[alsa-devel] Driver code with mpc5200 pointer problem.

26 Apr 2009


      Here's the code computing the mpc5200 dma pointer. Could you please
take a look at it and let me know what it is doing wrong.
/*
 * Freescale MPC5200 Audio DMA
 * ALSA SoC Platform driver
 *
 * Copyright (C) 2008 Secret Lab Technologies Ltd.
 */
#define DEBUG
#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/dma-mapping.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/initval.h>
#include <sound/soc.h>
#include <sound/soc-of-simple.h>
#include <sysdev/bestcomm/bestcomm.h>
#include <sysdev/bestcomm/gen_bd.h>
#include <asm/time.h>
#include <asm/mpc52xx.h>
#include <asm/mpc52xx_psc.h>
#include "mpc5200_dma.h"
MODULE_AUTHOR("Grant Likely grant.likely@secretlab.ca");
MODULE_DESCRIPTION("Freescale MPC5200 PSC in DMA mode ASoC Driver");
MODULE_LICENSE("GPL");
/*
 * Interrupt handlers
 */
static irqreturn_t psc_dma_status_irq(int irq, void *_psc_dma)
{
    struct psc_dma *psc_dma = _psc_dma;
    struct mpc52xx_psc __iomem *regs = psc_dma->psc_regs;
    u16 isr;
isr = in_be16(&regs->mpc52xx_psc_isr);
/* Playback underrun error */
    if (psc_dma->playback.active && (isr & MPC52xx_PSC_IMR_TXEMP))
    	psc_dma->stats.underrun_count++;
/* Capture overrun error */
    if (psc_dma->capture.active && (isr & MPC52xx_PSC_IMR_ORERR))
    	psc_dma->stats.overrun_count++;
out_8(&regs->command, 4 << 4);	/* reset the error status */
return IRQ_HANDLED;
}
/**
 * psc_dma_bcom_enqueue_next_buffer - Enqueue another audio buffer
 * @s: pointer to stream private data structure
 *
 * Enqueues another audio period buffer into the bestcomm queue.
 *
 * Note: The routine must only be called when there is space available in
 * the queue.  Otherwise the enqueue will fail and the audio ring buffer
 * will get out of sync
 */
static void psc_dma_bcom_enqueue_next_buffer(struct psc_dma_stream *s)
{
    struct bcom_bd *bd;
/* Prepare and enqueue the next buffer descriptor */
    bd = bcom_prepare_next_buffer(s->bcom_task);
    bd->status = s->period_bytes;
    bd->data[0] = s->period_next_pt;
    bcom_submit_next_buffer(s->bcom_task, NULL);
/* Update for next period */
    s->period_next_pt += s->period_bytes;
    if (s->period_next_pt >= s->period_end)
    	s->period_next_pt = s->period_start;
}
/* Bestcomm DMA irq handler */
static irqreturn_t psc_dma_bcom_irq(int irq, void *_psc_dma_stream)
{
    struct psc_dma_stream *s = _psc_dma_stream;
/* For each finished period, dequeue the completed period buffer
     * and enqueue a new one in it's place. */
    while (bcom_buffer_done(s->bcom_task)) {
    	bcom_retrieve_buffer(s->bcom_task, NULL, NULL);
    	s->period_current_pt += s->period_bytes;
    	if (s->period_current_pt >= s->period_end)
    		s->period_current_pt = s->period_start;
    	psc_dma_bcom_enqueue_next_buffer(s);
    	bcom_enable(s->bcom_task);
    }
/* If the stream is active, then also inform the PCM middle layer
     * of the period finished event. */
    if (s->active) {
    	s->jiffies = jiffies;
    	snd_pcm_period_elapsed(s->stream);
    }
return IRQ_HANDLED;
}
/**
 * psc_dma_startup: create a new substream
 *
 * This is the first function called when a stream is opened.
 *
 * If this is the first stream open, then grab the IRQ and program most of
 * the PSC registers.
