davinci-pcm.c

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/*
 * ALSA PCM interface for the TI DAVINCI processor
 *
 * Author:      Vladimir Barinov, <[email protected]>
 * Copyright:   (C) 2007 MontaVista Software, Inc., <[email protected]>
 * added SRAM ping/pong (C) 2008 Troy Kisky <[email protected]>
 *
 * 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/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include <linux/kernel.h>

#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/soc.h>

#include <asm/dma.h>
#include <mach/sram.h>

#include "davinci-pcm.h"

#ifdef DEBUG
static void print_buf_info(int slot, char *name)
{
    struct edmacc_param p;
    if (slot < 0)
        return;
    edma_read_slot(slot, &p);
    printk(KERN_DEBUG "%s: 0x%x, opt=%x, src=%x, a_b_cnt=%x dst=%x\n",
            name, slot, p.opt, p.src, p.a_b_cnt, p.dst);
    printk(KERN_DEBUG "    src_dst_bidx=%x link_bcntrld=%x src_dst_cidx=%x ccnt=%x\n",
            p.src_dst_bidx, p.link_bcntrld, p.src_dst_cidx, p.ccnt);
}
#else
static void print_buf_info(int slot, char *name)
{
}
#endif

#define DAVINCI_PCM_FMTBITS (\
                SNDRV_PCM_FMTBIT_S8 |\
                SNDRV_PCM_FMTBIT_U8 |\
                SNDRV_PCM_FMTBIT_S16_LE |\
                SNDRV_PCM_FMTBIT_S16_BE |\
                SNDRV_PCM_FMTBIT_U16_LE |\
                SNDRV_PCM_FMTBIT_U16_BE |\
                SNDRV_PCM_FMTBIT_S24_LE |\
                SNDRV_PCM_FMTBIT_S24_BE |\
                SNDRV_PCM_FMTBIT_U24_LE |\
                SNDRV_PCM_FMTBIT_U24_BE |\
                SNDRV_PCM_FMTBIT_S32_LE |\
                SNDRV_PCM_FMTBIT_S32_BE |\
                SNDRV_PCM_FMTBIT_U32_LE |\
                SNDRV_PCM_FMTBIT_U32_BE)

static struct snd_pcm_hardware pcm_hardware_playback = {
    .info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER |
         SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
         SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME|
         SNDRV_PCM_INFO_BATCH),
    .formats = DAVINCI_PCM_FMTBITS,
    .rates = (SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 |
          SNDRV_PCM_RATE_22050 | SNDRV_PCM_RATE_32000 |
          SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000 |
          SNDRV_PCM_RATE_88200 | SNDRV_PCM_RATE_96000 |
          SNDRV_PCM_RATE_KNOT),
    .rate_min = 8000,
    .rate_max = 96000,
    .channels_min = 2,
    .channels_max = 384,
    .buffer_bytes_max = 128 * 1024,
    .period_bytes_min = 32,
    .period_bytes_max = 8 * 1024,
    .periods_min = 16,
    .periods_max = 255,
    .fifo_size = 0,
};

static struct snd_pcm_hardware pcm_hardware_capture = {
    .info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER |
         SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
         SNDRV_PCM_INFO_PAUSE |
         SNDRV_PCM_INFO_BATCH),
    .formats = DAVINCI_PCM_FMTBITS,
    .rates = (SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 |
          SNDRV_PCM_RATE_22050 | SNDRV_PCM_RATE_32000 |
          SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000 |
          SNDRV_PCM_RATE_88200 | SNDRV_PCM_RATE_96000 |
          SNDRV_PCM_RATE_KNOT),
    .rate_min = 8000,
    .rate_max = 96000,
    .channels_min = 2,
    .channels_max = 384,
    .buffer_bytes_max = 128 * 1024,
    .period_bytes_min = 32,
    .period_bytes_max = 8 * 1024,
    .periods_min = 16,
    .periods_max = 255,
    .fifo_size = 0,
};

