power_supply: Add core support for supplied_from

This patch adds support for supplies to register a list of char *'s which
represent the list of supplies which supply them. This is the opposite as
the supplied_to list.

This change maintains support for supplied_to until all drivers which make
use of it already are converted.
Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>

drivers/power/power_supply_core.c

@@ -26,17 +26,42 @@ EXPORT_SYMBOL_GPL(power_supply_class);
 
 static struct device_type power_supply_dev_type;
 
+static bool __power_supply_is_supplied_by(struct power_supply *supplier,
+					 struct power_supply *supply)
+{
+	int i;
+
+	if (!supply->supplied_from && !supplier->supplied_to)
+		return false;
+
+	/* Support both supplied_to and supplied_from modes */
+	if (supply->supplied_from) {
+		if (!supplier->name)
+			return false;
+		for (i = 0; i < supply->num_supplies; i++)
+			if (!strcmp(supplier->name, supply->supplied_from[i]))
+				return true;
+	} else {
+		if (!supply->name)
+			return false;
+		for (i = 0; i < supplier->num_supplicants; i++)
+			if (!strcmp(supplier->supplied_to[i], supply->name))
+				return true;
+	}
+
+	return false;
+}
+
 static int __power_supply_changed_work(struct device *dev, void *data)
 {
 	struct power_supply *psy = (struct power_supply *)data;
 	struct power_supply *pst = dev_get_drvdata(dev);
-	int i;
 
-	for (i = 0; i < psy->num_supplicants; i++)
-		if (!strcmp(psy->supplied_to[i], pst->name)) {
-			if (pst->external_power_changed)
-				pst->external_power_changed(pst);
-		}
+	if (__power_supply_is_supplied_by(psy, pst)) {
+		if (pst->external_power_changed)
+			pst->external_power_changed(pst);
+	}
+
 	return 0;
 }
 
@@ -68,17 +93,13 @@ static int __power_supply_am_i_supplied(struct device *dev, void *data)
 	union power_supply_propval ret = {0,};
 	struct power_supply *psy = (struct power_supply *)data;
 	struct power_supply *epsy = dev_get_drvdata(dev);
-	int i;
 
-	for (i = 0; i < epsy->num_supplicants; i++) {
-		if (!strcmp(epsy->supplied_to[i], psy->name)) {
-			if (epsy->get_property(epsy,
-				  POWER_SUPPLY_PROP_ONLINE, &ret))
-				continue;
+	if (__power_supply_is_supplied_by(epsy, psy))
+		if (!epsy->get_property(epsy, POWER_SUPPLY_PROP_ONLINE, &ret)) {
 			if (ret.intval)
 				return ret.intval;
 		}
-	}
+
 	return 0;
 }
 

include/linux/power_supply.h

@@ -171,6 +171,9 @@ struct power_supply {
 	char **supplied_to;
 	size_t num_supplicants;
 
+	char **supplied_from;
+	size_t num_supplies;
+
 	int (*get_property)(struct power_supply *psy,
 			    enum power_supply_property psp,
 			    union power_supply_propval *val);