[U-Boot] [PATCH 01/10] mx27: basic cpu support

[Magnus Lilja]

Dear Wolfgang,

2009/5/14 Wolfgang Denk <wd at denx.de>:
>> I see. PowerPC in Linux uses C structs too. But there are still a lot of
>> code that uses registers offsets in Linux, so my arguments are the same:
>> requirement to convert offsets to C struct brings additional
>> difficulties to porting (and maintaining already ported) drivers from Linux.
>
> I understand your argument, but the decision has been made. We want to
> get rid of this pointer stuff in U-Boot, and do not accept any new
> code like this any more.

After having browsed some powerpc code I can find two different ways
the struct-thing is used:
Variant A, all members declared volatile:
struct controller_reg {
  volatile uint32_t reg1;
  volatile uint32_t reg2;
}

struct controller_reg *controller = 0xCAFE0000;

Or variant B:
struct controller_reg {
  uint32_t reg1;
  uint32_t reg2;
}

volatile struct controller_reg *controller = 0xCAFE0000;

Also, is it OK to access the registers using reg = controller->reg1 or
should we use reg = readl(&controller->reg1)?

I ask this since I don't want to iterate the patches on the mailing
list too many times...

Regards, Magnus