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 <[email protected]> Reviewed-by: Sebastian Andrzej Siewior <[email protected]> Cc: Jason Cooper <[email protected]> Cc: Marc Zyngier <[email protected]> Signed-off-by: Anna-Maria Gleixner <[email protected]> --- drivers/irqchip/irq-gic.c | 23 ++++++----------------- include/linux/cpuhotplug.h | 1 + 2 files changed, 7 insertions(+), 17 deletions(-) --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -984,25 +984,12 @@ static int gic_irq_domain_translate(stru 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(struc 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"); --- 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,