/*
 * How ping/pong works....
 *
 * Playback:
 * ram_params - copys 2*ping_size from start of SDRAM to iram,
 *  links to ram_link2
 * ram_link2 - copys rest of SDRAM to iram in ping_size units,
 *  links to ram_link
 * ram_link - copys entire SDRAM to iram in ping_size uints,
 *  links to self
 *
 * asp_params - same as asp_link[0]
 * asp_link[0] - copys from lower half of iram to asp port
 *  links to asp_link[1], triggers iram copy event on completion
 * asp_link[1] - copys from upper half of iram to asp port
 *  links to asp_link[0], triggers iram copy event on completion
 *  triggers interrupt only needed to let upper SOC levels update position
 *  in stream on completion
 *
 * When playback is started:
 *  ram_params started
 *  asp_params started
 *
 * Capture:
 * ram_params - same as ram_link,
 *  links to ram_link
 * ram_link - same as playback
 *  links to self
 *
 * asp_params - same as playback
 * asp_link[0] - same as playback
 * asp_link[1] - same as playback
 *
 * When capture is started:
 *  asp_params started
 */
struct davinci_runtime_data {
    spinlock_t lock;
    int period;     /* current DMA period */
    int asp_channel;    /* Master DMA channel */
    int asp_link[2];    /* asp parameter link channel, ping/pong */
    struct davinci_pcm_dma_params *params;  /* DMA params */
    int ram_channel;
    int ram_link;
    int ram_link2;
    struct edmacc_param asp_params;
    struct edmacc_param ram_params;
};

static void davinci_pcm_period_elapsed(struct snd_pcm_substream *substream)
{
    struct davinci_runtime_data *prtd = substream->runtime->private_data;
    struct snd_pcm_runtime *runtime = substream->runtime;

    prtd->period++;
    if (unlikely(prtd->period >= runtime->periods))
        prtd->period = 0;
}

static void davinci_pcm_period_reset(struct snd_pcm_substream *substream)
{
    struct davinci_runtime_data *prtd = substream->runtime->private_data;

    prtd->period = 0;
}
/*
 * Not used with ping/pong
 */
static void davinci_pcm_enqueue_dma(struct snd_pcm_substream *substream)
{
    struct davinci_runtime_data *prtd = substream->runtime->private_data;
    struct snd_pcm_runtime *runtime = substream->runtime;
    unsigned int period_size;
    unsigned int dma_offset;
    dma_addr_t dma_pos;
    dma_addr_t src, dst;
    unsigned short src_bidx, dst_bidx;
    unsigned short src_cidx, dst_cidx;
    unsigned int data_type;
    unsigned short acnt;
    unsigned int count;
    unsigned int fifo_level;

    period_size = snd_pcm_lib_period_bytes(substream);
    dma_offset = prtd->period * period_size;
    dma_pos = runtime->dma_addr + dma_offset;
    fifo_level = prtd->params->fifo_level;

    pr_debug("davinci_pcm: audio_set_dma_params_play channel = %d "
        "dma_ptr = %x period_size=%x\n", prtd->asp_link[0], dma_pos,
        period_size);

    data_type = prtd->params->data_type;
    count = period_size / data_type;
    if (fifo_level)
        count /= fifo_level;

    if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
        src = dma_pos;
        dst = prtd->params->dma_addr;
        src_bidx = data_type;
        dst_bidx = 0;
        src_cidx = data_type * fifo_level;
        dst_cidx = 0;
    } else {
        src = prtd->params->dma_addr;
        dst = dma_pos;
        src_bidx = 0;
        dst_bidx = data_type;
        src_cidx = 0;
        dst_cidx = data_type * fifo_level;
    }

    acnt = prtd->params->acnt;
    edma_set_src(prtd->asp_link[0], src, INCR, W8BIT);
    edma_set_dest(prtd->asp_link[0], dst, INCR, W8BIT);

    edma_set_src_index(prtd->asp_link[0], src_bidx, src_cidx);
    edma_set_dest_index(prtd->asp_link[0], dst_bidx, dst_cidx);

    if (!fifo_level)
        edma_set_transfer_params(prtd->asp_link[0], acnt, count, 1, 0,
                            ASYNC);
    else
        edma_set_transfer_params(prtd->asp_link[0], acnt, fifo_level,
                            count, fifo_level,
                            ABSYNC);
}

