00001 /* 00002 * Copyright (C) 2006 by egnite Software GmbH. All rights reserved. 00003 * 00004 * Redistribution and use in source and binary forms, with or without 00005 * modification, are permitted provided that the following conditions 00006 * are met: 00007 * 00008 * 1. Redistributions of source code must retain the above copyright 00009 * notice, this list of conditions and the following disclaimer. 00010 * 2. Redistributions in binary form must reproduce the above copyright 00011 * notice, this list of conditions and the following disclaimer in the 00012 * documentation and/or other materials provided with the distribution. 00013 * 3. Neither the name of the copyright holders nor the names of 00014 * contributors may be used to endorse or promote products derived 00015 * from this software without specific prior written permission. 00016 * 00017 * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH AND CONTRIBUTORS 00018 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00019 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00020 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL EGNITE 00021 * SOFTWARE GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00022 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00023 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 00024 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 00025 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 00026 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 00027 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 00028 * SUCH DAMAGE. 00029 * 00030 * For additional information see http://www.ethernut.de/ 00031 * 00032 */ 00033 00034 /* 00035 * $Log: wdt_at91.c,v $ 00036 * Revision 1.2 2006/05/25 09:13:22 haraldkipp 00037 * Platform independent watchdog API added. 00038 * 00039 * Revision 1.1 2006/02/23 15:36:35 haraldkipp 00040 * Added support for AT91 watchdog timer. 00041 * 00042 */ 00043 00044 #include <sys/timer.h> 00045 #include <dev/watchdog.h> 00046 00051 00052 static ureg_t nested; 00053 00060 u_long At91WatchDogStart(u_long ms, u_long xmode) 00061 { 00062 u_int cmval; 00063 00064 At91WatchDogDisable(); 00065 00066 /* 00067 * The watchdog counts down a 16 bit value, of which the upper 00068 * 4 bits are configurable and the lower 12 bits are set to 1. 00069 * Calculate the number of cycles required to count down the 00070 * upper 4 bits. 00071 */ 00072 cmval = ((NutGetCpuClock() / 1000) * ms) >> 13; 00073 00074 /* Check if MCK/8 is slow enough. */ 00075 if (cmval < WD_HPCV) { 00076 cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK8; 00077 } 00078 /* Check if MCK/32 is slow enough. */ 00079 else if ((cmval >>= 2) < WD_HPCV) { 00080 cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK32; 00081 } 00082 /* Check if MCK/128 is slow enough. */ 00083 else if ((cmval >>= 2) < WD_HPCV) { 00084 cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK128; 00085 } 00086 /* Check if MCK/1024 is slow enough. */ 00087 else if ((cmval >>= 3) < WD_HPCV) { 00088 cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK1024; 00089 } 00090 /* Use maximum. */ 00091 else { 00092 cmval = WD_HPCV | WD_WDCLKS_MCK1024; 00093 } 00094 outr(WD_CMR, WD_CKEY | cmval); 00095 if (xmode == 0) { 00096 xmode |= WD_RSTEN; 00097 } 00098 At91WatchDogRestart(); 00099 outr(WD_OMR, WD_OKEY | WD_WDEN | xmode); 00100 nested = 1; 00101 00102 return ms; 00103 } 00104 00111 void At91WatchDogRestart(void) 00112 { 00113 outr(WD_CR, WD_RSTKEY); 00114 } 00115 00122 void At91WatchDogDisable(void) 00123 { 00124 if (nested) { 00125 nested++; 00126 } 00127 outr(WD_OMR, WD_OKEY | (inr(WD_OMR) & ~WD_WDEN)); 00128 } 00129 00136 void At91WatchDogEnable(void) 00137 { 00138 if (nested > 1 && --nested == 1) { 00139 At91WatchDogRestart(); 00140 outr(WD_OMR, WD_OKEY | inr(WD_OMR) | WD_WDEN); 00141 } 00142 } 00143