[U-Boot] [PATCH 1/2] armv8: add hooks for all cache-wide operations

[Stephen Warren]

On 10/18/2016 10:23 AM, Simon Glass wrote:
> Hi Stephen,
>
> On 17 October 2016 at 15:35, Stephen Warren <swarren at wwwdotorg.org> wrote:
>> From: Stephen Warren <swarren at nvidia.com>
>>
>> SoC-specific logic may be required for all forms of cache-wide
>> operations; invalidate and flush of both dcache and icache (note that
>> only 3 of the 4 possible combinations make sense, since the icache never
>> contains dirty lines). This patch adds an optional hook for all
>> implemented cache-wide operations, and renames the one existing hook to
>> better represent exactly which operation it is implementing. A dummy
>> no-op implementation of each hook is provided. These dummy
>> implementations are moved into C code, since there's no need to
>> implement them in assembly.
>>
>> Signed-off-by: Stephen Warren <swarren at nvidia.com>
>> ---
>>  arch/arm/cpu/armv8/cache.S                   |  6 ------
>>  arch/arm/cpu/armv8/cache_v8.c                | 23 ++++++++++++++++++++---
>>  arch/arm/cpu/armv8/fsl-layerscape/lowlevel.S |  4 ++--
>>  arch/arm/include/asm/system.h                |  5 ++++-
>>  arch/arm/mach-tegra/tegra186/cache.c         |  2 +-
>>  5 files changed, 27 insertions(+), 13 deletions(-)
>>
>
> I think we should have a proper interface for this stuff rather than
> weak functions. Maybe we need a linker-list approach, or a cache
> uclass?

What's improper about this interface? Presumably we could argue that no 
function in the entire of U-Boot be called by symbol name, which doesn't 
seem useful.

I'm not sure exactly what you envisage by a linker-list approach. Can 
you provide some background? I understand how the linker can construct 
list of objects/implementations/..., but that doesn't seem useful here 
since there's a known-ahead-of-time single implementation of these 
functions in a single build of U-Boot.

A cache uclass seems like /massive/ overkill, especially since I'd 
expect these very low-level functions to be required well before any 
higher level code like DM/classes/... to be available.