Re: [PATCH V2 4/4] ARM64 LPC: support earlycon for UART connected to LPC

From: Arnd Bergmann
Date: Wed Sep 14 2016 - 08:37:28 EST

On Wednesday, September 14, 2016 7:26:22 PM CEST zhichang wrote:
> >
> >> Hip06 LPC uart need two base addresses for earlycon.
> >> 2. the IO type is mmio to introduce a memory base address to access LPC register file. But the real uart
> >> IO type is UPIO_PORT. This is spcial...
> >
> > This sounds like a deficiency in the of_setup_earlycon() function,
> > which can only handle MMIO addresses, and won't actually
> > be able to understand nodes without a "ranges" property like
> > you have here.
> >
> Yes.
> The current of_setup_earlycon only support MMIO and the first reg property must be memory.
> We can not support our LPC uart without any new code.
> But we can implement a private earlycon setup function and register
> it to the __earlycon_table, things will be ok.

I still think you should adapt of_setup_earlycon instead to handle IORESOURCE_IO