HelenOS sources

XHCI_OP_EWE       160 uspace/drv/bus/usb/xhci/debug.c 	DUMP_REG(hc->op_regs, XHCI_OP_EWE);
XHCI_OP_EWE       485 uspace/drv/bus/usb/xhci/hc.c 	XHCI_REG_SET(hc->op_regs, XHCI_OP_EWE, 1);
HelenOS homepage, sources at GitHub