FreeBSD/Linux Kernel Cross Reference
sys/x86/isa/clock.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1990 The Regents of the University of California.
      * Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org>
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * William Jolitz and Don Ahn.
     *
     * 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.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 THE REGENTS 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.
     *
     *      from: @(#)clock.c       7.2 (Berkeley) 5/12/91
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    /*
     * Routines to handle clock hardware.
     */
    
    #include "opt_clock.h"
    #include "opt_isa.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/lock.h>
    #include <sys/kdb.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/rman.h>
    #include <sys/sched.h>
    #include <sys/smp.h>
    #include <sys/sysctl.h>
    #include <sys/timeet.h>
    #include <sys/timetc.h>
    
    #include <machine/clock.h>
    #include <machine/cpu.h>
    #include <machine/intr_machdep.h>
    #include <machine/ppireg.h>
    #include <machine/timerreg.h>
    #include <x86/init.h>
    
    #include <isa/rtc.h>
    #ifdef DEV_ISA
    #include <isa/isareg.h>
    #include <isa/isavar.h>
    #endif
    
    int     clkintr_pending;
    #ifndef TIMER_FREQ
    #define TIMER_FREQ   1193182
    #endif
    u_int   i8254_freq = TIMER_FREQ;
    TUNABLE_INT("hw.i8254.freq", &i8254_freq);
    int     i8254_max_count;
    static int i8254_timecounter = 1;
    
    static  struct mtx clock_lock;
    static  struct intsrc *i8254_intsrc;
    static  uint16_t i8254_lastcount;
    static  uint16_t i8254_offset;
    static  int     (*i8254_pending)(struct intsrc *);
    static  int     i8254_ticked;
    
    struct attimer_softc {
            int intr_en;
            int port_rid, intr_rid;
            struct resource *port_res;
            struct resource *intr_res;
            void *intr_handler;
            struct timecounter tc;
           struct eventtimer et;
           int             mode;
   #define MODE_STOP       0
   #define MODE_PERIODIC   1
   #define MODE_ONESHOT    2
           uint32_t        period;
   };
   static struct attimer_softc *attimer_sc = NULL;
   
   static int timer0_period = -2;
   static int timer0_mode = 0xffff;
   static int timer0_last = 0xffff;
   
   /* Values for timerX_state: */
   #define RELEASED        0
   #define RELEASE_PENDING 1
   #define ACQUIRED        2
   #define ACQUIRE_PENDING 3
   
   static  u_char  timer2_state;
   
   static  unsigned i8254_get_timecount(struct timecounter *tc);
   static  void    set_i8254_freq(int mode, uint32_t period);
   
   void
   clock_init(void)
   {
           /* Init the clock lock */
           mtx_init(&clock_lock, "clk", NULL, MTX_SPIN | MTX_NOPROFILE);
           /* Init the clock in order to use DELAY */
           init_ops.early_clock_source_init();
   }
   
   static int
   clkintr(void *arg)
   {
           struct attimer_softc *sc = (struct attimer_softc *)arg;
   
           if (i8254_timecounter && sc->period != 0) {
                   mtx_lock_spin(&clock_lock);
                   if (i8254_ticked)
                           i8254_ticked = 0;
                   else {
                           i8254_offset += i8254_max_count;
                           i8254_lastcount = 0;
                   }
                   clkintr_pending = 0;
                   mtx_unlock_spin(&clock_lock);
           }
   
           if (sc->et.et_active && sc->mode != MODE_STOP)
                   sc->et.et_event_cb(&sc->et, sc->et.et_arg);
   
           return (FILTER_HANDLED);
   }
   
   int
   timer_spkr_acquire(void)
   {
           int mode;
   
           mode = TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT;
   
           if (timer2_state != RELEASED)
                   return (-1);
           timer2_state = ACQUIRED;
   
