clocksource/arm_arch_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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153336.048259040@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 26 insertions, 28 deletions

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5effd3027319..28bce3f4f81d 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -370,8 +370,10 @@ static bool arch_timer_has_nonsecure_ppi(void)
                 arch_timer_ppi[PHYS_NONSECURE_PPI]);
 }
 
-static int arch_timer_setup(struct clock_event_device *clk)
+static int arch_timer_starting_cpu(unsigned int cpu)
 {
+        struct clock_event_device *clk = this_cpu_ptr(arch_timer_evt);
+
         __arch_timer_setup(ARCH_CP15_TIMER, clk);
 
         enable_percpu_irq(arch_timer_ppi[arch_timer_uses_ppi], 0);
@@ -527,29 +529,14 @@ static void arch_timer_stop(struct clock_event_device *clk)
         clk->set_state_shutdown(clk);
 }
 
-static int arch_timer_cpu_notify(struct notifier_block *self,
-                                           unsigned long action, void *hcpu)
+static int arch_timer_dying_cpu(unsigned int cpu)
 {
-        /*
-         * Grab cpu pointer in each case to avoid spurious
-         * preemptible warnings
-         */
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_STARTING:
-                arch_timer_setup(this_cpu_ptr(arch_timer_evt));
-                break;
-        case CPU_DYING:
-                arch_timer_stop(this_cpu_ptr(arch_timer_evt));
-                break;
-        }
+        struct clock_event_device *clk = this_cpu_ptr(arch_timer_evt);
 
-        return NOTIFY_OK;
+        arch_timer_stop(clk);
+        return 0;
 }
 
-static struct notifier_block arch_timer_cpu_nb = {
-        .notifier_call = arch_timer_cpu_notify,
-};
-
 #ifdef CONFIG_CPU_PM
 static unsigned int saved_cntkctl;
 static int arch_timer_cpu_pm_notify(struct notifier_block *self,
@@ -570,11 +557,21 @@ static int __init arch_timer_cpu_pm_init(void)
 {
         return cpu_pm_register_notifier(&arch_timer_cpu_pm_notifier);
 }
+
+static void __init arch_timer_cpu_pm_deinit(void)
+{
+        WARN_ON(cpu_pm_unregister_notifier(&arch_timer_cpu_pm_notifier));
+}
+
 #else
 static int __init arch_timer_cpu_pm_init(void)
 {
         return 0;
 }
+
+static void __init arch_timer_cpu_pm_deinit(void)
+{
+}
 #endif
 
 static int __init arch_timer_register(void)
@@ -621,22 +618,23 @@ static int __init arch_timer_register(void)
                 goto out_free;
         }
 
-        err = register_cpu_notifier(&arch_timer_cpu_nb);
-        if (err)
-                goto out_free_irq;
-
         err = arch_timer_cpu_pm_init();
         if (err)
                 goto out_unreg_notify;
 
-        /* Immediately configure the timer on the boot CPU */
-        arch_timer_setup(this_cpu_ptr(arch_timer_evt));
 
+        /* Register and immediately configure the timer on the boot CPU */
+        err = cpuhp_setup_state(CPUHP_AP_ARM_ARCH_TIMER_STARTING,
+                                "AP_ARM_ARCH_TIMER_STARTING",
+                                arch_timer_starting_cpu, arch_timer_dying_cpu);
+        if (err)
+                goto out_unreg_cpupm;
         return 0;
 
+out_unreg_cpupm:
+        arch_timer_cpu_pm_deinit();
+
 out_unreg_notify:
-        unregister_cpu_notifier(&arch_timer_cpu_nb);
-out_free_irq:
         free_percpu_irq(arch_timer_ppi[arch_timer_uses_ppi], arch_timer_evt);
         if (arch_timer_has_nonsecure_ppi())
                 free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],