path: root/sound/atmel/ac97c.c

/*
 * Driver for Atmel AC97C
 *
 * Copyright (C) 2005-2009 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/bitmap.h>
#include <linux/device.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/gpio.h>
#include <linux/io.h>

#include <sound/core.h>
#include <sound/initval.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/ac97_codec.h>
#include <sound/atmel-ac97c.h>
#include <sound/memalloc.h>

#include <linux/dw_dmac.h>

#include "ac97c.h"

enum {
	DMA_TX_READY = 0,
	DMA_RX_READY,
	DMA_TX_CHAN_PRESENT,
	DMA_RX_CHAN_PRESENT,
};

/* Serialize access to opened variable */
static DEFINE_MUTEX(opened_mutex);

struct atmel_ac97c_dma {
	struct dma_chan			*rx_chan;
	struct dma_chan			*tx_chan;
};

struct atmel_ac97c {
	struct clk			*pclk;
	struct platform_device		*pdev;
	struct atmel_ac97c_dma		dma;

	struct snd_pcm_substream	*playback_substream;
	struct snd_pcm_substream	*capture_substream;
	struct snd_card			*card;
	struct snd_pcm			*pcm;
	struct snd_ac97			*ac97;
	struct snd_ac97_bus		*ac97_bus;

	u64				cur_format;
	unsigned int			cur_rate;
	unsigned long			flags;
	/* Serialize access to opened variable */
	spinlock_t			lock;
	void __iomem			*regs;
	int				irq;
	int				opened;
	int				reset_pin;
};

#define get_chip(card) ((struct atmel_ac97c *)(card)->private_data)

#define ac97c_writel(chip, reg, val)			\
	__raw_writel((val), (chip)->regs + AC97C_##reg)
#define ac97c_readl(chip, reg)				\
	__raw_readl((chip)->regs + AC97C_##reg)

/* This function is called by the DMA driver. */
static void atmel_ac97c_dma_playback_period_done(void *arg)
{
	struct atmel_ac97c *chip = arg;
	snd_pcm_period_elapsed(chip->playback_substream);
}

static void atmel_ac97c_dma_capture_period_done(void *arg)
{
	struct atmel_ac97c *chip = arg;
	snd_pcm_period_elapsed(chip->capture_substream);
}

static int atmel_ac97c_prepare_dma(struct atmel_ac97c *chip,
		struct snd_pcm_substream *substream,
		enum dma_data_direction direction)
{
	struct dma_chan			*chan;
	struct dw_cyclic_desc		*cdesc;
	struct snd_pcm_runtime		*runtime = substream->runtime;
	unsigned long			buffer_len, period_len;

	/*
	 * We don't do DMA on "complex" transfers, i.e. with
	 * non-halfword-aligned buffers or lengths.
	 */
	if (runtime->dma_addr & 1 || runtime->buffer_size & 1) {
		dev_dbg(&chip->pdev->dev, "too complex transfer\n");
		return -EINVAL;
	}

	if (direction == DMA_TO_DEVICE)
		chan = chip->dma.tx_chan;
	else
		chan = chip->dma.rx_chan;

	buffer_len = frames_to_bytes(runtime, runtime->buffer_size);
	period_len = frames_to_bytes(runtime, runtime->period_size);

	cdesc = dw_dma_cyclic_prep(chan, runtime->dma_addr, buffer_len,
			period_len, direction);
	if (IS_ERR(cdesc)) {
		dev_dbg(&chip->pdev->dev, "could not prepare cyclic DMA\n");
		return PTR_ERR(cdesc);
	}

	if (direction == DMA_TO_DEVICE) {
		cdesc->period_callback = atmel_ac97c_dma_playback_period_done;
		set_bit(DMA_TX_READY, &chip->flags);
	} else {
		cdesc->period_callback = atmel_ac97c_dma_capture_period_done;
		set_bit(DMA_RX_READY, &chip->flags);
	}

	cdesc->period_callback_param = chip;

