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, 49 insertions, 24 deletions

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index d3fce7b97fcf..1fe35c24fba2 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -88,12 +88,14 @@ static int _cpuidle_deny_idle(struct powerdomain *pwrdm,
 /**
  * omap3_enter_idle - Programs OMAP3 to enter the specified state
  * @dev: cpuidle device
+ * @drv: cpuidle driver
  * @index: the index of state to be entered
  *
  * Called from the CPUidle framework to program the device to the
  * specified target state selected by the governor.
  */
 static int omap3_enter_idle(struct cpuidle_device *dev,
+                                struct cpuidle_driver *drv,
                                 int index)
 {
         struct omap3_idle_statedata *cx =
@@ -148,6 +150,7 @@ return_sleep_time:
 /**
  * next_valid_state - Find next valid C-state
  * @dev: cpuidle device
+ * @drv: cpuidle driver
  * @index: Index of currently selected c-state
  *
  * If the state corresponding to index is valid, index is returned back
@@ -158,10 +161,11 @@ return_sleep_time:
  * if it satisfies the enable_off_mode condition.
  */
 static int next_valid_state(struct cpuidle_device *dev,
+                        struct cpuidle_driver *drv,
                                 int index)
 {
         struct cpuidle_state_usage *curr_usage = &dev->states_usage[index];
-        struct cpuidle_state *curr = &dev->states[index];
+        struct cpuidle_state *curr = &drv->states[index];
         struct omap3_idle_statedata *cx = cpuidle_get_statedata(curr_usage);
         u32 mpu_deepest_state = PWRDM_POWER_RET;
         u32 core_deepest_state = PWRDM_POWER_RET;
@@ -188,7 +192,7 @@ static int next_valid_state(struct cpuidle_device *dev,
 
                 /* Reach the current state starting at highest C-state */
                 for (; idx >= 0; idx--) {
-                        if (&dev->states[idx] == curr) {
+                        if (&drv->states[idx] == curr) {
                                 next_index = idx;
                                 break;
                         }
@@ -224,12 +228,14 @@ static int next_valid_state(struct cpuidle_device *dev,
 /**
  * omap3_enter_idle_bm - Checks for any bus activity
  * @dev: cpuidle device
+ * @drv: cpuidle driver
  * @index: array index of target state to be programmed
  *
  * This function checks for any pending activity and then programs
  * the device to the specified or a safer state.
  */
 static int omap3_enter_idle_bm(struct cpuidle_device *dev,
+                                struct cpuidle_driver *drv,
                                int index)
 {
         int new_state_idx;
@@ -238,7 +244,7 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
         int ret;
 
         if (!omap3_can_sleep()) {
-                new_state_idx = dev->safe_state_index;
+                new_state_idx = drv->safe_state_index;
                 goto select_state;
         }
 
@@ -248,7 +254,7 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
          */
         cam_state = pwrdm_read_pwrst(cam_pd);
         if (cam_state == PWRDM_POWER_ON) {
-                new_state_idx = dev->safe_state_index;
+                new_state_idx = drv->safe_state_index;
                 goto select_state;
         }
 
@@ -275,10 +281,10 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
         if (per_next_state != per_saved_state)
                 pwrdm_set_next_pwrst(per_pd, per_next_state);
 
-        new_state_idx = next_valid_state(dev, index);
+        new_state_idx = next_valid_state(dev, drv, index);
 
 select_state:
-        ret = omap3_enter_idle(dev, new_state_idx);
+        ret = omap3_enter_idle(dev, drv, new_state_idx);
 
         /* Restore original PER state if it was modified */
         if (per_next_state != per_saved_state)
@@ -311,22 +317,30 @@ struct cpuidle_driver omap3_idle_driver = {
         .owner =        THIS_MODULE,
 };
 
-/* Helper to fill the C-state common data and register the driver_data */
-static inline struct omap3_idle_statedata *_fill_cstate(
-                                        struct cpuidle_device *dev,
+/* Helper to fill the C-state common data*/
+static inline void _fill_cstate(struct cpuidle_driver *drv,
                                         int idx, const char *descr)
 {
-        struct omap3_idle_statedata *cx = &omap3_idle_data[idx];
-        struct cpuidle_state *state = &dev->states[idx];
-        struct cpuidle_state_usage *state_usage = &dev->states_usage[idx];
+        struct cpuidle_state *state = &drv->states[idx];
 
         state->exit_latency     = cpuidle_params_table[idx].exit_latency;
         state->target_residency = cpuidle_params_table[idx].target_residency;
         state->flags            = CPUIDLE_FLAG_TIME_VALID;
         state->enter            = omap3_enter_idle_bm;
-        cx->valid               = cpuidle_params_table[idx].valid;
         sprintf(state->name, "C%d", idx + 1);
         strncpy(state->desc, descr, CPUIDLE_DESC_LEN);
+
+}
+
+/* Helper to register the driver_data */
+static inline struct omap3_idle_statedata *_fill_cstate_usage(
+                                        struct cpuidle_device *dev,
+                                        int idx)
+{
+        struct omap3_idle_statedata *cx = &omap3_idle_data[idx];
+        struct cpuidle_state_usage *state_usage = &dev->states_usage[idx];
+
+        cx->valid               = cpuidle_params_table[idx].valid;
         cpuidle_set_statedata(state_usage, cx);
 
