const struct snd_pcm_hardware hardware = {
		.info = SNDRV_PCM_INFO_MMAP |
			SNDRV_PCM_INFO_MMAP_VALID |
			SNDRV_PCM_INFO_BATCH |
			SNDRV_PCM_INFO_INTERLEAVED |
			SNDRV_PCM_INFO_BLOCK_TRANSFER,
		.formats = SNDRV_PCM_FMTBIT_S16_BE,
		.rates = SNDRV_PCM_RATE_48000,
		.rate_min = 48000,
		.rate_max = 48000,
		.channels_min = 2,
		.channels_max = 2,
		.buffer_bytes_max = 4 * 1024 * 1024,
		.period_bytes_min = MAX_FRAMES_PER_PACKET * 4,
		.period_bytes_max = 1024 * 1024,
		.periods_min = 2,
		.periods_max = UINT_MAX,
	};
	struct isight *isight = substream->private_data;

	substream->runtime->hw = hardware;

	return iso_packets_buffer_init(&isight->buffer, isight->unit,
				       QUEUE_LENGTH,
				       sizeof(struct audio_payload),
				       DMA_FROM_DEVICE);
}

static int isight_close(struct snd_pcm_substream *substream)
{
	struct isight *isight = substream->private_data;

	iso_packets_buffer_destroy(&isight->buffer, isight->unit);

	return 0;
}

static int isight_hw_params(struct snd_pcm_substream *substream,
			    struct snd_pcm_hw_params *hw_params)
{
	struct isight *isight = substream->private_data;

	WRITE_ONCE(isight->pcm_active, true);

	return 0;
}

static int reg_read(struct isight *isight, int offset, __be32 *value)
{
	return snd_fw_transaction(isight->unit, TCODE_READ_QUADLET_REQUEST,
				  isight->audio_base + offset, value, 4, 0);
}

static int reg_write(struct isight *isight, int offset, __be32 value)
{
	return snd_fw_transaction(isight->unit, TCODE_WRITE_QUADLET_REQUEST,
				  isight->audio_base + offset, &value, 4, 0);
}

static void isight_stop_streaming(struct isight *isight)
{
	__be32 value;

	if (!isight->context)
		return;

	fw_iso_context_stop(isight->context);
	fw_iso_context_destroy(isight->context);
	isight->context = NULL;
	fw_iso_resources_free(&isight->resources);
	value = 0;
	snd_fw_transaction(isight->unit, TCODE_WRITE_QUADLET_REQUEST,
			   isight->audio_base + REG_AUDIO_ENABLE,
			   &value, 4, FW_QUIET);
}

static int isight_hw_free(struct snd_pcm_substream *substream)
{
	struct isight *isight = substream->private_data;

	WRITE_ONCE(isight->pcm_active, false);

	mutex_lock(&isight->mutex);
	isight_stop_streaming(isight);
	mutex_unlock(&isight->mutex);

	return 0;
}

static int isight_start_streaming(struct isight *isight)
{
	unsigned int i;
	int err;

	if (isight->context) {
		if (isight->packet_index < 0)
			isight_stop_streaming(isight);
		else
			return 0;
	}

	err = reg_write(isight, REG_SAMPLE_RATE, cpu_to_be32(RATE_48000));
	if (err < 0)
		goto error;

	err = isight_connect(isight);
	if (err < 0)
		goto error;

	err = reg_write(isight, REG_AUDIO_ENABLE, cpu_to_be32(AUDIO_ENABLE));
	if (err < 0)
		goto err_resources;

	isight->context = fw_iso_context_create(isight->device->card,
						FW_ISO_CONTEXT_RECEIVE,
						isight->resources.channel,
						isight->device->max_speed,
						4, isight_packet, isight);
	if (IS_ERR(isight->context)) {
		err = PTR_ERR(isight->context);
		isight->context = NULL;
		goto err_resources;
	}

	for (i = 0; i < QUEUE_LENGTH; ++i) {
		err = fw_iso_context_queue(isight->context, &audio_packet,
					   &isight->buffer.iso_buffer,
					   isight->buffer.packets[i].offset);
		if (err < 0)
			goto err_context;
	}

	isight->first_packet = true;
	isight->packet_index = 0;

	err = fw_iso_context_start(isight->context, -1, 0,
				   FW_ISO_CONTEXT_MATCH_ALL_TAGS/*?*/);
	if (err < 0)
		goto err_context;

	return 0;

err_context:
	fw_iso_context_destroy(isight->context);
	isight->context = NULL;
err_resources:
	fw_iso_resources_free(&isight->resources);
	reg_write(isight, REG_AUDIO_ENABLE, 0);
error:
	return err;
}

static int isight_prepare(struct snd_pcm_substream *substream)
{
	struct isight *isight = substream->private_data;
	int err;

