ref: 2b40407e8c45d3a183bb04748f16f6589c68b0fc
dir: /sys/src/9/lx2k/io.h/
enum {
	IRQfiq		= -1,
	PPI		= 16,
	SPI		= 32,
	IRQcntps	= PPI+13,
	IRQcntpns	= PPI+14,
	IRQuart		= SPI+32,
	IRQusb1		= SPI+80,
	IRQusb2		= SPI+81,
	IRQpci3		= SPI+119,
	IRQpci5		= SPI+129,
};
#define BUSUNKNOWN (-1)
#define PCIWINDOW	0
#define	PCIWADDR(x)	(PADDR(x)+PCIWINDOW)