usb: typec: tcpci_maxim: Enable VSAFE0V signalling

Unmask EXTENDED_STATUS_MASK.vSafe0V, ALERT.Extended_Status
and set vbus_vsafe0v to enable VSAFE0V signalling.
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20201202040840.663578-3-badhri@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpci_maxim.c

@@ -112,11 +112,18 @@ static void max_tcpci_init_regs(struct max_tcpci_chip *chip)
 		return;
 	}
 
+	/* Enable VSAFE0V detection */
+	ret = max_tcpci_write8(chip, TCPC_EXTENDED_STATUS_MASK, TCPC_EXTENDED_STATUS_VSAFE0V);
+	if (ret < 0) {
+		dev_err(chip->dev, "Unable to unmask TCPC_EXTENDED_STATUS_VSAFE0V ret:%d\n", ret);
+		return;
+	}
+
 	alert_mask = TCPC_ALERT_TX_SUCCESS | TCPC_ALERT_TX_DISCARDED | TCPC_ALERT_TX_FAILED |
 		TCPC_ALERT_RX_HARD_RST | TCPC_ALERT_RX_STATUS | TCPC_ALERT_CC_STATUS |
 		TCPC_ALERT_VBUS_DISCNCT | TCPC_ALERT_RX_BUF_OVF | TCPC_ALERT_POWER_STATUS |
 		/* Enable Extended alert for detecting Fast Role Swap Signal */
-		TCPC_ALERT_EXTND;
+		TCPC_ALERT_EXTND | TCPC_ALERT_EXTENDED_STATUS;
 
 	ret = max_tcpci_write16(chip, TCPC_ALERT_MASK, alert_mask);
 	if (ret < 0) {
@@ -315,6 +322,12 @@ static irqreturn_t _max_tcpci_irq(struct max_tcpci_chip *chip, u16 status)
 		}
 	}
 
+	if (status & TCPC_ALERT_EXTENDED_STATUS) {
+		ret = max_tcpci_read8(chip, TCPC_EXTENDED_STATUS, (u8 *)&reg_status);
+		if (ret >= 0 && (reg_status & TCPC_EXTENDED_STATUS_VSAFE0V))
+			tcpm_vbus_change(chip->port);
+	}
+
 	if (status & TCPC_ALERT_RX_STATUS)
 		process_rx(chip, status);
 
@@ -442,6 +455,7 @@ static int max_tcpci_probe(struct i2c_client *client, const struct i2c_device_id
 	chip->data.init = tcpci_init;
 	chip->data.frs_sourcing_vbus = max_tcpci_frs_sourcing_vbus;
 	chip->data.auto_discharge_disconnect = true;
+	chip->data.vbus_vsafe0v = true;
 
 	max_tcpci_init_regs(chip);
 	chip->tcpci = tcpci_register_port(chip->dev, &chip->data);