[tip:smp/hotplug] leds/trigger/cpu: Convert to hotplug state machine

[tip-bot for Richard Cochran]

Commit-ID:  911a359de96d5e9d24f50c74a48c6f3cf061539a
Gitweb:     http://git.kernel.org/tip/911a359de96d5e9d24f50c74a48c6f3cf061539a
Author:     Richard Cochran <rcochran@xxxxxxxxxxxxx>
AuthorDate: Wed, 13 Jul 2016 17:16:45 +0000
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 15 Jul 2016 10:40:26 +0200

leds/trigger/cpu: Convert to hotplug state machine

This is a straightforward conversion. We place this callback last
in the list so that the LED illuminates only after a successful
bring up sequence.

( NOTE: The patch adds a FIXME question about the callback used,
        this question should probably be revisited later on.)

Signed-off-by: Richard Cochran <rcochran@xxxxxxxxxxxxx>
Signed-off-by: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Acked-by: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Richard Purdie <rpurdie@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-leds@xxxxxxxxxxxxxxx
Cc: rt@xxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20160713153336.465496902@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 drivers/leds/trigger/ledtrig-cpu.c | 32 +++++++++++++++-----------------
 include/linux/cpuhotplug.h         |  1 +
 2 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/drivers/leds/trigger/ledtrig-cpu.c b/drivers/leds/trigger/ledtrig-cpu.c
index 938467f..4a6a182 100644
--- a/drivers/leds/trigger/ledtrig-cpu.c
+++ b/drivers/leds/trigger/ledtrig-cpu.c
@@ -92,25 +92,17 @@ static struct syscore_ops ledtrig_cpu_syscore_ops = {
 	.resume		= ledtrig_cpu_syscore_resume,
 };
 
-static int ledtrig_cpu_notify(struct notifier_block *self,
-					   unsigned long action, void *hcpu)
+static int ledtrig_starting_cpu(unsigned int cpu)
 {
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_STARTING:
-		ledtrig_cpu(CPU_LED_START);
-		break;
-	case CPU_DYING:
-		ledtrig_cpu(CPU_LED_STOP);
-		break;
-	}
-
-	return NOTIFY_OK;
+	ledtrig_cpu(CPU_LED_START);
+	return 0;
 }
 
-
-static struct notifier_block ledtrig_cpu_nb = {
-	.notifier_call = ledtrig_cpu_notify,
-};
+static int ledtrig_dying_cpu(unsigned int cpu)
+{
+	ledtrig_cpu(CPU_LED_STOP);
+	return 0;
+}
 
 static int __init ledtrig_cpu_init(void)
 {
@@ -133,7 +125,13 @@ static int __init ledtrig_cpu_init(void)
 	}
 
 	register_syscore_ops(&ledtrig_cpu_syscore_ops);
-	register_cpu_notifier(&ledtrig_cpu_nb);
+
+	/*
+	 * FIXME: Why needs this to happen in the interrupt disabled
+	 * low level bringup phase of a cpu?
+	 */
+	cpuhp_setup_state(CPUHP_AP_LEDTRIG_STARTING, "AP_LEDTRIG_STARTING",
+			  ledtrig_starting_cpu, ledtrig_dying_cpu);
 
 	pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
 
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 456e3d9..24f56e2 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -42,6 +42,7 @@ enum cpuhp_state {
 	CPUHP_AP_QCOM_TIMER_STARTING,
 	CPUHP_AP_MIPS_GIC_TIMER_STARTING,
 	CPUHP_AP_KVM_STARTING,
+	CPUHP_AP_LEDTRIG_STARTING,
 	CPUHP_AP_NOTIFY_STARTING,
 	CPUHP_AP_ONLINE,
 	CPUHP_TEARDOWN_CPU,