FreeBSD/Linux Kernel Cross Reference
sys/arm/at91/at91_st.c

     /*-
      * Copyright (c) 2005 Olivier Houchard.  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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/time.h>
    #include <sys/bus.h>
    #include <sys/resource.h>
    #include <sys/rman.h>
    #include <sys/timetc.h>
    #include <sys/watchdog.h>
    
    #include <machine/bus.h>
    #include <machine/cpu.h>
    #include <machine/cpufunc.h>
    #include <machine/resource.h>
    #include <machine/frame.h>
    #include <machine/intr.h>
    #include <arm/at91/at91rm92reg.h>
    #include <arm/at91/at91var.h>
    #include <arm/at91/at91_streg.h>
    
    static struct at91st_softc {
            bus_space_tag_t         sc_st;
            bus_space_handle_t      sc_sh;
            device_t                sc_dev;
            eventhandler_tag        sc_wet; /* watchdog event handler tag */
    } *timer_softc;
    
    #define RD4(off) \
            bus_space_read_4(timer_softc->sc_st, timer_softc->sc_sh, (off))
    #define WR4(off, val) \
            bus_space_write_4(timer_softc->sc_st, timer_softc->sc_sh, (off), (val))
    
    static void at91st_watchdog(void *, u_int, int *);
    
    static inline int
    st_crtr(void)
    {
            int cur1, cur2;
            do {
                    cur1 = RD4(ST_CRTR);
                    cur2 = RD4(ST_CRTR);
            } while (cur1 != cur2);
            return (cur1);
    }
    
    static unsigned at91st_get_timecount(struct timecounter *tc);
    
    static struct timecounter at91st_timecounter = {
            at91st_get_timecount, /* get_timecount */
            NULL, /* no poll_pps */
            0xfffffu, /* counter_mask */
            32768, /* frequency */
            "AT91RM9200 timer", /* name */
            1000 /* quality */
    };
    
    static int
    at91st_probe(device_t dev)
    {
    
            device_set_desc(dev, "ST");
            return (0);
    }
    
    static int
    at91st_attach(device_t dev)
    {
            struct at91_softc *sc = device_get_softc(device_get_parent(dev));
    
            timer_softc = device_get_softc(dev);
           timer_softc->sc_st = sc->sc_st;
           timer_softc->sc_dev = dev;
           if (bus_space_subregion(sc->sc_st, sc->sc_sh, AT91RM92_ST_BASE,
               AT91RM92_ST_SIZE, &timer_softc->sc_sh) != 0)
                   panic("couldn't subregion timer registers");
           /*
            * Real time counter increments every clock cycle, need to set before
            * initializing clocks so that DELAY works.
            */
           WR4(ST_RTMR, 1);
           /* Disable all interrupts */
           WR4(ST_IDR, 0xffffffff);
           /* disable watchdog timer */
           WR4(ST_WDMR, 0);
   
           timer_softc->sc_wet = EVENTHANDLER_REGISTER(watchdog_list,
             at91st_watchdog, dev, 0);
           device_printf(dev,
             "watchdog registered, timeout intervall max. 64 sec\n");
           return (0);
   }
   
   static device_method_t at91st_methods[] = {
           DEVMETHOD(device_probe, at91st_probe),
           DEVMETHOD(device_attach, at91st_attach),
           {0, 0},
   };
   
   static driver_t at91st_driver = {
           "at91_st",
           at91st_methods,
           sizeof(struct at91st_softc),
   };
   static devclass_t at91st_devclass;
   
   DRIVER_MODULE(at91_st, atmelarm, at91st_driver, at91st_devclass, 0, 0);
   
   static unsigned
   at91st_get_timecount(struct timecounter *tc)
   {
           return (st_crtr());
   }
   
   /*
    * t below is in a weird unit.  The watchdog is set to 2^t
    * nanoseconds.  Since our watchdog timer can't really do that too
    * well, we approximate it by assuming that the timeout interval for
    * the lsb is 2^22 ns, which is 4.194ms.  This is an overestimation of
    * the actual time (3.906ms), but close enough for watchdogging.
    * These approximations, though a violation of the spec, improve the
    * performance of the application which typically specifies things as
    * WD_TO_32SEC.  In that last case, we'd wait 32s before the wdog
    * reset.  The spec says we should wait closer to 34s, but given how
    * it is likely to be used, and the extremely coarse nature time
    * interval, I think this is the best solution.
    */
   static void
   at91st_watchdog(void *argp, u_int cmd, int *error)
   {
           uint32_t wdog;
           int t;
   
           t = cmd & WD_INTERVAL;
           if (t >= 22 && t <= 37) {
                   wdog = (1 << (t - 22)) | ST_WDMR_RSTEN;
                   *error = 0;
           } else {
                   wdog = 0;
           }
           WR4(ST_WDMR, wdog);
           WR4(ST_CR, ST_CR_WDRST);
   }
   
   static int
   clock_intr(void *arg)
   {
           struct trapframe *fp = arg;
   
           /* The interrupt is shared, so we have to make sure it's for us. */
           if (RD4(ST_SR) & ST_SR_PITS) {
                   hardclock(TRAPF_USERMODE(fp), TRAPF_PC(fp));
                   return (FILTER_HANDLED);
           }
           return (FILTER_STRAY);
   }
   
   void
   cpu_initclocks(void)
   {
           int rel_value;
           struct resource *irq;
           int rid = 0;
           void *ih;
           device_t dev = timer_softc->sc_dev;
   
           rel_value = 32768 / hz;
           if (rel_value < 1)
                   rel_value = 1;
           if (32768 % hz) {
                   printf("Cannot get %d Hz clock; using %dHz\n", hz, 32768 / rel_value);
                   hz = 32768 / rel_value;
                   tick = 1000000 / hz;
           }
           /* Disable all interrupts. */
           WR4(ST_IDR, 0xffffffff);
           /* The system timer shares the system irq (1) */
           irq = bus_alloc_resource(dev, SYS_RES_IRQ, &rid, 1, 1, 1,
             RF_ACTIVE | RF_SHAREABLE);
           if (!irq)
                   panic("Unable to allocate irq for the system timer");
           else
                   bus_setup_intr(dev, irq, INTR_TYPE_CLK,
                       clock_intr, NULL, NULL, &ih);
   
           WR4(ST_PIMR, rel_value);
   
           /* Enable PITS interrupts. */
           WR4(ST_IER, ST_SR_PITS);
           tc_init(&at91st_timecounter);
   }
   
   void
   DELAY(int n)
   {
           uint32_t start, end, cur;
   
           start = st_crtr();
           n = (n * 1000) / 32768;
           if (n <= 0)
                   n = 1;
           end = (start + n) & ST_CRTR_MASK;
           cur = start;
           if (start > end) {
                   while (cur >= start || cur < end)
                           cur = st_crtr();
           } else {
                   while (cur < end)
                           cur = st_crtr();
           }
   }
   
   void
   cpu_reset(void)
   {
           /*
            * Reset the CPU by programmig the watchdog timer to reset the
            * CPU after 128 'slow' clocks, or about ~4ms.  Loop until
            * the reset happens for safety.
            */
           WR4(ST_WDMR, ST_WDMR_RSTEN | 2);
           WR4(ST_CR, ST_CR_WDRST);
           while (1)
                   continue;
   }
   
   void
   cpu_startprofclock(void)
   {
   }
   
   void
   cpu_stopprofclock(void)
   {
   }

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