	return 0;
}

static struct snd_pcm_hardware atmel_ac97c_hw = {
	.info			= (SNDRV_PCM_INFO_MMAP
				  | SNDRV_PCM_INFO_MMAP_VALID
				  | SNDRV_PCM_INFO_INTERLEAVED
				  | SNDRV_PCM_INFO_BLOCK_TRANSFER
				  | SNDRV_PCM_INFO_JOINT_DUPLEX
				  | SNDRV_PCM_INFO_RESUME
				  | SNDRV_PCM_INFO_PAUSE),
	.formats		= (SNDRV_PCM_FMTBIT_S16_BE
				  | SNDRV_PCM_FMTBIT_S16_LE),
	.rates			= (SNDRV_PCM_RATE_CONTINUOUS),
	.rate_min		= 4000,
	.rate_max		= 48000,
	.channels_min		= 1,
	.channels_max		= 2,
	.buffer_bytes_max	= 2 * 2 * 64 * 2048,
	.period_bytes_min	= 4096,
	.period_bytes_max	= 4096,
	.periods_min		= 6,
	.periods_max		= 64,
};

static int atmel_ac97c_playback_open(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;

	mutex_lock(&opened_mutex);
	chip->opened++;
	runtime->hw = atmel_ac97c_hw;
	if (chip->cur_rate) {
		runtime->hw.rate_min = chip->cur_rate;
		runtime->hw.rate_max = chip->cur_rate;
	}
	if (chip->cur_format)
		runtime->hw.formats = (1ULL << chip->cur_format);
	mutex_unlock(&opened_mutex);
	chip->playback_substream = substream;
	return 0;
}

static int atmel_ac97c_capture_open(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;

	mutex_lock(&opened_mutex);
	chip->opened++;
	runtime->hw = atmel_ac97c_hw;
	if (chip->cur_rate) {
		runtime->hw.rate_min = chip->cur_rate;
		runtime->hw.rate_max = chip->cur_rate;
	}
	if (chip->cur_format)
		runtime->hw.formats = (1ULL << chip->cur_format);
	mutex_unlock(&opened_mutex);
	chip->capture_substream = substream;
	return 0;
}

static int atmel_ac97c_playback_close(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);

	mutex_lock(&opened_mutex);
	chip->opened--;
	if (!chip->opened) {
		chip->cur_rate = 0;
		chip->cur_format = 0;
	}
	mutex_unlock(&opened_mutex);

	chip->playback_substream = NULL;

	return 0;
}

static int atmel_ac97c_capture_close(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);

	mutex_lock(&opened_mutex);
	chip->opened--;
	if (!chip->opened) {
		chip->cur_rate = 0;
		chip->cur_format = 0;
	}
	mutex_unlock(&opened_mutex);

	chip->capture_substream = NULL;

	return 0;
}

static int atmel_ac97c_playback_hw_params(struct snd_pcm_substream *substream,
		struct snd_pcm_hw_params *hw_params)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	int retval;

	retval = snd_pcm_lib_malloc_pages(substream,
					params_buffer_bytes(hw_params));
	if (retval < 0)
		return retval;
	/* snd_pcm_lib_malloc_pages returns 1 if buffer is changed. */
	if (retval == 1)
		if (test_and_clear_bit(DMA_TX_READY, &chip->flags))
			dw_dma_cyclic_free(chip->dma.tx_chan);

	/* Set restrictions to params. */
	mutex_lock(&opened_mutex);
	chip->cur_rate = params_rate(hw_params);
	chip->cur_format = params_format(hw_params);
	mutex_unlock(&opened_mutex);

	return retval;
}

static int atmel_ac97c_capture_hw_params(struct snd_pcm_substream *substream,
		struct snd_pcm_hw_params *hw_params)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	int retval;

	retval = snd_pcm_lib_malloc_pages(substream,
					params_buffer_bytes(hw_params));
	if (retval < 0)
		return retval;
	/* snd_pcm_lib_malloc_pages returns 1 if buffer is changed. */
	if (retval == 1)
		if (test_and_clear_bit(DMA_RX_READY, &chip->flags))
			dw_dma_cyclic_free(chip->dma.rx_chan);

