Re: [PATCHv4 2/4] iio: adc: exynos_adc: Control special clock of ADC to support Exynos3250 ADC

[Tomasz Figa <tomasz.figa@gmail.com>]

On 20.06.2014 02:28, Chanwoo Choi wrote:
> On 06/20/2014 09:24 AM, Tomasz Figa wrote:
>> On 20.06.2014 02:22, Chanwoo Choi wrote:
>>> Hi Tomasz,
>>>
>>> On 06/18/2014 04:58 PM, Tomasz Figa wrote:
>>>> Hi Chanwoo,
>>>>
>>>> On 18.06.2014 04:20, Chanwoo Choi 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_adc' clock as following:
>>>>> - 'sclk_adc' clock: special clock for ADC which provide clock to internal ADC
>>>>>
>>>>> Exynos 4210/4212/4412 and Exynos5250/5420 has not included 'sclk_adc' clock
>>>>> in FSYS_BLK. But, Exynos3250 based on Cortex-A7 has only included 'sclk_adc'
>>>>> clock in FSYS_BLK.
>>>>>
>>>>> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
>>>>> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
>>>>> ---
>>>>>  drivers/iio/adc/exynos_adc.c | 93 ++++++++++++++++++++++++++++++++++++++------
>>>>>  1 file changed, 81 insertions(+), 12 deletions(-)
>>>>>
>>>>> diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
>>>>> index c30def6..6b026ac 100644
>>>>> --- a/drivers/iio/adc/exynos_adc.c
>>>>> +++ b/drivers/iio/adc/exynos_adc.c
>>>>> @@ -41,7 +41,8 @@
>>>>>  
>>>>>  enum adc_version {
>>>>>  	ADC_V1,
>>>>> -	ADC_V2
>>>>> +	ADC_V2,
>>>>> +	ADC_V2_EXYNOS3250,
>>>>>  };
>>>>>  
>>>>>  /* EXYNOS4412/5250 ADC_V1 registers definitions */
>>>>> @@ -85,9 +86,11 @@ enum adc_version {
>>>>>  #define EXYNOS_ADC_TIMEOUT	(msecs_to_jiffies(100))
>>>>>  
>>>>>  struct exynos_adc {
>>>>> +	struct device		*dev;
>>>>>  	void __iomem		*regs;
>>>>>  	void __iomem		*enable_reg;
>>>>>  	struct clk		*clk;
>>>>> +	struct clk		*sclk;
>>>>>  	unsigned int		irq;
>>>>>  	struct regulator	*vdd;
>>>>>  	struct exynos_adc_ops	*ops;
>>>>> @@ -96,6 +99,7 @@ struct exynos_adc {
>>>>>  
>>>>>  	u32			value;
>>>>>  	unsigned int            version;
>>>>> +	bool			needs_sclk;
>>>>
>>>> This should be rather a part of the variant struct. See my comments to
>>>> patch 1/4.
>>>
>>> OK, I'll include 'needs_sclk' in "variant" structure.
>>>
>>>>
>>>>>  };
>>>>>  
>>>>>  struct exynos_adc_ops {
>>>>> @@ -103,11 +107,21 @@ struct exynos_adc_ops {
>>>>>  	void (*clear_irq)(struct exynos_adc *info);
>>>>>  	void (*start_conv)(struct exynos_adc *info, unsigned long addr);
>>>>>  	void (*stop_conv)(struct exynos_adc *info);
>>>>> +	void (*disable_clk)(struct exynos_adc *info);
>>>>> +	int (*enable_clk)(struct exynos_adc *info);
>>>>>  };
>>>>>  
>>>>>  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-v1",
>>>>> +		.data = (void *)ADC_V1,
>>>>> +	}, {
>>>>> +		.compatible = "samsung,exynos-adc-v2",
>>>>> +		.data = (void *)ADC_V2,
>>>>> +	}, {
>>>>> +		.compatible = "samsung,exynos3250-adc-v2",
>>>>> +		.data = (void *)ADC_V2_EXYNOS3250,
>>>>> +	},
>>>>>  	{},
>>>>>  };
>>>>>  MODULE_DEVICE_TABLE(of, exynos_adc_match);
>>>>> @@ -156,11 +170,42 @@ static void exynos_adc_v1_stop_conv(struct exynos_adc *info)
>>>>>  	writel(con, ADC_V1_CON(info->regs));
>>>>>  }
>>>>>  
>>>>> +static void exynos_adc_disable_clk(struct exynos_adc *info)
>>>>> +{
>>>>> +	if (info->needs_sclk)
>>>>> +		clk_disable_unprepare(info->sclk);
