/*- * Copyright (c) 1990 The Regents of the University of California. * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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 * $Id$ */ /* * Routines to handle clock hardware. */ /* * inittodr, settodr and support routines written * by Christoph Robitschko * * reintroduced and updated by Chris Stenton 8/10/94 */ #include "opt_clock.h" #include "opt_cpu.h" #include #include #include #include #include #include #ifdef CLK_CALIBRATION_LOOP #include #endif #include #include #include #include #include #include #include /* * 32-bit time_t's can't reach leap years before 1904 or after 2036, so we * can use a simple formula for leap years. */ #define LEAPYEAR(y) ((u_int)(y) % 4 == 0) #define DAYSPERYEAR (31+28+31+30+31+30+31+31+30+31+30+31) #define TIMER_DIV(x) ((timer_freq + (x) / 2) / (x)) /* * Time in timer cycles that it takes for microtime() to disable interrupts * and latch the count. microtime() currently uses "cli; outb ..." so it * normally takes less than 2 timer cycles. Add a few for cache misses. * Add a few more to allow for latency in bogus calls to microtime() with * interrupts already disabled. */ #define TIMER0_LATCH_COUNT 20 /* * Maximum frequency that we are willing to allow for timer0. Must be * low enough to guarantee that the timer interrupt handler returns * before the next timer interrupt. Must result in a lower TIMER_DIV * value than TIMER0_LATCH_COUNT so that we don't have to worry about * underflow in the calculation of timer0_overflow_threshold. */ #define TIMER0_MAX_FREQ 20000 int adjkerntz; /* local offset from GMT in seconds */ int disable_rtc_set; /* disable resettodr() if != 0 */ u_int idelayed; #if defined(I586_CPU) || defined(I686_CPU) u_int i586_ctr_bias; u_int i586_ctr_comultiplier; u_int i586_ctr_freq; u_int i586_ctr_multiplier; #endif int statclock_disable; u_int stat_imask = SWI_CLOCK_MASK; #ifdef TIMER_FREQ u_int timer_freq = TIMER_FREQ; #else u_int timer_freq = 1193182; #endif int timer0_max_count; u_int timer0_overflow_threshold; u_int timer0_prescaler_count; int wall_cmos_clock; /* wall CMOS clock assumed if != 0 */ static int beeping = 0; static u_int clk_imask = HWI_MASK | SWI_MASK; static const u_char daysinmonth[] = {31,28,31,30,31,30,31,31,30,31,30,31}; static u_int hardclock_max_count; /* * XXX new_function and timer_func should not handle clockframes, but * timer_func currently needs to hold hardclock to handle the * timer0_state == 0 case. We should use register_intr()/unregister_intr() * to switch between clkintr() and a slightly different timerintr(). */ static void (*new_function) __P((struct clockframe *frame)); static u_int new_rate; static u_char rtc_statusa = RTCSA_DIVIDER | RTCSA_NOPROF; static u_char rtc_statusb = RTCSB_24HR | RTCSB_PINTR; /* Values for timerX_state: */ #define RELEASED 0 #define RELEASE_PENDING 1 #define ACQUIRED 2 #define ACQUIRE_PENDING 3 static u_char timer0_state; static u_char timer2_state; static void (*timer_func) __P((struct clockframe *frame)) = hardclock; #if defined(I586_CPU) || defined(I686_CPU) static void set_i586_ctr_freq(u_int i586_freq, u_int i8254_freq); #endif static void set_timer_freq(u_int freq, int intr_freq); static void clkintr(struct clockframe frame) { timer_func(&frame); switch (timer0_state) { case RELEASED: setdelayed(); break; case ACQUIRED: if ((timer0_prescaler_count += timer0_max_count) >= hardclock_max_count) { hardclock(&frame); setdelayed(); timer0_prescaler_count -= hardclock_max_count; } break; case ACQUIRE_PENDING: setdelayed(); timer0_max_count = TIMER_DIV(new_rate); timer0_overflow_threshold = timer0_max_count - TIMER0_LATCH_COUNT; disable_intr(); outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT); outb(TIMER_CNTR0, timer0_max_count & 0xff); outb(TIMER_CNTR0, timer0_max_count >> 8); enable_intr(); timer0_prescaler_count = 0; timer_func = new_function; timer0_state = ACQUIRED; break; case RELEASE_PENDING: if ((timer0_prescaler_count += timer0_max_count) >= hardclock_max_count) { hardclock(&frame); setdelayed(); timer0_max_count = hardclock_max_count; timer0_overflow_threshold = timer0_max_count - TIMER0_LATCH_COUNT; disable_intr(); outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT); outb(TIMER_CNTR0, timer0_max_count & 0xff); outb(TIMER_CNTR0, timer0_max_count >> 8); enable_intr(); /* * See microtime.s for this magic. */ time.tv_usec += (27465 * (timer0_prescaler_count - hardclock_max_count)) >> 15; if (time.tv_usec >= 1000000) time.tv_usec -= 1000000; timer0_prescaler_count = 0; timer_func = hardclock; timer0_state = RELEASED; } break; } } /* * The acquire and release functions must be called at ipl >= splclock(). */ int acquire_timer0(int rate, void (*function) __P((struct clockframe *frame))) { static int old_rate; if (rate <= 0 || rate > TIMER0_MAX_FREQ) return (-1); switch (timer0_state) { case RELEASED: timer0_state = ACQUIRE_PENDING; break; case RELEASE_PENDING: if (rate != old_rate) return (-1); /* * The timer has been released recently, but is being * re-acquired before the release completed. In this * case, we simply reclaim it as if it had not been * released at all. */ timer0_state = ACQUIRED; break; default: return (-1); /* busy */ } new_function = function; old_rate = new_rate = rate; return (0); } int acquire_timer2(int mode) { 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)); return (0); } int release_timer0() { switch (timer0_state) { case ACQUIRED: timer0_state = RELEASE_PENDING; break; case ACQUIRE_PENDING: /* Nothing happened yet, release quickly. */ timer0_state = RELEASED; break; default: return (-1); } return (0); } int release_timer2() { if (timer2_state != ACQUIRED) return (-1); timer2_state = RELEASED; outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT); return (0); } /* * This routine receives statistical clock interrupts from the RTC. * As explained above, these occur at 128 interrupts per second. * When profiling, we receive interrupts at a rate of 1024 Hz. * * This does not actually add as much overhead as it sounds, because * when the statistical clock is active, the hardclock driver no longer * needs to keep (inaccurate) statistics on its own. This decouples * statistics gathering from scheduling interrupts. * * The RTC chip requires that we read status register C (RTC_INTR) * to acknowledge an interrupt, before it will generate the next one. */ static void rtcintr(struct clockframe frame) { u_char stat; stat = rtcin(RTC_INTR); if(stat & RTCIR_PERIOD) { statclock(&frame); } } #include "opt_ddb.h" #ifdef DDB #include DB_SHOW_COMMAND(rtc, rtc) { printf("%02x/%02x/%02x %02x:%02x:%02x, A = %02x, B = %02x, C = %02x\n", rtcin(RTC_YEAR), rtcin(RTC_MONTH), rtcin(RTC_DAY), rtcin(RTC_HRS), rtcin(RTC_MIN), rtcin(RTC_SEC), rtcin(RTC_STATUSA), rtcin(RTC_STATUSB), rtcin(RTC_INTR)); } #endif /* DDB */ static int getit(void) { u_long ef; int high, low; ef = read_eflags(); disable_intr(); /* Select timer0 and latch counter value. */ outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH); low = inb(TIMER_CNTR0); high = inb(TIMER_CNTR0); write_eflags(ef); return ((high << 8) | low); } /* * Wait "n" microseconds. * Relies on timer 1 counting down from (timer_freq / hz) * Note: timer had better have been programmed before this is first used! */ void 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 /* * Guard against the