clocksource: mips-gic: Use CPU notifiers to setup the timer

Instead of requiring an explicit call to gic_clockevent_init in the SMP
startup path, use CPU notifiers to register and enable the GIC timer on
CPU startup.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8139/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 44 insertions, 16 deletions

diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c
index 05bdfe1e3e03..3ce992bc574f 100644
--- a/drivers/clocksource/mips-gic-timer.c
+++ b/drivers/clocksource/mips-gic-timer.c
@@ -6,9 +6,11 @@
  * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
  */
 #include <linux/clockchips.h>
+#include <linux/cpu.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/irqchip/mips-gic.h>
+#include <linux/notifier.h>
 #include <linux/percpu.h>
 #include <linux/smp.h>
 #include <linux/time.h>
@@ -16,7 +18,7 @@
 #include <asm/time.h>
 
 static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
-static int gic_timer_irq_installed;
+static int gic_timer_irq;
 static unsigned int gic_frequency;
 
 static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
@@ -53,18 +55,9 @@ struct irqaction gic_compare_irqaction = {
         .name = "timer",
 };
 
-int gic_clockevent_init(void)
+static void gic_clockevent_cpu_init(struct clock_event_device *cd)
 {
         unsigned int cpu = smp_processor_id();
-        struct clock_event_device *cd;
-        unsigned int irq;
-
-        if (!cpu_has_counter || !gic_frequency)
-                return -ENXIO;
-
-        irq = MIPS_GIC_IRQ_BASE + GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
-
-        cd = &per_cpu(gic_clockevent_device, cpu);
 
         cd->name                = "MIPS GIC";
         cd->features            = CLOCK_EVT_FEAT_ONESHOT |
@@ -77,19 +70,52 @@ int gic_clockevent_init(void)
         cd->min_delta_ns        = clockevent_delta2ns(0x300, cd);
 
         cd->rating              = 300;
-        cd->irq                 = irq;
+        cd->irq                 = gic_timer_irq;
         cd->cpumask             = cpumask_of(cpu);
         cd->set_next_event      = gic_next_event;
         cd->set_mode            = gic_set_clock_mode;
 
         clockevents_register_device(cd);
 
-        if (!gic_timer_irq_installed) {
-                setup_percpu_irq(irq, &gic_compare_irqaction);
-                gic_timer_irq_installed = 1;
+        enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
+}
+
+static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
+{
+        disable_percpu_irq(gic_timer_irq);
+}
+
+static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action,
+                                void *data)
+{
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_STARTING:
+                gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
+                break;
+        case CPU_DYING:
+                gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
+                break;
         }
 
-        enable_percpu_irq(irq, IRQ_TYPE_NONE);
+        return NOTIFY_OK;
+}
+
+static struct notifier_block gic_cpu_nb = {
+        .notifier_call = gic_cpu_notifier,
+};
+
+static int gic_clockevent_init(void)
+{
+        if (!cpu_has_counter || !gic_frequency)
+                return -ENXIO;
+
+        gic_timer_irq = MIPS_GIC_IRQ_BASE +
+                GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE);
+        setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
+
+        register_cpu_notifier(&gic_cpu_nb);
+
+        gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device));
 
         return 0;
 }
@@ -116,4 +142,6 @@ void __init gic_clocksource_init(unsigned int frequency)
         gic_clocksource.rating = 200 + frequency / 10000000;
 
         clocksource_register_hz(&gic_clocksource, frequency);
+
+        gic_clockevent_init();
 }