Re: FDT syscon driver

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Jared McNeill <jmcneill%invisible.ca@localhost> wrote:
>On Sun, 1 Jul 2018, Robert Swindells wrote:
>>
>> Jared McNeill <jmcneill%invisible.ca@localhost> wrote:
>>> How to access it is dictated by the binding spec for your device. You need
>>> some way to find the phandle. Two methods I have encountered:
>>
>> [snip]
>>
>> The Odroid C2 doesn't use either of them, there are no cross references
>> and the devices are at the same level in the tree.
>
>Can you point me to an example?

The ethernet controller has two registers within the page at 0xc8834000

		periphs@c8834000 {
			compatible = "simple-bus";
			reg = <0x00000000 0xc8834000 0x00000000 0x00002000>;
			#address-cells = <0x00000002>;
			#size-cells = <0x00000002>;
			ranges = <0x00000000 0x00000000 0x00000000 0xc8834000 0x00000000 0x00002000>;


		ethernet@c9410000 {
			compatible = "amlogic,meson-gx-dwmac", "amlogic,meson-gx
bb-dwmac", "snps,dwmac";
			reg = <0x00000000 0xc9410000 0x00000000 0x00010000 0x00000000 0xc8834540 0x00000000 0x00000004>;
			interrupts = <0x00000000 0x00000008 0x00000001>;
			interrupt-names = "macirq";
			status = "okay";
			clocks = <0x0000000c 0x00000024 0x0000000c 0x00000004 0x0000000c 0x0000000f>;   
			clock-names = "stmmaceth", "clkin0", "clkin1";
			pinctrl-0 = <0x00000018>;
			pinctrl-names = "default";
			phy-handle = <0x00000019>;
			phy-mode = "rgmii";
			snps,reset-gpio = <0x0000001a 0x0000000e 0x00000000>;
			snps,reset-delays-us = <0x00000000 0x00002710 0x000f4240>;
			snps,reset-active-low;
			amlogic,tx-delay-ns = <0x00000002>;

There are other things within the same page:

			rng {
				compatible = "amlogic,meson-rng";
				reg = <0x00000000 0x00000000 0x00000000 0x00000004>;
				clocks = <0x0000000c 0x00000019>;
				clock-names = "core";
			};
			pinctrl@4b0 {
				compatible = "amlogic,meson-gxbb-periphs-pinctrl";
                                ...

The device tree from Hardkernel's kernel is different again to the
mainline one:

	gpiomem {
		compatible = "amlogic,meson-gpiomem";
		reg = <0x0 0xc8834000 0x0 0x1000>;
		status = "okay";
	};

	ethmac: ethernet@0xc9410000{
		compatible = "amlogic, gxbb-rgmii-dwmac";
		reg = <0x0 0xc9410000 0x0 0x10000
		0x0 0xc8834540 0x0 0x8>; 
		interrupts = <0 8 1>;
		phy-mode= "rgmii";
		pinctrl-names = "eth_pins";
		pinctrl-0 = <&eth_pins>;
		rst_pin-gpios = <&gpio GPIOZ_14 0>;
		mc_val = <0x1621>;
		resets = <&clock GCLK_IDX_ETHERNET>;
		reset-names = "ethpower";
		interrupt-names = "macirq";
		clocks = <&clock CLK_81>;
		clock-names = "ethclk81";
		 max-frame-size = <3582>;