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[PATCH 0/5] Add EXTI GPIO trigger support to STM32 ADC

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  [PATCH 0/5] Add EXTI GPIO trigger support to STM32 ADC Fabrice Gasnier <fabrice.gasnier@st.com> - 2017-01-30 15:30 +0100
    [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger Fabrice Gasnier <fabrice.gasnier@st.com> - 2017-01-30 15:50 +0100
      Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger Rob Herring <robh@kernel.org> - 2017-02-01 17:40 +0100
        Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger Fabrice Gasnier <fabrice.gasnier@st.com> - 2017-02-02 10:30 +0100
          Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger Rob Herring <robh@kernel.org> - 2017-02-02 16:50 +0100
            Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger Fabrice Gasnier <fabrice.gasnier@st.com> - 2017-02-03 11:40 +0100
      Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger Linus Walleij <linus.walleij@linaro.org> - 2017-02-03 20:20 +0100
    [PATCH 2/5] iio: adc: stm32: add dt option to set default trigger polarity Fabrice Gasnier <fabrice.gasnier@st.com> - 2017-01-30 16:40 +0100

#1569776 — [PATCH 0/5] Add EXTI GPIO trigger support to STM32 ADC

STM32 ADC, can use GPIOs configured as EXTI line (external interrupt)
as trigger source for conversions.
This patchset is based on latest IIO testing branch, and adds support
for EXTi GPIO triggers in IIO.
It also adds a dt option to configure default trigger polarity in
STM32 ADC driver.

Fabrice Gasnier (5):
  Documentation: dt: iio: document stm32 adc trigger polarity
  iio: adc: stm32: add dt option to set default trigger polarity
  Documentation: dt: iio: document stm32 exti trigger
  iio: trigger: add support for STM32 EXTI triggers
  iio: adc: stm32: add exti11 gpio trigger source

 .../devicetree/bindings/iio/adc/st,stm32-adc.txt   |   3 +
 .../bindings/iio/trigger/st,stm32-exti-trigger.txt |  17 +++
 drivers/iio/adc/stm32-adc.c                        |  14 +++
 drivers/iio/trigger/Kconfig                        |  10 ++
 drivers/iio/trigger/Makefile                       |   1 +
 drivers/iio/trigger/stm32-exti-trigger.c           | 124 +++++++++++++++++++++
 include/linux/iio/trigger/stm32-exti-trigger.h     |  26 +++++
 7 files changed, 195 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
 create mode 100644 drivers/iio/trigger/stm32-exti-trigger.c
 create mode 100644 include/linux/iio/trigger/stm32-exti-trigger.h

-- 
1.9.1

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#1569791 — [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger

Add dt documentation for st,stm32-exti-trigger.
EXTi gpio signal can be routed internally as trigger source for various
IPs (e.g. for ADC or DAC conversions).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 .../bindings/iio/trigger/st,stm32-exti-trigger.txt      | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt

diff --git a/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
new file mode 100644
index 0000000..ebf2645
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
@@ -0,0 +1,17 @@
+STMicroelectronics STM32 EXTI trigger bindings
+
+EXTi gpio signal can be routed internally as trigger source for various
+IPs (e.g. for ADC or DAC conversions).
+
+Contents of a stm32 exti trigger root node:
+-------------------------------------------
+Required properties:
+- compatible: Should be "st,stm32-exti-trigger"
+- extiN-gpio: optional gpio line that may be used as external trigger source
+  (e.g. N may be 0..15. For example, exti11-gpio can trig ADC on stm32f4).
+
+Example:
+	triggers {
+		compatible = "st,stm32-exti-trigger";
+		exti11-gpio=<&gpioa 11 0>;
+	};
-- 
1.9.1

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#1571715 — Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger

On Mon, Jan 30, 2017 at 02:57:41PM +0100, Fabrice Gasnier wrote:
> Add dt documentation for st,stm32-exti-trigger.
> EXTi gpio signal can be routed internally as trigger source for various

s/gpio/GPIO/

> IPs (e.g. for ADC or DAC conversions).

