/*

   * 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/atmel_pdc.h>

  #include <linux/gpio/consumer.h>

  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/mutex.h>

  #include <linux/types.h>

  #include <linux/io.h>

  #include <linux/of.h>

  #include <linux/of_device.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/memalloc.h>

  #include "ac97c.h"

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

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

  
  	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;

  	int				playback_period, capture_period;

  	/* Serialize access to opened variable */
  	spinlock_t			lock;
  	void __iomem			*regs;

  	int				irq;

  	int				opened;

  	struct gpio_desc		*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)

  static const 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 = pcm_format_to_bits(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 = pcm_format_to_bits(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;

  	/* 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;

  
  	/* 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_prepare(struct snd_pcm_substream *substream)
  {
  	struct atmel_ac97c *chip = snd_pcm_substream_chip(substream);
  	struct snd_pcm_runtime *runtime = substream->runtime;

  	int block_size = frames_to_bytes(runtime, runtime->period_size);

  	unsigned long word = ac97c_readl(chip, OCA);

  	int retval;

  	chip->playback_period = 0;

  	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_readl(chip, CAMR);
  	if (chip->opened <= 1)
  		word = AC97C_CMR_DMAEN | AC97C_CMR_SIZE_16;
  	else
  		word |= AC97C_CMR_DMAEN | AC97C_CMR_SIZE_16;

  
  	switch (runtime->format) {
  	case SNDRV_PCM_FORMAT_S16_LE:

  		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
  ",
  				runtime->rate);

  	/* Initialize and start the PDC */
  	writel(runtime->dma_addr, chip->regs + ATMEL_PDC_TPR);
  	writel(block_size / 2, chip->regs + ATMEL_PDC_TCR);
  	writel(runtime->dma_addr + block_size, chip->regs + ATMEL_PDC_TNPR);
  	writel(block_size / 2, chip->regs + ATMEL_PDC_TNCR);

  
  	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;

  	int block_size = frames_to_bytes(runtime, runtime->period_size);

  	unsigned long word = ac97c_readl(chip, ICA);

  	int retval;

  	chip->capture_period = 0;

  	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_readl(chip, CAMR);
  	if (chip->opened <= 1)
  		word = AC97C_CMR_DMAEN | AC97C_CMR_SIZE_16;
  	else
  		word |= AC97C_CMR_DMAEN | AC97C_CMR_SIZE_16;

  
  	switch (runtime->format) {
  	case SNDRV_PCM_FORMAT_S16_LE:

  		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
  ",
  				runtime->rate);

  	/* Initialize and start the PDC */
  	writel(runtime->dma_addr, chip->regs + ATMEL_PDC_RPR);
  	writel(block_size / 2, chip->regs + ATMEL_PDC_RCR);
  	writel(runtime->dma_addr + block_size, chip->regs + ATMEL_PDC_RNPR);
  	writel(block_size / 2, chip->regs + ATMEL_PDC_RNCR);

  
  	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, ptcr = 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:

  		ptcr = ATMEL_PDC_TXTEN;

  		camr |= AC97C_CMR_CENA | AC97C_CSR_ENDTX;

  		break;
  	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: /* fall through */
  	case SNDRV_PCM_TRIGGER_SUSPEND: /* fall through */
  	case SNDRV_PCM_TRIGGER_STOP:

  		ptcr |= ATMEL_PDC_TXTDIS;

  		if (chip->opened <= 1)
  			camr &= ~AC97C_CMR_CENA;
  		break;
  	default:

  		return -EINVAL;

  	}
  
  	ac97c_writel(chip, CAMR, camr);

  	writel(ptcr, chip->regs + ATMEL_PDC_PTCR);
  	return 0;

  }
  
  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, ptcr = 0;

  
  	camr = ac97c_readl(chip, CAMR);

  	ptcr = readl(chip->regs + ATMEL_PDC_PTSR);

  
  	switch (cmd) {
  	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: /* fall through */
  	case SNDRV_PCM_TRIGGER_RESUME: /* fall through */
  	case SNDRV_PCM_TRIGGER_START:

  		ptcr = ATMEL_PDC_RXTEN;

  		camr |= AC97C_CMR_CENA | AC97C_CSR_ENDRX;

  		break;
  	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: /* fall through */
  	case SNDRV_PCM_TRIGGER_SUSPEND: /* fall through */
  	case SNDRV_PCM_TRIGGER_STOP:

  		ptcr |= ATMEL_PDC_RXTDIS;

  		if (chip->opened <= 1)
  			camr &= ~AC97C_CMR_CENA;
  		break;
  	default:

  		return -EINVAL;

