Re: [PATCH v2 6/7] clocksource/drivers/exynos_mct: Add module support

Daniel Lezcano
2025-04-15T17:12:33Z

Hi Will,

On Wed, Apr 02, 2025 at 04:33:57PM -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.

From a previous thread where there is no answer:

https://lore.kernel.org/all/c1e8abec-680c-451d-b5df-f687291aa413@linaro.org/

I don't feel comfortable with changing the clocksource / clockevent drivers to
a module for the reasons explained in the aforementionned thread.

Before this could be accepted, I really need a strong acked-by from Thomas

Thanks

-- Daniel

> 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 | 49 +++++++++++++++++++++++++++-----
> 2 files changed, 44 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 487c85259967..e89373827c3a 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" 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 62febeb4e1de..8943274378be 100644
> --- a/drivers/clocksource/exynos_mct.c
> +++ b/drivers/clocksource/exynos_mct.c
> @@ -15,9 +15,11 @@
> #include <linux/cpu.h>
> #include <linux/delay.h>
> #include <linux/percpu.h>
> +#include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_irq.h>
> #include <linux/of_address.h>
> +#include <linux/platform_device.h>
> #include <linux/clocksource.h>
> #include <linux/sched_clock.h>
>
> @@ -241,7 +243,7 @@ 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
> @@ -511,7 +513,7 @@ 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 +541,7 @@ 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)
> @@ -652,7 +654,7 @@ 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};
> @@ -700,15 +702,48 @@ 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);
> }
> +
> +#ifdef MODULE
> +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,
> + },
> +};
> +module_platform_driver(exynos4_mct_driver);
> +#else
> TIMER_OF_DECLARE(exynos4210, "samsung,exynos4210-mct", mct_init_spi);
> TIMER_OF_DECLARE(exynos4412, "samsung,exynos4412-mct", mct_init_ppi);
> +#endif
> +
> +MODULE_DESCRIPTION("Exynos Multi Core Timer Driver");
> +MODULE_LICENSE("GPL");
> --
> 2.49.0.472.ge94155a9ec-goog
>

--

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