Inspired by pwn-trigger, create a new binding for using a GPIO
pin as a trigger source.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v5 Changes:
* New patch in v5.
---
 .../bindings/trigger-source/gpio-trigger.yaml | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml

diff --git a/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
new file mode 100644
index 000000000000..d77d62050179
--- /dev/null
+++ b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/trigger-source/gpio-trigger.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic trigger source using GPIO
+
+description: Remaps a GPIO pin as a trigger source.
+
+maintainers:
+  - Jonathan Santos <Jonathan.Santos@analog.com>
+
+properties:
+  compatible:
+    const: gpio-trigger
+
+  '#trigger-source-cells':
+    const: 0
+
+  gpios:
+    maxItems: 1
+    description: GPIO to be used as a trigger source.
+
+required:
+  - compatible
+  - '#trigger-source-cells'
+  - gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    trigger {
+        compatible = "gpio-trigger";
+        #trigger-source-cells = <0>;
+        gpios = <&gpio1 15 GPIO_ACTIVE_HIGH>;
+    };
-- 
2.34.1

Hi Jonathan,

thanks for your patch!

On Fri, Apr 11, 2025 at 5:56 PM Jonathan Santos
<Jonathan.Santos@analog.com> wrote:

> Inspired by pwn-trigger, create a new binding for using a GPIO
> pin as a trigger source.
>
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>

Is this actually documenting the trigger sources I implemented for LED
here?
https://lore.kernel.org/all/20230926-gpio-led-trigger-dt-v2-0-e06e458b788e@linaro.org/

Then maybe put this in as Link:

I tried to figure out how to properly document it but I think it was part of
dtsschema and that may have confused me.

> +title: Generic trigger source using GPIO
> +
> +description: Remaps a GPIO pin as a trigger source.

Please write "GPIO line" instead of "GPIO pin".

The reason is that not all GPIOs are pins. Some are other stuff.

Yours,
Linus Walleij

On 4/16/25 2:43 AM, Linus Walleij wrote:
> Hi Jonathan,
> 
> thanks for your patch!
> 
> On Fri, Apr 11, 2025 at 5:56 PM Jonathan Santos
> <Jonathan.Santos@analog.com> wrote:
> 
>> Inspired by pwn-trigger, create a new binding for using a GPIO
>> pin as a trigger source.
>>
>> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> 
> Is this actually documenting the trigger sources I implemented for LED
> here?
> https://lore.kernel.org/all/20230926-gpio-led-trigger-dt-v2-0-e06e458b788e@linaro.org/

No. This is something more like "pwm-clock" where it is converting a gpios
phandle to a trigger-sources phandle. Doing it this way comes from some
discussion on using trigger-sources for the SPI offload stuff I was working
on recently. [1]

As a result of that work, there are generic bindings for trigger-sources and
#trigger-source cells in dtschma now that can be used by any node. [2]

The way the leds subsystem does it where you can have trigger-sources = <&gpio 0>
or <&ohci_port1> directly has the issue where it isn't easy for the consumer
to know what type of node the provider is. Effectively, we have to have the
linux,default-trigger property to tell us what the provider node type is. By
adding this extra node in between we can get that type info more naturally than
the linux-specific property. And each subsystem won't have to have extra code
added for trigger-sources like you had to add for gpios.

[1]: https://lore.kernel.org/all/20241031-croon-boss-3b30ff9e9333@spud/
[2]: https://github.com/devicetree-org/dt-schema/commit/93ee8008959e362548168eaa7bdc20c115f3d586

On 4/11/25 10:56 AM, Jonathan Santos wrote:
> Inspired by pwn-trigger, create a new binding for using a GPIO

s/pwn/pwm/

> pin as a trigger source.
>

On Fri, Apr 11, 2025 at 12:56:04PM -0300, Jonathan Santos wrote:
> Inspired by pwn-trigger, create a new binding for using a GPIO
> pin as a trigger source.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> v5 Changes:
> * New patch in v5.
> ---
>  .../bindings/trigger-source/gpio-trigger.yaml | 40 +++++++++++++++++++
>  1 file changed, 40 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
> 
> diff --git a/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
> new file mode 100644
> index 000000000000..d77d62050179
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
> @@ -0,0 +1,40 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/trigger-source/gpio-trigger.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Generic trigger source using GPIO
> +

> +description: Remaps a GPIO pin as a trigger source.

Just a minor comment about the description, "remaps" is a very software
term, I think you can just say "A GPIO used as a trigger source" and be
fine.

> +
> +maintainers:
> +  - Jonathan Santos <Jonathan.Santos@analog.com>
> +
> +properties:
> +  compatible:
> +    const: gpio-trigger
> +
> +  '#trigger-source-cells':
> +    const: 0
> +
> +  gpios:
> +    maxItems: 1
> +    description: GPIO to be used as a trigger source.
> +
> +required:
> +  - compatible
> +  - '#trigger-source-cells'
> +  - gpios
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    trigger {
> +        compatible = "gpio-trigger";
> +        #trigger-source-cells = <0>;
> +        gpios = <&gpio1 15 GPIO_ACTIVE_HIGH>;
> +    };
> -- 
> 2.34.1
>