Re: [PATCH v4 5/9] dt-bindings: connector: Add PCIe M.2 Mechanical Key E connector

Rob Herring
2026-01-13T17:14:25Z

On Mon, Jan 12, 2026 at 09:56:04PM +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. Spec also provides an optional interface to connect the UIM card,
> but that is not covered in this binding.
>
> 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 | 154 +++++++++++++++++++++
> MAINTAINERS | 1 +
> 2 files changed, 155 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..b65b39ddfd19
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml
> @@ -0,0 +1,154 @@
> +# 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.

I don't see any 1.8V supply on the connector. There are 1.8V IOs and you
may need something in DT to ensure those are powered. However, there's
no guarantee that it's a single 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

I think I already said this, but multiple endpoints are generally for
something that's muxed. Looking at the connector pinout, PCIe and SDIO
are not muxed. So these 2 should be 2 port nodes.

> +
> + 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

And UART and USB are not muxed either.

> +
> + anyOf:
> + - required:
> + - endpoint@0
> + - required:
> + - endpoint@1
> +
> + port@2:
> + $ref: /schemas/graph.yaml#/properties/port
> + description: PCM/I2S interface
> +
> + i2c-parent:
> + $ref: /schemas/types.yaml#/definitions/phandle
> + description: I2C interface

Move out of 'ports'.

> +
> + 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 input 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 input to W_DISABLE2# 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
> +
> + viocfg-gpios:
> + description: GPIO output 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

What about SDIO and UART WAKE, SDIO RESET, and vendor defined signals?

> +
> +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 {
> + reg = <0>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + endpoint@0 {
> + reg = <0>;
> + remote-endpoint = <&pcie4_port0_ep>;
> + };
> + };
> +
> + port@1 {
> + reg = <1>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + endpoint@1 {
> + reg = <1>;
> + remote-endpoint = <&uart14_ep>;
> + };
> + };
> + };
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2eb7b6d26573..451c54675b24 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20795,6 +20795,7 @@ 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
>