[U-Boot] [PATCH V4 05/11] ARM: OMAP: Change set_pl310_ctrl_reg to be generic

[Nishanth Menon]

On Thu, Mar 5, 2015 at 3:36 PM, Tom Rini <trini at konsulko.com> wrote:
> On Thu, Mar 05, 2015 at 11:49:05AM -0600, Nishanth Menon wrote:
>> On 03/05/2015 08:00 AM, Matt Porter wrote:
>> > On Tue, Mar 03, 2015 at 04:26:22PM -0600, Nishanth Menon wrote:
>> >> set_pl310_ctrl_reg does use the Secure Monitor Call (SMC) to setup
>> >> PL310 control register, however, that is something that is generic
>> >> enough to be used for OMAP5 generation of processors as well. The only
>> >> difference being the service being invoked for the function.
>> >>
>> >> So, convert the service to a macro and use a generic name (same as
>> >> that used in Linux for some consistency). While at that, also add a
>> >> data barrier which is necessary as per recommendation.
>> >>
>> >> While at this, switch over to smc #0 instead of handcoded assembly.
>> >> To ensure gcc compatibility, steal the strategy used by Linux kernel
>> >> for sec extension builds (NOTE: we no longer use '-march=armv5' as the
>> >> legacy comment claims).
>> >
>> > Hi Nishanth,
>> >
>> > I applied this series with fuzz and fixed a minor conflict on master. I
>> > ran into a build issue for omap3 beagle with the sec extension scheme on
>> > the gcc version 4.7.4 (Ubuntu/Linaro 4.7.4-2ubuntu1) toolchain:
>> >
>> >  arm-linux-gnueabi-gcc
>> > -Wp,-MD,arch/arm/cpu/armv7/omap3/.lowlevel_init.o.d  -nostdinc -isystem
>> > /usr/lib/gcc-cross/arm-linux-gnueabi/4.7/include -Iinclude  -I../include
>> > -I../arch/arm/include -include ../include/linux/kconfig.h -D__KERNEL__
>> > -D__UBOOT__ -DCONFIG_SYS_TEXT_BASE=0x80100000 -D__ASSEMBLY__ -g
>> > -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux
>> > -mword-relocations -march=armv7-a -mno-unaligned-access
>> > -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float
>> > -pipe   -c -o arch/arm/cpu/armv7/omap3/lowlevel_init.o
>> > ../arch/arm/cpu/armv7/omap3/lowlevel_init.S
>> >
>> > ../arch/arm/cpu/armv7/omap-common/lowlevel_init.S: Assembler messages:
>> > ../arch/arm/cpu/armv7/omap-common/lowlevel_init.S:34: Error: selected
>> > processor does not support ARM mode `smc #0'
>> >
>> > I've worked around this for the moment by placing an explicit
>> > .arch_extension sec in lowlevel_init.S but hopefully you have some
>> > thoughts on why those flags don't seem to be picked up. I'll continue
>> > to take a look at it in the meantime.
>> >
>>
>>
>> Uggh.. this is weird. I had considered ".arch_extension sec in
>> lowlevel_init.S"
>>
>> > +plus_sec := $(call as-instr,.arch_extension sec,+sec)
>> > +AFLAGS_lowlevel_init.o       :=-Wa,-march=armv7-a$(plus_sec)
>>
>> seems to be what we have in kernel and seems to do the job for me on
>> $ arm-linux-gnueabi-gcc --version
>> arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
>>
>> $ git clean -fdx; make omap3_beagle_defconfig;
>> make V=1 arch/arm/cpu/armv7/omap-common/lowlevel_init.o
>>
>> with gcc 4.6:
>> arm-linux-gnueabi-gcc
>> -Wp,-MD,arch/arm/cpu/armv7/omap-common/.lowlevel_init.o.d  -nostdinc
>> -isystem /usr/lib/gcc/arm-linux-gnueabi/4.6/include -Iinclude
>> -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__
>> -D__UBOOT__ -DCONFIG_SYS_TEXT_BASE=0x80100000  -D__ASSEMBLY__ -g
>> -D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux
>> -mword-relocations  -march=armv7-a  -mno-unaligned-access
>> -ffunction-sections -fdata-sections -fno-common -ffixed-r9
>> -msoft-float  -pipe   -Wa,-march=armv7-a+sec   -c -o
>> arch/arm/cpu/armv7/omap-common/lowlevel_init.o
>> arch/arm/cpu/armv7/omap-common/lowlevel_init.S
>>
>>
>> with gcc 4.7:
>> arm-linux-gnueabi-gcc
>> -Wp,-MD,arch/arm/cpu/armv7/omap-common/.lowlevel_init.o.d  -nostdinc
>> -isystem /usr/lib/gcc-cross/arm-linux-gnueabi/4.7/include -Iinclude
>> -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__
>> -D__UBOOT__ -DCONFIG_SYS_TEXT_BASE=0x80100000  -D__ASSEMBLY__ -g
>> -D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux
>> -mword-relocations  -march=armv7-a  -mno-unaligned-access
>> -ffunction-sections -fdata-sections -fno-common -ffixed-r9
>> -msoft-float  -pipe  -Wa,-march=armv7-a   -c -o
>> arch/arm/cpu/armv7/omap-common/lowlevel_init.o
>> arch/arm/cpu/armv7/omap-common/lowlevel_init.S
>> arch/arm/cpu/armv7/omap-common/lowlevel_init.S: Assembler messages:
>> arch/arm/cpu/armv7/omap-common/lowlevel_init.S:34: Error: selected
>> processor does not support ARM mode `smc #0'
>> make[1]: *** [arch/arm/cpu/armv7/omap-common/lowlevel_init.o] Error 1
>> make: *** [arch/arm/cpu/armv7/omap-common/lowlevel_init.o] Error 2
>>
>> I thought I stole the exact code from kernel, but as you can probably
>> see -march=armv7-a+sec was generated for gcc 4.6 but -march=armv7-a
>> without +sec for gcc 4.7!
>>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-omap2/Makefile#n44
>>
>> It will be nice to have a solution that works on gcc 4.4 and above..
>> if we want to ignore gcc 4.4, then we can embed ".arch_extension sec
>> in lowlevel_init.S"
>>
>> https://gcc.gnu.org/ml/gcc-help/2012-07/msg00181.html
>
> Sigh.  I guess I'll give up on getting rid of the hand-crafted smc #0
> call, it's being more troulbe than it's worth.  Thanks for digging into
> it tho!

Alright, I will handcraft the smc code back in and keep us gcc safe
:D... will wait till we figure out what the heck i screwed up[1] in
the cpuid detect logic before i post a new rev. Sadly, i have'nt found
a board that kind of matches what Matt has :(.

[1] http://lists.denx.de/pipermail/u-boot/2015-March/207313.html
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Regards,
Nishanth Menon