at91_wdt.c

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    1 /*-
    2  * Copyright (c) 2010 Greg Ansley.  All rights reserved.
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions
    6  * are met:
    7  * 1. Redistributions of source code must retain the above copyright
    8  *    notice, this list of conditions and the following disclaimer.
    9  * 2. Redistributions in binary form must reproduce the above copyright
   10  *    notice, this list of conditions and the following disclaimer in the
   11  *    documentation and/or other materials provided with the distribution.
   12  *
   13  * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   16  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
   17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   23  * SUCH DAMAGE.
   24  */
   25 
   26 /*
   27  * The sam9 watchdog hardware can be programed only once. So we set the hardware
   28  * watchdog to 16s in wdt_attach and only reset it in the wdt_tick
   29  * handler. The watchdog is halted in processor debug mode.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/9.0/sys/arm/at91/at91_wdt.c 221025 2011-04-25 18:15:45Z cognet $");
   34 
   35 #include <sys/param.h>
   36 #include <sys/bus.h>
   37 #include <sys/kdb.h>
   38 #include <sys/kernel.h>
   39 #include <sys/module.h>
   40 #include <sys/systm.h>
   41 #include <sys/watchdog.h>
   42 
   43 #include <machine/bus.h>
   44 
   45 #include <arm/at91/at91var.h>
   46 #include <arm/at91/at91_wdtreg.h>
   47 
   48 struct wdt_softc {
   49         struct mtx      sc_mtx;
   50         device_t        sc_dev;
   51         struct resource *mem_res;
   52         struct callout  tick_ch;
   53         eventhandler_tag sc_wet;
   54         void            *intrhand;
   55         u_int           cmd;
   56         u_int           interval;
   57 };
   58 
   59 static inline uint32_t
   60 RD4(struct wdt_softc *sc, bus_size_t off)
   61 {
   62         return (bus_read_4(sc->mem_res, off));
   63 }
   64 
   65 static inline void
   66 WR4(struct wdt_softc *sc, bus_size_t off, uint32_t val)
   67 {
   68         bus_write_4(sc->mem_res, off, val);
   69 }
   70 
   71 static int
   72 wdt_intr(void *argp)
   73 {
   74         struct wdt_softc *sc = argp;
   75 
   76 
   77         if (RD4(sc, WDT_SR) & (WDT_WDUNF | WDT_WDERR)) {
   78 #if defined(KDB) && !defined(KDB_UNATTENDED)
   79                 kdb_backtrace();
   80                 kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
   81 #else
   82                 panic("watchdog timeout");
   83 #endif
   84         }
   85         return (FILTER_STRAY);
   86 }
   87 
   88 /* User interface, see watchdog(9) */
   89 static void
   90 wdt_watchdog(void *argp, u_int cmd, int *error)
   91 {
   92         struct wdt_softc *sc = argp;
   93         u_int interval;
   94 
   95         mtx_lock(&sc->sc_mtx);
   96 
   97         *error = 0;
   98         sc->cmd = 0;
   99         interval = cmd & WD_INTERVAL;
  100         if (interval > WD_TO_16SEC)
  101                 *error = EOPNOTSUPP;
  102         else if (interval > 0)
  103                 sc->cmd = interval | WD_ACTIVE;
  104 
  105         /* We cannot turn off our watchdog so if user
  106          * fails to turn us on go to passive mode. */
  107         if ((sc->cmd & WD_ACTIVE) == 0)
  108                 sc->cmd = WD_PASSIVE;
  109 
  110         mtx_unlock(&sc->sc_mtx);
  111 }
  112 
  113 /* This routine is called no matter what state the user sets the
  114  * watchdog mode to. Called at a rate that is slightly less than
  115  * half the hardware timeout. */
  116 static void
  117 wdt_tick(void *argp)
  118 {
  119         struct wdt_softc *sc = argp;
  120 
  121         mtx_assert(&sc->sc_mtx, MA_OWNED);
  122         if (sc->cmd & (WD_ACTIVE | WD_PASSIVE))
  123                 WR4(sc, WDT_CR, WDT_KEY|WDT_WDRSTT);
  124 
  125         sc->cmd &= WD_PASSIVE;
  126         callout_reset(&sc->tick_ch, sc->interval, wdt_tick, sc);
  127 }
  128 
  129 static int
  130 wdt_probe(device_t dev)
  131 {
  132 
  133         if (at91_is_sam9()) {
  134                 device_set_desc(dev, "WDT");
  135                 return (0);
  136         }
  137         return (ENXIO);
  138 }
  139 
  140 static int
  141 wdt_attach(device_t dev)
  142 {
  143         static struct wdt_softc *sc;
  144         struct resource *irq;
  145         uint32_t wdt_mr;
  146         int rid, err;
  147 
  148         sc = device_get_softc(dev);
  149         sc->cmd = WD_PASSIVE;
  150         sc->sc_dev = dev;
  151 
  152         mtx_init(&sc->sc_mtx, device_get_nameunit(dev), "at91_wdt", MTX_DEF);
  153         callout_init_mtx(&sc->tick_ch, &sc->sc_mtx, 0);
  154 
  155         rid = 0;
  156         sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
  157             RF_ACTIVE);
  158 
  159         if (sc->mem_res == NULL)
  160                panic("couldn't allocate wdt register resources");
  161 
  162         wdt_mr = RD4(sc, WDT_MR);
  163         if ((wdt_mr & WDT_WDRSTEN) == 0)
  164                 device_printf(dev, "Watchdog disabled! (Boot ROM?)\n");
  165         else {
  166 #ifdef WDT_RESET
  167                 /* Rude, full reset of whole system on watch dog timeout */
  168                 WR4(sc, WDT_MR, WDT_WDDBGHLT | WDT_WDD(0xC00)|
  169                     WDT_WDRSTEN| WDT_WDV(0xFFF));
  170 #else
  171                 /* Generate stack trace and panic on watchdog timeout*/
  172                 WR4(sc, WDT_MR, WDT_WDDBGHLT | WDT_WDD(0xC00)|
  173                     WDT_WDFIEN| WDT_WDV(0xFFF));
  174 #endif
  175                 /* This may have been set by Boot ROM so register value
  176                  * may not be  what we just requested since this is a
  177                  * write once register. */
  178                 wdt_mr = RD4(sc, WDT_MR);
  179                 if (wdt_mr & WDT_WDFIEN) {
  180                         rid = 0;
  181                         irq = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
  182                             RF_ACTIVE | RF_SHAREABLE);
  183                         if (!irq)
  184                                 panic("could not allocate interrupt.\n");
  185 
  186                         err = bus_setup_intr(dev, irq, INTR_TYPE_CLK, wdt_intr,
  187                                 NULL, sc, &sc->intrhand);
  188                 }
  189 
  190                 /* interval * hz */
  191                 sc->interval = (((wdt_mr & WDT_WDV(~0)) + 1) * WDT_DIV) /
  192                         (WDT_CLOCK/hz);
  193 
  194                 device_printf(dev, "watchdog timeout: %d seconds\n",
  195                      sc->interval/hz);
  196 
  197                 /* Slightly less than 1/2 of watchdog hardware timeout */
  198                 sc->interval = (sc->interval/2) - (sc->interval/20);
  199                 callout_reset(&sc->tick_ch, sc->interval, wdt_tick, sc);
  200 
  201                 /* Register us as a watchdog */
  202                 sc->sc_wet = EVENTHANDLER_REGISTER(watchdog_list,
  203                     wdt_watchdog, sc, 0);
  204         }
  205         return (0);
  206 }
  207 
  208 static device_method_t wdt_methods[] = {
  209         DEVMETHOD(device_probe, wdt_probe),
  210         DEVMETHOD(device_attach, wdt_attach),
  211         {0,0},
  212 };
  213 
  214 static driver_t wdt_driver = {
  215         "at91_wdt",
  216         wdt_methods,
  217         sizeof(struct wdt_softc),
  218 };
  219 
  220 static devclass_t wdt_devclass;
  221 
  222 DRIVER_MODULE(at91_wdt, atmelarm, wdt_driver, wdt_devclass, 0, 0);

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FreeBSD/Linux Kernel Cross Reference sys/arm/at91/at91_wdt.c

FreeBSD/Linux Kernel Cross Reference
sys/arm/at91/at91_wdt.c