[U-Boot] [PATCH 4/5] arm: Provide common PSCI based reset handler

[Alexander Graf]

> Am 18.08.2016 um 05:44 schrieb Simon Glass <sjg at chromium.org>:
> 
> Hi Alex,
> 
>> On 16 August 2016 at 13:08, Alexander Graf <agraf at suse.de> wrote:
>> Most armv8 systems have PSCI support enabled in EL3, either through
>> ARM Trusted Firmware or other firmware.
>> 
>> On these systems, we do not need to implement system reset manually,
>> but can instead rely on higher level firmware to deal with it.
>> 
>> The exclude list seems excessive right now, but NXP is working on
>> providing an in-tree PSCI implementation, so that all NXP systems
>> can eventually use PSCI as well.
>> 
>> Signed-off-by: Alexander Graf <agraf at suse.de>
>> ---
>> arch/arm/cpu/armv8/Kconfig   | 18 ++++++++++++++++++
>> arch/arm/cpu/armv8/fwcall.c  |  7 +++++++
>> arch/arm/mach-meson/board.c  |  5 -----
>> board/xilinx/zynqmp/zynqmp.c |  5 -----
>> 4 files changed, 25 insertions(+), 10 deletions(-)
> 
> Reviewed-by: Simon Glass <sjg at chromium.org>
> 
>> 
>> diff --git a/arch/arm/cpu/armv8/Kconfig b/arch/arm/cpu/armv8/Kconfig
>> index 7e1fc4c..cd2d9bb 100644
>> --- a/arch/arm/cpu/armv8/Kconfig
>> +++ b/arch/arm/cpu/armv8/Kconfig
>> @@ -21,4 +21,22 @@ config ARMV8_SPIN_TABLE
>>            - Reserve the code for the spin-table and the release address
>>              via a /memreserve/ region in the Device Tree.
>> 
>> +config PSCI_RESET
>> +       bool "Use PSCI for reset and shutdown"
>> +       default y
>> +       depends on !ARCH_EXYNOS7 && !ARCH_BCM283X && !TARGET_LS2080A_EMU && \
>> +                  !TARGET_LS2080A_SIMU && !TARGET_LS2080AQDS && \
>> +                  !TARGET_LS2080ARDB && !TARGET_LS1012AQDS && \
>> +                  !TARGET_LS1012ARDB && !TARGET_LS1012AFRDM && \
>> +                  !TARGET_LS1043ARDB && !ARCH_UNIPHIER && !ARCH_SNAPDRAGON && \
>> +                  !TARGET_S32V234EVB
> 
> Will this break new systems that are added?

I would word it differently - it will gently push new systems into the right direction ;). With PSCI available, Linux SMP will "just work" too.

The worst that can happen is that someone enables a nee system which does not provide PSCI. In that case we have non-working reboot and shutdown handlers. The alternative would be no reboot and shutdown handlers (which is a fatal panic on Linux for example), so we're not worse off imho.


Alex