[U-Boot] [PATCH 1/3] ARmv7: Add a soc_init hook to start.S

[Hans de Goede]

Hi,

On 22-01-15 22:03, Tom Rini wrote:
> On Thu, Jan 22, 2015 at 08:10:06PM +0100, Hans de Goede wrote:
>> Hi,
>>
>> On 22-01-15 17:20, Tom Rini wrote:
>>> On Wed, Jan 21, 2015 at 09:03:25PM +0100, Hans de Goede wrote:
>>>
>>>> On some SoCs / ARMv7 CPU cores we need to do some setup before enabling the
>>>> icache, etc. Add a soc_init hook with a weak default which just calls
>>>> cpu_init_cp15.
>>>>
>>>> This way different implementations can be provided to do some extra work
>>>> before or after cpu_init_cp15, or completely replacing cpu_init_cp15.
>>>>
>>>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>>>> ---
>>>>   arch/arm/cpu/armv7/start.S | 18 +++++++++++++++++-
>>>>   1 file changed, 17 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
>>>> index fdc05b9..9882b20 100644
>>>> --- a/arch/arm/cpu/armv7/start.S
>>>> +++ b/arch/arm/cpu/armv7/start.S
>>>> @@ -64,7 +64,7 @@ reset:
>>>>
>>>>   	/* the mask ROM code should have PLL and others stable */
>>>>   #ifndef CONFIG_SKIP_LOWLEVEL_INIT
>>>> -	bl	cpu_init_cp15
>>>> +	bl	soc_init
>>>>   	bl	cpu_init_crit
>>>>   #endif
>>>
>>> I like the direction here.  And I want to make sure I get the sunxi
>>> direction right here too (as I agree with the need / desire for boot0 +
>>> U-Boot to be a valid combination).  I think we can take this a step
>>> farther.  cpu_init_crit (on armv7) is basically a call to s_init().
>>>
>>> For am33xx (and I bet but need to do and test omap3+) we can, with
>>> Simon's patch to let us move stack to DDR a tiny bit later, in the SPL
>>> case make s_init empty, which just leaves us with (with your patch)
>>> soc_init.  Is there some way we can put all of this together in a
>>> function?
>>
>> You mean essentially call s_init here and have s_init call cpu_init_cp15
>> I guess we could do that, but it would require auditing all existing armv7
>> users of s_init. This may require me to rethink how / when I do timer &
>> gpio init etc. for u-boot.bin on sunxi, but that should not be a (big)
>> problem.
>
> Basically.  From my first pass audit of s_init, it's either empty
> (Kona), sunxi, or omap/etc so I get to deal with it.  And the default
> soc_init would just be the call to cpu_init_cp15 as you have it and we
> drop the lowlevel_init hurdles.

Ok, so what you're suggesting is a patch which:

1) Changes:

#ifndef CONFIG_SKIP_LOWLEVEL_INIT
	bl	cpu_init_cp15
    	bl	cpu_init_crit
#endif

Into:

#ifndef CONFIG_SKIP_LOWLEVEL_INIT
	bl	lowlevel_init
#endif

Which will setup the stack and then call the s_init C function

2) Adds a weak default s_init which calls cpu_init_cp15

3) Patch all existing s_init functions to call cpu_init_cp15
before doing anything else.


And then in follow up patches we can:

4) Drop cpu_init_crit

5) Cleanup some s_init functions (this will be left to the individual
SoC maintainers)

I think that is a good idea, Albert what do you think about this ?

Regards,

Hans