Re: [PATCHv6 2/4] iio: adc: exynos_adc: Control special clock of ADC to support Exynos3250 ADC

Arnd Bergmann
2014-07-18T09:48:53Z

On Friday 18 July 2014 14:59:44 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.

Do you know if any of the older ADC blocks have an "sclk" input as well?

Further, why is it called "sclk_adc" rather than just "sclk"?

> @@ -199,13 +262,20 @@ static void exynos_adc_v2_start_conv(struct exynos_adc *info,
> writel(con1 | ADC_CON_EN_START, ADC_V2_CON1(info->regs));
> }
>
> +#define __EXYNOS_ADC_V2_DATA \
> + .num_channels = MAX_ADC_V2_CHANNELS, \
> + .init_hw = exynos_adc_v2_init_hw, \
> + .exit_hw = exynos_adc_v2_exit_hw, \
> + .clear_irq = exynos_adc_v2_clear_irq, \
> + .start_conv = exynos_adc_v2_start_conv, \
> +
> static struct exynos_adc_data const exynos_adc_v2_data = {
> - .num_channels = MAX_ADC_V2_CHANNELS,
> + __EXYNOS_ADC_V2_DATA
> +};
>
> - .init_hw = exynos_adc_v2_init_hw,
> - .exit_hw = exynos_adc_v2_exit_hw,
> - .clear_irq = exynos_adc_v2_clear_irq,
> - .start_conv = exynos_adc_v2_start_conv,
> +static struct exynos_adc_data const exynos3250_adc_v2_data = {
> + __EXYNOS_ADC_V2_DATA
> + .needs_sclk = true,
> };

I think the macro hurts readability. Please just duplicate the definition
here.

> static const struct of_device_id exynos_adc_match[] = {
> @@ -215,6 +285,9 @@ static const struct of_device_id exynos_adc_match[] = {
> }, {
> .compatible = "samsung,exynos-adc-v2",
> .data = (void *)&exynos_adc_v2_data,
> + }, {
> + .compatible = "samsung,exynos3250-adc-v2",
> + .data = (void *)&exynos3250_adc_v2_data,
> },
> {},

Remove the '(void *)' cast here and mark the structure as 'const'.
We intentionally use a 'const void *' type here to verify that
the driver doesn't modify the per-device type data at runtime,
which would be bad if you ever have multiple device instances.

Arnd