phy: tegra: xusb: Add support to get companion USB 3 port

Tegra XUSB host, device mode driver requires the USB 3 companion port
number for corresponding USB 2 port. Add API to retrieve the same.

Signed-off-by: Nagarjuna Kristam <nkristam@nvidia.com>
Reviewed-by: JC Kuo <jckuo@nvidia.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/phy/tegra/xusb.c

@@ -1299,6 +1299,27 @@ int tegra_phy_xusb_utmi_port_reset(struct phy *phy)
 }
 EXPORT_SYMBOL_GPL(tegra_phy_xusb_utmi_port_reset);
 
+int tegra_xusb_padctl_get_usb3_companion(struct tegra_xusb_padctl *padctl,
+				    unsigned int port)
+{
+	struct tegra_xusb_usb2_port *usb2;
+	struct tegra_xusb_usb3_port *usb3;
+	int i;
+
+	usb2 = tegra_xusb_find_usb2_port(padctl, port);
+	if (!usb2)
+		return -EINVAL;
+
+	for (i = 0; i < padctl->soc->ports.usb3.count; i++) {
+		usb3 = tegra_xusb_find_usb3_port(padctl, i);
+		if (usb3 && usb3->port == usb2->base.index)
+			return usb3->base.index;
+	}
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(tegra_xusb_padctl_get_usb3_companion);
+
 MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
 MODULE_DESCRIPTION("Tegra XUSB Pad Controller driver");
 MODULE_LICENSE("GPL v2");