[PATCH v6 5/6] clocksource/drivers/exynos_mct: Add module support for ARM64

[Will McVicker <willmcvicker@google.com>]

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>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
[original commit from https://android.googlesource.com/kernel/gs/+/8a52a8288ec7d88ff78f0b37480dbb0e9c65bbfd]
Reviewed-by: Youngmin Nam <youngmin.nam@samsung.com> # AOSP -> Linux port
Tested-by: Youngmin Nam <youngmin.nam@samsung.com> # AOSP -> Linux port
Signed-off-by: Will McVicker <willmcvicker@google.com>
---
 drivers/clocksource/Kconfig      |  3 +-
 drivers/clocksource/exynos_mct.c | 62 ++++++++++++++++++++++++++++----
 2 files changed, 57 insertions(+), 8 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..55ce1d0b648e 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>
 
@@ -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 +706,58 @@ 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 CONFIG_ARM
+/* Note, legacy ARM 32-bit systems depend on the MCT as the only clocksource
+ * which requires this driver to be initialized very early. We need to keep this
+ * special condition until we can transparently support modular and early init
+ * timers.
+ */
 TIMER_OF_DECLARE(exynos4210, "samsung,exynos4210-mct", mct_init_spi);
 TIMER_OF_DECLARE(exynos4412, "samsung,exynos4412-mct", mct_init_ppi);
+#else
+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");
+#endif /* CONFIG_ARM */
-- 
2.52.0.rc2.455.g230fcf2819-goog