abdac.c

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/*
 * Driver for the Atmel on-chip Audio Bitstream DAC (ABDAC)
 *
 * Copyright (C) 2006-2009 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/bitmap.h>
#include <linux/dw_dmac.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/types.h>
#include <linux/io.h>

#include <sound/core.h>
#include <sound/initval.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/atmel-abdac.h>

/* DAC register offsets */
#define DAC_DATA                                0x0000
#define DAC_CTRL                                0x0008
#define DAC_INT_MASK                            0x000c
#define DAC_INT_EN                              0x0010
#define DAC_INT_DIS                             0x0014
#define DAC_INT_CLR                             0x0018
#define DAC_INT_STATUS                          0x001c

/* Bitfields in CTRL */
#define DAC_SWAP_OFFSET                         30
#define DAC_SWAP_SIZE                           1
#define DAC_EN_OFFSET                           31
#define DAC_EN_SIZE                             1

/* Bitfields in INT_MASK/INT_EN/INT_DIS/INT_STATUS/INT_CLR */
#define DAC_UNDERRUN_OFFSET                     28
#define DAC_UNDERRUN_SIZE                       1
#define DAC_TX_READY_OFFSET                     29
#define DAC_TX_READY_SIZE                       1

/* Bit manipulation macros */
#define DAC_BIT(name)                   \
    (1 << DAC_##name##_OFFSET)
#define DAC_BF(name, value)             \
    (((value) & ((1 << DAC_##name##_SIZE) - 1)) \
     << DAC_##name##_OFFSET)
#define DAC_BFEXT(name, value)              \
    (((value) >> DAC_##name##_OFFSET)       \
     & ((1 << DAC_##name##_SIZE) - 1))
#define DAC_BFINS(name, value, old)         \
    (((old) & ~(((1 << DAC_##name##_SIZE) - 1)  \
            << DAC_##name##_OFFSET))        \
     | DAC_BF(name, value))

/* Register access macros */
#define dac_readl(port, reg)                \
    __raw_readl((port)->regs + DAC_##reg)
#define dac_writel(port, reg, value)            \
    __raw_writel((value), (port)->regs + DAC_##reg)

/*
 * ABDAC supports a maximum of 6 different rates from a generic clock. The
 * generic clock has a power of two divider, which gives 6 steps from 192 kHz
 * to 5112 Hz.
 */
#define MAX_NUM_RATES   6
/* ALSA seems to use rates between 192000 Hz and 5112 Hz. */
#define RATE_MAX    192000
#define RATE_MIN    5112

enum {
    DMA_READY = 0,
};

struct atmel_abdac_dma {
    struct dma_chan     *chan;
    struct dw_cyclic_desc   *cdesc;
};

struct atmel_abdac {
    struct clk              *pclk;
    struct clk              *sample_clk;
    struct platform_device          *pdev;
    struct atmel_abdac_dma          dma;

    struct snd_pcm_hw_constraint_list   constraints_rates;
    struct snd_pcm_substream        *substream;
    struct snd_card             *card;
    struct snd_pcm              *pcm;

    void __iomem                *regs;
    unsigned long               flags;
    unsigned int                rates[MAX_NUM_RATES];
    unsigned int                rates_num;
    int                 irq;
};

#define get_dac(card) ((struct atmel_abdac *)(card)->private_data)

/* This function is called by the DMA driver. */
static void atmel_abdac_dma_period_done(void *arg)
{
    struct atmel_abdac *dac = arg;
    snd_pcm_period_elapsed(dac->substream);
}

static int atmel_abdac_prepare_dma(struct atmel_abdac *dac,
        struct snd_pcm_substream *substream,
        enum dma_data_direction direction)
{
    struct dma_chan         *chan = dac->dma.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(&dac->pdev->dev, "too complex transfer\n");
        return -EINVAL;
    }