Please use "dt-bindings: iio:" for the subject prefix.

> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
>  .../bindings/iio/trigger/st,stm32-exti-trigger.txt      | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
> new file mode 100644
> index 0000000..ebf2645
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
> @@ -0,0 +1,17 @@
> +STMicroelectronics STM32 EXTI trigger bindings
> +
> +EXTi gpio signal can be routed internally as trigger source for various

s/gpio/GPIO/

> +IPs (e.g. for ADC or DAC conversions).
> +
> +Contents of a stm32 exti trigger root node:

Drop "root"

> +-------------------------------------------
> +Required properties:
> +- compatible: Should be "st,stm32-exti-trigger"

This whole binding looks a bit suspicious. Is this actually a h/w block? 
What makes it stm32 specific? Seems like the gpio properties should just 
be part of the ADC or DAC that they trigger.

> +- extiN-gpio: optional gpio line that may be used as external trigger source

-gpios is the preferred form.

> +  (e.g. N may be 0..15. For example, exti11-gpio can trig ADC on stm32f4).
> +
> +Example:
> +	triggers {
> +		compatible = "st,stm32-exti-trigger";
> +		exti11-gpio=<&gpioa 11 0>;

spaces around the "=".

> +	};
> -- 
> 1.9.1
> 

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#1572218 — Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger

On 02/01/2017 05:35 PM, Rob Herring wrote:
> On Mon, Jan 30, 2017 at 02:57:41PM +0100, Fabrice Gasnier wrote:
>> Add dt documentation for st,stm32-exti-trigger.
>> EXTi gpio signal can be routed internally as trigger source for various
>
> s/gpio/GPIO/
>
>> IPs (e.g. for ADC or DAC conversions).
>
> Please use "dt-bindings: iio:" for the subject prefix.

Hi Rob,

I'll fix this in V2.

>
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>> ---
>>  .../bindings/iio/trigger/st,stm32-exti-trigger.txt      | 17 +++++++++++++++++
>>  1 file changed, 17 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>
>> diff --git a/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>> new file mode 100644
>> index 0000000..ebf2645
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>> @@ -0,0 +1,17 @@
>> +STMicroelectronics STM32 EXTI trigger bindings
>> +
>> +EXTi gpio signal can be routed internally as trigger source for various
>
> s/gpio/GPIO/
>
>> +IPs (e.g. for ADC or DAC conversions).
>> +
>> +Contents of a stm32 exti trigger root node:
>
> Drop "root"
I'll fix these in V2.

>
>> +-------------------------------------------
>> +Required properties:
>> +- compatible: Should be "st,stm32-exti-trigger"
>
> This whole binding looks a bit suspicious. Is this actually a h/w block?
> What makes it stm32 specific? Seems like the gpio properties should just
> be part of the ADC or DAC that they trigger.

Please let me explain in more details.
I think best is I add following documentation in binding. Something like:

GPIO + EXTI controller side | ADC side (input trigger MUX, same for DAC)
                             |
        IIO trigger         --->         IIO device
                             |                  __________
                             |          inX  --|          \
                             |          ...  --|  SAR ADC  |-->
         __                  |         __      |__________/
PA11 --|  \                 | TIMx --|  \   trigger   ^
PB11 --|   |                  ...  --|   }----------->'
...  --|   }---- EXTI11 ---------->--|__/
      --|   |                |
PJ11 --|__/                 |

In fact, this driver configures GPIO and EXTI controllers (left side of
above scheme), and it registers corresponding trigger in IIO. Then it 
can be used by other IPs registered as IIO devices.

I think this should be outside of ADC or DAC IIO device drivers, to live 
in separate IIO trigger driver. It will avoid duplicating code (e.g. 
PATCH 4) into several IIO device drivers.

Is it ok to declare this as separate IIO trigger driver?
Maybe Jonathan could also advise on this ?

