1/* 2 * Copyright (c) 1998 Robert Nordier 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are freely 6 * permitted provided that the above copyright notice and this 7 * paragraph and the following disclaimer are duplicated in all 8 * such forms. 9 * 10 * This software is provided "AS IS" and without any express or 11 * implied warranties, including, without limitation, the implied 12 * warranties of merchantability and fitness for a particular 13 * purpose. 14 * |
15 * $FreeBSD: head/sys/boot/i386/boot2/sio.S 129240 2004-05-14 20:29:30Z ru $ |
16 */ 17 |
18 .set SIO_PRT,SIOPRT # Base port 19 .set SIO_FMT,SIOFMT # 8N1 20 .set SIO_DIV,(115200/SIOSPD) # 115200 / SPD |
21 22 .globl sio_init 23 .globl sio_flush 24 .globl sio_putc 25 .globl sio_getc 26 .globl sio_ischar 27 28/* void sio_init(void) */ 29 |
30sio_init: movw $SIO_PRT+0x3,%dx # Data format reg 31 movb $SIO_FMT|0x80,%al # Set format 32 outb %al,(%dx) # and DLAB 33 pushl %edx # Save 34 subb $0x3,%dl # Divisor latch reg 35 movw $SIO_DIV,%ax # Set 36 outw %ax,(%dx) # BPS 37 popl %edx # Restore 38 movb $SIO_FMT,%al # Clear 39 outb %al,(%dx) # DLAB 40 incl %edx # Modem control reg 41 movb $0x3,%al # Set RTS, 42 outb %al,(%dx) # DTR 43 incl %edx # Line status reg |
44 45/* void sio_flush(void) */ 46 |
47sio_flush.0: call sio_getc.1 # Get character 48sio_flush: call sio_ischar # Check for character 49 jnz sio_flush.0 # Till none 50 ret # To caller |
51 52/* void sio_putc(int c) */ 53 |
54sio_putc: movw $SIO_PRT+0x5,%dx # Line status reg 55 xor %ecx,%ecx # Timeout 56 movb $0x40,%ch # counter 57sio_putc.1: inb (%dx),%al # Transmitter 58 testb $0x20,%al # buffer empty? 59 loopz sio_putc.1 # No 60 jz sio_putc.2 # If timeout 61 movb 0x4(%esp,1),%al # Get character 62 subb $0x5,%dl # Transmitter hold reg 63 outb %al,(%dx) # Write character 64sio_putc.2: ret $0x4 # To caller |
65 66/* int sio_getc(void) */ 67 |
68sio_getc: call sio_ischar # Character available? 69 jz sio_getc # No 70sio_getc.1: subb $0x5,%dl # Receiver buffer reg 71 inb (%dx),%al # Read character 72 ret # To caller |
73 74/* int sio_ischar(void) */ 75 |
76sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register 77 xorl %eax,%eax # Zero 78 inb (%dx),%al # Received data 79 andb $0x1,%al # ready? 80 ret # To caller |