[PATCH v5 0/4] clocksource: Add module support for timer drivers

[PATCH v5 0/4] clocksource: Add module support for timer drivers

[Zhipeng Wang]

This patch series enables SoC-specific timer drivers to be built as 
loadable modules for Generic Kernel Image (GKI). SoC-specific timer 
drivers provide always-on broadcast timers that complement the ARM 
architectural timer.

This series is based on the previous MediaTek timer modularization work:
Link: https://lore.kernel.org/all/20230517022557.24388-1-walter.chang@mediatek.com/

The series includes:
1. Export necessary functions from clocksource/mmio
2. Remove __init markings from timer-of to support modules
3. Convert MediaTek timer driver to support module build
4. Convert i.MX TPM timer driver to support module build

Testing performed:
- Built and tested on i.MX8ULP platform
- Built and tested on MediaTek platform
- Verified both built-in and module configurations
- Confirmed timer functionality in both configurations

Changes in v5:
- Conditionally compile delay timer and sched_clock registration
  only when built-in (!MODULE) to avoid calling __init functions
  from module code.

Changes in v4:
- Refined the cover letter introduction to clarify that SoC-specific
  timers act as always-on broadcast timers complementing the ARM
  architectural timer.
- Expanded "GKI" to "Generic Kernel Image (GKI)" in commit messages.
- No functional changes to the code.

Changes in v3:
- Reworded summary line for timer-mediatek driver as suggested.
- Improved commit message formatting (line wrapping).
- No functional changes to the code.

Changes in v2:
- Added Signed-off-by from submitter (Zhipeng Wang) to all patches
  as requested by reviewers

Changes in v1:
- Fixed 'unsigned' to 'unsigned int' in clocksource_mmio_init()
- Changed MODULE_LICENSE from "GPL v2" to "GPL" for mediatek driver
- Added i.MX TPM timer driver module support

Chun-Hung Wu (3):
  clocksource/drivers/mmio: Export clocksource_mmio_init()
  clocksource/drivers/timer-of: Remove __init markings
  clocksource/drivers/timer-mediatek: Convert timer-mediatek to a
    loadable module

Jindong Yue (1):
  clocksource/drivers/imx-tpm: Support building imx-tpm driver as module

 drivers/clocksource/Kconfig          |  4 +--
 drivers/clocksource/mmio.c           |  8 +++---
 drivers/clocksource/timer-imx-tpm.c  | 40 ++++++++++++++++++++++++----
 drivers/clocksource/timer-mediatek.c | 33 +++++++++++++++++++++++
 drivers/clocksource/timer-of.c       | 23 ++++++++--------
 drivers/clocksource/timer-of.h       |  6 ++---
 6 files changed, 90 insertions(+), 24 deletions(-)


base-commit: bc47b2e823914966c15a09422f8fc3aa98d34c1b
-- 
2.34.1

[PATCH v5 1/4] clocksource/drivers/mmio: Export clocksource_mmio_init()

[Zhipeng Wang]

From: Chun-Hung Wu <chun-hung.wu@mediatek.com>

Export clocksource_mmio_init() and clocksource_mmio_readl_up()
to support building clocksource driver as module,
such as timer-mediatek.c.

Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Signed-off-by: Walter Chang <walter.chang@mediatek.com>
Acked-by: John Stultz <jstultz@google.com>
Signed-off-by: Zhipeng Wang <zhipeng.wang_1@nxp.com>
---
 drivers/clocksource/mmio.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
index cd5fbf49ac29..238bf29db6f7 100644
--- a/drivers/clocksource/mmio.c
+++ b/drivers/clocksource/mmio.c
@@ -21,6 +21,7 @@ u64 clocksource_mmio_readl_up(struct clocksource *c)
 {
 	return (u64)readl_relaxed(to_mmio_clksrc(c)->reg);
 }
+EXPORT_SYMBOL_GPL(clocksource_mmio_readl_up);
 
 u64 clocksource_mmio_readl_down(struct clocksource *c)
 {
@@ -46,9 +47,9 @@ u64 clocksource_mmio_readw_down(struct clocksource *c)
  * @bits:	Number of valid bits
  * @read:	One of clocksource_mmio_read*() above
  */
-int __init clocksource_mmio_init(void __iomem *base, const char *name,
-	unsigned long hz, int rating, unsigned bits,
-	u64 (*read)(struct clocksource *))
+int clocksource_mmio_init(void __iomem *base, const char *name,
+			  unsigned long hz, int rating, unsigned int bits,
+			  u64 (*read)(struct clocksource *))
 {
 	struct clocksource_mmio *cs;
 