As I see it, this is stm32 specific, as any GPIO bank, (e.g. PA11,
PB11...) can be selected to generate (EXTI11) hardware trigger signal.

>
>> +- extiN-gpio: optional gpio line that may be used as external trigger source
>
> -gpios is the preferred form.

I apologize, I didn't make it clear in the first place. Please let me 
rephrase. Is bellow description more suitable ?

- extiN-gpio: One or several named GPIO lines that may be used as
   external trigger source by STM32 ADC, DAC. N may be 0..15.
   For example, on stm32f4, exti11-gpio can trig ADC, exti9-gpio can
   trig DAC.

>
>> +  (e.g. N may be 0..15. For example, exti11-gpio can trig ADC on stm32f4).
>> +
>> +Example:
>> +	triggers {
>> +		compatible = "st,stm32-exti-trigger";
>> +		exti11-gpio=<&gpioa 11 0>;
>
> spaces around the "=".
I'll fix it in V2, and also add example for more that one EXTI trigger:

	triggers {
		compatible = "st,stm32-exti-trigger";
		exti9-gpio = <&gpioa 9 0>;
		exti11-gpio = <&gpioa 11 0>;
		...
	};

Above binding can typically be used in board dt, in case on-board gpio 
is connected/used as trigger source for IIO device (STM32 ADC/DAC).

Please let me know if this clarifies, so I'll do necessary changes in V2.

Many thanks for your review.
Best Regards,
Fabrice

>
>> +	};
>> --
>> 1.9.1
>>

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#1572483 — Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger

+Linus W

On Thu, Feb 2, 2017 at 3:19 AM, Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
> On 02/01/2017 05:35 PM, Rob Herring wrote:
>>
>> On Mon, Jan 30, 2017 at 02:57:41PM +0100, Fabrice Gasnier wrote:
>>>
>>> Add dt documentation for st,stm32-exti-trigger.
>>> EXTi gpio signal can be routed internally as trigger source for various
>>
>>
>> s/gpio/GPIO/
>>
>>> IPs (e.g. for ADC or DAC conversions).
>>
>>
>> Please use "dt-bindings: iio:" for the subject prefix.
>
>
> Hi Rob,
>
> I'll fix this in V2.
>
>>
>>>
>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>>> ---
>>>  .../bindings/iio/trigger/st,stm32-exti-trigger.txt      | 17
>>> +++++++++++++++++
>>>  1 file changed, 17 insertions(+)
>>>  create mode 100644
>>> Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>> b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>> new file mode 100644
>>> index 0000000..ebf2645
>>> --- /dev/null
>>> +++
>>> b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>> @@ -0,0 +1,17 @@
>>> +STMicroelectronics STM32 EXTI trigger bindings
>>> +
>>> +EXTi gpio signal can be routed internally as trigger source for various
>>
>>
>> s/gpio/GPIO/
>>
>>> +IPs (e.g. for ADC or DAC conversions).
>>> +
>>> +Contents of a stm32 exti trigger root node:
>>
>>
>> Drop "root"
>
> I'll fix these in V2.
>
>>
>>> +-------------------------------------------
>>> +Required properties:
>>> +- compatible: Should be "st,stm32-exti-trigger"
>>
>>
>> This whole binding looks a bit suspicious. Is this actually a h/w block?
>> What makes it stm32 specific? Seems like the gpio properties should just
>> be part of the ADC or DAC that they trigger.
>
>
> Please let me explain in more details.
> I think best is I add following documentation in binding. Something like:
>
> GPIO + EXTI controller side | ADC side (input trigger MUX, same for DAC)
>                             |
>        IIO trigger         --->         IIO device
>                             |                  __________
>                             |          inX  --|          \
>                             |          ...  --|  SAR ADC  |-->
>         __                  |         __      |__________/
> PA11 --|  \                 | TIMx --|  \   trigger   ^
> PB11 --|   |                  ...  --|   }----------->'
> ...  --|   }---- EXTI11 ---------->--|__/
>      --|   |                |
> PJ11 --|__/                 |
>
> In fact, this driver configures GPIO and EXTI controllers (left side of
> above scheme), and it registers corresponding trigger in IIO. Then it can be
> used by other IPs registered as IIO devices.
>
> I think this should be outside of ADC or DAC IIO device drivers, to live in
> separate IIO trigger driver. It will avoid duplicating code (e.g. PATCH 4)
> into several IIO device drivers.
>
> Is it ok to declare this as separate IIO trigger driver?

