Re: [PATCH v2 08/10] dt-bindings: connector: Add PCIe M.2 Mechanical Key E connector

[Rob Herring <robh@kernel.org>]

On Tue, Nov 25, 2025 at 08:15:12PM +0530, Manivannan Sadhasivam wrote:
> Add the devicetree binding for PCIe M.2 Mechanical Key E connector defined
> in the PCI Express M.2 Specification, r4.0, sec 5.1.2. This connector
> provides interfaces like PCIe or SDIO to attach the WiFi devices to the
> host machine, USB or UART+PCM interfaces to attach the Bluetooth (BT)
> devices along with additional interfaces like I2C for NFC solution. At any
> point of time, the connector can only support either PCIe or SDIO as the
> WiFi interface and USB or UART as the BT interface.

AFAICT, there's no muxing of interfaces. Maybe that's a defacto 
limitation on x86 systems? There's no reason to encode that into the 
binding if the pins aren't mux'ed on the connector.

> 
> The connector provides a primary power supply of 3.3v, along with an
> optional 1.8v VIO supply for the Adapter I/O buffer circuitry operating at
> 1.8v sideband signaling.
> 
> The connector also supplies optional signals in the form of GPIOs for fine
> grained power management.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> ---
>  .../bindings/connector/pcie-m2-e-connector.yaml    | 178 +++++++++++++++++++++
>  MAINTAINERS                                        |   1 +
>  2 files changed, 179 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml b/Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml
> new file mode 100644
> index 000000000000..fe2c9a943a21
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml
> @@ -0,0 +1,178 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/connector/pcie-m2-e-connector.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: PCIe M.2 Mechanical Key E Connector
> +
> +maintainers:
> +  - Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> +
> +description:
> +  A PCIe M.2 E connector node represents a physical PCIe M.2 Mechanical Key E
> +  connector. Mechanical Key E connectors are used to connect Wireless
> +  Connectivity devices including combinations of Wi-Fi, BT, NFC to the host
> +  machine over interfaces like PCIe/SDIO, USB/UART+PCM, and I2C.
> +
> +properties:
> +  compatible:
> +    const: pcie-m2-e-connector
> +
> +  vpcie3v3-supply:
> +    description: A phandle to the regulator for 3.3v supply.
> +
> +  vpcie1v8-supply:
> +    description: A phandle to the regulator for VIO 1.8v supply.
> +
> +  ports:
> +    $ref: /schemas/graph.yaml#/properties/ports
> +    description: OF graph bindings modeling the interfaces exposed on the
> +      connector. Since a single connector can have multiple interfaces, every
> +      interface has an assigned OF graph port number as described below.
> +
> +    properties:
> +      port@0:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description: Connector interfaces for Wi-Fi
> +
> +        properties:
> +          endpoint@0:
> +            $ref: /schemas/graph.yaml#/properties/endpoint
> +            description: PCIe interface
> +
> +          endpoint@1:
> +            $ref: /schemas/graph.yaml#/properties/endpoint
> +            description: SDIO interface
> +
> +        anyOf:
> +          - required:
> +              - endpoint@0
> +          - required:
> +              - endpoint@1
> +
> +      port@1:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description: Connector interfaces for BT
> +
> +        properties:
> +          endpoint@0:
> +            $ref: /schemas/graph.yaml#/properties/endpoint
> +            description: USB 2.0 interface
> +
> +          endpoint@1:
> +            $ref: /schemas/graph.yaml#/properties/endpoint
> +            description: UART interface
> +
> +        anyOf:
> +          - required:
> +              - endpoint@0
> +          - required:
> +              - endpoint@1
> +
> +      port@2:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description: PCM/I2S interface

Does this work with any existing DAI bindings? Or conflict with the 
audio graph card binding?

> +
> +      port@3:
> +        $ref: /schemas/graph.yaml#/properties/port
> +        description: I2C interface

Like the other one, use i2c-parent.

