regulator: core: Get and put regulator of_node

Currently the regulator core does not take an additional reference to
the of_node it is passed. This means that the caller must ensure that
the of_node is valid for the duration of the regulator's existance.
It is reasonable for the framework to assume it is passed a valid
of_node but seems onerous for it to assume the caller will keep the node
valid for the life-time of the regulator, especially when
devm_regulator_register is used and there will likely be no code in the
driver called at the point it would be safe to put the of_node.

This patch adds an additional of_node_get when the regulator is
registered and an of_node_put when it is unregistered in the core. This
means individual drivers are free to put their of_node references at the
end of probe letting the regulator core handling it from there. This
simplifies code on the driver side.
Signed-off-by: NCharles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: NMark Brown <broonie@linaro.org>

drivers/regulator/core.c

@@ -3447,7 +3447,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
 
 	/* register with sysfs */
 	rdev->dev.class = &regulator_class;
-	rdev->dev.of_node = config->of_node;
+	rdev->dev.of_node = of_node_get(config->of_node);
 	rdev->dev.parent = dev;
 	dev_set_name(&rdev->dev, "regulator.%d",
 		     atomic_inc_return(&regulator_no) - 1);
@@ -3589,6 +3589,7 @@ void regulator_unregister(struct regulator_dev *rdev)
 	list_del(&rdev->list);
 	kfree(rdev->constraints);
 	regulator_ena_gpio_free(rdev);
+	of_node_put(rdev->dev.of_node);
 	device_unregister(&rdev->dev);
 	mutex_unlock(&regulator_list_mutex);
 }