/*      $NetBSD: com.c,v 1.1 2011/03/03 05:59:37 kiyohara Exp $ */

/*-
* Copyright (c) 2008 Izumi Tsutsui.  All rights reserved.
*
* 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.
*
* 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.
*/
/*-
* Copyright (c) 1993, 1994, 1995, 1996, 1997
*      Charles M. Hannum.  All rights reserved.
*
* Interrupt processing and hardware flow control partly based on code from
* Onno van der Linden and Gordon Ross.
*
* 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 Charles M. Hannum.
* 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.
*/

/*
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* 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. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
*
*      @(#)com.c       7.5 (Berkeley) 5/16/91
*/

#ifdef CONS_COM

#include <lib/libsa/stand.h>
#include <lib/libkern/libkern.h>

#include <dev/ic/comreg.h>

#include <machine/cpu.h>

#include "boot.h"
#include "ns16550.h"

#define CSR_READ(base, reg)             (*(volatile uint8_t *)((base) + (reg)))
#define CSR_WRITE(base, reg, val)                                       \
       do {                                                            \
               *(volatile uint8_t *)((base) + (reg)) = (val);          \
       } while (/* CONSTCOND */ 0)

#define COM_FREQ        1843200 /* 16-bit baud rate divisor */
#define COM_TOLERANCE   30      /* baud rate tolerance, in 0.1% units */

static int comspeed(long);

static int
comspeed(long speed)
{
#define divrnd(n, q)    (((n)*2/(q)+1)/2)       /* divide and round off */

       int x, err;
       long frequency = COM_FREQ * 10;

       if (speed <= 0)
               return -1;
       x = divrnd((frequency / 16), speed);
       if (x <= 0)
               return -1;
       err = divrnd(((quad_t)frequency) * 1000 / 16, speed * x) - 1000;
       if (err < 0)
               err = -err;
       if (err > COM_TOLERANCE)
               return -1;
       return x;

#undef  divrnd
}

void *
com_init(int addr, int speed)
{
       uint8_t *com_port;

       com_port = (void *)addr;

       CSR_WRITE(com_port, com_lctl, LCR_DLAB);
       speed = comspeed(speed);
       CSR_WRITE(com_port, com_dlbl, speed);
       CSR_WRITE(com_port, com_dlbh, speed >> 8);

       CSR_WRITE(com_port, com_lctl, LCR_PNONE | LCR_8BITS);
       CSR_WRITE(com_port, com_mcr, MCR_RTS | MCR_DTR);
       CSR_WRITE(com_port, com_fifo,
           FIFO_XMT_RST | FIFO_RCV_RST | FIFO_ENABLE);
       CSR_WRITE(com_port, com_ier, 0);

       return com_port;
}

void
com_putc(void *dev, int c)
{
       volatile uint8_t *com_port = dev;

       while ((CSR_READ(com_port, com_lsr) & LSR_TXRDY) == 0)
               ;

       CSR_WRITE(com_port, com_data, c);
}

int
com_getc(void *dev)
{
       volatile uint8_t *com_port = dev;

       while ((CSR_READ(com_port, com_lsr) & LSR_RXRDY) == 0)
               ;

       return CSR_READ(com_port, com_data);
}

int
com_scankbd(void *dev)
{
       volatile uint8_t *com_port = dev;

       if ((CSR_READ(com_port, com_lsr) & LSR_RXRDY) == 0)
               return -1;

       return CSR_READ(com_port, com_data);
}
#endif /* CONS_SERIAL */

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