	/* Set restrictions to params. */
	mutex_lock(&opened_mutex);
	chip->cur_rate = params_rate(hw_params);
	chip->cur_format = params_format(hw_params);
	mutex_unlock(&opened_mutex);

	return retval;
}

static int atmel_ac97c_playback_hw_free(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	if (test_and_clear_bit(DMA_TX_READY, &chip->flags))
		dw_dma_cyclic_free(chip->dma.tx_chan);
	return snd_pcm_lib_free_pages(substream);
}

static int atmel_ac97c_capture_hw_free(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	if (test_and_clear_bit(DMA_RX_READY, &chip->flags))
		dw_dma_cyclic_free(chip->dma.rx_chan);
	return snd_pcm_lib_free_pages(substream);
}

static int atmel_ac97c_playback_prepare(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;
	unsigned long word = ac97c_readl(chip, OCA);
	int retval;

	word &= ~(AC97C_CH_MASK(PCM_LEFT) | AC97C_CH_MASK(PCM_RIGHT));

	/* assign channels to AC97C channel A */
	switch (runtime->channels) {
	case 1:
		word |= AC97C_CH_ASSIGN(PCM_LEFT, A);
		break;
	case 2:
		word |= AC97C_CH_ASSIGN(PCM_LEFT, A)
			| AC97C_CH_ASSIGN(PCM_RIGHT, A);
		break;
	default:
		/* TODO: support more than two channels */
		return -EINVAL;
	}
	ac97c_writel(chip, OCA, word);

	/* configure sample format and size */
	word = AC97C_CMR_DMAEN | AC97C_CMR_SIZE_16;

	switch (runtime->format) {
	case SNDRV_PCM_FORMAT_S16_LE:
		word |= AC97C_CMR_CEM_LITTLE;
		break;
	case SNDRV_PCM_FORMAT_S16_BE: /* fall through */
		word &= ~(AC97C_CMR_CEM_LITTLE);
		break;
	default:
		word = ac97c_readl(chip, OCA);
		word &= ~(AC97C_CH_MASK(PCM_LEFT) | AC97C_CH_MASK(PCM_RIGHT));
		ac97c_writel(chip, OCA, word);
		return -EINVAL;
	}

	/* Enable underrun interrupt on channel A */
	word |= AC97C_CSR_UNRUN;

	ac97c_writel(chip, CAMR, word);

	/* Enable channel A event interrupt */
	word = ac97c_readl(chip, IMR);
	word |= AC97C_SR_CAEVT;
	ac97c_writel(chip, IER, word);

	/* set variable rate if needed */
	if (runtime->rate != 48000) {
		word = ac97c_readl(chip, MR);
		word |= AC97C_MR_VRA;
		ac97c_writel(chip, MR, word);
	} else {
		word = ac97c_readl(chip, MR);
		word &= ~(AC97C_MR_VRA);
		ac97c_writel(chip, MR, word);
	}

	retval = snd_ac97_set_rate(chip->ac97, AC97_PCM_FRONT_DAC_RATE,
			runtime->rate);
	if (retval)
		dev_dbg(&chip->pdev->dev, "could not set rate %d Hz\n",
				runtime->rate);

	if (!test_bit(DMA_TX_READY, &chip->flags))
		retval = atmel_ac97c_prepare_dma(chip, substream,
				DMA_TO_DEVICE);

	return retval;
}

static int atmel_ac97c_capture_prepare(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;
	unsigned long word = ac97c_readl(chip, ICA);
	int retval;

	word &= ~(AC97C_CH_MASK(PCM_LEFT) | AC97C_CH_MASK(PCM_RIGHT));

	/* assign channels to AC97C channel A */
	switch (runtime->channels) {
	case 1:
		word |= AC97C_CH_ASSIGN(PCM_LEFT, A);
		break;
	case 2:
		word |= AC97C_CH_ASSIGN(PCM_LEFT, A)
			| AC97C_CH_ASSIGN(PCM_RIGHT, A);
		break;
	default:
		/* TODO: support more than two channels */
		return -EINVAL;
	}
	ac97c_writel(chip, ICA, word);

	/* configure sample format and size */
	word = AC97C_CMR_DMAEN | AC97C_CMR_SIZE_16;

	switch (runtime->format) {
	case SNDRV_PCM_FORMAT_S16_LE:
		word |= AC97C_CMR_CEM_LITTLE;
		break;
	case SNDRV_PCM_FORMAT_S16_BE: /* fall through */
		word &= ~(AC97C_CMR_CEM_LITTLE);
		break;
	default:
		word = ac97c_readl(chip, ICA);
		word &= ~(AC97C_CH_MASK(PCM_LEFT) | AC97C_CH_MASK(PCM_RIGHT));
		ac97c_writel(chip, ICA, word);
		return -EINVAL;
	}

