HelenOS sources

XHCI_EC_SP_MINOR  333 uspace/drv/bus/usb/xhci/debug.c 		    XHCI_REG_RD(ec, XHCI_EC_SP_MINOR),
XHCI_EC_SP_MINOR   99 uspace/drv/bus/usb/xhci/hc.c 			minor = XHCI_REG_RD(ec, XHCI_EC_SP_MINOR);
HelenOS homepage, sources at GitHub