Re: [PATCH 2/2] iio: adc: exynos_adc: Add support for S3C24xx ADC

Heiko Stübner
2014-07-22T10:43:09Z

Am Dienstag, 22. Juli 2014, 10:39:38 schrieb Arnd Bergmann:
> On Tuesday 22 July 2014 11:11:14 Chanwoo Choi wrote:
> > This patch add support for s3c2410/s3c2416/s3c2440/s3c2443 ADC. The
> > s3c24xx
> > is alomost same as ADCv1. But, There are a little difference as following:
> > - ADCMUX register address to select channel
> > - ADCDAT mask (10bit or 12bit ADC resolution according to SoC version)
>
> Very good, thanks for doing this patch!
>
> (adding Heiko to Cc, he's probably interested in seeing this as well.

indeed. Thanks for implementing this.

While trying to build a test setup for this, I noticed two points:

(1) I'm not sure what the second register (a "phy enable register" according
to the binding) is supposed to be.
According to binding and adc code it is mandatory, but I didn't find any
lone adc register in the s3c2416 manual.

(2) You might need something along the lines of:

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 11b048a..088c99a 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -129,7 +129,7 @@ config AT91_ADC

config EXYNOS_ADC
tristate "Exynos ADC driver support"
- depends on ARCH_EXYNOS || (OF && COMPILE_TEST)
+ depends on ARCH_EXYNOS || ARCH_S3C24XX || ARCH_S3C64XX || (OF && COMPILE_TEST)
help
Core support for the ADC block found in the Samsung EXYNOS series
of SoCs for drivers such as the touchscreen and hwmon to use to share

Thanks
Heiko

>
> One comment:
> > @@ -101,12 +107,14 @@ struct exynos_adc {
> >
> > struct completion completion;
> >
> > u32 value;
> >
> > + u32 value2;
> >
> > unsigned int version;
> >
> > };
> >
> > ...
> > @@ -365,7 +448,7 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
> >
> > ret = -ETIMEDOUT;
> >
> > } else {
> >
> > *val = info->value;
> >
> > - *val2 = 0;
> > + *val2 = info->value2;
> >
> > ret = IIO_VAL_INT;
> >
> > }
> >
> > @@ -377,9 +460,11 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
> >
> > static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
> > {
> >
> > struct exynos_adc *info = (struct exynos_adc *)dev_id;
> >
> > + u32 mask = info->data->mask;
> >
> > /* Read value */
> >
> > - info->value = readl(ADC_V1_DATX(info->regs)) & ADC_DATX_MASK;
> > + info->value = readl(ADC_V1_DATX(info->regs)) & mask;
> > + info->value2 = readl(ADC_V1_DATY(info->regs)) & mask;
> >
> > /* clear irq */
> > if (info->data->clear_irq)
>
> If I understand it right, this would only be necessary if we want
> to do the touchscreen driver as a separate iio client using the
> in-kernel interfaces. As Jonathan Cameron commented, we probably
> don't want to do that though. Even if we do, it should be a separate
> patch and not mixed in with the s3c24xx support.
>
> Aside from this:
>
> Acked-by: Arnd Bergmann <arnd@arndb.de>
>
> Arnd