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>

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 0d18dd4..41840d0 100644 (file)
--- 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..7ad8a7e 100644 (file)
--- 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,