Add the dt binding for the Kinetic KTD2801 backlight driver.

Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
---
 .../bindings/leds/backlight/kinetic,ktd2801.yaml   | 46 ++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml b/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml
new file mode 100644
index 000000000000..970d54bac18e
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/kinetic,ktd2801.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Kinetic Technologies KTD2801 one-wire backlight
+
+maintainers:
+  - Duje Mihanović <duje.mihanovic@skole.hr>
+
+description: |
+  The Kinetic Technologies KTD2801 is a LED backlight driver controlled
+  by a single GPIO line. The driver can be controlled with a PWM signal
+  or by pulsing the GPIO line to set the backlight level. This is called
+  "ExpressWire".
+
+allOf:
+  - $ref: common.yaml#
+
+properties:
+  compatible:
+    const: kinetic,ktd2801
+
+  enable-gpios:
+    maxItems: 1
+
+  default-brightness: true
+  max-brightness: true
+
+required:
+  - compatible
+  - enable-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    backlight {
+        compatible = "kinetic,ktd2801";
+        enable-gpios = <&gpio 97 GPIO_ACTIVE_LOW>;
+        max-brightness = <210>;
+        default-brightness = <100>;
+    };

-- 
2.42.0

On Thu, Oct 05, 2023 at 08:49:08PM +0200, Duje Mihanović wrote:
> Add the dt binding for the Kinetic KTD2801 backlight driver.
>
> Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
> ---
>  .../bindings/leds/backlight/kinetic,ktd2801.yaml   | 46 ++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml b/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml
> new file mode 100644
> index 000000000000..970d54bac18e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml
> @@ -0,0 +1,46 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/kinetic,ktd2801.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Kinetic Technologies KTD2801 one-wire backlight
> +
> +maintainers:
> +  - Duje Mihanović <duje.mihanovic@skole.hr>
> +
> +description: |
> +  The Kinetic Technologies KTD2801 is a LED backlight driver controlled
> +  by a single GPIO line. The driver can be controlled with a PWM signal
> +  or by pulsing the GPIO line to set the backlight level. This is called
> +  "ExpressWire".
> +
> +allOf:
> +  - $ref: common.yaml#
> +
> +properties:
> +  compatible:
> +    const: kinetic,ktd2801
> +
> +  enable-gpios:
> +    maxItems: 1

Why "enable"? This is the line we are going to us to bitbang the
ExpressWire protocol. Doesn't that make it a control or data pin?


Daniel.

On Friday, October 6, 2023 2:30:14 PM CEST Daniel Thompson wrote:
> On Thu, Oct 05, 2023 at 08:49:08PM +0200, Duje Mihanović wrote:
> > +  enable-gpios:
> > +    maxItems: 1
> 
> Why "enable"? This is the line we are going to us to bitbang the
> ExpressWire protocol. Doesn't that make it a control or data pin?

I named it "enable" because the KTD253 driver does so too, but also because 
that pin is also used to power down the IC. If "enable" isn't right 
regardless, is just "gpios" fine for this?

Regards,
Duje

On Fri, Oct 06, 2023 at 03:08:42PM +0200, Duje Mihanović wrote:
> On Friday, October 6, 2023 2:30:14 PM CEST Daniel Thompson wrote:
> > On Thu, Oct 05, 2023 at 08:49:08PM +0200, Duje Mihanović wrote:
> > > +  enable-gpios:
> > > +    maxItems: 1
> >
> > Why "enable"? This is the line we are going to us to bitbang the
> > ExpressWire protocol. Doesn't that make it a control or data pin?
>
> I named it "enable" because the KTD253 driver does so too, but also because
> that pin is also used to power down the IC. If "enable" isn't right
> regardless, is just "gpios" fine for this?

KTD2692 implements ExpressWire and calls this signal ctrl-gpios. I'd
suggest copying that prior art for now.


Daniel.

On 05/10/2023 20:49, Duje Mihanović wrote:
> Add the dt binding for the Kinetic KTD2801 backlight driver.
> 
> Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
> ---
>  .../bindings/leds/backlight/kinetic,ktd2801.yaml   | 46 ++++++++++++++++++++++
>  1 file changed, 46 insertions(+)


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof