/* *  linux/kernel/serial.c * *  (C) 1991  Linus Torvalds *//* *	serial.c * * This module implements the rs232 io functions *	void rs_write(struct tty_struct * queue); *	void rs_init(void); * and all interrupts pertaining to serial IO. */#include <linux/tty.h>#include <linux/sched.h>#include <asm/system.h>#include <asm/io.h>#define WAKEUP_CHARS (TTY_BUF_SIZE/4)extern void rs1_interrupt(void);extern void rs2_interrupt(void);static void init(int port){	outb_p(0x80,port+3);	/* set DLAB of line control reg */	outb_p(0x30,port);	/* LS of divisor (48 -> 2400 bps */	outb_p(0x00,port+1);	/* MS of divisor */	outb_p(0x03,port+3);	/* reset DLAB */	outb_p(0x0b,port+4);	/* set DTR,RTS, OUT_2 */	outb_p(0x0d,port+1);	/* enable all intrs but writes */	(void)inb(port);	/* read data port to reset things (?) */}void rs_init(void){	set_intr_gate(0x24,rs1_interrupt);	set_intr_gate(0x23,rs2_interrupt);	init(tty_table[1].read_q.data);	init(tty_table[2].read_q.data);	outb(inb_p(0x21)&0xE7,0x21);}/* * This routine gets called when tty_write has put something into * the write_queue. It must check wheter the queue is empty, and * set the interrupt register accordingly * *	void _rs_write(struct tty_struct * tty); */void rs_write(struct tty_struct * tty){	cli();	if (!EMPTY(tty->write_q))		outb(inb_p(tty->write_q.data+1)|0x02,tty->write_q.data+1);	sti();}