 */
int mpc5200_dma_startup(struct snd_pcm_substream *substream,
    		   struct snd_soc_dai *dai)
{
    struct snd_soc_pcm_runtime *rtd = substream->private_data;
    struct psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
    int rc;
dev_dbg(psc_dma->dev, "psc_dma_startup(substream=%p)\n", substream);
if (!psc_dma->playback.active &&
        !psc_dma->capture.active) {
    	/* Setup the IRQs */
    	rc = request_irq(psc_dma->irq, &psc_dma_status_irq, IRQF_SHARED,
    			 "psc-dma-status", psc_dma);
    	rc |= request_irq(psc_dma->capture.irq,
    			  &psc_dma_bcom_irq, IRQF_SHARED,
    			  "psc-dma-capture", &psc_dma->capture);
    	rc |= request_irq(psc_dma->playback.irq,
    			  &psc_dma_bcom_irq, IRQF_SHARED,
    			  "psc-dma-playback", &psc_dma->playback);
    	if (rc) {
    		free_irq(psc_dma->irq, psc_dma);
    		free_irq(psc_dma->capture.irq,
    			 &psc_dma->capture);
    		free_irq(psc_dma->playback.irq,
    			 &psc_dma->playback);
    		return -ENODEV;
    	}
    }
return 0;
}
EXPORT_SYMBOL_GPL(mpc5200_dma_startup);
int mpc5200_dma_hw_free(struct snd_pcm_substream *substream,
    		   struct snd_soc_dai *dai)
{
    snd_pcm_set_runtime_buffer(substream, NULL);
    return 0;
}
EXPORT_SYMBOL_GPL(mpc5200_dma_hw_free);
/**
 * psc_dma_trigger: start and stop the DMA transfer.
 *
 * This function is called by ALSA to start, stop, pause, and resume the DMA
 * transfer of data.
 */
int mpc5200_dma_trigger(struct snd_pcm_substream *substream, int cmd,
    		   struct snd_soc_dai *dai)
{
    struct snd_soc_pcm_runtime *rtd = substream->private_data;
    struct psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
    struct snd_pcm_runtime *runtime = substream->runtime;
    struct psc_dma_stream *s;
    struct mpc52xx_psc __iomem *regs = psc_dma->psc_regs;
    u16 imr;
    u8 psc_cmd;
    unsigned long flags;
if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
    	s = &psc_dma->capture;
    else
    	s = &psc_dma->playback;
dev_dbg(psc_dma->dev, "psc_dma_trigger(substream=%p, cmd=%i)"
    	" stream_id=%i\n",
    	substream, cmd, substream->pstr->stream);
switch (cmd) {
    case SNDRV_PCM_TRIGGER_START:
    	s->period_bytes = frames_to_bytes(runtime,
    					  runtime->period_size);
    	s->period_start = virt_to_phys(runtime->dma_area);
    	s->period_end = s->period_start +
    			(s->period_bytes * runtime->periods);
    	s->period_next_pt = s->period_start;
    	s->period_current_pt = s->period_start;
    	s->active = 1;
/* First; reset everything */
    	if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE) {
    		out_8(&regs->command, MPC52xx_PSC_RST_RX);
    		out_8(&regs->command, MPC52xx_PSC_RST_ERR_STAT);
    	} else {
    		out_8(&regs->command, MPC52xx_PSC_RST_TX);
    		out_8(&regs->command, MPC52xx_PSC_RST_ERR_STAT);
    	}
/* Next, fill up the bestcomm bd queue and enable DMA.
    	 * This will begin filling the PSC's fifo. */
    	if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
    		bcom_gen_bd_rx_reset(s->bcom_task);
    	else
    		bcom_gen_bd_tx_reset(s->bcom_task);
    	while (!bcom_queue_full(s->bcom_task))
    		psc_dma_bcom_enqueue_next_buffer(s);
    	bcom_enable(s->bcom_task);
/* Due to errata in the dma mode; need to line up enabling
    	 * the transmitter with a transition on the frame sync
    	 * line */
spin_lock_irqsave(&psc_dma->lock, flags);
    	/* first make sure it is low */
    	while ((in_8(&regs->ipcr_acr.ipcr) & 0x80) != 0)
    		;
    	/* then wait for the transition to high */
    	while ((in_8(&regs->ipcr_acr.ipcr) & 0x80) == 0)
    		;
    	/* Finally, enable the PSC.
    	 * Receiver must always be enabled; even when we only want
    	 * transmit.  (see 15.3.2.3 of MPC5200B User's Guide) */
    	psc_cmd = MPC52xx_PSC_RX_ENABLE;
    	if (substream->pstr->stream == SNDRV_PCM_STREAM_PLAYBACK)
    		psc_cmd |= MPC52xx_PSC_TX_ENABLE;
    	out_8(&regs->command, psc_cmd);
    	spin_unlock_irqrestore(&psc_dma->lock, flags);
break;
case SNDRV_PCM_TRIGGER_STOP:
    	/* Turn off the PSC */
    	s->active = 0;
    	if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE) {
    		if (!psc_dma->playback.active) {
    			out_8(&regs->command, 2 << 4);	/* reset rx */
    			out_8(&regs->command, 3 << 4);	/* reset tx */
    			out_8(&regs->command, 4 << 4);	/* reset err */
    		}
    	} else {
    		out_8(&regs->command, 3 << 4);	/* reset tx */
    		out_8(&regs->command, 4 << 4);	/* reset err */
    		if (!psc_dma->capture.active)
    			out_8(&regs->command, 2 << 4);	/* reset rx */
    	}
bcom_disable(s->bcom_task);
    	while (!bcom_queue_empty(s->bcom_task))
    		bcom_retrieve_buffer(s->bcom_task, NULL, NULL);
break;
default:
    	dev_dbg(psc_dma->dev, "invalid command\n");
    	return -EINVAL;
    }
/* Update interrupt enable settings */
    imr = 0;
    if (psc_dma->playback.active)
    	imr |= MPC52xx_PSC_IMR_TXEMP;
    if (psc_dma->capture.active)
    	imr |= MPC52xx_PSC_IMR_ORERR;
    out_be16(&regs->isr_imr.imr, imr);
return 0;
}
EXPORT_SYMBOL_GPL(mpc5200_dma_trigger);
/**
 * psc_dma_shutdown: shutdown the data transfer on a stream
 *
 * Shutdown the PSC if there are no other substreams open.
