/*
* Driver for WM8725 16-bit stereo DAC connected to Atmel SSC
*
* Copyright (C) 2006-2007 Atmel Norway
*
* 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/err.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/io.h>

#include <sound/initval.h>
#include <sound/control.h>
#include <sound/core.h>
#include <sound/pcm.h>

#include <linux/atmel-ssc.h>
#include <mach/at91_tc.h>
#include <mach/gpio.h>

#define BITRATE_TARGET 48000

struct snd_wm8725 {
struct snd_card *card;
struct snd_pcm *pcm;
struct snd_pcm_substream *substream;
int irq;
int period;
unsigned long bitrate;
struct clk *bitclk;
struct ssc_device *ssc;
struct platform_device *pdev;
/* Protect SSC registers against concurrent access. */
spinlock_t lock;
};

#define get_chip(card) ((struct snd_wm8725 *)card->private_data)

static struct snd_pcm_hardware snd_wm8725_playback_hw = {
.info = SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_BLOCK_TRANSFER,
.formats = SNDRV_PCM_FMTBIT_S16_BE,
.rates = SNDRV_PCM_RATE_CONTINUOUS,
.rate_min = 8000, /* Replaced by chip->bitrate later. */
.rate_max = 50000, /* Replaced by chip->bitrate later. */
.channels_min = 1,
.channels_max = 2,
.buffer_bytes_max = 64 * 1024 - 1,
.period_bytes_min = 512,
.period_bytes_max = 64 * 1024 - 1,
.periods_min = 4,
.periods_max = 1024,
};

/*
* Calculate and set bitrate and divisions.
*/
static int snd_wm8725_set_bitrate(struct snd_wm8725 *chip)
{
unsigned long ssc_rate = clk_get_rate(chip->ssc->clk);
unsigned long ssc_div;

/*
* The DAC master clock (MCLK) is programmable, and is either 256
* or (not here) 384 times the I2S output clock (BCLK).
*/

/* SSC clock / (bitrate * stereo * 16-bit). */
ssc_div = ssc_rate / (BITRATE_TARGET * 2 * 16);

/* Set divider in SSC device. */
ssc_writel(chip->ssc->regs, CMR, ssc_div/2);

/* SSC clock / (ssc divider * 16-bit * stereo). */
chip->bitrate = ssc_rate / (ssc_div * 16 * 2);

printk(KERN_INFO "wm8725: supported bitrate is %lu (%lu divider)\n",
chip->bitrate, ssc_div);

return 0;
}

static int snd_wm8725_pcm_open(struct snd_pcm_substream *substream)
{
struct snd_wm8725 *chip = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
int err;

/* ensure buffer_size is a multiple of period_size */
err = snd_pcm_hw_constraint_integer(runtime,
SNDRV_PCM_HW_PARAM_PERIODS);
if (err < 0)
return err;
snd_wm8725_playback_hw.rate_min = chip->bitrate;
snd_wm8725_playback_hw.rate_max = chip->bitrate;
runtime->hw = snd_wm8725_playback_hw;
chip->substream = substream;

return 0;
}

static int snd_wm8725_pcm_close(struct snd_pcm_substream *substream)
{
struct snd_wm8725 *chip = snd_pcm_substream_chip(substream);
chip->substream = NULL;
return 0;
}

static int snd_wm8725_pcm_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *hw_params)
{
struct snd_wm8725 *chip = snd_pcm_substream_chip(substream);
int channels = params_channels(hw_params);
int val;

val = ssc_readl(chip->ssc->regs, TFMR);
val = SSC_BFINS(TFMR_DATNB, channels - 1, val);
ssc_writel(chip->ssc->regs, TFMR, val);

return snd_pcm_lib_malloc_pages(substream,
params_buffer_bytes(hw_params));
}

static int snd_wm8725_pcm_hw_free(struct snd_pcm_substream *substream)
{
return snd_pcm_lib_free_pages(substream);
}

static int snd_wm8725_pcm_prepare(struct snd_pcm_substream *substream)
{
struct snd_wm8725 *chip = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
int block_size;

block_size = frames_to_bytes(runtime, runtime->period_size);

chip->period = 0;

ssc_writel(chip->ssc->regs, PDC_TPR,
(long)runtime->dma_addr);
ssc_writel(chip->ssc->regs, PDC_TCR,
runtime->period_size * runtime->channels);
ssc_writel(chip->ssc->regs, PDC_TNPR,
(long)runtime->dma_addr + block_size);
ssc_writel(chip->ssc->regs, PDC_TNCR,
runtime->period_size * runtime->channels);

return 0;
}

static int snd_wm8725_pcm_trigger(struct snd_pcm_substream *substream,
int cmd)
{
struct snd_wm8725 *chip = snd_pcm_substream_chip(substream);
int retval = 0;

spin_lock(&chip->lock);

switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
ssc_writel(chip->ssc->regs, IER, SSC_BIT(IER_ENDTX));
ssc_writel(chip->ssc->regs, PDC_PTCR, SSC_BIT(PDC_PTCR_TXTEN));
break;
case SNDRV_PCM_TRIGGER_STOP:
ssc_writel(chip->ssc->regs, PDC_PTCR, SSC_BIT(PDC_PTCR_TXTDIS));
ssc_writel(chip->ssc->regs, IDR, SSC_BIT(IDR_ENDTX));
break;
default:
dev_dbg(&chip->pdev->dev, "spurious command %x\n", cmd);
retval = -EINVAL;
break;
}

spin_unlock(&chip->lock);

return retval;
}

static snd_pcm_uframes_t
snd_wm8725_pcm_pointer(struct snd_pcm_substream *substream)
{
struct snd_wm8725 *chip = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_uframes_t pos;
unsigned long bytes;

bytes = ssc_readl(chip->ssc->regs, PDC_TPR)
- (unsigned long)runtime->dma_addr;

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

return pos;
}

static struct snd_pcm_ops wm8725_playback_ops = {
.open = snd_wm8725_pcm_open,
.close = snd_wm8725_pcm_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = snd_wm8725_pcm_hw_params,
.hw_free = snd_wm8725_pcm_hw_free,
.prepare = snd_wm8725_pcm_prepare,
.trigger = snd_wm8725_pcm_trigger,
.pointer = snd_wm8725_pcm_pointer,
};

static int __init snd_wm8725_pcm_new(struct snd_wm8725 *chip, int device)
{
struct snd_pcm *pcm;
int retval;

retval = snd_pcm_new(chip->card, chip->card->shortname,
device, 1, 0, &pcm);
if (retval < 0)
goto out;

pcm->private_data = chip;
pcm->info_flags = SNDRV_PCM_INFO_BLOCK_TRANSFER;
strcpy(pcm->name, "wm8725");
chip->pcm = pcm;

snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &wm8725_playback_ops);

retval = snd_pcm_lib_preallocate_pages_for_all(chip->pcm,
SNDRV_DMA_TYPE_DEV, &chip->ssc->pdev->dev,
64 * 1024, 64 * 1024);
out:
return retval;
}

static irqreturn_t snd_wm8725_interrupt(int irq, void *dev_id)
{
struct snd_wm8725 *chip = dev_id;
struct snd_pcm_runtime *runtime = chip->substream->runtime;
u32 status;
int offset;
int block_size;
int next_period;
int retval = IRQ_NONE;

spin_lock(&chip->lock);

block_size = frames_to_bytes(runtime, runtime->period_size);
status = ssc_readl(chip->ssc->regs, IMR);

if (status & SSC_BIT(IMR_ENDTX)) {
chip->period++;
if (chip->period == runtime->periods)
chip->period = 0;
next_period = chip->period + 1;
if (next_period == runtime->periods)
next_period = 0;

offset = block_size * next_period;

ssc_writel(chip->ssc->regs, PDC_TNPR,
(long)runtime->dma_addr + offset);
ssc_writel(chip->ssc->regs, PDC_TNCR,
runtime->period_size * runtime->channels);
retval = IRQ_HANDLED;
}

ssc_readl(chip->ssc->regs, IMR);
spin_unlock(&chip->lock);

if (status & SSC_BIT(IMR_ENDTX))
snd_pcm_period_elapsed(chip->substream);

return retval;
}

/*
* Device functions
*/
static int __init snd_wm8725_ssc_init(struct snd_wm8725 *chip)
{
/*
* Continuous clock output.
* Starts on falling TF.
* Delay 1 cycle (1 bit).
* Periode is 16 bit (16 - 1).
*/
ssc_writel(chip->ssc->regs, TCMR,
SSC_BF(TCMR_CKO, 1)
| SSC_BF(TCMR_START, 4)
// | SSC_BF(TCMR_STTDLY, 1)
| SSC_BF(TCMR_PERIOD, 16 - 1));
/*
* Data length is 16 bit (16 - 1).
* Transmit MSB first.
* Transmit 2 words each transfer.
* Frame sync length is 16 bit (16 - 1).
* Frame starts on negative pulse.
*/
ssc_writel(chip->ssc->regs, TFMR,
SSC_BF(TFMR_DATLEN, 16 - 1)
| SSC_BIT(TFMR_MSBF)
| SSC_BF(TFMR_DATNB, 1)
| SSC_BF(TFMR_FSLEN, 16 - 1)
| SSC_BF(TFMR_FSOS, 1));

return 0;
}

#define at91_tc_read(reg) __raw_readl(tc0_base + (reg))
#define at91_tc_write(reg, val) __raw_writel((val), tc0_base + (reg))

static int __init snd_wm8725_chip_init(struct snd_wm8725 *chip)
{
int retval;
void __iomem *tc0_base;
struct clk *tc0_clk;

retval = snd_wm8725_set_bitrate(chip);

