[PATCH v1 2/2] usb: typec: mux: tusb1046: support HPD_IN override

[Ajit Singh <blfizzyy@gmail.com>]

For boards where HPD_IN is not asserted by hardware, software can
force it high over I2C using the HPDIN_OVERRIDE bit in the General
register (0x0A).

Add support for the optional ti,hpd-in-override property to force
HPD_IN high when DisplayPort mode is selected. Clear the override
when switching to USB or Safe mode, and preserve the existing
bit value when the property is absent.

Signed-off-by: Ajit Singh <blfizzyy@gmail.com>
---
 drivers/usb/typec/mux/tusb1046.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/usb/typec/mux/tusb1046.c b/drivers/usb/typec/mux/tusb1046.c
index 34ef81f75693..c21b1f8b9786 100644
--- a/drivers/usb/typec/mux/tusb1046.c
+++ b/drivers/usb/typec/mux/tusb1046.c
@@ -21,6 +21,7 @@
 /* General register bits */
 #define TUSB1046_GENERAL_FLIPSEL BIT(2)
 #define TUSB1046_GENERAL_CTLSEL  GENMASK(1, 0)
+#define TUSB1046_GENERAL_HPDIN_OVERRIDE BIT(3)
 
 /* Mux modes */
 #define TUSB1046_CTLSEL_DISABLED          0x0
@@ -32,6 +33,7 @@ struct tusb1046_priv {
 	struct i2c_client *client;
 	struct typec_switch_dev *sw;
 	struct typec_mux_dev *mux;
+	bool hpdin_override;
 
 	/* Lock General register during accesses */
 	struct mutex general_reg_lock;
@@ -44,6 +46,7 @@ static int tusb1046_mux_set(struct typec_mux_dev *mux,
 	struct i2c_client *client = priv->client;
 	struct device *dev = &client->dev;
 	int mode, val, ret = 0;
+	bool dp_active = false;
 
 	if (state->mode >= TYPEC_STATE_MODAL &&
 	    state->alt->svid != USB_TYPEC_DP_SID)
@@ -67,9 +70,11 @@ static int tusb1046_mux_set(struct typec_mux_dev *mux,
 	case TYPEC_DP_STATE_C:
 	case TYPEC_DP_STATE_E:
 		mode = TUSB1046_CTLSEL_4LANE_DP;
+		dp_active = true;
 		break;
 	case TYPEC_DP_STATE_D:
 		mode = TUSB1046_CTLSEL_USB3_AND_2LANE_DP;
+		dp_active = true;
 		break;
 	case TYPEC_STATE_SAFE:
 	default:
@@ -80,6 +85,13 @@ static int tusb1046_mux_set(struct typec_mux_dev *mux,
 	val &= ~TUSB1046_GENERAL_CTLSEL;
 	val |= mode;
 
+	if (priv->hpdin_override) {
+		if (dp_active)
+			val |= TUSB1046_GENERAL_HPDIN_OVERRIDE;
+		else
+			val &= ~TUSB1046_GENERAL_HPDIN_OVERRIDE;
+	}
+
 	ret = i2c_smbus_write_byte_data(client, TUSB1046_REG_GENERAL, val);
 
 out_unlock:
@@ -131,6 +143,8 @@ static int tusb1046_i2c_probe(struct i2c_client *client)
 		return -ENOMEM;
 
 	priv->client = client;
+	priv->hpdin_override =
+		device_property_read_bool(dev, "ti,hpd-in-override");
 
 	mutex_init(&priv->general_reg_lock);
 
-- 
2.50.1 (Apple Git-155)