arch/mips/au1000/common/puts.c

   1 /*
   2  *
   3  * BRIEF MODULE DESCRIPTION
   4  *      Low level uart routines to directly access a 16550 uart.
   5  *
   6  * Copyright 2001 MontaVista Software Inc.
   7  * Author: MontaVista Software, Inc.
   8  *              ppopov@mvista.com or source@mvista.com
   9  *
  10  *  This program is free software; you can redistribute  it and/or modify it
  11  *  under  the terms of  the GNU General  Public License as published by the
  12  *  Free Software Foundation;  either version 2 of the  License, or (at your
  13  *  option) any later version.
  14  *
  15  *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
  16  *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
  17  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
  18  *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
  19  *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
  21  *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  22  *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
  23  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  *
  26  *  You should have received a copy of the  GNU General Public License along
  27  *  with this program; if not, write  to the Free Software Foundation, Inc.,
  28  *  675 Mass Ave, Cambridge, MA 02139, USA.
  29  */
  30
  31 #include <linux/types.h>
  32 #include <asm/mach-au1x00/au1000.h>
  33
  34 #define SERIAL_BASE   UART_BASE
  35 #define SER_CMD       0x7
  36 #define SER_DATA      0x1
  37 #define TX_BUSY       0x20
  38
  39 #define TIMEOUT       0xffffff
  40 #define SLOW_DOWN
  41
  42 static volatile unsigned long * const com1 = (unsigned long *)SERIAL_BASE;
  43
  44
  45 #ifdef SLOW_DOWN
  46 static inline void slow_down(void)
  47 {
  48     int k;
  49     for (k=0; k<10000; k++);
  50 }
  51 #else
  52 #define slow_down()
  53 #endif
  54
  55 void
  56 prom_putchar(const unsigned char c)
  57 {
  58     unsigned char ch;
  59     int i = 0;
  60
  61     do {
  62         ch = com1[SER_CMD];
  63         slow_down();
  64         i++;
  65         if (i>TIMEOUT) {
  66             break;
  67         }
  68     } while (0 == (ch & TX_BUSY));
  69     com1[SER_DATA] = c;
  70 }