Re: [PATCH v2 4/6] dt-bindings: PCI: Add SiFive FU740 PCIe host controller

From: Rob Herring <robh@kernel.org>
To: Greentime Hu <greentime.hu@sifive.com>
Cc: paul.walmsley@sifive.com, hes@sifive.com, erik.danie@sifive.com,
	zong.li@sifive.com, bhelgaas@google.com, palmer@dabbelt.com,
	aou@eecs.berkeley.edu, mturquette@baylibre.com, sboyd@kernel.org,
	lorenzo.pieralisi@arm.com, p.zabel@pengutronix.de,
	alex.dewar90@gmail.com, khilman@baylibre.com,
	hayashi.kunihiko@socionext.com, vidyas@nvidia.com,
	jh80.chung@samsung.com, linux-pci@vger.kernel.org,
	devicetree@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
	helgaas@kernel.org
Subject: Re: [PATCH v2 4/6] dt-bindings: PCI: Add SiFive FU740 PCIe host controller
Date: Tue, 23 Mar 2021 14:35:08 -0600	[thread overview]
Message-ID: <20210323203508.GA1251968@robh.at.kernel.org> (raw)
In-Reply-To: <8008af6d86737b74020d7d8f9c3fbc9b500e9993.1615954046.git.greentime.hu@sifive.com>

On Thu, Mar 18, 2021 at 02:08:11PM +0800, Greentime Hu wrote:
> Add PCIe host controller DT bindings of SiFive FU740.
> 
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> ---
>  .../bindings/pci/sifive,fu740-pcie.yaml       | 119 ++++++++++++++++++
>  1 file changed, 119 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pci/sifive,fu740-pcie.yaml
> 
> diff --git a/Documentation/devicetree/bindings/pci/sifive,fu740-pcie.yaml b/Documentation/devicetree/bindings/pci/sifive,fu740-pcie.yaml
> new file mode 100644
> index 000000000000..c25a91b18cd7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pci/sifive,fu740-pcie.yaml
> @@ -0,0 +1,119 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pci/sifive,fu740-pcie.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: SiFive fu740 PCIe host controller
> +
> +description:
> +  SiFive fu740 PCIe host controller is based on the Synopsys DesignWare
> +  PCI core. It shares common features with the PCIe DesignWare core and
> +  inherits common properties defined in
> +  Documentation/devicetree/bindings/pci/designware-pcie.txt.
> +
> +maintainers:
> +  - Paul Walmsley <paul.walmsley@sifive.com>
> +  - Greentime Hu <greentime.hu@sifive.com>
> +
> +allOf:
> +  - $ref: /schemas/pci/pci-bus.yaml#
> +
> +properties:
> +  compatible:
> +    const: sifive,fu740-pcie
> +
> +  reg:
> +    maxItems: 4

What's the 4th item because there's only 3 names:

> +
> +  reg-names:
> +    items:
> +      - const: dbi
> +      - const: config
> +      - const: mgmt
> +
> +  device_type:
> +    const: pci

Already in pci-bus.yaml

> +
> +  dma-coherent:
> +    description: Indicates that the PCIe IP block can ensure the coherency
> +
> +  bus-range:
> +    description: Range of bus numbers associated with this controller.

Already in pci-bus.yaml

> +
> +  num-lanes: true

Need to define possible values if not all of 1,2,4,8,16.

> +
> +  msi-parent: true
> +
> +  interrupt-names:
> +    items:
> +      - const: msi
> +      - const: inta
> +      - const: intb
> +      - const: intc
> +      - const: intd
> +
> +  resets:
> +    description: A phandle to the PCIe power up reset line
> +
> +  pwren-gpios:
> +    description: Should specify the GPIO for controlling the PCI bus device power on

maxItems: 1

> +
> +  perstn-gpios:
> +    description: Should specify the GPIO for controlling the PCI bus device reset

The DWC binding and pci.txt already define 'reset-gpios' for this 
purpose.

> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - device_type

pci-bus.yaml already requires this.

> +  - dma-coherent
> +  - bus-range

This generally doesn't need to be required unless the h/w can't support 
0-0xff.

> +  - ranges

pci-bus.yaml already requires this.

> +  - num-lanes
> +  - interrupts
> +  - interrupt-names
> +  - interrupt-parent
> +  - interrupt-map-mask
> +  - interrupt-map
> +  - clock-names
> +  - clocks
> +  - resets
> +  - pwren-gpios
> +  - perstn-gpios
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    pcie@e00000000 {
> +        #address-cells = <3>;
> +        #interrupt-cells = <1>;
> +        #size-cells = <2>;
> +        compatible = "sifive,fu740-pcie";
> +        reg = <0xe 0x00000000 0x1 0x0

Humm, 4GB for DBI space? The DWC controller doesn't have that much 
space, and the kernel will map *all* of that. That's not an 
insignificant amount of memory just for page tables.

> +               0xd 0xf0000000 0x0 0x10000000
> +               0x0 0x100d0000 0x0 0x1000>;

<> around each reg entry.

> +        reg-names = "dbi", "config", "mgmt";
> +        device_type = "pci";
> +        dma-coherent;
> +        bus-range = <0x0 0xff>;
> +        ranges = <0x81000000  0x0 0x60080000  0x0 0x60080000 0x0 0x10000        /* I/O */
> +                  0x82000000  0x0 0x60090000  0x0 0x60090000 0x0 0xff70000      /* mem */
> +                  0x82000000  0x0 0x70000000  0x0 0x70000000 0x0 0x1000000      /* mem */
> +                  0xc3000000 0x20 0x00000000 0x20 0x00000000 0x20 0x00000000>;  /* mem prefetchable */

<> around each ranges entry.

> +        num-lanes = <0x8>;
> +        interrupts = <56 57 58 59 60 61 62 63 64>;

And here.

> +        interrupt-names = "msi", "inta", "intb", "intc", "intd";
> +        interrupt-parent = <&plic0>;
> +        interrupt-map-mask = <0x0 0x0 0x0 0x7>;
> +        interrupt-map = <0x0 0x0 0x0 0x1 &plic0 57>,
> +                        <0x0 0x0 0x0 0x2 &plic0 58>,
> +                        <0x0 0x0 0x0 0x3 &plic0 59>,
> +                        <0x0 0x0 0x0 0x4 &plic0 60>;
> +        clock-names = "pcie_aux";
> +        clocks = <&prci PRCI_CLK_PCIE_AUX>;
> +        resets = <&prci 4>;
> +        pwren-gpios = <&gpio 5 0>;
> +        perstn-gpios = <&gpio 8 0>;
> +    };
> -- 
> 2.30.2
> 

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