	isight->buffer_pointer = 0;
	isight->period_counter = 0;

	mutex_lock(&isight->mutex);
	err = isight_start_streaming(isight);
	mutex_unlock(&isight->mutex);

	return err;
}

static int isight_trigger(struct snd_pcm_substream *substream, int cmd)
{
	struct isight *isight = substream->private_data;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
		WRITE_ONCE(isight->pcm_running, true);
		break;
	case SNDRV_PCM_TRIGGER_STOP:
		WRITE_ONCE(isight->pcm_running, false);
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

static snd_pcm_uframes_t isight_pointer(struct snd_pcm_substream *substream)
{
	struct isight *isight = substream->private_data;

	return READ_ONCE(isight->buffer_pointer);
}

static int isight_create_pcm(struct isight *isight)
{
	static const struct snd_pcm_ops ops = {
		.open      = isight_open,
		.close     = isight_close,
		.hw_params = isight_hw_params,
		.hw_free   = isight_hw_free,
		.prepare   = isight_prepare,
		.trigger   = isight_trigger,
		.pointer   = isight_pointer,
	};
	struct snd_pcm *pcm;
	int err;

	err = snd_pcm_new(isight->card, "iSight", 0, 0, 1, &pcm);
	if (err < 0)
		return err;
	pcm->private_data = isight;
	strcpy(pcm->name, "iSight");
	isight->pcm = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
	isight->pcm->ops = &ops;
	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);

	return 0;
}

static int isight_gain_info(struct snd_kcontrol *ctl,
			    struct snd_ctl_elem_info *info)
{
	struct isight *isight = ctl->private_data;

	info->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
	info->count = 1;
	info->value.integer.min = isight->gain_min;
	info->value.integer.max = isight->gain_max;

	return 0;
}

static int isight_gain_get(struct snd_kcontrol *ctl,
			   struct snd_ctl_elem_value *value)
{
	struct isight *isight = ctl->private_data;
	__be32 gain;
	int err;

	err = reg_read(isight, REG_GAIN, &gain);
	if (err < 0)
		return err;

	value->value.integer.value[0] = (s32)be32_to_cpu(gain);

	return 0;
}

static int isight_gain_put(struct snd_kcontrol *ctl,
			   struct snd_ctl_elem_value *value)
{
	struct isight *isight = ctl->private_data;

	if (value->value.integer.value[0] < isight->gain_min ||
	    value->value.integer.value[0] > isight->gain_max)
		return -EINVAL;

	return reg_write(isight, REG_GAIN,
			 cpu_to_be32(value->value.integer.value[0]));
}

static int isight_mute_get(struct snd_kcontrol *ctl,
			   struct snd_ctl_elem_value *value)
{
	struct isight *isight = ctl->private_data;
	__be32 mute;
	int err;

	err = reg_read(isight, REG_MUTE, &mute);
	if (err < 0)
		return err;

	value->value.integer.value[0] = !mute;

	return 0;
}

static int isight_mute_put(struct snd_kcontrol *ctl,
			   struct snd_ctl_elem_value *value)
{
	struct isight *isight = ctl->private_data;

	return reg_write(isight, REG_MUTE,
			 (__force __be32)!value->value.integer.value[0]);
}

static int isight_create_mixer(struct isight *isight)
{
	static const struct snd_kcontrol_new gain_control = {
		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
		.name = "Mic Capture Volume",
		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
			  SNDRV_CTL_ELEM_ACCESS_TLV_READ,
		.info = isight_gain_info,
		.get = isight_gain_get,
		.put = isight_gain_put,
	};
	static const struct snd_kcontrol_new mute_control = {
		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
		.name = "Mic Capture Switch",
		.info = snd_ctl_boolean_mono_info,
		.get = isight_mute_get,
		.put = isight_mute_put,
	};
	__be32 value;
	struct snd_kcontrol *ctl;
	int err;

	err = reg_read(isight, REG_GAIN_RAW_START, &value);
	if (err < 0)
		return err;
	isight->gain_min = be32_to_cpu(value);

	err = reg_read(isight, REG_GAIN_RAW_END, &value);
	if (err < 0)
		return err;
	isight->gain_max = be32_to_cpu(value);

	isight->gain_tlv[SNDRV_CTL_TLVO_TYPE] = SNDRV_CTL_TLVT_DB_MINMAX;
	isight->gain_tlv[SNDRV_CTL_TLVO_LEN] = 2 * sizeof(unsigned int);

	err = reg_read(isight, REG_GAIN_DB_START, &value);
	if (err < 0)
		return err;
	isight->gain_tlv[SNDRV_CTL_TLVO_DB_MINMAX_MIN] =
						(s32)be32_to_cpu(value) * 100;