           /*
            * This access to the timer registers is as atomic as possible
            * because it is a single instruction.  We could do better if we
            * knew the rate.  Use of splclock() limits glitches to 10-100us,
            * and this is probably good enough for timer2, so we aren't as
            * careful with it as with timer0.
            */
           outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
   
           ppi_spkr_on();          /* enable counter2 output to speaker */
           return (0);
   }
   
   int
   timer_spkr_release(void)
   {
   
           if (timer2_state != ACQUIRED)
                   return (-1);
           timer2_state = RELEASED;
           outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
   
           ppi_spkr_off();         /* disable counter2 output to speaker */
           return (0);
   }
   
   void
   timer_spkr_setfreq(int freq)
   {
   
           freq = i8254_freq / freq;
           mtx_lock_spin(&clock_lock);
           outb(TIMER_CNTR2, freq & 0xff);
           outb(TIMER_CNTR2, freq >> 8);
           mtx_unlock_spin(&clock_lock);
   }
   
   static int
   getit(void)
   {
           int high, low;
   
           mtx_lock_spin(&clock_lock);
   
           /* Select timer0 and latch counter value. */
           outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
   
           low = inb(TIMER_CNTR0);
           high = inb(TIMER_CNTR0);
   
           mtx_unlock_spin(&clock_lock);
           return ((high << 8) | low);
   }
   
   /*
    * Wait "n" microseconds.
    * Relies on timer 1 counting down from (i8254_freq / hz)
    * Note: timer had better have been programmed before this is first used!
    */
   void
   i8254_delay(int n)
   {
           int delta, prev_tick, tick, ticks_left;
   #ifdef DELAYDEBUG
           int getit_calls = 1;
           int n1;
           static int state = 0;
   
           if (state == 0) {
                   state = 1;
                   for (n1 = 1; n1 <= 10000000; n1 *= 10)
                           DELAY(n1);
                   state = 2;
           }
           if (state == 1)
                   printf("DELAY(%d)...", n);
   #endif
           /*
            * Read the counter first, so that the rest of the setup overhead is
            * counted.  Guess the initial overhead is 20 usec (on most systems it
            * takes about 1.5 usec for each of the i/o's in getit().  The loop
            * takes about 6 usec on a 486/33 and 13 usec on a 386/20.  The
            * multiplications and divisions to scale the count take a while).
            *
            * However, if ddb is active then use a fake counter since reading
            * the i8254 counter involves acquiring a lock.  ddb must not do
            * locking for many reasons, but it calls here for at least atkbd
            * input.
            */
   #ifdef KDB
           if (kdb_active)
                   prev_tick = 1;
           else
   #endif
                   prev_tick = getit();
           n -= 0;                 /* XXX actually guess no initial overhead */
           /*
            * Calculate (n * (i8254_freq / 1e6)) without using floating point
            * and without any avoidable overflows.
            */
           if (n <= 0)
                   ticks_left = 0;
           else if (n < 256)
                   /*
                    * Use fixed point to avoid a slow division by 1000000.
                    * 39099 = 1193182 * 2^15 / 10^6 rounded to nearest.
                    * 2^15 is the first power of 2 that gives exact results
                    * for n between 0 and 256.
                    */
                   ticks_left = ((u_int)n * 39099 + (1 << 15) - 1) >> 15;
           else
                   /*
                    * Don't bother using fixed point, although gcc-2.7.2
                    * generates particularly poor code for the long long
                    * division, since even the slow way will complete long
                    * before the delay is up (unless we're interrupted).
                    */
                   ticks_left = ((u_int)n * (long long)i8254_freq + 999999)
                                / 1000000;
   
           while (ticks_left > 0) {
   #ifdef KDB
                   if (kdb_active) {
                           inb(0x84);
                           tick = prev_tick - 1;
                           if (tick <= 0)
                                   tick = i8254_max_count;
                   } else
   #endif
                           tick = getit();
   #ifdef DELAYDEBUG
                   ++getit_calls;
   #endif
                   delta = prev_tick - tick;
                   prev_tick = tick;
                   if (delta < 0) {
                           delta += i8254_max_count;
                           /*
                            * Guard against i8254_max_count being wrong.
                            * This shouldn't happen in normal operation,
                            * but it may happen if set_i8254_freq() is
                            * traced.
                            */
                           if (delta < 0)
                                   delta = 0;
                   }
                   ticks_left -= delta;
           }
   #ifdef DELAYDEBUG
           if (state == 1)
                   printf(" %d calls to getit() at %d usec each\n",
                          getit_calls, (n + 5) / getit_calls);
   #endif
   }
   
