serial.c

开发三星s3c44b0引导程序

/*
 * (C) Copyright 2002
 * Lineo, Inc <www.lineo.com>
 * Bernhard Kuhn <[e-mail]>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Marius Groeger <[e-mail]>
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Alex Zuepke <[e-mail]>
 *
 * Copyright (C) 1999 2000 2001 Erik Mouw ([e-mail])
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <zooboot.h>
#include <hardware.h>

static usart_t *us=USARTB_BASE;

#define USART_CLK (CFG_HZ * 128)

void serial_setbrg(bd_t *bd, int baudrate) {
   us->brgr = baudrate ? (USART_CLK + 8 * baudrate)/(16 * baudrate) : 0;
};

void serial_init(bd_t *bd) {
  const char *baudrate;

  if ((baudrate = getenv(bd, "baudrate")) != 0)
    bd->bi_baudrate = simple_strtoul(baudrate, NULL, 10);
  
  serial_setbrg(bd, bd->bi_baudrate);

  us->cr=( RSTRX | RSTTX );
  us->cr=( RXEN | TXEN );
  us->mr=( USCLKS_ACLK | CHRL_EIGHT | PAR_NONE | NBSTOP_1 );
  us->imr=~0ul;
};

void serial_putc(const char c) {
  if(c == '\n') serial_putc('\r');
  while( (us->csr & TXRDY) == 0 );
  us->thr=c;
};

int serial_getc() {
  while( (us->csr & RXRDY) == 0 );
  return us->rhr & 0xff;
};

int serial_tstc(void) {
  return ((us->csr & RXRDY) == RXRDY);
};