	/* Enable overrun interrupt on channel A */
	word |= AC97C_CSR_OVRUN;

	ac97c_writel(chip, CAMR, word);

	/* Enable channel A event interrupt */
	word = ac97c_readl(chip, IMR);
	word |= AC97C_SR_CAEVT;
	ac97c_writel(chip, IER, word);

	/* set variable rate if needed */
	if (runtime->rate != 48000) {
		word = ac97c_readl(chip, MR);
		word |= AC97C_MR_VRA;
		ac97c_writel(chip, MR, word);
	} else {
		word = ac97c_readl(chip, MR);
		word &= ~(AC97C_MR_VRA);
		ac97c_writel(chip, MR, word);
	}

	retval = snd_ac97_set_rate(chip->ac97, AC97_PCM_LR_ADC_RATE,
			runtime->rate);
	if (retval)
		dev_dbg(&chip->pdev->dev, "could not set rate %d Hz\n",
				runtime->rate);

	if (!test_bit(DMA_RX_READY, &chip->flags))
		retval = atmel_ac97c_prepare_dma(chip, substream,
				DMA_FROM_DEVICE);

	return retval;
}

static int
atmel_ac97c_playback_trigger(struct snd_pcm_substream *substream, int cmd)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	unsigned long camr;
	int retval = 0;

	camr = ac97c_readl(chip, CAMR);

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: /* fall through */
	case SNDRV_PCM_TRIGGER_RESUME: /* fall through */
	case SNDRV_PCM_TRIGGER_START:
		retval = dw_dma_cyclic_start(chip->dma.tx_chan);
		if (retval)
			goto out;
		camr |= AC97C_CMR_CENA;
		break;
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: /* fall through */
	case SNDRV_PCM_TRIGGER_SUSPEND: /* fall through */
	case SNDRV_PCM_TRIGGER_STOP:
		dw_dma_cyclic_stop(chip->dma.tx_chan);
		if (chip->opened <= 1)
			camr &= ~AC97C_CMR_CENA;
		break;
	default:
		retval = -EINVAL;
		goto out;
	}

	ac97c_writel(chip, CAMR, camr);
out:
	return retval;
}

static int
atmel_ac97c_capture_trigger(struct snd_pcm_substream *substream, int cmd)
{
	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
	unsigned long camr;
	int retval = 0;

	camr = ac97c_readl(chip, CAMR);

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: /* fall through */
	case SNDRV_PCM_TRIGGER_RESUME: /* fall through */
	case SNDRV_PCM_TRIGGER_START:
		retval = dw_dma_cyclic_start(chip->dma.rx_chan);
		if (retval)
			goto out;
		camr |= AC97C_CMR_CENA;
		break;
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: /* fall through */
	case SNDRV_PCM_TRIGGER_SUSPEND: /* fall through */
	case SNDRV_PCM_TRIGGER_STOP:
		dw_dma_cyclic_stop(chip->dma.rx_chan);
		if (chip->opened <= 1)
			camr &= ~AC97C_CMR_CENA;
		break;
	default:
		retval = -EINVAL;
		break;
	}

	ac97c_writel(chip, CAMR, camr);
out:
	return retval;
}

static snd_pcm_uframes_t
atmel_ac97c_playback_pointer(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c	*chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime	*runtime = substream->runtime;
	snd_pcm_uframes_t	frames;
	unsigned long		bytes;

	bytes = dw_dma_get_src_addr(chip->dma.tx_chan);
	bytes -= runtime->dma_addr;

	frames = bytes_to_frames(runtime, bytes);
	if (frames >= runtime->buffer_size)
		frames -= runtime->buffer_size;
	return frames;
}

static snd_pcm_uframes_t
atmel_ac97c_capture_pointer(struct snd_pcm_substream *substream)
{
	struct atmel_ac97c	*chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime	*runtime = substream->runtime;
	snd_pcm_uframes_t	frames;
	unsigned long		bytes;

