linux-kernel - [tip:smp/hotplug] clocksource/armada-370-xp: Convert to hotplug state machine

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Date:	Tue, 19 Jul 2016 00:31:39 -0700
From:	tip-bot for Richard Cochran <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, peterz@...radead.org, daniel.lezcano@...aro.org,
	rcochran@...utronix.de, torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org, anna-maria@...utronix.de,
	hpa@...or.com, bigeasy@...utronix.de, tglx@...utronix.de
Subject: [tip:smp/hotplug] clocksource/armada-370-xp: Convert to hotplug
 state machine

Commit-ID:  2c48fef74ca42d05c3efd4345b8a068ebf479a5f
Gitweb:     http://git.kernel.org/tip/2c48fef74ca42d05c3efd4345b8a068ebf479a5f
Author:     Richard Cochran <rcochran@...utronix.de>
AuthorDate: Wed, 13 Jul 2016 17:17:06 +0000
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 15 Jul 2016 10:41:45 +0200

clocksource/armada-370-xp: 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@...utronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: rt@...utronix.de
Link: http://lkml.kernel.org/r/20160713153338.229913786@linutronix.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 drivers/clocksource/time-armada-370-xp.c | 41 +++++++++-----------------------
 include/linux/cpuhotplug.h               |  1 +
 2 files changed, 12 insertions(+), 30 deletions(-)

diff --git a/drivers/clocksource/time-armada-370-xp.c b/drivers/clocksource/time-armada-370-xp.c
index 20ec066..719b478 100644
--- a/drivers/clocksource/time-armada-370-xp.c
+++ b/drivers/clocksource/time-armada-370-xp.c
@@ -170,10 +170,10 @@ static irqreturn_t armada_370_xp_timer_interrupt(int irq, void *dev_id)
 /*
  * Setup the local clock events for a CPU.
  */
-static int armada_370_xp_timer_setup(struct clock_event_device *evt)
+static int armada_370_xp_timer_starting_cpu(unsigned int cpu)
 {
+	struct clock_event_device *evt = per_cpu_ptr(armada_370_xp_evt, cpu);
 	u32 clr = 0, set = 0;
-	int cpu = smp_processor_id();
 
 	if (timer25Mhz)
 		set = TIMER0_25MHZ;
@@ -200,35 +200,15 @@ static int armada_370_xp_timer_setup(struct clock_event_device *evt)
 	return 0;
 }
 
-static void armada_370_xp_timer_stop(struct clock_event_device *evt)
+static int armada_370_xp_timer_dying_cpu(unsigned int cpu)
 {
+	struct clock_event_device *evt = per_cpu_ptr(armada_370_xp_evt, cpu);
+
 	evt->set_state_shutdown(evt);
 	disable_percpu_irq(evt->irq);
+	return 0;
 }
 
-static int armada_370_xp_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:
-		armada_370_xp_timer_setup(this_cpu_ptr(armada_370_xp_evt));
-		break;
-	case CPU_DYING:
-		armada_370_xp_timer_stop(this_cpu_ptr(armada_370_xp_evt));
-		break;
-	}
-
-	return NOTIFY_OK;
-}
-
-static struct notifier_block armada_370_xp_timer_cpu_nb = {
-	.notifier_call = armada_370_xp_timer_cpu_notify,
-};
-
 static u32 timer0_ctrl_reg, timer0_local_ctrl_reg;
 
 static int armada_370_xp_timer_suspend(void)
@@ -322,8 +302,6 @@ static int __init armada_370_xp_timer_common_init(struct device_node *np)
 		return res;
 	}
 
-	register_cpu_notifier(&armada_370_xp_timer_cpu_nb);
-
 	armada_370_xp_evt = alloc_percpu(struct clock_event_device);
 	if (!armada_370_xp_evt)
 		return -ENOMEM;
@@ -341,9 +319,12 @@ static int __init armada_370_xp_timer_common_init(struct device_node *np)
 		return res;
 	}
 
-	res = armada_370_xp_timer_setup(this_cpu_ptr(armada_370_xp_evt));
+	res = cpuhp_setup_state(CPUHP_AP_ARMADA_TIMER_STARTING,
+				"AP_ARMADA_TIMER_STARTING",
+				armada_370_xp_timer_starting_cpu,
+				armada_370_xp_timer_dying_cpu);
 	if (res) {
-		pr_err("Failed to setup timer");
+		pr_err("Failed to setup hotplug state and timer");
 		return res;
 	}
 
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 7ad8a7e7..ee7f750 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -53,6 +53,7 @@ enum cpuhp_state {
 	CPUHP_AP_ARM_TWD_STARTING,
 	CPUHP_AP_METAG_TIMER_STARTING,
 	CPUHP_AP_QCOM_TIMER_STARTING,
+	CPUHP_AP_ARMADA_TIMER_STARTING,
 	CPUHP_AP_MIPS_GIC_TIMER_STARTING,
 	CPUHP_AP_KVM_STARTING,
 	CPUHP_AP_KVM_ARM_VGIC_INIT_STARTING,