[PATCH v2 05/10] PM: EM: Add an iterator and accessor for the performance domain.

[Changwoo Min <changwoo@igalia.com>]

Add an iterator function (for_each_em_perf_domain) that iterates all the
performance domains in the global list. A passed callback function (cb) is
called for each performance domain.

Additionally, add a lookup function (em_perf_domain_get_by_id) that
searches for a performance domain by matching the ID in the global list.

Signed-off-by: Changwoo Min <changwoo@igalia.com>
---
 include/linux/energy_model.h | 15 +++++++++++++++
 kernel/power/energy_model.c  | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index 2f5c73fcdfe5..ce70e664fcd4 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -341,6 +341,10 @@ struct em_perf_state *em_perf_state_from_pd(struct em_perf_domain *pd)
 	return rcu_dereference(pd->em_table)->state;
 }
 
+int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
+			    void *data);
+struct em_perf_domain *em_perf_domain_get_by_id(int id);
+
 #else
 struct em_data_callback {};
 #define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) { }
@@ -410,6 +414,17 @@ int em_update_performance_limits(struct em_perf_domain *pd,
 }
 static inline void em_adjust_cpu_capacity(unsigned int cpu) {}
 static inline void em_rebuild_sched_domains(void) {}
+static inline
+int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
+			    void *data)
+{
+	return -EINVAL;
+}
+static inline
+struct em_perf_domain *em_perf_domain_get_by_id(int id)
+{
+	return NULL;
+}
 #endif
 
 #endif
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 6e5e70dbec88..f125262a93c9 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -976,3 +976,37 @@ void em_rebuild_sched_domains(void)
 	 */
 	schedule_work(&rebuild_sd_work);
 }
+
+int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
+			    void *data)
+{
+	struct em_perf_domain *pd;
+
+	lockdep_assert_not_held(&em_pd_mutex);
+	guard(mutex)(&em_pd_list_mutex);
+
+	list_for_each_entry(pd, &em_pd_list, node) {
+		int ret;
+
+		ret = cb(pd, data);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+struct em_perf_domain *em_perf_domain_get_by_id(int id)
+{
+	struct em_perf_domain *pd;
+
+	lockdep_assert_not_held(&em_pd_mutex);
+	guard(mutex)(&em_pd_list_mutex);
+
+	list_for_each_entry(pd, &em_pd_list, node) {
+		if (pd->id == id)
+			return pd;
+	}
+
+	return NULL;
+}
-- 
2.49.0