    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, DMA_MEM_TO_DEV);
    if (IS_ERR(cdesc)) {
        dev_dbg(&dac->pdev->dev, "could not prepare cyclic DMA\n");
        return PTR_ERR(cdesc);
    }

    cdesc->period_callback = atmel_abdac_dma_period_done;
    cdesc->period_callback_param = dac;

    dac->dma.cdesc = cdesc;

    set_bit(DMA_READY, &dac->flags);

    return 0;
}

static struct snd_pcm_hardware atmel_abdac_hw = {
    .info           = (SNDRV_PCM_INFO_MMAP
                  | SNDRV_PCM_INFO_MMAP_VALID
                  | SNDRV_PCM_INFO_INTERLEAVED
                  | SNDRV_PCM_INFO_BLOCK_TRANSFER
                  | SNDRV_PCM_INFO_RESUME
                  | SNDRV_PCM_INFO_PAUSE),
    .formats        = (SNDRV_PCM_FMTBIT_S16_BE),
    .rates          = (SNDRV_PCM_RATE_KNOT),
    .rate_min       = RATE_MIN,
    .rate_max       = RATE_MAX,
    .channels_min       = 2,
    .channels_max       = 2,
    .buffer_bytes_max   = 64 * 4096,
    .period_bytes_min   = 4096,
    .period_bytes_max   = 4096,
    .periods_min        = 6,
    .periods_max        = 64,
};

static int atmel_abdac_open(struct snd_pcm_substream *substream)
{
    struct atmel_abdac *dac = snd_pcm_substream_chip(substream);

    dac->substream = substream;
    atmel_abdac_hw.rate_max = dac->rates[dac->rates_num - 1];
    atmel_abdac_hw.rate_min = dac->rates[0];
    substream->runtime->hw = atmel_abdac_hw;

    return snd_pcm_hw_constraint_list(substream->runtime, 0,
            SNDRV_PCM_HW_PARAM_RATE, &dac->constraints_rates);
}

static int atmel_abdac_close(struct snd_pcm_substream *substream)
{
    struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
    dac->substream = NULL;
    return 0;
}

static int atmel_abdac_hw_params(struct snd_pcm_substream *substream,
        struct snd_pcm_hw_params *hw_params)
{
    struct atmel_abdac *dac = 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_READY, &dac->flags))
            dw_dma_cyclic_free(dac->dma.chan);

    return retval;
}

static int atmel_abdac_hw_free(struct snd_pcm_substream *substream)
{
    struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
    if (test_and_clear_bit(DMA_READY, &dac->flags))
        dw_dma_cyclic_free(dac->dma.chan);
    return snd_pcm_lib_free_pages(substream);
}

static int atmel_abdac_prepare(struct snd_pcm_substream *substream)
{
    struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
    int retval;

    retval = clk_set_rate(dac->sample_clk, 256 * substream->runtime->rate);
    if (retval)
        return retval;

    if (!test_bit(DMA_READY, &dac->flags))
        retval = atmel_abdac_prepare_dma(dac, substream, DMA_TO_DEVICE);

    return retval;
}

static int atmel_abdac_trigger(struct snd_pcm_substream *substream, int cmd)
{
    struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
    int retval = 0;

    switch (cmd) {
    case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: /* fall through */
    case SNDRV_PCM_TRIGGER_RESUME: /* fall through */
    case SNDRV_PCM_TRIGGER_START:
        clk_enable(dac->sample_clk);
        retval = dw_dma_cyclic_start(dac->dma.chan);
        if (retval)
            goto out;
        dac_writel(dac, CTRL, DAC_BIT(EN));
        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(dac->dma.chan);
        dac_writel(dac, DATA, 0);
        dac_writel(dac, CTRL, 0);
        clk_disable(dac->sample_clk);
        break;
    default:
        retval = -EINVAL;
        break;
    }
out:
    return retval;
}

static snd_pcm_uframes_t
atmel_abdac_pointer(struct snd_pcm_substream *substream)
{
    struct atmel_abdac  *dac = 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(dac->dma.chan);
    bytes -= runtime->dma_addr;

