[tip:smp/hotplug] clocksource/exynos_mct: Convert to hotplug state machine

[tip-bot for Richard Cochran]

Commit-ID:  d11b3a60fcc8c6e44dd370f1cf2738eb5bec7353
Gitweb:     http://git.kernel.org/tip/d11b3a60fcc8c6e44dd370f1cf2738eb5bec7353
Author:     Richard Cochran <rcochran@xxxxxxxxxxxxx>
AuthorDate: Wed, 13 Jul 2016 17:17:05 +0000
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 15 Jul 2016 10:41:44 +0200

clocksource/exynos_mct: Convert to hotplug state machine

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Richard Cochran <rcochran@xxxxxxxxxxxxx>
Signed-off-by: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
Cc: Kukjin Kim <kgene@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-samsung-soc@xxxxxxxxxxxxxxx
Cc: rt@xxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20160713153338.147940411@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 drivers/clocksource/exynos_mct.c | 46 +++++++++++-----------------------------
 include/linux/cpuhotplug.h       |  1 +
 2 files changed, 13 insertions(+), 34 deletions(-)

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 0d18dd4b..41840d0 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -443,10 +443,11 @@ static irqreturn_t exynos4_mct_tick_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static int exynos4_local_timer_setup(struct mct_clock_event_device *mevt)
+static int exynos4_mct_starting_cpu(unsigned int cpu)
 {
+	struct mct_clock_event_device *mevt =
+		per_cpu_ptr(&percpu_mct_tick, cpu);
 	struct clock_event_device *evt = &mevt->evt;
-	unsigned int cpu = smp_processor_id();
 
 	mevt->base = EXYNOS4_MCT_L_BASE(cpu);
 	snprintf(mevt->name, sizeof(mevt->name), "mct_tick%d", cpu);
@@ -480,8 +481,10 @@ static int exynos4_local_timer_setup(struct mct_clock_event_device *mevt)
 	return 0;
 }
 
-static void exynos4_local_timer_stop(struct mct_clock_event_device *mevt)
+static int exynos4_mct_dying_cpu(unsigned int cpu)
 {
+	struct mct_clock_event_device *mevt =
+		per_cpu_ptr(&percpu_mct_tick, cpu);
 	struct clock_event_device *evt = &mevt->evt;
 
 	evt->set_state_shutdown(evt);
@@ -491,39 +494,12 @@ static void exynos4_local_timer_stop(struct mct_clock_event_device *mevt)
 	} else {
 		disable_percpu_irq(mct_irqs[MCT_L0_IRQ]);
 	}
+	return 0;
 }
 
-static int exynos4_mct_cpu_notify(struct notifier_block *self,
-					   unsigned long action, void *hcpu)
-{
-	struct mct_clock_event_device *mevt;
-
-	/*
-	 * Grab cpu pointer in each case to avoid spurious
-	 * preemptible warnings
-	 */
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_STARTING:
-		mevt = this_cpu_ptr(&percpu_mct_tick);
-		exynos4_local_timer_setup(mevt);
-		break;
-	case CPU_DYING:
-		mevt = this_cpu_ptr(&percpu_mct_tick);
-		exynos4_local_timer_stop(mevt);
-		break;
-	}
-
-	return NOTIFY_OK;
-}
-
-static struct notifier_block exynos4_mct_cpu_nb = {
-	.notifier_call = exynos4_mct_cpu_notify,
-};
-
 static int __init exynos4_timer_resources(struct device_node *np, void __iomem *base)
 {
 	int err, cpu;
-	struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick);
 	struct clk *mct_clk, *tick_clk;
 
 	tick_clk = np ? of_clk_get_by_name(np, "fin_pll") :
@@ -570,12 +546,14 @@ static int __init exynos4_timer_resources(struct device_node *np, void __iomem *
 		}
 	}
 
-	err = register_cpu_notifier(&exynos4_mct_cpu_nb);
+	/* Install hotplug callbacks which configure the timer on this CPU */
+	err = cpuhp_setup_state(CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
+				"AP_EXYNOS4_MCT_TIMER_STARTING",
+				exynos4_mct_starting_cpu,
+				exynos4_mct_dying_cpu);
 	if (err)
 		goto out_irq;
 
-	/* Immediately configure the timer on the boot CPU */
-	exynos4_local_timer_setup(mevt);
 	return 0;
 
 out_irq:
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index d24b0fc..7ad8a7e7 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -49,6 +49,7 @@ enum cpuhp_state {
 	CPUHP_AP_ARM_ARCH_TIMER_STARTING,
 	CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
 	CPUHP_AP_DUMMY_TIMER_STARTING,
+	CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
 	CPUHP_AP_ARM_TWD_STARTING,
 	CPUHP_AP_METAG_TIMER_STARTING,
 	CPUHP_AP_QCOM_TIMER_STARTING,