regulator: Add devm_regulator_get()

Add a resource managed regulator_get() to simplify regulator
usage in drivers. This allows driver authors to "get and forget"
about their regulators by automatically calling regulator_put()
when the driver is detached.

[Fixed up a couple of coding style issues -- broonie]

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Documentation/driver-model/devres.txt

@@ -267,3 +267,6 @@ IOMAP
   pcim_iounmap()
   pcim_iomap_table()	: array of mapped addresses indexed by BAR
   pcim_iomap_regions()	: do request_region() and iomap() on multiple BARs
+
+REGULATOR
+  devm_regulator_get()

drivers/regulator/core.c

@@ -1320,6 +1320,40 @@ struct regulator *regulator_get(struct device *dev, const char *id)
 }
 EXPORT_SYMBOL_GPL(regulator_get);
 
+static void devm_regulator_release(struct device *dev, void *res)
+{
+	regulator_put(*(struct regulator **)res);
+}
+
+/**
+ * devm_regulator_get - Resource managed regulator_get()
+ * @dev: device for regulator "consumer"
+ * @id: Supply name or regulator ID.
+ *
+ * Managed regulator_get(). Regulators returned from this function are
+ * automatically regulator_put() on driver detach. See regulator_get() for more
+ * information.
+ */
+struct regulator *devm_regulator_get(struct device *dev, const char *id)
+{
+	struct regulator **ptr, *regulator;
+
+	ptr = devres_alloc(devm_regulator_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	regulator = regulator_get(dev, id);
+	if (!IS_ERR(regulator)) {
+		*ptr = regulator;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return regulator;
+}
+EXPORT_SYMBOL_GPL(devm_regulator_get);
+
 /**
  * regulator_get_exclusive - obtain exclusive access to a regulator.
  * @dev: device for regulator "consumer"

include/linux/regulator/consumer.h

@@ -132,6 +132,8 @@ struct regulator_bulk_data {
 /* regulator get and put */
 struct regulator *__must_check regulator_get(struct device *dev,
 					     const char *id);
+struct regulator *__must_check devm_regulator_get(struct device *dev,
+					     const char *id);
 struct regulator *__must_check regulator_get_exclusive(struct device *dev,
 						       const char *id);
 void regulator_put(struct regulator *regulator);
@@ -200,6 +202,13 @@ static inline struct regulator *__must_check regulator_get(struct device *dev,
 	 */
 	return NULL;
 }
+
+static inline struct regulator *__must_check
+devm_regulator_get(struct device *dev, const char *id)
+{
+	return NULL;
+}
+
 static inline void regulator_put(struct regulator *regulator)
 {
 }