extcon: intel-cht-wc: Enable external charger

In some configuration external charger "#charge enable" signal is
connected to PMIC. Enable it at device probing to allow charging.

Save CHGRCTRL0 and CHGDISCTR registers at driver probing and restore
them at driver unbind to re-enable hardware charging control if it was
enabled before.

Tested at Lenovo Yoga Book (YB1-X91L).
Signed-off-by: Yauhen Kharuzhy <jekhor@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

drivers/extcon/extcon-intel-cht-wc.c

@@ -56,6 +56,13 @@
 #define CHT_WC_USBSRC_TYPE_OTHER	8
 #define CHT_WC_USBSRC_TYPE_DCP_EXTPHY	9
 
+#define CHT_WC_CHGDISCTRL		0x5e2f
+#define CHT_WC_CHGDISCTRL_OUT		BIT(0)
+/* 0 - open drain, 1 - regular push-pull output */
+#define CHT_WC_CHGDISCTRL_DRV		BIT(4)
+/* 0 - pin is controlled by SW, 1 - by HW */
+#define CHT_WC_CHGDISCTRL_FN		BIT(6)
+
 #define CHT_WC_PWRSRC_IRQ		0x6e03
 #define CHT_WC_PWRSRC_IRQ_MASK		0x6e0f
 #define CHT_WC_PWRSRC_STS		0x6e1e
@@ -218,6 +225,18 @@ static void cht_wc_extcon_set_otgmode(struct cht_wc_extcon_data *ext,
 		dev_err(ext->dev, "Error updating CHGRCTRL1 reg: %d\n", ret);
 }
 
+static void cht_wc_extcon_enable_charging(struct cht_wc_extcon_data *ext,
+					  bool enable)
+{
+	unsigned int val = enable ? 0 : CHT_WC_CHGDISCTRL_OUT;
+	int ret;
+
+	ret = regmap_update_bits(ext->regmap, CHT_WC_CHGDISCTRL,
+				 CHT_WC_CHGDISCTRL_OUT, val);
+	if (ret)
+		dev_err(ext->dev, "Error updating CHGDISCTRL reg: %d\n", ret);
+}
+
 /* Small helper to sync EXTCON_CHG_USB_SDP and EXTCON_USB state */
 static void cht_wc_extcon_set_state(struct cht_wc_extcon_data *ext,
 				    unsigned int cable, bool state)
@@ -242,6 +261,7 @@ static void cht_wc_extcon_pwrsrc_event(struct cht_wc_extcon_data *ext)
 
 	id = cht_wc_extcon_get_id(ext, pwrsrc_sts);
 	if (id == USB_ID_GND) {
+		cht_wc_extcon_enable_charging(ext, false);
 		cht_wc_extcon_set_otgmode(ext, true);
 
 		/* The 5v boost causes a false VBUS / SDP detect, skip */
@@ -249,6 +269,7 @@ static void cht_wc_extcon_pwrsrc_event(struct cht_wc_extcon_data *ext)
 	}
 
 	cht_wc_extcon_set_otgmode(ext, false);
+	cht_wc_extcon_enable_charging(ext, true);
 
 	/* Plugged into a host/charger or not connected? */
 	if (!(pwrsrc_sts & CHT_WC_PWRSRC_VBUS)) {
@@ -302,6 +323,14 @@ static int cht_wc_extcon_sw_control(struct cht_wc_extcon_data *ext, bool enable)
 {
 	int ret, mask, val;
 
+	val = enable ? 0 : CHT_WC_CHGDISCTRL_FN;
+	ret = regmap_update_bits(ext->regmap, CHT_WC_CHGDISCTRL,
+				 CHT_WC_CHGDISCTRL_FN, val);
+	if (ret)
+		dev_err(ext->dev,
+			"Error setting sw control for CHGDIS pin: %d\n",
+			ret);
+
 	mask = CHT_WC_CHGRCTRL0_SWCONTROL | CHT_WC_CHGRCTRL0_CCSM_OFF;
 	val = enable ? mask : 0;
 	ret = regmap_update_bits(ext->regmap, CHT_WC_CHGRCTRL0, mask, val);
@@ -353,7 +382,10 @@ static int cht_wc_extcon_probe(struct platform_device *pdev)
 	/* Enable sw control */
 	ret = cht_wc_extcon_sw_control(ext, true);
 	if (ret)
-		return ret;
+		goto disable_sw_control;
+
+	/* Disable charging by external battery charger */
+	cht_wc_extcon_enable_charging(ext, false);
 
 	/* Register extcon device */
 	ret = devm_extcon_dev_register(ext->dev, ext->edev);