/*
 * Serial Sound Interface (I2S) support for SH7760/SH7780
 *
 * Copyright (c) 2007 Manuel Lauss <mano@roarinelk.homelinux.net>
 *
 *  licensed under the terms outlined in the file COPYING at the root
 *  of the linux kernel sources.
 *
 * dont forget to set IPSEL/OMSEL register bits (in your board code) to
 * enable SSI output pins!
 */

/*
 * LIMITATIONS:
 *      The SSI unit has only one physical data line, so full duplex is
 *      impossible.  This can be remedied  on the  SH7760 by  using the
 *      other SSI unit for recording; however the SH7780 has only 1 SSI
 *      unit, and its pins are shared with the AC97 unit,  among others.
 *
 * FEATURES:
 *      The SSI features "compressed mode": in this mode it continuously
 *      streams PCM data over the I2S lines and uses LRCK as a handshake
 *      signal.  Can be used to send compressed data (AC3/DTS) to a DSP.
 *      The number of bits sent over the wire in a frame can be adjusted
 *      and can be independent from the actual sample bit depth. This is
 *      useful to support TDM mode codecs like the AD1939 which have a
 *      fixed TDM slot size, regardless of sample resolution.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/initval.h>
#include <sound/soc.h>
#include <asm/io.h>

#define SSICR   0x00
#define SSISR   0x04

#define CR_DMAEN        (1 << 28)
#define CR_CHNL_SHIFT   22
#define CR_CHNL_MASK    (3 << CR_CHNL_SHIFT)
#define CR_DWL_SHIFT    19
#define CR_DWL_MASK     (7 << CR_DWL_SHIFT)
#define CR_SWL_SHIFT    16
#define CR_SWL_MASK     (7 << CR_SWL_SHIFT)
#define CR_SCK_MASTER   (1 << 15)       /* bitclock master bit */
#define CR_SWS_MASTER   (1 << 14)       /* wordselect master bit */
#define CR_SCKP         (1 << 13)       /* I2Sclock polarity */
#define CR_SWSP         (1 << 12)       /* LRCK polarity */
#define CR_SPDP         (1 << 11)
#define CR_SDTA         (1 << 10)       /* i2s alignment (msb/lsb) */
#define CR_PDTA         (1 << 9)        /* fifo data alignment */
#define CR_DEL          (1 << 8)        /* delay data by 1 i2sclk */
#define CR_BREN         (1 << 7)        /* clock gating in burst mode */
#define CR_CKDIV_SHIFT  4
#define CR_CKDIV_MASK   (7 << CR_CKDIV_SHIFT)   /* bitclock divider */
#define CR_MUTE         (1 << 3)        /* SSI mute */
#define CR_CPEN         (1 << 2)        /* compressed mode */
#define CR_TRMD         (1 << 1)        /* transmit/receive select */
#define CR_EN           (1 << 0)        /* enable SSI */

#define SSIREG(reg)     (*(unsigned long *)(ssi->mmio + (reg)))

struct ssi_priv {
        unsigned long mmio;
        unsigned long sysclk;
        int inuse;
} ssi_cpu_data[] = {
#if defined(CONFIG_CPU_SUBTYPE_SH7760)
        {
                .mmio   = 0xFE680000,
        },
        {
                .mmio   = 0xFE690000,
        },
#elif defined(CONFIG_CPU_SUBTYPE_SH7780)
        {
                .mmio   = 0xFFE70000,
        },
#else
#error "Unsupported SuperH SoC"
#endif
};

/*
 * track usage of the SSI; it is simplex-only so prevent attempts of
 * concurrent playback + capture. FIXME: any locking required?
 */
static int ssi_startup(struct snd_pcm_substream *substream,
                       struct snd_soc_dai *dai)
{
        struct snd_soc_pcm_runtime *rtd = substream->private_data;
        struct ssi_priv *ssi = &ssi_cpu_data[rtd->dai->cpu_dai->id];
        if (ssi->inuse) {
                pr_debug("ssi: already in use!\n");
                return -EBUSY;
        } else
                ssi->inuse = 1;
        return 0;
}

static void ssi_shutdown(struct snd_pcm_substream *substream,
                         struct snd_soc_dai *dai)
{
        struct snd_soc_pcm_runtime *rtd = substream->private_data;
        struct ssi_priv *ssi = &ssi_cpu_data[rtd->dai->cpu_dai->id];

        ssi->inuse = 0;
}

static int ssi_trigger(struct snd_pcm_substream *substream, int cmd,
                       struct snd_soc_dai *dai)
{
        struct snd_soc_pcm_runtime *rtd = substream->private_data;
        struct ssi_priv *ssi = &ssi_cpu_data[rtd->dai->cpu_dai->id];

