linux-kernel - Re: [PATCH 1/2] dt-bindings: phy: Document cadence Sierra PHY bindings

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Date:   Mon, 15 Oct 2018 14:09:29 -0500
From:   Rob Herring <robh@...nel.org>
To:     Alan Douglas <adouglas@...ence.com>
Cc:     kishon@...com, linux-kernel@...r.kernel.org, mark.rutland@....com,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: phy: Document cadence Sierra PHY
 bindings

On Wed, Oct 03, 2018 at 05:02:25PM +0100, Alan Douglas wrote:
> Add DT binding documentation for Sierra PHY.  The PHY supports
> a number of different protocols, including PCIe and USB.
> 
> The PHY lanes may be configured as single or multi-lane links.
> Each link is treated as a separate sub-node.  For example, if
> there are 4 lanes in total the first 2 might be configured as
> a multi-lane PCIe link while the other two are single lane
> USB links, and in this case there would be 3 sub-nodes.
> 
> There are two resets for the PHY block (one for APB register
> access, one for the PHY link) and separate resets for each
> link.  For multi-lane links, the reset corresponds to the
> reset line on the master lane, the resets on other lanes
> have no effect.
> 
> Signed-off-by: Alan Douglas <adouglas@...ence.com>
> ---
>  .../devicetree/bindings/phy/cdns-sierra-phy.txt    | 68 ++++++++++++++++++++++
>  1 file changed, 68 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/phy/cdns-sierra-phy.txt
> 
> diff --git a/Documentation/devicetree/bindings/phy/cdns-sierra-phy.txt b/Documentation/devicetree/bindings/phy/cdns-sierra-phy.txt
> new file mode 100644
> index 0000000..0e2f3e3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/phy/cdns-sierra-phy.txt
> @@ -0,0 +1,68 @@
> +Cadence Sierra PHY
> +-----------------------
> +
> +Required properties:
> +- compatible:	cdns,sierra-phy-t0
> +- clocks:	Must contain an entry in clock-names.
> +		See ../clocks/clock-bindings.txt for details.
> +- clock-names:	Must be "phy_clk"
> +- resets:	Must contain an entry for each in reset-names.
> +		See ../reset/reset.txt for details.
> +- reset-names:	Must include "sierra_reset" and "sierra_apb" and one for each
> +		sub-node.
> +		"sierra_reset" must control the reset line to the PHY.
> +		"sierra_apb" must control the reset line to the APB PHY
> +		interface.
> +		The name of the reset for each sub-node should match the full
> +		name of the sub-node.  The sub-node resets must control the
> +		reset line for the master lane of the sub-node.

Add a resets property to the sub-nodes instead.

> +- reg:		register range for the PHY.
> +- #address-cells: Must be 1
> +- #size-cells:	Must be 0
> +
> +Optional properties:
> +- cdns,autoconf:	A boolean property whose presence indicates that the
> +			PHY registers will be configured by hardware. If not
> +			present, all sub-node optional properties must be
> +			provided.
> +
> +Sub-nodes:
> +  Each group of PHY lanes with a single master lane should be represented as
> +  a sub-node. Note that the actual configuration of each lane is determined by
> +  hardware strapping, and must match the configuration specified here.
> +
> +Sub-node required properties:
> +- #phy-cells:	Generic PHY binding; must be 0.
> +
> +Sub-node optional properties:
> +- reg:			The master lane number.  This is the lowest numbered
> +			lane in the lane group.

How do you name the nodes if this is optional?

> +- cdns,num-lanes:	Number of lanes in this group.  From 1 to 4.  The
> +			group is made up of consecutive lanes.
> +- cdns,phy-type:	Can be PHY_TYPE_PCIE or PHY_TYPE_USB3, depending on
> +			configuration of lanes.
> +
> +Example:
> +	pcie_phy4: pcie-phy@...40000 {
> +		compatible = "cdns,sierra-phy-t0";
> +		reg = <0x0 0xfd240000 0x0 0x40000>;
> +		resets = <&phyrst 0>, <&phyrst 1>, <&phyrst 2>, <&phyrst 4>;
> +		reset-names = "sierra_reset", "sierra_apb",
> +				"pcie_phy@0", "pcie_phy@2";
> +		clocks = <&phyclock>;
> +		clock-names = "phy_clk";
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		pcie0_phy0: pcie-phy@0 {
> +				reg = <0>;
> +				cdns,num-lanes = <2>;
> +				#phy-cells = <0>;
> +				cdns,phy-type = <PHY_TYPE_PCIE>;
> +		};
> +		pcie0_phy1: pcie-phy@2 {
> +				reg = <2>;
> +				cdns,num-lanes = <1>;
> +				#phy-cells = <0>;
> +				cdns,phy-type = <PHY_TYPE_PCIE>;
> +		};
> +
> -- 
> 1.9.0
>