.TH UARTP8250 9
.SH NAME
uartp8250 \- portable 8250-style uarts
.SH SYNOPSIS
.EX
#include "../port/uartp8250.h"

typedef struct Ctlr Ctlr;
struct Ctlr {
	void	*reg;
	uint	(*get)(void*, int);
	void	(*set)(void*, int, uint);
	int	(*itr)(Uart*, int);

	int	irq;
	int	tbdf;
	int	iena;

	uchar	sticky[8];

	Lock;
	int	hasfifo;
	int	checkfifo;
	int	fena;
};
.EE
.PP
.ta \w'\fLPhysUart 'u
.PP
.B
PhysUart		p8250physuart;
.PP
.B
void	i8250interrupt(Ureg*, void*);
.SH DESCRIPTION
P8250 provides a portable interface for 8250-style uarts.
All necessary functions are provided except for 
.BR get ,
.BR set ,
and
.BR itr .
These functions get or set an 8250 register or enable
or disable the interrupt, respectively.  Since the
.B PhysUart
structure is required for device discovery, a dummy
version needs to be provided
.IP
.EX
PhysUart myphysuart = {
	.name		= "myuart",
	.pnp		= mypnp,
};
.EE
.PP
On entry of the pnp function, the
.B PhysUart
can be filled out:
.EX
	memmove(&myphysuart, &p8250physuart, sizeof(PhysUart));
	myphysuart.name = "myuart";
	myphysuart.pnp = mypnp;
.EE
.PP
as can the
.B Ctlr
structure, which is assigned to
.BR "uart->regs" .
.SH SOURCE
.B /sys/src/9/port/uartp8250.h
.br
.B /sys/src/9/port/uartp8250.c
.SH "SEE ALSO"
.IR uart (3).
.SH BUGS
The
.B PhysUart
is uncomfortable to use for device discovery.