> +
> +    oneOf:
> +      - required:
> +          - port@0
> +
> +  clocks:
> +    description: 32.768 KHz Suspend Clock (SUSCLK) input from the host system to
> +      the M.2 card. Refer, PCI Express M.2 Specification r4.0, sec 3.1.12.1 for
> +      more details.
> +    maxItems: 1
> +
> +  w-disable1-gpios:
> +    description: GPIO controlled connection to W_DISABLE1# signal. This signal
> +      is used by the system to disable WiFi radio in the M.2 card. Refer, PCI
> +      Express M.2 Specification r4.0, sec 3.1.12.3 for more details.
> +    maxItems: 1
> +
> +  w-disable2-gpios:
> +    description: GPIO controlled connection to W_DISABLE2# signal. This signal
> +      is used by the system to disable BT radio in the M.2 card. Refer, PCI
> +      Express M.2 Specification r4.0, sec 3.1.12.3 for more details.
> +    maxItems: 1
> +
> +  viocfg-gpios:
> +    description: GPIO controlled connection to IO voltage configuration
> +      (VIO_CFG) signal. This signal is used by the M.2 card to indicate to the
> +      host system that the card supports an independent IO voltage domain for
> +      the sideband signals. Refer, PCI Express M.2 Specification r4.0, sec
> +      3.1.15.1 for more details.
> +    maxItems: 1
> +
> +  uim-power-src-gpios:
> +    description: GPIO controlled connection to UIM_POWER_SRC signal. This signal
> +      is used when the NFC solution is implemented and receives the power output
> +      from WWAN_UIM_PWR signal of the another WWAN M.2 card. Refer, PCI Express
> +      M.2 Specification r4.0, sec 3.1.11.1 for more details.
> +    maxItems: 1
> +
> +  uim-power-snk-gpios:
> +    description: GPIO controlled connection to UIM_POWER_SNK signal. This signal
> +      is used when the NFC solution is implemented and supplies power to the
> +      Universal Integrated Circuit Card (UICC). Refer, PCI Express M.2
> +      Specification r4.0, sec 3.1.11.2 for more details.
> +    maxItems: 1
> +
> +  uim-swp-gpios:
> +    description: GPIO controlled connection to UIM_SWP signal. This signal is
> +      used when the NFC solution is implemented and implements the Single Wire
> +      Protocol (SWP) interface to the UICC. Refer, PCI Express M.2 Specification
> +      r4.0, sec 3.1.11.3 for more details.
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - vpcie3v3-supply
> +
> +additionalProperties: false
> +
> +examples:
> +  # PCI M.2 Key E connector for Wi-Fi/BT with PCIe/UART interfaces
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    connector {
> +        compatible = "pcie-m2-e-connector";
> +        vpcie3v3-supply = <&vreg_wcn_3p3>;
> +        vpcie1v8-supply = <&vreg_l15b_1p8>;
> +        w-disable1-gpios = <&tlmm 117 GPIO_ACTIVE_LOW>;
> +        w-disable2-gpios = <&tlmm 116 GPIO_ACTIVE_LOW>;
> +
> +        ports {
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            port@0 {
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
> +                reg = <0>;
> +
> +                endpoint@0 {
> +                    reg = <0>;
> +                    remote-endpoint = <&pcie4_port0_ep>;
> +                };
> +            };
> +
> +            port@1 {
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
> +                reg = <1>;
> +
> +                endpoint@1 {
> +                    reg = <1>;
> +                    remote-endpoint = <&uart14_ep>;
> +                };
> +            };
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9b3f689d1f50..f707f29d0a37 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20478,6 +20478,7 @@ PCIE M.2 POWER SEQUENCING
>  M:	Manivannan Sadhasivam <mani@kernel.org>
>  L:	linux-pci@vger.kernel.org
>  S:	Maintained
> +F:	Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml
>  F:	Documentation/devicetree/bindings/connector/pcie-m2-m-connector.yaml
>  F:	drivers/power/sequencing/pwrseq-pcie-m2.c
>  
> 
> -- 
> 2.48.1
>