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Subject[tip:smp/hotplug] clocksource/exynos_mct: Convert to hotplug state machine
Commit-ID:  d11b3a60fcc8c6e44dd370f1cf2738eb5bec7353
Gitweb: http://git.kernel.org/tip/d11b3a60fcc8c6e44dd370f1cf2738eb5bec7353
Author: Richard Cochran <rcochran@linutronix.de>
AuthorDate: Wed, 13 Jul 2016 17:17:05 +0000
Committer: Ingo Molnar <mingo@kernel.org>
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@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Kukjin Kim <kgene@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-samsung-soc@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153338.147940411@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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,
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