Drivers and DT nodes are not necessarily 1 to 1.

What controls the GPIO line that is used for the trigger?

> Maybe Jonathan could also advise on this ?
>
> As I see it, this is stm32 specific, as any GPIO bank, (e.g. PA11,
> PB11...) can be selected to generate (EXTI11) hardware trigger signal.

This seems more like a pinmux'ing issue than a GPIO. This isn't really
a GPIO if it is routed to a h/w control.

A -gpios property for a trigger would make sense if you had a driver
handling GPIO interrupts to generate IIO triggers. This seems to be
just mux control.

>>> +- extiN-gpio: optional gpio line that may be used as external trigger
>>> source
>>
>>
>> -gpios is the preferred form.
>
>
> I apologize, I didn't make it clear in the first place. Please let me
> rephrase. Is bellow description more suitable ?

What I mean is the property name is wrong. It should be "extiN-gpios".

>
> - extiN-gpio: One or several named GPIO lines that may be used as
>   external trigger source by STM32 ADC, DAC. N may be 0..15.
>   For example, on stm32f4, exti11-gpio can trig ADC, exti9-gpio can
>   trig DAC.
>
>>
>>> +  (e.g. N may be 0..15. For example, exti11-gpio can trig ADC on
>>> stm32f4).
>>> +
>>> +Example:
>>> +       triggers {
>>> +               compatible = "st,stm32-exti-trigger";
>>> +               exti11-gpio=<&gpioa 11 0>;
>>
>>
>> spaces around the "=".
>
> I'll fix it in V2, and also add example for more that one EXTI trigger:
>
>         triggers {
>                 compatible = "st,stm32-exti-trigger";
>                 exti9-gpio = <&gpioa 9 0>;
>                 exti11-gpio = <&gpioa 11 0>;
>                 ...
>         };
>
> Above binding can typically be used in board dt, in case on-board gpio is
> connected/used as trigger source for IIO device (STM32 ADC/DAC).
>
> Please let me know if this clarifies, so I'll do necessary changes in V2.
>
> Many thanks for your review.
> Best Regards,
> Fabrice
>
>>
>>> +       };
>>> --
>>> 1.9.1
>>>
>

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#1573020 — Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger

