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Subject[tip:smp/hotplug] leds/trigger/cpu: Convert to hotplug state machine
Commit-ID:  911a359de96d5e9d24f50c74a48c6f3cf061539a
Gitweb: http://git.kernel.org/tip/911a359de96d5e9d24f50c74a48c6f3cf061539a
Author: Richard Cochran <rcochran@linutronix.de>
AuthorDate: Wed, 13 Jul 2016 17:16:45 +0000
Committer: Ingo Molnar <mingo@kernel.org>
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@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-leds@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153336.465496902@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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,
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