 */
void mpc5200_dma_shutdown(struct snd_pcm_substream *substream,
    		     struct snd_soc_dai *dai)
{
    struct snd_soc_pcm_runtime *rtd = substream->private_data;
    struct psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
dev_dbg(psc_dma->dev, "psc_dma_shutdown(substream=%p)\n", substream);
/*
     * If this is the last active substream, disable the PSC and release
     * the IRQ.
     */
    if (!psc_dma->playback.active &&
        !psc_dma->capture.active) {
/* Disable all interrupts and reset the PSC */
    	out_be16(&psc_dma->psc_regs->isr_imr.imr, 0);
    	out_8(&psc_dma->psc_regs->command, 3 << 4); /* reset tx */
    	out_8(&psc_dma->psc_regs->command, 2 << 4); /* reset rx */
    	out_8(&psc_dma->psc_regs->command, 1 << 4); /* reset mode */
    	out_8(&psc_dma->psc_regs->command, 4 << 4); /* reset error */
/* Release irqs */
    	free_irq(psc_dma->irq, psc_dma);
    	free_irq(psc_dma->capture.irq, &psc_dma->capture);
    	free_irq(psc_dma->playback.irq, &psc_dma->playback);
    }
}
EXPORT_SYMBOL_GPL(mpc5200_dma_shutdown);
/* ---------------------------------------------------------------------
 * The PSC DMA 'ASoC platform' driver
 *
 * Can be referenced by an 'ASoC machine' driver
 * This driver only deals with the audio bus; it doesn't have any
 * interaction with the attached codec
 */
static const struct snd_pcm_hardware psc_dma_pcm_hardware = {
    .info = SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
    	SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER,
    .formats = SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_BE |
    	   SNDRV_PCM_FMTBIT_S24_BE | SNDRV_PCM_FMTBIT_S32_BE,
    .rate_min = 8000,
    .rate_max = 48000,
    .channels_min = 1,
    .channels_max = 2,
    .period_bytes_max	= 1024 * 1024,
    .period_bytes_min	= 32,
    .periods_min		= 2,
    .periods_max		= 256,
    .buffer_bytes_max	= 2 * 1024 * 1024,
    .fifo_size		= 0,
};
static int psc_dma_pcm_open(struct snd_pcm_substream *substream)
{
    struct snd_soc_pcm_runtime *rtd = substream->private_data;
    struct psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
    struct psc_dma_stream *s;
dev_dbg(psc_dma->dev, "psc_dma_pcm_open(substream=%p)\n", substream);
if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
    	s = &psc_dma->capture;
    else
    	s = &psc_dma->playback;
snd_soc_set_runtime_hwparams(substream, &psc_dma_pcm_hardware);
s->stream = substream;
    return 0;
}
static int psc_dma_pcm_close(struct snd_pcm_substream *substream)
{
    struct snd_soc_pcm_runtime *rtd = substream->private_data;
    struct psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
    struct psc_dma_stream *s;
dev_dbg(psc_dma->dev, "psc_dma_pcm_close(substream=%p)\n", substream);
if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
    	s = &psc_dma->capture;
    else
    	s = &psc_dma->playback;
s->stream = NULL;
    return 0;
}
static snd_pcm_uframes_t
psc_dma_pcm_pointer(struct snd_pcm_substream *substream)
{
    struct snd_pcm_runtime *runtime = substream->runtime;
    struct snd_soc_pcm_runtime *rtd = substream->private_data;
    struct psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
    struct psc_dma_stream *s;
    dma_addr_t count;
    snd_pcm_uframes_t frames;
    int delta;
