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

[Daniel Lezcano]

Hi Will,

On Wed, Apr 02, 2025 at 04:33:57PM -0700, Will McVicker wrote:
> From: Donghoon Yu <hoony.yu@xxxxxxxxxxx>
> 
> 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@xxxxxxxxxx/

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@xxxxxxxxxxx>
> Signed-off-by: Youngmin Nam <youngmin.nam@xxxxxxxxxxx>
> [original commit from https://android.googlesource.com/kernel/gs/+/8a52a8288ec7d88ff78f0b37480dbb0e9c65bbfd]
> Signed-off-by: Will McVicker <willmcvicker@xxxxxxxxxx>
> ---
>  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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