cpuidle: Single/Global registration of idle states

This patch makes the cpuidle_states structure global (single copy)
instead of per-cpu. The statistics needed on per-cpu basis
by the governor are kept per-cpu. This simplifies the cpuidle
subsystem as state registration is done by single cpu only.
Having single copy of cpuidle_states saves memory. Rare case
of asymmetric C-states can be handled within the cpuidle driver
and architectures such as POWER do not have asymmetric C-states.

Having single/global registration of all the idle states,
dynamic C-state transitions on x86 are handled by
the boot cpu. Here, the boot cpu  would disable all the devices,
re-populate the states and later enable all the devices,
irrespective of the cpu that would receive the notification first.

Reference:
https://lkml.org/lkml/2011/4/25/83

Signed-off-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: Trinabh Gupta <g.trinabh@gmail.com>
Tested-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 0156540b3f79..c90418822f40 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -22,6 +22,7 @@
 #define CPUIDLE_DESC_LEN        32
 
 struct cpuidle_device;
+struct cpuidle_driver;
 
 
 /****************************
@@ -45,6 +46,7 @@ struct cpuidle_state {
         unsigned int    target_residency; /* in US */
 
         int (*enter)    (struct cpuidle_device *dev,
+                        struct cpuidle_driver *drv,
                         int index);
 };
 
@@ -83,12 +85,10 @@ struct cpuidle_state_kobj {
 struct cpuidle_device {
         unsigned int            registered:1;
         unsigned int            enabled:1;
-        unsigned int            power_specified:1;
         unsigned int            cpu;
 
         int                     last_residency;
         int                     state_count;
-        struct cpuidle_state    states[CPUIDLE_STATE_MAX];
         struct cpuidle_state_usage      states_usage[CPUIDLE_STATE_MAX];
         struct cpuidle_state_kobj *kobjs[CPUIDLE_STATE_MAX];
 
@@ -96,7 +96,6 @@ struct cpuidle_device {
         struct kobject          kobj;
         struct completion       kobj_unregister;
         void                    *governor_data;
-        int                     safe_state_index;
 };
 
 DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
@@ -120,6 +119,11 @@ static inline int cpuidle_get_last_residency(struct cpuidle_device *dev)
 struct cpuidle_driver {
         char                    name[CPUIDLE_NAME_LEN];
         struct module           *owner;
+
+        unsigned int            power_specified:1;
+        struct cpuidle_state    states[CPUIDLE_STATE_MAX];
+        int                     state_count;
+        int                     safe_state_index;
 };
 
 #ifdef CONFIG_CPU_IDLE
@@ -166,10 +170,13 @@ struct cpuidle_governor {
         struct list_head        governor_list;
         unsigned int            rating;
 
-        int  (*enable)          (struct cpuidle_device *dev);
-        void (*disable)         (struct cpuidle_device *dev);
+        int  (*enable)          (struct cpuidle_driver *drv,
+                                        struct cpuidle_device *dev);
+        void (*disable)         (struct cpuidle_driver *drv,
+                                        struct cpuidle_device *dev);
 
-        int  (*select)          (struct cpuidle_device *dev);
+        int  (*select)          (struct cpuidle_driver *drv,
+                                        struct cpuidle_device *dev);
         void (*reflect)         (struct cpuidle_device *dev, int index);
 
         struct module           *owner;