linux-kernel - Re: [PATCH 1/3] clk: meson: add DT documentation for emmc clock controller

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Date:   Tue, 03 Jul 2018 10:16:16 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Yixun Lan <yixun.lan@...ogic.com>,
        Neil Armstrong <narmstrong@...libre.com>
Cc:     Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Liang Yang <liang.yang@...ogic.com>,
        Qiufang Dai <qiufang.dai@...ogic.com>,
        Jian Hu <jian.hu@...ogic.com>, linux-clk@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 1/3] clk: meson: add DT documentation for emmc clock
 controller

On Tue, 2018-07-03 at 14:57 +0000, Yixun Lan wrote:
> Document the EMMC sub clock controller driver, the potential consumer
> of this driver is EMMC or NAND.
> 
> Signed-off-by: Yixun Lan <yixun.lan@...ogic.com>
> ---
>  .../bindings/clock/amlogic,emmc-clkc.txt      | 45 +++++++++++++++++++
>  1 file changed, 45 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/amlogic,emmc-clkc.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/amlogic,emmc-clkc.txt b/Documentation/devicetree/bindings/clock/amlogic,emmc-clkc.txt
> new file mode 100644
> index 000000000000..5534bd446363
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/amlogic,emmc-clkc.txt
> @@ -0,0 +1,45 @@
> +* Amlogic EMMC Sub Clock Controller Driver
> +
> +The Amlogic EMMC clock controller generates and supplies clock to support
> +EMMC and NAND controller
> +
> +Required Properties:
> +
> +- compatible: should be:
> +		"amlogic,emmc-clkc"

missing clocks and clock-names here

> +
> +- #clock-cells: should be 1.
> +
> +Two clocks are provided as the parent of this EMMC clock controller driver from
> +upper layer clock controller - eg "amlogic,axg-clkc" in AXG platfrom.
> +The main consumer of this driver is EMMC or NAND, to specify which the clock
> +they may consume, the preprocessor macros in the dt-bindings/clock/emmc-clkc.h
> +header and can be used in device tree sources.

Not sure this explanation belongs in dt-binding documentation.
Maybe this should be in the driver itself.

> +
> +Parent node should have the following properties :
> +- compatible: "syscon", "simple-mfd, and "amlogic,emmc-clkc"
> +- reg: base address and size of the EMMC control register space.
> +
> +Example: Clock controller node:
> +
> +sd_emmc_c_clkc: clock-controller@...0 {
> +	compatible = "amlogic,emmc-clkc", "syscon", "simple-mfd";
> +	reg = <0x0 0x7000 0x0 0x4>;
> +	#clock-cells = <1>;
> +
> +	clock-names = "clkin0", "clkin1";
> +	clocks = <&clkc CLKID_SD_EMMC_C_CLK0>,
> +			<&clkc CLKID_FCLK_DIV2>;
> +};
> +

Not sure the following is necessary, you don't really to show how to use a clock
controller.

> +Example: NAND controller node that consumes the clock generated by the clock
> +  controller:
> +
> +	nand: nfc@...0 {
> +		compatible = "amlogic,meson-axg-nfc";
> +		reg = <0x0 0x7800 0x0 0x100>;
> +		interrupts = <GIC_SPI 34 IRQ_TYPE_EDGE_RISING>;
> +		clocks = <&clkc CLKID_SD_EMMC_C>,
> +				<&sd_emmc_c_clkc CLKID_EMMC_C_DIV>;
> +		clock-names = "core", "device";
> +	};