if (substream->pstr->stream == SNDRV_PCM_STREAM_CAPTURE)
    	s = &psc_dma->capture;
    else
    	s = &psc_dma->playback;
count = s->period_current_pt - s->period_start;
delta = jiffies - s->jiffies;
    delta = delta * runtime->rate / HZ;
    frames = bytes_to_frames(substream->runtime, count);
return frames + delta;
}
static struct snd_pcm_ops psc_dma_pcm_ops = {
    .open		= psc_dma_pcm_open,
    .close		= psc_dma_pcm_close,
    .ioctl		= snd_pcm_lib_ioctl,
    .pointer	= psc_dma_pcm_pointer,
};
static u64 psc_dma_pcm_dmamask = 0xffffffff;
static int psc_dma_pcm_new(struct snd_card *card, struct snd_soc_dai *dai,
    		   struct snd_pcm *pcm)
{
    struct snd_soc_pcm_runtime *rtd = pcm->private_data;
    struct psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
    size_t size = psc_dma_pcm_hardware.buffer_bytes_max;
    int rc = 0;
dev_dbg(rtd->socdev->dev, "psc_dma_pcm_new(card=%p, dai=%p, pcm=%p)\n",
    	card, dai, pcm);
if (!card->dev->dma_mask)
    	card->dev->dma_mask = &psc_dma_pcm_dmamask;
    if (!card->dev->coherent_dma_mask)
    	card->dev->coherent_dma_mask = 0xffffffff;
if (pcm->streams[0].substream) {
    	rc = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, pcm->card->dev, size,
    				&pcm->streams[0].substream->dma_buffer);
    	if (rc)
    		goto playback_alloc_err;
    }
if (pcm->streams[1].substream) {
    	rc = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, pcm->card->dev, size,
    				&pcm->streams[1].substream->dma_buffer);
    	if (rc)
    		goto capture_alloc_err;
    }
if (rtd->socdev->card->codec->ac97)
    	rtd->socdev->card->codec->ac97->private_data = psc_dma;
return 0;
capture_alloc_err:
    if (pcm->streams[0].substream)
    	snd_dma_free_pages(&pcm->streams[0].substream->dma_buffer);
 playback_alloc_err:
    dev_err(card->dev, "Cannot allocate buffer(s)\n");
    return -ENOMEM;
}
static void psc_dma_pcm_free(struct snd_pcm *pcm)
{
    struct snd_soc_pcm_runtime *rtd = pcm->private_data;
    struct snd_pcm_substream *substream;
    int stream;
dev_dbg(rtd->socdev->dev, "psc_dma_pcm_free(pcm=%p)\n", pcm);
for (stream = 0; stream < 2; stream++) {
    	substream = pcm->streams[stream].substream;
    	if (substream) {
    		snd_dma_free_pages(&substream->dma_buffer);
    		substream->dma_buffer.area = NULL;
    		substream->dma_buffer.addr = 0;
    	}
    }
}
struct snd_soc_platform mpc5200_dma_platform = {
    .name		= "mpc5200-psc-audio",
    .pcm_ops	= &psc_dma_pcm_ops,
    .pcm_new	= &psc_dma_pcm_new,
    .pcm_free	= &psc_dma_pcm_free,
};
EXPORT_SYMBOL_GPL(mpc5200_dma_platform);
static int __init mpc5200_soc_platform_init(void)
{
    /* Tell the ASoC OF helpers about it */
    of_snd_soc_register_platform(&mpc5200_dma_platform);
    return snd_soc_register_platform(&mpc5200_dma_platform);
}
module_init(mpc5200_soc_platform_init);
static void __exit mpc5200_soc_platform_exit(void)
{
    snd_soc_unregister_platform(&mpc5200_dma_platform);
}
module_exit(mpc5200_soc_platform_exit);
-------------------------------------------------------------------------------
/*
 * linux/sound/mpc5200-ac97.c -- AC97 support for the Freescale MPC52xx chip.
 *
 * Copyright 2008 Jon Smirl, Digispeaker
 * Author: Jon Smirl jonsmirl@gmail.com
 *
 * 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.
