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dma-sh7760.c

/*
 * SH7760 ("camelot") DMABRG audio DMA unit support
 *
 * 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.
 *
 * The SH7760 DMABRG provides 4 dma channels (2x rec, 2x play), which
 * trigger an interrupt when one half of the programmed transfer size
 * has been xmitted.
 *
 * FIXME: little-endian only for now
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/soc.h>
#include <asm/dmabrg.h>


/* registers and bits */
#define BRGATXSAR 0x00
#define BRGARXDAR 0x04
#define BRGATXTCR 0x08
#define BRGARXTCR 0x0C
#define BRGACR          0x10
#define BRGATXTCNT      0x14
#define BRGARXTCNT      0x18

#define ACR_RAR         (1 << 18)
#define ACR_RDS         (1 << 17)
#define ACR_RDE         (1 << 16)
#define ACR_TAR         (1 << 2)
#define ACR_TDS         (1 << 1)
#define ACR_TDE         (1 << 0)

/* receiver/transmitter data alignment */
#define ACR_RAM_NONE    (0 << 24)
#define ACR_RAM_4BYTE   (1 << 24)
#define ACR_RAM_2WORD   (2 << 24)
#define ACR_TAM_NONE    (0 << 8)
#define ACR_TAM_4BYTE   (1 << 8)
#define ACR_TAM_2WORD   (2 << 8)


struct camelot_pcm {
      unsigned long mmio;  /* DMABRG audio channel control reg MMIO */
      unsigned int txid;    /* ID of first DMABRG IRQ for this unit */

      struct snd_pcm_substream *tx_ss;
      unsigned long tx_period_size;
      unsigned int  tx_period;

      struct snd_pcm_substream *rx_ss;
      unsigned long rx_period_size;
      unsigned int  rx_period;

} cam_pcm_data[2] = {
      {
            .mmio =     0xFE3C0040,
            .txid =     DMABRGIRQ_A0TXF,
      },
      {
            .mmio =     0xFE3C0060,
            .txid =     DMABRGIRQ_A1TXF,
      },
};

#define BRGREG(x) (*(unsigned long *)(cam->mmio + (x)))

/*
 * set a minimum of 16kb per period, to avoid interrupt-"storm" and
 * resulting skipping. In general, the bigger the minimum size, the
 * better for overall system performance. (The SH7760 is a puny CPU
 * with a slow SDRAM interface and poor internal bus bandwidth,
 * *especially* when the LCDC is active).  The minimum for the DMAC
 * is 8 bytes; 16kbytes are enough to get skip-free playback of a
 * 44kHz/16bit/stereo MP3 on a lightly loaded system, and maintain
 * reasonable responsiveness in MPlayer.
 */
#define DMABRG_PERIOD_MIN           16 * 1024
#define DMABRG_PERIOD_MAX           0x03fffffc
#define DMABRG_PREALLOC_BUFFER            32 * 1024
#define DMABRG_PREALLOC_BUFFER_MAX  32 * 1024

/* support everything the SSI supports */
#define DMABRG_RATES    \
      SNDRV_PCM_RATE_8000_192000

#define DMABRG_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_pcm_hardware camelot_pcm_hardware = {
      .info = (SNDRV_PCM_INFO_MMAP |
            SNDRV_PCM_INFO_INTERLEAVED |
            SNDRV_PCM_INFO_BLOCK_TRANSFER |
            SNDRV_PCM_INFO_MMAP_VALID),
      .formats =  DMABRG_FMTS,
      .rates =    DMABRG_RATES,
      .rate_min =       8000,
      .rate_max =       192000,
      .channels_min =         2,
      .channels_max =         8,          /* max of the SSI */
      .buffer_bytes_max =     DMABRG_PERIOD_MAX,
      .period_bytes_min =     DMABRG_PERIOD_MIN,
      .period_bytes_max =     DMABRG_PERIOD_MAX / 2,
      .periods_min =          2,
      .periods_max =          2,
      .fifo_size =            128,
};

static void camelot_txdma(void *data)
{
      struct camelot_pcm *cam = data;
      cam->tx_period ^= 1;
      snd_pcm_period_elapsed(cam->tx_ss);
}