  	}
  
  	ac97c_writel(chip, CAMR, camr);

  	writel(ptcr, chip->regs + ATMEL_PDC_PTCR);
  	return 0;

  }
  
  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 = readl(chip->regs + ATMEL_PDC_TPR);

  	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 = readl(chip->regs + ATMEL_PDC_RPR);

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

  static const 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	= snd_pcm_lib_free_pages,

  	.prepare	= atmel_ac97c_playback_prepare,
  	.trigger	= atmel_ac97c_playback_trigger,
  	.pointer	= atmel_ac97c_playback_pointer,
  };

  static const 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	= snd_pcm_lib_free_pages,

  	.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);

  	u32			camr   = ac97c_readl(chip, CAMR);

  
  	if (sr & AC97C_SR_CAEVT) {

  		struct snd_pcm_runtime *runtime;
  		int offset, next_period, block_size;

  		dev_dbg(&chip->pdev->dev, "channel A event%s%s%s%s%s%s
  ",

  				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"    : "");

  		if ((casr & camr) & AC97C_CSR_ENDTX) {
  			runtime = chip->playback_substream->runtime;
  			block_size = frames_to_bytes(runtime, runtime->period_size);
  			chip->playback_period++;
  
  			if (chip->playback_period == runtime->periods)
  				chip->playback_period = 0;
  			next_period = chip->playback_period + 1;
  			if (next_period == runtime->periods)
  				next_period = 0;
  
  			offset = block_size * next_period;
  
  			writel(runtime->dma_addr + offset, chip->regs + ATMEL_PDC_TNPR);
  			writel(block_size / 2, chip->regs + ATMEL_PDC_TNCR);
  
  			snd_pcm_period_elapsed(chip->playback_substream);
  		}
  		if ((casr & camr) & AC97C_CSR_ENDRX) {
  			runtime = chip->capture_substream->runtime;
  			block_size = frames_to_bytes(runtime, runtime->period_size);
  			chip->capture_period++;
  
  			if (chip->capture_period == runtime->periods)
  				chip->capture_period = 0;
  			next_period = chip->capture_period + 1;
  			if (next_period == runtime->periods)
  				next_period = 0;
  
  			offset = block_size * next_period;
  
  			writel(runtime->dma_addr + offset, chip->regs + ATMEL_PDC_RNPR);
  			writel(block_size / 2, chip->regs + ATMEL_PDC_RNCR);
  			snd_pcm_period_elapsed(chip->capture_substream);

  		}

  		retval = IRQ_HANDLED;
  	}
  
  	if (sr & AC97C_SR_COEVT) {
  		dev_info(&chip->pdev->dev, "codec channel event%s%s%s%s%s
  ",
  				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
  ", sr, casr, cosr);
  	}
  
  	return retval;
  }

  static const struct ac97_pcm at91_ac97_pcm_defs[] = {

  	/* Playback */
  	{
  		.exclusive = 1,
  		.r = { {
  			.slots = ((1 << AC97_SLOT_PCM_LEFT)
  				  | (1 << AC97_SLOT_PCM_RIGHT)),
  		} },
  	},
  	/* PCM in */
  	{
  		.stream = 1,
  		.exclusive = 1,
  		.r = { {
  			.slots = ((1 << AC97_SLOT_PCM_LEFT)
  					| (1 << AC97_SLOT_PCM_RIGHT)),
  		} }
  	},
  	/* Mic in */
  	{
  		.stream = 1,
  		.exclusive = 1,
  		.r = { {
  			.slots = (1<<AC97_SLOT_MIC),
  		} }
  	},
  };

  static int atmel_ac97c_pcm_new(struct atmel_ac97c *chip)

  {
  	struct snd_pcm		*pcm;
  	struct snd_pcm_hardware	hw = atmel_ac97c_hw;

  	int			retval;

  	retval = snd_ac97_pcm_assign(chip->ac97_bus,
  				     ARRAY_SIZE(at91_ac97_pcm_defs),
  				     at91_ac97_pcm_defs);
  	if (retval)
  		return retval;

  	retval = snd_pcm_new(chip->card, chip->card->shortname, 0, 1, 1, &pcm);

  	if (retval)
  		return retval;

