Subject: Re: [RFC] Device tree for new desktop platform in arch/powerpc

From: Segher Boessenkool <[email-masked]>
Date: Tue, 19 Jun 2007 08:16:09 +0200

>>   	interrupt-controller {
>> 		device_type = "interrupt-controller";
>> 		compatible = "chrp,iic";
>
> Is there a device binding defined somewhere for "chrp,iic"?

In the CHRP platform binding, which doesn't apply here.

>> 		keyboard {
>> 			device_type = "keyboard";
>> 			compatible = "pnpPNP,303";
>> 			reg = <0>;
>> 		};
>
>> 		mouse {
>> 			device_type = "mouse";
>> 			compatible = "pnpPNP,f03";
>> 			reg = <1>;
>> 		};
>> 	};
>
>> 	timer@40 {
>> 		device_type = "timer";
>
> For flat device trees we're generally avoiding setting the device_type
> property unless there is a clearly defined "class binding" which
> applies.  There are a number of cases here where I'm not sure if
> that's true.

Keyboard and mouse have defined "device_type"s.  Timer I
don't think so.

Either way, I'd leave out the device_type here, the OS
isn't supposed to use it anyway.

>> 	serial@3f8 {
>> 		device_type = "serial";
>> /*		compatible = "pnpPNP,501";*/
>> 		compatible = "ns16550";
>> 		reg = <3f8 8>;
>> 		interrupts = <4 3>;			// IRQ4 (rising edge)
>> 		interrupt-parent = <&interrupt-controller>;
>> 		clock-frequency = <0>;			// Not necessary?
>
> Probably necessary, but may need to be filled in from the bootwrapper.

If absent, "clock-frequency" should be taken to be the
default thing.  Actually, for pnpPNP (PC-style) serial,
the clock frequency is fixed.

>>   	pci@80000000 {
>> 		device_type = "pci";
>> 		bus-frequency = <01fca055>;		// 33.3MHz

So write it in decimal...

Segher