static void camelot_rxdma(void *data)
{
      struct camelot_pcm *cam = data;
      cam->rx_period ^= 1;
      snd_pcm_period_elapsed(cam->rx_ss);
}

static int camelot_pcm_open(struct snd_pcm_substream *substream)
{
      struct snd_soc_pcm_runtime *rtd = substream->private_data;
      struct camelot_pcm *cam = &cam_pcm_data[rtd->dai->cpu_dai->id];
      int recv = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0:1;
      int ret, dmairq;

      snd_soc_set_runtime_hwparams(substream, &camelot_pcm_hardware);

      /* DMABRG buffer half/full events */
      dmairq = (recv) ? cam->txid + 2 : cam->txid;
      if (recv) {
            cam->rx_ss = substream;
            ret = dmabrg_request_irq(dmairq, camelot_rxdma, cam);
            if (unlikely(ret)) {
                  pr_debug("audio unit %d irqs already taken!\n",
                       rtd->dai->cpu_dai->id);
                  return -EBUSY;
            }
            (void)dmabrg_request_irq(dmairq + 1,camelot_rxdma, cam);
      } else {
            cam->tx_ss = substream;
            ret = dmabrg_request_irq(dmairq, camelot_txdma, cam);
            if (unlikely(ret)) {
                  pr_debug("audio unit %d irqs already taken!\n",
                       rtd->dai->cpu_dai->id);
                  return -EBUSY;
            }
            (void)dmabrg_request_irq(dmairq + 1, camelot_txdma, cam);
      }
      return 0;
}

static int camelot_pcm_close(struct snd_pcm_substream *substream)
{
      struct snd_soc_pcm_runtime *rtd = substream->private_data;
      struct camelot_pcm *cam = &cam_pcm_data[rtd->dai->cpu_dai->id];
      int recv = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0:1;
      int dmairq;

      dmairq = (recv) ? cam->txid + 2 : cam->txid;

      if (recv)
            cam->rx_ss = NULL;
      else
            cam->tx_ss = NULL;

      dmabrg_free_irq(dmairq + 1);
      dmabrg_free_irq(dmairq);

      return 0;
}

static int camelot_hw_params(struct snd_pcm_substream *substream,
                       struct snd_pcm_hw_params *hw_params)
{
      struct snd_soc_pcm_runtime *rtd = substream->private_data;
      struct camelot_pcm *cam = &cam_pcm_data[rtd->dai->cpu_dai->id];
      int recv = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0:1;
      int ret;

      ret = snd_pcm_lib_malloc_pages(substream,
                               params_buffer_bytes(hw_params));
      if (ret < 0)
            return ret;

      if (recv) {
            cam->rx_period_size = params_period_bytes(hw_params);
            cam->rx_period = 0;
      } else {
            cam->tx_period_size = params_period_bytes(hw_params);
            cam->tx_period = 0;
      }
      return 0;
}

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

static int camelot_prepare(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      struct snd_soc_pcm_runtime *rtd = substream->private_data;
      struct camelot_pcm *cam = &cam_pcm_data[rtd->dai->cpu_dai->id];

      pr_debug("PCM data: addr 0x%08ulx len %d\n",
             (u32)runtime->dma_addr, runtime->dma_bytes);
 
      if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
            BRGREG(BRGATXSAR) = (unsigned long)runtime->dma_area;
            BRGREG(BRGATXTCR) = runtime->dma_bytes;
      } else {
            BRGREG(BRGARXDAR) = (unsigned long)runtime->dma_area;
            BRGREG(BRGARXTCR) = runtime->dma_bytes;
      }

      return 0;
}

static inline void dmabrg_play_dma_start(struct camelot_pcm *cam)
{
      unsigned long acr = BRGREG(BRGACR) & ~(ACR_TDS | ACR_RDS);
      /* start DMABRG engine: XFER start, auto-addr-reload */
      BRGREG(BRGACR) = acr | ACR_TDE | ACR_TAR | ACR_TAM_2WORD;
}