static void davinci_pcm_dma_irq(unsigned link, u16 ch_status, void *data)
{
    struct snd_pcm_substream *substream = data;
    struct davinci_runtime_data *prtd = substream->runtime->private_data;

    print_buf_info(prtd->ram_channel, "i ram_channel");
    pr_debug("davinci_pcm: link=%d, status=0x%x\n", link, ch_status);

    if (unlikely(ch_status != DMA_COMPLETE))
        return;

    if (snd_pcm_running(substream)) {
        spin_lock(&prtd->lock);
        if (prtd->ram_channel < 0) {
            /* No ping/pong must fix up link dma data*/
            davinci_pcm_enqueue_dma(substream);
        }
        davinci_pcm_period_elapsed(substream);
        spin_unlock(&prtd->lock);
        snd_pcm_period_elapsed(substream);
    }
}

static int allocate_sram(struct snd_pcm_substream *substream, unsigned size,
        struct snd_pcm_hardware *ppcm)
{
    struct snd_dma_buffer *buf = &substream->dma_buffer;
    struct snd_dma_buffer *iram_dma = NULL;
    dma_addr_t iram_phys = 0;
    void *iram_virt = NULL;

    if (buf->private_data || !size)
        return 0;

    ppcm->period_bytes_max = size;
    iram_virt = sram_alloc(size, &iram_phys);
    if (!iram_virt)
        goto exit1;
    iram_dma = kzalloc(sizeof(*iram_dma), GFP_KERNEL);
    if (!iram_dma)
        goto exit2;
    iram_dma->area = iram_virt;
    iram_dma->addr = iram_phys;
    memset(iram_dma->area, 0, size);
    iram_dma->bytes = size;
    buf->private_data = iram_dma;
    return 0;
exit2:
    if (iram_virt)
        sram_free(iram_virt, size);
exit1:
    return -ENOMEM;
}

/*
 * Only used with ping/pong.
 * This is called after runtime->dma_addr, period_bytes and data_type are valid
 */
static int ping_pong_dma_setup(struct snd_pcm_substream *substream)
{
    unsigned short ram_src_cidx, ram_dst_cidx;
    struct snd_pcm_runtime *runtime = substream->runtime;
    struct davinci_runtime_data *prtd = runtime->private_data;
    struct snd_dma_buffer *iram_dma =
        (struct snd_dma_buffer *)substream->dma_buffer.private_data;
    struct davinci_pcm_dma_params *params = prtd->params;
    unsigned int data_type = params->data_type;
    unsigned int acnt = params->acnt;
    /* divide by 2 for ping/pong */
    unsigned int ping_size = snd_pcm_lib_period_bytes(substream) >> 1;
    unsigned int fifo_level = prtd->params->fifo_level;
    unsigned int count;
    if ((data_type == 0) || (data_type > 4)) {
        printk(KERN_ERR "%s: data_type=%i\n", __func__, data_type);
        return -EINVAL;
    }
    if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
        dma_addr_t asp_src_pong = iram_dma->addr + ping_size;
        ram_src_cidx = ping_size;
        ram_dst_cidx = -ping_size;
        edma_set_src(prtd->asp_link[1], asp_src_pong, INCR, W8BIT);

        edma_set_src_index(prtd->asp_link[0], data_type,
                data_type * fifo_level);
        edma_set_src_index(prtd->asp_link[1], data_type,
                data_type * fifo_level);

        edma_set_src(prtd->ram_link, runtime->dma_addr, INCR, W32BIT);
    } else {
        dma_addr_t asp_dst_pong = iram_dma->addr + ping_size;
        ram_src_cidx = -ping_size;
        ram_dst_cidx = ping_size;
        edma_set_dest(prtd->asp_link[1], asp_dst_pong, INCR, W8BIT);

        edma_set_dest_index(prtd->asp_link[0], data_type,
                data_type * fifo_level);
        edma_set_dest_index(prtd->asp_link[1], data_type,
                data_type * fifo_level);

