linux-kernel - Re: [PATCH] iio: adc: exynos_adc: Add support for ADCv3 on exynos7

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Date:	Fri, 31 Oct 2014 19:31:46 +0530
From:	Abhilash Kesavan <kesavan.abhilash@...il.com>
To:	Chanwoo Choi <cw00.choi@...sung.com>
Cc:	linux-iio@...r.kernel.org, jic23@...nel.org,
	Naveen Krishna <naveenkrishna.ch@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: adc: exynos_adc: Add support for ADCv3 on exynos7

Hi Chanwoo,

Thanks for the quick response.

On Fri, Oct 31, 2014 at 6:17 PM, Chanwoo Choi <cw00.choi@...sung.com> wrote:
> Hi Abhilash,
>
> On 10/31/2014 09:38 PM, Abhilash Kesavan wrote:
>> The ADC on exynos7 is quite similar to ADCv2. The differences are as
>> follows:
>>       - v3 has 8 input channels (10 in v2).
>>       - v3 does not include an ADC PHY control register.
>>       - Some ADC_CON2 register bits being used in v2 are listed as
>>         reserved in v3. This results in a different init_hw function
>>         for v3.
>>
>> Signed-off-by: Abhilash Kesavan <a.kesavan@...sung.com>
>> ---
>> - Based on Naveen's "iio: exynos-adc: use syscon instead of ioremap" patchset
>> http://comments.gmane.org/gmane.linux.kernel.iio/13943
>>
>>  .../devicetree/bindings/arm/samsung/exynos-adc.txt |    2 ++
>>  drivers/iio/adc/exynos_adc.c                       |   32 ++++++++++++++++++++
>>  2 files changed, 34 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
>> index c368210..a11e32c 100644
>> --- a/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
>> +++ b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt
>> @@ -14,6 +14,8 @@ Required properties:
>>                               for exynos4412/5250 and s5pv210 controllers.
>>                       Must be "samsung,exynos-adc-v2" for
>>                               future controllers.
>> +                     Must be "samsung,exynos-adc-v3" for
>> +                             the ADC in Exynos7 and compatibles
>
> I prefer to use 'exynos7-adc' instead of 'exynos-adc-v3'.
> Exynos7 has little different from existing ADCv2.

Sure, I'll change it. The reason for my choosing v3 was that reading
the version register (0x20 offset) showed a value of 0x80000009 in
Exynos7 as against 0x80000008 in both 5420 and 3250.
>
> Also, If you want to use 'exynos-adc-v3' compatible,
> Exynos7's TRM have to include the correct version(v3) infromation.

I could not see any mention of the ADC controller version in the
Exynos7 UM other than the version register. Does that mean it is v2 ?

Regards,
Abhilash
>
> Thanks,
> Chanwoo Choi
>
>
>
>>                       Must be "samsung,exynos3250-adc" for
>>                               controllers compatible with ADC of Exynos3250.
>>                       Must be "samsung,s3c2410-adc" for
>> diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
>> index fe03177..74d0a9d 100644
>> --- a/drivers/iio/adc/exynos_adc.c
>> +++ b/drivers/iio/adc/exynos_adc.c
>> @@ -390,6 +390,35 @@ static const struct exynos_adc_data exynos3250_adc_data = {
>>       .start_conv     = exynos_adc_v2_start_conv,
>>  };
>>
>> +static void exynos_adc_v3_init_hw(struct exynos_adc *info)
>> +{
>> +     u32 con1, con2;
>> +
>> +     if (info->data->needs_adc_phy)
>> +             regmap_write(info->pmu_map, info->data->phy_offset, 1);
>> +
>> +     con1 = ADC_V2_CON1_SOFT_RESET;
>> +     writel(con1, ADC_V2_CON1(info->regs));
>> +
>> +     con2 = readl(ADC_V2_CON2(info->regs));
>> +     con2 &= ~ADC_V2_CON2_C_TIME(7);
>> +     con2 |= ADC_V2_CON2_C_TIME(0);
>> +     writel(con2, ADC_V2_CON2(info->regs));
>> +
>> +     /* Enable interrupts */
>> +     writel(1, ADC_V2_INT_EN(info->regs));
>> +}
>> +
>> +static const struct exynos_adc_data exynos_adc_v3_data = {
>> +     .num_channels   = MAX_ADC_V1_CHANNELS,
>> +     .mask           = ADC_DATX_MASK, /* 12 bit ADC resolution */
>> +
>> +     .init_hw        = exynos_adc_v3_init_hw,
>> +     .exit_hw        = exynos_adc_v2_exit_hw,
>> +     .clear_irq      = exynos_adc_v2_clear_irq,
>> +     .start_conv     = exynos_adc_v2_start_conv,
>> +};
>> +
>>  static const struct of_device_id exynos_adc_match[] = {
>>       {
>>               .compatible = "samsung,s3c2410-adc",
>> @@ -413,6 +442,9 @@ static const struct of_device_id exynos_adc_match[] = {
>>               .compatible = "samsung,exynos-adc-v2",
>>               .data = &exynos_adc_v2_data,
>>       }, {
>> +             .compatible = "samsung,exynos-adc-v3",
>> +             .data = &exynos_adc_v3_data,
>> +     }, {
>>               .compatible = "samsung,exynos3250-adc",
>>               .data = &exynos3250_adc_data,
>>       },
>>
>
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