/* Enable DAC master clock. */
tc0_clk = clk_get(NULL, "tc0_clk");
clk_enable(tc0_clk);

tc0_base = ioremap_nocache(AT91SAM9260_BASE_TC0, 256);
if (!tc0_base) {
clk_disable(tc0_clk);
printk(KERN_ERR "at91adc: Can't remap TC0 register area\n");
return -EACCES;
}

at91_set_A_periph(AT91_PIN_PA26, 0);

at91_tc_write(AT91_TC_CMR, AT91_TC_WAVE | AT91_TC_WAVESEL_UP_AUTO
| AT91_TC_TIMER_CLOCK1 | AT91_TC_ACPA_SET | AT91_TC_ACPC_CLEAR);

/* set rate */
at91_tc_write(AT91_TC_RC, 4);
/* duty 50 % */
at91_tc_write(AT91_TC_RA, 2);

at91_tc_write(AT91_TC_IDR, -1);

at91_tc_write(AT91_TC_CCR, AT91_TC_SWTRG | AT91_TC_CLKEN);

/* Enable I2S device, i.e. clock output. */
ssc_writel(chip->ssc->regs, CR, SSC_BIT(CR_TXEN));

return retval;
}

static int snd_wm8725_dev_free(struct snd_device *device)
{
struct snd_wm8725 *chip = device->device_data;

ssc_writel(chip->ssc->regs, CR, SSC_BIT(CR_TXDIS));
if (chip->irq >= 0) {
free_irq(chip->irq, chip);
chip->irq = -1;
}

return 0;
}

static int __init snd_wm8725_dev_init(struct snd_card *card,
struct platform_device *pdev)
{
static struct snd_device_ops ops = {
.dev_free = snd_wm8725_dev_free,
};
struct snd_wm8725 *chip = get_chip(card);
int irq, retval;

irq = chip->ssc->irq;
if (irq < 0)
return irq;

spin_lock_init(&chip->lock);
chip->card = card;
chip->irq = -1;

retval = request_irq(irq, snd_wm8725_interrupt, 0, "wm8725", chip);
if (retval) {
dev_dbg(&pdev->dev, "unable to request irq %d\n", irq);
goto out;
}
chip->irq = irq;

retval = snd_wm8725_ssc_init(chip);
if (retval)
goto out_irq;

retval = snd_wm8725_chip_init(chip);
if (retval)
goto out_irq;

retval = snd_wm8725_pcm_new(chip, 0);
if (retval)
goto out_irq;

retval = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
if (retval)
goto out_irq;

snd_card_set_dev(card, &pdev->dev);

goto out;

out_irq:
free_irq(chip->irq, chip);
chip->irq = -1;
out:
return retval;
}

static int __init snd_wm8725_probe(struct platform_device *pdev)
{
struct snd_card *card;
struct snd_wm8725 *chip;
int retval;
char id[16];

retval = -ENOMEM;

/* Allocate "card" using some unused identifiers. */
snprintf(id, sizeof id, "wm8725_%d", 0);
card = snd_card_new(-1, id, THIS_MODULE, sizeof(struct snd_wm8725));
if (!card)
goto out;

chip = card->private_data;
chip->pdev = pdev;

chip->ssc = ssc_request(0);
if (IS_ERR(chip->ssc)) {
dev_dbg(&pdev->dev, "could not get ssc%d device\n", 0);
retval = PTR_ERR(chip->ssc);
goto out_card;
}

retval = snd_wm8725_dev_init(card, pdev);
if (retval)
goto out_ssc;

strcpy(card->driver, "wm8725");
strcpy(card->shortname, "AT91SAM9260-EK external DAC");
sprintf(card->longname, "%s on irq %d", card->shortname, chip->irq);

retval = snd_card_register(card);
if (retval)
goto out_ssc;

platform_set_drvdata(pdev, card);

goto out;

out_ssc:
ssc_free(chip->ssc);
out_card:
snd_card_free(card);
out:
return retval;
}

static int snd_wm8725_remove(struct platform_device *pdev)
{
struct snd_card *card = platform_get_drvdata(pdev);
struct snd_wm8725 *chip = card->private_data;

/* Stop playback. */
ssc_writel(chip->ssc->regs, CR, SSC_BIT(CR_TXDIS));

ssc_free(chip->ssc);
snd_card_free(card);

return 0;
}

static struct platform_driver wm8725_driver = {
.driver = {
.name = "wm8725",
},
.probe = snd_wm8725_probe,
.remove = snd_wm8725_remove,
};

static struct platform_device *wm8725_device;

static int __init wm8725_init(void)
{
int ret = 0;

ret = platform_driver_register(&wm8725_driver);

if (!ret) {
wm8725_device = platform_device_alloc("wm8725", 0);

if (wm8725_device)
ret = platform_device_add(wm8725_device);
else
ret = -ENOMEM;

if (ret) {
platform_device_put(wm8725_device);
platform_driver_unregister(&wm8725_driver);
}
}

return ret;
}

static void __exit wm8725_exit(void)
{
platform_device_unregister(wm8725_device);
platform_driver_unregister(&wm8725_driver);
}

module_init(wm8725_init);
module_exit(wm8725_exit);


MODULE_AUTHOR("Alexander Kudjashev");
MODULE_DESCRIPTION("Sound driver for WM8725 with Atmel SSC");
MODULE_LICENSE("GPL");

код кусь-кусь