x86/apb_timer: Convert to hotplug state machine

Install the callbacks via the state machine. There is no setup just one
teardown callback. Remove the silly comment about the workqueue up dependency.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
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/20160713153335.625342983@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 11 insertions, 19 deletions

diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c
index cefacbad1531..456316f6c868 100644
--- a/arch/x86/kernel/apb_timer.c
+++ b/arch/x86/kernel/apb_timer.c
@@ -215,26 +215,18 @@ void apbt_setup_secondary_clock(void)
  * cpu timers during the offline process due to the ordering of notification.
  * the extra interrupt is harmless.
  */
-static int apbt_cpuhp_notify(struct notifier_block *n,
-                             unsigned long action, void *hcpu)
+static int apbt_cpu_dead(unsigned int cpu)
 {
-        unsigned long cpu = (unsigned long)hcpu;
         struct apbt_dev *adev = &per_cpu(cpu_apbt_dev, cpu);
 
-        switch (action & ~CPU_TASKS_FROZEN) {
-        case CPU_DEAD:
-                dw_apb_clockevent_pause(adev->timer);
-                if (system_state == SYSTEM_RUNNING) {
-                        pr_debug("skipping APBT CPU %lu offline\n", cpu);
-                } else {
-                        pr_debug("APBT clockevent for cpu %lu offline\n", cpu);
-                        dw_apb_clockevent_stop(adev->timer);
-                }
-                break;
-        default:
-                pr_debug("APBT notified %lu, no action\n", action);
+        dw_apb_clockevent_pause(adev->timer);
+        if (system_state == SYSTEM_RUNNING) {
+                pr_debug("skipping APBT CPU %u offline\n", cpu);
+        } else {
+                pr_debug("APBT clockevent for cpu %u offline\n", cpu);
+                dw_apb_clockevent_stop(adev->timer);
         }
-        return NOTIFY_OK;
+        return 0;
 }
 
 static __init int apbt_late_init(void)
@@ -242,9 +234,8 @@ static __init int apbt_late_init(void)
         if (intel_mid_timer_options == INTEL_MID_TIMER_LAPIC_APBT ||
                 !apb_timer_block_enabled)
                 return 0;
-        /* This notifier should be called after workqueue is ready */
-        hotcpu_notifier(apbt_cpuhp_notify, -20);
-        return 0;
+        return cpuhp_setup_state(CPUHP_X86_APB_DEAD, "X86_APB_DEAD", NULL,
+                                 apbt_cpu_dead);
 }
 fs_initcall(apbt_late_init);
 #else
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 8c190a85af6e..3e719ba44fbe 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -13,6 +13,7 @@ enum cpuhp_state {
         CPUHP_PERF_POWER,
         CPUHP_PERF_SUPERH,
         CPUHP_X86_HPET_DEAD,
+        CPUHP_X86_APB_DEAD,
         CPUHP_WORKQUEUE_PREP,
         CPUHP_NOTIFY_PREPARE,
         CPUHP_BRINGUP_CPU,