power: qcom_smbb: Make an extcon for usb cable detection

On these PMICs the usb cable connection/disconnection is
indicated by the usb-valid interrupt being high or low
respectively. Let's make an extcon for that, so we can notify usb
drivers of the cable state.

Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/Kconfig

@@ -393,6 +393,7 @@ config CHARGER_QCOM_SMBB
 	tristate "Qualcomm Switch-Mode Battery Charger and Boost"
 	depends on MFD_SPMI_PMIC || COMPILE_TEST
 	depends on OF
+	depends on EXTCON
 	help
 	  Say Y to include support for the Switch-Mode Battery Charger and
 	  Boost (SMBB) hardware found in Qualcomm PM8941 PMICs.  The charger

drivers/power/qcom_smbb.c

@@ -34,6 +34,7 @@
 #include <linux/power_supply.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
+#include <linux/extcon.h>
 
 #define SMBB_CHG_VMAX		0x040
 #define SMBB_CHG_VSAFE		0x041
@@ -111,6 +112,7 @@ struct smbb_charger {
 	unsigned int revision;
 	unsigned int addr;
 	struct device *dev;
+	struct extcon_dev *edev;
 
 	bool dc_disabled;
 	bool jeita_ext_temp;
@@ -125,6 +127,11 @@ struct smbb_charger {
 	struct regmap *regmap;
 };
 
+static const unsigned int smbb_usb_extcon_cable[] = {
+	EXTCON_USB,
+	EXTCON_NONE,
+};
+
 static int smbb_vbat_weak_fn(unsigned int index)
 {
 	return 2100000 + index * 100000;
@@ -371,6 +378,8 @@ static irqreturn_t smbb_usb_valid_handler(int irq, void *_data)
 	struct smbb_charger *chg = _data;
 
 	smbb_set_line_flag(chg, irq, STATUS_USBIN_VALID);
+	extcon_set_cable_state_(chg->edev, EXTCON_USB,
+				chg->status & STATUS_USBIN_VALID);
 	power_supply_changed(chg->usb_psy);
 
 	return IRQ_HANDLED;
@@ -849,6 +858,18 @@ static int smbb_charger_probe(struct platform_device *pdev)
 		return PTR_ERR(chg->usb_psy);
 	}
 
+	chg->edev = devm_extcon_dev_allocate(&pdev->dev, smbb_usb_extcon_cable);
+	if (IS_ERR(chg->edev)) {
+		dev_err(&pdev->dev, "failed to allocate extcon device\n");
+		return -ENOMEM;
+	}
+
+	rc = devm_extcon_dev_register(&pdev->dev, chg->edev);
+	if (rc < 0) {
+		dev_err(&pdev->dev, "failed to register extcon device\n");
+		return rc;
+	}
+
 	if (!chg->dc_disabled) {
 		dc_cfg.drv_data = chg;
 		dc_cfg.supplied_to = smbb_bif;