Re: [PATCH v5 5/5] usb: dwc3: rockchip: add devicetree bindings documentation

[Heiko Stuebner <heiko@sntech.de>]

Hi William,

Am Donnerstag, 30. Juni 2016, 19:16:40 schrieb William Wu:
> This patch adds the devicetree documentation required for Rockchip
> USB3.0 core wrapper consisting of USB3.0 IP from Synopsys.
> 
> It supports DRD mode, and could operate in device mode (SS, HS, FS)
> and host mode (SS, HS, FS, LS).
> 
> Signed-off-by: William Wu <william.wu@rock-chips.com>
> ---
> Changes in v5:
> - rename clock-names, and remove unnecessary clocks (Heiko)
> 
> Changes in v4:
> - modify commit log, and add phy documentation location (Sergei)
> 
> Changes in v3:
> - add dwc3 address (balbi)
> 
> Changes in v2:
> - add rockchip,dwc3.txt to Documentation/devicetree/bindings/ (balbi,
> Brian)
> 
>  .../devicetree/bindings/usb/rockchip,dwc3.txt      | 40
> ++++++++++++++++++++++ 1 file changed, 40 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/usb/rockchip,dwc3.txt
> 
> diff --git a/Documentation/devicetree/bindings/usb/rockchip,dwc3.txt
> b/Documentation/devicetree/bindings/usb/rockchip,dwc3.txt new file mode
> 100644
> index 0000000..9c85e19
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/usb/rockchip,dwc3.txt
> @@ -0,0 +1,40 @@
> +Rockchip SuperSpeed DWC3 USB SoC controller
> +
> +Required properties:
> +- compatible:	should contain "rockchip,rk3399-dwc3" for rk3399 SoC
> +- clocks:	A list of phandle + clock-specifier pairs for the
> +		clocks listed in clock-names
> +- clock-names:	Should contain the following:
> +  "ref_clk"	Controller reference clk, have to be 24 MHz
> +  "suspend_clk"	Controller suspend clk, have to be 24 MHz or 32 KHz
> +  "bus_clk_otg0"Master/Core clock, have to be >= 62.5 MHz for SS
> +		operation and >= 60MHz for HS operation

why is it called "bus_clk_otg0" not just simply "bus_clk". As far as I
understand it (and see it in the TRM), you have two dwc3 controllers
(otg0 and otg1) and clock-names are always meant from the perspective of
the individual ip-block. So a devicetree would have:

	usbdrd3_0: usb@fe800000 {
		compatible = "rockchip,rk3399-dwc3";
		clocks = <&cru SCLK_USB3OTG0_REF>, <&cru SCLK_USB3OTG0_SUSPEND>,
			 <&cru ACLK_USB3OTG0>, <&cru ACLK_USB3_GRF>;
		clock-names = "ref_clk", "suspend_clk",
			      "bus_clk", "grf_clk";
		...
	};

	usbdrd3_1: usb@fe900000 {
		compatible = "rockchip,rk3399-dwc3";
		clocks = <&cru SCLK_USB3OTG1_REF>, <&cru SCLK_USB3OTG1_SUSPEND>,
			 <&cru ACLK_USB3OTG1>, <&cru ACLK_USB3_GRF>;
		clock-names = "ref_clk", "suspend_clk",
			      "bus_clk", "grf_clk";
		...
	};


The rest looks really nice now.


Heiko

> +  "grf_clk"	Controller grf clk
> +
> +Required child node:
> +A child node must exist to represent the core DWC3 IP block. The name of
> +the node is not important. The content of the node is defined in
> dwc3.txt. +
> +Phy documentation is provided in the following places:
> +Documentation/devicetree/bindings/phy/rockchip,dwc3-usb-phy.txt
> +
> +Example device nodes:
> +
> +	usbdrd3_0: usb@fe800000 {
> +		compatible = "rockchip,rk3399-dwc3";
> +		clocks = <&cru SCLK_USB3OTG0_REF>, <&cru SCLK_USB3OTG0_SUSPEND>,
> +			 <&cru ACLK_USB3OTG0>, <&cru ACLK_USB3_GRF>;
> +		clock-names = "ref_clk", "suspend_clk",
> +			      "bus_clk_otg0", "grf_clk";
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +		status = "disabled";
> +		usbdrd_dwc3_0: dwc3@fe800000 {
> +			compatible = "snps,dwc3";
> +			reg = <0x0 0xfe800000 0x0 0x100000>;
> +			interrupts = <GIC_SPI 105 IRQ_TYPE_LEVEL_HIGH>;
> +			dr_mode = "otg";
> +			status = "disabled";
> +		};
> +	};
> --
> 1.9.1