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SubjectRe: [PATCH 1/7] add binding for stm32 multifunctions timer driver
2016-11-23 10:21 GMT+01:00 Lee Jones <lee.jones@linaro.org>:
> On Wed, 23 Nov 2016, Benjamin Gaignard wrote:
>
>> 2016-11-22 17:52 GMT+01:00 Lee Jones <lee.jones@linaro.org>:
>> > On Tue, 22 Nov 2016, Benjamin Gaignard wrote:
>> >
>> >> Add bindings information for stm32 timer MFD
>> >>
>> >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
>> >> ---
>> >> .../devicetree/bindings/mfd/stm32-timer.txt | 53 ++++++++++++++++++++++
>> >> 1 file changed, 53 insertions(+)
>> >> create mode 100644 Documentation/devicetree/bindings/mfd/stm32-timer.txt
>> >>
>> >> diff --git a/Documentation/devicetree/bindings/mfd/stm32-timer.txt b/Documentation/devicetree/bindings/mfd/stm32-timer.txt
>> >> new file mode 100644
>> >> index 0000000..3cefce1
>> >> --- /dev/null
>> >> +++ b/Documentation/devicetree/bindings/mfd/stm32-timer.txt
>> >> @@ -0,0 +1,53 @@
>> >> +STM32 multifunctions timer driver
>> >
>> > "STM32 Multi-Function Timer/PWM device bindings"
>> >
>> > Doesn't this shared device have a better name?
>>
>> In SoC documentation those hardware blocks are named "advanced-control
>> timers", "general purpose timers" or "basic timers"
>> "stm32-timer" name is already used for clock source driver, that why I
>> have prefix it with mfd
>
> MFD is a Linuxisum and has no place in hardware description.
>
> Please used one of the names you mentioned above.

I will go for "st,stm32-advanced-timer"

>
> Hopefully the one that best fits.
>
>> >> +stm32 timer MFD allow to handle at the same time pwm and IIO timer devices
>> >
>> > No need for this sentence.
>> >
>> OK
>>
>> >> +Required parameters:
>> >> +- compatible: must be one of the follow value:
>> >> + "st,stm32-mfd-timer1"
>> >> + "st,stm32-mfd-timer2"
>> >> + "st,stm32-mfd-timer3"
>> >> + "st,stm32-mfd-timer4"
>> >> + "st,stm32-mfd-timer5"
>> >> + "st,stm32-mfd-timer6"
>> >> + "st,stm32-mfd-timer7"
>> >> + "st,stm32-mfd-timer8"
>> >> + "st,stm32-mfd-timer9"
>> >> + "st,stm32-mfd-timer10"
>> >> + "st,stm32-mfd-timer11"
>> >> + "st,stm32-mfd-timer12"
>> >> + "st,stm32-mfd-timer13"
>> >> + "st,stm32-mfd-timer14"
>> >
>> > We don't normally number devices.
>> >
>> > What's stopping you from simply doing:
>> >
>> > pwm1: pwm1@40010000 {
>> > compatible = "st,stm32-pwm";
>> > };
>> > pwm2: pwm1@40020000 {
>> > compatible = "st,stm32-pwm";
>> > };
>> > pwm3: pwm1@40030000 {
>> > compatible = "st,stm32-pwm";
>> > };
>> >
>>
>> Because each instance of the hardware is slightly different: number of
>> pwm channels, triggers capabilities, etc ..
>> so I need to distinguish them.
>> Since it look to be a problem I will follow your suggestion and add a
>> property this driver to be able to identify each instance.
>> Do you think that "id" parameter (integer for 1 to 14) is acceptable ?
>
> Unfortunately not. IDs aren't allowed in DT.
>
> What about "pwm-chans" and "trigger"?
>
> pwm-chans : Number of available channels available

For pwm I need those 4 properties:
st,pwm-number: the number of PWM devices
st,complementary: if exist have complementary ouput
st,32bit-counter: if exist have 32 bits counter
st,breakinput-polarity: if set enable break input feature.

Is it acceptable from pwm maintainer point of view ?

> trigger : Boolean value specifying whether a timer is present

Following our discussion on IRC I will try to code for your proposal:

advanced-timer@40010000 {
compatible = "st,stm32-advanced-timer";
reg = <0x40010000 0x400>;
clocks = <&rcc 0 160>;
clock-names = "clk_int";

pwm@0 {
compatible = "st,stm32-pwm";
st,pwm-number= <4>;
st,complementary;
st,breakinput;
};

timer@0 {
reg = <1>;
compatible = "st,stm32-iio-timer";
interrupts = <27>;
triggers = <5 2 3 4>;
};
};

triggers parameter will be used to know which trigger are valid for
the IIO device

[snip]

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