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, 10 deletions

diff --git a/arch/arm/mach-exynos4/cpuidle.c b/arch/arm/mach-exynos4/cpuidle.c
index ea026e72b977..35f6502144ae 100644
--- a/arch/arm/mach-exynos4/cpuidle.c
+++ b/arch/arm/mach-exynos4/cpuidle.c
@@ -16,6 +16,7 @@
 #include <asm/proc-fns.h>
 
 static int exynos4_enter_idle(struct cpuidle_device *dev,
+			struct cpuidle_driver *drv,
 			      int index);
 
 static struct cpuidle_state exynos4_cpuidle_set[] = {
@@ -37,6 +38,7 @@ static struct cpuidle_driver exynos4_idle_driver = {
 };
 
 static int exynos4_enter_idle(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv,
 			      int index)
 {
 	struct timeval before, after;
@@ -60,22 +62,23 @@ static int __init exynos4_init_cpuidle(void)
 {
 	int i, max_cpuidle_state, cpu_id;
 	struct cpuidle_device *device;
-
+	struct cpuidle_driver *drv = &exynos4_idle_driver;
+
+	/* Setup cpuidle driver */
+	drv->state_count = (sizeof(exynos4_cpuidle_set) /
+				       sizeof(struct cpuidle_state));
+	max_cpuidle_state = drv->state_count;
+	for (i = 0; i < max_cpuidle_state; i++) {
+		memcpy(&drv->states[i], &exynos4_cpuidle_set[i],
+				sizeof(struct cpuidle_state));
+	}
 	cpuidle_register_driver(&exynos4_idle_driver);
 
 	for_each_cpu(cpu_id, cpu_online_mask) {
 		device = &per_cpu(exynos4_cpuidle_device, cpu_id);
 		device->cpu = cpu_id;
 
-		device->state_count = (sizeof(exynos4_cpuidle_set) /
-					       sizeof(struct cpuidle_state));
-
-		max_cpuidle_state = device->state_count;
-
-		for (i = 0; i < max_cpuidle_state; i++) {
-			memcpy(&device->states[i], &exynos4_cpuidle_set[i],
-					sizeof(struct cpuidle_state));
-		}
+		device->state_count = drv->state_count;
 
 		if (cpuidle_register_device(device)) {
 			printk(KERN_ERR "CPUidle register device failed\n,");