sound/soc/cirrus/ep93xx-ac97.c - arm/linux-arm64-legacy - Git at Google

 /*
  * ASoC driver for Cirrus Logic EP93xx AC97 controller.
  *
  * Copyright (c) 2010 Mika Westerberg
  *
  * Based on s3c-ac97 ASoC driver by Jaswinder Singh.
  *
  * 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/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>

 #include <sound/core.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/ac97_codec.h>
 #include <sound/soc.h>

 #include <linux/platform_data/dma-ep93xx.h>

 #include "ep93xx-pcm.h"

 /*
  * Per channel (1-4) registers.
  */
 #define AC97CH(n)		(((n) - 1) * 0x20)

 #define AC97DR(n)		(AC97CH(n) + 0x0000)

 #define AC97RXCR(n)		(AC97CH(n) + 0x0004)
 #define AC97RXCR_REN		BIT(0)
 #define AC97RXCR_RX3		BIT(3)
 #define AC97RXCR_RX4		BIT(4)
 #define AC97RXCR_CM		BIT(15)

 #define AC97TXCR(n)		(AC97CH(n) + 0x0008)
 #define AC97TXCR_TEN		BIT(0)
 #define AC97TXCR_TX3		BIT(3)
 #define AC97TXCR_TX4		BIT(4)
 #define AC97TXCR_CM		BIT(15)

 #define AC97SR(n)		(AC97CH(n) + 0x000c)
 #define AC97SR_TXFE		BIT(1)
 #define AC97SR_TXUE		BIT(6)

 #define AC97RISR(n)		(AC97CH(n) + 0x0010)
 #define AC97ISR(n)		(AC97CH(n) + 0x0014)
 #define AC97IE(n)		(AC97CH(n) + 0x0018)

 /*
  * Global AC97 controller registers.
  */
 #define AC97S1DATA		0x0080
 #define AC97S2DATA		0x0084
 #define AC97S12DATA		0x0088

 #define AC97RGIS		0x008c
 #define AC97GIS			0x0090
 #define AC97IM			0x0094
 /*
  * Common bits for RGIS, GIS and IM registers.
  */
 #define AC97_SLOT2RXVALID	BIT(1)
 #define AC97_CODECREADY		BIT(5)
 #define AC97_SLOT2TXCOMPLETE	BIT(6)

 #define AC97EOI			0x0098
 #define AC97EOI_WINT		BIT(0)
 #define AC97EOI_CODECREADY	BIT(1)

 #define AC97GCR			0x009c
 #define AC97GCR_AC97IFE		BIT(0)

 #define AC97RESET		0x00a0
 #define AC97RESET_TIMEDRESET	BIT(0)

 #define AC97SYNC		0x00a4
 #define AC97SYNC_TIMEDSYNC	BIT(0)

 #define AC97_TIMEOUT		msecs_to_jiffies(5)

 /**
  * struct ep93xx_ac97_info - EP93xx AC97 controller info structure
  * @lock: mutex serializing access to the bus (slot 1 & 2 ops)
  * @dev: pointer to the platform device dev structure
  * @regs: mapped AC97 controller registers
  * @done: bus ops wait here for an interrupt
  */
 struct ep93xx_ac97_info {
 	struct mutex		lock;
 	struct device		*dev;
 	void __iomem		*regs;
 	struct completion	done;
 	struct snd_dmaengine_dai_dma_data dma_params_rx;
 	struct snd_dmaengine_dai_dma_data dma_params_tx;
 };

 /* currently ALSA only supports a single AC97 device */
 static struct ep93xx_ac97_info *ep93xx_ac97_info;

 static struct ep93xx_dma_data ep93xx_ac97_pcm_out = {
 	.name		= "ac97-pcm-out",
 	.port		= EP93XX_DMA_AAC1,
 	.direction	= DMA_MEM_TO_DEV,
 };

 static struct ep93xx_dma_data ep93xx_ac97_pcm_in = {
 	.name		= "ac97-pcm-in",
 	.port		= EP93XX_DMA_AAC1,
 	.direction	= DMA_DEV_TO_MEM,
 };

 static inline unsigned ep93xx_ac97_read_reg(struct ep93xx_ac97_info *info,
 					    unsigned reg)
 {
 	return __raw_readl(info->regs + reg);
 }

 static inline void ep93xx_ac97_write_reg(struct ep93xx_ac97_info *info,
 					 unsigned reg, unsigned val)
 {
 	__raw_writel(val, info->regs + reg);
 }

