[PATCH][V2] cpuidle : use percpu cpuidle in the core code

[Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>]

The usual cpuidle initialization routines are to register the
driver, then register a cpuidle device per cpu.

With the device's state count default initialization with the
driver's state count, the code initialization remains mostly the
same in the different drivers.

We can then add a new function 'cpuidle_register' where we register
the driver and the devices. These devices can be defined in a global
static variable in cpuidle.c. We will be able to factor out and
remove a lot of duplicate lines of code.

As we still have some drivers, with different initialization routines,
we keep 'cpuidle_register_driver' and 'cpuidle_register_device' as low
level initialization routines to do some specific operations on the
cpuidle devices.

Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
---
 drivers/cpuidle/cpuidle.c |   42 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/cpuidle.h   |    3 +++
 2 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 87411ce..151c55a 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -23,6 +23,7 @@
 #include "cpuidle.h"
 
 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
+DEFINE_PER_CPU(struct cpuidle_device, cpuidle_device);
 
 DEFINE_MUTEX(cpuidle_lock);
 LIST_HEAD(cpuidle_detected_devices);
@@ -419,6 +420,47 @@ int cpuidle_register_device(struct cpuidle_device *dev)
 
 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 
+/*
+ * cpuidle_register : register cpuidle driver and devices
+ * Note this function must be called after smp_init.
+ * @drv : the cpuidle driver
+ * Returns 0 on success, < 0 otherwise
+ */
+int cpuidle_register(struct cpuidle_driver *drv)
+{
+	int ret, cpu, i;
+	struct cpuidle_device *dev;
+
+	ret = cpuidle_register_driver(drv);
+	if (ret)
+		return ret;
+
+	for_each_online_cpu(cpu) {
+		dev = &per_cpu(cpuidle_device, cpu);
+		dev->cpu = cpu;
+
+		ret = cpuidle_register_device(dev);
+		if (ret)
+			goto out_unregister;
+	}
+
+out:
+	return ret;
+
+out_unregister:
+	for_each_online_cpu(i) {
+		if (i == cpu)
+			break;
+		dev = &per_cpu(cpuidle_device, cpu);
+		cpuidle_unregister_device(dev);
+	}
+
+	cpuidle_unregister_driver(drv);
+
+	goto out;
+}
+EXPORT_SYMBOL_GPL(cpuidle_register);
+
 /**
  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
  * @dev: the cpu
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 6c26a3d..3475294 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -135,6 +135,7 @@ struct cpuidle_driver {
 #ifdef CONFIG_CPU_IDLE
 extern void disable_cpuidle(void);
 extern int cpuidle_idle_call(void);
+extern int cpuidle_register(struct cpuidle_driver *drv);
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 struct cpuidle_driver *cpuidle_get_driver(void);
 extern void cpuidle_unregister_driver(struct cpuidle_driver *drv);
@@ -154,6 +155,8 @@ extern int cpuidle_play_dead(void);
 #else
 static inline void disable_cpuidle(void) { }
 static inline int cpuidle_idle_call(void) { return -ENODEV; }
+static inline int cpuidle_register(struct cpuidle_driver *drv)
+{return -ENODEV; }
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }
 static inline struct cpuidle_driver *cpuidle_get_driver(void) {return NULL; }
-- 
1.7.5.4

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