[U-Boot] [linux-sunxi] [RFC PATCH 8/8] sunxi: enable PSCI for A83T SoC

[Chen-Yu Tsai]

On Wed, Jun 7, 2017 at 2:50 PM, Maxime Ripard
<maxime.ripard at free-electrons.com> wrote:
> On Wed, Jun 07, 2017 at 11:47:24AM +0800, Chen-Yu Tsai wrote:
>> On Wed, Jun 7, 2017 at 11:40 AM, Icenowy Zheng <icenowy at aosc.io> wrote:
>> >
>> >
>> > 于 2017年6月7日 GMT+08:00 上午11:36:27, Chen-Yu Tsai <wens at csie.org> 写到:
>> >>On Wed, Jun 7, 2017 at 8:47 AM, Icenowy Zheng <icenowy at aosc.io> wrote:
>> >>> As we have now a basical implementation of PSCI for A83T, enable
>> >>> non-secure boot support and PSCI on A83T now.
>> >>>
>> >>> Signed-off-by: Icenowy Zheng <icenowy at aosc.io>
>> >>> ---
>> >>>  arch/arm/mach-sunxi/Kconfig | 4 ++++
>> >>>  1 file changed, 4 insertions(+)
>> >>>
>> >>> diff --git a/arch/arm/mach-sunxi/Kconfig
>> >>b/arch/arm/mach-sunxi/Kconfig
>> >>> index 7ced838d6a..31d29de428 100644
>> >>> --- a/arch/arm/mach-sunxi/Kconfig
>> >>> +++ b/arch/arm/mach-sunxi/Kconfig
>> >>> @@ -98,8 +98,12 @@ config MACH_SUN8I_A33
>> >>>  config MACH_SUN8I_A83T
>> >>>         bool "sun8i (Allwinner A83T)"
>> >>>         select CPU_V7
>> >>> +       select CPU_V7_HAS_NONSEC
>> >>> +       select CPU_V7_HAS_VIRT
>> >>> +       select ARCH_SUPPORT_PSCI
>> >>>         select SUNXI_GEN_SUN6I
>> >>>         select SUPPORT_SPL
>> >>> +       select ARMV7_BOOT_SEC_DEFAULT if OLD_SUNXI_KERNEL_COMPAT
>> >>
>> >>The kernel does not work yet. Please have it boot to secure by default
>> >>regardless of the kernel. We can have it boot non-secure once the
>> >>kernel
>> >>has been working for a reasonable amount of time.
>> >>
>> >>I don't want clueless users coming and asking why it suddenly stopped
>> >>working. This should be an experimental feature.
>> >
>> > Maybe you should send out the fix, and tag them to also apply to
>> > stable tree.
>> >
>> > GIC is really broken, UP systems only work by chance. We
>> > shouldn't depend on this behavior.
>>
>> As I previously explained, it is not the GIC that is broken. I believe
>> the GIC is working exactly as it is supposed to with regards to its
>> input signals.
>>
>> Allwinner's security extensions implementation simply does not properly
>> forward the AXI secure bit when the e-fuse's secure bit isn't burned.
>
> Is that on all revisions, or just the revB ?

It's the A80, but I'm guessing the same applies to the A83T. It's more
of a guess really, but I think it's a logical one. If the e-fuse isn't
programmed, the TZPC doesn't work, and access to all secure peripherals
still work, even from non-secure mode. The only one that does work is
the secure SRAM.

The GIC still has the banked secure/non-secure registers, just that all
cores access the secure bank, even when in non-secure mode. The workaround
is to use the alias set of non-secure registers in Linux.

I'm not about to waste one of my boards programming the e-fuse to find
out the hard way though. The CCU doesn't have a security setting. It
might as well be secure-only. If one sets the e-fuse and the SoC's
security extensions work as they're supposed to, then it will no longer
work with mainline Linux. Or any software we have for that matter.

Regards
ChenYu