firmware/target/sh/kernel-sh.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2002 by Björn Stenberg
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include "config.h"
  22 #include "system.h"
  23 #include "kernel.h"
  24 #include "panic.h"
  25
  26 void tick_start(unsigned int interval_in_ms)
  27 {
  28     unsigned long count;
  29
  30     count = CPU_FREQ * interval_in_ms / 1000 / 8;
  31
  32     if(count > 0x10000)
  33     {
  34         panicf("Error! The tick interval is too long (%d ms)\n",
  35                interval_in_ms);
  36         return;
  37     }
  38
  39     /* We are using timer 0 */
  40
  41     TSTR &= ~0x01; /* Stop the timer */
  42     TSNC &= ~0x01; /* No synchronization */
  43     TMDR &= ~0x01; /* Operate normally */
  44
  45     TCNT0 = 0;   /* Start counting at 0 */
  46     GRA0 = (unsigned short)(count - 1);
  47     TCR0 = 0x23; /* Clear at GRA match, sysclock/8 */
  48
  49     /* Enable interrupt on level 1 */
  50     IPRC = (IPRC & ~0x00f0) | 0x0010;
  51
  52     TSR0 &= ~0x01;
  53     TIER0 = 0xf9; /* Enable GRA match interrupt */
  54
  55     TSTR |= 0x01; /* Start timer 1 */
  56 }
  57
  58 void IMIA0(void) __attribute__ ((interrupt_handler));
  59 void IMIA0(void)
  60 {
  61     /* Run through the list of tick tasks */
  62     call_tick_tasks();
  63
  64     TSR0 &= ~0x01;
  65 }