linux-kernel - Re: [PATCH 4/7] dt-bindings: mfd: Document Macronix MX25F0A controller bindings

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Message-ID: <20190403115146.GR11301@dell>
Date:   Wed, 3 Apr 2019 12:51:46 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Mason Yang <masonccyang@...c.com.tw>
Cc:     broonie@...nel.org, marek.vasut@...il.com,
        linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
        bbrezillon@...nel.org, dwmw2@...radead.org, robh+dt@...nel.org,
        mark.rutland@....com, computersforpeace@...l.com,
        paul.burton@...s.com, stefan@...er.ch, christophe.kerello@...com,
        liang.yang@...ogic.com, geert@...ux-m68k.org,
        devicetree@...r.kernel.org, marcel.ziswiler@...adex.com,
        linux-mtd@...ts.infradead.org, richard@....at,
        miquel.raynal@...tlin.com, juliensu@...c.com.tw,
        zhengxunli@...c.com.tw
Subject: Re: [PATCH 4/7] dt-bindings: mfd: Document Macronix MX25F0A
 controller bindings

On Thu, 28 Mar 2019, Mason Yang wrote:

> Document the bindings used by the Macronix MX25F0A MFD controller.
> 
> Signed-off-by: Mason Yang <masonccyang@...c.com.tw>
> ---
>  .../devicetree/bindings/mfd/mxic-mx25f0a.txt       | 66 ++++++++++++++++++++++
>  1 file changed, 66 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/mxic-mx25f0a.txt
> 
> diff --git a/Documentation/devicetree/bindings/mfd/mxic-mx25f0a.txt b/Documentation/devicetree/bindings/mfd/mxic-mx25f0a.txt
> new file mode 100644
> index 0000000..53b4839
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/mxic-mx25f0a.txt
> @@ -0,0 +1,66 @@
> +Macronix MX25F0A Multi-Function Device Tree Bindings
> +----------------------------------------------------
> +
> +MX25F0A is a MultiFunction Device with SPI and raw NAND, which
> +supports either spi host controller or raw nand controller.
> +
> +Required properties:
> +- compatible: should be "mxic,mx25f0a-mfd"
> +- #address-cells: should be 1
> +- #size-cells: should be 0
> +- reg: should contain 2 entries, one for the registers and one for the direct
> +       mapping area in SPI mode.
> +- reg-names: should contain "regs" and "dirmap"
> +- interrupts: interrupt line connected to this MFD controller
> +
> +Required nodes:
> + - spi :
> +	Node for configuring the SPI controller driver.
> +	Required properties:
> +		- compatible = "mxicy,mx25f0a-spi";
> +		- clock-names: should contain "ps_clk", "send_clk" and
> +			       "send_dly_clk"
> +		- clocks: should contain 3 entries for the "ps_clk", "send_clk"
> +			  and "send_dly_clk" clocks
> +
> +- nand :
> +	Node for configuring the raw nand controller driver.
> +	Required properties:
> +		- compatible = "mxicy,mx25f0a-nand-ctlr";
> +		- nand-ecc-mode = "soft";
> +		- nand-ecc-algo = "bch";
> +
> +Example:
> +
> +	mxic: mx25f0a-mfd@...30000 {

I'm not sure I understand why you are using an MFD for this.

> +		compatible = "mxic,mx25f0a-mfd";
> +		reg = <0x43c30000 0x10000>, <0xa0000000 0x4000000>;
> +		reg-names = "regs", "dirmap";
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		/* either spi or nand */
> +		spi {
> +			compatible = "mxicy,mx25f0a-spi";
> +			clocks = <&clkwizard 0>, <&clkwizard 1>, <&clkc 15>;
> +			clock-names = "send_clk", "send_dly_clk", "ps_clk";
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			flash@0 {
> +				compatible = "jedec,spi-nor";
> +				reg = <0>;
> +				spi-max-frequency = <25000000>;
> +				spi-tx-bus-width = <4>;
> +				spi-rx-bus-width = <4>;
> +			};
> +		};
> +
> +		nand {
> +			compatible = "mxicy,mx25f0a-nand-ctlr";
> +			nand-ecc-mode = "soft";
> +			nand-ecc-algo = "bch";
> +			nand-ecc-step-size = <512>;
> +			nand-ecc-strength = <8>;
> +		};
> +	};

Why not just select one using device tree alone, by:

	spi@...30000 {
		compatible = "mxicy,mx25f0a-spi";
		reg = <0x43c30000 0x10000>, <0xa0000000 0x4000000>;
		reg-names = "regs", "dirmap";
		#address-cells = <1>;
		#size-cells = <0>;
		clocks = <&clkwizard 0>, <&clkwizard 1>, <&clkc 15>;
		clock-names = "send_clk", "send_dly_clk", "ps_clk";
		#address-cells = <1>;
		#size-cells = <0>;

		flash@0 {
			compatible = "jedec,spi-nor";
			reg = <0>;
			spi-max-frequency = <25000000>;
			spi-tx-bus-width = <4>;
			spi-rx-bus-width = <4>;
		};
	};

OR ...

	nand@...30000 {
		compatible = "mxicy,mx25f0a-nand-ctlr";
		reg = <0x43c30000 0x10000>, <0xa0000000 0x4000000>;
		reg-names = "regs", "dirmap";
		#address-cells = <1>;
		#size-cells = <0>;
		nand-ecc-mode = "soft";
		nand-ecc-algo = "bch";
		nand-ecc-step-size = <512>;
		nand-ecc-strength = <8>;
	};

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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