On 02/02/2017 04:45 PM, Rob Herring wrote:
> +Linus W
>
> On Thu, Feb 2, 2017 at 3:19 AM, Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
>> On 02/01/2017 05:35 PM, Rob Herring wrote:
>>>
>>> On Mon, Jan 30, 2017 at 02:57:41PM +0100, Fabrice Gasnier wrote:
>>>>
>>>> Add dt documentation for st,stm32-exti-trigger.
>>>> EXTi gpio signal can be routed internally as trigger source for various
>>>
>>>
>>> s/gpio/GPIO/
>>>
>>>> IPs (e.g. for ADC or DAC conversions).
>>>
>>>
>>> Please use "dt-bindings: iio:" for the subject prefix.
>>
>>
>> Hi Rob,
>>
>> I'll fix this in V2.
>>
>>>
>>>>
>>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
>>>> ---
>>>>  .../bindings/iio/trigger/st,stm32-exti-trigger.txt      | 17
>>>> +++++++++++++++++
>>>>  1 file changed, 17 insertions(+)
>>>>  create mode 100644
>>>> Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>>>
>>>> diff --git
>>>> a/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>>> b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>>> new file mode 100644
>>>> index 0000000..ebf2645
>>>> --- /dev/null
>>>> +++
>>>> b/Documentation/devicetree/bindings/iio/trigger/st,stm32-exti-trigger.txt
>>>> @@ -0,0 +1,17 @@
>>>> +STMicroelectronics STM32 EXTI trigger bindings
>>>> +
>>>> +EXTi gpio signal can be routed internally as trigger source for various
>>>
>>>
>>> s/gpio/GPIO/
>>>
>>>> +IPs (e.g. for ADC or DAC conversions).
>>>> +
>>>> +Contents of a stm32 exti trigger root node:
>>>
>>>
>>> Drop "root"
>>
>> I'll fix these in V2.
>>
>>>
>>>> +-------------------------------------------
>>>> +Required properties:
>>>> +- compatible: Should be "st,stm32-exti-trigger"
>>>
>>>
>>> This whole binding looks a bit suspicious. Is this actually a h/w block?
>>> What makes it stm32 specific? Seems like the gpio properties should just
>>> be part of the ADC or DAC that they trigger.
>>
>>
>> Please let me explain in more details.
>> I think best is I add following documentation in binding. Something like:
>>
>> GPIO + EXTI controller side | ADC side (input trigger MUX, same for DAC)
>>                             |
>>        IIO trigger         --->         IIO device
>>                             |                  __________
>>                             |          inX  --|          \
>>                             |          ...  --|  SAR ADC  |-->
>>         __                  |         __      |__________/
>> PA11 --|  \                 | TIMx --|  \   trigger   ^
>> PB11 --|   |                  ...  --|   }----------->'
>> ...  --|   }---- EXTI11 ---------->--|__/
>>      --|   |                |
>> PJ11 --|__/                 |
>>
>> In fact, this driver configures GPIO and EXTI controllers (left side of
>> above scheme), and it registers corresponding trigger in IIO. Then it can be
>> used by other IPs registered as IIO devices.
>>
>> I think this should be outside of ADC or DAC IIO device drivers, to live in
>> separate IIO trigger driver. It will avoid duplicating code (e.g. PATCH 4)
>> into several IIO device drivers.
>>
>> Is it ok to declare this as separate IIO trigger driver?
>
> Drivers and DT nodes are not necessarily 1 to 1.
Hi Rob,

Sorry, I don't get it. Can you clarify ?

>
> What controls the GPIO line that is used for the trigger?

This can be anything connected to GPIO line, such as (on board)
push-button, external synchronization signal ...

>
>> Maybe Jonathan could also advise on this ?
>>
>> As I see it, this is stm32 specific, as any GPIO bank, (e.g. PA11,
>> PB11...) can be selected to generate (EXTI11) hardware trigger signal.
>
> This seems more like a pinmux'ing issue than a GPIO. This isn't really
> a GPIO if it is routed to a h/w control.

Sorry, muxing part (e.g. PA11, PB11...) isn't shown in above scheme.
GPIO is muxed via gpio/pinctrl driver.

>
> A -gpios property for a trigger would make sense if you had a driver
> handling GPIO interrupts to generate IIO triggers. This seems to be
> just mux control.

This is almost it, there are two stages.
- trigger starts conversion on device (e.g. ADC...) by hardware (no need 
for interrupt on 1st stage, data isn't ready anyway).
- 2nd stage, end of conversion polls the trigger.

Just to summarize, rephrase, in case push button is used to trigger 
conversions:
- 1st declare GPIO (to which push button is connected)
- GPIO is muxed into external interrupt (e.g. EXTI) by using pinctrl
and exti driver. This may be compared to a 'gpio_keys' up to this point.
- EXTI line is able to either generate an interrupt (not used here)
and/or start conversion as trigger line (that is used here).
- end of conversion does the actual trigger poll.

>
>>>> +- extiN-gpio: optional gpio line that may be used as external trigger
>>>> source
>>>
>>>
>>> -gpios is the preferred form.
>>
>>
>> I apologize, I didn't make it clear in the first place. Please let me
>> rephrase. Is bellow description more suitable ?
>
> What I mean is the property name is wrong. It should be "extiN-gpios".
Oh... got it, thanks.
I'll update this.

