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Subject[patch V2 38/67] clocksource/arm_arch_timer: Convert to hotplug state machine
From: Richard Cochran <rcochran@linutronix.de>

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>
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>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
drivers/clocksource/arm_arch_timer.c | 54 +++++++++++++++++-------------------
include/linux/cpuhotplug.h | 1 +
2 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5effd30..28bce3f 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],
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 1d71f38..672f690 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -37,6 +37,7 @@ 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,
--
2.8.1


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