	err = reg_read(isight, REG_GAIN_DB_END, &value);
	if (err < 0)
		return err;
	isight->gain_tlv[SNDRV_CTL_TLVO_DB_MINMAX_MAX] =
						(s32)be32_to_cpu(value) * 100;

	ctl = snd_ctl_new1(&gain_control, isight);
	if (ctl)
		ctl->tlv.p = isight->gain_tlv;
	err = snd_ctl_add(isight->card, ctl);
	if (err < 0)
		return err;

	err = snd_ctl_add(isight->card, snd_ctl_new1(&mute_control, isight));
	if (err < 0)
		return err;

	return 0;
}

static void isight_card_free(struct snd_card *card)
{
	struct isight *isight = card->private_data;

	fw_iso_resources_destroy(&isight->resources);
}

static u64 get_unit_base(struct fw_unit *unit)
{
	struct fw_csr_iterator i;
	int key, value;

	fw_csr_iterator_init(&i, unit->directory);
	while (fw_csr_iterator_next(&i, &key, &value))
		if (key == CSR_OFFSET)
			return CSR_REGISTER_BASE + value * 4;
	return 0;
}

static int isight_probe(struct fw_unit *unit,
			const struct ieee1394_device_id *id)
{
	struct fw_device *fw_dev = fw_parent_device(unit);
	struct snd_card *card;
	struct isight *isight;
	int err;

	err = snd_card_new(&unit->device, -1, NULL, THIS_MODULE,
			   sizeof(*isight), &card);
	if (err < 0)
		return err;

	isight = card->private_data;
	isight->card = card;
	mutex_init(&isight->mutex);
	isight->unit = fw_unit_get(unit);
	isight->device = fw_dev;
	isight->audio_base = get_unit_base(unit);
	if (!isight->audio_base) {
		dev_err(&unit->device, "audio unit base not found\n");
		err = -ENXIO;
		goto error;
	}
	fw_iso_resources_init(&isight->resources, unit);

	card->private_free = isight_card_free;

	strcpy(card->driver, "iSight");
	strcpy(card->shortname, "Apple iSight");
	snprintf(card->longname, sizeof(card->longname),
		 "Apple iSight (GUID %08x%08x) at %s, S%d",
		 fw_dev->config_rom[3], fw_dev->config_rom[4],
		 dev_name(&unit->device), 100 << fw_dev->max_speed);
	strcpy(card->mixername, "iSight");

	err = isight_create_pcm(isight);
	if (err < 0)
		goto error;

	err = isight_create_mixer(isight);
	if (err < 0)
		goto error;

	err = snd_card_register(card);
	if (err < 0)
		goto error;

	dev_set_drvdata(&unit->device, isight);

	return 0;
error:
	snd_card_free(card);

	mutex_destroy(&isight->mutex);
	fw_unit_put(isight->unit);

	return err;
}

static void isight_bus_reset(struct fw_unit *unit)
{
	struct isight *isight = dev_get_drvdata(&unit->device);

	if (fw_iso_resources_update(&isight->resources) < 0) {
		isight_pcm_abort(isight);

		mutex_lock(&isight->mutex);
		isight_stop_streaming(isight);
		mutex_unlock(&isight->mutex);
	}
}

static void isight_remove(struct fw_unit *unit)
{
	struct isight *isight = dev_get_drvdata(&unit->device);

	isight_pcm_abort(isight);

	snd_card_disconnect(isight->card);

	mutex_lock(&isight->mutex);
	isight_stop_streaming(isight);
	mutex_unlock(&isight->mutex);

	// Block till all of ALSA character devices are released.
	snd_card_free(isight->card);

	mutex_destroy(&isight->mutex);
	fw_unit_put(isight->unit);
}

static const struct ieee1394_device_id isight_id_table[] = {
	{
		.match_flags  = IEEE1394_MATCH_SPECIFIER_ID |
				IEEE1394_MATCH_VERSION,
		.specifier_id = OUI_APPLE,
		.version      = SW_ISIGHT_AUDIO,
	},
	{ }
};
MODULE_DEVICE_TABLE(ieee1394, isight_id_table);

static struct fw_driver isight_driver = {
	.driver   = {
		.owner	= THIS_MODULE,
		.name	= KBUILD_MODNAME,
		.bus	= &fw_bus_type,
	},
	.probe    = isight_probe,
	.update   = isight_bus_reset,
	.remove   = isight_remove,
	.id_table = isight_id_table,
};

static int __init alsa_isight_init(void)
{
	return driver_register(&isight_driver.driver);
}

static void __exit alsa_isight_exit(void)
{
	driver_unregister(&isight_driver.driver);
}

module_init(alsa_isight_init);
module_exit(alsa_isight_exit);