	bytes = dw_dma_get_dst_addr(chip->dma.rx_chan);
	bytes -= runtime->dma_addr;

	frames = bytes_to_frames(runtime, bytes);
	if (frames >= runtime->buffer_size)
		frames -= runtime->buffer_size;
	return frames;
}

static struct snd_pcm_ops atmel_ac97_playback_ops = {
	.open		= atmel_ac97c_playback_open,
	.close		= atmel_ac97c_playback_close,
	.ioctl		= snd_pcm_lib_ioctl,
	.hw_params	= atmel_ac97c_playback_hw_params,
	.hw_free	= atmel_ac97c_playback_hw_free,
	.prepare	= atmel_ac97c_playback_prepare,
	.trigger	= atmel_ac97c_playback_trigger,
	.pointer	= atmel_ac97c_playback_pointer,
};

static struct snd_pcm_ops atmel_ac97_capture_ops = {
	.open		= atmel_ac97c_capture_open,
	.close		= atmel_ac97c_capture_close,
	.ioctl		= snd_pcm_lib_ioctl,
	.hw_params	= atmel_ac97c_capture_hw_params,
	.hw_free	= atmel_ac97c_capture_hw_free,
	.prepare	= atmel_ac97c_capture_prepare,
	.trigger	= atmel_ac97c_capture_trigger,
	.pointer	= atmel_ac97c_capture_pointer,
};

static irqreturn_t atmel_ac97c_interrupt(int irq, void *dev)
{
	struct atmel_ac97c	*chip  = (struct atmel_ac97c *)dev;
	irqreturn_t		retval = IRQ_NONE;
	u32			sr     = ac97c_readl(chip, SR);
	u32			casr   = ac97c_readl(chip, CASR);
	u32			cosr   = ac97c_readl(chip, COSR);

	if (sr & AC97C_SR_CAEVT) {
		dev_info(&chip->pdev->dev, "channel A event%s%s%s%s%s%s\n",
				casr & AC97C_CSR_OVRUN   ? " OVRUN"   : "",
				casr & AC97C_CSR_RXRDY   ? " RXRDY"   : "",
				casr & AC97C_CSR_UNRUN   ? " UNRUN"   : "",
				casr & AC97C_CSR_TXEMPTY ? " TXEMPTY" : "",
				casr & AC97C_CSR_TXRDY   ? " TXRDY"   : "",
				!casr                    ? " NONE"    : "");
		retval = IRQ_HANDLED;
	}

	if (sr & AC97C_SR_COEVT) {
		dev_info(&chip->pdev->dev, "codec channel event%s%s%s%s%s\n",
				cosr & AC97C_CSR_OVRUN   ? " OVRUN"   : "",
				cosr & AC97C_CSR_RXRDY   ? " RXRDY"   : "",
				cosr & AC97C_CSR_TXEMPTY ? " TXEMPTY" : "",
				cosr & AC97C_CSR_TXRDY   ? " TXRDY"   : "",
				!cosr                    ? " NONE"    : "");
		retval = IRQ_HANDLED;
	}

	if (retval == IRQ_NONE) {
		dev_err(&chip->pdev->dev, "spurious interrupt sr 0x%08x "
				"casr 0x%08x cosr 0x%08x\n", sr, casr, cosr);
	}

	return retval;
}

static int __devinit atmel_ac97c_pcm_new(struct atmel_ac97c *chip)
{
	struct snd_pcm		*pcm;
	struct snd_pcm_hardware	hw = atmel_ac97c_hw;
	int			capture, playback, retval;

	capture = test_bit(DMA_RX_CHAN_PRESENT, &chip->flags);
	playback = test_bit(DMA_TX_CHAN_PRESENT, &chip->flags);

	retval = snd_pcm_new(chip->card, chip->card->shortname,
			chip->pdev->id, playback, capture, &pcm);
	if (retval)
		return retval;

	if (capture)
		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE,
				&atmel_ac97_capture_ops);
	if (playback)
		snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
				&atmel_ac97_playback_ops);

	retval = snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
			&chip->pdev->dev, hw.periods_min * hw.period_bytes_min,
			hw.buffer_bytes_max);
	if (retval)
		return retval;

