| Message ID | 20250331230034.806124-1-willmcvicker@google.com |
|---|---|
| Headers | show |
| Series | Add module support for Arm64 Exynos MCT driver | expand |
On Mon, Mar 31, 2025 at 04:00:27PM -0700, Will McVicker wrote: > From: Donghoon Yu <hoony.yu@samsung.com> > > On Arm64 platforms the Exynos MCT driver can be built as a module. On > boot (and even after boot) the arch_timer is used as the clocksource and > tick timer. Once the MCT driver is loaded, it can be used as the wakeup > source for the arch_timer. > > Signed-off-by: Donghoon Yu <hoony.yu@samsung.com> > Signed-off-by: Youngmin Nam <youngmin.nam@samsung.com> > [Original commit from https://android.googlesource.com/kernel/gs/+/8a52a8288ec7d88ff78f0b37480dbb0e9c65bbfd] > Signed-off-by: Will McVicker <willmcvicker@google.com> > --- > drivers/clocksource/Kconfig | 3 +- > drivers/clocksource/exynos_mct.c | 47 +++++++++++++++++++++++++++----- > 2 files changed, 42 insertions(+), 8 deletions(-) [...] > +#ifdef MODULE > +static int exynos4_mct_probe(struct platform_device *pdev) > +{ > + struct device_node *np = pdev->dev.of_node; > + > + if (of_machine_is_compatible("samsung,exynos4412-mct")) Your root node compatible has "samsung,exynos4412-mct"!? In any case, add a data ptr to of_device_id table and then use the match data rather than comparing compatible strings again. > + return mct_init_ppi(np); > + > + return mct_init_spi(np); > +} > + > +static const struct of_device_id exynos4_mct_match_table[] = { > + { .compatible = "samsung,exynos4210-mct" }, > + { .compatible = "samsung,exynos4412-mct" }, > + {} > +}; > +MODULE_DEVICE_TABLE(of, exynos4_mct_match_table);
On 01/04/2025 01:00, Will McVicker wrote: > From: Donghoon Yu <hoony.yu@samsung.com> > > On Arm64 platforms the Exynos MCT driver can be built as a module. On > boot (and even after boot) the arch_timer is used as the clocksource and > tick timer. Once the MCT driver is loaded, it can be used as the wakeup > source for the arch_timer. > > Signed-off-by: Donghoon Yu <hoony.yu@samsung.com> > Signed-off-by: Youngmin Nam <youngmin.nam@samsung.com> > [Original commit from https://android.googlesource.com/kernel/gs/+/8a52a8288ec7d88ff78f0b37480dbb0e9c65bbfd] > Signed-off-by: Will McVicker <willmcvicker@google.com> > --- > drivers/clocksource/Kconfig | 3 +- > drivers/clocksource/exynos_mct.c | 47 +++++++++++++++++++++++++++----- > 2 files changed, 42 insertions(+), 8 deletions(-) > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > index 487c85259967..e5d9d8383607 100644 > --- a/drivers/clocksource/Kconfig > +++ b/drivers/clocksource/Kconfig > @@ -443,7 +443,8 @@ config ATMEL_TCB_CLKSRC > Support for Timer Counter Blocks on Atmel SoCs. > > config CLKSRC_EXYNOS_MCT > - bool "Exynos multi core timer driver" if COMPILE_TEST > + tristate "Exynos multi core timer driver" > + default y if ARCH_EXYNOS > depends on ARM || ARM64 > depends on ARCH_ARTPEC || ARCH_EXYNOS || COMPILE_TEST I am not sure if you actually tested it as module. On arm I cannot build it even: ERROR: modpost: "register_current_timer_delay" [drivers/clocksource/exynos_mct.ko] undefined! ERROR: modpost: "sched_clock_register" [drivers/clocksource/exynos_mct.ko] undefined! Best regards, Krzysztof
