regulator: core: Add regulator_is_equal() helper

Add regulator_is_equal() helper to compare whether two regulators are
the same. This is useful for checking whether two separate regulators
in a driver are actually the same supply.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Igor Opaniuk <igor.opaniuk@toradex.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Link: https://lore.kernel.org/r/20191220164450.1395038-1-marex@denx.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/helpers.c

@@ -13,6 +13,8 @@
 #include <linux/regulator/driver.h>
 #include <linux/module.h>
 
+#include "internal.h"
+
 /**
  * regulator_is_enabled_regmap - standard is_enabled() for regmap users
  *
@@ -881,3 +883,15 @@ void regulator_bulk_set_supply_names(struct regulator_bulk_data *consumers,
 		consumers[i].supply = supply_names[i];
 }
 EXPORT_SYMBOL_GPL(regulator_bulk_set_supply_names);
+
+/**
+ * regulator_is_equal - test whether two regulators are the same
+ *
+ * @reg1: first regulator to operate on
+ * @reg2: second regulator to operate on
+ */
+bool regulator_is_equal(struct regulator *reg1, struct regulator *reg2)
+{
+	return reg1->rdev == reg2->rdev;
+}
+EXPORT_SYMBOL_GPL(regulator_is_equal);

include/linux/regulator/consumer.h

@@ -287,6 +287,8 @@ void regulator_bulk_set_supply_names(struct regulator_bulk_data *consumers,
 				     const char *const *supply_names,
 				     unsigned int num_supplies);
 
+bool regulator_is_equal(struct regulator *reg1, struct regulator *reg2);
+
 #else
 
 /*
@@ -593,6 +595,11 @@ regulator_bulk_set_supply_names(struct regulator_bulk_data *consumers,
 {
 }
 
+static inline bool
+regulator_is_equal(struct regulator *reg1, struct regulator *reg2);
+{
+	return false;
+}
 #endif
 
 static inline int regulator_set_voltage_triplet(struct regulator *regulator,