regulator: Split up _regulator_get()

_regulator_get() contains a lot of common code doing checks prior to the
regulator lookup and housekeeping work after the lookup. Almost all the
code could be shared with a OF-specific variant of _regulator_get().

Split out the common parts so that they can be reused. The OF-specific
version of _regulator_get() will be added in a subsequent patch.
No functional changes were made.

Signed-off-by: Chen-Yu Tsai <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/regulator/core.c

···
 	return ret;
 }
 
-/* Internal regulator request function */
-struct regulator *_regulator_get(struct device *dev, const char *id,
-				 enum regulator_get_type get_type)
+/* common pre-checks for regulator requests */
+int _regulator_get_common_check(struct device *dev, const char *id,
+				enum regulator_get_type get_type)
 {
-	struct regulator_dev *rdev;
-	struct regulator *regulator;
-	struct device_link *link;
-	int ret;
-
 	if (get_type >= MAX_GET_TYPE) {
 		dev_err(dev, "invalid type %d in %s\n", get_type, __func__);
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 	}
 
 	if (id == NULL) {
 		dev_err(dev, "regulator request with no identifier\n");
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 	}
 
-	rdev = regulator_dev_lookup(dev, id);
+	return 0;
+}
+
+/**
+ * _regulator_get_common - Common code for regulator requests
+ * @rdev: regulator device pointer as returned by *regulator_dev_lookup()
+ *       Its reference count is expected to have been incremented.
+ * @dev: device used for dev_printk messages
+ * @id: Supply name or regulator ID
+ * @get_type: enum regulator_get_type value corresponding to type of request
+ *
+ * Returns: pointer to struct regulator corresponding to @rdev, or ERR_PTR()
+ *	    encoded error.
+ *
+ * This function should be chained with *regulator_dev_lookup() functions.
+ */
+struct regulator *_regulator_get_common(struct regulator_dev *rdev, struct device *dev,
+					const char *id, enum regulator_get_type get_type)
+{
+	struct regulator *regulator;
+	struct device_link *link;
+	int ret;
+
 	if (IS_ERR(rdev)) {
 		ret = PTR_ERR(rdev);
 
···
 		regulator->device_link = true;
 
 	return regulator;
+}
+
+/* Internal regulator request function */
+struct regulator *_regulator_get(struct device *dev, const char *id,
+				 enum regulator_get_type get_type)
+{
+	struct regulator_dev *rdev;
+	int ret;
+
+	ret = _regulator_get_common_check(dev, id, get_type);
+	if (ret)
+		return ERR_PTR(ret);
+
+	rdev = regulator_dev_lookup(dev, id);
+	return _regulator_get_common(rdev, dev, id, get_type);
 }
 
 /**

drivers/regulator/internal.h

···
 	MAX_GET_TYPE
 };
 
+int _regulator_get_common_check(struct device *dev, const char *id,
+				enum regulator_get_type get_type);
+struct regulator *_regulator_get_common(struct regulator_dev *rdev, struct device *dev,
+					const char *id, enum regulator_get_type get_type);
 struct regulator *_regulator_get(struct device *dev, const char *id,
 				 enum regulator_get_type get_type);
 int _regulator_bulk_get(struct device *dev, int num_consumers,