[PATCH v2 0/7] Add module support for Arm64 Exynos MCT driver

Tue Apr 8 12:57:57 PDT 2025

On 04/04/2025, Youngmin Nam wrote:
> On Wed, Apr 02, 2025 at 04:33:51PM -0700, Will McVicker wrote:
> > This series adds support to build the Arm64 Exynos MCT driver as a module. This
> > is only possible on Arm64 SoCs since they can use the Arm architected timer as
> > the clocksource. Once the Exynos MCT module is loaded and the device probes,
> > the MCT is used as the wakeup source for the arch_timer to ensure the device
> > can wakeup from the "c2" idle state.
> > 
> > These patches are originally from the downstream Pixel 6 (gs101) kernel found
> > at [1] and have been adapted for upstream. Not only has the Exynos MCT driver
> > been shipping as a module in the field with Android, but I've also tested this
> > seris with the upstream kernel on my Pixel 6 Pro.
> > 
> > Thanks,
> > Will
> > 
> > Note1, instructions to build and flash a Pixel 6 device with the upstream kernel
> > can be found at [2].
> > 
> > Note2, this series is based off of linux-next/master commit 405e2241def8 ("Add
> > linux-next specific files for 20250331").
> > 
> > [1] https://android.googlesource.com/kernel/gs/+log/refs/heads/android-gs-raviole-5.10-android12-d1
> > [2] https://protect2.fireeye.com/v1/url?k=d287bb1b-b30cae21-d2863054-74fe4860008a-f0cb7ae29f3b1b85&q=1&e=4e8467a4-13da-4dd4-a8fd-4ddfc38e89b4&u=https%3A%2F%2Fgit.codelinaro.org%2Flinaro%2Fgooglelt%2Fpixelscripts%2F-%2Fblob%2Fclo%2Fmain%2FREADME.md%3Fref_type%3Dheads
> > 
> > Cc: Alim Akhtar <alim.akhtar at samsung.com>
> > Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
> > Cc: Donghoon Yu <hoony.yu at samsung.com>
> > Cc: Hosung Kim <hosung0.kim at samsung.com>
> > Cc: kernel-team at android.com
> > Cc: linux-arm-kernel at lists.infradead.org
> > Cc: linux-kernel at vger.kernel.org
> > Cc: Rob Herring <robh at kernel.org>
> > Cc: Saravana Kannan <saravanak at google.com>
> > Cc: Thomas Gleixner <tglx at linutronix.de>
> > Cc: Youngmin Nam <youngmin.nam at samsung.com>
> > Cc: Peter Griffin <peter.griffin at linaro.org>
> > Cc: Tudor Ambarus <tudor.ambarus at linaro.org>
> > Cc: André Draszik <andre.draszik at linaro.org>
> > Cc: Will Deacon <will at kernel.org>
> > Cc: Conor Dooley <conor+dt at kernel.org>
> > Cc: Krzysztof Kozlowski <krzk at kernel.org>
> > Cc: linux-samsung-soc at vger.kernel.org
> > 
> > ---
> > Changes in v2:
> > - Re-worked patch v1 5 based on Rob Herring's review to use the compatible data
> >   for retrieving the mct_init function pointer.
> > - Updated the Kconfig logic to disallow building the Exynos MCT driver as
> >   a module for ARM32 configurations based on Krzysztof Kozlowski's findings.
> > - Added comments and clarified commit messages in patches 1 and 2 based on
> >   reviews from John Stultz and Youngmin Nam.
> > - Fixed an issue found during testing that resulted in the device getting
> >   stuck on boot. This is included in v2 as patch 5.
> > - Collected *-by tags
> > - Rebased to the latest linux-next/master.
> > 
> > ---
> > Donghoon Yu (1):
> >   clocksource/drivers/exynos_mct: Add module support
> > 
> > Hosung Kim (1):
> >   clocksource/drivers/exynos_mct: Set local timer interrupts as percpu
> > 
> > Will Deacon (1):
> >   arm64: dts: exynos: gs101: Add 'local-timer-stop' to cpuidle nodes
> > 
> > Will McVicker (4):
> >   of/irq: Export of_irq_count for modules
> >   clocksource/drivers/exynos_mct: Don't register as a sched_clock on
> >     arm64
> >   clocksource/drivers/exynos_mct: Fix uninitialized irq name warning
> >   arm64: exynos: Drop select CLKSRC_EXYNOS_MCT
> > 
> >  arch/arm64/Kconfig.platforms                 |  1 -
> >  arch/arm64/boot/dts/exynos/google/gs101.dtsi |  3 +
> >  drivers/clocksource/Kconfig                  |  3 +-
> >  drivers/clocksource/exynos_mct.c             | 73 ++++++++++++++++----
> >  drivers/of/irq.c                             |  1 +
> >  5 files changed, 67 insertions(+), 14 deletions(-)
> > 
> > -- 
> > 2.49.0.472.ge94155a9ec-goog
> > 
> > 
> 
> Hi Will.
> 
> I tested this series on a E850-96(Exynos3830 based) board and it's working as a moudle.
> 
> # dmesg | grep mct
> [7.376224] clocksource: mct-frc: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 73510017198 ns
> 
> # lsmod | grep exynos_mct
> exynos_mct             12288  0
> 
> # cat /sys/devices/system/clocksource/clocksource0/current_clocksource
> arch_sys_counter
> # cat /sys/devices/system/clockevents/clockevent0/current_device
> arch_sys_timer
> 
> # cat /proc/interrupts 
>         CPU0    CPU1    CPU2    CPU3    CPU4    CPU5    CPU6    CPU7
>  12:    2566    2752    2467    4026    3372    2822    2115    3227 GIC-0  27 Level     arch_timer
> ...
>  77:       0       0       0       0       0       0       0       0 GIC-0 235 Level     mct_comp_irq
>  78:       0       0       0       0       0       0       0       0 GIC-0 239 Level     mct_tick0
>  79:       0       0       0       0       0       0       0       0 GIC-0 240 Level     mct_tick1
>  80:       0       0       0       0       0       0       0       0 GIC-0 241 Level     mct_tick2
>  81:       0       0       0       0       0       0       0       0 GIC-0 242 Level     mct_tick3
>  82:       0       0       0       0       0       0       0       0 GIC-0 243 Level     mct_tick4
>  83:       0       0       0       0       0       0       0       0 GIC-0 244 Level     mct_tick5
>  84:       0       0       0       0       0       0       0       0 GIC-0 245 Level     mct_tick6
>  85:       0       0       0       0       0       0       0       0 GIC-0 246 Level     mct_tick7
> 
> Reviewed-by: Youngmin Nam <youngmin.nam at samsung.com>
> Tested-by: Youngmin Nam <youngmin.nam at samsung.com>
> 
> Thanks,
> Youngmin

Thanks Youngmin for the reviews and testing!

Regards,
Will