Re: [PATCH 1/5] dt-bindings: PCI: Add STM32MP25 PCIe root complex bindings

[Rob Herring <robh@kernel.org>]

On Tue, Nov 12, 2024 at 05:19:21PM +0100, Christian Bruel wrote:
> Document the bindings for STM32MP25 PCIe Controller configured in
> root complex mode.
> Supports 4 legacy interrupts and MSI interrupts from the ARM
> GICv2m controller.
> 
> Allow tuning to change payload (default 128B) thanks to the
> st,max-payload-size entry.
> Can also limit the Maximum Read Request Size on downstream devices to the
> minimum possible value between 128B and 256B.
> 
> STM32 PCIE may be in a power domain which is the case for the STM32MP25
> based boards.
> Supports wake# from wake-gpios
> 
> Signed-off-by: Christian Bruel <christian.bruel@foss.st.com>
> ---
>  .../bindings/pci/st,stm32-pcie-host.yaml      | 149 ++++++++++++++++++
>  1 file changed, 149 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pci/st,stm32-pcie-host.yaml
> 
> diff --git a/Documentation/devicetree/bindings/pci/st,stm32-pcie-host.yaml b/Documentation/devicetree/bindings/pci/st,stm32-pcie-host.yaml
> new file mode 100644
> index 000000000000..d7d360b63a08
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pci/st,stm32-pcie-host.yaml
> @@ -0,0 +1,149 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pci/st,stm32-pcie-host.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: STM32MP25 PCIe root complex driver
> +
> +maintainers:
> +  - Christian Bruel <christian.bruel@foss.st.com>
> +
> +description:
> +  PCIe root complex controller based on the Synopsys DesignWare PCIe core.
> +
> +select:
> +  properties:
> +    compatible:
> +      const: st,stm32mp25-pcie-rc
> +  required:
> +    - compatible
> +
> +allOf:
> +  - $ref: /schemas/pci/pci-host-bridge.yaml#
> +  - $ref: /schemas/pci/snps,dw-pcie-common.yaml#

snps,dw-pcie.yaml instead of these 2.

> +
> +properties:
> +  compatible:
> +    const: st,stm32mp25-pcie-rc
> +
> +  reg:
> +    items:
> +      - description: Data Bus Interface (DBI) registers.
> +      - description: PCIe configuration registers.
> +
> +  reg-names:
> +    items:
> +      - const: dbi
> +      - const: config
> +
> +  resets:
> +    maxItems: 1
> +
> +  reset-names:
> +    const: core

-names with a single entry is kind of pointless.

> +
> +  clocks:
> +    maxItems: 1
> +    description: PCIe system clock
> +
> +  clock-names:
> +    const: core
> +
> +  phys:
> +    maxItems: 1
> +
> +  phy-names:
> +    const: pcie-phy
> +
> +  num-lanes:
> +    const: 1
> +
> +  msi-parent:
> +    maxItems: 1

Just 'msi-parent: true'. It's already only ever 1 entry.

> +
> +  reset-gpios:
> +    description: GPIO controlled connection to PERST# signal
> +    maxItems: 1
> +
> +  wake-gpios:
> +    description: GPIO controlled connection to WAKE# input signal
> +    maxItems: 1
> +

> +  st,limit-mrrs:
> +    description: If present limit downstream MRRS to 256B
> +    type: boolean
> +
> +  st,max-payload-size:
> +    description: Maximum Payload size to use
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [128, 256]
> +    default: 128

IIRC, other hosts have similar restrictions, so you should be able to do 
the same and imply it from the compatible. Though I'm open to a common 
property as Bjorn suggested.

> +
> +  wakeup-source: true
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  access-controllers:
> +    maxItems: 1
> +
> +if:
> +  required:
> +    - wakeup-source
> +then:
> +  required:
> +    - wake-gpios

This can be just:

dependentRequired:
  wakeup-source: [ wake-gpios ]

(dependentRequired supercedes dependencies)

> +
> +required:
> +  - interrupt-map
> +  - interrupt-map-mask
> +  - ranges
> +  - resets
> +  - reset-names
> +  - clocks
> +  - clock-names
> +  - phys
> +  - phy-names
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/st,stm32mp25-rcc.h>
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/phy/phy.h>
> +    #include <dt-bindings/reset/st,stm32mp25-rcc.h>
> +
> +    pcie@48400000 {
> +        compatible = "st,stm32mp25-pcie-rc";
> +        device_type = "pci";
> +        num-lanes = <1>;
> +        reg = <0x48400000 0x400000>,
> +              <0x10000000 0x10000>;
> +        reg-names = "dbi", "config";
> +        #interrupt-cells = <1>;
> +        interrupt-map-mask = <0 0 0 7>;
> +        interrupt-map = <0 0 0 1 &intc 0 0 GIC_SPI 264 IRQ_TYPE_LEVEL_HIGH>,
> +                        <0 0 0 2 &intc 0 0 GIC_SPI 265 IRQ_TYPE_LEVEL_HIGH>,
> +                        <0 0 0 3 &intc 0 0 GIC_SPI 266 IRQ_TYPE_LEVEL_HIGH>,
> +                        <0 0 0 4 &intc 0 0 GIC_SPI 267 IRQ_TYPE_LEVEL_HIGH>;
> +        #address-cells = <3>;
> +        #size-cells = <2>;
> +        ranges = <0x01000000 0 0x10010000 0x10010000 0 0x10000>,
> +                 <0x02000000 0 0x10020000 0x10020000 0 0x7fe0000>,
> +                 <0x42000000 0 0x18000000 0x18000000 0 0x8000000>;
> +        bus-range = <0x00 0xff>;

Don't need this unless it's restricted to less than bus 0-255.

> +        clocks = <&rcc CK_BUS_PCIE>;
> +        clock-names = "core";
> +        phys = <&combophy PHY_TYPE_PCIE>;
> +        phy-names = "pcie-phy";
> +        resets = <&rcc PCIE_R>;
> +        reset-names = "core";
> +        msi-parent = <&v2m0>;
> +        wakeup-source;
> +        wake-gpios = <&gpioh 5 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
> +        access-controllers = <&rifsc 76>;
> +        power-domains = <&CLUSTER_PD>;
> +    };
> -- 
> 2.34.1
>