ANDROID: sched, cpuidle: Track cpuidle state index in the scheduler

The idle-state of each cpu is currently pointed to by rq->idle_state but
there isn't any information in the struct cpuidle_state that can used to
look up the idle-state energy model data stored in struct
sched_group_energy. For this purpose is necessary to store the idle
state index as well. Ideally, the idle-state data should be unified.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Andres Oportus <andresoportus@google.com>
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 690bfb6..86512af 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -722,6 +722,7 @@
 #ifdef CONFIG_CPU_IDLE
 	/* Must be inspected within a rcu lock section */
 	struct cpuidle_state *idle_state;
+	int idle_state_idx;
 #endif
 };
 
@@ -1329,6 +1330,17 @@
 	SCHED_WARN_ON(!rcu_read_lock_held());
 	return rq->idle_state;
 }
+
+static inline void idle_set_state_idx(struct rq *rq, int idle_state_idx)
+{
+	rq->idle_state_idx = idle_state_idx;
+}
+
+static inline int idle_get_state_idx(struct rq *rq)
+{
+	WARN_ON(!rcu_read_lock_held());
+	return rq->idle_state_idx;
+}
 #else
 static inline void idle_set_state(struct rq *rq,
 				  struct cpuidle_state *idle_state)
@@ -1339,6 +1351,15 @@
 {
 	return NULL;
 }
+
+static inline void idle_set_state_idx(struct rq *rq, int idle_state_idx)
+{
+}
+
+static inline int idle_get_state_idx(struct rq *rq)
+{
+	return -1;
+}
 #endif
 
 extern void sysrq_sched_debug_show(void);