How to enable OTG using Kernel 6.15

I’ve got my Zero 3W booting with Kernel 6.15 and everything working except for OTG.

Does anyone know how to enable OTG? I’m assuming using an overlay, but in the official distro we have this …
&usbdrd_dwc3 {
dr_mode = “otg”;
};

It doesn’t look like the official kernel has usbdrd_dwc3 in the DTB.