  	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &atmel_ac97_capture_ops);
  	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
  ");
  }
  
  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
  ");
  	return 0xffff;
  }

  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 (!IS_ERR(chip->reset_pin)) {
  		gpiod_set_value(chip->reset_pin, 0);

  		/* AC97 v2.2 specifications says minimum 1 us. */

  		udelay(2);

  		gpiod_set_value(chip->reset_pin, 1);

  	} else {
  		ac97c_writel(chip, MR, AC97C_MR_WRST | AC97C_MR_ENA);
  		udelay(2);
  		ac97c_writel(chip, MR, AC97C_MR_ENA);

  	}

  }

  static const struct of_device_id atmel_ac97c_dt_ids[] = {
  	{ .compatible = "atmel,at91sam9263-ac97c", },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, atmel_ac97c_dt_ids);

  static int atmel_ac97c_probe(struct platform_device *pdev)

  {

  	struct device			*dev = &pdev->dev;

  	struct snd_card			*card;
  	struct atmel_ac97c		*chip;
  	struct resource			*regs;

  	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
  ");
  		return -ENXIO;
  	}

  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0) {

  		dev_dbg(&pdev->dev, "could not get irq: %d
  ", irq);
  		return irq;

  	}

  	pclk = clk_get(&pdev->dev, "ac97_clk");

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

  	retval = clk_prepare_enable(pclk);
  	if (retval)

  		goto err_prepare_enable;

  	retval = snd_card_new(&pdev->dev, 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
  ");
  		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
  ", 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, resource_size(regs));

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

  		retval = -ENOMEM;

  		goto err_ioremap;
  	}

  	chip->reset_pin = devm_gpiod_get_index(dev, "ac97", 2, GPIOD_OUT_HIGH);
  	if (IS_ERR(chip->reset_pin))
  		dev_dbg(dev, "reset pin not available
  ");

  	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
  ");
  		goto err_ac97_bus;
  	}

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

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

  		goto err_ac97_bus;

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

  		goto err_ac97_bus;

  	}
  
  	platform_set_drvdata(pdev, card);

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

  
  	return 0;

  err_ac97_bus:

  	iounmap(chip->regs);
  err_ioremap:

  	free_irq(irq, chip);
  err_request_irq:

  	snd_card_free(card);
  err_snd_card_new:

  	clk_disable_unprepare(pclk);

  err_prepare_enable:

  	clk_put(pclk);
  	return retval;
  }

  #ifdef CONFIG_PM_SLEEP

  static int atmel_ac97c_suspend(struct device *pdev)

  {

  	struct snd_card *card = dev_get_drvdata(pdev);

  	struct atmel_ac97c *chip = card->private_data;

  	clk_disable_unprepare(chip->pclk);

  	return 0;
  }

  static int atmel_ac97c_resume(struct device *pdev)

  {

  	struct snd_card *card = dev_get_drvdata(pdev);

  	struct atmel_ac97c *chip = card->private_data;

  	int ret = clk_prepare_enable(chip->pclk);

  	return ret;

  }

  
  static SIMPLE_DEV_PM_OPS(atmel_ac97c_pm, atmel_ac97c_suspend, atmel_ac97c_resume);
  #define ATMEL_AC97C_PM_OPS	&atmel_ac97c_pm

  #else

  #define ATMEL_AC97C_PM_OPS	NULL

  #endif

  static int atmel_ac97c_remove(struct platform_device *pdev)

  {
  	struct snd_card *card = platform_get_drvdata(pdev);
  	struct atmel_ac97c *chip = get_chip(card);

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

  	clk_disable_unprepare(chip->pclk);

  	clk_put(chip->pclk);
  	iounmap(chip->regs);

  	free_irq(chip->irq, chip);

  	snd_card_free(card);

  	return 0;
  }
  
  static struct platform_driver atmel_ac97c_driver = {

  	.probe		= atmel_ac97c_probe,

  	.remove		= atmel_ac97c_remove,

  	.driver		= {
  		.name	= "atmel_ac97c",

  		.pm	= ATMEL_AC97C_PM_OPS,

  		.of_match_table = atmel_ac97c_dt_ids,

  	},

  };

  module_platform_driver(atmel_ac97c_driver);

  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Driver for Atmel AC97 controller");

  MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");