        edma_set_dest(prtd->ram_link, runtime->dma_addr, INCR, W32BIT);
    }

    if (!fifo_level) {
        count = ping_size / data_type;
        edma_set_transfer_params(prtd->asp_link[0], acnt, count,
                1, 0, ASYNC);
        edma_set_transfer_params(prtd->asp_link[1], acnt, count,
                1, 0, ASYNC);
    } else {
        count = ping_size / (data_type * fifo_level);
        edma_set_transfer_params(prtd->asp_link[0], acnt, fifo_level,
                count, fifo_level, ABSYNC);
        edma_set_transfer_params(prtd->asp_link[1], acnt, fifo_level,
                count, fifo_level, ABSYNC);
    }

    edma_set_src_index(prtd->ram_link, ping_size, ram_src_cidx);
    edma_set_dest_index(prtd->ram_link, ping_size, ram_dst_cidx);
    edma_set_transfer_params(prtd->ram_link, ping_size, 2,
            runtime->periods, 2, ASYNC);

    /* init master params */
    edma_read_slot(prtd->asp_link[0], &prtd->asp_params);
    edma_read_slot(prtd->ram_link, &prtd->ram_params);
    if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
        struct edmacc_param p_ram;
        /* Copy entire iram buffer before playback started */
        prtd->ram_params.a_b_cnt = (1 << 16) | (ping_size << 1);
        /* 0 dst_bidx */
        prtd->ram_params.src_dst_bidx = (ping_size << 1);
        /* 0 dst_cidx */
        prtd->ram_params.src_dst_cidx = (ping_size << 1);
        prtd->ram_params.ccnt = 1;

        /* Skip 1st period */
        edma_read_slot(prtd->ram_link, &p_ram);
        p_ram.src += (ping_size << 1);
        p_ram.ccnt -= 1;
        edma_write_slot(prtd->ram_link2, &p_ram);
        /*
         * When 1st started, ram -> iram dma channel will fill the
         * entire iram.  Then, whenever a ping/pong asp buffer finishes,
         * 1/2 iram will be filled.
         */
        prtd->ram_params.link_bcntrld =
            EDMA_CHAN_SLOT(prtd->ram_link2) << 5;
    }
    return 0;
}

/* 1 asp tx or rx channel using 2 parameter channels
 * 1 ram to/from iram channel using 1 parameter channel
 *
 * Playback
 * ram copy channel kicks off first,
 * 1st ram copy of entire iram buffer completion kicks off asp channel
 * asp tcc always kicks off ram copy of 1/2 iram buffer
 *
 * Record
 * asp channel starts, tcc kicks off ram copy
 */
static int request_ping_pong(struct snd_pcm_substream *substream,
        struct davinci_runtime_data *prtd,
        struct snd_dma_buffer *iram_dma)
{
    dma_addr_t asp_src_ping;
    dma_addr_t asp_dst_ping;
    int ret;
    struct davinci_pcm_dma_params *params = prtd->params;

    /* Request ram master channel */
    ret = prtd->ram_channel = edma_alloc_channel(EDMA_CHANNEL_ANY,
                  davinci_pcm_dma_irq, substream,
                  prtd->params->ram_chan_q);
    if (ret < 0)
        goto exit1;

    /* Request ram link channel */
    ret = prtd->ram_link = edma_alloc_slot(
            EDMA_CTLR(prtd->ram_channel), EDMA_SLOT_ANY);
    if (ret < 0)
        goto exit2;

    ret = prtd->asp_link[1] = edma_alloc_slot(
            EDMA_CTLR(prtd->asp_channel), EDMA_SLOT_ANY);
    if (ret < 0)
        goto exit3;

    prtd->ram_link2 = -1;
    if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
        ret = prtd->ram_link2 = edma_alloc_slot(
            EDMA_CTLR(prtd->ram_channel), EDMA_SLOT_ANY);
        if (ret < 0)
            goto exit4;
    }
    /* circle ping-pong buffers */
    edma_link(prtd->asp_link[0], prtd->asp_link[1]);
    edma_link(prtd->asp_link[1], prtd->asp_link[0]);
    /* circle ram buffers */
    edma_link(prtd->ram_link, prtd->ram_link);

