/*
 * ALSA SoC Synopsys PIO PCM for I2S driver
 *
 * sound/soc/dwc/designware_pcm.c
 *
 * Copyright (C) 2016 Synopsys
 * Jose Abreu <joabreu@synopsys.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/io.h>
#include <linux/rcupdate.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include "local.h"

#define BUFFER_BYTES_MAX	(3 * 2 * 8 * PERIOD_BYTES_MIN)
#define PERIOD_BYTES_MIN	4096
#define PERIODS_MIN		2

#define dw_pcm_tx_fn(sample_bits) \
static unsigned int dw_pcm_tx_##sample_bits(struct dw_i2s_dev *dev, \
		struct snd_pcm_runtime *runtime, unsigned int tx_ptr, \
		bool *period_elapsed) \
{ \
	const u##sample_bits (*p)[2] = (void *)runtime->dma_area; \
	unsigned int period_pos = tx_ptr % runtime->period_size; \
	int i; \
\
	for (i = 0; i < dev->fifo_th; i++) { \
		iowrite32(p[tx_ptr][0], dev->i2s_base + LRBR_LTHR(0)); \
		iowrite32(p[tx_ptr][1], dev->i2s_base + RRBR_RTHR(0)); \
		period_pos++; \
		if (++tx_ptr >= runtime->buffer_size) \
			tx_ptr = 0; \
	} \
	*period_elapsed = period_pos >= runtime->period_size; \
	return tx_ptr; \
}

#define dw_pcm_rx_fn(sample_bits) \
static unsigned int dw_pcm_rx_##sample_bits(struct dw_i2s_dev *dev, \
		struct snd_pcm_runtime *runtime, unsigned int rx_ptr, \
		bool *period_elapsed) \
{ \
	u##sample_bits (*p)[2] = (void *)runtime->dma_area; \
	unsigned int period_pos = rx_ptr % runtime->period_size; \
	int i; \
\
	for (i = 0; i < dev->fifo_th; i++) { \
		p[rx_ptr][0] = ioread32(dev->i2s_base + LRBR_LTHR(0)); \
		p[rx_ptr][1] = ioread32(dev->i2s_base + RRBR_RTHR(0)); \
		period_pos++; \
		if (++rx_ptr >= runtime->buffer_size) \
			rx_ptr = 0; \
	} \
	*period_elapsed = period_pos >= runtime->period_size; \
	return rx_ptr; \
}

dw_pcm_tx_fn(16);
dw_pcm_tx_fn(32);
dw_pcm_rx_fn(16);
dw_pcm_rx_fn(32);

#undef dw_pcm_tx_fn
#undef dw_pcm_rx_fn

static const struct snd_pcm_hardware dw_pcm_hardware = {
	.info = SNDRV_PCM_INFO_INTERLEAVED |
		SNDRV_PCM_INFO_MMAP |
		SNDRV_PCM_INFO_MMAP_VALID |
		SNDRV_PCM_INFO_BLOCK_TRANSFER,
	.rates = SNDRV_PCM_RATE_32000 |
		SNDRV_PCM_RATE_44100 |
		SNDRV_PCM_RATE_48000,
	.rate_min = 32000,
	.rate_max = 48000,
	.formats = SNDRV_PCM_FMTBIT_S16_LE |
		SNDRV_PCM_FMTBIT_S24_LE |
		SNDRV_PCM_FMTBIT_S32_LE,
	.channels_min = 2,
	.channels_max = 2,
	.buffer_bytes_max = BUFFER_BYTES_MAX,
	.period_bytes_min = PERIOD_BYTES_MIN,
	.period_bytes_max = BUFFER_BYTES_MAX / PERIODS_MIN,
	.periods_min = PERIODS_MIN,
	.periods_max = BUFFER_BYTES_MAX / PERIOD_BYTES_MIN,
	.fifo_size = 16,
};

static void dw_pcm_transfer(struct dw_i2s_dev *dev, bool push)
{
	struct snd_pcm_substream *substream;
	bool active, period_elapsed;

	rcu_read_lock();
	if (push)
		substream = rcu_dereference(dev->tx_substream);
	else
		substream = rcu_dereference(dev->rx_substream);
	active = substream && snd_pcm_running(substream);
	if (active) {
		unsigned int ptr;
		unsigned int new_ptr;

		if (push) {
			ptr = READ_ONCE(dev->tx_ptr);
			new_ptr = dev->tx_fn(dev, substream->runtime, ptr,
					&period_elapsed);
			cmpxchg(&dev->tx_ptr, ptr, new_ptr);
		} else {
			ptr = READ_ONCE(dev->rx_ptr);
			new_ptr = dev->rx_fn(dev, substream->runtime, ptr,
					&period_elapsed);
			cmpxchg(&dev->rx_ptr, ptr, new_ptr);
		}