 static unsigned short ep93xx_ac97_read(struct snd_ac97 *ac97,
 				       unsigned short reg)
 {
 	struct ep93xx_ac97_info *info = ep93xx_ac97_info;
 	unsigned short val;

 	mutex_lock(&info->lock);

 	ep93xx_ac97_write_reg(info, AC97S1DATA, reg);
 	ep93xx_ac97_write_reg(info, AC97IM, AC97_SLOT2RXVALID);
 	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT)) {
 		dev_warn(info->dev, "timeout reading register %x\n", reg);
 		mutex_unlock(&info->lock);
 		return -ETIMEDOUT;
 	}
 	val = (unsigned short)ep93xx_ac97_read_reg(info, AC97S2DATA);

 	mutex_unlock(&info->lock);
 	return val;
 }

 static void ep93xx_ac97_write(struct snd_ac97 *ac97,
 			      unsigned short reg,
 			      unsigned short val)
 {
 	struct ep93xx_ac97_info *info = ep93xx_ac97_info;

 	mutex_lock(&info->lock);

 	/*
 	 * Writes to the codec need to be done so that slot 2 is filled in
 	 * before slot 1.
 	 */
 	ep93xx_ac97_write_reg(info, AC97S2DATA, val);
 	ep93xx_ac97_write_reg(info, AC97S1DATA, reg);

 	ep93xx_ac97_write_reg(info, AC97IM, AC97_SLOT2TXCOMPLETE);
 	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT))
 		dev_warn(info->dev, "timeout writing register %x\n", reg);

 	mutex_unlock(&info->lock);
 }

 static void ep93xx_ac97_warm_reset(struct snd_ac97 *ac97)
 {
 	struct ep93xx_ac97_info *info = ep93xx_ac97_info;

 	mutex_lock(&info->lock);

 	/*
 	 * We are assuming that before this functions gets called, the codec
 	 * BIT_CLK is stopped by forcing the codec into powerdown mode. We can
 	 * control the SYNC signal directly via AC97SYNC register. Using
 	 * TIMEDSYNC the controller will keep the SYNC high > 1us.
 	 */
 	ep93xx_ac97_write_reg(info, AC97SYNC, AC97SYNC_TIMEDSYNC);
 	ep93xx_ac97_write_reg(info, AC97IM, AC97_CODECREADY);
 	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT))
 		dev_warn(info->dev, "codec warm reset timeout\n");

 	mutex_unlock(&info->lock);
 }

 static void ep93xx_ac97_cold_reset(struct snd_ac97 *ac97)
 {
 	struct ep93xx_ac97_info *info = ep93xx_ac97_info;

 	mutex_lock(&info->lock);

 	/*
 	 * For doing cold reset, we disable the AC97 controller interface, clear
 	 * WINT and CODECREADY bits, and finally enable the interface again.
 	 */
 	ep93xx_ac97_write_reg(info, AC97GCR, 0);
 	ep93xx_ac97_write_reg(info, AC97EOI, AC97EOI_CODECREADY | AC97EOI_WINT);
 	ep93xx_ac97_write_reg(info, AC97GCR, AC97GCR_AC97IFE);

 	/*
 	 * Now, assert the reset and wait for the codec to become ready.
 	 */
 	ep93xx_ac97_write_reg(info, AC97RESET, AC97RESET_TIMEDRESET);
 	ep93xx_ac97_write_reg(info, AC97IM, AC97_CODECREADY);
 	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT))
 		dev_warn(info->dev, "codec cold reset timeout\n");

 	/*
 	 * Give the codec some time to come fully out from the reset. This way
 	 * we ensure that the subsequent reads/writes will work.
 	 */
 	usleep_range(15000, 20000);

 	mutex_unlock(&info->lock);
 }

 static irqreturn_t ep93xx_ac97_interrupt(int irq, void *dev_id)
 {
 	struct ep93xx_ac97_info *info = dev_id;
 	unsigned status, mask;

