ACPI: intel_idle : break dependency between modules

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. 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>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

3 files changed, 27 insertions, 28 deletions

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 0734086537b8..8648b29f6eec 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 d0f59c3f87ef..fe95d5464a02 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 +303,35 @@ 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);
+
+                if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
+                        smp_call_function_single(hotcpu, __setup_broadcast_timer,
+                                                 (void *)true, 1);
+
+                /*
+                 * Some systems can hotplug a cpu at runtime after
+                 * the kernel has booted, we have to initialize the
+                 * driver in this case
+                 */
+                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)
@@ -405,10 +419,10 @@ static int intel_idle_probe(void)
 
         if (boot_cpu_has(X86_FEATURE_ARAT))     /* Always Reliable APIC Timer */
                 lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
-        else {
+        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
                 " model 0x%X\n", boot_cpu_data.x86_model);
@@ -494,7 +508,7 @@ 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 +553,6 @@ int intel_idle_cpu_init(int cpu)
 
         return 0;
 }
-EXPORT_SYMBOL_GPL(intel_idle_cpu_init);
 
 static int __init intel_idle_init(void)
 {
@@ -581,10 +594,10 @@ static void __exit intel_idle_exit(void)
         intel_idle_cpuidle_devices_uninit();
         cpuidle_unregister_driver(&intel_idle_driver);
 
-        if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) {
+
+        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 27cfced7b57b..524bb6f3b6c4 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -206,14 +206,7 @@ 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;}