[PATCH v7 05/15] dt-bindings: Document the STM32 reset bindings

[Maxime Coquelin]

2015-05-05 18:07 GMT+02:00 Daniel Thompson <daniel.thompson at linaro.org>:
> On 05/05/15 16:42, Philipp Zabel wrote:
>>
>> Am Dienstag, den 05.05.2015, 17:19 +0200 schrieb Maxime Coquelin:
>>>>>
>>>>> For example, includes/dt-bindings/mfd/stm32f4-rcc.h would look like:
>>>>>
>>>>> #define GPIOA 0
>>>>> #define GPIOB 1
>>>>> ...
>>>>> #define LTDC 186
>>
>>
>> That looks a bit fragile.
>> At least the defines for the indices should be properly namespaced,
>> check out include/dt-bindings/gpio/tegra-gpio.h for a similar case.
>
>
> Good point.
>
>>>>> #define STM32F4_RESET(x) (x + 128)
>>>>> #define STM32F4_CLOCK(x) (x + 384)
>
>
> Thinking more about this point, if we are going to follow hardware if might
> be better to have:
>
> #define STM32F4_RCC_AHB1_GPIOA 0
> #define STM32F4_RCC_AHB1_GPIOA 1
> ...
> #define STM32F4_RCC_APB2_LTDC 26
>
>
> #define STM32F4_AHB1_RESET(x) (STM32F4_RCC_AHB1_##x##_BIT + (0x10 * 8))
> #define STM32F4_AHB2_RESET(x) (STM32F4_RCC_AHB2_##x##_BIT + (0x14 * 8))
> ...
> #define STM32F4_APB2_RESET(x) (STM32F4_RCC_APB2_##x##_BIT + (0x24 * 8))
>
> Its more typing (or copy 'n pasting) by at least every number now maps
> directly to the datasheet.

As said in Philipp's reply, I like the idea.

Regards,
Maxime
>
>
>
>>>>>
>>>>> Then, in DT, a reset would be described like this:
>>>>>
>>>>> timer2 {
>>>>>       resets = <&rcc STM32F4_RESET(TIM2)>;
>>>>> };
>>>>>
>>>>> Phillip, Daniel, does that look acceptable to you?
>>>>
>>>>
>>>>
>>>> Doesn't look unreasonable.
>>>>
>>>> I am a little uneasy simply because there are very few similar header
>>>> files
>>>> in that directory but I haven't thought of a better idea.
>>>
>>>
>>> Since this file will be shared by both clock and reset drivers, I
>>> don't see better option.
>>> I will implement it in v8 if Philipp agrees.
>>
>>
>> Are the device tree maintainers happy with this idiom spreading?
>> Except for the point above, I think this is acceptable.
>>
>> regards
>> Philipp
>>
>