   static void
   set_i8254_freq(int mode, uint32_t period)
   {
           int new_count, new_mode;
   
           mtx_lock_spin(&clock_lock);
           if (mode == MODE_STOP) {
                   if (i8254_timecounter) {
                           mode = MODE_PERIODIC;
                           new_count = 0x10000;
                   } else
                           new_count = -1;
           } else {
                   new_count = min(((uint64_t)i8254_freq * period +
                       0x80000000LLU) >> 32, 0x10000);
           }
           if (new_count == timer0_period)
                   goto out;
           i8254_max_count = ((new_count & ~0xffff) != 0) ? 0xffff : new_count;
           timer0_period = (mode == MODE_PERIODIC) ? new_count : -1;
           switch (mode) {
           case MODE_STOP:
                   new_mode = TIMER_SEL0 | TIMER_INTTC | TIMER_16BIT;
                   outb(TIMER_MODE, new_mode);
                   outb(TIMER_CNTR0, 0);
                   outb(TIMER_CNTR0, 0);
                   break;
           case MODE_PERIODIC:
                   new_mode = TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT;
                   outb(TIMER_MODE, new_mode);
                   outb(TIMER_CNTR0, new_count & 0xff);
                   outb(TIMER_CNTR0, new_count >> 8);
                   break;
           case MODE_ONESHOT:
                   if (new_count < 256 && timer0_last < 256) {
                           new_mode = TIMER_SEL0 | TIMER_INTTC | TIMER_LSB;
                           if (new_mode != timer0_mode)
                                   outb(TIMER_MODE, new_mode);
                           outb(TIMER_CNTR0, new_count & 0xff);
                           break;
                   }
                   new_mode = TIMER_SEL0 | TIMER_INTTC | TIMER_16BIT;
                   if (new_mode != timer0_mode)
                           outb(TIMER_MODE, new_mode);
                   outb(TIMER_CNTR0, new_count & 0xff);
                   outb(TIMER_CNTR0, new_count >> 8);
                   break;
           default:
                   panic("set_i8254_freq: unknown operational mode");
           }
           timer0_mode = new_mode;
           timer0_last = new_count;
   out:
           mtx_unlock_spin(&clock_lock);
   }
   
   static void
   i8254_restore(void)
   {
   
           timer0_period = -2;
           timer0_mode = 0xffff;
           timer0_last = 0xffff;
           if (attimer_sc != NULL)
                   set_i8254_freq(attimer_sc->mode, attimer_sc->period);
           else
                   set_i8254_freq(MODE_STOP, 0);
   }
   
   #ifndef __amd64__
   /*
    * Restore all the timers non-atomically (XXX: should be atomically).
    *
    * This function is called from pmtimer_resume() to restore all the timers.
    * This should not be necessary, but there are broken laptops that do not
    * restore all the timers on resume. The APM spec was at best vague on the
    * subject.
    * pmtimer is used only with the old APM power management, and not with
    * acpi, which is required for amd64, so skip it in that case.
    */
   void
   timer_restore(void)
   {
   
           i8254_restore();                /* restore i8254_freq and hz */
           atrtc_restore();                /* reenable RTC interrupts */
   }
   #endif
   
   /* This is separate from startrtclock() so that it can be called early. */
   void
   i8254_init(void)
   {
   
           set_i8254_freq(MODE_STOP, 0);
   }
   
   void
   startrtclock()
   {
   
           init_TSC();
   }
   
   void
   cpu_initclocks(void)
   {
   #ifdef EARLY_AP_STARTUP
           struct thread *td;
           int i;
   
           td = curthread;
           cpu_initclocks_bsp();
           CPU_FOREACH(i) {
                   if (i == 0)
                           continue;
                   thread_lock(td);
                   sched_bind(td, i);
                   thread_unlock(td);
                   cpu_initclocks_ap();
           }
           thread_lock(td);
           if (sched_is_bound(td))
                   sched_unbind(td);
           thread_unlock(td);
   #else
           cpu_initclocks_bsp();
   #endif
   }
   
   static int
   sysctl_machdep_i8254_freq(SYSCTL_HANDLER_ARGS)
   {
           int error;
           u_int freq;
   
