linux-kernel - Re: [PATCH 3/3] arm64: dts: ti: k3-j7200-mcu-wakeup: Split fss node up

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Date:   Mon, 24 Apr 2023 13:55:47 -0500
From:   Andrew Davis <afd@...com>
To:     Nishanth Menon <nm@...com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>
CC:     <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Tero Kristo <kristo@...nel.org>, <vaishnav.a@...com>,
        <u-kumar1@...com>
Subject: Re: [PATCH 3/3] arm64: dts: ti: k3-j7200-mcu-wakeup: Split fss node
 up

On 4/24/23 12:36 PM, Nishanth Menon wrote:
> fss node claims to be entirely a syscon node, but it is really two
> parts of it - one a syscon that controls the hbmc mux and a simple bus
> where ospi, hbmc peripherals are located. So model it accordingly by
> splitting the node up and using ti,j721e-system-controller to describe
> the syscon
> 
> Signed-off-by: Nishanth Menon <nm@...com>
> ---
>   .../boot/dts/ti/k3-j7200-mcu-wakeup.dtsi      | 21 +++++++++++++------
>   1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi b/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> index b58a31371bf3..7653cb191be1 100644
> --- a/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
> @@ -338,18 +338,27 @@ mcu_spi2: spi@...20000 {
>   		status = "disabled";
>   	};
>   
> -	fss: syscon@...00000 {
> -		compatible = "syscon", "simple-mfd";
> +	hbmc_syscon: syscon@...00000 {
> +		compatible = "ti,j721e-system-controller", "syscon", "simple-mfd";
>   		reg = <0x00 0x47000000 0x00 0x100>;
> -		#address-cells = <2>;
> -		#size-cells = <2>;
> -		ranges;
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges = <0x00 0x00 0x47000000 0x100>;
>   
> -		hbmc_mux: hbmc-mux {
> +		hbmc_mux: mux-controller@4 {
>   			compatible = "mmio-mux";
> +			reg = <0x4 0x2>;
>   			#mux-control-cells = <1>;
>   			mux-reg-masks = <0x4 0x2>; /* HBMC select */
>   		};
> +	};
> +
> +	fss: bus@...30000 {
> +		compatible = "simple-bus";
> +		reg = <0x0 0x47030000 0x0 0x100>;
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
>   
>   		hbmc: hyperbus@...34000 {
>   			compatible = "ti,am654-hbmc";


I hope all the things you had to do here show you what I mean in my
comments on [0] :)

I've posted a first step patch that allows "reg-mux" node to work with
regular reg properties[1]. Which means this patch could have been just this:

--- a/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j7200-mcu-wakeup.dtsi
@@ -305,15 +305,16 @@ wkup_i2c0: i2c@...20000 {
                 status = "disabled";
         };
  
-       fss: syscon@...00000 {
-               compatible = "syscon", "simple-mfd";
+       fss: bus@...00000 {
+               compatible = "simple-bus";
                 reg = <0x00 0x47000000 0x00 0x100>;
                 #address-cells = <2>;
                 #size-cells = <2>;
                 ranges;
  
                 hbmc_mux: hbmc-mux {
-                       compatible = "mmio-mux";
+                       compatible = "reg-mux";
+                       reg = <0x00 0x47000004 0x00 0x2>;
                         #mux-control-cells = <1>;
                         mux-reg-masks = <0x4 0x2>; /* HBMC select */
                 };

Andrew

[0] https://lore.kernel.org/all/76da0b98-3274-b047-db11-ecabc117ae11@ti.com/
[1] https://lore.kernel.org/all/20230424184810.29453-1-afd@ti.com/