extcon: int3496: Add support for controlling Vbus through a regulator

On some boards the 5V vboost-regulator for powering devices connected to
the micro USB connector is not controlled through a GPIO. This happens
for example when the 5V vboost-regulator is integrated into the charger IC
and controlled over I2C.

Add support for controlling the 5V vboost-regulator through the regulator
framework for such boards.

Signed-off-by: Hans de Goede <[e-mail]>
Signed-off-by: Chanwoo Choi <[e-mail]>

drivers/extcon/extcon-intel-int3496.c

···
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
 
 #define INT3496_GPIO_USB_ID	0
 #define INT3496_GPIO_VBUS_EN	1
···
 	struct gpio_desc *gpio_usb_id;
 	struct gpio_desc *gpio_vbus_en;
 	struct gpio_desc *gpio_usb_mux;
+	struct regulator *vbus_boost;
 	int usb_id_irq;
+	bool vbus_boost_enabled;
 };
 
 static const unsigned int int3496_cable[] = {
···
 	{ },
 };
 
+static void int3496_set_vbus_boost(struct int3496_data *data, bool enable)
+{
+	int ret;
+
+	if (IS_ERR_OR_NULL(data->vbus_boost))
+		return;
+
+	if (data->vbus_boost_enabled == enable)
+		return;
+
+	if (enable)
+		ret = regulator_enable(data->vbus_boost);
+	else
+		ret = regulator_disable(data->vbus_boost);
+
+	if (ret == 0)
+		data->vbus_boost_enabled = enable;
+	else
+		dev_err(data->dev, "Error updating Vbus boost regulator: %d\n", ret);
+}
+
 static void int3496_do_usb_id(struct work_struct *work)
 {
 	struct int3496_data *data =
···
 
 	if (!IS_ERR(data->gpio_vbus_en))
 		gpiod_direction_output(data->gpio_vbus_en, !id);
+	else
+		int3496_set_vbus_boost(data, !id);
 
 	extcon_set_state_sync(data->edev, EXTCON_USB_HOST, !id);
 }
···
 	}
 
 	data->gpio_vbus_en = devm_gpiod_get(dev, "vbus", GPIOD_ASIS);
-	if (IS_ERR(data->gpio_vbus_en))
+	if (IS_ERR(data->gpio_vbus_en)) {
 		dev_dbg(dev, "can't request VBUS EN GPIO\n");
+		data->vbus_boost = devm_regulator_get_optional(dev, "vbus");
+	}
 
 	data->gpio_usb_mux = devm_gpiod_get(dev, "mux", GPIOD_ASIS);
 	if (IS_ERR(data->gpio_usb_mux))