wdt_at91.c

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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 1.3  2008/08/11 06:59:13  haraldkipp
00037  * BSD types replaced by stdint types (feature request #1282721).
00038  *
00039  * Revision 1.2  2006/05/25 09:13:22  haraldkipp
00040  * Platform independent watchdog API added.
00041  *
00042  * Revision 1.1  2006/02/23 15:36:35  haraldkipp
00043  * Added support for AT91 watchdog timer.
00044  *
00045  */
00046 
00047 #include <sys/timer.h>
00048 #include <dev/watchdog.h>
00049 
00054 
00055 static ureg_t nested;
00056 
00063 uint32_t At91WatchDogStart(uint32_t ms, uint32_t xmode)
00064 {
00065     u_int cmval;
00066 
00067     At91WatchDogDisable();
00068 
00069     /*
00070      * The watchdog counts down a 16 bit value, of which the upper
00071      * 4 bits are configurable and the lower 12 bits are set to 1.
00072      * Calculate the number of cycles required to count down the
00073      * upper 4 bits.
00074      */
00075     cmval = ((NutGetCpuClock() / 1000) * ms) >> 13;
00076     
00077     /* Check if MCK/8 is slow enough. */
00078     if (cmval < WD_HPCV) {
00079         cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK8;
00080     }
00081     /* Check if MCK/32 is slow enough. */
00082     else if ((cmval >>= 2) < WD_HPCV) {
00083         cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK32;
00084     }
00085     /* Check if MCK/128 is slow enough. */
00086     else if ((cmval >>= 2) < WD_HPCV) {
00087         cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK128;
00088     }
00089     /* Check if MCK/1024 is slow enough. */
00090     else if ((cmval >>= 3) < WD_HPCV) {
00091         cmval = (cmval & WD_HPCV) | WD_WDCLKS_MCK1024;
00092     }
00093     /* Use maximum. */
00094     else {
00095         cmval = WD_HPCV | WD_WDCLKS_MCK1024;
00096     }
00097     outr(WD_CMR, WD_CKEY | cmval);
00098     if (xmode == 0) {
00099         xmode |= WD_RSTEN;
00100     }
00101     At91WatchDogRestart();
00102     outr(WD_OMR, WD_OKEY | WD_WDEN | xmode);
00103     nested = 1;
00104 
00105     return ms;
00106 }
00107 
00114 void At91WatchDogRestart(void)
00115 {
00116     outr(WD_CR, WD_RSTKEY);
00117 }
00118 
00125 void At91WatchDogDisable(void)
00126 {
00127     if (nested) {
00128         nested++;
00129     }
00130     outr(WD_OMR, WD_OKEY | (inr(WD_OMR) & ~WD_WDEN));
00131 }
00132 
00139 void At91WatchDogEnable(void)
00140 {
00141     if (nested > 1 && --nested == 1) {
00142         At91WatchDogRestart();
00143         outr(WD_OMR, WD_OKEY | inr(WD_OMR) | WD_WDEN);
00144     }
00145 }
00146 

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