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 02:22, 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.

Best regards,
Tomasz