Subject: [PATCHv2 1/2] iio: adc: exynos_adc: Control special clock of ADC to support Exynos3250 ADC

From: [email-masked] (Chanwoo Choi)
Date: Wed, 16 Apr 2014 13:55:17 +0900

Hi Sachin,

On 04/16/2014 01:44 PM, Chanwoo Choi wrote:
> Hi Sachin,
> 
> On 04/16/2014 12:48 PM, Sachin Kamat wrote:
>> Hi Chanwoo,
>>
>> On 14 April 2014 14:37, Chanwoo Choi <[email-masked]> wrote:
>>> This patch control special clock for ADC in Exynos series's FSYS block.
>>> If special clock of ADC is registerd on clock list of common clk framework,
>>> Exynos ADC drvier have to control this clock.
>>>
>>> Exynos3250/Exynos4/Exynos5 has 'adc' clock as following:
>>> - 'adc' clock: bus clock for ADC
>>>
>>> Exynos3250 has additional 'sclk_tsadc' clock as following:
>>> - 'sclk_tsadc' clock: special clock for ADC which provide clock to internal ADC
>>>
>>> Exynos 4210/4212/4412 and Exynos5250/5420 has not included 'sclk_tsadc' clock
>>> in FSYS_BLK. But, Exynos3250 based on Cortex-A7 has only included 'sclk_tsadc'
>>> clock in FSYS_BLK.
>>>
>>> Cc: Jonathan Cameron <[email-masked]>
>>> Cc: Kukjin Kim <[email-masked]>
>>> Cc: Naveen Krishna Chatradhi
>>> Cc: linux-iio at vger.kernel.org
>>> Signed-off-by: Chanwoo Choi <[email-masked]>
>>> Acked-by: Kyungmin Park <[email-masked]>
>>> ---
>>>  drivers/iio/adc/exynos_adc.c | 54 +++++++++++++++++++++++++++++++++-----------
>>>  1 file changed, 41 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
>>> index d25b262..3c99243 100644
>>> --- a/drivers/iio/adc/exynos_adc.c
>>> +++ b/drivers/iio/adc/exynos_adc.c
>>> @@ -40,8 +40,9 @@
>>>  #include <linux/iio/driver.h>
>>>
>>>  enum adc_version {
>>> -       ADC_V1,
>>> -       ADC_V2
>>> +       ADC_V1 = 0x1,
>>> +       ADC_V2 = 0x2,
>>> +       ADC_V3 = (ADC_V1 | ADC_V2),
>>
>> Can't this be simply 0x3? Or is this not really a h/w version?
> 
> Even thought ADC_V3 isn't h/w revision, ADC_V3 include all featues of ADC_V2
> and only one difference of clock(sclk_tsadc) from ADC_V2.
> I want to describethat ADC_V3 include ADC_V2 feature So, I add as following:
> 	>> +       ADC_V3 = (ADC_V1 | ADC_V2),
> 
>>
>>>  };
>>>
>>>  /* EXYNOS4412/5250 ADC_V1 registers definitions */
>>> @@ -88,6 +89,7 @@ struct exynos_adc {
>>>         void __iomem            *regs;
>>>         void __iomem            *enable_reg;
>>>         struct clk              *clk;
>>> +       struct clk              *sclk;
>>>         unsigned int            irq;
>>>         struct regulator        *vdd;
>>>
>>> @@ -100,6 +102,7 @@ struct exynos_adc {
>>>  static const struct of_device_id exynos_adc_match[] = {
>>>         { .compatible = "samsung,exynos-adc-v1", .data = (void *)ADC_V1 },
>>>         { .compatible = "samsung,exynos-adc-v2", .data = (void *)ADC_V2 },
>>> +       { .compatible = "samsung,exynos-adc-v3", .data = (void *)ADC_V3 },
>>>         {},
>>>  };
>>>  MODULE_DEVICE_TABLE(of, exynos_adc_match);
>>> @@ -128,7 +131,7 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
>>>         mutex_lock(&indio_dev->mlock);
>>>
>>>         /* Select the channel to be used and Trigger conversion */
>>> -       if (info->version == ADC_V2) {
>>> +       if (info->version & ADC_V2) {
>>
>> So, now this would be applicable for ADC_V3 too, right?

ADC_V3 isn't h/w version. So, I think this code is proper instead of using ADC_V3 direclty.
I want to use ADC_V3 version on checking clock(sclk_tsadc).

>>
>>
>>>                 con2 = readl(ADC_V2_CON2(info->regs));
>>>                 con2 &= ~ADC_V2_CON2_ACH_MASK;
>>>                 con2 |= ADC_V2_CON2_ACH_SEL(chan->address);
>>> @@ -165,7 +168,7 @@ static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
>>>         info->value = readl(ADC_V1_DATX(info->regs)) &
>>>                                                 ADC_DATX_MASK;
>>>         /* clear irq */
>>> -       if (info->version == ADC_V2)
>>> +       if (info->version & ADC_V2)
>>>                 writel(1, ADC_V2_INT_ST(info->regs));
>>>         else
>>>                 writel(1, ADC_V1_INTCLR(info->regs));
>>> @@ -226,11 +229,25 @@ static int exynos_adc_remove_devices(struct device *dev, void *c)
>>>         return 0;
>>>  }
>>>
>>> +static void exynos_adc_enable_clock(struct exynos_adc *info, bool enable)
>>> +{
>>> +       if (enable) {
>>> +               clk_prepare_enable(info->clk);
>>
>> This could fail. Is it OK without any checks?
> 
> OK, I'll check return value.

Do you want to check return value always?
I think again, Some device drivers in mainline would not check
return value of clock function. If maintainer confirm this modification,
I'll fix it as your comment.

Best Regards,
Chanwoo Choi