Re: [PATCH 1/3] dt-bindings: pci: Add devicetree binding for Qualcomm PCIe EP controller

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Jun 02, 2021 at 09:22:29AM -0500, Rob Herring wrote:
> On Wed, Jun 2, 2021 at 7:08 AM Manivannan Sadhasivam
> <manivannan.sadhasivam@linaro.org> wrote:
> >
> > Add devicetree binding for Qualcomm PCIe EP controller used in platforms
> > like SDX55. The EP controller is based on the Designware core with
> > Qualcomm specific wrappers.
> 
> Is the block EP only or configurable EP or host?
> 

Configurable core. We already support the RC mode in a separate driver and
binding. I initially thought about merging both in a single driver &
binding but that seemed unnecessarily complex, so settled with this.

> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> >  .../devicetree/bindings/pci/qcom,pcie-ep.yaml | 139 ++++++++++++++++++
> >  1 file changed, 139 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/pci/qcom,pcie-ep.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/pci/qcom,pcie-ep.yaml b/Documentation/devicetree/bindings/pci/qcom,pcie-ep.yaml
> > new file mode 100644
> > index 000000000000..0f9140e93bcb
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pci/qcom,pcie-ep.yaml
> > @@ -0,0 +1,139 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/pci/qcom,pcie-ep.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Qualcomm PCIe Endpoint Controller binding
> > +
> > +maintainers:
> > +  - Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > +
> > +allOf:
> > +  - $ref: "pci-ep.yaml#"
> > +
> > +properties:
> > +  compatible:
> > +    const: qcom,pcie-ep
> 
> SoC specific please.
>

Okay

> > +
> > +  reg:
> > +    items:
> > +      - description: Designware PCIe registers
> > +      - description: External local bus interface registers
> > +      - description: Address Translation Unit (ATU) registers
> > +      - description: Memory region used to map remote RC address space
> > +      - description: Qualcomm specific PARF configuration registers
> > +      - description: Qualcomm specific TCSR registers
> > +
> > +  reg-names:
> > +    items:
> > +      - const: dbi
> > +      - const: elbi
> > +      - const: atu
> > +      - const: addr_space
> > +      - const: parf
> > +      - const: tcsr
> 
> This should be in the same order as the host side. Unfortunately,
> that's not consistent, but to pick one:
> 
> reg-names = "parf", "dbi", "elbi", "atu", "config";
> 

Okay, I'll align with the RC binding.

> 
> > +
> > +  clocks:
> > +    items:
> > +      - description: PCIe CFG AHB clock
> > +      - description: PCIe Auxiliary clock
> > +      - description: PCIe Master AXI clock
> > +      - description: PCIe Slave AXI clock
> > +      - description: PCIe Reference clock
> > +      - description: PCIe Sleep clock
> > +      - description: PCIe Slave Q2A AXI clock
> > +
> > +  clock-names:
> > +    items:
> > +      - const: cfg
> > +      - const: aux
> > +      - const: bus_master
> > +      - const: bus_slave
> > +      - const: ref
> > +      - const: sleep
> > +      - const: slave_q2a
> 
> Again, try to keep the same ordering.
> 
> I have to wonder where 'pipe' clock is that most of the QCom
> implementations have?
> 

Pipe clock is managed by the PHY driver. So the PCIe drivers need not to
worry about it.

> > +
> > +  interrupts:
> > +    maxItems: 1
> > +    description: PCIe Global interrupt
> > +
> > +  interrupt-names:
> > +    const: int_global
> 
> 'int_' is redundant, drop.
> 

Okay

> > +
> > +  perst-gpios:
> > +    description: PCIe endpoint reset GPIO
> 
> An input, right?
> 

Yes, will mention.

> > +    maxItems: 1
> > +
> > +  wake-gpios:
> > +    description: PCIe endpoint wake GPIO
> > +    maxItems: 1
> > +
> > +  resets:
> > +    maxItems: 1
> > +
> > +  reset-names:
> > +    const: core_reset
> 
> Not yet another name. We already have 'pci' and 'core' in the cases of
> a single reset.
> 

Okay

> > +
> > +  power-domains:
> > +    maxItems: 1
> > +
> > +  phys:
> > +    maxItems: 1
> > +
> > +  phy-names:
> > +    const: pciephy
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - reg-names
> > +  - clocks
> > +  - clock-names
> > +  - interrupts
> > +  - interrupt-names
> > +  - perst-gpios
> > +  - resets
> > +  - reset-names
> > +  - power-domains
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/qcom,gcc-sdx55.h>
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > +    pcie_ep: pcie-ep@40000000 {
> > +        compatible = "qcom,pcie-ep";
> > +
> > +        reg = <0x40000000 0xf1d>,
> > +              <0x40000f20 0xc8>,
> > +              <0x40001000 0x1000>,
> > +              <0x42000000 0x1000>,
> > +              <0x01c00000 0x3000>,
> > +              <0x01fcb000 0x1000>;
> > +        reg-names = "dbi", "elbi", "atu", "addr_space", "parf", "tcsr";
> > +
> > +        clocks = <&gcc GCC_PCIE_CFG_AHB_CLK>,
> > +             <&gcc GCC_PCIE_AUX_CLK>,
> > +             <&gcc GCC_PCIE_MSTR_AXI_CLK>,
> > +             <&gcc GCC_PCIE_SLV_AXI_CLK>,
> > +             <&gcc GCC_PCIE_0_CLKREF_CLK>,
> > +             <&gcc GCC_PCIE_SLEEP_CLK>,
> > +             <&gcc GCC_PCIE_SLV_Q2A_AXI_CLK>;
> > +        clock-names = "cfg", "aux", "bus_master", "bus_slave",
> > +                      "ref", "sleep", "slave_q2a";
> > +
> > +        interrupts = <GIC_SPI 140 IRQ_TYPE_LEVEL_HIGH>;
> > +        interrupt-names = "int_global";
> > +        perst-gpios = <&tlmm 57 GPIO_ACTIVE_HIGH>;
> > +        wake-gpios = <&tlmm 53 GPIO_ACTIVE_LOW>;
> > +        resets = <&gcc GCC_PCIE_BCR>;
> > +        reset-names = "core_reset";
> > +        power-domains = <&gcc PCIE_GDSC>;
> > +        phys = <&pcie0_lane>;
> > +        phy-names = "pciephy";
> > +        max-link-speed = <3>;
> > +        num-lanes = <2>;
> 
> Should be documented. I'd assume the max is less than 16 which is
> presumably what pcie-ep.yaml allows.
> 

okay

Thanks,
Mani

> > +    };
> > --
> > 2.25.1
> >