 */
#define DEBUG
#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/dma-mapping.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/initval.h>
#include <sound/soc.h>
#include <sound/soc-of-simple.h>
#include <sysdev/bestcomm/bestcomm.h>
#include <sysdev/bestcomm/gen_bd.h>
#include <asm/time.h>
#include <asm/mpc52xx.h>
#include <asm/mpc52xx_psc.h>
#include "mpc5200_dma.h"
#include "mpc5200_psc_ac97.h"
MODULE_AUTHOR("Jon Smirl jonsmirl@gmail.com");
MODULE_DESCRIPTION("mpc5200 AC97 module");
MODULE_LICENSE("GPL");
#define DRV_NAME "mpc5200-psc-ac97"
static unsigned short psc_ac97_read(struct snd_ac97 *ac97, unsigned short reg)
{
    struct psc_dma *psc_dma = ac97->private_data;
    int timeout;
    unsigned int val;
spin_lock(&psc_dma->lock);
    //printk("ac97 read: reg %04x\n", reg);
/* Wait for it to be ready */
    timeout = 1000;
    while ((--timeout) && (in_be16(&psc_dma->psc_regs->sr_csr.status) &
    					MPC52xx_PSC_SR_CMDSEND) )
    	udelay(10);
if (!timeout) {
    	printk(KERN_ERR DRV_NAME ": timeout on ac97 bus (rdy)\n");
    	return 0xffff;
    }
/* Do the read */
    out_be32(&psc_dma->psc_regs->ac97_cmd, (1<<31) | ((reg & 0x7f) << 24));
/* Wait for the answer */
    timeout = 1000;
    while ((--timeout) && !(in_be16(&psc_dma->psc_regs->sr_csr.status) &
    					MPC52xx_PSC_SR_DATA_VAL) )
    	udelay(10);
if (!timeout) {
    	printk(KERN_ERR DRV_NAME ": timeout on ac97 read (val) %x\n",
in_be16(&psc_dma->psc_regs->sr_csr.status));
    	return 0xffff;
    }
/* Get the data */
    val = in_be32(&psc_dma->psc_regs->ac97_data);
    if ( ((val>>24) & 0x7f) != reg ) {
    	printk(KERN_ERR DRV_NAME ": reg echo error on ac97 read\n");
    	return 0xffff;
    }
    val = (val >> 8) & 0xffff;
//printk("ac97 read ok: reg %04x  val %04x\n", reg, val);
spin_unlock(&psc_dma->lock);
    return (unsigned short) val;
}
static void psc_ac97_write(struct snd_ac97 *ac97, unsigned short reg,
unsigned short val)
{
    struct psc_dma *psc_dma = ac97->private_data;
    int timeout;
//printk("ac97 write: reg %04x  val %04x\n", reg, val);
    spin_lock(&psc_dma->lock);
/* Wait for it to be ready */
    timeout = 1000;
    while ((--timeout) && (in_be16(&psc_dma->psc_regs->sr_csr.status) &
    					MPC52xx_PSC_SR_CMDSEND) )
    	udelay(10);
if (!timeout) {
    	printk(KERN_ERR DRV_NAME ": timeout on ac97 write\n");
    	return;
    }
/* Write data */
    out_be32(&psc_dma->psc_regs->ac97_cmd, ((reg & 0x7f) << 24) | (val << 8));
spin_unlock(&psc_dma->lock);
}
static void psc_ac97_cold_reset(struct snd_ac97 *ac97)
{
    struct psc_dma *psc_dma = ac97->private_data;
printk("psc_ac97_cold_reset %p\n", ac97);
/* Do a cold reset */
    out_8(&psc_dma->psc_regs->op1, MPC52xx_PSC_OP_RES);
    udelay(10);
    out_8(&psc_dma->psc_regs->op0, MPC52xx_PSC_OP_RES);
    udelay(50);
/* PSC recover from cold reset (cfr user manual, not sure if useful) */
    out_be32(&psc_dma->psc_regs->sicr, in_be32(&psc_dma->psc_regs->sicr));
}
static void psc_ac97_warm_reset(struct snd_ac97 *ac97)
{
    printk("psc_ac97_warm_reset\n");
}
struct snd_ac97_bus_ops soc_ac97_ops = {
    .read		= psc_ac97_read,
    .write		= psc_ac97_write,
    .reset		= psc_ac97_cold_reset,
    .warm_reset	= psc_ac97_warm_reset,
};
EXPORT_SYMBOL_GPL(soc_ac97_ops);
#ifdef CONFIG_PM
static int psc_ac97_suspend(struct snd_soc_dai *dai)
{
    return 0;
}
static int psc_ac97_resume(struct snd_soc_dai *dai)
{
    return 0;
}
#else
#define psc_ac97_suspend	NULL
#define psc_ac97_resume	NULL
#endif
static int psc_ac97_hw_analog_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 psc_dma *psc_dma = rtd->dai->cpu_dai->private_data;
dev_dbg(psc_dma->dev, "%s(substream=%p) p_size=%i p_bytes=%i"
    	" periods=%i buffer_size=%i  buffer_bytes=%i channels=%i"
    	" rate=%i format=%i\n",
    	__func__, substream, params_period_size(params),
    	params_period_bytes(params), params_periods(params),
    	params_buffer_size(params), params_buffer_bytes(params),
    	params_channels(params), params_rate(params), params_format(params));
// FIXME, need a spinlock to protect access
    if (params_channels(params) == 1)
    	out_be32(&psc_dma->psc_regs->ac97_slots, 0x01000000);
    else
    	out_be32(&psc_dma->psc_regs->ac97_slots, 0x03000000);
snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
return 0;
}
static int psc_ac97_hw_digital_params(struct snd_pcm_substream *substream,
    			 struct snd_pcm_hw_params *params,
    			 struct snd_soc_dai *dai)
{
    return 0;
}
/**
 * psc_ac97_set_fmt: set the serial format.
