HelenOS sources

XHCI_LEGSUP_SEM_OS  423 uspace/drv/bus/usb/xhci/hc.c 	XHCI_REG_SET(hc->legsup, XHCI_LEGSUP_SEM_OS, 1);
XHCI_LEGSUP_SEM_OS  427 uspace/drv/bus/usb/xhci/hc.c 		    XHCI_REG_RD(hc->legsup, XHCI_LEGSUP_SEM_OS));
XHCI_LEGSUP_SEM_OS  429 uspace/drv/bus/usb/xhci/hc.c 			return XHCI_REG_RD(hc->legsup, XHCI_LEGSUP_SEM_OS) == 1 ? EOK : EIO;
HelenOS homepage, sources at GitHub