Driving an ads1278 as an audio device using modified ads117x.c codec source (ALSA)

...here's the source:

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/initval.h>
#include <sound/soc.h>

#define ADS127X_RATES (SNDRV_PCM_RATE_8000_48000)
#define ADS127X_FORMATS (SNDRV_PCM_FMTBIT_S24_LE)

static struct snd_soc_dai_driver ads127x_dai = {
/* ADC */
.name = "ads127x-hifi",
.capture = {
.stream_name = "Capture",
.channels_min = 1,
.channels_max = 16,
.rates = ADS127X_RATES,
.formats = ADS127X_FORMATS,},
};

static struct snd_soc_codec_driver soc_codec_dev_ads127x;

static __devinit int ads127x_probe(struct platform_device *pdev)
{
return snd_soc_register_codec(&pdev->dev,
&soc_codec_dev_ads127x, &ads127x_dai, 1);
}

static int __devexit ads127x_remove(struct platform_device *pdev)
{
printk("ADS127, remove audio driver\n");
snd_soc_unregister_codec(&pdev->dev);
return 0;
}

static struct platform_driver ads127x_codec_driver = {
.driver = {
.name = "ads127x-codec",
.owner = THIS_MODULE,
},

.probe = ads127x_probe,
.remove = __devexit_p(ads127x_remove),
};

static int __init ads127x_init(void)
{
printk("ADS127x, load audio driver\n");
return platform_driver_register(&ads127x_codec_driver);
}
module_init(ads127x_init);

static void __exit ads127x_exit(void)
{
platform_driver_unregister(&ads127x_codec_driver);
}
module_exit(ads127x_exit);

I assume that it is probably the best to use the davinci-pcm-audio platform driver. Is that right?
I modified following:

Index: git/arch/arm/mach-omap2/devices.c
===================================================================
--- git.orig/arch/arm/mach-omap2/devices.c    2012-07-20 16:22:26.324602816 +0200
+++ git/arch/arm/mach-omap2/devices.c          2012-07-26 13:20:17.124821103 +0200
@@ -231,10 +231,16 @@
               .id                          = -1,
};
 
+struct platform_device ads117x_codec= {
+             .name                  = "ads117x-codec",
+             .id                          = -1,
+};
+
static void am33xx_init_pcm(void)
{
-              printk("cape: pcm register");
+             printk("Multisensor cape: pcm register");
               platform_device_register(&am33xx_pcm_device);
+             platform_device_register(&ads117x_codec);
}
 
 #else
 
After this changes, I can find codec and dai in /sys/kernel/debug/asoc:
root@beaglebone:/sys/kernel/debug/asoc# cat codecs
tlv320aic3x-codec.3-001b
ads117x-codec
root@beaglebone:/sys/kernel/debug/asoc# cat dais
davinci-mcasp.1
davinci-mcasp.0
tlv320aic3x-hifi
ads117x-hifi
root@beaglebone:/sys/kernel/debug/asoc# cat platforms
davinci-pcm-audio
snd-soc-dummy
root@beaglebone:/sys/kernel/debug/asoc#
 
If I now try to add this to snd_soc_dai_link, the kernel panics while booting:
{
                               .name = "ADS117X",
                               .stream_name = "ADS117X",
                               .cpu_dai_name = "davinci-mcasp.0",
                               .codec_dai_name = "ads117x-hifi",
                               .codec_name = "ads117x-codec",
                               .platform_name = "davinci-pcm-audio",
                               .init = evm_adsadc_init,
                               .ops = &evm_adc_ops,
}
 
Does anybody have an idea how it comes to this?
 
Another thing I don’t understand is, why do we register a platform in ads117.c?
static int __init ads117x_init(void)
{
               return platform_driver_register(&ads117x_codec_driver);
}
 
The old version used to register a snd_soc_dai_driver:
static int __init ads117x_modinit(void)
{
                return snd_soc_register_dai(&ads117x_dai);
}

An other way to solve this problem which I was thinking about: Is it possible to use the davinci-pcm-audio platform driver without a codec driver? The ADC doesn't have a control interface, so we probably could configure the mcasp and set a dummy codec?

Hi chrigima,

were you able to make the ADC work properly? Can you share the code?

Thanks a lot.