On 04/01/2025, Krzysztof Kozlowski wrote: > On 01/04/2025 01:00, Will McVicker wrote: > > From: Donghoon Yu <hoony.yu@samsung.com> > > > > On Arm64 platforms the Exynos MCT driver can be built as a module. On > > boot (and even after boot) the arch_timer is used as the clocksource and > > tick timer. Once the MCT driver is loaded, it can be used as the wakeup > > source for the arch_timer. > > > > Signed-off-by: Donghoon Yu <hoony.yu@samsung.com> > > Signed-off-by: Youngmin Nam <youngmin.nam@samsung.com> > > [Original commit from https://android.googlesource.com/kernel/gs/+/8a52a8288ec7d88ff78f0b37480dbb0e9c65bbfd] > > Signed-off-by: Will McVicker <willmcvicker@google.com> > > --- > > drivers/clocksource/Kconfig | 3 +- > > drivers/clocksource/exynos_mct.c | 47 +++++++++++++++++++++++++++----- > > 2 files changed, 42 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > > index 487c85259967..e5d9d8383607 100644 > > --- a/drivers/clocksource/Kconfig > > +++ b/drivers/clocksource/Kconfig > > @@ -443,7 +443,8 @@ config ATMEL_TCB_CLKSRC > > Support for Timer Counter Blocks on Atmel SoCs. > > > > config CLKSRC_EXYNOS_MCT > > - bool "Exynos multi core timer driver" if COMPILE_TEST > > + tristate "Exynos multi core timer driver" > > + default y if ARCH_EXYNOS > > depends on ARM || ARM64 > > depends on ARCH_ARTPEC || ARCH_EXYNOS || COMPILE_TEST > I am not sure if you actually tested it as module. On arm I cannot build > it even: > > ERROR: modpost: "register_current_timer_delay" > [drivers/clocksource/exynos_mct.ko] undefined! > ERROR: modpost: "sched_clock_register" > [drivers/clocksource/exynos_mct.ko] undefined! I tested with the gs101 ARM64 configuration. You're right it won't work with ARM32. Thanks for catching this! Since ARM32 architectures don't have the arch_timer, I'm not sure if we can actually support Exynos MCT as a module as you wouldn't have any available clocksource during boot. I'll update the Kconfig for v2 to handle this and make sure it works for ARM32. I'm guessing it'll work with something like: config CLKSRC_EXYNOS_MCT tristate "Exynos multi core timer driver" if ARM64 Regards, Will [...]
On 03/31/2025, John Stultz wrote: > On Mon, Mar 31, 2025 at 4:00 PM 'Will McVicker' via kernel-team > <kernel-team@android.com> wrote: > > > > From: Hosung Kim <hosung0.kim@samsung.com> > > > > The MCT local timers can be used as a per-cpu event timer. To prevent > > Can be used, or are used? If it's an option, is this change important > in both cases? > > > the timer interrupts from migrating to other CPUs, set the flag > > IRQF_PERCPU. > > Might be work expanding this a bit to clarify why the interrupts > migrating to other cpus is undesired. Let me dig into this further to figure out if the IP has a limitation where the interrupts need to be handled by the CPU the timer was triggered on or if this is just an optimization. Any chance you know this @Youngmin? Thanks, Will > > > Signed-off-by: Hosung Kim <hosung0.kim@samsung.com> > > [Original commit from https://android.googlesource.com/kernel/gs/+/03267fad19f093bac979ca78309483e9eb3a8d16] > > Signed-off-by: Will McVicker <willmcvicker@google.com> > > thanks! > -john
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 driver is used as the wakeup source for the arch_timer. 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://git.codelinaro.org/linaro/googlelt/pixelscripts/-/blob/clo/main/README.md?ref_type=heads 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 (3): of/irq: Export of_irq_count for modules clocksource/drivers/exynos_mct: Don't register as a sched_clock on arm64 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 | 55 ++++++++++++++++---- drivers/of/irq.c | 1 + 5 files changed, 51 insertions(+), 12 deletions(-)