[U-Boot] [PATCH 06/10] sunxi: Group cpu core related controls together

[Marc Zyngier]

On 24/05/16 17:06, Chen-Yu Tsai wrote:
> On Tue, May 24, 2016 at 4:15 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
>> On 23/05/16 13:41, Chen-Yu Tsai wrote:
>>> Instead of listing individual registers for controls to each processor
>>> core, list them as an array of registers. This makes accessing controls
>>> by core index easier.
>>>
>>> Also rename "cpucfg_sun6i.h" (which was unused anyway) to the more generic
>>> "cpucfg.h".
>>>
>>> Signed-off-by: Chen-Yu Tsai <wens at csie.org>
>>> ---
>>>  .../asm/arch-sunxi/{cpucfg_sun6i.h => cpucfg.h}    | 31 +++++++++-------------
>>>  arch/arm/include/asm/arch-sunxi/prcm.h             |  6 ++---
>>>  2 files changed, 14 insertions(+), 23 deletions(-)
>>>  rename arch/arm/include/asm/arch-sunxi/{cpucfg_sun6i.h => cpucfg.h} (69%)
>>>
>>> diff --git a/arch/arm/include/asm/arch-sunxi/cpucfg_sun6i.h b/arch/arm/include/asm/arch-sunxi/cpucfg.h
>>> similarity index 69%
>>> rename from arch/arm/include/asm/arch-sunxi/cpucfg_sun6i.h
>>> rename to arch/arm/include/asm/arch-sunxi/cpucfg.h
>>> index e2a29cb1818e..b9084b3968cd 100644
>>> --- a/arch/arm/include/asm/arch-sunxi/cpucfg_sun6i.h
>>> +++ b/arch/arm/include/asm/arch-sunxi/cpucfg.h
>>> @@ -11,33 +11,26 @@
>>>
>>>  #ifndef __ASSEMBLY__
>>>
>>> +struct sunxi_cpucfg_cpu {
>>> +     u32 rst;                /* base + 0x0 */
>>> +     u32 ctrl;               /* base + 0x4 */
>>> +     u32 status;             /* base + 0x8 */
>>> +     u8 res[0x34];           /* base + 0xc */
>>> +};
>>
>> Please use the "packed" attribute. Even if you declared your structure
>> in a way that makes sure no padding will be introduced, this also serves
>> as a reminder that this is not your usual memory.
>>
>> Same goes for the other structures in the file.
> 
> OK.
> 
> Somewhat related, it seems we use (struct foo*) for accessing registers
> in U-boot, while in the kernel we use (void * + some offset). Could someone
> explain the trade-offs or preferences on this? struct foo doesn't work in
> assembly afaik.

I personally hate the use of structures to access MMIO, because it gives
people the idea that they can manipulate this just like memory. Which
means that they are probably going to miss crucial barriers (on ARM), or
do something completely wrong on some other architectures (have a look
at SPARC and its ASIs).

But that's just my personal taste, and I don't mind people doing one or
the other in code that I don't have to maintain... ;-)

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...