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, 11 insertions, 7 deletions

diff --git a/arch/sh/kernel/cpu/shmobile/cpuidle.c b/arch/sh/kernel/cpu/shmobile/cpuidle.c
index 7be50d4c4268..ad1012ad6b42 100644
--- a/arch/sh/kernel/cpu/shmobile/cpuidle.c
+++ b/arch/sh/kernel/cpu/shmobile/cpuidle.c
@@ -25,6 +25,7 @@ static unsigned long cpuidle_mode[] = {
 };
 
 static int cpuidle_sleep_enter(struct cpuidle_device *dev,
+                                struct cpuidle_driver *drv,
                                 int index)
 {
         unsigned long allowed_mode = arch_hwblk_sleep_mode();
@@ -64,19 +65,19 @@ static struct cpuidle_driver cpuidle_driver = {
 void sh_mobile_setup_cpuidle(void)
 {
         struct cpuidle_device *dev = &cpuidle_dev;
+        struct cpuidle_driver *drv = &cpuidle_driver;
         struct cpuidle_state *state;
         int i;
 
-        cpuidle_register_driver(&cpuidle_driver);
 
         for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
-                dev->states[i].name[0] = '\0';
-                dev->states[i].desc[0] = '\0';
+                drv->states[i].name[0] = '\0';
+                drv->states[i].desc[0] = '\0';
         }
 
         i = CPUIDLE_DRIVER_STATE_START;
 
-        state = &dev->states[i++];
+        state = &drv->states[i++];
         snprintf(state->name, CPUIDLE_NAME_LEN, "C1");
         strncpy(state->desc, "SuperH Sleep Mode", CPUIDLE_DESC_LEN);
         state->exit_latency = 1;
@@ -86,10 +87,10 @@ void sh_mobile_setup_cpuidle(void)
         state->flags |= CPUIDLE_FLAG_TIME_VALID;
         state->enter = cpuidle_sleep_enter;
 
-        dev->safe_state_index = i-1;
+        drv->safe_state_index = i-1;
 
         if (sh_mobile_sleep_supported & SUSP_SH_SF) {
-                state = &dev->states[i++];
+                state = &drv->states[i++];
                 snprintf(state->name, CPUIDLE_NAME_LEN, "C2");
                 strncpy(state->desc, "SuperH Sleep Mode [SF]",
                         CPUIDLE_DESC_LEN);
@@ -102,7 +103,7 @@ void sh_mobile_setup_cpuidle(void)
         }
 
         if (sh_mobile_sleep_supported & SUSP_SH_STANDBY) {
-                state = &dev->states[i++];
+                state = &drv->states[i++];
                 snprintf(state->name, CPUIDLE_NAME_LEN, "C3");
                 strncpy(state->desc, "SuperH Mobile Standby Mode [SF]",
                         CPUIDLE_DESC_LEN);
@@ -114,7 +115,10 @@ void sh_mobile_setup_cpuidle(void)
                 state->enter = cpuidle_sleep_enter;
         }
 
+        drv->state_count = i;
         dev->state_count = i;
 
+        cpuidle_register_driver(&cpuidle_driver);
+
         cpuidle_register_device(dev);
 }