arch/mips/alchemy/common/puts.c

   1 /*
   2  *
   3  * BRIEF MODULE DESCRIPTION
   4  *      Low level UART routines to directly access Alchemy UART.
   5  *
   6  * Copyright 2001, 2008 MontaVista Software Inc.
   7  * Author: MontaVista Software, Inc. <source@mvista.com>
   8  *
   9  *  This program is free software; you can redistribute  it and/or modify it
  10  *  under  the terms of  the GNU General  Public License as published by the
  11  *  Free Software Foundation;  either version 2 of the  License, or (at your
  12  *  option) any later version.
  13  *
  14  *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
  15  *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
  16  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
  17  *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
  18  *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
  20  *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  21  *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
  22  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  *  You should have received a copy of the  GNU General Public License along
  26  *  with this program; if not, write  to the Free Software Foundation, Inc.,
  27  *  675 Mass Ave, Cambridge, MA 02139, USA.
  28  */
  29
  30 #include <asm/mach-au1x00/au1000.h>
  31
  32 #define SERIAL_BASE   UART_BASE
  33 #define SER_CMD       0x7
  34 #define SER_DATA      0x1
  35 #define TX_BUSY       0x20
  36
  37 #define TIMEOUT       0xffffff
  38 #define SLOW_DOWN
  39
  40 static volatile unsigned long * const com1 = (unsigned long *)SERIAL_BASE;
  41
  42 #ifdef SLOW_DOWN
  43 static inline void slow_down(void)
  44 {
  45         int k;
  46
  47         for (k = 0; k < 10000; k++);
  48 }
  49 #else
  50 #define slow_down()
  51 #endif
  52
  53 void
  54 prom_putchar(const unsigned char c)
  55 {
  56         unsigned char ch;
  57         int i = 0;
  58
  59         do {
  60                 ch = com1[SER_CMD];
  61                 slow_down();
  62                 i++;
  63                 if (i > TIMEOUT)
  64                         break;
  65         } while (0 == (ch & TX_BUSY));
  66
  67         com1[SER_DATA] = c;
  68 }