static inline void dmabrg_play_dma_stop(struct camelot_pcm *cam)
{
      unsigned long acr = BRGREG(BRGACR) & ~(ACR_TDS | ACR_RDS);
      /* forcibly terminate data transmission */
      BRGREG(BRGACR) = acr | ACR_TDS;
}

static inline void dmabrg_rec_dma_start(struct camelot_pcm *cam)
{
      unsigned long acr = BRGREG(BRGACR) & ~(ACR_TDS | ACR_RDS);
      /* start DMABRG engine: recv start, auto-reload */
      BRGREG(BRGACR) = acr | ACR_RDE | ACR_RAR | ACR_RAM_2WORD;
}

static inline void dmabrg_rec_dma_stop(struct camelot_pcm *cam)
{
      unsigned long acr = BRGREG(BRGACR) & ~(ACR_TDS | ACR_RDS);
      /* forcibly terminate data receiver */
      BRGREG(BRGACR) = acr | ACR_RDS;
}

static int camelot_trigger(struct snd_pcm_substream *substream, int cmd)
{
      struct snd_soc_pcm_runtime *rtd = substream->private_data;
      struct camelot_pcm *cam = &cam_pcm_data[rtd->dai->cpu_dai->id];
      int recv = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0:1;

      switch (cmd) {
      case SNDRV_PCM_TRIGGER_START:
            if (recv)
                  dmabrg_rec_dma_start(cam);
            else
                  dmabrg_play_dma_start(cam);
            break;
      case SNDRV_PCM_TRIGGER_STOP:
            if (recv)
                  dmabrg_rec_dma_stop(cam);
            else
                  dmabrg_play_dma_stop(cam);
            break;
      default:
            return -EINVAL;
      }

      return 0;
}

static snd_pcm_uframes_t camelot_pos(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      struct snd_soc_pcm_runtime *rtd = substream->private_data;
      struct camelot_pcm *cam = &cam_pcm_data[rtd->dai->cpu_dai->id];
      int recv = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0:1;
      unsigned long pos;

      /* cannot use the DMABRG pointer register: under load, by the
       * time ALSA comes around to read the register, it is already
       * far ahead (or worse, already done with the fragment) of the
       * position at the time the IRQ was triggered, which results in
       * fast-playback sound in my test application (ScummVM)
       */
      if (recv)
            pos = cam->rx_period ? cam->rx_period_size : 0;
      else
            pos = cam->tx_period ? cam->tx_period_size : 0;

      return bytes_to_frames(runtime, pos);
}

static struct snd_pcm_ops camelot_pcm_ops = {
      .open       = camelot_pcm_open,
      .close            = camelot_pcm_close,
      .ioctl            = snd_pcm_lib_ioctl,
      .hw_params  = camelot_hw_params,
      .hw_free    = camelot_hw_free,
      .prepare    = camelot_prepare,
      .trigger    = camelot_trigger,
      .pointer    = camelot_pos,
};

static void camelot_pcm_free(struct snd_pcm *pcm)
{
      snd_pcm_lib_preallocate_free_for_all(pcm);
}

static int camelot_pcm_new(struct snd_card *card,
                     struct snd_soc_codec_dai *dai,
                     struct snd_pcm *pcm)
{
      /* dont use SNDRV_DMA_TYPE_DEV, since it will oops the SH kernel
       * in MMAP mode (i.e. aplay -M)
       */
      snd_pcm_lib_preallocate_pages_for_all(pcm,
            SNDRV_DMA_TYPE_CONTINUOUS,
            snd_dma_continuous_data(GFP_KERNEL),
            DMABRG_PREALLOC_BUFFER, DMABRG_PREALLOC_BUFFER_MAX);

      return 0;
}

struct snd_soc_platform sh7760_soc_platform = {
      .name       = "sh7760-pcm",
      .pcm_ops    = &camelot_pcm_ops,
      .pcm_new    = camelot_pcm_new,
      .pcm_free   = camelot_pcm_free,
};
EXPORT_SYMBOL_GPL(sh7760_soc_platform);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SH7760 Audio DMA (DMABRG) driver");
MODULE_AUTHOR("Manuel Lauss <mano@roarinelk.homelinux.net>");

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