    if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
        asp_src_ping = iram_dma->addr;
        asp_dst_ping = params->dma_addr;    /* fifo */
    } else {
        asp_src_ping = params->dma_addr;    /* fifo */
        asp_dst_ping = iram_dma->addr;
    }
    /* ping */
    edma_set_src(prtd->asp_link[0], asp_src_ping, INCR, W16BIT);
    edma_set_dest(prtd->asp_link[0], asp_dst_ping, INCR, W16BIT);
    edma_set_src_index(prtd->asp_link[0], 0, 0);
    edma_set_dest_index(prtd->asp_link[0], 0, 0);

    edma_read_slot(prtd->asp_link[0], &prtd->asp_params);
    prtd->asp_params.opt &= ~(TCCMODE | EDMA_TCC(0x3f) | TCINTEN);
    prtd->asp_params.opt |= TCCHEN |
        EDMA_TCC(prtd->ram_channel & 0x3f);
    edma_write_slot(prtd->asp_link[0], &prtd->asp_params);

    /* pong */
    edma_set_src(prtd->asp_link[1], asp_src_ping, INCR, W16BIT);
    edma_set_dest(prtd->asp_link[1], asp_dst_ping, INCR, W16BIT);
    edma_set_src_index(prtd->asp_link[1], 0, 0);
    edma_set_dest_index(prtd->asp_link[1], 0, 0);

    edma_read_slot(prtd->asp_link[1], &prtd->asp_params);
    prtd->asp_params.opt &= ~(TCCMODE | EDMA_TCC(0x3f));
    /* interrupt after every pong completion */
    prtd->asp_params.opt |= TCINTEN | TCCHEN |
        EDMA_TCC(prtd->ram_channel & 0x3f);
    edma_write_slot(prtd->asp_link[1], &prtd->asp_params);

    /* ram */
    edma_set_src(prtd->ram_link, iram_dma->addr, INCR, W32BIT);
    edma_set_dest(prtd->ram_link, iram_dma->addr, INCR, W32BIT);
    pr_debug("%s: audio dma channels/slots in use for ram:%u %u %u,"
        "for asp:%u %u %u\n", __func__,
        prtd->ram_channel, prtd->ram_link, prtd->ram_link2,
        prtd->asp_channel, prtd->asp_link[0],
        prtd->asp_link[1]);
    return 0;
exit4:
    edma_free_channel(prtd->asp_link[1]);
    prtd->asp_link[1] = -1;
exit3:
    edma_free_channel(prtd->ram_link);
    prtd->ram_link = -1;
exit2:
    edma_free_channel(prtd->ram_channel);
    prtd->ram_channel = -1;
exit1:
    return ret;
}

static int davinci_pcm_dma_request(struct snd_pcm_substream *substream)
{
    struct snd_dma_buffer *iram_dma;
    struct davinci_runtime_data *prtd = substream->runtime->private_data;
    struct davinci_pcm_dma_params *params = prtd->params;
    int ret;

    if (!params)
        return -ENODEV;

    /* Request asp master DMA channel */
    ret = prtd->asp_channel = edma_alloc_channel(params->channel,
            davinci_pcm_dma_irq, substream,
            prtd->params->asp_chan_q);
    if (ret < 0)
        goto exit1;

    /* Request asp link channels */
    ret = prtd->asp_link[0] = edma_alloc_slot(
            EDMA_CTLR(prtd->asp_channel), EDMA_SLOT_ANY);
    if (ret < 0)
        goto exit2;

    iram_dma = (struct snd_dma_buffer *)substream->dma_buffer.private_data;
    if (iram_dma) {
        if (request_ping_pong(substream, prtd, iram_dma) == 0)
            return 0;
        printk(KERN_WARNING "%s: dma channel allocation failed,"
                "not using sram\n", __func__);
    }