         return cx;
@@ -341,6 +355,7 @@ static inline struct omap3_idle_statedata *_fill_cstate(
 int __init omap3_idle_init(void)
 {
         struct cpuidle_device *dev;
+        struct cpuidle_driver *drv = &omap3_idle_driver;
         struct omap3_idle_statedata *cx;
 
         mpu_pd = pwrdm_lookup("mpu_pwrdm");
@@ -348,45 +363,52 @@ int __init omap3_idle_init(void)
         per_pd = pwrdm_lookup("per_pwrdm");
         cam_pd = pwrdm_lookup("cam_pwrdm");
 
-        cpuidle_register_driver(&omap3_idle_driver);
+
+        drv->safe_state_index = -1;
         dev = &per_cpu(omap3_idle_dev, smp_processor_id());
-        dev->safe_state_index = -1;
 
         /* C1 . MPU WFI + Core active */
-        cx = _fill_cstate(dev, 0, "MPU ON + CORE ON");
-        (&dev->states[0])->enter = omap3_enter_idle;
-        dev->safe_state_index = 0;
+        _fill_cstate(drv, 0, "MPU ON + CORE ON");
+        (&drv->states[0])->enter = omap3_enter_idle;
+        drv->safe_state_index = 0;
+        cx = _fill_cstate_usage(dev, 0);
         cx->valid = 1;  /* C1 is always valid */
         cx->mpu_state = PWRDM_POWER_ON;
         cx->core_state = PWRDM_POWER_ON;
 
         /* C2 . MPU WFI + Core inactive */
-        cx = _fill_cstate(dev, 1, "MPU ON + CORE ON");
+        _fill_cstate(drv, 1, "MPU ON + CORE ON");
+        cx = _fill_cstate_usage(dev, 1);
         cx->mpu_state = PWRDM_POWER_ON;
         cx->core_state = PWRDM_POWER_ON;
 
         /* C3 . MPU CSWR + Core inactive */
-        cx = _fill_cstate(dev, 2, "MPU RET + CORE ON");
+        _fill_cstate(drv, 2, "MPU RET + CORE ON");
+        cx = _fill_cstate_usage(dev, 2);
         cx->mpu_state = PWRDM_POWER_RET;
         cx->core_state = PWRDM_POWER_ON;
 
         /* C4 . MPU OFF + Core inactive */
-        cx = _fill_cstate(dev, 3, "MPU OFF + CORE ON");
+        _fill_cstate(drv, 3, "MPU OFF + CORE ON");
+        cx = _fill_cstate_usage(dev, 3);
         cx->mpu_state = PWRDM_POWER_OFF;
         cx->core_state = PWRDM_POWER_ON;
 
         /* C5 . MPU RET + Core RET */
-        cx = _fill_cstate(dev, 4, "MPU RET + CORE RET");
+        _fill_cstate(drv, 4, "MPU RET + CORE RET");
+        cx = _fill_cstate_usage(dev, 4);
         cx->mpu_state = PWRDM_POWER_RET;
         cx->core_state = PWRDM_POWER_RET;
 
         /* C6 . MPU OFF + Core RET */
-        cx = _fill_cstate(dev, 5, "MPU OFF + CORE RET");
+        _fill_cstate(drv, 5, "MPU OFF + CORE RET");
+        cx = _fill_cstate_usage(dev, 5);
         cx->mpu_state = PWRDM_POWER_OFF;
         cx->core_state = PWRDM_POWER_RET;
 
         /* C7 . MPU OFF + Core OFF */
-        cx = _fill_cstate(dev, 6, "MPU OFF + CORE OFF");
+        _fill_cstate(drv, 6, "MPU OFF + CORE OFF");
+        cx = _fill_cstate_usage(dev, 6);
         /*
          * Erratum i583: implementation for ES rev < Es1.2 on 3630. We cannot
          * enable OFF mode in a stable form for previous revisions.
@@ -400,6 +422,9 @@ int __init omap3_idle_init(void)
         cx->mpu_state = PWRDM_POWER_OFF;
         cx->core_state = PWRDM_POWER_OFF;
 
+        drv->state_count = OMAP3_NUM_STATES;
+        cpuidle_register_driver(&omap3_idle_driver);
+
         dev->state_count = OMAP3_NUM_STATES;
         if (cpuidle_register_device(dev)) {
                 printk(KERN_ERR "%s: CPUidle register device failed\n",