power: supply: bq24190_charger: add extcon support for USB OTG

Add extcon support so that we can notify USB drivers of cable state
changes. Based on work from Jonathan Marek. USB OTG was tested on a LG
Nexus 5 (hammerhead) phone.
Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/bq24190_charger.c

@@ -21,6 +21,7 @@
 #include <linux/workqueue.h>
 #include <linux/gpio.h>
 #include <linux/i2c.h>
+#include <linux/extcon-provider.h>
 
 #define	BQ24190_MANUFACTURER	"Texas Instruments"
 
@@ -159,6 +160,7 @@
 struct bq24190_dev_info {
 	struct i2c_client		*client;
 	struct device			*dev;
+	struct extcon_dev		*edev;
 	struct power_supply		*charger;
 	struct power_supply		*battery;
 	struct delayed_work		input_current_limit_work;
@@ -174,6 +176,11 @@ struct bq24190_dev_info {
 	u8				watchdog;
 };
 
+static const unsigned int bq24190_usb_extcon_cable[] = {
+	EXTCON_USB,
+	EXTCON_NONE,
+};
+
 /*
  * The tables below provide a 2-way mapping for the value that goes in
  * the register field and the real-world value that it represents.
@@ -1528,6 +1535,20 @@ static const struct power_supply_desc bq24190_battery_desc = {
 	.property_is_writeable	= bq24190_battery_property_is_writeable,
 };
 
+static int bq24190_configure_usb_otg(struct bq24190_dev_info *bdi, u8 ss_reg)
+{
+	bool otg_enabled;
+	int ret;
+
+	otg_enabled = !!(ss_reg & BQ24190_REG_SS_VBUS_STAT_MASK);
+	ret = extcon_set_state_sync(bdi->edev, EXTCON_USB, otg_enabled);
+	if (ret < 0)
+		dev_err(bdi->dev, "Can't set extcon state to %d: %d\n",
+			otg_enabled, ret);
+
+	return ret;
+}
+
 static void bq24190_check_status(struct bq24190_dev_info *bdi)
 {
 	const u8 battery_mask_ss = BQ24190_REG_SS_CHRG_STAT_MASK;
@@ -1597,8 +1618,10 @@ static void bq24190_check_status(struct bq24190_dev_info *bdi)
 		bdi->ss_reg = ss_reg;
 	}
 
-	if (alert_charger || alert_battery)
+	if (alert_charger || alert_battery) {
 		power_supply_changed(bdi->charger);
+		bq24190_configure_usb_otg(bdi, ss_reg);
+	}
 	if (alert_battery && bdi->battery)
 		power_supply_changed(bdi->battery);
 
@@ -1732,6 +1755,14 @@ static int bq24190_probe(struct i2c_client *client,
 		return -EINVAL;
 	}
 
+	bdi->edev = devm_extcon_dev_allocate(dev, bq24190_usb_extcon_cable);
+	if (IS_ERR(bdi->edev))
+		return PTR_ERR(bdi->edev);
+
+	ret = devm_extcon_dev_register(dev, bdi->edev);
+	if (ret < 0)
+		return ret;
+
 	pm_runtime_enable(dev);
 	pm_runtime_use_autosuspend(dev);
 	pm_runtime_set_autosuspend_delay(dev, 600);
@@ -1778,6 +1809,10 @@ static int bq24190_probe(struct i2c_client *client,
 		goto out_charger;
 	}
 
+	ret = bq24190_configure_usb_otg(bdi, bdi->ss_reg);
+	if (ret < 0)
+		goto out_charger;
+
 	ret = bq24190_sysfs_create_group(bdi);
 	if (ret < 0) {
 		dev_err(dev, "Can't create sysfs entries\n");