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
                SSIREG(SSICR) |= CR_DMAEN | CR_EN;
                break;
        case SNDRV_PCM_TRIGGER_STOP:
                SSIREG(SSICR) &= ~(CR_DMAEN | CR_EN);
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int ssi_hw_params(struct snd_pcm_substream *substream,
                         struct snd_pcm_hw_params *params,
                         struct snd_soc_dai *dai)
{
        struct snd_soc_pcm_runtime *rtd = substream->private_data;
        struct ssi_priv *ssi = &ssi_cpu_data[rtd->dai->cpu_dai->id];
        unsigned long ssicr = SSIREG(SSICR);
        unsigned int bits, channels, swl, recv, i;

        channels = params_channels(params);
        bits = params->msbits;
        recv = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ? 0 : 1;

        pr_debug("ssi_hw_params() enter\nssicr was    %08lx\n", ssicr);
        pr_debug("bits: %u channels: %u\n", bits, channels);

        ssicr &= ~(CR_TRMD | CR_CHNL_MASK | CR_DWL_MASK | CR_PDTA |
                   CR_SWL_MASK);

        /* direction (send/receive) */
        if (!recv)
                ssicr |= CR_TRMD;       /* transmit */

        /* channels */
        if ((channels < 2) || (channels > 8) || (channels & 1)) {
                pr_debug("ssi: invalid number of channels\n");
                return -EINVAL;
        }
        ssicr |= ((channels >> 1) - 1) << CR_CHNL_SHIFT;

        /* DATA WORD LENGTH (DWL): databits in audio sample */
        i = 0;
        switch (bits) {
        case 32: ++i;
        case 24: ++i;
        case 22: ++i;
        case 20: ++i;
        case 18: ++i;
        case 16: ++i;
                 ssicr |= i << CR_DWL_SHIFT;
        case 8:  break;
        default:
                pr_debug("ssi: invalid sample width\n");
                return -EINVAL;
        }

        /*
         * SYSTEM WORD LENGTH: size in bits of half a frame over the I2S
         * wires. This is usually bits_per_sample x channels/2;  i.e. in
         * Stereo mode  the SWL equals DWL.  SWL can  be bigger than the
         * product of (channels_per_slot x samplebits), e.g.  for codecs
         * like the AD1939 which  only accept 32bit wide TDM slots.  For
         * "standard" I2S operation we set SWL = chans / 2 * DWL here.
         * Waiting for ASoC to get TDM support ;-)
         */
        if ((bits > 16) && (bits <= 24)) {
                bits = 24;      /* these are padded by the SSI */
                /*ssicr |= CR_PDTA;*/ /* cpu/data endianness ? */
        }
        i = 0;
        swl = (bits * channels) / 2;
        switch (swl) {
        case 256: ++i;
        case 128: ++i;
        case 64:  ++i;
        case 48:  ++i;
        case 32:  ++i;
        case 16:  ++i;
                  ssicr |= i << CR_SWL_SHIFT;
        case 8:   break;
        default:
                pr_debug("ssi: invalid system word length computed\n");
                return -EINVAL;
        }

        SSIREG(SSICR) = ssicr;

        pr_debug("ssi_hw_params() leave\nssicr is now %08lx\n", ssicr);
        return 0;
}

static int ssi_set_sysclk(struct snd_soc_dai *cpu_dai, int clk_id,
                          unsigned int freq, int dir)
{
        struct ssi_priv *ssi = &ssi_cpu_data[cpu_dai->id];

        ssi->sysclk = freq;

        return 0;
}

/*
 * This divider is used to generate the SSI_SCK (I2S bitclock) from the
 * clock at the HAC_BIT_CLK ("oversampling clock") pin.
 */
static int ssi_set_clkdiv(struct snd_soc_dai *dai, int did, int div)
{
        struct ssi_priv *ssi = &ssi_cpu_data[dai->id];
        unsigned long ssicr;
        int i;

        i = 0;
        ssicr = SSIREG(SSICR) & ~CR_CKDIV_MASK;
        switch (div) {
        case 16: ++i;
        case 8:  ++i;
        case 4:  ++i;
        case 2:  ++i;
                 SSIREG(SSICR) = ssicr | (i << CR_CKDIV_SHIFT);
        case 1:  break;
        default:
                pr_debug("ssi: invalid sck divider %d\n", div);
                return -EINVAL;
        }

        return 0;
}

static int ssi_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
{
        struct ssi_priv *ssi = &ssi_cpu_data[dai->id];
        unsigned long ssicr = SSIREG(SSICR);

        pr_debug("ssi_set_fmt()\nssicr was    0x%08lx\n", ssicr);

        ssicr &= ~(CR_DEL | CR_PDTA | CR_BREN | CR_SWSP | CR_SCKP |
                   CR_SWS_MASTER | CR_SCK_MASTER);

        switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
        case SND_SOC_DAIFMT_I2S:
                break;
        case SND_SOC_DAIFMT_RIGHT_J:
                ssicr |= CR_DEL | CR_PDTA;
                break;
        case SND_SOC_DAIFMT_LEFT_J:
                ssicr |= CR_DEL;
                break;
        default:
                pr_debug("ssi: unsupported format\n");
                return -EINVAL;
        }

        switch (fmt & SND_SOC_DAIFMT_CLOCK_MASK) {
        case SND_SOC_DAIFMT_CONT:
                break;
        case SND_SOC_DAIFMT_GATED:
                ssicr |= CR_BREN;
                break;
        }

        switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
        case SND_SOC_DAIFMT_NB_NF:
                ssicr |= CR_SCKP;       /* sample data at low clkedge */
                break;
        case SND_SOC_DAIFMT_NB_IF:
                ssicr |= CR_SCKP | CR_SWSP;
                break;
        case SND_SOC_DAIFMT_IB_NF:
                break;
        case SND_SOC_DAIFMT_IB_IF:
                ssicr |= CR_SWSP;       /* word select starts low */
                break;
        default:
                pr_debug("ssi: invalid inversion\n");
                return -EINVAL;
        }

        switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
        case SND_SOC_DAIFMT_CBM_CFM:
                break;
        case SND_SOC_DAIFMT_CBS_CFM:
                ssicr |= CR_SCK_MASTER;
                break;
        case SND_SOC_DAIFMT_CBM_CFS:
                ssicr |= CR_SWS_MASTER;
                break;
        case SND_SOC_DAIFMT_CBS_CFS:
                ssicr |= CR_SWS_MASTER | CR_SCK_MASTER;
                break;
        default:
                pr_debug("ssi: invalid master/slave configuration\n");
                return -EINVAL;
        }

        SSIREG(SSICR) = ssicr;
        pr_debug("ssi_set_fmt() leave\nssicr is now 0x%08lx\n", ssicr);

        return 0;
}

/* the SSI depends on an external clocksource (at HAC_BIT_CLK) even in
 * Master mode,  so really this is board specific;  the SSI can do any
 * rate with the right bitclk and divider settings.
 */
#define SSI_RATES       \
        SNDRV_PCM_RATE_8000_192000

/* the SSI can do 8-32 bit samples, with 8 possible channels */
#define SSI_FMTS        \
        (SNDRV_PCM_FMTBIT_S8      | SNDRV_PCM_FMTBIT_U8      |  \
         SNDRV_PCM_FMTBIT_S16_LE  | SNDRV_PCM_FMTBIT_U16_LE  |  \
         SNDRV_PCM_FMTBIT_S20_3LE | SNDRV_PCM_FMTBIT_U20_3LE |  \
         SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_U24_3LE |  \
         SNDRV_PCM_FMTBIT_S32_LE  | SNDRV_PCM_FMTBIT_U32_LE)

static struct snd_soc_dai_ops ssi_dai_ops = {
        .startup        = ssi_startup,
        .shutdown       = ssi_shutdown,
        .trigger        = ssi_trigger,
        .hw_params      = ssi_hw_params,
        .set_sysclk     = ssi_set_sysclk,
        .set_clkdiv     = ssi_set_clkdiv,
        .set_fmt        = ssi_set_fmt,
};

struct snd_soc_dai sh4_ssi_dai[] = {
{
        .name                   = "SSI0",
        .id                     = 0,
        .playback = {
                .rates          = SSI_RATES,
                .formats        = SSI_FMTS,
                .channels_min   = 2,
                .channels_max   = 8,
        },
        .capture = {
                .rates          = SSI_RATES,
                .formats        = SSI_FMTS,
                .channels_min   = 2,
                .channels_max   = 8,
        },
        .ops = &ssi_dai_ops,
},
#ifdef CONFIG_CPU_SUBTYPE_SH7760
{
        .name                   = "SSI1",
        .id                     = 1,
        .playback = {
                .rates          = SSI_RATES,
                .formats        = SSI_FMTS,
                .channels_min   = 2,
                .channels_max   = 8,
        },
        .capture = {
                .rates          = SSI_RATES,
                .formats        = SSI_FMTS,
                .channels_min   = 2,
                .channels_max   = 8,
        },
        .ops = &ssi_dai_ops,
},
#endif
};
EXPORT_SYMBOL_GPL(sh4_ssi_dai);

static int __init sh4_ssi_init(void)
{
        return snd_soc_register_dais(sh4_ssi_dai, ARRAY_SIZE(sh4_ssi_dai));
}
module_init(sh4_ssi_init);

static void __exit sh4_ssi_exit(void)
{
        snd_soc_unregister_dais(sh4_ssi_dai, ARRAY_SIZE(sh4_ssi_dai));
}
module_exit(sh4_ssi_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SuperH onchip SSI (I2S) audio driver");
MODULE_AUTHOR("Manuel Lauss <mano@roarinelk.homelinux.net>");