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>

2 files changed, 16 insertions, 17 deletions

diff --git a/drivers/leds/trigger/ledtrig-cpu.c b/drivers/leds/trigger/ledtrig-cpu.c
index 938467fb82be..4a6a182d0a88 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 456e3d93272c..24f56e290003 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,