regulator: max8973: initial DT support

This patch adds primitive DT support to the max8973 regulator driver. None
of the configuration parameters, supported in the platform data are yet
available in DT, therefore no configuration is performed if booting with
no platform data. This means, that DT instantiation can only be used on
boards, where no run-time configuration of the chip is required. In such
cases the driver can be used to scale its output voltage. In the future
support for configuration parameters should be added.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/regulator/max8973-regulator.txt

@@ -0,0 +1,21 @@
+* Maxim MAX8973 Voltage Regulator
+
+Required properties:
+
+- compatible:	must be "maxium,max8973"
+- reg:		the i2c slave address of the regulator. It should be 0x1b.
+
+Any standard regulator properties can be used to configure the single max8973
+DCDC.
+
+Example:
+
+	max8973@1b {
+		compatible = "maxium,max8973";
+		reg = <0x1b>;
+
+		regulator-min-microvolt = <935000>;
+		regulator-max-microvolt = <1200000>;
+		regulator-boot-on;
+		regulator-always-on;
+	};

drivers/regulator/max8973-regulator.c

@@ -26,10 +26,12 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/err.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 #include <linux/regulator/max8973-regulator.h>
+#include <linux/regulator/of_regulator.h>
 #include <linux/gpio.h>
 #include <linux/i2c.h>
 #include <linux/slab.h>
@@ -370,7 +372,8 @@ static int max8973_probe(struct i2c_client *client,
 	int ret;
 
 	pdata = client->dev.platform_data;
-	if (!pdata) {
+
+	if (!pdata && !client->dev.of_node) {
 		dev_err(&client->dev, "No Platform data");
 		return -EIO;
 	}
@@ -400,20 +403,25 @@ static int max8973_probe(struct i2c_client *client,
 	max->desc.uV_step = MAX8973_VOLATGE_STEP;
 	max->desc.n_voltages = MAX8973_BUCK_N_VOLTAGE;
 
-	if (!pdata->enable_ext_control) {
+	if (!pdata || !pdata->enable_ext_control) {
 		max->desc.enable_reg = MAX8973_VOUT;
 		max->desc.enable_mask = MAX8973_VOUT_ENABLE;
 		max->ops.enable = regulator_enable_regmap;
 		max->ops.disable = regulator_disable_regmap;
 		max->ops.is_enabled = regulator_is_enabled_regmap;
 	}
 
-	max->enable_external_control = pdata->enable_ext_control;
-	max->dvs_gpio = pdata->dvs_gpio;
-	max->curr_gpio_val = pdata->dvs_def_state;
-	max->curr_vout_reg = MAX8973_VOUT + pdata->dvs_def_state;
+	if (pdata) {
+		max->dvs_gpio = pdata->dvs_gpio;
+		max->enable_external_control = pdata->enable_ext_control;
+		max->curr_gpio_val = pdata->dvs_def_state;
+		max->curr_vout_reg = MAX8973_VOUT + pdata->dvs_def_state;
+	} else {
+		max->dvs_gpio = -EINVAL;
+		max->curr_vout_reg = MAX8973_VOUT;
+	}
+
 	max->lru_index[0] = max->curr_vout_reg;
-	max->valid_dvs_gpio = false;
 
 	if (gpio_is_valid(max->dvs_gpio)) {
 		int gpio_flags;
@@ -439,16 +447,21 @@ static int max8973_probe(struct i2c_client *client,
 			max->lru_index[i] = i;
 		max->lru_index[0] = max->curr_vout_reg;
 		max->lru_index[max->curr_vout_reg] = 0;
+	} else {
+		max->valid_dvs_gpio = false;
 	}
 
-	ret = max8973_init_dcdc(max, pdata);
-	if (ret < 0) {
-		dev_err(max->dev, "Max8973 Init failed, err = %d\n", ret);
-		return ret;
+	if (pdata) {
+		ret = max8973_init_dcdc(max, pdata);
+		if (ret < 0) {
+			dev_err(max->dev, "Max8973 Init failed, err = %d\n", ret);
+			return ret;
+		}
 	}
 
 	config.dev = &client->dev;
-	config.init_data = pdata->reg_init_data;
+	config.init_data = pdata ? pdata->reg_init_data :
+		of_get_regulator_init_data(&client->dev, client->dev.of_node);
 	config.driver_data = max;
 	config.of_node = client->dev.of_node;
 	config.regmap = max->regmap;