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[34.82.88.80]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2946e241d65sm59444195ad.107.2025.10.24.08.53.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Oct 2025 08:53:52 -0700 (PDT) Date: Fri, 24 Oct 2025 15:53:48 +0000 From: William McVicker To: Marek Szyprowski Cc: Russell King , Catalin Marinas , Will Deacon , Daniel Lezcano , Thomas Gleixner , Krzysztof Kozlowski , Alim Akhtar , Ingo Molnar , Peter Griffin , Youngmin Nam , Donghoon Yu , Rob Herring , Saravana Kannan , John Stultz , Tudor Ambarus , =?iso-8859-1?Q?Andr=E9?= Draszik , Conor Dooley , linux-samsung-soc@vger.kernel.org, kernel-team@android.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 6/7] clocksource/drivers/exynos_mct: Add module support Message-ID: References: <20251023205257.2029526-1-willmcvicker@google.com> <20251023205257.2029526-7-willmcvicker@google.com> <40d3f3c9-7526-440b-9dbd-7ead22c8562a@samsung.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <40d3f3c9-7526-440b-9dbd-7ead22c8562a@samsung.com> On 10/24/2025, Marek Szyprowski wrote: > On 23.10.2025 22:52, Will McVicker wrote: > > From: Donghoon Yu > > > > 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 > > Signed-off-by: Youngmin Nam > > Signed-off-by: Will McVicker > > Signed-off-by: Daniel Lezcano > > [original commit from https://android.googlesource.com/kernel/gs/+/8a52a8288ec7d88ff78f0b37480dbb0e9c65bbfd] > > Reviewed-by: Youngmin Nam # AOSP -> Linux port > > Tested-by: Youngmin Nam # AOSP -> Linux port > > --- > > drivers/clocksource/Kconfig | 3 +- > > drivers/clocksource/exynos_mct.c | 56 +++++++++++++++++++++++++++----- > > 2 files changed, 49 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > > index ffcd23668763..9450cfaf982f 100644 > > --- a/drivers/clocksource/Kconfig > > +++ b/drivers/clocksource/Kconfig > > @@ -451,7 +451,8 @@ 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" if ARM64 > > + default y if ARCH_EXYNOS || COMPILE_TEST > > depends on ARM || ARM64 > > depends on ARCH_ARTPEC || ARCH_EXYNOS || COMPILE_TEST > > help > > diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c > > index fece6bbc190e..a87caf3928ef 100644 > > --- a/drivers/clocksource/exynos_mct.c > > +++ b/drivers/clocksource/exynos_mct.c > > @@ -15,9 +15,11 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > +#include > > #include > > #include > > > > @@ -217,6 +219,7 @@ static struct clocksource mct_frc = { > > .mask = CLOCKSOURCE_MASK(32), > > .flags = CLOCK_SOURCE_IS_CONTINUOUS, > > .resume = exynos4_frc_resume, > > + .owner = THIS_MODULE, > > }; > > > > /* > > @@ -241,7 +244,7 @@ static cycles_t exynos4_read_current_timer(void) > > } > > #endif > > > > -static int __init exynos4_clocksource_init(bool frc_shared) > > +static int exynos4_clocksource_init(bool frc_shared) > > { > > /* > > * When the frc is shared, the main processor should have already > > @@ -336,6 +339,7 @@ static struct clock_event_device mct_comp_device = { > > .set_state_oneshot = mct_set_state_shutdown, > > .set_state_oneshot_stopped = mct_set_state_shutdown, > > .tick_resume = mct_set_state_shutdown, > > + .owner = THIS_MODULE, > > }; > > > > static irqreturn_t exynos4_mct_comp_isr(int irq, void *dev_id) > > @@ -476,6 +480,7 @@ static int exynos4_mct_starting_cpu(unsigned int cpu) > > evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | > > CLOCK_EVT_FEAT_PERCPU; > > evt->rating = MCT_CLKEVENTS_RATING; > > + evt->owner = THIS_MODULE; > > > > exynos4_mct_write(TICK_BASE_CNT, mevt->base + MCT_L_TCNTB_OFFSET); > > > > @@ -511,7 +516,7 @@ static int exynos4_mct_dying_cpu(unsigned int cpu) > > return 0; > > } > > > > -static int __init exynos4_timer_resources(struct device_node *np) > > +static int exynos4_timer_resources(struct device_node *np) > > { > > struct clk *mct_clk, *tick_clk; > > > > @@ -539,7 +544,7 @@ static int __init exynos4_timer_resources(struct device_node *np) > > * @local_idx: array mapping CPU numbers to local timer indices > > * @nr_local: size of @local_idx array > > */ > > -static int __init exynos4_timer_interrupts(struct device_node *np, > > +static int exynos4_timer_interrupts(struct device_node *np, > > unsigned int int_type, > > const u32 *local_idx, > > size_t nr_local) > > @@ -653,7 +658,7 @@ static int __init exynos4_timer_interrupts(struct device_node *np, > > return err; > > } > > > > -static int __init mct_init_dt(struct device_node *np, unsigned int int_type) > > +static int mct_init_dt(struct device_node *np, unsigned int int_type) > > { > > bool frc_shared = of_property_read_bool(np, "samsung,frc-shared"); > > u32 local_idx[MCT_NR_LOCAL] = {0}; > > @@ -701,15 +706,48 @@ static int __init mct_init_dt(struct device_node *np, unsigned int int_type) > > return exynos4_clockevent_init(); > > } > > > > - > > -static int __init mct_init_spi(struct device_node *np) > > +static int mct_init_spi(struct device_node *np) > > { > > return mct_init_dt(np, MCT_INT_SPI); > > } > > > > -static int __init mct_init_ppi(struct device_node *np) > > +static int mct_init_ppi(struct device_node *np) > > { > > return mct_init_dt(np, MCT_INT_PPI); > > } > > -TIMER_OF_DECLARE(exynos4210, "samsung,exynos4210-mct", mct_init_spi); > > -TIMER_OF_DECLARE(exynos4412, "samsung,exynos4412-mct", mct_init_ppi); > > + > > +static int exynos4_mct_probe(struct platform_device *pdev) > > +{ > > + struct device *dev = &pdev->dev; > > + int (*mct_init)(struct device_node *np); > > + > > + mct_init = of_device_get_match_data(dev); > > + if (!mct_init) > > + return -EINVAL; > > + > > + return mct_init(dev->of_node); > > +} > > + > > +static const struct of_device_id exynos4_mct_match_table[] = { > > + { .compatible = "samsung,exynos4210-mct", .data = &mct_init_spi, }, > > + { .compatible = "samsung,exynos4412-mct", .data = &mct_init_ppi, }, > > + {} > > +}; > > +MODULE_DEVICE_TABLE(of, exynos4_mct_match_table); > > + > > +static struct platform_driver exynos4_mct_driver = { > > + .probe = exynos4_mct_probe, > > + .driver = { > > + .name = "exynos-mct", > > + .of_match_table = exynos4_mct_match_table, > > + }, > > +}; > > + > > +static __init int exynos_mct_init(void) > > +{ > > + return platform_driver_register(&exynos4_mct_driver); > > +} > > +module_init(exynos_mct_init); > > + > > +MODULE_DESCRIPTION("Exynos Multi Core Timer Driver"); > > +MODULE_LICENSE("GPL"); > > Sorry, but this still won't work on legacy ARM 32bit systems with MCT as > the only clocksource, which needs a driver available very early (that's > why it used TIMER_OF_DECLAREmacro). You need to make it conditional > under CONFIG_ARM: Can we rely on the bootloader to setup the MCT timer and then hand-off at boot once the driver is initialized? Daniel was working on a solution to transparently handle calling TIMER_OF_DECLARE() when a timer driver can be configured as both a module or built-in here: https://lore.kernel.org/all/20250625085715.889837-1-daniel.lezcano@linaro.org/ Daniel, do you have plans to finish that? In the meantime, can we go with the `#if CONFIG_ARM` solution? Thanks, Will