Instead of parsing all EM table everytime, add a function to get the
previous state.

Will be used in the scheduler feec() function.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
 include/linux/energy_model.h | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index 752e0b297582..26d0ff72feac 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -215,6 +215,26 @@ em_pd_get_efficient_state(struct em_perf_state *table,
 	return max_ps;
 }
 
+static inline int
+em_pd_get_previous_state(struct em_perf_state *table,
+			 struct em_perf_domain *pd, int idx)
+{
+	unsigned long pd_flags = pd->flags;
+	int min_ps = pd->min_perf_state;
+	struct em_perf_state *ps;
+	int i;
+
+	for (i = idx - 1; i >= min_ps; i--) {
+		ps = &table[i];
+		if (pd_flags & EM_PERF_DOMAIN_SKIP_INEFFICIENCIES &&
+		    ps->flags & EM_PERF_STATE_INEFFICIENT)
+			continue;
+		return i;
+	}
+
+	return -1;
+}
+
 /**
  * em_cpu_energy() - Estimates the energy consumed by the CPUs of a
  *		performance domain
@@ -361,6 +381,19 @@ static inline struct em_perf_domain *em_pd_get(struct device *dev)
 {
 	return NULL;
 }
+static inline int
+em_pd_get_efficient_state(struct em_perf_state *table,
+			  struct em_perf_domain *pd, unsigned long max_util)
+{
+	return 0;
+}
+
+static inline int
+em_pd_get_previous_state(struct em_perf_state *table, int nr_perf_states,
+			  int idx, unsigned long pd_flags)
+{
+	return -1;
+}
 static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
 			unsigned long max_util, unsigned long sum_util,
 			unsigned long allowed_cpu_cap)
-- 
2.43.0