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Subject[patch V2 62/67] [PATCH] clocksource: arm_global_timer: Convert to hotplug state machine.
From: Richard Cochran <rcochran@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Srinivas Kandagatla <srinivas.kandagatla@gmail.com>
Cc: Maxime Coquelin <maxime.coquelin@st.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: kernel@stlinux.com
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
drivers/clocksource/arm_global_timer.c | 39 ++++++++-------------------------
include/linux/cpuhotplug.h | 1
2 files changed, 11 insertions(+), 29 deletions(-)

--- a/drivers/clocksource/arm_global_timer.c
+++ b/drivers/clocksource/arm_global_timer.c
@@ -165,9 +165,9 @@ static irqreturn_t gt_clockevent_interru
return IRQ_HANDLED;
}

-static int gt_clockevents_init(struct clock_event_device *clk)
+static int gt_starting_cpu(unsigned int cpu)
{
- int cpu = smp_processor_id();
+ struct clock_event_device *clk = this_cpu_ptr(gt_evt);

clk->name = "arm_global_timer";
clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
@@ -186,10 +186,13 @@ static int gt_clockevents_init(struct cl
return 0;
}

-static void gt_clockevents_stop(struct clock_event_device *clk)
+static int gt_dying_cpu(unsigned int cpu)
{
+ struct clock_event_device *clk = this_cpu_ptr(gt_evt);
+
gt_clockevent_shutdown(clk);
disable_percpu_irq(clk->irq);
+ return 0;
}

static cycle_t gt_clocksource_read(struct clocksource *cs)
@@ -252,24 +255,6 @@ static int __init gt_clocksource_init(vo
return clocksource_register_hz(&gt_clocksource, gt_clk_rate);
}

-static int gt_cpu_notify(struct notifier_block *self, unsigned long action,
- void *hcpu)
-{
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_STARTING:
- gt_clockevents_init(this_cpu_ptr(gt_evt));
- break;
- case CPU_DYING:
- gt_clockevents_stop(this_cpu_ptr(gt_evt));
- break;
- }
-
- return NOTIFY_OK;
-}
-static struct notifier_block gt_cpu_nb = {
- .notifier_call = gt_cpu_notify,
-};
-
static int __init global_timer_of_register(struct device_node *np)
{
struct clk *gt_clk;
@@ -325,18 +310,14 @@ static int __init global_timer_of_regist
goto out_free;
}

- err = register_cpu_notifier(&gt_cpu_nb);
- if (err) {
- pr_warn("global-timer: unable to register cpu notifier.\n");
- goto out_irq;
- }
-
- /* Immediately configure the timer on the boot CPU */
+ /* Register and immediately configure the timer on the boot CPU */
err = gt_clocksource_init();
if (err)
goto out_irq;

- err = gt_clockevents_init(this_cpu_ptr(gt_evt));
+ err = cpuhp_setup_state(CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
+ "AP_ARM_GLOBAL_TIMER_STARTING",
+ gt_starting_cpu, gt_dying_cpu);
if (err)
goto out_irq;

--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -48,6 +48,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_ARM_STARTING,
CPUHP_AP_ARM_L2X0_STARTING,
CPUHP_AP_ARM_ARCH_TIMER_STARTING,
+ CPUHP_AP_ARM_GLOBAL_TIMER_STARTING,
CPUHP_AP_DUMMY_TIMER_STARTING,
CPUHP_AP_ARM_TWD_STARTING,
CPUHP_AP_METAG_TIMER_STARTING,

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