 	/*
 	 * Just mask out the interrupt and wake up the waiting thread.
 	 * Interrupts are cleared via reading/writing to slot 1 & 2 registers by
 	 * the waiting thread.
 	 */
 	status = ep93xx_ac97_read_reg(info, AC97GIS);
 	mask = ep93xx_ac97_read_reg(info, AC97IM);
 	mask &= ~status;
 	ep93xx_ac97_write_reg(info, AC97IM, mask);

 	complete(&info->done);
 	return IRQ_HANDLED;
 }

 static struct snd_ac97_bus_ops ep93xx_ac97_ops = {
 	.read		= ep93xx_ac97_read,
 	.write		= ep93xx_ac97_write,
 	.reset		= ep93xx_ac97_cold_reset,
 	.warm_reset	= ep93xx_ac97_warm_reset,
 };

 static int ep93xx_ac97_trigger(struct snd_pcm_substream *substream,
 			       int cmd, struct snd_soc_dai *dai)
 {
 	struct ep93xx_ac97_info *info = snd_soc_dai_get_drvdata(dai);
 	unsigned v = 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) {
 			/*
 			 * Enable compact mode, TX slots 3 & 4, and the TX FIFO
 			 * itself.
 			 */
 			v |= AC97TXCR_CM;
 			v |= AC97TXCR_TX3 | AC97TXCR_TX4;
 			v |= AC97TXCR_TEN;
 			ep93xx_ac97_write_reg(info, AC97TXCR(1), v);
 		} else {
 			/*
 			 * Enable compact mode, RX slots 3 & 4, and the RX FIFO
 			 * itself.
 			 */
 			v |= AC97RXCR_CM;
 			v |= AC97RXCR_RX3 | AC97RXCR_RX4;
 			v |= AC97RXCR_REN;
 			ep93xx_ac97_write_reg(info, AC97RXCR(1), v);
 		}
 		break;

 	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 			/*
 			 * As per Cirrus EP93xx errata described below:
 			 *
 			 * http://www.cirrus.com/en/pubs/errata/ER667E2B.pdf
 			 *
 			 * we will wait for the TX FIFO to be empty before
 			 * clearing the TEN bit.
 			 */
 			unsigned long timeout = jiffies + AC97_TIMEOUT;

 			do {
 				v = ep93xx_ac97_read_reg(info, AC97SR(1));
 				if (time_after(jiffies, timeout)) {
 					dev_warn(info->dev, "TX timeout\n");
 					break;
 				}
 			} while (!(v & (AC97SR_TXFE | AC97SR_TXUE)));

 			/* disable the TX FIFO */
 			ep93xx_ac97_write_reg(info, AC97TXCR(1), 0);
 		} else {
 			/* disable the RX FIFO */
 			ep93xx_ac97_write_reg(info, AC97RXCR(1), 0);
 		}
 		break;

 	default:
 		dev_warn(info->dev, "unknown command %d\n", cmd);
 		return -EINVAL;
 	}

 	return 0;
 }

 static int ep93xx_ac97_dai_probe(struct snd_soc_dai *dai)
 {
 	struct ep93xx_ac97_info *info = snd_soc_dai_get_drvdata(dai);

 	info->dma_params_tx.filter_data = &ep93xx_ac97_pcm_out;
 	info->dma_params_rx.filter_data = &ep93xx_ac97_pcm_in;

 	dai->playback_dma_data = &info->dma_params_tx;
 	dai->capture_dma_data = &info->dma_params_rx;

 	return 0;
 }

 static const struct snd_soc_dai_ops ep93xx_ac97_dai_ops = {
 	.trigger	= ep93xx_ac97_trigger,
 };

 static struct snd_soc_dai_driver ep93xx_ac97_dai = {
 	.name		= "ep93xx-ac97",
 	.id		= 0,
 	.ac97_control	= 1,
 	.probe		= ep93xx_ac97_dai_probe,
 	.playback	= {
 		.stream_name	= "AC97 Playback",
 		.channels_min	= 2,
 		.channels_max	= 2,
 		.rates		= SNDRV_PCM_RATE_8000_48000,
 		.formats	= SNDRV_PCM_FMTBIT_S16_LE,
 	},
 	.capture	= {
 		.stream_name	= "AC97 Capture",
 		.channels_min	= 2,
 		.channels_max	= 2,
 		.rates		= SNDRV_PCM_RATE_8000_48000,
 		.formats	= SNDRV_PCM_FMTBIT_S16_LE,
 	},
 	.ops			= &ep93xx_ac97_dai_ops,
 };

 static const struct snd_soc_component_driver ep93xx_ac97_component = {
 	.name		= "ep93xx-ac97",
 };

 static int ep93xx_ac97_probe(struct platform_device *pdev)
 {
 	struct ep93xx_ac97_info *info;
 	struct resource *res;
 	unsigned int irq;
 	int ret;