	pcm->private_data = chip;
	pcm->info_flags = 0;
	strcpy(pcm->name, chip->card->shortname);
	chip->pcm = pcm;

	return 0;
}

static int atmel_ac97c_mixer_new(struct atmel_ac97c *chip)
{
	struct snd_ac97_template template;
	memset(&template, 0, sizeof(template));
	template.private_data = chip;
	return snd_ac97_mixer(chip->ac97_bus, &template, &chip->ac97);
}

static void atmel_ac97c_write(struct snd_ac97 *ac97, unsigned short reg,
		unsigned short val)
{
	struct atmel_ac97c *chip = get_chip(ac97);
	unsigned long word;
	int timeout = 40;

	word = (reg & 0x7f) << 16 | val;

	do {
		if (ac97c_readl(chip, COSR) & AC97C_CSR_TXRDY) {
			ac97c_writel(chip, COTHR, word);
			return;
		}
		udelay(1);
	} while (--timeout);

	dev_dbg(&chip->pdev->dev, "codec write timeout\n");
}

static unsigned short atmel_ac97c_read(struct snd_ac97 *ac97,
		unsigned short reg)
{
	struct atmel_ac97c *chip = get_chip(ac97);
	unsigned long word;
	int timeout = 40;
	int write = 10;

	word = (0x80 | (reg & 0x7f)) << 16;

	if ((ac97c_readl(chip, COSR) & AC97C_CSR_RXRDY) != 0)
		ac97c_readl(chip, CORHR);

retry_write:
	timeout = 40;

	do {
		if ((ac97c_readl(chip, COSR) & AC97C_CSR_TXRDY) != 0) {
			ac97c_writel(chip, COTHR, word);
			goto read_reg;
		}
		udelay(10);
	} while (--timeout);

	if (!--write)
		goto timed_out;
	goto retry_write;

read_reg:
	do {
		if ((ac97c_readl(chip, COSR) & AC97C_CSR_RXRDY) != 0) {
			unsigned short val = ac97c_readl(chip, CORHR);
			return val;
		}
		udelay(10);
	} while (--timeout);

	if (!--write)
		goto timed_out;
	goto retry_write;

timed_out:
	dev_dbg(&chip->pdev->dev, "codec read timeout\n");
	return 0xffff;
}

static bool filter(struct dma_chan *chan, void *slave)
{
	struct dw_dma_slave *dws = slave;

	if (dws->dma_dev == chan->device->dev) {
		chan->private = dws;
		return true;
	} else
		return false;
}

static void atmel_ac97c_reset(struct atmel_ac97c *chip)
{
	ac97c_writel(chip, MR,   0);
	ac97c_writel(chip, MR,   AC97C_MR_ENA);
	ac97c_writel(chip, CAMR, 0);
	ac97c_writel(chip, COMR, 0);

	if (gpio_is_valid(chip->reset_pin)) {
		gpio_set_value(chip->reset_pin, 0);
		/* AC97 v2.2 specifications says minimum 1 us. */
		udelay(2);
		gpio_set_value(chip->reset_pin, 1);
	}
}

static int __devinit atmel_ac97c_probe(struct platform_device *pdev)
{
	struct snd_card			*card;
	struct atmel_ac97c		*chip;
	struct resource			*regs;
	struct ac97c_platform_data	*pdata;
	struct clk			*pclk;
	static struct snd_ac97_bus_ops	ops = {
		.write	= atmel_ac97c_write,
		.read	= atmel_ac97c_read,
	};
	int				retval;
	int				irq;

	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!regs) {
		dev_dbg(&pdev->dev, "no memory resource\n");
		return -ENXIO;
	}

	pdata = pdev->dev.platform_data;
	if (!pdata) {
		dev_dbg(&pdev->dev, "no platform data\n");
		return -ENXIO;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		dev_dbg(&pdev->dev, "could not get irq\n");
		return -ENXIO;
	}

	pclk = clk_get(&pdev->dev, "pclk");
	if (IS_ERR(pclk)) {
		dev_dbg(&pdev->dev, "no peripheral clock\n");
		return PTR_ERR(pclk);
	}
	clk_enable(pclk);