 *
 * This function is called by the machine driver to tell us what serial
 * format to use.
 *
 * This driver only supports AC97 mode.  Return an error if the format is
 * not SND_SOC_DAIFMT_AC97.
 *
 * @format: one of SND_SOC_DAIFMT_xxx
 */
static int psc_ac97_set_fmt(struct snd_soc_dai *cpu_dai, unsigned int format)
{
    struct psc_dma *psc_dma = cpu_dai->private_data;
    dev_dbg(psc_dma->dev, "psc_ac97_set_fmt(cpu_dai=%p, format=%i)\n",
    			cpu_dai, format);
    return (format == SND_SOC_DAIFMT_AC97) ? 0 : -EINVAL;
}
/* ---------------------------------------------------------------------
 * ALSA SoC Bindings
 *
 * - Digital Audio Interface (DAI) template
 * - create/destroy dai hooks
 */
/**
 * psc_ac97_dai_template: template CPU Digital Audio Interface
 */
static struct snd_soc_dai_ops psc_ac97_analog_ops = {
    .startup	= mpc5200_dma_startup,
    .hw_params	= psc_ac97_hw_analog_params,
    .hw_free	= mpc5200_dma_hw_free,
    .shutdown	= mpc5200_dma_shutdown,
    .trigger	= mpc5200_dma_trigger,
    .set_fmt	= psc_ac97_set_fmt,
};
static struct snd_soc_dai_ops psc_ac97_digital_ops = {
    .startup	= mpc5200_dma_startup,
    .hw_params	= psc_ac97_hw_digital_params,
    .hw_free	= mpc5200_dma_hw_free,
    .shutdown	= mpc5200_dma_shutdown,
    .trigger	= mpc5200_dma_trigger,
    .set_fmt	= psc_ac97_set_fmt,
};
static struct snd_soc_dai psc_ac97_dai_template[] = {
{
    .name	= "%s analog",
    .suspend = psc_ac97_suspend,
    .resume = psc_ac97_resume,
    .playback = {
    	.channels_min	= 1,
    	.channels_max	= 6,
    	.rates		= SNDRV_PCM_RATE_8000_48000,
    	.formats	= SNDRV_PCM_FMTBIT_S32_BE,
    },
    .capture = {
    	.channels_min	= 1,
    	.channels_max	= 2,
    	.rates		= SNDRV_PCM_RATE_8000_48000,
    	.formats	= SNDRV_PCM_FMTBIT_S32_BE,
    },
    .ops = &psc_ac97_analog_ops,
},
{
    .name	= "%s digital",
    .playback = {
    	.channels_min	= 1,
    	.channels_max	= 2,
    	.rates		= SNDRV_PCM_RATE_32000 | \
    		SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000,
    	.formats	= SNDRV_PCM_FORMAT_IEC958_SUBFRAME_BE,
    },
    .ops = &psc_ac97_digital_ops,
}};
/* ---------------------------------------------------------------------
 * Sysfs attributes for debugging
 */
static ssize_t psc_ac97_status_show(struct device *dev,
    		   struct device_attribute *attr, char *buf)
{
    struct psc_dma *psc_dma = dev_get_drvdata(dev);
return sprintf(buf, "status=%.4x sicr=%.8x rfnum=%i rfstat=0x%.4x "
    		"tfnum=%i tfstat=0x%.4x\n",
    		in_be16(&psc_dma->psc_regs->sr_csr.status),
    		in_be32(&psc_dma->psc_regs->sicr),
    		in_be16(&psc_dma->fifo_regs->rfnum) & 0x1ff,
    		in_be16(&psc_dma->fifo_regs->rfstat),
    		in_be16(&psc_dma->fifo_regs->tfnum) & 0x1ff,
    		in_be16(&psc_dma->fifo_regs->tfstat));
}
static int *psc_ac97_get_stat_attr(struct psc_dma *psc_dma, const char *name)
{
    if (strcmp(name, "playback_underrun") == 0)
    	return &psc_dma->stats.underrun_count;
    if (strcmp(name, "capture_overrun") == 0)
    	return &psc_dma->stats.overrun_count;
return NULL;
}
static ssize_t psc_ac97_stat_show(struct device *dev,
    			 struct device_attribute *attr, char *buf)
{
    struct psc_dma *psc_dma = dev_get_drvdata(dev);
    int *attrib;
attrib = psc_ac97_get_stat_attr(psc_dma, attr->attr.name);
    if (!attrib)
    	return 0;
return sprintf(buf, "%i\n", *attrib);
}
