[U-Boot] [PATCH] ftsmc020: enhance for features and asm support.

[Wolfgang Denk <wd@denx.de>]

Dear Macpaul Lin,

In message <AANLkTi=umWPj8zK+AvL6H8EarhbqSxN2G=8itXXZG6cS@mail.gmail.com> you wrote:
> 
> There are lots of register offset is widely been used both in
> lowlevel_init and C environment.

Yes, there is a lot os mess that piled up over the years.  It will
take time to clean this up.

> If there is a code wrote as writel(0x1,  AT91_ASM_SMC_SETUP0);
> originally must be rewrote as
> writel(0x1,  AT91_SMC_BASE + AT91_ASM_SMC_SETUP0);

No, this should be rewritten to acces a C struct instead.
These offesets must ONLY be used in assembler files, but NOT in any C
code.

> I meant, should we make a script that could auto generate asm-offset
> like a translation from
> struct ftsmc020 {
>     unsigned bank0_cr;
>     unsigned bank0_tpr;
>     ...
> }
> into
> #define FTSMC020_BANK0_CR 0x00;
> or
> #define FTSMC020_BANK0_TPR (4);

No.  It makes no sense to provide offset fefinitions for allexisting
struct entries.  Onle those are needed that are actually being used in
assembler code, and this should be only a handful.

If you find yourself using more of them, you should stop and ask
yourself why you are not writing this code in C.

> without manually reworte the structure in the way as
> OFFSET(FTSMC020_BANK0_CR, ftsmc020, bank0_cr);
> and create a new specific header file for make-asm-offset?

I repeat again: I consider this manual unrolling of the nested structs
a Bad Thing.  You should have separate offsets for each of the nested
structs.

> You are right, the comments of FTSMC020_BANK0_TPR (4) is really bad
> for human reading.

Actually not. They explain exactly what's going on there.

> However, when people implementing lowlevel_init or other assembly
> files, they still need such kind of reference
> to write *.S files before the asm-offset has been generated by make.

First of all, people should stop writing assembly code when they
could use C instead.  The remaining (small!) parts of aseembler code
will need only a small number of offset definitions.  These should be
easy to handle.

Again: if you need larger numbers of such entries you are doing
something fundamentally wrong.  Reconsider your coding style.  What
exactly enforces you to use assembly?

Best regards,

Wolfgang Denk

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