 	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return -ENOMEM;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	info->regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(info->regs))
 		return PTR_ERR(info->regs);

 	irq = platform_get_irq(pdev, 0);
 	if (!irq)
 		return -ENODEV;

 	ret = devm_request_irq(&pdev->dev, irq, ep93xx_ac97_interrupt,
 			       IRQF_TRIGGER_HIGH, pdev->name, info);
 	if (ret)
 		goto fail;

 	dev_set_drvdata(&pdev->dev, info);

 	mutex_init(&info->lock);
 	init_completion(&info->done);
 	info->dev = &pdev->dev;

 	ep93xx_ac97_info = info;
 	platform_set_drvdata(pdev, info);

 	ret = snd_soc_set_ac97_ops(&ep93xx_ac97_ops);
 	if (ret)
 		goto fail;

 	ret = snd_soc_register_component(&pdev->dev, &ep93xx_ac97_component,
 					 &ep93xx_ac97_dai, 1);
 	if (ret)
 		goto fail;

 	ret = devm_ep93xx_pcm_platform_register(&pdev->dev);
 	if (ret)
 		goto fail_unregister;

 	return 0;

 fail_unregister:
 	snd_soc_unregister_component(&pdev->dev);
 fail:
 	ep93xx_ac97_info = NULL;
 	snd_soc_set_ac97_ops(NULL);
 	return ret;
 }

 static int ep93xx_ac97_remove(struct platform_device *pdev)
 {
 	struct ep93xx_ac97_info	*info = platform_get_drvdata(pdev);

 	snd_soc_unregister_component(&pdev->dev);

 	/* disable the AC97 controller */
 	ep93xx_ac97_write_reg(info, AC97GCR, 0);

 	ep93xx_ac97_info = NULL;

 	snd_soc_set_ac97_ops(NULL);

 	return 0;
 }

 static struct platform_driver ep93xx_ac97_driver = {
 	.probe	= ep93xx_ac97_probe,
 	.remove	= ep93xx_ac97_remove,
 	.driver = {
 		.name = "ep93xx-ac97",
 		.owner = THIS_MODULE,
 	},
 };

 module_platform_driver(ep93xx_ac97_driver);

 MODULE_DESCRIPTION("EP93xx AC97 ASoC Driver");
 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:ep93xx-ac97");
	/*
	* ASoC driver for Cirrus Logic EP93xx AC97 controller.
	*
	* Copyright (c) 2010 Mika Westerberg
	*
	* Based on s3c-ac97 ASoC driver by Jaswinder Singh.
	*
	* 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/delay.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>

	#include <sound/core.h>
	#include <sound/dmaengine_pcm.h>
	#include <sound/ac97_codec.h>
	#include <sound/soc.h>

	#include <linux/platform_data/dma-ep93xx.h>

	#include "ep93xx-pcm.h"

	/*
	* Per channel (1-4) registers.
	*/
	#define AC97CH(n) (((n) - 1) * 0x20)

	#define AC97DR(n) (AC97CH(n) + 0x0000)

	#define AC97RXCR(n) (AC97CH(n) + 0x0004)
	#define AC97RXCR_REN BIT(0)
	#define AC97RXCR_RX3 BIT(3)
	#define AC97RXCR_RX4 BIT(4)
	#define AC97RXCR_CM BIT(15)

	#define AC97TXCR(n) (AC97CH(n) + 0x0008)
	#define AC97TXCR_TEN BIT(0)
	#define AC97TXCR_TX3 BIT(3)
	#define AC97TXCR_TX4 BIT(4)
	#define AC97TXCR_CM BIT(15)

	#define AC97SR(n) (AC97CH(n) + 0x000c)
	#define AC97SR_TXFE BIT(1)
	#define AC97SR_TXUE BIT(6)

	#define AC97RISR(n) (AC97CH(n) + 0x0010)
	#define AC97ISR(n) (AC97CH(n) + 0x0014)
	#define AC97IE(n) (AC97CH(n) + 0x0018)

	/*
	* Global AC97 controller registers.
	*/
	#define AC97S1DATA 0x0080
	#define AC97S2DATA 0x0084
	#define AC97S12DATA 0x0088