timer being uninitialized if we are called * early for console i/o. */ if (timer0_max_count == 0) set_timer_freq(timer_freq, hz); /* * 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). */ prev_tick = getit(); n -= 0; /* XXX actually guess no initial overhead */ /* * Calculate (n * (timer_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)timer_freq + 999999) / 1000000; while (ticks_left > 0) { tick = getit(); #ifdef DELAYDEBUG ++getit_calls; #endif delta = prev_tick - tick; prev_tick = tick; if (delta < 0) { delta += timer0_max_count; /* * Guard against timer0_max_count being wrong. * This shouldn't happen in normal operation, * but it may happen if set_timer_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 sysbeepstop(void *chan) { outb(IO_PPI, inb(IO_PPI)&0xFC); /* disable counter2 output to speaker */ release_timer2(); beeping = 0; } int sysbeep(int pitch, int period) { int x = splclock(); if (acquire_timer2(TIMER_SQWAVE|TIMER_16BIT)) if (!beeping) { /* Something else owns it. */ splx(x); return (-1); /* XXX Should be EBUSY, but nobody cares anyway. */ } disable_intr(); outb(TIMER_CNTR2, pitch); outb(TIMER_CNTR2, (pitch>>8)); enable_intr(); if (!beeping) { /* enable counter2 output to speaker */ outb(IO_PPI, inb(IO_PPI) | 3); beeping = period; timeout(sysbeepstop, (void *)NULL, period); } splx(x); return (0); } /* * RTC support routines */ int rtcin(reg) int reg; { u_char val; outb(IO_RTC, reg); inb(0x84); val = inb(IO_RTC + 1); inb(0x84); return (val); } static __inline void writertc(u_char reg, u_char val) { outb(IO_RTC, reg); outb(IO_RTC + 1, val); } static __inline int readrtc(int port) { return(bcd2bin(rtcin(port))); } static u_int calibrate_clocks(void) { u_int count, prev_count, tot_count; int sec, start_sec, timeout; printf("Calibrating clock(s) relative to mc146818A clock ... "); if (!(rtcin(RTC_STATUSD) & RTCSD_PWR)) goto fail; timeout = 100000000; /* Read the mc146818A seconds counter. */ for (;;) { if (!(rtcin(RTC_STATUSA) & RTCSA_TUP)) { sec = rtcin(RTC_SEC); break; } if (--timeout == 0) goto fail; } /* Wait for the mC146818A seconds counter to change. */ start_sec = sec; for (;;) { if (!(rtcin(RTC_STATUSA) & RTCSA_TUP)) { sec = rtcin(RTC_SEC); if (sec != start_sec) break; } if (--timeout == 0) goto fail; } /* Start keeping track of the i8254 counter. */ prev_count = getit(); if (prev_count == 0 || prev_count > timer0_max_count) goto fail; tot_count = 0; #if defined(I586_CPU) || defined(I686_CPU) if (cpu_class == CPUCLASS_586 || cpu_class == CPUCLASS_686) wrmsr(0x10, 0LL); /* XXX 0x10 is the MSR for the TSC */ #endif /* * Wait for the mc146818A seconds counter to change. Read the i8254 * counter for each iteration since this is convenient and only * costs a few usec of inaccuracy. The timing of the final reads * of the counters almost matches the timing of the initial reads, * so the main cause of inaccuracy is the varying latency from * inside getit() or rtcin(RTC_STATUSA) to the beginning of the * rtcin(RTC_SEC) that returns a changed seconds count. The * maximum inaccuracy from this cause is < 10 usec on 486's. */ start_sec = sec; for (;;) { if (!