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, 12 insertions, 33 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 7127e92fa8a1..7a57b11eaa8d 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -61,6 +61,7 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
 int cpuidle_idle_call(void)
 {
         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
+        struct cpuidle_driver *drv = cpuidle_get_driver();
         struct cpuidle_state *target_state;
         int next_state, entered_state;
 
@@ -84,18 +85,18 @@ int cpuidle_idle_call(void)
 #endif
 
         /* ask the governor for the next state */
-        next_state = cpuidle_curr_governor->select(dev);
+        next_state = cpuidle_curr_governor->select(drv, dev);
         if (need_resched()) {
                 local_irq_enable();
                 return 0;
         }
 
-        target_state = &dev->states[next_state];
+        target_state = &drv->states[next_state];
 
         trace_power_start(POWER_CSTATE, next_state, dev->cpu);
         trace_cpu_idle(next_state, dev->cpu);
 
-        entered_state = target_state->enter(dev, next_state);
+        entered_state = target_state->enter(dev, drv, next_state);
 
         trace_power_end(dev->cpu);
         trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
@@ -163,7 +164,8 @@ void cpuidle_resume_and_unlock(void)
 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 
 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
-static int poll_idle(struct cpuidle_device *dev, int index)
+static int poll_idle(struct cpuidle_device *dev,
+                struct cpuidle_driver *drv, int index)
 {
         ktime_t t1, t2;
         s64 diff;
@@ -183,12 +185,9 @@ static int poll_idle(struct cpuidle_device *dev, int index)
         return index;
 }
 
-static void poll_idle_init(struct cpuidle_device *dev)
+static void poll_idle_init(struct cpuidle_driver *drv)
 {
-        struct cpuidle_state *state = &dev->states[0];
-        struct cpuidle_state_usage *state_usage = &dev->states_usage[0];
-
-        cpuidle_set_statedata(state_usage, NULL);
+        struct cpuidle_state *state = &drv->states[0];
 
         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
@@ -199,7 +198,7 @@ static void poll_idle_init(struct cpuidle_device *dev)
         state->enter = poll_idle;
 }
 #else
-static void poll_idle_init(struct cpuidle_device *dev) {}
+static void poll_idle_init(struct cpuidle_driver *drv) {}
 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
 
 /**
@@ -226,13 +225,13 @@ int cpuidle_enable_device(struct cpuidle_device *dev)
                         return ret;
         }
 
-        poll_idle_init(dev);
+        poll_idle_init(cpuidle_get_driver());
 
         if ((ret = cpuidle_add_state_sysfs(dev)))
                 return ret;
 
         if (cpuidle_curr_governor->enable &&
-            (ret = cpuidle_curr_governor->enable(dev)))
+            (ret = cpuidle_curr_governor->enable(cpuidle_get_driver(), dev)))
                 goto fail_sysfs;
 
         for (i = 0; i < dev->state_count; i++) {
@@ -273,7 +272,7 @@ void cpuidle_disable_device(struct cpuidle_device *dev)
         dev->enabled = 0;
 
         if (cpuidle_curr_governor->disable)
-                cpuidle_curr_governor->disable(dev);
+                cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
 
         cpuidle_remove_state_sysfs(dev);
         enabled_devices--;
@@ -301,26 +300,6 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
 
         init_completion(&dev->kobj_unregister);
 
-        /*
-         * cpuidle driver should set the dev->power_specified bit
-         * before registering the device if the driver provides
-         * power_usage numbers.
-         *
-         * For those devices whose ->power_specified is not set,
-         * we fill in power_usage with decreasing values as the
-         * cpuidle code has an implicit assumption that state Cn
-         * uses less power than C(n-1).
-         *
-         * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
-         * an power value of -1.  So we use -2, -3, etc, for other
-         * c-states.
-         */
-        if (!dev->power_specified) {
-                int i;
-                for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
-                        dev->states[i].power_usage = -1 - i;
-        }
-
         per_cpu(cpuidle_devices, dev->cpu) = dev;
         list_add(&dev->device_list, &cpuidle_detected_devices);
         if ((ret = cpuidle_add_sysfs(sys_dev))) {