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

    return frames;
}

static irqreturn_t abdac_interrupt(int irq, void *dev_id)
{
    struct atmel_abdac *dac = dev_id;
    u32 status;

    status = dac_readl(dac, INT_STATUS);
    if (status & DAC_BIT(UNDERRUN)) {
        dev_err(&dac->pdev->dev, "underrun detected\n");
        dac_writel(dac, INT_CLR, DAC_BIT(UNDERRUN));
    } else {
        dev_err(&dac->pdev->dev, "spurious interrupt (status=0x%x)\n",
            status);
        dac_writel(dac, INT_CLR, status);
    }

    return IRQ_HANDLED;
}

static struct snd_pcm_ops atmel_abdac_ops = {
    .open       = atmel_abdac_open,
    .close      = atmel_abdac_close,
    .ioctl      = snd_pcm_lib_ioctl,
    .hw_params  = atmel_abdac_hw_params,
    .hw_free    = atmel_abdac_hw_free,
    .prepare    = atmel_abdac_prepare,
    .trigger    = atmel_abdac_trigger,
    .pointer    = atmel_abdac_pointer,
};

static int __devinit atmel_abdac_pcm_new(struct atmel_abdac *dac)
{
    struct snd_pcm_hardware hw = atmel_abdac_hw;
    struct snd_pcm *pcm;
    int retval;

    retval = snd_pcm_new(dac->card, dac->card->shortname,
            dac->pdev->id, 1, 0, &pcm);
    if (retval)
        return retval;

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

    snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &atmel_abdac_ops);

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

    return retval;
}

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 int set_sample_rates(struct atmel_abdac *dac)
{
    long new_rate = RATE_MAX;
    int retval = -EINVAL;
    int index = 0;

    /* we start at 192 kHz and work our way down to 5112 Hz */
    while (new_rate >= RATE_MIN && index < (MAX_NUM_RATES + 1)) {
        new_rate = clk_round_rate(dac->sample_clk, 256 * new_rate);
        if (new_rate < 0)
            break;
        /* make sure we are below the ABDAC clock */
        if (new_rate <= clk_get_rate(dac->pclk)) {
            dac->rates[index] = new_rate / 256;
            index++;
        }
        /* divide by 256 and then by two to get next rate */
        new_rate /= 256 * 2;
    }

    if (index) {
        int i;

        /* reverse array, smallest go first */
        for (i = 0; i < (index / 2); i++) {
            unsigned int tmp = dac->rates[index - 1 - i];
            dac->rates[index - 1 - i] = dac->rates[i];
            dac->rates[i] = tmp;
        }

        dac->constraints_rates.count = index;
        dac->constraints_rates.list = dac->rates;
        dac->constraints_rates.mask = 0;
        dac->rates_num = index;

        retval = 0;
    }

    return retval;
}

static int __devinit atmel_abdac_probe(struct platform_device *pdev)
{
    struct snd_card     *card;
    struct atmel_abdac  *dac;
    struct resource     *regs;
    struct atmel_abdac_pdata    *pdata;
    struct clk      *pclk;
    struct clk      *sample_clk;
    int         retval;
    int         irq;

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

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

    pdata = pdev->dev.platform_data;
    if (!pdata) {
        dev_dbg(&pdev->dev, "no platform data\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);
    }
    sample_clk = clk_get(&pdev->dev, "sample_clk");
    if (IS_ERR(sample_clk)) {
        dev_dbg(&pdev->dev, "no sample clock\n");
        retval = PTR_ERR(sample_clk);
        goto out_put_pclk;
    }
    clk_enable(pclk);

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

    dac = get_dac(card);

    dac->irq = irq;
    dac->card = card;
    dac->pclk = pclk;
    dac->sample_clk = sample_clk;
    dac->pdev = pdev;

    retval = set_sample_rates(dac);
    if (retval < 0) {
        dev_dbg(&pdev->dev, "could not set supported rates\n");
        goto out_free_card;
    }

    dac->regs = ioremap(regs->start, resource_size(regs));
    if (!dac->regs) {
        dev_dbg(&pdev->dev, "could not remap register memory\n");
        retval = -ENOMEM;
        goto out_free_card;
    }

    /* make sure the DAC is silent and disabled */
    dac_writel(dac, DATA, 0);
    dac_writel(dac, CTRL, 0);

    retval = request_irq(irq, abdac_interrupt, 0, "abdac", dac);
    if (retval) {
        dev_dbg(&pdev->dev, "could not request irq\n");
        goto out_unmap_regs;
    }

    snd_card_set_dev(card, &pdev->dev);

    if (pdata->dws.dma_dev) {
        dma_cap_mask_t mask;

