PM: EM: Add em_dev_update_chip_binning()

Add a function which allows to modify easily the EM after the new voltage
information is available. The device drivers for the chip can adjust
the voltage values after setup. The voltage for the same frequency in OPP
can be different due to chip binning. The voltage impacts the power usage
and the EM power values can be updated to reflect that.
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/energy_model.h

@@ -172,6 +172,7 @@ struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd);
 void em_table_free(struct em_perf_table __rcu *table);
 int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
 			 int nr_states);
+int em_dev_update_chip_binning(struct device *dev);
 
 /**
  * em_pd_get_efficient_state() - Get an efficient performance state from the EM
@@ -386,6 +387,10 @@ int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
 {
 	return -EINVAL;
 }
+static inline int em_dev_update_chip_binning(struct device *dev)
+{
+	return -EINVAL;
+}
 #endif
 
 #endif

kernel/power/energy_model.c

@@ -808,3 +808,51 @@ static void em_update_workfn(struct work_struct *work)
 {
 	em_check_capacity_update();
 }
+
+/**
+ * em_dev_update_chip_binning() - Update Energy Model after the new voltage
+ *				information is present in the OPPs.
+ * @dev		: Device for which the Energy Model has to be updated.
+ *
+ * This function allows to update easily the EM with new values available in
+ * the OPP framework and DT. It can be used after the chip has been properly
+ * verified by device drivers and the voltages adjusted for the 'chip binning'.
+ */
+int em_dev_update_chip_binning(struct device *dev)
+{
+	struct em_perf_table __rcu *em_table;
+	struct em_perf_domain *pd;
+	int i, ret;
+
+	if (IS_ERR_OR_NULL(dev))
+		return -EINVAL;
+
+	pd = em_pd_get(dev);
+	if (!pd) {
+		dev_warn(dev, "Couldn't find Energy Model\n");
+		return -EINVAL;
+	}
+
+	em_table = em_table_dup(pd);
+	if (!em_table) {
+		dev_warn(dev, "EM: allocation failed\n");
+		return -ENOMEM;
+	}
+
+	/* Update power values which might change due to new voltage in OPPs */
+	for (i = 0; i < pd->nr_perf_states; i++) {
+		unsigned long freq = em_table->state[i].frequency;
+		unsigned long power;
+
+		ret = dev_pm_opp_calc_power(dev, &power, &freq);
+		if (ret) {
+			em_table_free(em_table);
+			return ret;
+		}
+
+		em_table->state[i].power = power;
+	}
+
+	return em_recalc_and_update(dev, pd, em_table);
+}
+EXPORT_SYMBOL_GPL(em_dev_update_chip_binning);