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

     /*-
      * Copyright (c) 2010 Greg Ansley.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
      * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    /*
     * The SAM9 watchdog hardware can be programed only once. So we set the
     * hardware watchdog to 16 s in wdt_attach and only reset it in the wdt_tick
     * handler.  The watchdog is halted in processor debug mode.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/systm.h>
    #include <sys/watchdog.h>
    
    #include <machine/bus.h>
    
    #include <arm/at91/at91var.h>
    #include <arm/at91/at91_wdtreg.h>
    
    struct wdt_softc {
            struct mtx      sc_mtx;
            device_t        sc_dev;
            struct resource *mem_res;
            struct callout  tick_ch;
            eventhandler_tag sc_wet;
            void            *intrhand;
            u_int           cmd;
            u_int           interval;
    };
    
    static inline uint32_t
    RD4(struct wdt_softc *sc, bus_size_t off)
    {
    
            return (bus_read_4(sc->mem_res, off));
    }
    
    static inline void
    WR4(struct wdt_softc *sc, bus_size_t off, uint32_t val)
    {
    
            bus_write_4(sc->mem_res, off, val);
    }
    
    static int
    wdt_intr(void *argp)
    {
            struct wdt_softc *sc = argp;
    
    
            if (RD4(sc, WDT_SR) & (WDT_WDUNF | WDT_WDERR)) {
    #if defined(KDB) && !defined(KDB_UNATTENDED)
                    kdb_backtrace();
                    kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
    #else
                    panic("watchdog timeout");
    #endif
            }
            return (FILTER_STRAY);
    }
    
    /* User interface, see watchdog(9) */
    static void
    wdt_watchdog(void *argp, u_int cmd, int *error)
    {
            struct wdt_softc *sc = argp;
            u_int interval;
    
            mtx_lock(&sc->sc_mtx);
    
            *error = 0;
           sc->cmd = 0;
           interval = cmd & WD_INTERVAL;
           if (interval > WD_TO_16SEC)
                   *error = EOPNOTSUPP;
           else if (interval > 0)
                   sc->cmd = interval | WD_ACTIVE;
   
           /* We cannot turn off our watchdog so if user
            * fails to turn us on go to passive mode. */
           if ((sc->cmd & WD_ACTIVE) == 0)
                   sc->cmd = WD_PASSIVE;
   
           mtx_unlock(&sc->sc_mtx);
   }
   
   /* This routine is called no matter what state the user sets the
    * watchdog mode to. Called at a rate that is slightly less than
    * half the hardware timeout. */
   static void
   wdt_tick(void *argp)
   {
           struct wdt_softc *sc = argp;
   
           mtx_assert(&sc->sc_mtx, MA_OWNED);
           if (sc->cmd & (WD_ACTIVE | WD_PASSIVE))
                   WR4(sc, WDT_CR, WDT_KEY|WDT_WDRSTT);
   
           sc->cmd &= WD_PASSIVE;
           callout_reset(&sc->tick_ch, sc->interval, wdt_tick, sc);
   }
   
   static int
   wdt_probe(device_t dev)
   {
   
           if (at91_is_sam9() || at91_is_sam9xe()) {
                   device_set_desc(dev, "WDT");
                   return (0);
           }
           return (ENXIO);
   }
   
   static int
   wdt_attach(device_t dev)
   {
           static struct wdt_softc *sc;
           struct resource *irq;
           uint32_t wdt_mr;
           int rid, err;
   
           sc = device_get_softc(dev);
           sc->cmd = WD_PASSIVE;
           sc->sc_dev = dev;
   
           mtx_init(&sc->sc_mtx, device_get_nameunit(dev), "at91_wdt", MTX_DEF);
           callout_init_mtx(&sc->tick_ch, &sc->sc_mtx, 0);
   
           rid = 0;
           sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
               RF_ACTIVE);
   
           if (sc->mem_res == NULL)
                   panic("couldn't allocate wdt register resources");
   
           wdt_mr = RD4(sc, WDT_MR);
           if ((wdt_mr & WDT_WDRSTEN) == 0)
                   device_printf(dev, "Watchdog disabled! (Boot ROM?)\n");
           else {
   #ifdef WDT_RESET
                   /* Rude, full reset of whole system on watch dog timeout */
                   WR4(sc, WDT_MR, WDT_WDDBGHLT | WDT_WDD(0xC00)|
                       WDT_WDRSTEN| WDT_WDV(0xFFF));
   #else
                   /* Generate stack trace and panic on watchdog timeout*/
                   WR4(sc, WDT_MR, WDT_WDDBGHLT | WDT_WDD(0xC00)|
                       WDT_WDFIEN| WDT_WDV(0xFFF));
   #endif
                   /*
                    * This may have been set by Boot ROM so register value may
                    * not be what we just requested since this is a write once
                    * register.
                    */
                   wdt_mr = RD4(sc, WDT_MR);
                   if (wdt_mr & WDT_WDFIEN) {
                           rid = 0;
                           irq = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
                               RF_ACTIVE | RF_SHAREABLE);
                           if (!irq)
                                   panic("could not allocate interrupt.\n");
   
                           err = bus_setup_intr(dev, irq, INTR_TYPE_CLK, wdt_intr,
                               NULL, sc, &sc->intrhand);
                   }
   
                   /* interval * hz */
                   sc->interval = (((wdt_mr & WDT_WDV(~0)) + 1) * WDT_DIV) /
                       (WDT_CLOCK/hz);
   
                   device_printf(dev, "watchdog timeout: %d seconds\n",
                       sc->interval / hz);
   
                   /* Slightly less than 1/2 of watchdog hardware timeout */
                   sc->interval = (sc->interval/2) - (sc->interval/20);
                   callout_reset(&sc->tick_ch, sc->interval, wdt_tick, sc);
   
                   /* Register us as a watchdog */
                   sc->sc_wet = EVENTHANDLER_REGISTER(watchdog_list,
                       wdt_watchdog, sc, 0);
           }
           return (0);
   }
   
   static device_method_t wdt_methods[] = {
           DEVMETHOD(device_probe, wdt_probe),
           DEVMETHOD(device_attach, wdt_attach),
           DEVMETHOD_END
   };
   
   static driver_t wdt_driver = {
           "at91_wdt",
           wdt_methods,
           sizeof(struct wdt_softc),
   };
   
   static devclass_t wdt_devclass;
   
   DRIVER_MODULE(at91_wdt, atmelarm, wdt_driver, wdt_devclass, NULL, NULL);

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