Best Regards,
Fabrice
>
>>
>> - extiN-gpio: One or several named GPIO lines that may be used as
>>   external trigger source by STM32 ADC, DAC. N may be 0..15.
>>   For example, on stm32f4, exti11-gpio can trig ADC, exti9-gpio can
>>   trig DAC.
>>
>>>
>>>> +  (e.g. N may be 0..15. For example, exti11-gpio can trig ADC on
>>>> stm32f4).
>>>> +
>>>> +Example:
>>>> +       triggers {
>>>> +               compatible = "st,stm32-exti-trigger";
>>>> +               exti11-gpio=<&gpioa 11 0>;
>>>
>>>
>>> spaces around the "=".
>>
>> I'll fix it in V2, and also add example for more that one EXTI trigger:
>>
>>         triggers {
>>                 compatible = "st,stm32-exti-trigger";
>>                 exti9-gpio = <&gpioa 9 0>;
>>                 exti11-gpio = <&gpioa 11 0>;
>>                 ...
>>         };
>>
>> Above binding can typically be used in board dt, in case on-board gpio is
>> connected/used as trigger source for IIO device (STM32 ADC/DAC).
>>
>> Please let me know if this clarifies, so I'll do necessary changes in V2.
>>
>> Many thanks for your review.
>> Best Regards,
>> Fabrice
>>
>>>
>>>> +       };
>>>> --
>>>> 1.9.1
>>>>
>>

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#1573383 — Re: [PATCH 3/5] Documentation: dt: iio: document stm32 exti trigger

On Mon, Jan 30, 2017 at 2:57 PM, Fabrice Gasnier <fabrice.gasnier@st.com> wrote:

> Add dt documentation for st,stm32-exti-trigger.
> EXTi gpio signal can be routed internally as trigger source for various
> IPs (e.g. for ADC or DAC conversions).

And you say this is done using pin control, elsewhere in the conversation
if I understand it correctly?

> +Contents of a stm32 exti trigger root node:
> +-------------------------------------------
> +Required properties:
> +- compatible: Should be "st,stm32-exti-trigger"
> +- extiN-gpio: optional gpio line that may be used as external trigger source
> +  (e.g. N may be 0..15. For example, exti11-gpio can trig ADC on stm32f4).
> +
> +Example:
> +       triggers {
> +               compatible = "st,stm32-exti-trigger";
> +               exti11-gpio=<&gpioa 11 0>;
> +       };

So what I do not understand i if this has any stm32-specific behaviour at all,
so that compatible-string has any meaning.

Should we not rather define compatible = "gpio-trigger"; to be used by
everyone? Especially for the device tree?

If it's "mostly generic, a bit specific too" it should likely be:

compatible = "gpio-trigger", "st,stm32-exit-trigger";

Yours,
Linus Walleij

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#1569840 — [PATCH 2/5] iio: adc: stm32: add dt option to set default trigger polarity

STM32 ADC trigger polarity can be set to either rising, falling
or both edges. Add dt option to configure it.
Note: default value may be overridden later via trigger_polarity
sysfs attribute.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/iio/adc/stm32-adc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 9b49a6ad..be0e457 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -997,6 +997,13 @@ static int stm32_adc_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	of_property_read_u32(pdev->dev.of_node, "st,trigger-polarity",
+			     &adc->trigger_polarity);
+	if (adc->trigger_polarity >= ARRAY_SIZE(stm32_trig_pol_items)) {
+		dev_err(&pdev->dev, "Invalid st,trigger-polarity property\n");
+		return -EINVAL;
+	}
+
 	adc->irq = platform_get_irq(pdev, 0);
 	if (adc->irq < 0) {
 		dev_err(&pdev->dev, "failed to get irq\n");
-- 
1.9.1

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