    /* Issue transfer completion IRQ when the channel completes a
     * transfer, then always reload from the same slot (by a kind
     * of loopback link).  The completion IRQ handler will update
     * the reload slot with a new buffer.
     *
     * REVISIT save p_ram here after setting up everything except
     * the buffer and its length (ccnt) ... use it as a template
     * so davinci_pcm_enqueue_dma() takes less time in IRQ.
     */
    edma_read_slot(prtd->asp_link[0], &prtd->asp_params);
    prtd->asp_params.opt |= TCINTEN |
        EDMA_TCC(EDMA_CHAN_SLOT(prtd->asp_channel));
    prtd->asp_params.link_bcntrld = EDMA_CHAN_SLOT(prtd->asp_link[0]) << 5;
    edma_write_slot(prtd->asp_link[0], &prtd->asp_params);
    return 0;
exit2:
    edma_free_channel(prtd->asp_channel);
    prtd->asp_channel = -1;
exit1:
    return ret;
}

static int davinci_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
    struct davinci_runtime_data *prtd = substream->runtime->private_data;
    int ret = 0;

    spin_lock(&prtd->lock);

    switch (cmd) {
    case SNDRV_PCM_TRIGGER_START:
        edma_start(prtd->asp_channel);
        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
            prtd->ram_channel >= 0) {
            /* copy 1st iram buffer */
            edma_start(prtd->ram_channel);
        }
        break;
    case SNDRV_PCM_TRIGGER_RESUME:
    case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
        edma_resume(prtd->asp_channel);
        break;
    case SNDRV_PCM_TRIGGER_STOP:
    case SNDRV_PCM_TRIGGER_SUSPEND:
    case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
        edma_pause(prtd->asp_channel);
        break;
    default:
        ret = -EINVAL;
        break;
    }

    spin_unlock(&prtd->lock);

    return ret;
}

static int davinci_pcm_prepare(struct snd_pcm_substream *substream)
{
    struct davinci_runtime_data *prtd = substream->runtime->private_data;

    davinci_pcm_period_reset(substream);
    if (prtd->ram_channel >= 0) {
        int ret = ping_pong_dma_setup(substream);
        if (ret < 0)
            return ret;

        edma_write_slot(prtd->ram_channel, &prtd->ram_params);
        edma_write_slot(prtd->asp_channel, &prtd->asp_params);

        print_buf_info(prtd->ram_channel, "ram_channel");
        print_buf_info(prtd->ram_link, "ram_link");
        print_buf_info(prtd->ram_link2, "ram_link2");
        print_buf_info(prtd->asp_channel, "asp_channel");
        print_buf_info(prtd->asp_link[0], "asp_link[0]");
        print_buf_info(prtd->asp_link[1], "asp_link[1]");

        /*
         * There is a phase offset of 2 periods between the position
         * used by dma setup and the position reported in the pointer
         * function.
         *
         * The phase offset, when not using ping-pong buffers, is due to
         * the two consecutive calls to davinci_pcm_enqueue_dma() below.
         *
         * Whereas here, with ping-pong buffers, the phase is due to
         * there being an entire buffer transfer complete before the
         * first dma completion event triggers davinci_pcm_dma_irq().
         */
        davinci_pcm_period_elapsed(substream);
        davinci_pcm_period_elapsed(substream);

        return 0;
    }
    davinci_pcm_enqueue_dma(substream);
    davinci_pcm_period_elapsed(substream);

    /* Copy self-linked parameter RAM entry into master channel */
    edma_read_slot(prtd->asp_link[0], &prtd->asp_params);
    edma_write_slot(prtd->asp_channel, &prtd->asp_params);
    davinci_pcm_enqueue_dma(substream);
    davinci_pcm_period_elapsed(substream);

    return 0;
}

static snd_pcm_uframes_t
davinci_pcm_pointer(struct snd_pcm_substream *substream)
{
    struct snd_pcm_runtime *runtime = substream->runtime;
    struct davinci_runtime_data *prtd = runtime->private_data;
    unsigned int offset;
    int asp_count;
    unsigned int period_size = snd_pcm_lib_period_bytes(substream);

