[PATCH] acpi: intel_idle : break dependency between modules

[Daniel Lezcano <daniel.lezcano@linaro.org>]

When the system is booted with some cpus offline, the idle
driver is not initialized. When a cpu is set online, the
acpi code call the intel idle init function. Unfortunately
this code introduce a dependency between intel_idle and acpi.

This patch is intended to remove this dependency by using the
notifier of intel_idle. In order to make it work, the notifier
must be initialized in the right order, acpi then intel_idle.
This is done in the Makefile. This patch has the benefit of
encapsulating the intel_idle driver and remove some exported
functions.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/Makefile                |    3 ++-
 drivers/acpi/processor_driver.c |    7 -------
 drivers/idle/intel_idle.c       |   22 ++++++++++++++--------
 include/linux/cpuidle.h         |    7 -------
 4 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/drivers/Makefile b/drivers/Makefile
index 2ba29ff..a2454b8 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -12,8 +12,9 @@ obj-$(CONFIG_PCI)		+= pci/
 obj-$(CONFIG_PARISC)		+= parisc/
 obj-$(CONFIG_RAPIDIO)		+= rapidio/
 obj-y				+= video/
-obj-y				+= idle/
+# acpi must come before idle for initialization
 obj-$(CONFIG_ACPI)		+= acpi/
+obj-y				+= idle/
 obj-$(CONFIG_SFI)		+= sfi/
 # PnP must come after ACPI since it will eventually need to check if acpi
 # was used and do nothing if so
diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 0734086..8648b29 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -427,18 +427,11 @@ static int acpi_cpu_soft_notify(struct notifier_block *nfb,
 		 * Initialize missing things
 		 */
 		if (pr->flags.need_hotplug_init) {
-			struct cpuidle_driver *idle_driver =
-				cpuidle_get_driver();
-
 			printk(KERN_INFO "Will online and init hotplugged "
 			       "CPU: %d\n", pr->id);
 			WARN(acpi_processor_start(pr), "Failed to start CPU:"
 				" %d\n", pr->id);
 			pr->flags.need_hotplug_init = 0;
-			if (idle_driver && !strcmp(idle_driver->name,
-						   "intel_idle")) {
-				intel_idle_cpu_init(pr->id);
-			}
 		/* Normal CPU soft online event */
 		} else {
 			acpi_processor_ppc_has_changed(pr, 0);
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index d0f59c3..4c36039 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -96,6 +96,7 @@ static const struct idle_cpu *icpu;
 static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
 static int intel_idle(struct cpuidle_device *dev,
 			struct cpuidle_driver *drv, int index);
+static int intel_idle_cpu_init(int cpu);
 
 static struct cpuidle_state *cpuidle_state_table;
 
@@ -302,22 +303,28 @@ static void __setup_broadcast_timer(void *arg)
 	clockevents_notify(reason, &cpu);
 }
 
-static int setup_broadcast_cpuhp_notify(struct notifier_block *n,
-		unsigned long action, void *hcpu)
+static int cpu_hotplug_notify(struct notifier_block *n,
+			      unsigned long action, void *hcpu)
 {
 	int hotcpu = (unsigned long)hcpu;
+	struct cpuidle_device *dev;
 
 	switch (action & 0xf) {
 	case CPU_ONLINE:
 		smp_call_function_single(hotcpu, __setup_broadcast_timer,
 			(void *)true, 1);
+
+		dev = per_cpu_ptr(intel_idle_cpuidle_devices, hotcpu);
+		if (!dev->registered)
+			intel_idle_cpu_init(hotcpu);
+
 		break;
 	}
 	return NOTIFY_OK;
 }
 
-static struct notifier_block setup_broadcast_notifier = {
-	.notifier_call = setup_broadcast_cpuhp_notify,
+static struct notifier_block cpu_hotplug_notifier = {
+	.notifier_call = cpu_hotplug_notify,
 };
 
 static void auto_demotion_disable(void *dummy)
@@ -407,7 +414,7 @@ static int intel_idle_probe(void)
 		lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
 	else {
 		on_each_cpu(__setup_broadcast_timer, (void *)true, 1);
-		register_cpu_notifier(&setup_broadcast_notifier);
+		register_cpu_notifier(&cpu_hotplug_notifier);
 	}
 
 	pr_debug(PREFIX "v" INTEL_IDLE_VERSION
@@ -494,7 +501,7 @@ static int intel_idle_cpuidle_driver_init(void)
  * allocate, initialize, register cpuidle_devices
  * @cpu: cpu/core to initialize
  */
-int intel_idle_cpu_init(int cpu)
+static int intel_idle_cpu_init(int cpu)
 {
 	int cstate;
 	struct cpuidle_device *dev;
@@ -539,7 +546,6 @@ int intel_idle_cpu_init(int cpu)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(intel_idle_cpu_init);
 
 static int __init intel_idle_init(void)
 {
@@ -583,7 +589,7 @@ static void __exit intel_idle_exit(void)
 
 	if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) {
 		on_each_cpu(__setup_broadcast_timer, (void *)false, 1);
-		unregister_cpu_notifier(&setup_broadcast_notifier);
+		unregister_cpu_notifier(&cpu_hotplug_notifier);
 	}
 
 	return;
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 5ab7183..66d7e0d 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -213,14 +213,7 @@ struct cpuidle_governor {
 extern int cpuidle_register_governor(struct cpuidle_governor *gov);
 extern void cpuidle_unregister_governor(struct cpuidle_governor *gov);
 
-#ifdef CONFIG_INTEL_IDLE
-extern int intel_idle_cpu_init(int cpu);
 #else
-static inline int intel_idle_cpu_init(int cpu) { return -1; }
-#endif
-
-#else
-static inline int intel_idle_cpu_init(int cpu) { return -1; }
 
 static inline int cpuidle_register_governor(struct cpuidle_governor *gov)
 {return 0;}
-- 
1.7.5.4