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Subject[tip:smp/hotplug] clocksource/qcom-timer: Convert to hotplug state machine
Commit-ID:  b04041655d0cf84b77802cb0b4517e672df04f01
Gitweb: http://git.kernel.org/tip/b04041655d0cf84b77802cb0b4517e672df04f01
Author: Richard Cochran <rcochran@linutronix.de>
AuthorDate: Wed, 13 Jul 2016 17:16:43 +0000
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 15 Jul 2016 10:40:25 +0200

clocksource/qcom-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/20160713153336.295486558@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
drivers/clocksource/qcom-timer.c | 41 +++++++++++-----------------------------
include/linux/cpuhotplug.h | 1 +
2 files changed, 12 insertions(+), 30 deletions(-)

diff --git a/drivers/clocksource/qcom-timer.c b/drivers/clocksource/qcom-timer.c
index 6625763..3283cfa 100644
--- a/drivers/clocksource/qcom-timer.c
+++ b/drivers/clocksource/qcom-timer.c
@@ -105,9 +105,9 @@ static struct clocksource msm_clocksource = {
static int msm_timer_irq;
static int msm_timer_has_ppi;

-static int msm_local_timer_setup(struct clock_event_device *evt)
+static int msm_local_timer_starting_cpu(unsigned int cpu)
{
- int cpu = smp_processor_id();
+ struct clock_event_device *evt = per_cpu_ptr(msm_evt, cpu);
int err;

evt->irq = msm_timer_irq;
@@ -135,35 +135,15 @@ static int msm_local_timer_setup(struct clock_event_device *evt)
return 0;
}

-static void msm_local_timer_stop(struct clock_event_device *evt)
+static int msm_local_timer_dying_cpu(unsigned int cpu)
{
+ struct clock_event_device *evt = per_cpu_ptr(msm_evt, cpu);
+
evt->set_state_shutdown(evt);
disable_percpu_irq(evt->irq);
+ return 0;
}

-static int msm_timer_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
-{
- /*
- * Grab cpu pointer in each case to avoid spurious
- * preemptible warnings
- */
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_STARTING:
- msm_local_timer_setup(this_cpu_ptr(msm_evt));
- break;
- case CPU_DYING:
- msm_local_timer_stop(this_cpu_ptr(msm_evt));
- break;
- }
-
- return NOTIFY_OK;
-}
-
-static struct notifier_block msm_timer_cpu_nb = {
- .notifier_call = msm_timer_cpu_notify,
-};
-
static u64 notrace msm_sched_clock_read(void)
{
return msm_clocksource.read(&msm_clocksource);
@@ -200,14 +180,15 @@ static int __init msm_timer_init(u32 dgt_hz, int sched_bits, int irq,
if (res) {
pr_err("request_percpu_irq failed\n");
} else {
- res = register_cpu_notifier(&msm_timer_cpu_nb);
+ /* Install and invoke hotplug callbacks */
+ res = cpuhp_setup_state(CPUHP_AP_QCOM_TIMER_STARTING,
+ "AP_QCOM_TIMER_STARTING",
+ msm_local_timer_starting_cpu,
+ msm_local_timer_dying_cpu);
if (res) {
free_percpu_irq(irq, msm_evt);
goto err;
}
-
- /* Immediately configure the timer on the boot CPU */
- msm_local_timer_setup(raw_cpu_ptr(msm_evt));
}

err:
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index afba3b1..d74d15a 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -39,6 +39,7 @@ enum cpuhp_state {
CPUHP_AP_ARM_ARCH_TIMER_STARTING,
CPUHP_AP_DUMMY_TIMER_STARTING,
CPUHP_AP_METAG_TIMER_STARTING,
+ CPUHP_AP_QCOM_TIMER_STARTING,
CPUHP_AP_KVM_STARTING,
CPUHP_AP_NOTIFY_STARTING,
CPUHP_AP_ONLINE,
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