@@ -68,3 +69,4 @@ int __init clocksource_mmio_init(void __iomem *base, const char *name,
 
 	return clocksource_register_hz(&cs->clksrc, hz);
 }
+EXPORT_SYMBOL_GPL(clocksource_mmio_init);
-- 
2.34.1

[PATCH v5 2/4] clocksource/drivers/timer-of: Remove __init markings

[Zhipeng Wang]

From: Chun-Hung Wu <chun-hung.wu@mediatek.com>

Remove __init markings to allow timer drivers
can be compiled as modules.

Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Signed-off-by: Walter Chang <walter.chang@mediatek.com>
Acked-by: John Stultz <jstultz@google.com>
Signed-off-by: Zhipeng Wang <zhipeng.wang_1@nxp.com>
---
 drivers/clocksource/timer-of.c | 23 ++++++++++++-----------
 drivers/clocksource/timer-of.h |  6 +++---
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/clocksource/timer-of.c b/drivers/clocksource/timer-of.c
index 420202bf76e4..b7c186dc83da 100644
--- a/drivers/clocksource/timer-of.c
+++ b/drivers/clocksource/timer-of.c
@@ -19,7 +19,7 @@
  *
  * Free the irq resource
  */
-static __init void timer_of_irq_exit(struct of_timer_irq *of_irq)
+static void timer_of_irq_exit(struct of_timer_irq *of_irq)
 {
 	struct timer_of *to = container_of(of_irq, struct timer_of, of_irq);
 
@@ -41,8 +41,8 @@ static __init void timer_of_irq_exit(struct of_timer_irq *of_irq)
  *
  * Returns 0 on success, < 0 otherwise
  */
-static __init int timer_of_irq_init(struct device_node *np,
-				    struct of_timer_irq *of_irq)
+static int timer_of_irq_init(struct device_node *np,
+			     struct of_timer_irq *of_irq)
 {
 	int ret;
 	struct timer_of *to = container_of(of_irq, struct timer_of, of_irq);
@@ -82,7 +82,7 @@ static __init int timer_of_irq_init(struct device_node *np,
  *
  * Disables and releases the refcount on the clk
  */
-static __init void timer_of_clk_exit(struct of_timer_clk *of_clk)
+static void timer_of_clk_exit(struct of_timer_clk *of_clk)
 {
 	of_clk->rate = 0;
 	clk_disable_unprepare(of_clk->clk);
@@ -98,8 +98,8 @@ static __init void timer_of_clk_exit(struct of_timer_clk *of_clk)
  *
  * Returns 0 on success, < 0 otherwise
  */
-static __init int timer_of_clk_init(struct device_node *np,
-				    struct of_timer_clk *of_clk)
+static int timer_of_clk_init(struct device_node *np,
+			     struct of_timer_clk *of_clk)
 {
 	int ret;
 
@@ -137,13 +137,13 @@ static __init int timer_of_clk_init(struct device_node *np,
 	goto out;
 }
 
-static __init void timer_of_base_exit(struct of_timer_base *of_base)
+static void timer_of_base_exit(struct of_timer_base *of_base)
 {
 	iounmap(of_base->base);
 }
 
-static __init int timer_of_base_init(struct device_node *np,
-				     struct of_timer_base *of_base)
+static int timer_of_base_init(struct device_node *np,
+			      struct of_timer_base *of_base)
 {
 	of_base->base = of_base->name ?
 		of_io_request_and_map(np, of_base->index, of_base->name) :
@@ -156,7 +156,7 @@ static __init int timer_of_base_init(struct device_node *np,
 	return 0;
 }
 
-int __init timer_of_init(struct device_node *np, struct timer_of *to)
+int timer_of_init(struct device_node *np, struct timer_of *to)
 {
 	int ret = -EINVAL;
 	int flags = 0;
@@ -200,6 +200,7 @@ int __init timer_of_init(struct device_node *np, struct timer_of *to)
 		timer_of_base_exit(&to->of_base);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(timer_of_init);
 