           /*
            * Use `i8254' instead of `timer' in external names because `timer'
            * is too generic.  Should use it everywhere.
            */
           freq = i8254_freq;
           error = sysctl_handle_int(oidp, &freq, 0, req);
           if (error == 0 && req->newptr != NULL) {
                   i8254_freq = freq;
                   if (attimer_sc != NULL) {
                           set_i8254_freq(attimer_sc->mode, attimer_sc->period);
                           attimer_sc->tc.tc_frequency = freq;
                   } else {
                           set_i8254_freq(MODE_STOP, 0);
                   }
           }
           return (error);
   }
   
   SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW,
       0, sizeof(u_int), sysctl_machdep_i8254_freq, "IU",
       "i8254 timer frequency");
   
   static unsigned
   i8254_get_timecount(struct timecounter *tc)
   {
           device_t dev = (device_t)tc->tc_priv;
           struct attimer_softc *sc = device_get_softc(dev);
           register_t flags;
           uint16_t count;
           u_int high, low;
   
           if (sc->period == 0)
                   return (i8254_max_count - getit());
   
   #ifdef __amd64__
           flags = read_rflags();
   #else
           flags = read_eflags();
   #endif
           mtx_lock_spin(&clock_lock);
   
           /* Select timer0 and latch counter value. */
           outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
   
           low = inb(TIMER_CNTR0);
           high = inb(TIMER_CNTR0);
           count = i8254_max_count - ((high << 8) | low);
           if (count < i8254_lastcount ||
               (!i8254_ticked && (clkintr_pending ||
               ((count < 20 || (!(flags & PSL_I) &&
               count < i8254_max_count / 2u)) &&
               i8254_pending != NULL && i8254_pending(i8254_intsrc))))) {
                   i8254_ticked = 1;
                   i8254_offset += i8254_max_count;
           }
           i8254_lastcount = count;
           count += i8254_offset;
           mtx_unlock_spin(&clock_lock);
           return (count);
   }
   
   static int
   attimer_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
   {
           device_t dev = (device_t)et->et_priv;
           struct attimer_softc *sc = device_get_softc(dev);
   
           if (period != 0) {
                   sc->mode = MODE_PERIODIC;
                   sc->period = period;
           } else {
                   sc->mode = MODE_ONESHOT;
                   sc->period = first;
           }
           if (!sc->intr_en) {
                   i8254_intsrc->is_pic->pic_enable_source(i8254_intsrc);
                   sc->intr_en = 1;
           }
           set_i8254_freq(sc->mode, sc->period);
           return (0);
   }
   
   static int
   attimer_stop(struct eventtimer *et)
   {
           device_t dev = (device_t)et->et_priv;
           struct attimer_softc *sc = device_get_softc(dev);
           
           sc->mode = MODE_STOP;
           sc->period = 0;
           set_i8254_freq(sc->mode, sc->period);
           return (0);
   }
   
   #ifdef DEV_ISA
   /*
    * Attach to the ISA PnP descriptors for the timer
    */
   static struct isa_pnp_id attimer_ids[] = {
           { 0x0001d041 /* PNP0100 */, "AT timer" },
           { 0 }
   };
   
   static int
   attimer_probe(device_t dev)
   {
           int result;
           
           result = ISA_PNP_PROBE(device_get_parent(dev), dev, attimer_ids);
           /* ENOENT means no PnP-ID, device is hinted. */
           if (result == ENOENT) {
                   device_set_desc(dev, "AT timer");
                   return (BUS_PROBE_LOW_PRIORITY);
           }
           return (result);
   }
   
   static int
   attimer_attach(device_t dev)
   {
           struct attimer_softc *sc;
           rman_res_t s;
           int i;
   
