Re: [PATCH] ArmPkg/ArmLib: remove indirection layer from timer register accessors

[Ryan Harkin <ryan.harkin@linaro.org>]

On 20 January 2017 at 14:35, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> On 20 January 2017 at 14:32, Ryan Harkin <ryan.harkin@linaro.org> wrote:
>> Hi Ard,
>>
>> On 20 January 2017 at 12:06, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
>>> The generic timer support libraries call the actual system register
>>> accessor function via a single pair of functions ArmArchTimerReadReg()
>>> and ArmArchTimerWriteReg(), which take an enum to argument to identify
>>> the register, and return output values by pointer reference.
>>>
>>> Since these functions are never called with a non-immediate argument,
>>> we can simply replace each invocation with the underlying system register
>>> accessor instead. This is mostly functionally equivalent, with the
>>> exception of the bounds check for the enum (which is pointless given the
>>> fact that we never pass a variable), the check for the presence of the
>>> architected timer (which only makes sense for ARMv7, but is highly unlikely
>>> to vary between platforms that are similar enough to run the same firmware
>>> image), and a check for enum values that refer to the HYP view of the timer,
>>> which we never referred to anywhere in the code in the first place.
>>>
>>> So get rid of the middle man, and update the ArmGenericTimerPhyCounterLib
>>> and ArmGenericTimerVirtCounterLib implementations to call the system
>>> register accessors directly.
>>>
>>> Contributed-under: TianoCore Contribution Agreement 1.0
>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>
>> Are there any other patches needed to get this working?
>>
>> I've just applied it to the head of EDK2 [1] and I get this error when
>> building for TC2, FVP and Juno:
>>
>> Building ... /linaro/platforms/uefi/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.inf
>> [AARCH64]
>> /linaro/platforms/uefi/edk2/ArmPkg/Library/ArmGenericTimerPhyCounterLib/ArmGenericTimerPhyCounterLib.c:
>> In function 'ArmGenericTimerSetTimerFreq':
>> /linaro/platforms/uefi/edk2/ArmPkg/Library/ArmGenericTimerPhyCounterLib/ArmGenericTimerPhyCounterLib.c:51:19:
>> error: 'CntFrq' undeclared (first use in this function)
>>    ArmWriteCntFrq (CntFrq);
>>                    ^
>> /linaro/platforms/uefi/edk2/ArmPkg/Library/ArmGenericTimerPhyCounterLib/ArmGenericTimerPhyCounterLib.c:51:19:
>> note: each undeclared identifier is reported only once for each
>> function it appears in
>> GNUmakefile:304: recipe for target
>> '/linaro/platforms/uefi/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/AARCH64/ArmPkg/Library/ArmGenericTimerPhyCounterLib/ArmGenericTimerPhyCounterLib/OUTPUT/ArmGenericTimerPhyCounterLib.obj'
>> failed
>> make: *** [/linaro/platforms/uefi/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/AARCH64/ArmPkg/Library/ArmGenericTimerPhyCounterLib/ArmGenericTimerPhyCounterLib/OUTPUT/ArmGenericTimerPhyCounterLib.obj]
>> Error 1
>>
>
>
> Oops! Poor testing on my part: that should be FreqInHz not CntFrq

Naughty! ;-)

Okay, so with that change, it works on TC2, FVP Foundation & AEMv8 and
Juno R0/R1/R2:

Tested-by: Ryan Harkin <ryan.harkin@linaro.org>