	#define AC97RGIS 0x008c
	#define AC97GIS 0x0090
	#define AC97IM 0x0094
	/*
	* Common bits for RGIS, GIS and IM registers.
	*/
	#define AC97_SLOT2RXVALID BIT(1)
	#define AC97_CODECREADY BIT(5)
	#define AC97_SLOT2TXCOMPLETE BIT(6)

	#define AC97EOI 0x0098
	#define AC97EOI_WINT BIT(0)
	#define AC97EOI_CODECREADY BIT(1)

	#define AC97GCR 0x009c
	#define AC97GCR_AC97IFE BIT(0)

	#define AC97RESET 0x00a0
	#define AC97RESET_TIMEDRESET BIT(0)

	#define AC97SYNC 0x00a4
	#define AC97SYNC_TIMEDSYNC BIT(0)

	#define AC97_TIMEOUT msecs_to_jiffies(5)

	/**
	* struct ep93xx_ac97_info - EP93xx AC97 controller info structure
	* @lock: mutex serializing access to the bus (slot 1 & 2 ops)
	* @dev: pointer to the platform device dev structure
	* @regs: mapped AC97 controller registers
	* @done: bus ops wait here for an interrupt
	*/
	struct ep93xx_ac97_info {
	struct mutex lock;
	struct device *dev;
	void __iomem *regs;
	struct completion done;
	struct snd_dmaengine_dai_dma_data dma_params_rx;
	struct snd_dmaengine_dai_dma_data dma_params_tx;
	};

	/* currently ALSA only supports a single AC97 device */
	static struct ep93xx_ac97_info *ep93xx_ac97_info;

	static struct ep93xx_dma_data ep93xx_ac97_pcm_out = {
	.name = "ac97-pcm-out",
	.port = EP93XX_DMA_AAC1,
	.direction = DMA_MEM_TO_DEV,
	};

	static struct ep93xx_dma_data ep93xx_ac97_pcm_in = {
	.name = "ac97-pcm-in",
	.port = EP93XX_DMA_AAC1,
	.direction = DMA_DEV_TO_MEM,
	};

	static inline unsigned ep93xx_ac97_read_reg(struct ep93xx_ac97_info *info,
	unsigned reg)
	{
	return __raw_readl(info->regs + reg);
	}

	static inline void ep93xx_ac97_write_reg(struct ep93xx_ac97_info *info,
	unsigned reg, unsigned val)
	{
	__raw_writel(val, info->regs + reg);
	}

	static unsigned short ep93xx_ac97_read(struct snd_ac97 *ac97,
	unsigned short reg)
	{
	struct ep93xx_ac97_info *info = ep93xx_ac97_info;
	unsigned short val;

	mutex_lock(&info->lock);

	ep93xx_ac97_write_reg(info, AC97S1DATA, reg);
	ep93xx_ac97_write_reg(info, AC97IM, AC97_SLOT2RXVALID);
	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT)) {
	dev_warn(info->dev, "timeout reading register %x\n", reg);
	mutex_unlock(&info->lock);
	return -ETIMEDOUT;
	}
	val = (unsigned short)ep93xx_ac97_read_reg(info, AC97S2DATA);

	mutex_unlock(&info->lock);
	return val;
	}

	static void ep93xx_ac97_write(struct snd_ac97 *ac97,
	unsigned short reg,
	unsigned short val)
	{
	struct ep93xx_ac97_info *info = ep93xx_ac97_info;

	mutex_lock(&info->lock);

	/*
	* Writes to the codec need to be done so that slot 2 is filled in
	* before slot 1.
	*/
	ep93xx_ac97_write_reg(info, AC97S2DATA, val);
	ep93xx_ac97_write_reg(info, AC97S1DATA, reg);

	ep93xx_ac97_write_reg(info, AC97IM, AC97_SLOT2TXCOMPLETE);
	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT))
	dev_warn(info->dev, "timeout writing register %x\n", reg);

	mutex_unlock(&info->lock);
	}

	static void ep93xx_ac97_warm_reset(struct snd_ac97 *ac97)
	{
	struct ep93xx_ac97_info *info = ep93xx_ac97_info;

	mutex_lock(&info->lock);

