FreeBSD/Linux Kernel Cross Reference
sys/arm/at91/at91_pit.c

     /*-
      * Copyright (c) 2009 Gallon Sylvestre.  All rights reserved.
      * 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.
     */
    
    #include "opt_platform.h"
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/resource.h>
    #include <sys/systm.h>
    #include <sys/rman.h>
    #include <sys/time.h>
    #include <sys/timetc.h>
    #include <sys/watchdog.h>
    
    #include <machine/bus.h>
    #include <machine/cpu.h>
    #include <machine/cpufunc.h>
    #include <machine/frame.h>
    #include <machine/intr.h>
    #include <machine/resource.h>
    
    #include <arm/at91/at91var.h>
    #include <arm/at91/at91_pitreg.h>
    
    #ifdef FDT
    #include <dev/fdt/fdt_common.h>
    #include <dev/ofw/ofw_bus.h>
    #include <dev/ofw/ofw_bus_subr.h>
    #endif
    
    #ifndef PIT_PRESCALE
    #define PIT_PRESCALE (16)
    #endif
    
    static struct pit_softc {
            struct resource *mem_res;       /* Memory resource */
            void            *intrhand;      /* Interrupt handle */
            device_t        sc_dev;
    } *sc;
    
    static uint32_t timecount = 0;
    static unsigned at91_pit_get_timecount(struct timecounter *tc);
    static int pit_intr(void *arg);
    
    static inline uint32_t
    RD4(struct pit_softc *sc, bus_size_t off)
    {
    
            return (bus_read_4(sc->mem_res, off));
    }
    
    static inline void
    WR4(struct pit_softc *sc, bus_size_t off, uint32_t val)
    {
    
            bus_write_4(sc->mem_res, off, val);
    }
    
    void
    at91_pit_delay(int us)
    {
            int32_t cnt, last, piv;
            uint64_t pit_freq;
            const uint64_t mhz  = 1E6;
    
            if (sc == NULL)
                    return;
    
            last = PIT_PIV(RD4(sc, PIT_PIIR));
    
            /* Max delay ~= 260s. @ 133Mhz */
           pit_freq = at91_master_clock / PIT_PRESCALE;
           cnt  = ((pit_freq * us) + (mhz -1)) / mhz;
           cnt  = (cnt <= 0) ? 1 : cnt;
   
           while (cnt > 0) {
                   piv = PIT_PIV(RD4(sc, PIT_PIIR));
                           cnt  -= piv - last ;
                   if (piv < last)
                           cnt -= PIT_PIV(~0u) - last;
                   last = piv;
           }
   }
   
   static struct timecounter at91_pit_timecounter = {
           at91_pit_get_timecount, /* get_timecount */
           NULL, /* no poll_pps */
           0xffffffff, /* counter mask */
           0 / PIT_PRESCALE, /* frequency */
           "AT91SAM9 timer", /* name */
           1000 /* quality */
   };
   
   static int
   at91_pit_probe(device_t dev)
   {
   #ifdef FDT
           if (!ofw_bus_is_compatible(dev, "atmel,at91sam9260-pit"))
                   return (ENXIO);
   #endif
           device_set_desc(dev, "AT91SAM9 PIT");
           return (0);
   }
   
   static int
   at91_pit_attach(device_t dev)
   {
           void *ih;
           int rid, err = 0;
           struct resource *irq;
   
           sc = device_get_softc(dev);
           sc->sc_dev = dev;
   
           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 register resources");
   
           rid = 0;
           irq = bus_alloc_resource(dev, SYS_RES_IRQ, &rid, 1, 1, 1,
               RF_ACTIVE | RF_SHAREABLE);
           if (!irq) {
                   device_printf(dev, "could not allocate interrupt resources.\n");
                   err = ENOMEM;
                   goto out;
           }
   
           /* Activate the interrupt. */
           err = bus_setup_intr(dev, irq, INTR_TYPE_CLK, pit_intr, NULL, NULL,
               &ih);
   
           at91_pit_timecounter.tc_frequency =  at91_master_clock / PIT_PRESCALE;
           tc_init(&at91_pit_timecounter);
   
           /* Enable the PIT here. */
           WR4(sc, PIT_MR, PIT_PIV(at91_master_clock / PIT_PRESCALE / hz) |
               PIT_EN | PIT_IEN);
   out:
           return (err);
   }
   
   
   static int
   pit_intr(void *arg)
   {
           struct trapframe *fp = arg;
           uint32_t icnt;
   
           if (RD4(sc, PIT_SR) & PIT_PITS_DONE) {
                   icnt = RD4(sc, PIT_PIVR) >> 20;
   
                   /* Just add in the overflows we just read */
                   timecount +=  PIT_PIV(RD4(sc, PIT_MR)) * icnt;
   
                   hardclock(TRAPF_USERMODE(fp), TRAPF_PC(fp));
                   return (FILTER_HANDLED);
           }
           return (FILTER_STRAY);
   }
   
   static unsigned
   at91_pit_get_timecount(struct timecounter *tc)
   {
           uint32_t piir, icnt;
   
           piir = RD4(sc, PIT_PIIR); /* Current  count | over flows */
           icnt = piir >> 20;      /* Overflows */
           return (timecount + PIT_PIV(piir) + PIT_PIV(RD4(sc, PIT_MR)) * icnt);
   }
   
   static device_method_t at91_pit_methods[] = {
           DEVMETHOD(device_probe, at91_pit_probe),
           DEVMETHOD(device_attach, at91_pit_attach),
           DEVMETHOD_END
   };
   
   static driver_t at91_pit_driver = {
           "at91_pit",
           at91_pit_methods,
           sizeof(struct pit_softc),
   };
   
   static devclass_t at91_pit_devclass;
   
   #ifdef FDT
   DRIVER_MODULE(at91_pit, simplebus, at91_pit_driver, at91_pit_devclass, NULL,
       NULL);
   #else
   DRIVER_MODULE(at91_pit, atmelarm, at91_pit_driver, at91_pit_devclass, NULL,
       NULL);
   #endif

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