 /**
  * timer_of_cleanup - release timer_of resources
@@ -208,7 +209,7 @@ int __init timer_of_init(struct device_node *np, struct timer_of *to)
  * Release the resources that has been used in timer_of_init().
  * This function should be called in init error cases
  */
-void __init timer_of_cleanup(struct timer_of *to)
+void timer_of_cleanup(struct timer_of *to)
 {
 	if (to->flags & TIMER_OF_IRQ)
 		timer_of_irq_exit(&to->of_irq);
diff --git a/drivers/clocksource/timer-of.h b/drivers/clocksource/timer-of.h
index 01a2c6b7db06..367d7023c623 100644
--- a/drivers/clocksource/timer-of.h
+++ b/drivers/clocksource/timer-of.h
@@ -65,9 +65,9 @@ static inline unsigned long timer_of_period(struct timer_of *to)
 	return to->of_clk.period;
 }
 
-extern int __init timer_of_init(struct device_node *np,
-				struct timer_of *to);
+extern int timer_of_init(struct device_node *np,
+			 struct timer_of *to);
 
-extern void __init timer_of_cleanup(struct timer_of *to);
+extern void timer_of_cleanup(struct timer_of *to);
 
 #endif
-- 
2.34.1

[PATCH v5 3/4] clocksource/drivers/timer-mediatek: Convert timer-mediatek to a loadable module

[Zhipeng Wang]

From: Chun-Hung Wu <chun-hung.wu@mediatek.com>

Convert the timer-mediatek driver into a loadable module so that it
can register an always-on timer as the tick_broadcast_device on
MediaTek SoCs. This helps support GKI(Generic Kernel Image) modular
configurations.

Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Signed-off-by: Walter Chang <walter.chang@mediatek.com>
Tested-by: Walter Chang <walter.chang@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Signed-off-by: Zhipeng Wang <zhipeng.wang_1@nxp.com>
---
 drivers/clocksource/Kconfig          |  2 +-
 drivers/clocksource/timer-mediatek.c | 33 ++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index fd9112706545..2112efb85029 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -488,7 +488,7 @@ config SYS_SUPPORTS_SH_CMT
 	bool
 
 config MTK_TIMER
-	bool "Mediatek timer driver" if COMPILE_TEST
+	tristate "MediaTek timer driver"
 	depends on HAS_IOMEM
 	select TIMER_OF
 	select CLKSRC_MMIO
diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c
index 7bcb4a3f26fb..4ad4bac6f34b 100644
--- a/drivers/clocksource/timer-mediatek.c
+++ b/drivers/clocksource/timer-mediatek.c
@@ -13,6 +13,9 @@
 #include <linux/clocksource.h>
 #include <linux/interrupt.h>
 #include <linux/irqreturn.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
 #include <linux/sched_clock.h>
 #include <linux/slab.h>
 #include "timer-of.h"
@@ -337,5 +340,35 @@ static int __init mtk_gpt_init(struct device_node *node)
 
 	return 0;
 }
+
+#ifndef MODULE
 TIMER_OF_DECLARE(mtk_mt6577, "mediatek,mt6577-timer", mtk_gpt_init);
 TIMER_OF_DECLARE(mtk_mt6765, "mediatek,mt6765-timer", mtk_syst_init);
+#else
+static int mtk_timer_probe(struct platform_device *pdev)
+{
+	int (*timer_init)(struct device_node *node);
+	struct device_node *np = pdev->dev.of_node;
+
+	timer_init = of_device_get_match_data(&pdev->dev);
+	return timer_init(np);
+}
+
+static const struct of_device_id mtk_timer_match_table[] = {
+	{ .compatible = "mediatek,mt6577-timer", .data = mtk_gpt_init },
+	{ .compatible = "mediatek,mt6765-timer", .data = mtk_syst_init },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver mtk_timer_driver = {
+	.probe = mtk_timer_probe,
+	.driver = {
+		.name = "mediatek-timer",
+		.of_match_table = mtk_timer_match_table,
+	},
+};
+module_platform_driver(mtk_timer_driver);
+
+MODULE_DESCRIPTION("MediaTek Timer driver");
+MODULE_LICENSE("GPL");
+#endif
-- 
2.34.1

[PATCH v5 4/4] clocksource/drivers/imx-tpm: Support building imx-tpm driver as module

[Zhipeng Wang]

From: Jindong Yue <jindong.yue@nxp.com>

Change defconfig as tristate type and add platform driver
to support building it as a module.