    /*
     * There is a phase offset of 2 periods between the position used by dma
     * setup and the position reported in the pointer function. Either +2 in
     * the dma setup or -2 here in the pointer function (with wrapping,
     * both) accounts for this offset -- choose the latter since it makes
     * the first-time setup clearer.
     */
    spin_lock(&prtd->lock);
    asp_count = prtd->period - 2;
    spin_unlock(&prtd->lock);

    if (asp_count < 0)
        asp_count += runtime->periods;
    asp_count *= period_size;

    offset = bytes_to_frames(runtime, asp_count);
    if (offset >= runtime->buffer_size)
        offset = 0;

    return offset;
}

static int davinci_pcm_open(struct snd_pcm_substream *substream)
{
    struct snd_pcm_runtime *runtime = substream->runtime;
    struct davinci_runtime_data *prtd;
    struct snd_pcm_hardware *ppcm;
    int ret = 0;
    struct snd_soc_pcm_runtime *rtd = substream->private_data;
    struct davinci_pcm_dma_params *pa;
    struct davinci_pcm_dma_params *params;

    pa = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
    if (!pa)
        return -ENODEV;
    params = &pa[substream->stream];

    ppcm = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) ?
            &pcm_hardware_playback : &pcm_hardware_capture;
    allocate_sram(substream, params->sram_size, ppcm);
    snd_soc_set_runtime_hwparams(substream, ppcm);
    /* ensure that buffer size is a multiple of period size */
    ret = snd_pcm_hw_constraint_integer(runtime,
                        SNDRV_PCM_HW_PARAM_PERIODS);
    if (ret < 0)
        return ret;

    prtd = kzalloc(sizeof(struct davinci_runtime_data), GFP_KERNEL);
    if (prtd == NULL)
        return -ENOMEM;

    spin_lock_init(&prtd->lock);
    prtd->params = params;
    prtd->asp_channel = -1;
    prtd->asp_link[0] = prtd->asp_link[1] = -1;
    prtd->ram_channel = -1;
    prtd->ram_link = -1;
    prtd->ram_link2 = -1;

    runtime->private_data = prtd;

    ret = davinci_pcm_dma_request(substream);
    if (ret) {
        printk(KERN_ERR "davinci_pcm: Failed to get dma channels\n");
        kfree(prtd);
    }

    return ret;
}

static int davinci_pcm_close(struct snd_pcm_substream *substream)
{
    struct snd_pcm_runtime *runtime = substream->runtime;
    struct davinci_runtime_data *prtd = runtime->private_data;

    if (prtd->ram_channel >= 0)
        edma_stop(prtd->ram_channel);
    if (prtd->asp_channel >= 0)
        edma_stop(prtd->asp_channel);
    if (prtd->asp_link[0] >= 0)
        edma_unlink(prtd->asp_link[0]);
    if (prtd->asp_link[1] >= 0)
        edma_unlink(prtd->asp_link[1]);
    if (prtd->ram_link >= 0)
        edma_unlink(prtd->ram_link);

    if (prtd->asp_link[0] >= 0)
        edma_free_slot(prtd->asp_link[0]);
    if (prtd->asp_link[1] >= 0)
        edma_free_slot(prtd->asp_link[1]);
    if (prtd->asp_channel >= 0)
        edma_free_channel(prtd->asp_channel);
    if (prtd->ram_link >= 0)
        edma_free_slot(prtd->ram_link);
    if (prtd->ram_link2 >= 0)
        edma_free_slot(prtd->ram_link2);
    if (prtd->ram_channel >= 0)
        edma_free_channel(prtd->ram_channel);

    kfree(prtd);

    return 0;
}

static int davinci_pcm_hw_params(struct snd_pcm_substream *substream,
                 struct snd_pcm_hw_params *hw_params)
{
    return snd_pcm_lib_malloc_pages(substream,
                    params_buffer_bytes(hw_params));
}

static int davinci_pcm_hw_free(struct snd_pcm_substream *substream)
{
    return snd_pcm_lib_free_pages(substream);
}

static int davinci_pcm_mmap(struct snd_pcm_substream *substream,
                struct vm_area_struct *vma)
{
    struct snd_pcm_runtime *runtime = substream->runtime;

