Re: [PATCH v2 3/3] dt-bindings: leds: servo-pwm: Add new bindings for servo-pwm

Rob Herring
2023-02-17T23:23:36Z

On Fri, Feb 17, 2023 at 03:57:30PM +0100, Angelo Compagnucci wrote:
> This binding describes the binding for controlling servo motors through
> pwm.
>
> Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
> ---
> .../devicetree/bindings/misc/servo-pwm.yaml | 59 +++++++++++++++++++
> MAINTAINERS | 1 +
> 2 files changed, 60 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/misc/servo-pwm.yaml
>
> diff --git a/Documentation/devicetree/bindings/misc/servo-pwm.yaml b/Documentation/devicetree/bindings/misc/servo-pwm.yaml
> new file mode 100644
> index 000000000000..faa8d4734817
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/servo-pwm.yaml
> @@ -0,0 +1,59 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/misc/servo-pwm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Servo motor connected to PWM
> +
> +maintainers:
> + - Angelo Compagnucci <angelo@amarulasolutions.com>
> +
> +description:
> + Each servo is represented as a servo-pwm device.
> + The 20ms period is the accepted standard and so most of the motors
> + support it, while the positioning min/max duty cycle or the motor
> + degrees aperture vary lot between manufacturers.
> + The most common type of servo (SG90) has 180 degrees of movement
> + and moves between 0.5ms and 2.5ms duty cycle.
> +
> +properties:
> + compatible:
> + const: servo-pwm
> +
> +patternProperties:
> + properties:
> + pwms:
> + maxItems: 1
> +
> + pwm-names: true

Drop. '-names' is for when there is more than 1.
> +
> + degrees:

Kind of vague: servo-degrees

> + description:
> + How many degrees the motor can move.
> + $ref: /schemas/types.yaml#/definitions/uint32

0-2^32 are valid degrees?

> +
> + duty-min:
> + description:
> + Duty cycle for position the motor at 0 degrees.

Units are ms? percent? Use standard unit suffix.

> + $ref: /schemas/types.yaml#/definitions/uint32
> +
> + duty-max:
> + description:
> + Duty cycle for positioning the motor at "degrees" angle.
> + $ref: /schemas/types.yaml#/definitions/uint32
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> +
> + servo: servo@0 {
> + compatible = "servo-pwm";
> + pwms = <&pwm 0 20000000 0>;
> + degrees = <180>;
> + duty-min = <500000>;
> + duty-max = <2500000>;
> + };
> +
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 356daea0861d..8f41daee62fc 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8742,6 +8742,7 @@ M: "Angelo Compagnucci" <angelo@amarulasolutions.com>
> L: linux-pwm@vger.kernel.org
> S: Maintained
> F: Documentation/ABI/testing/sysfs-driver-servo-pwm
> +F: Documentation/devicetree/bindings/misc/servo-pwm.yaml
> F: drivers/misc/servo-pwm.c
>
> GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER
> --
> 2.34.1
>