	/*
	* We are assuming that before this functions gets called, the codec
	* BIT_CLK is stopped by forcing the codec into powerdown mode. We can
	* control the SYNC signal directly via AC97SYNC register. Using
	* TIMEDSYNC the controller will keep the SYNC high > 1us.
	*/
	ep93xx_ac97_write_reg(info, AC97SYNC, AC97SYNC_TIMEDSYNC);
	ep93xx_ac97_write_reg(info, AC97IM, AC97_CODECREADY);
	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT))
	dev_warn(info->dev, "codec warm reset timeout\n");

	mutex_unlock(&info->lock);
	}

	static void ep93xx_ac97_cold_reset(struct snd_ac97 *ac97)
	{
	struct ep93xx_ac97_info *info = ep93xx_ac97_info;

	mutex_lock(&info->lock);

	/*
	* For doing cold reset, we disable the AC97 controller interface, clear
	* WINT and CODECREADY bits, and finally enable the interface again.
	*/
	ep93xx_ac97_write_reg(info, AC97GCR, 0);
	ep93xx_ac97_write_reg(info, AC97EOI, AC97EOI_CODECREADY \| AC97EOI_WINT);
	ep93xx_ac97_write_reg(info, AC97GCR, AC97GCR_AC97IFE);

	/*
	* Now, assert the reset and wait for the codec to become ready.
	*/
	ep93xx_ac97_write_reg(info, AC97RESET, AC97RESET_TIMEDRESET);
	ep93xx_ac97_write_reg(info, AC97IM, AC97_CODECREADY);
	if (!wait_for_completion_timeout(&info->done, AC97_TIMEOUT))
	dev_warn(info->dev, "codec cold reset timeout\n");

	/*
	* Give the codec some time to come fully out from the reset. This way
	* we ensure that the subsequent reads/writes will work.
	*/
	usleep_range(15000, 20000);

	mutex_unlock(&info->lock);
	}

	static irqreturn_t ep93xx_ac97_interrupt(int irq, void *dev_id)
	{
	struct ep93xx_ac97_info *info = dev_id;
	unsigned status, mask;

	/*
	* Just mask out the interrupt and wake up the waiting thread.
	* Interrupts are cleared via reading/writing to slot 1 & 2 registers by
	* the waiting thread.
	*/
	status = ep93xx_ac97_read_reg(info, AC97GIS);
	mask = ep93xx_ac97_read_reg(info, AC97IM);
	mask &= ~status;
	ep93xx_ac97_write_reg(info, AC97IM, mask);

	complete(&info->done);
	return IRQ_HANDLED;
	}

	static struct snd_ac97_bus_ops ep93xx_ac97_ops = {
	.read = ep93xx_ac97_read,
	.write = ep93xx_ac97_write,
	.reset = ep93xx_ac97_cold_reset,
	.warm_reset = ep93xx_ac97_warm_reset,
	};

	static int ep93xx_ac97_trigger(struct snd_pcm_substream *substream,
	int cmd, struct snd_soc_dai *dai)
	{
	struct ep93xx_ac97_info *info = snd_soc_dai_get_drvdata(dai);
	unsigned v = 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) {
	/*
	* Enable compact mode, TX slots 3 & 4, and the TX FIFO
	* itself.
	*/
	v \|= AC97TXCR_CM;
	v \|= AC97TXCR_TX3 \| AC97TXCR_TX4;
	v \|= AC97TXCR_TEN;
	ep93xx_ac97_write_reg(info, AC97TXCR(1), v);
	} else {
	/*
	* Enable compact mode, RX slots 3 & 4, and the RX FIFO
	* itself.
	*/
	v \|= AC97RXCR_CM;
	v \|= AC97RXCR_RX3 \| AC97RXCR_RX4;
	v \|= AC97RXCR_REN;
	ep93xx_ac97_write_reg(info, AC97RXCR(1), v);
	}
	break;

	case SNDRV_PCM_TRIGGER_STOP:
	case SNDRV_PCM_TRIGGER_SUSPEND:
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
	/*
	* As per Cirrus EP93xx errata described below:
	*
	* http://www.cirrus.com/en/pubs/errata/ER667E2B.pdf
	*
	* we will wait for the TX FIFO to be empty before
	* clearing the TEN bit.
	*/
	unsigned long timeout = jiffies + AC97_TIMEOUT;

	do {
	v = ep93xx_ac97_read_reg(info, AC97SR(1));
	if (time_after(jiffies, timeout)) {
	dev_warn(info->dev, "TX timeout\n");
	break;
	}
	} while (!(v & (AC97SR_TXFE \| AC97SR_TXUE)));