Signed-off-by: Jindong Yue <jindong.yue@nxp.com>
Signed-off-by: Zhipeng Wang <zhipeng.wang_1@nxp.com>
---
 drivers/clocksource/Kconfig         |  2 +-
 drivers/clocksource/timer-imx-tpm.c | 40 +++++++++++++++++++++++++----
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 2112efb85029..1ba3e9bca3db 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -613,7 +613,7 @@ config CLKSRC_IMX_GPT
 	select CLKSRC_MMIO
 
 config CLKSRC_IMX_TPM
-	bool "Clocksource using i.MX TPM" if COMPILE_TEST
+	tristate "Clocksource using i.MX TPM"
 	depends on (ARM || ARM64) && HAVE_CLK
 	select CLKSRC_MMIO
 	select TIMER_OF
diff --git a/drivers/clocksource/timer-imx-tpm.c b/drivers/clocksource/timer-imx-tpm.c
index 92c025b70eb6..1d593b6f0c37 100644
--- a/drivers/clocksource/timer-imx-tpm.c
+++ b/drivers/clocksource/timer-imx-tpm.c
@@ -8,6 +8,8 @@
 #include <linux/clocksource.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
 #include <linux/sched_clock.h>
 
 #include "timer-of.h"
@@ -66,7 +68,7 @@ static inline unsigned long tpm_read_counter(void)
 	return readl(timer_base + TPM_CNT);
 }
 
-#if defined(CONFIG_ARM)
+#if defined(CONFIG_ARM) && !defined(MODULE)
 static struct delay_timer tpm_delay_timer;
 
 static unsigned long tpm_read_current_timer(void)
@@ -152,9 +154,9 @@ static struct timer_of to_tpm = {
 	},
 };
 
-static int __init tpm_clocksource_init(void)
+static int tpm_clocksource_init(void)
 {
-#if defined(CONFIG_ARM)
+#if defined(CONFIG_ARM) && !defined(MODULE)
 	tpm_delay_timer.read_current_timer = &tpm_read_current_timer;
 	tpm_delay_timer.freq = timer_of_rate(&to_tpm) >> 3;
 	register_current_timer_delay(&tpm_delay_timer);
@@ -171,7 +173,7 @@ static int __init tpm_clocksource_init(void)
 				     clocksource_mmio_readl_up);
 }
 
-static void __init tpm_clockevent_init(void)
+static void tpm_clockevent_init(void)
 {
 	clockevents_config_and_register(&to_tpm.clkevt,
 					timer_of_rate(&to_tpm) >> 3,
@@ -180,7 +182,7 @@ static void __init tpm_clockevent_init(void)
 					1));
 }
 
-static int __init tpm_timer_init(struct device_node *np)
+static int tpm_timer_init(struct device_node *np)
 {
 	struct clk *ipg;
 	int ret;
@@ -241,4 +243,32 @@ static int __init tpm_timer_init(struct device_node *np)
 
 	return tpm_clocksource_init();
 }
+#ifdef MODULE
+static int tpm_timer_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+
+	return tpm_timer_init(np);
+}
+
+static const struct of_device_id tpm_timer_match_table[] = {
+	{ .compatible = "fsl,imx7ulp-tpm" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tpm_timer_match_table);
+
+static struct platform_driver tpm_timer_driver = {
+	.probe		= tpm_timer_probe,
+	.driver		= {
+		.name	= "tpm-timer",
+		.of_match_table = tpm_timer_match_table,
+	},
+};
+module_platform_driver(tpm_timer_driver);
+
+#else
 TIMER_OF_DECLARE(imx7ulp, "fsl,imx7ulp-tpm", tpm_timer_init);
+#endif
+
+MODULE_DESCRIPTION("i.MX TPM Timer Driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1

Re: [PATCH v5 3/4] clocksource/drivers/timer-mediatek: Convert timer-mediatek to a loadable module

[Frank Li]

From: Frank Li (AI-BOT) <frank.li@nxp.com>

> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>

AI: Include headers should be sorted alphabetically. "of_device.h" should come
before "platform_device.h".

Frank

Re: [PATCH v5 3/4] clocksource/drivers/timer-mediatek: Convert timer-mediatek to a loadable module

[Frank Li]

On Fri, Mar 06, 2026 at 11:51:39AM -0500, Frank Li wrote:
> From: Frank Li (AI-BOT) <frank.li@nxp.com>
>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
>
> AI: Include headers should be sorted alphabetically. "of_device.h" should come
> before "platform_device.h".

Please forget it. Sorry for annoise.

Frank
>
> Frank