[PATCH 05/14] at91: use structure to store the current soc

[Andrew Victor]

hi,

>> If this eventually reduces code size then I think it is useful, but
>> otherwise I'm not sure I see the point?
> It's on purpose as the dbgu physical address is not at the same place
> so read the other register really does not impact the chip but if we do it
> later duting the boot or the life to the kernel it's an other story
>
> so the split between __cpu_is and cpu_is is necessarly
>
> all of this work is in preparation to allow multiple soc in the same kernel
> that's also why I map the system controller the same way on all at91 arm9

The cpu_is() or__cpu_is() perform a at91_sys_read() of one of the DBGU
registers.

But the address of the DBGU differs between CPUs regardless if you map
the system controller the same:
   at572d940hf.h:#define AT91_DBGU	(0xfffff200 - AT91_BASE_SYS)
   at91cap9.h:#define AT91_DBGU	(0xffffee00 - AT91_BASE_SYS)
   at91rm9200.h:#define AT91_DBGU	(0xfffff200 - AT91_BASE_SYS)
   at91sam9260.h:#define AT91_DBGU	(0xfffff200 - AT91_BASE_SYS)
   at91sam9261.h:#define AT91_DBGU	(0xfffff200 - AT91_BASE_SYS)
   at91sam9263.h:#define AT91_DBGU	(0xffffee00 - AT91_BASE_SYS)
   at91sam9g45.h:#define AT91_DBGU	(0xffffee00 - AT91_BASE_SYS)
   at91sam9rl.h:#define AT91_DBGU	(0xfffff200 - AT91_BASE_SYS)

So I don't see how you can "detect" the CPU without first knowing
which CPU and therefore where the DBGU register is anyway.
And probing different addresses for a value is not an acceptable solution.


While having a single kernel image that supports AT91 processors is a
good goal, the soc.h is a totally unnecessary complication.
I can't think of any situation where an AT91 board.c file doesn't know
what processor it has.

So instead of :
   boardXYZ-init ->  at91_initialize() --> magic-cpu-detection -->
at91XX_initialize()
just do:
   boardXYZ-init  -> at91XX_initialize()

And soc.c's not really removing much code duplication...  most of the
code in there is the newly-added early_platform_devices.


Regards,
  Andrew Victor