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538 mauro 1 
/*
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 * Project: S.Ha.R.K.
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 *
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 * Coordinators:
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 *   Giorgio Buttazzo    <giorgio@sssup.it>
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 *   Paolo Gai           <pj@gandalf.sssup.it>
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 *
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 * Authors     :
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 *   Paolo Gai           <pj@gandalf.sssup.it>
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 *   Massimiliano Giorgi <massy@gandalf.sssup.it>
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 *   Luca Abeni          <luca@gandalf.sssup.it>
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 *   Tullio Facchinetti  <tullio.facchinetti@unipv.it>
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 *   (see the web pages for full authors list)
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 *
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 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
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 *
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 * http://www.sssup.it
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 * http://retis.sssup.it
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 * http://shark.sssup.it
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 */
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/*
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 * Copyright (C) 2000 Paolo Gai
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, write to the Free Software
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 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 *
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 */
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/* Serial communication device */
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/* This implementation is capable of handling 4 distinct COM ports */
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/* The COM port settings are the standard PC settings:             */
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/* PORT         ADDRESS         IRQ                                */
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/*   1           0x3F8           4                                 */
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/*   2           0x2F8           3                                 */
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/*   3           0x3E8           4                                 */
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/*   4           0x2E8           2                                 */
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/* By Massy
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 * I have modified the fast handler routines to support serial
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 * mouse better (see below)
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 */
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#include <kernel/kern.h>
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#include <drivers/scom.h>
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/* Base address for each standard COM link */
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static unsigned com_base[] = {0x03F8,0x02F8,0x03E8,0x02E8};
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/* Used for decoding the IIR status */
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const int IIRbits[] = {MS_CHANGED,TX_EMPTY,RX_FULL,LS_CHANGED};
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int serial_initialized[4] = {0, 0, 0, 0};
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/**
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 * Register level access functions.
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 */
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unsigned com_read(unsigned port, unsigned reg) {
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    unsigned b;
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    if (port > 3 || reg > 7 || (!serial_initialized[port])) return(0);
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    b = ll_in(com_base[port]+reg);
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    return(b);
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}
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void com_write(unsigned port, unsigned reg, unsigned value) {
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    if (port > 3 || reg > 7 || (!serial_initialized[port])) return;
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    ll_out(com_base[port]+reg,value);
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}
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/**
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 * Write the character "b" to the port "port".
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 * If wait is 0 then a busy port makes the fuction to return immediately.
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 * If wait is 1 loops until the port become free.
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 * Return 0 if the byte has been sent. Return 1 otherwise.
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 */
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unsigned com_send(unsigned port, BYTE b, unsigned wait) {
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    if (wait) {
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      while ((com_read(port,LSR) & 32) == 0);
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    } else {
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      if ((com_read(port,LSR) & 32) == 0) return(1);
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    }
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    com_write(port,THR,b);
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    return(0);
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}
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/**
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 * Read a character from the port "port".
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 * Polls the port until a character is ready to be read.
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 */
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unsigned com_receive(unsigned port) {
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    while ((com_read(port,LSR) & 1) == 0);
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    return(com_read(port,RBR));
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}
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/**
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 * Initialize a serial channel.
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 * Do not do anything if the port has been already initialized.
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 */
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int com_open(unsigned port,DWORD speed,BYTE parity,BYTE len,BYTE stop) {
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    unsigned long div,b_mask;
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    SYS_FLAGS f;        
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    f = kern_fsave();
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    if (serial_initialized[port]) {
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      kern_frestore(f);
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      return(0);
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    }
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    /* Now set up the serial link */
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    b_mask = (parity & 3) * 8 + ((stop - 1) & 1) * 4 + ((len - 5) & 3);
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    div = 115200L / speed;
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    /* Clear serial interrupt enable register */
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    com_write(port,IER,0);
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    /* Empty input buffer */
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    com_read(port,RBR);
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    /* Activate DLAB bit for speed setting */
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    com_write(port,LCR,0x80);
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    /* Load baud divisor */
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    com_write(port,0,div & 0x00FF);
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    div >>= 8;
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    com_write(port,1,div & 0x00FF);
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    /* Load control word (parity,stop bit,bit len) */
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    com_write(port,LCR,b_mask);
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    /* Attiva OUT1 & OUT2 */
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    com_write(port,MCR,0x0C);
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    serial_initialized[port] = 1;
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    kern_frestore(f);
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714 giacomo 143 
    return(0);
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}
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/**
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 * Close port channel & release the server.
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 */
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int com_close(unsigned port)
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{    
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    SYS_FLAGS f;
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    f = kern_fsave();
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    com_write(port,IER,0);
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    com_read(port,IIR);
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    com_read(port,RBR);
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    serial_initialized[port] = 0;
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    kern_frestore(f);
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    return(0);
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}
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