	retval = snd_card_create(SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1,
			THIS_MODULE, sizeof(struct atmel_ac97c), &card);
	if (retval) {
		dev_dbg(&pdev->dev, "could not create sound card device\n");
		goto err_snd_card_new;
	}

	chip = get_chip(card);

	retval = request_irq(irq, atmel_ac97c_interrupt, 0, "AC97C", chip);
	if (retval) {
		dev_dbg(&pdev->dev, "unable to request irq %d\n", irq);
		goto err_request_irq;
	}
	chip->irq = irq;

	spin_lock_init(&chip->lock);

	strcpy(card->driver, "Atmel AC97C");
	strcpy(card->shortname, "Atmel AC97C");
	sprintf(card->longname, "Atmel AC97 controller");

	chip->card = card;
	chip->pclk = pclk;
	chip->pdev = pdev;
	chip->regs = ioremap(regs->start, regs->end - regs->start + 1);

	if (!chip->regs) {
		dev_dbg(&pdev->dev, "could not remap register memory\n");
		goto err_ioremap;
	}

	if (gpio_is_valid(pdata->reset_pin)) {
		if (gpio_request(pdata->reset_pin, "reset_pin")) {
			dev_dbg(&pdev->dev, "reset pin not available\n");
			chip->reset_pin = -ENODEV;
		} else {
			gpio_direction_output(pdata->reset_pin, 1);
			chip->reset_pin = pdata->reset_pin;
		}
	}

	snd_card_set_dev(card, &pdev->dev);

	atmel_ac97c_reset(chip);

	/* Enable overrun interrupt from codec channel */
	ac97c_writel(chip, COMR, AC97C_CSR_OVRUN);
	ac97c_writel(chip, IER, ac97c_readl(chip, IMR) | AC97C_SR_COEVT);

	retval = snd_ac97_bus(card, 0, &ops, chip, &chip->ac97_bus);
	if (retval) {
		dev_dbg(&pdev->dev, "could not register on ac97 bus\n");
		goto err_ac97_bus;
	}

	retval = atmel_ac97c_mixer_new(chip);
	if (retval) {
		dev_dbg(&pdev->dev, "could not register ac97 mixer\n");
		goto err_ac97_bus;
	}

	if (pdata->rx_dws.dma_dev) {
		struct dw_dma_slave *dws = &pdata->rx_dws;
		dma_cap_mask_t mask;

		dws->rx_reg = regs->start + AC97C_CARHR + 2;

		dma_cap_zero(mask);
		dma_cap_set(DMA_SLAVE, mask);

		chip->dma.rx_chan = dma_request_channel(mask, filter, dws);

		dev_info(&chip->pdev->dev, "using %s for DMA RX\n",
				dev_name(&chip->dma.rx_chan->dev->device));
		set_bit(DMA_RX_CHAN_PRESENT, &chip->flags);
	}

	if (pdata->tx_dws.dma_dev) {
		struct dw_dma_slave *dws = &pdata->tx_dws;
		dma_cap_mask_t mask;

		dws->tx_reg = regs->start + AC97C_CATHR + 2;

		dma_cap_zero(mask);
		dma_cap_set(DMA_SLAVE, mask);

		chip->dma.tx_chan = dma_request_channel(mask, filter, dws);

		dev_info(&chip->pdev->dev, "using %s for DMA TX\n",
				dev_name(&chip->dma.tx_chan->dev->device));
		set_bit(DMA_TX_CHAN_PRESENT, &chip->flags);
	}

	if (!test_bit(DMA_RX_CHAN_PRESENT, &chip->flags) &&
			!test_bit(DMA_TX_CHAN_PRESENT, &chip->flags)) {
		dev_dbg(&pdev->dev, "DMA not available\n");
		retval = -ENODEV;
		goto err_dma;
	}

	retval = atmel_ac97c_pcm_new(chip);
	if (retval) {
		dev_dbg(&pdev->dev, "could not register ac97 pcm device\n");
		goto err_dma;
	}

	retval = snd_card_register(card);
	if (retval) {
		dev_dbg(&pdev->dev, "could not register sound card\n");
		goto err_dma;
	}

	platform_set_drvdata(pdev, card);

	dev_info(&pdev->dev, "Atmel AC97 controller at 0x%p\n",
			chip->regs);