		if (period_elapsed)
			snd_pcm_period_elapsed(substream);
	}
	rcu_read_unlock();
}

void dw_pcm_push_tx(struct dw_i2s_dev *dev)
{
	dw_pcm_transfer(dev, true);
}

void dw_pcm_pop_rx(struct dw_i2s_dev *dev)
{
	dw_pcm_transfer(dev, false);
}

static int dw_pcm_open(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct dw_i2s_dev *dev = snd_soc_dai_get_drvdata(rtd->cpu_dai);

	snd_soc_set_runtime_hwparams(substream, &dw_pcm_hardware);
	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
	runtime->private_data = dev;

	return 0;
}

static int dw_pcm_close(struct snd_pcm_substream *substream)
{
	synchronize_rcu();
	return 0;
}

static int dw_pcm_hw_params(struct snd_pcm_substream *substream,
		struct snd_pcm_hw_params *hw_params)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct dw_i2s_dev *dev = runtime->private_data;
	int ret;

	switch (params_channels(hw_params)) {
	case 2:
		break;
	default:
		dev_err(dev->dev, "invalid channels number\n");
		return -EINVAL;
	}

	switch (params_format(hw_params)) {
	case SNDRV_PCM_FORMAT_S16_LE:
		dev->tx_fn = dw_pcm_tx_16;
		dev->rx_fn = dw_pcm_rx_16;
		break;
	case SNDRV_PCM_FORMAT_S24_LE:
	case SNDRV_PCM_FORMAT_S32_LE:
		dev->tx_fn = dw_pcm_tx_32;
		dev->rx_fn = dw_pcm_rx_32;
		break;
	default:
		dev_err(dev->dev, "invalid format\n");
		return -EINVAL;
	}

	ret = snd_pcm_lib_malloc_pages(substream,
			params_buffer_bytes(hw_params));
	if (ret < 0)
		return ret;
	else
		return 0;
}

static int dw_pcm_hw_free(struct snd_pcm_substream *substream)
{
	return snd_pcm_lib_free_pages(substream);
}

static int dw_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct dw_i2s_dev *dev = runtime->private_data;
	int ret = 0;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	case SNDRV_PCM_TRIGGER_RESUME:
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
			WRITE_ONCE(dev->tx_ptr, 0);
			rcu_assign_pointer(dev->tx_substream, substream);
		} else {
			WRITE_ONCE(dev->rx_ptr, 0);
			rcu_assign_pointer(dev->rx_substream, substream);
		}
		break;
	case SNDRV_PCM_TRIGGER_STOP:
	case SNDRV_PCM_TRIGGER_SUSPEND:
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
			rcu_assign_pointer(dev->tx_substream, NULL);
		else
			rcu_assign_pointer(dev->rx_substream, NULL);
		break;
	default:
		ret = -EINVAL;
		break;
	}

	return ret;
}

static snd_pcm_uframes_t dw_pcm_pointer(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct dw_i2s_dev *dev = runtime->private_data;
	snd_pcm_uframes_t pos;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
		pos = READ_ONCE(dev->tx_ptr);
	else
		pos = READ_ONCE(dev->rx_ptr);

	return pos < runtime->buffer_size ? pos : 0;
}

static int dw_pcm_new(struct snd_soc_pcm_runtime *rtd)
{
	size_t size = dw_pcm_hardware.buffer_bytes_max;

	return snd_pcm_lib_preallocate_pages_for_all(rtd->pcm,
			SNDRV_DMA_TYPE_CONTINUOUS,
			snd_dma_continuous_data(GFP_KERNEL), size, size);
}

static void dw_pcm_free(struct snd_pcm *pcm)
{
	snd_pcm_lib_preallocate_free_for_all(pcm);
}

static const struct snd_pcm_ops dw_pcm_ops = {
	.open = dw_pcm_open,
	.close = dw_pcm_close,
	.ioctl = snd_pcm_lib_ioctl,
	.hw_params = dw_pcm_hw_params,
	.hw_free = dw_pcm_hw_free,
	.trigger = dw_pcm_trigger,
	.pointer = dw_pcm_pointer,
};

static const struct snd_soc_platform_driver dw_pcm_platform = {
	.pcm_new = dw_pcm_new,
	.pcm_free = dw_pcm_free,
	.ops = &dw_pcm_ops,
};

int dw_pcm_register(struct platform_device *pdev)
{
	return devm_snd_soc_register_platform(&pdev->dev, &dw_pcm_platform);
}