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SubjectRe: [PATCH v6 1/8] MFD: add bindings for STM32 Timers driver
On Tue, Dec 13, 2016 at 3:29 AM, Benjamin Gaignard
<benjamin.gaignard@linaro.org> wrote:
> 2016-12-12 19:51 GMT+01:00 Rob Herring <robh@kernel.org>:
>> On Fri, Dec 09, 2016 at 03:15:12PM +0100, Benjamin Gaignard wrote:
>>> Add bindings information for STM32 Timers
>>>
>>> version 6:
>>> - rename stm32-gtimer to stm32-timers
>>> - change compatible
>>> - add description about the IPs
>>>
>>> version 2:
>>> - rename stm32-mfd-timer to stm32-gptimer
>>> - only keep one compatible string
>>>
>>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
>>> ---
>>> .../devicetree/bindings/mfd/stm32-timers.txt | 46 ++++++++++++++++++++++
>>> 1 file changed, 46 insertions(+)
>>> create mode 100644 Documentation/devicetree/bindings/mfd/stm32-timers.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/mfd/stm32-timers.txt b/Documentation/devicetree/bindings/mfd/stm32-timers.txt
>>> new file mode 100644
>>> index 0000000..b30868e
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/mfd/stm32-timers.txt
>>> @@ -0,0 +1,46 @@
>>> +STM32 Timers driver bindings
>>> +
>>> +This IP provides 3 types of timer along with PWM functionality:
>>> +- advanced-control timers consist of a 16-bit auto-reload counter driven by a programmable
>>> + prescaler, break input feature, PWM outputs and complementary PWM ouputs channels.
>>> +- general-purpose timers consist of a 16-bit or 32-bit auto-reload counter driven by a
>>> + programmable prescaler and PWM outputs.
>>> +- basic timers consist of a 16-bit auto-reload counter driven by a programmable prescaler.
>>> +
>>> +Required parameters:
>>> +- compatible: must be "st,stm32-timers"
>>> +
>>> +- reg: Physical base address and length of the controller's
>>> + registers.
>>> +- clock-names: Set to "clk_int".
>>
>> 'clk' is redundant. Also, you don't really need -names when there is
>> only one of them.
>
> I use devm_regmap_init_mmio_clk() which get the clock by it name so
> I have to define it in DT.

Are you sure NULL is not allowed? I don't know, but at least clk_get()
allows NULL.

It's fine to keep, just drop the "clk_" part.

>
>>> +- clocks: Phandle to the clock used by the timer module.
>>> + For Clk properties, please refer to ../clock/clock-bindings.txt
>>> +
>>> +Optional parameters:
>>> +- resets: Phandle to the parent reset controller.
>>> + See ../reset/st,stm32-rcc.txt
>>> +
>>> +Optional subnodes:
>>> +- pwm: See ../pwm/pwm-stm32.txt
>>> +- timer: See ../iio/timer/stm32-timer-trigger.txt
>>> +
>>> +Example:
>>> + timers@40010000 {
>>> + #address-cells = <1>;
>>> + #size-cells = <0>;
>>> + compatible = "st,stm32-timers";
>>> + reg = <0x40010000 0x400>;
>>> + clocks = <&rcc 0 160>;
>>> + clock-names = "clk_int";
>>> +
>>> + pwm {
>>> + compatible = "st,stm32-pwm";
>>> + pinctrl-0 = <&pwm1_pins>;
>>> + pinctrl-names = "default";
>>> + };
>>> +
>>> + timer {
>>> + compatible = "st,stm32-timer-trigger";
>>> + reg = <0>;
>>
>> You don't need reg here as there is only one. In turn, you don't need
>> #address-cells or #size-cells.
>
> I use "reg" to set each timer configuration.
> From hardware point of view they are all the same except for which hardware
> signals they could consume and/or send.

This sounds okay, but...

> "reg" is used as index of the two tables in driver code.

this statement doesn't really sound like valid use of reg.

If you keep reg, then the node needs a unit address (timer@0).

Rob

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