static ssize_t psc_ac97_stat_store(struct device *dev,
    			  struct device_attribute *attr,
    			  const char *buf,
    			  size_t count)
{
    struct psc_dma *psc_dma = dev_get_drvdata(dev);
    int *attrib;
attrib = psc_ac97_get_stat_attr(psc_dma, attr->attr.name);
    if (!attrib)
    	return 0;
*attrib = simple_strtoul(buf, NULL, 0);
    return count;
}
static DEVICE_ATTR(status, 0644, psc_ac97_status_show, NULL);
static DEVICE_ATTR(playback_underrun, 0644, psc_ac97_stat_show,
    		psc_ac97_stat_store);
static DEVICE_ATTR(capture_overrun, 0644, psc_ac97_stat_show,
    		psc_ac97_stat_store);
/* ---------------------------------------------------------------------
 * OF platform bus binding code:
 * - Probe/remove operations
 * - OF device match table
 */
static int __devinit psc_ac97_of_probe(struct of_device *op,
    			      const struct of_device_id *match)
{
    phys_addr_t fifo;
    struct psc_dma *psc_dma;
    struct resource res;
    int i, nDAI, size, psc_id, irq, rc;
    const __be32 *prop;
    void __iomem *regs;
/* Get the PSC ID */
    prop = of_get_property(op->node, "cell-index", &size);
    if (!prop || size < sizeof *prop)
    	return -ENODEV;
    psc_id = be32_to_cpu(*prop);
/* Fetch the registers and IRQ of the PSC */
    irq = irq_of_parse_and_map(op->node, 0);
    if (of_address_to_resource(op->node, 0, &res)) {
    	dev_err(&op->dev, "Missing reg property\n");
    	return -ENODEV;
    }
    regs = ioremap(res.start, 1 + res.end - res.start);
    if (!regs) {
    	dev_err(&op->dev, "Could not map registers\n");
    	return -ENODEV;
    }
/* Allocate and initialize the driver private data */
    psc_dma = kzalloc(sizeof *psc_dma, GFP_KERNEL);
    if (!psc_dma) {
    	iounmap(regs);
    	return -ENOMEM;
    }
    printk("psc_dma %p\n", psc_dma);
spin_lock_init(&psc_dma->lock);
    psc_dma->irq = irq;
    psc_dma->psc_regs = regs;
    psc_dma->fifo_regs = regs + sizeof *psc_dma->psc_regs;
    psc_dma->dev = &op->dev;
    psc_dma->playback.psc_dma = psc_dma;
    psc_dma->capture.psc_dma = psc_dma;
    snprintf(psc_dma->name, sizeof psc_dma->name, "PSC%u AC97", psc_id+1);
/* Fill out the CPU DAI structure */
    nDAI = ARRAY_SIZE(psc_ac97_dai_template);
    nDAI = min(nDAI, SOC_OF_SIMPLE_MAX_DAI);
    for (i = 0; i < nDAI; i++) {
    	memcpy(&psc_dma->dai[i], &psc_ac97_dai_template[i], sizeof(struct
snd_soc_dai));
    	psc_dma->dai[i].private_data = psc_dma;
    	snprintf(psc_dma->stream_name[i], PSC_STREAM_NAME_LEN,
psc_ac97_dai_template[i].name, psc_dma->name);
    	psc_dma->dai[i].name = psc_dma->stream_name[i];
    	psc_dma->dai[i].id = psc_id;
    }
/* Find the address of the fifo data registers and setup the
     * DMA tasks */
    fifo = res.start + offsetof(struct mpc52xx_psc, buffer.buffer_32);
    psc_dma->capture.bcom_task =
    	bcom_psc_gen_bd_rx_init(psc_id, 10, fifo, 512);
    psc_dma->playback.bcom_task =
    	bcom_psc_gen_bd_tx_init(psc_id, 10, fifo);
    if (!psc_dma->capture.bcom_task ||
        !psc_dma->playback.bcom_task) {
    	dev_err(&op->dev, "Could not allocate bestcomm tasks\n");
    	iounmap(regs);
    	kfree(psc_dma);
    	return -ENODEV;
    }
/* Disable all interrupts and reset the PSC */
    out_be16(&psc_dma->psc_regs->isr_imr.imr, 0);
    out_8(&psc_dma->psc_regs->command, MPC52xx_PSC_RST_RX); /* reset receiver */
    out_8(&psc_dma->psc_regs->command, MPC52xx_PSC_RST_TX); /* reset transmitter */
