Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema
From: Rob Herring
Date: Tue Mar 03 2026 - 09:01:44 EST
On Tue, Mar 3, 2026 at 12:14 AM Jingyuan Liang <jingyliang@xxxxxxxxxxxx> wrote:
>
> 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.
>
> The properties are common to HID over SPI.
>
> Signed-off-by: Dmitry Antipov <dmanti@xxxxxxxxxxxxx>
> Signed-off-by: Jarrett Schultz <jaschultz@xxxxxxxxxxxxx>
> Signed-off-by: Jingyuan Liang <jingyliang@xxxxxxxxxxxx>
> ---
> .../devicetree/bindings/input/hid-over-spi.yaml | 153 +++++++++++++++++++++
> 1 file changed, 153 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/input/hid-over-spi.yaml b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> new file mode 100644
> index 000000000000..b623629ed9d3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> @@ -0,0 +1,153 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/hid-over-spi.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: HID over SPI Devices
> +
> +maintainers:
> + - Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> + - Jiri Kosina <jkosina@xxxxxxx>
> +
> +description: |+
> + HID over SPI provides support for various Human Interface Devices over the
> + SPI bus. These devices can be for example touchpads, keyboards, touch screens
> + or sensors.
> +
> + The specification has been written by Microsoft and is currently available here:
> + https://www.microsoft.com/en-us/download/details.aspx?id=103325
> +
> + If this binding is used, the kernel module spi-hid will handle the communication
> + with the device and the generic hid core layer will handle the protocol.
> +
> +allOf:
> + - $ref: /schemas/input/touchscreen/touchscreen.yaml#
> +
> +properties:
> + compatible:
> + oneOf:
> + - items:
> + - enum:
> + - microsoft,g6-touch-digitizer
> + - const: hid-over-spi
> + - description: Just "hid-over-spi" alone is allowed, but not recommended.
> + const: hid-over-spi
> +
> + 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.
Is this part of the spec? This won't scale for multiple devices with
different power rails.
> +
> + input-report-header-address:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + minimum: 0
> + maximum: 0xffffff
> + 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: 0xffffff
> + 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: 0xffffff
> + 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.
> +
> + 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.
Drop. This should be implied by the compatible.
> +
> + 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.
Drop. This should be implied by the compatible.
> +
> + read-opcode:
> + $ref: /schemas/types.yaml#/definitions/uint8
> + description:
> + Value to be used in Read Approval packets. 1 byte.
> +
> + write-opcode:
> + $ref: /schemas/types.yaml#/definitions/uint8
> + description:
> + Value to be used in Write Approval packets. 1 byte.
Why are these and the address properties above not defined by the
spec? Do they vary for a specific device? If not, then they should be
implied by the compatible.
> +
> + hid-over-spi-flags:
> + $ref: /schemas/types.yaml#/definitions/uint16
> + 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
We already have SPI properties to define the bus width for read and write.
> +
> +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 = "hid-over-spi";
> + 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>;
> + hid-over-spi-flags = <0x0000>;
> + post-power-on-delay-ms = <5>;
> + minimal-reset-delay-ms = <5>;
> + };
> + };
> \ No newline at end of file
Fix this.
Rob