clocksource/arm_global_timer: 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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maxime Coquelin <maxime.coquelin@st.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel@stlinux.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153338.062741642@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c
index 2a9ceb6e93f92b8dd44451c76972ce7f49d5ec6f..8da03298f844f386b81c08f3bc12228fcab340ab 100644 (file)
--- a/drivers/clocksource/arm_global_timer.c
+++ b/drivers/clocksource/arm_global_timer.c
@@ -165,9 +165,9 @@ static irqreturn_t gt_clockevent_interrupt(int irq, void *dev_id)
        return IRQ_HANDLED;
 }
 
-static int gt_clockevents_init(struct clock_event_device *clk)
+static int gt_starting_cpu(unsigned int cpu)
 {
-       int cpu = smp_processor_id();
+       struct clock_event_device *clk = this_cpu_ptr(gt_evt);
 
        clk->name = "arm_global_timer";
        clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
@@ -186,10 +186,13 @@ static int gt_clockevents_init(struct clock_event_device *clk)
        return 0;
 }
 
-static void gt_clockevents_stop(struct clock_event_device *clk)
+static int gt_dying_cpu(unsigned int cpu)
 {
+       struct clock_event_device *clk = this_cpu_ptr(gt_evt);
+
        gt_clockevent_shutdown(clk);
        disable_percpu_irq(clk->irq);
+       return 0;
 }
 
 static cycle_t gt_clocksource_read(struct clocksource *cs)
@@ -252,24 +255,6 @@ static int __init gt_clocksource_init(void)
        return clocksource_register_hz(&gt_clocksource, gt_clk_rate);
 }
 
-static int gt_cpu_notify(struct notifier_block *self, unsigned long action,
-                        void *hcpu)
-{
-       switch (action & ~CPU_TASKS_FROZEN) {
-       case CPU_STARTING:
-               gt_clockevents_init(this_cpu_ptr(gt_evt));
-               break;
-       case CPU_DYING:
-               gt_clockevents_stop(this_cpu_ptr(gt_evt));
-               break;
-       }
-
-       return NOTIFY_OK;
-}
-static struct notifier_block gt_cpu_nb = {
-       .notifier_call = gt_cpu_notify,
-};
-
 static int __init global_timer_of_register(struct device_node *np)
 {
        struct clk *gt_clk;
@@ -325,18 +310,14 @@ static int __init global_timer_of_register(struct device_node *np)
                goto out_free;
        }
 
-       err = register_cpu_notifier(&gt_cpu_nb);
-       if (err) {
-               pr_warn("global-timer: unable to register cpu notifier.\n");
-               goto out_irq;
-       }
-
-       /* Immediately configure the timer on the boot CPU */
+       /* Register and immediately configure the timer on the boot CPU */
        err = gt_clocksource_init();
        if (err)
                goto out_irq;
        
-       err = gt_clockevents_init(this_cpu_ptr(gt_evt));
+       err = cpuhp_setup_state(CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
+                               "AP_ARM_GLOBAL_TIMER_STARTING",
+                               gt_starting_cpu, gt_dying_cpu);
        if (err)
                goto out_irq;
 

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 201a2e23bc49a0cee56c2db65f728840db6ab004..d24b0fc2f88d940aceff51442c2ae6929997b142 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -47,6 +47,7 @@ enum cpuhp_state {
        CPUHP_AP_PERF_ARM_STARTING,
        CPUHP_AP_ARM_L2X0_STARTING,
        CPUHP_AP_ARM_ARCH_TIMER_STARTING,
+       CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
        CPUHP_AP_DUMMY_TIMER_STARTING,
        CPUHP_AP_ARM_TWD_STARTING,
        CPUHP_AP_METAG_TIMER_STARTING,