Re: [PATCH v5 3/6] dt-bindings: input: Document Microsoft G6 Touch Digitizer

[Rob Herring <robh@kernel.org>]

On Thu, Jul 07, 2022 at 09:58:59AM -0700, Jarrett Schultz wrote:
> From: Jarrett Schultz <jaschultz@microsoft.com>
> 
> Documentation describes the required and optional properties for
> implementing Device Tree for a Microsoft G6 Touch Digitizer that
> supports HID over SPI Protocol 1.0 specification.
> 
> Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>
> ---
>  .../input/microsoft,g6-touch-digitizer.yaml   | 135 ++++++++++++++++++
>  1 file changed, 135 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/microsoft,g6-touch-digitizer.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/microsoft,g6-touch-digitizer.yaml b/Documentation/devicetree/bindings/input/microsoft,g6-touch-digitizer.yaml
> new file mode 100644
> index 000000000000..b607bbb32a42
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/microsoft,g6-touch-digitizer.yaml
> @@ -0,0 +1,135 @@
> +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/microsoft,g6-touch-digitizer.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Microsoft G6 Touch Digitizer
> +
> +maintainers:
> +  - Dmitry Antipov <dmanti@microsoft.com>
> +
> +description: |
> +  Microsoft G6 touch digitizer is a HID over SPI device supporting HID Over SPI
> +  Protocol Specification 1.0, available at
> +  https://www.microsoft.com/en-us/download/details.aspx?id=103325.
> +
> +properties:
> +  compatible:
> +    items:
> +      - const: microsoft,g6-touch-digitizer
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  reset-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO specifier for the digitizer's reset pin (active low). The line must
> +      be flagged with GPIO_ACTIVE_LOW.
> +
> +  vdd-supply:
> +    description:
> +      Regulator for the VDD supply voltage.
> +
> +  input-report-header-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 16777215

0xffffff would be more readable IMO.

> +    description:
> +      A value to be included in the Read Approval packet, listing an address of
> +      the input report header to be put on the SPI bus. This address has 24
> +      bits.
> +
> +  input-report-body-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 16777215
> +    description:
> +      A value to be included in the Read Approval packet, listing an address of
> +      the input report body to be put on the SPI bus. This address has 24 bits.
> +
> +  output-report-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 16777215
> +    description:
> +      A value to be included in the Output Report sent by the host, listing an
> +      address where the output report on the SPI bus is to be written to. This
> +      address has 24 bits.

Are all these properties common to HID-over-SPI or all of HID? If so, 
then they should be in a common, shared schema doc and referenced here.

> +
> +  post-power-on-delay-ms:
> +    description:
> +      Optional time in ms required by the device after enabling its regulators
> +      or powering it on, before it is ready for communication.
> +
> +  minimal-reset-delay-ms:
> +    description:
> +      Optional minimum amount of time in ms that device needs to be in reset
> +      state for the reset to take effect.

These delays should really be implied by the compatible string.

> +
> +  read-opcode:
> +    description: 
> +      Value to be used in Read Approval packets. 1 byte.

Needs a type reference.

> +
> +  write-opcode:
> +    description:
> +      Value to be used in Write Approval packets. 1 byte.

ditto

> +
> +  hid-over-spi-flags:
> +    description:
> +      16 bits.
> +      Bits 0-12 - Reserved (must be 0)
> +      Bit 13 - SPI Write Mode. Possible values -
> +        * 0b0- Writes are carried out in Single-SPI mode
> +        * 0b1- Writes are carried out in the Multi-SPI mode specified by bits
> +               14-15
> +      Bits 14-15 - Multi-SPI Mode. Possible values - 
> +        * 0b00- Single SPI
> +        * 0b01- Dual SPI
> +        * 0b10- Quad SPI

ditto.

The existing SPI bus width properties wouldn't work here?

> +
> +required:
> +  - compatible
> +  - interrupts
> +  - reset-gpios
> +  - vdd-supply
> +  - input-report-header-address
> +  - input-report-body-address
> +  - output-report-address
> +  - read-opcode
> +  - write-opcode
> +  - hid-over-spi-flags
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    spi {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      hid@0 {
> +        compatible = "microsoft,g6-touch-digitizer";
> +        reg = <0x0>;
> +        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
> +        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> +        vdd-supply = <&pm8350c_l3>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&ts_d6_reset_assert &ts_d6_int_bias>;
> +        input-report-header-address = <0x1000>;
> +        input-report-body-address = <0x1004>;
> +        output-report-address = <0x2000>;
> +        read-opcode = <0x0b>;
> +        write-opcode = <0x02>;

Description says 8-bit, but this is 32-bits.

> +        hid-over-spi-flags = <0x00>;

Description says 16-bits, but this is 32-bits.

> +        post-power-on-delay-ms = <5>;
> +        minimal-reset-delay-ms = <5>;
> +      };
> +    };
> -- 
> 2.25.1
> 
>