i2c: Add i2c_get_match_data()

Add i2c_get_match_data() to get match data for I2C, ACPI and
DT-based matching, so that we can optimize the driver code.
Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
[wsa: simplified var initialization]
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/i2c-core-base.c

@@ -114,6 +114,25 @@ const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
 }
 EXPORT_SYMBOL_GPL(i2c_match_id);
 
+const void *i2c_get_match_data(const struct i2c_client *client)
+{
+	struct i2c_driver *driver = to_i2c_driver(client->dev.driver);
+	const struct i2c_device_id *match;
+	const void *data;
+
+	data = device_get_match_data(&client->dev);
+	if (!data) {
+		match = i2c_match_id(driver->id_table, client);
+		if (!match)
+			return NULL;
+
+		data = (const void *)match->driver_data;
+	}
+
+	return data;
+}
+EXPORT_SYMBOL(i2c_get_match_data);
+
 static int i2c_device_match(struct device *dev, struct device_driver *drv)
 {
 	struct i2c_client	*client = i2c_verify_client(dev);

include/linux/i2c.h

@@ -367,6 +367,8 @@ struct i2c_adapter *i2c_verify_adapter(struct device *dev);
 const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
 					 const struct i2c_client *client);
 
+const void *i2c_get_match_data(const struct i2c_client *client);
+
 static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
 {
 	struct device * const dev = kobj_to_dev(kobj);