regulator: Allow parsing custom properties when using simplified DT parsing

When drivers use simplified DT parsing method (they provide
'regulator_desc.of_match') they still may want to parse custom
properties for some of the regulators. For example some of the
regulators support GPIO enable control.

Add a driver-supplied callback for such case. This way the regulator
core parses common bindings offloading a lot of code from drivers and
still custom properties may be used.

The callback, called for each parsed regulator, may modify the
'regulator_config' initially passed to regulator_register().

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/regulator/core.c

···
 		return ERR_PTR(-ENOMEM);
 	}
 
-	init_data = regulator_of_get_init_data(dev, regulator_desc,
+	init_data = regulator_of_get_init_data(dev, regulator_desc, config,
 					       &rdev->dev.of_node);
 	if (!init_data) {
 		init_data = config->init_data;

drivers/regulator/internal.h

···
 #ifdef CONFIG_OF
 struct regulator_init_data *regulator_of_get_init_data(struct device *dev,
 			         const struct regulator_desc *desc,
+				 struct regulator_config *config,
 				 struct device_node **node);
 #else
 static inline struct regulator_init_data *
 regulator_of_get_init_data(struct device *dev,
 			   const struct regulator_desc *desc,
+			   struct regulator_config *config,
 			   struct device_node **node)
 {
 	return NULL;

drivers/regulator/of_regulator.c

···
 
 struct regulator_init_data *regulator_of_get_init_data(struct device *dev,
 					    const struct regulator_desc *desc,
+					    struct regulator_config *config,
 					    struct device_node **node)
 {
 	struct device_node *search, *child;
···
 				"failed to parse DT for regulator %s\n",
 				child->name);
 			break;
+		}
+
+		if (desc->of_parse_cb) {
+			if (desc->of_parse_cb(child, desc, config)) {
+				dev_err(dev,
+					"driver callback failed to parse DT for regulator %s\n",
+					child->name);
+				init_data = NULL;
+				break;
+			}
 		}
 
 		of_node_get(child);

include/linux/regulator/driver.h

···
 
 struct regmap;
 struct regulator_dev;
+struct regulator_config;
 struct regulator_init_data;
 struct regulator_enable_gpio;
 
···
  * @supply_name: Identifying the regulator supply
  * @of_match: Name used to identify regulator in DT.
  * @regulators_node: Name of node containing regulator definitions in DT.
+ * @of_parse_cb: Optional callback called only if of_match is present.
+ *               Will be called for each regulator parsed from DT, during
+ *               init_data parsing.
+ *               The regulator_config passed as argument to the callback will
+ *               be a copy of config passed to regulator_register, valid only
+ *               for this particular call. Callback may freely change the
+ *               config but it cannot store it for later usage.
+ *               Callback should return 0 on success or negative ERRNO
+ *               indicating failure.
  * @id: Numerical identifier for the regulator.
  * @ops: Regulator operations table.
  * @irq: Interrupt number for the regulator.
···
 	const char *supply_name;
 	const char *of_match;
 	const char *regulators_node;
+	int (*of_parse_cb)(struct device_node *,
+			    const struct regulator_desc *,
+			    struct regulator_config *);
 	int id;
 	bool continuous_voltage_range;
 	unsigned n_voltages;