Re: [PATCH v4 0/8] ARM: sun9i: SMP and CPU hotplug support

[Chen-Yu Tsai]

Hi Nicolas, Dave,

On Wed, Jan 17, 2018 at 4:46 PM, Chen-Yu Tsai <wens@xxxxxxxx> wrote:
> This is v4 of my sun9i SMP/hotplug support series which was started
> over two years ago [1]. We've tried to implement PSCI for both the A80
> and A83T. Results were not promising. The issue is that these two chips
> have a broken security extensions implementation. If a specific bit is
> not burned in its e-fuse, most if not all security protections don't
> work [2]. Even worse, non-secure access to the GIC become secure. This
> requires a crazy workaround in the GIC driver which probably doesn't work
> in all cases [3].
>
> Version 3 completely did away with the MCPM framework, instead just
> implementing a set of smp_ops. Most of the code from the previous
> version was reused, so the structure still has some traces of MCPM.
> As our hardware has CCI-400, we still need some sort of MMU/cache
> disabled trampoline code to enable cache coherency. Code for this
> was adapted from the MCPM framework. This and the entry code are done
> in inline assembly. Most of the other sunxi-specific code is derived
> from Allwinner code and documentation, with some references to the
> other MCPM implementations, as well as the Cortex's Technical Reference
> Manuals for the power sequencing stuff.
>
> In version 4, all traces of MCPM have been removed, except in the
> comments for atttributing code sources. Thumb2 mode is also fixed.
> It failed due to an unaligned word access.

Any more comments on this series? Or is it OK for you guys now that
there are no traces of MCPM? :)

We'll merge this series later this week for 4.17 if nothing else.

Thanks
ChenYu

>
> Hope we can get this version merged. A83T SMP support will be built on
> it.
>
> Regards
> ChenYu
>
> Changes since v3:
>   - Renamed all "MCPM" occurrences to "MC_SMP", as the MCPM framework
>     is no longer used
>   - Thumb2 mode fixed
>
> Changes since v2:
>   - Do away with the MCPM framework, directly implement smp_ops
>   - Some debug messages were clarified
>   - New ARCH_SUNXI_MCPM Kconfig symbol for this feature
>
> Changes since v1:
>
>   - Leading zeroes for device node addresses removed
>   - Added device tree binding for SMP SRAM
>   - Simplified Kconfig options
>   - Switched to SPDX license identifier
>   - Map CPU to device tree node and check compatible to see if it's
>     Cortex-A15 or Cortex-A7
>   - Fix incorrect CPUCFG cluster status macro that prevented cluster
>     0 L2 cache WFI detection
>   - Fixed reversed bit for turning off cluster
>   - Put cluster in reset before turning off power (or it hangs)
>   - Added dedicated workqueue for turning off power to cpus and clusters
>   - Request CPUCFG and SRAM MMIO ranges
>   - Some comments fixed or added
>   - Some debug messages added
>
> [1] http://www.spinics.net/lists/arm-kernel/msg418350.html
> [2] https://lists.denx.de/pipermail/u-boot/2017-June/294637.html
> [3] https://github.com/wens/linux/commit/c48654c1f737116e7a7660183c8c74fa91970528
>
> Chen-Yu Tsai (8):
>   ARM: sun9i: Support SMP bring-up on A80
>   ARM: dts: sun9i: Add CCI-400 device nodes for A80
>   ARM: dts: sun9i: Add CPUCFG device node for A80 dtsi
>   ARM: dts: sun9i: Add PRCM device node for the A80 dtsi
>   ARM: sun9i: smp: Support CPU/cluster power down and hotplugging for
>     cpu1~7
>   dt-bindings: ARM: sunxi: Document A80 SoC secure SRAM usage by SMP
>     hotplug
>   ARM: sun9i: smp: Support cpu0 hotplug
>   ARM: dts: sun9i: Add secure SRAM node used for SMP hotplug
>
>  .../devicetree/bindings/arm/sunxi/smp-sram.txt     |  44 ++
>  arch/arm/boot/dts/sun9i-a80.dtsi                   |  75 ++
>  arch/arm/mach-sunxi/Kconfig                        |   7 +
>  arch/arm/mach-sunxi/Makefile                       |   1 +
>  arch/arm/mach-sunxi/mc_smp.c                       | 791 +++++++++++++++++++++
>  5 files changed, 918 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/sunxi/smp-sram.txt
>  create mode 100644 arch/arm/mach-sunxi/mc_smp.c
>
> --
> 2.15.1
>