	/* disable the TX FIFO */
	ep93xx_ac97_write_reg(info, AC97TXCR(1), 0);
	} else {
	/* disable the RX FIFO */
	ep93xx_ac97_write_reg(info, AC97RXCR(1), 0);
	}
	break;

	default:
	dev_warn(info->dev, "unknown command %d\n", cmd);
	return -EINVAL;
	}

	return 0;
	}

	static int ep93xx_ac97_dai_probe(struct snd_soc_dai *dai)
	{
	struct ep93xx_ac97_info *info = snd_soc_dai_get_drvdata(dai);

	info->dma_params_tx.filter_data = &ep93xx_ac97_pcm_out;
	info->dma_params_rx.filter_data = &ep93xx_ac97_pcm_in;

	dai->playback_dma_data = &info->dma_params_tx;
	dai->capture_dma_data = &info->dma_params_rx;

	return 0;
	}

	static const struct snd_soc_dai_ops ep93xx_ac97_dai_ops = {
	.trigger = ep93xx_ac97_trigger,
	};

	static struct snd_soc_dai_driver ep93xx_ac97_dai = {
	.name = "ep93xx-ac97",
	.id = 0,
	.ac97_control = 1,
	.probe = ep93xx_ac97_dai_probe,
	.playback = {
	.stream_name = "AC97 Playback",
	.channels_min = 2,
	.channels_max = 2,
	.rates = SNDRV_PCM_RATE_8000_48000,
	.formats = SNDRV_PCM_FMTBIT_S16_LE,
	},
	.capture = {
	.stream_name = "AC97 Capture",
	.channels_min = 2,
	.channels_max = 2,
	.rates = SNDRV_PCM_RATE_8000_48000,
	.formats = SNDRV_PCM_FMTBIT_S16_LE,
	},
	.ops = &ep93xx_ac97_dai_ops,
	};

	static const struct snd_soc_component_driver ep93xx_ac97_component = {
	.name = "ep93xx-ac97",
	};

	static int ep93xx_ac97_probe(struct platform_device *pdev)
	{
	struct ep93xx_ac97_info *info;
	struct resource *res;
	unsigned int irq;
	int ret;

	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
	if (!info)
	return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	info->regs = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(info->regs))
	return PTR_ERR(info->regs);

	irq = platform_get_irq(pdev, 0);
	if (!irq)
	return -ENODEV;

	ret = devm_request_irq(&pdev->dev, irq, ep93xx_ac97_interrupt,
	IRQF_TRIGGER_HIGH, pdev->name, info);
	if (ret)
	goto fail;

	dev_set_drvdata(&pdev->dev, info);

	mutex_init(&info->lock);
	init_completion(&info->done);
	info->dev = &pdev->dev;

	ep93xx_ac97_info = info;
	platform_set_drvdata(pdev, info);

	ret = snd_soc_set_ac97_ops(&ep93xx_ac97_ops);
	if (ret)
	goto fail;

	ret = snd_soc_register_component(&pdev->dev, &ep93xx_ac97_component,
	&ep93xx_ac97_dai, 1);
	if (ret)
	goto fail;

	ret = devm_ep93xx_pcm_platform_register(&pdev->dev);
	if (ret)
	goto fail_unregister;

	return 0;

	fail_unregister:
	snd_soc_unregister_component(&pdev->dev);
	fail:
	ep93xx_ac97_info = NULL;
	snd_soc_set_ac97_ops(NULL);
	return ret;
	}

	static int ep93xx_ac97_remove(struct platform_device *pdev)
	{
	struct ep93xx_ac97_info *info = platform_get_drvdata(pdev);

	snd_soc_unregister_component(&pdev->dev);

	/* disable the AC97 controller */
	ep93xx_ac97_write_reg(info, AC97GCR, 0);

	ep93xx_ac97_info = NULL;

	snd_soc_set_ac97_ops(NULL);

	return 0;
	}

	static struct platform_driver ep93xx_ac97_driver = {
	.probe = ep93xx_ac97_probe,
	.remove = ep93xx_ac97_remove,
	.driver = {
	.name = "ep93xx-ac97",
	.owner = THIS_MODULE,
	},
	};

	module_platform_driver(ep93xx_ac97_driver);

	MODULE_DESCRIPTION("EP93xx AC97 ASoC Driver");
	MODULE_AUTHOR("Mika Westerberg <mika.westerberg@iki.fi>");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:ep93xx-ac97");