/*
 * 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,
        .bus_control    = true,
        .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",
        },
};

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");