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>

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5effd30273192d7b6e9c367061200aa1d7079e79..28bce3f4f81d6aa56840657169c0842461f9f515 100644 (file)
--- 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],

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 5423997c94f7ff004407567887e9cdd855c553b7..f0524cd70e9b687baebf79cecfeef677a4a59e0c 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -36,6 +36,7 @@ enum cpuhp_state {
        CPUHP_AP_PERF_XTENSA_STARTING,
        CPUHP_AP_ARM_VFP_STARTING,
        CPUHP_AP_PERF_ARM_STARTING,
+       CPUHP_AP_ARM_ARCH_TIMER_STARTING,
        CPUHP_AP_KVM_STARTING,
        CPUHP_AP_NOTIFY_STARTING,
        CPUHP_AP_ONLINE,