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

        dac->dma.chan = dma_request_channel(mask, filter, &pdata->dws);
        if (dac->dma.chan) {
            struct dma_slave_config dma_conf = {
                .dst_addr = regs->start + DAC_DATA,
                .dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
                .src_maxburst = 1,
                .dst_maxburst = 1,
                .direction = DMA_MEM_TO_DEV,
                .device_fc = false,
            };

            dmaengine_slave_config(dac->dma.chan, &dma_conf);
        }
    }
    if (!pdata->dws.dma_dev || !dac->dma.chan) {
        dev_dbg(&pdev->dev, "DMA not available\n");
        retval = -ENODEV;
        goto out_unset_card_dev;
    }

    strcpy(card->driver, "Atmel ABDAC");
    strcpy(card->shortname, "Atmel ABDAC");
    sprintf(card->longname, "Atmel Audio Bitstream DAC");

    retval = atmel_abdac_pcm_new(dac);
    if (retval) {
        dev_dbg(&pdev->dev, "could not register ABDAC pcm device\n");
        goto out_release_dma;
    }

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

    platform_set_drvdata(pdev, card);

    dev_info(&pdev->dev, "Atmel ABDAC at 0x%p using %s\n",
            dac->regs, dev_name(&dac->dma.chan->dev->device));

    return retval;

out_release_dma:
    dma_release_channel(dac->dma.chan);
    dac->dma.chan = NULL;
out_unset_card_dev:
    snd_card_set_dev(card, NULL);
    free_irq(irq, dac);
out_unmap_regs:
    iounmap(dac->regs);
out_free_card:
    snd_card_free(card);
out_put_sample_clk:
    clk_put(sample_clk);
    clk_disable(pclk);
out_put_pclk:
    clk_put(pclk);
    return retval;
}

#ifdef CONFIG_PM_SLEEP
static int atmel_abdac_suspend(struct device *pdev)
{
    struct snd_card *card = dev_get_drvdata(pdev);
    struct atmel_abdac *dac = card->private_data;

    dw_dma_cyclic_stop(dac->dma.chan);
    clk_disable(dac->sample_clk);
    clk_disable(dac->pclk);

    return 0;
}

static int atmel_abdac_resume(struct device *pdev)
{
    struct snd_card *card = dev_get_drvdata(pdev);
    struct atmel_abdac *dac = card->private_data;

    clk_enable(dac->pclk);
    clk_enable(dac->sample_clk);
    if (test_bit(DMA_READY, &dac->flags))
        dw_dma_cyclic_start(dac->dma.chan);

    return 0;
}

static SIMPLE_DEV_PM_OPS(atmel_abdac_pm, atmel_abdac_suspend, atmel_abdac_resume);
#define ATMEL_ABDAC_PM_OPS  &atmel_abdac_pm
#else
#define ATMEL_ABDAC_PM_OPS  NULL
#endif

static int __devexit atmel_abdac_remove(struct platform_device *pdev)
{
    struct snd_card *card = platform_get_drvdata(pdev);
    struct atmel_abdac *dac = get_dac(card);

    clk_put(dac->sample_clk);
    clk_disable(dac->pclk);
    clk_put(dac->pclk);

    dma_release_channel(dac->dma.chan);
    dac->dma.chan = NULL;
    snd_card_set_dev(card, NULL);
    iounmap(dac->regs);
    free_irq(dac->irq, dac);
    snd_card_free(card);

    platform_set_drvdata(pdev, NULL);

    return 0;
}

static struct platform_driver atmel_abdac_driver = {
    .remove     = __devexit_p(atmel_abdac_remove),
    .driver     = {
        .name   = "atmel_abdac",
        .owner  = THIS_MODULE,
        .pm = ATMEL_ABDAC_PM_OPS,
    },
};

static int __init atmel_abdac_init(void)
{
    return platform_driver_probe(&atmel_abdac_driver,
            atmel_abdac_probe);
}
module_init(atmel_abdac_init);

static void __exit atmel_abdac_exit(void)
{
    platform_driver_unregister(&atmel_abdac_driver);
}
module_exit(atmel_abdac_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Driver for Atmel Audio Bitstream DAC (ABDAC)");
MODULE_AUTHOR("Hans-Christian Egtvedt <[email protected]>");