ns16550.c

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

/*	$Id: ns16550.c,v 1.3 2002/01/27 16:41:52 pefo Exp $ */

/*
 * Copyright (c) 2001 Opsycon AB  (www.opsycon.se)
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Opsycon AB.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */
#include <termio.h>
#include <machine/pio.h>
#include <machine/bus.h>
#include <dev/ns16550.h>

#include <pmon.h>

extern int getbaudval __P((int));

int ns16550 __P((int, char *, int, char));
extern int gt_uart __P((int, char *, int, int));

static int
nsinit (volatile ns16550dev *dp, int chan)
{
	int x;

    /* force access to id reg */
    outb(&dp->cfcr,0);
    outb(&dp->iir, 0);
    if ((inb(&dp->iir) & 0x38) != 0) {
	return 1;
    }

    /* in case it really is a 16550, enable the fifos */
    outb(&dp->fifo, FIFO_ENABLE);
    for(x = 0; x < 1000000; x++);
    outb(&dp->fifo, FIFO_ENABLE | FIFO_RCV_RST | FIFO_XMT_RST | FIFO_TRIGGER_1);
    for(x = 0; x < 1000000; x++);

    if (!((inb(&dp->iir) & IIR_FIFO_MASK) == IIR_FIFO_MASK))
	dp->fifo = 0;
    return 0;
}


static int
nsprogram (volatile ns16550dev *dp, int chan, int baudrate)
{
    unsigned short brtc;
    int timeout;

    /* wait for Tx fifo to completely drain */
    timeout = 10000;
    while (!(inb(&dp->lsr) & LSR_TSRE))
	if (--timeout == 0)
	    break;
    baudrate = getbaudval (baudrate);
    if (baudrate == 0)
      return 1;

    brtc = BRTC (baudrate);

    outb(&dp->cfcr, CFCR_DLAB);
    outb(&dp->data, brtc & 0xff);
    outb(&dp->ier, brtc >> 8);
    outb(&dp->cfcr, CFCR_8BITS);
    outb(&dp->mcr, MCR_DTR | MCR_RTS | MCR_IENABLE);
    outb(&dp->ier, 0);
    return 0;
}


int
ns16550 (int op, char *dat, int chan, char data)
{
    volatile ns16550dev *dp = (ns16550dev *) dat;

    if (chan > 0)
	return 1;

    switch (op) {
    case OP_INIT:
	return nsinit (dp, chan);

    case OP_XBAUD:
    case OP_BAUD:
	return nsprogram (dp, chan, data);

    case OP_TXRDY:
	return (inb(&dp->lsr) & LSR_TXRDY);

    case OP_TX:
	outb(&dp->data, data);
	break;

    case OP_RXRDY:
	return (inb(&dp->lsr) & LSR_RXRDY);

    case OP_RX:
	return inb(&dp->data) & 0xff;

    case OP_RXSTOP:
	if (data)
	    outb(&dp->mcr, inb(&dp->mcr) & ~MCR_RTS);	/* disable Rx */
	else
	    outb(&dp->mcr, inb(&dp->mcr) | MCR_RTS);	/* enable Rx */
	break;
    }
    return 0;
}