[PATCH v5 3/4] ARM: BCM5301X: add dts files for BCM4708 SoC

[Thomas Petazzoni]

Dear Hauke Mehrtens,

On Mon,  6 Jan 2014 00:46:40 +0100, Hauke Mehrtens wrote:

> +	uart at 18000300 {
> +		compatible = "ns16550";
> +		reg = <0x18000300 0x100>;
> +		interrupts = <GIC_SPI 85 IRQ_TYPE_LEVEL_HIGH>;
> +		clock-frequency = <100000000>;
> +	};
> +
> +	uart at 18000400 {
> +		compatible = "ns16550";
> +		reg = <0x18000400 0x100>;
> +		interrupts = <GIC_SPI 85 IRQ_TYPE_LEVEL_HIGH>;
> +		clock-frequency = <100000000>;
> +	};
> +
> +	scu at 19020000 {
> +		compatible = "arm,cortex-a9-scu";
> +		reg = <0x19020000 0x100>;
> +	};
> +
> +	timer at 19020200 {
> +		compatible = "arm,cortex-a9-global-timer";
> +		reg = <0x19020200 0x100>;
> +		interrupts = <GIC_PPI 11 IRQ_TYPE_LEVEL_HIGH>;
> +		clocks = <&clk_periph>;
> +	};
> +
> +	local-timer at 19020600 {
> +		compatible = "arm,cortex-a9-twd-timer";
> +		reg = <0x19020600 0x100>;
> +		interrupts = <GIC_PPI 13 IRQ_TYPE_LEVEL_HIGH>;
> +		clocks = <&clk_periph>;
> +	};
> +
> +	gic: interrupt-controller at 19021000 {
> +		compatible = "arm,cortex-a9-gic";
> +		#interrupt-cells = <3>;
> +		#address-cells = <0>;
> +		interrupt-controller;
> +		reg = <0x19021000 0x1000>,
> +		      <0x19020100 0x100>;
> +	};
> +
> +	L2: cache-controller at 19022000 {
> +		compatible = "arm,pl310-cache";
> +		reg = <0x19022000 0x1000>;
> +		cache-unified;
> +		cache-level = <2>;
> +	};

I don't know if that has been discussed before, but most of the DTS
group the internal SoC peripherals in some top-level node that
represents the internal bus (or busses) of the SoC, like:

	<some bus name> {
		uart at ... {
			...
		};

		gic at ... {
			...
		};
	};

This allows to have the in-SoC peripherals cleanly separated from other
things in the DTS. It would also you to use a ranges = <...> property
to do an address translation on this bus, and replace the absolute
addresses for each of the peripherals by offsets relative to the base
address of where all peripherals are mapped.

That said, having this top-level node is most likely not a requirement,
so my comment is mainly meant to open the discussion. I'm sure Arnd
will give his opinion on this :)

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com