    out_8(&psc_dma->psc_regs->command, MPC52xx_PSC_RST_ERR_STAT); /* reset error */
    out_8(&psc_dma->psc_regs->command, MPC52xx_PSC_SEL_MODE_REG_1); /*
reset mode */
/* Do a cold reset of codec */
    out_8(&psc_dma->psc_regs->op1, MPC52xx_PSC_OP_RES);
    udelay(10);
    out_8(&psc_dma->psc_regs->op0, MPC52xx_PSC_OP_RES);
    udelay(50);
/* Configure the serial interface mode to AC97 */
    psc_dma->sicr = MPC52xx_PSC_SICR_SIM_AC97 | MPC52xx_PSC_SICR_ENAC97;
    out_be32(&psc_dma->psc_regs->sicr, psc_dma->sicr);
/* No slots active */
    out_be32(&psc_dma->psc_regs->ac97_slots, 0x00000000);
/* Set up mode register;
     * First write: RxRdy (FIFO Alarm) generates rx FIFO irq
     * Second write: register Normal mode for non loopback
     */
    out_8(&psc_dma->psc_regs->mode, 0);
    out_8(&psc_dma->psc_regs->mode, 0);
/* Set the TX and RX fifo alarm thresholds */
    out_be16(&psc_dma->fifo_regs->rfalarm, 0x100);
    out_8(&psc_dma->fifo_regs->rfcntl, 0x4);
    out_be16(&psc_dma->fifo_regs->tfalarm, 0x100);
    out_8(&psc_dma->fifo_regs->tfcntl, 0x7);
/* Go */
    out_8(&psc_dma->psc_regs->command, MPC52xx_PSC_TX_ENABLE);
    out_8(&psc_dma->psc_regs->command, MPC52xx_PSC_RX_ENABLE);
/* Lookup the IRQ numbers */
    psc_dma->playback.irq =
    	bcom_get_task_irq(psc_dma->playback.bcom_task);
    psc_dma->capture.irq =
    	bcom_get_task_irq(psc_dma->capture.bcom_task);
/* Save what we've done so it can be found again later */
    dev_set_drvdata(&op->dev, psc_dma);
/* Register the SYSFS files */
    rc = device_create_file(psc_dma->dev, &dev_attr_status);
    rc |= device_create_file(psc_dma->dev, &dev_attr_capture_overrun);
    rc |= device_create_file(psc_dma->dev, &dev_attr_playback_underrun);
    if (rc)
    	dev_info(psc_dma->dev, "error creating sysfs files\n");
rc = snd_soc_register_dais(psc_dma->dai, nDAI);
    if (rc != 0) {
    	printk("Failed to register DAI\n");
    	return 0;
    }
/* Tell the ASoC OF helpers about it */
    of_snd_soc_register_cpu_dai(op->node, psc_dma->dai, nDAI);
return 0;
}
static int __devexit psc_ac97_of_remove(struct of_device *op)
{
    struct psc_dma *psc_dma = dev_get_drvdata(&op->dev);
dev_dbg(&op->dev, "psc_ac97_remove()\n");
bcom_gen_bd_rx_release(psc_dma->capture.bcom_task);
    bcom_gen_bd_tx_release(psc_dma->playback.bcom_task);
iounmap(psc_dma->psc_regs);
    iounmap(psc_dma->fifo_regs);
    kfree(psc_dma);
    dev_set_drvdata(&op->dev, NULL);
return 0;
}
/* Match table for of_platform binding */
static struct of_device_id psc_ac97_match[] __devinitdata = {
    { .compatible = "fsl,mpc5200-psc-ac97", },
    {}
};
MODULE_DEVICE_TABLE(of, psc_ac97_match);
static struct of_platform_driver psc_ac97_driver = {
    .match_table = psc_ac97_match,
    .probe = psc_ac97_of_probe,
    .remove = __devexit_p(psc_ac97_of_remove),
    .driver = {
    	.name = "mpc5200-psc-ac97",
    	.owner = THIS_MODULE,
    },
};
/* ---------------------------------------------------------------------
 * Module setup and teardown; simply register the of_platform driver
 * for the PSC in AC97 mode.
 */
static int __init psc_ac97_init(void)
{
    return of_register_platform_driver(&psc_ac97_driver);
}
module_init(psc_ac97_init);
static void __exit psc_ac97_exit(void)
{
    of_unregister_platform_driver(&psc_ac97_driver);
}
module_exit(psc_ac97_exit);
-- 
Jon Smirl
jonsmirl@gmail.com