>>>>> +	clk_disable_unprepare(info->clk);
>>>>> +}
>>>>> +
>>>>> +static int exynos_adc_enable_clk(struct exynos_adc *info)
>>>>> +{
>>>>> +	int ret;
>>>>> +
>>>>> +	ret = clk_prepare_enable(info->clk);
>>>>> +	if (ret) {
>>>>> +		dev_err(info->dev, "failed enabling adc clock: %d\n", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>> +	if (info->needs_sclk) {
>>>>> +		ret = clk_prepare_enable(info->sclk);
>>>>> +		if (ret) {
>>>>> +			clk_disable_unprepare(info->clk);
>>>>> +			dev_err(info->dev,
>>>>> +				"failed enabling sclk_tsadc clock: %d\n", ret);
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>  static struct exynos_adc_ops exynos_adc_v1_ops = {
>>>>>  	.init_hw	= exynos_adc_v1_init_hw,
>>>>>  	.clear_irq	= exynos_adc_v1_clear_irq,
>>>>>  	.start_conv	= exynos_adc_v1_start_conv,
>>>>>  	.stop_conv	= exynos_adc_v1_stop_conv,
>>>>> +	.disable_clk	= exynos_adc_disable_clk,
>>>>> +	.enable_clk	= exynos_adc_enable_clk,
>>>>>  };
>>>>>  
>>>>>  static void exynos_adc_v2_init_hw(struct exynos_adc *info)
>>>>> @@ -210,6 +255,8 @@ static struct exynos_adc_ops exynos_adc_v2_ops = {
>>>>>  	.start_conv	= exynos_adc_v2_start_conv,
>>>>>  	.clear_irq	= exynos_adc_v2_clear_irq,
>>>>>  	.stop_conv	= exynos_adc_v2_stop_conv,
>>>>> +	.disable_clk	= exynos_adc_disable_clk,
>>>>> +	.enable_clk	= exynos_adc_enable_clk,
>>>>
>>>> Based on the fact that all variants use the same function, I don't think
>>>> there is a reason to add .{disable,enable}_clk in the ops struct. If
>>>> they diverge in future, they could be added later, but right now it
>>>> doesn't have any value.
>>>
>>> OK, I'll not add .{disable,enable}_clk and then just use following functions for clock control:
>>> - exynos_adc_prepare_clk() : once execute this function in _probe()
>>> - exynos_adc_unprepare_clk() : once execute this function in _remove()
>>> - exynos_adc_enable_clk()
>>> - exynos_adc_disable_clk()
>>
>> Is there any need to separate prepare/unprepare from enable/disable?
>> Otherwise sounds good, thanks.
> 
> Naveen Krishna Chatradhi want to execute once prepare/unpreare in probe/remove function.
> 
> - Following comment of Naveen Krishna Chatradhi
>> +static void exynos_adc_disable_clk(struct exynos_adc *info)
>> +{
>> +       if (info->needs_sclk)
>> +               clk_disable_unprepare(info->sclk);
>> +       clk_disable_unprepare(info->clk);
> 
> (Just a nit pick) As a part of cleanup can we also change to use
> clk_disable() here and clk_unprepare() once and for all at the end.
> 
>> +}
>> +
>> +static int exynos_adc_enable_clk(struct exynos_adc *info)
>> +{
>> +       int ret;
>> +
>> +       ret = clk_prepare_enable(info->clk);
>> +       if (ret) {
>> +               dev_err(info->dev, "failed enabling adc clock: %d\n", ret);
>> +               return ret;
>> +       }
>> +
>> +       if (info->needs_sclk) {
>> +               ret = clk_prepare_enable(info->sclk);
> Can we use clk_enable() here and clk_prepare() some where during the probe.

I still don't see any reason to do it. Naveen, what's the motivation for
this change? For me, it only complicates the code, without any added value.

Best regards,
Tomasz