irqchip/gic: Convert to hotplug state machine

More or less straightforward, although this driver sports some very
interesting SMP setup code. Regarding the callback ordering, this
deleted comment is interesting:

   ... the GIC needs to be up before the ARM generic timers.

That comment is half baken as the same requirement is true for perf.

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: Jason Cooper <jason@lakedaemon.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153333.069777215@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 7 insertions, 17 deletions

diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index fbc4ae2afd29..606f114166a1 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -984,25 +984,12 @@ static int gic_irq_domain_translate(struct irq_domain *d,
         return -EINVAL;
 }
 
-#ifdef CONFIG_SMP
-static int gic_secondary_init(struct notifier_block *nfb, unsigned long action,
-                              void *hcpu)
+static int gic_starting_cpu(unsigned int cpu)
 {
-        if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
-                gic_cpu_init(&gic_data[0]);
-        return NOTIFY_OK;
+        gic_cpu_init(&gic_data[0]);
+        return 0;
 }
 
-/*
- * Notifier for enabling the GIC CPU interface. Set an arbitrarily high
- * priority because the GIC needs to be up before the ARM generic timers.
- */
-static struct notifier_block gic_cpu_notifier = {
-        .notifier_call = gic_secondary_init,
-        .priority = 100,
-};
-#endif
-
 static int gic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
                                 unsigned int nr_irqs, void *arg)
 {
@@ -1148,8 +1135,10 @@ static int __init __gic_init_bases(struct gic_chip_data *gic, int irq_start,
                         gic_cpu_map[i] = 0xff;
 #ifdef CONFIG_SMP
                 set_smp_cross_call(gic_raise_softirq);
-                register_cpu_notifier(&gic_cpu_notifier);
 #endif
+                cpuhp_setup_state_nocalls(CPUHP_AP_IRQ_GIC_STARTING,
+                                          "AP_IRQ_GIC_STARTING",
+                                          gic_starting_cpu, NULL);
                 set_handle_irq(gic_handle_irq);
                 if (static_key_true(&supports_deactivate))
                         pr_info("GIC: Using split EOI/Deactivate mode\n");
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index fe056408335e..edc8adf26410 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -9,6 +9,7 @@ enum cpuhp_state {
         CPUHP_AP_IDLE_DEAD,
         CPUHP_AP_OFFLINE,
         CPUHP_AP_SCHED_STARTING,
+        CPUHP_AP_IRQ_GIC_STARTING,
         CPUHP_AP_NOTIFY_STARTING,
         CPUHP_AP_ONLINE,
         CPUHP_TEARDOWN_CPU,