HelenOS sources

XHCI_CAP_MAX_SLOTS   69 uspace/drv/bus/usb/xhci/debug.c 	DUMP_REG(cap, XHCI_CAP_MAX_SLOTS);
XHCI_CAP_MAX_SLOTS  229 uspace/drv/bus/usb/xhci/hc.c 	hc->max_slots = XHCI_REG_RD(hc->cap_regs, XHCI_CAP_MAX_SLOTS);
HelenOS homepage, sources at GitHub