9f61746f5a
sio.S. This is not particularly needed for head right now, but it is intended to merge to stable/9, to fix boot2 build with clang there. Reviewed by: avg MFC after: 3 days
85 lines
2.2 KiB
ArmAsm
85 lines
2.2 KiB
ArmAsm
/*
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* Copyright (c) 1998 Robert Nordier
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are freely
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* permitted provided that the above copyright notice and this
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* paragraph and the following disclaimer are duplicated in all
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* such forms.
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*
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* This software is provided "AS IS" and without any express or
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* implied warranties, including, without limitation, the implied
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* warranties of merchantability and fitness for a particular
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* purpose.
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*
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* $FreeBSD$
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*/
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.set SIO_PRT,SIOPRT # Base port
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.set SIO_FMT,SIOFMT # 8N1
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.globl sio_init
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.globl sio_flush
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.globl sio_putc
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.globl sio_getc
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.globl sio_ischar
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/* int sio_init(int div) */
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sio_init: pushl %eax
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movw $SIO_PRT+0x3,%dx # Data format reg
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movb $SIO_FMT|0x80,%al # Set format
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outb %al,(%dx) # and DLAB
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subb $0x3,%dl # Divisor latch reg
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popl %eax
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outw %ax,(%dx) # BPS
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movw $SIO_PRT+0x3,%dx # Data format reg
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movb $SIO_FMT,%al # Clear
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outb %al,(%dx) # DLAB
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incl %edx # Modem control reg
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movb $0x3,%al # Set RTS,
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outb %al,(%dx) # DTR
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incl %edx # Line status reg
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# Fallthrough
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/* int sio_flush(void) */
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sio_flush: xorl %ecx,%ecx # Timeout
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movb $0x80,%ch # counter
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sio_flush.1: call sio_ischar # Check for character
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jz sio_flush.2 # Till none
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loop sio_flush.1 # or counter is zero
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movb $1, %al # Exhausted all tries
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sio_flush.2: ret # To caller
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/* void sio_putc(int c) */
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sio_putc: pushl %eax
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movw $SIO_PRT+0x5,%dx # Line status reg
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xor %ecx,%ecx # Timeout
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movb $0x40,%ch # counter
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sio_putc.1: inb (%dx),%al # Transmitter
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testb $0x20,%al # buffer empty?
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loopz sio_putc.1 # No
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jz sio_putc.2 # If timeout
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popl %eax # Get the character
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subb $0x5,%dl # Transmitter hold reg
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outb %al,(%dx) # Write character
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sio_putc.2: ret # To caller
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/* int sio_getc(void) */
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sio_getc: call sio_ischar # Character available?
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jz sio_getc # No
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sio_getc.1: subb $0x5,%dl # Receiver buffer reg
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inb (%dx),%al # Read character
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ret # To caller
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/* int sio_ischar(void) */
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sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register
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xorl %eax,%eax # Zero
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inb (%dx),%al # Received data
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andb $0x1,%al # ready?
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ret # To caller
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