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