	return 0;

err_dma:
	if (test_bit(DMA_RX_CHAN_PRESENT, &chip->flags))
		dma_release_channel(chip->dma.rx_chan);
	if (test_bit(DMA_TX_CHAN_PRESENT, &chip->flags))
		dma_release_channel(chip->dma.tx_chan);
	clear_bit(DMA_RX_CHAN_PRESENT, &chip->flags);
	clear_bit(DMA_TX_CHAN_PRESENT, &chip->flags);
	chip->dma.rx_chan = NULL;
	chip->dma.tx_chan = NULL;
err_ac97_bus:
	snd_card_set_dev(card, NULL);

	if (gpio_is_valid(chip->reset_pin))
		gpio_free(chip->reset_pin);

	iounmap(chip->regs);
err_ioremap:
	free_irq(irq, chip);
err_request_irq:
	snd_card_free(card);
err_snd_card_new:
	clk_disable(pclk);
	clk_put(pclk);
	return retval;
}

#ifdef CONFIG_PM
static int atmel_ac97c_suspend(struct platform_device *pdev, pm_message_t msg)
{
	struct snd_card *card = platform_get_drvdata(pdev);
	struct atmel_ac97c *chip = card->private_data;

	if (test_bit(DMA_RX_READY, &chip->flags))
		dw_dma_cyclic_stop(chip->dma.rx_chan);
	if (test_bit(DMA_TX_READY, &chip->flags))
		dw_dma_cyclic_stop(chip->dma.tx_chan);
	clk_disable(chip->pclk);

	return 0;
}

static int atmel_ac97c_resume(struct platform_device *pdev)
{
	struct snd_card *card = platform_get_drvdata(pdev);
	struct atmel_ac97c *chip = card->private_data;

	clk_enable(chip->pclk);
	if (test_bit(DMA_RX_READY, &chip->flags))
		dw_dma_cyclic_start(chip->dma.rx_chan);
	if (test_bit(DMA_TX_READY, &chip->flags))
		dw_dma_cyclic_start(chip->dma.tx_chan);

	return 0;
}
#else
#define atmel_ac97c_suspend NULL
#define atmel_ac97c_resume NULL
#endif

static int __devexit atmel_ac97c_remove(struct platform_device *pdev)
{
	struct snd_card *card = platform_get_drvdata(pdev);
	struct atmel_ac97c *chip = get_chip(card);

	if (gpio_is_valid(chip->reset_pin))
		gpio_free(chip->reset_pin);

	ac97c_writel(chip, CAMR, 0);
	ac97c_writel(chip, COMR, 0);
	ac97c_writel(chip, MR,   0);

	clk_disable(chip->pclk);
	clk_put(chip->pclk);
	iounmap(chip->regs);
	free_irq(chip->irq, chip);

	if (test_bit(DMA_RX_CHAN_PRESENT, &chip->flags))
		dma_release_channel(chip->dma.rx_chan);
	if (test_bit(DMA_TX_CHAN_PRESENT, &chip->flags))
		dma_release_channel(chip->dma.tx_chan);
	clear_bit(DMA_RX_CHAN_PRESENT, &chip->flags);
	clear_bit(DMA_TX_CHAN_PRESENT, &chip->flags);
	chip->dma.rx_chan = NULL;
	chip->dma.tx_chan = NULL;

	snd_card_set_dev(card, NULL);
	snd_card_free(card);

	platform_set_drvdata(pdev, NULL);

	return 0;
}

static struct platform_driver atmel_ac97c_driver = {
	.remove		= __devexit_p(atmel_ac97c_remove),
	.driver		= {
		.name	= "atmel_ac97c",
	},
	.suspend	= atmel_ac97c_suspend,
	.resume		= atmel_ac97c_resume,
};

static int __init atmel_ac97c_init(void)
{
	return platform_driver_probe(&atmel_ac97c_driver,
			atmel_ac97c_probe);
}
module_init(atmel_ac97c_init);

static void __exit atmel_ac97c_exit(void)
{
	platform_driver_unregister(&atmel_ac97c_driver);
}
module_exit(atmel_ac97c_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Driver for Atmel AC97 controller");
MODULE_AUTHOR("Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>");