           attimer_sc = sc = device_get_softc(dev);
           bzero(sc, sizeof(struct attimer_softc));
           if (!(sc->port_res = bus_alloc_resource(dev, SYS_RES_IOPORT,
               &sc->port_rid, IO_TIMER1, IO_TIMER1 + 3, 4, RF_ACTIVE)))
                   device_printf(dev,"Warning: Couldn't map I/O.\n");
           i8254_intsrc = intr_lookup_source(0);
           if (i8254_intsrc != NULL)
                   i8254_pending = i8254_intsrc->is_pic->pic_source_pending;
           resource_int_value(device_get_name(dev), device_get_unit(dev),
               "timecounter", &i8254_timecounter);
           set_i8254_freq(MODE_STOP, 0);
           if (i8254_timecounter) {
                   sc->tc.tc_get_timecount = i8254_get_timecount;
                   sc->tc.tc_counter_mask = 0xffff;
                   sc->tc.tc_frequency = i8254_freq;
                   sc->tc.tc_name = "i8254";
                   sc->tc.tc_quality = 0;
                   sc->tc.tc_priv = dev;
                   tc_init(&sc->tc);
           }
           if (resource_int_value(device_get_name(dev), device_get_unit(dev),
               "clock", &i) != 0 || i != 0) {
                   sc->intr_rid = 0;
                   while (bus_get_resource(dev, SYS_RES_IRQ, sc->intr_rid,
                       &s, NULL) == 0 && s != 0)
                           sc->intr_rid++;
                   if (!(sc->intr_res = bus_alloc_resource(dev, SYS_RES_IRQ,
                       &sc->intr_rid, 0, 0, 1, RF_ACTIVE))) {
                           device_printf(dev,"Can't map interrupt.\n");
                           return (0);
                   }
                   /* Dirty hack, to make bus_setup_intr to not enable source. */
                   i8254_intsrc->is_handlers++;
                   if ((bus_setup_intr(dev, sc->intr_res,
                       INTR_MPSAFE | INTR_TYPE_CLK,
                       (driver_filter_t *)clkintr, NULL,
                       sc, &sc->intr_handler))) {
                           device_printf(dev, "Can't setup interrupt.\n");
                           i8254_intsrc->is_handlers--;
                           return (0);
                   }
                   i8254_intsrc->is_handlers--;
                   i8254_intsrc->is_pic->pic_enable_intr(i8254_intsrc);
                   sc->et.et_name = "i8254";
                   sc->et.et_flags = ET_FLAGS_PERIODIC;
                   if (!i8254_timecounter)
                           sc->et.et_flags |= ET_FLAGS_ONESHOT;
                   sc->et.et_quality = 100;
                   sc->et.et_frequency = i8254_freq;
                   sc->et.et_min_period = (0x0002LLU << 32) / i8254_freq;
                   sc->et.et_max_period = (0xfffeLLU << 32) / i8254_freq;
                   sc->et.et_start = attimer_start;
                   sc->et.et_stop = attimer_stop;
                   sc->et.et_priv = dev;
                   et_register(&sc->et);
           }
           return(0);
   }
   
   static int
   attimer_resume(device_t dev)
   {
   
           i8254_restore();
           return (0);
   }
   
   static device_method_t attimer_methods[] = {
           /* Device interface */
           DEVMETHOD(device_probe,         attimer_probe),
           DEVMETHOD(device_attach,        attimer_attach),
           DEVMETHOD(device_detach,        bus_generic_detach),
           DEVMETHOD(device_shutdown,      bus_generic_shutdown),
           DEVMETHOD(device_suspend,       bus_generic_suspend),
           DEVMETHOD(device_resume,        attimer_resume),
           { 0, 0 }
   };
   
   static driver_t attimer_driver = {
           "attimer",
           attimer_methods,
           sizeof(struct attimer_softc),
   };
   
   static devclass_t attimer_devclass;
   
   DRIVER_MODULE(attimer, isa, attimer_driver, attimer_devclass, 0, 0);
   DRIVER_MODULE(attimer, acpi, attimer_driver, attimer_devclass, 0, 0);
   ISA_PNP_INFO(attimer_ids);
   
   #endif /* DEV_ISA */

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