    return dma_mmap_writecombine(substream->pcm->card->dev, vma,
                     runtime->dma_area,
                     runtime->dma_addr,
                     runtime->dma_bytes);
}

static struct snd_pcm_ops davinci_pcm_ops = {
    .open =     davinci_pcm_open,
    .close =    davinci_pcm_close,
    .ioctl =    snd_pcm_lib_ioctl,
    .hw_params =    davinci_pcm_hw_params,
    .hw_free =  davinci_pcm_hw_free,
    .prepare =  davinci_pcm_prepare,
    .trigger =  davinci_pcm_trigger,
    .pointer =  davinci_pcm_pointer,
    .mmap =     davinci_pcm_mmap,
};

static int davinci_pcm_preallocate_dma_buffer(struct snd_pcm *pcm, int stream,
        size_t size)
{
    struct snd_pcm_substream *substream = pcm->streams[stream].substream;
    struct snd_dma_buffer *buf = &substream->dma_buffer;

    buf->dev.type = SNDRV_DMA_TYPE_DEV;
    buf->dev.dev = pcm->card->dev;
    buf->private_data = NULL;
    buf->area = dma_alloc_writecombine(pcm->card->dev, size,
                       &buf->addr, GFP_KERNEL);

    pr_debug("davinci_pcm: preallocate_dma_buffer: area=%p, addr=%p, "
        "size=%d\n", (void *) buf->area, (void *) buf->addr, size);

    if (!buf->area)
        return -ENOMEM;

    buf->bytes = size;
    return 0;
}

static void davinci_pcm_free(struct snd_pcm *pcm)
{
    struct snd_pcm_substream *substream;
    struct snd_dma_buffer *buf;
    int stream;

    for (stream = 0; stream < 2; stream++) {
        struct snd_dma_buffer *iram_dma;
        substream = pcm->streams[stream].substream;
        if (!substream)
            continue;

        buf = &substream->dma_buffer;
        if (!buf->area)
            continue;

        dma_free_writecombine(pcm->card->dev, buf->bytes,
                      buf->area, buf->addr);
        buf->area = NULL;
        iram_dma = buf->private_data;
        if (iram_dma) {
            sram_free(iram_dma->area, iram_dma->bytes);
            kfree(iram_dma);
        }
    }
}

static u64 davinci_pcm_dmamask = DMA_BIT_MASK(32);

static int davinci_pcm_new(struct snd_soc_pcm_runtime *rtd)
{
    struct snd_card *card = rtd->card->snd_card;
    struct snd_pcm *pcm = rtd->pcm;
    int ret;

    if (!card->dev->dma_mask)
        card->dev->dma_mask = &davinci_pcm_dmamask;
    if (!card->dev->coherent_dma_mask)
        card->dev->coherent_dma_mask = DMA_BIT_MASK(32);

    if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream) {
        ret = davinci_pcm_preallocate_dma_buffer(pcm,
            SNDRV_PCM_STREAM_PLAYBACK,
            pcm_hardware_playback.buffer_bytes_max);
        if (ret)
            return ret;
    }

    if (pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream) {
        ret = davinci_pcm_preallocate_dma_buffer(pcm,
            SNDRV_PCM_STREAM_CAPTURE,
            pcm_hardware_capture.buffer_bytes_max);
        if (ret)
            return ret;
    }

    return 0;
}

static struct snd_soc_platform_driver davinci_soc_platform = {
    .ops =      &davinci_pcm_ops,
    .pcm_new =  davinci_pcm_new,
    .pcm_free =     davinci_pcm_free,
};

int davinci_soc_platform_register(struct device *dev)
{
    return snd_soc_register_platform(dev, &davinci_soc_platform);
}
EXPORT_SYMBOL_GPL(davinci_soc_platform_register);

void davinci_soc_platform_unregister(struct device *dev)
{
    snd_soc_unregister_platform(dev);
}
EXPORT_SYMBOL_GPL(davinci_soc_platform_unregister);

MODULE_AUTHOR("Vladimir Barinov");
MODULE_DESCRIPTION("TI DAVINCI PCM DMA module");
MODULE_LICENSE("GPL");