Re: [PATCH 2/2] drivers/amba: probe via device tree

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 05/20/2011 11:00 PM, Segher Boessenkool wrote:
>> The ARM definition of AMBA encompasses a lot of things. It is the
>> definition of the AXI, AHB and APB buses.
>
> So the device tree, which describes the hardware, should call the buses
> axi, ahb or apb as appropriate, and describe the actual physical
> connections.
> The Linux kernel is free to ignore that if it so wishes.
>
>> It also has the definition of the peripheral ID register definitions
>> which primarily only ARM Ltd peripherals implement. You can have those
>> bus types yet not have any peripherals with the ID registers.
>
> The devices are identified in the device tree, you do not need to read
> the ID registers to find them. You should have some way of figuring out
> which devices have the AMBA ID block; maybe add something to the
> "compatible"
> property and have all devices that use this have this register block as the
> first entry in the "reg" property?
>

Identifying actual AMBA devices is already done. The question is how to 
scan the tree for them and how that relates to regular platform devices. 
The AMBA devices have a binding like this:

compatible = "arm,pl011", "arm,amba-device";
arm,amba-deviceid = <0x00341011>;

Rob