लिनक्स/linux-0.01.tar/kernel/serial.c
< लिनक्स | linux-0.01.tar
/*
* 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();
}