(rtcin(RTC_STATUSA) & RTCSA_TUP)) sec = rtcin(RTC_SEC); count = getit(); if (count == 0 || count > timer0_max_count) goto fail; if (count > prev_count) tot_count += prev_count - (count - timer0_max_count); else tot_count += prev_count - count; prev_count = count; if (sec != start_sec) break; if (--timeout == 0) goto fail; } #if defined(I586_CPU) || defined(I686_CPU) /* * Read the cpu cycle counter. The timing considerations are * similar to those for the i8254 clock. */ if (cpu_class == CPUCLASS_586 || cpu_class == CPUCLASS_686) { set_i586_ctr_freq((u_int)rdtsc(), tot_count); printf("i586 clock: %u Hz, ", i586_ctr_freq); } #endif printf("i8254 clock: %u Hz\n", tot_count); return (tot_count); fail: printf("failed, using default i8254 clock of %u Hz\n", timer_freq); return (timer_freq); } static void set_timer_freq(u_int freq, int intr_freq) { u_long ef; ef = read_eflags(); disable_intr(); timer_freq = freq; timer0_max_count = hardclock_max_count = TIMER_DIV(intr_freq); timer0_overflow_threshold = timer0_max_count - TIMER0_LATCH_COUNT; outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT); outb(TIMER_CNTR0, timer0_max_count & 0xff); outb(TIMER_CNTR0, timer0_max_count >> 8); write_eflags(ef); } /* * Initialize 8253 timer 0 early so that it can be used in DELAY(). * XXX initialization of other timers is unintentionally left blank. */ void startrtclock() { u_int delta, freq; writertc(RTC_STATUSA, rtc_statusa); writertc(RTC_STATUSB, RTCSB_24HR); set_timer_freq(timer_freq, hz); freq = calibrate_clocks(); #ifdef CLK_CALIBRATION_LOOP if (bootverbose) { printf( "Press a key on the console to abort clock calibration\n"); while (cncheckc() == -1) calibrate_clocks(); } #endif /* * Use the calibrated i8254 frequency if it seems reasonable. * Otherwise use the default, and don't use the calibrated i586 * frequency. */ delta = freq > timer_freq ? freq - timer_freq : timer_freq - freq; if (delta < timer_freq / 100) { #ifndef CLK_USE_I8254_CALIBRATION if (bootverbose) printf( "CLK_USE_I8254_CALIBRATION not specified - using default frequency\n"); freq = timer_freq; #endif timer_freq = freq; } else { printf("%d Hz differs from default of %d Hz by more than 1%%\n", freq, timer_freq); #if defined(I586_CPU) || defined(I686_CPU) i586_ctr_freq = 0; #endif } set_timer_freq(timer_freq, hz); #if defined(I586_CPU) || defined(I686_CPU) #ifndef CLK_USE_I586_CALIBRATION if (i586_ctr_freq != 0) { if (bootverbose) printf( "CLK_USE_I586_CALIBRATION not specified - using old calibration method\n"); i586_ctr_freq = 0; } #endif if (i586_ctr_freq == 0 && (cpu_class == CPUCLASS_586 || cpu_class == CPUCLASS_686)) { /* * Calibration of the i586 clock relative to the mc146818A * clock failed. Do a less accurate calibration relative * to the i8254 clock. */ wrmsr(0x10, 0LL); /* XXX */ DELAY(1000000); set_i586_ctr_freq((u_int)rdtsc(), timer_freq); #ifdef CLK_USE_I586_CALIBRATION printf("i586 clock: %u Hz\n", i586_ctr_freq); #endif } #endif } /* * Initialize the time of day register, based on the time base which is, e.g. * from a filesystem. */ void inittodr(time_t base) { unsigned long sec, days; int yd; int year, month; int y, m, s; s = splclock(); time.tv_sec = base; time.tv_usec = 0; splx(s); /* Look if we have a RTC present and the time is valid */ if (!(rtcin(RTC_STATUSD) & RTCSD_PWR)) goto wrong_time; /* wait for time update to complete */ /* If RTCSA_TUP is zero, we have at least 244us before next update */ while (rtcin(RTC_STATUSA) & RTCSA_TUP); days = 0; #ifdef USE_RTC_CENTURY year = readrtc(RTC_YEAR) + readrtc(RTC_CENTURY) * 100; #else year = readrtc(RTC_YEAR) + 1900; if (year < 1970) year += 100; #endif if (year < 1970) goto wrong_time; month = readrtc(RTC_MONTH); for (m = 1; m < month; m++) days += daysinmonth[m-1]; if ((month > 2) && LEAPYEAR(year)) days ++; days += readrtc(RTC_DAY) - 1; yd = days; for (y = 1970; y < year; y++) days += DAYSPERYEAR + LEAPYEAR(y); sec = ((( days * 24 + readrtc(RTC_HRS)) * 60 + readrtc(RTC_MIN)) * 60 + readrtc(RTC_SEC)); /* sec now contains the number of seconds, since Jan 1 1970, in the local time zone */ sec += tz.tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0); s = splclock(); time.tv_sec = sec; splx(s); return; wrong_time: printf("Invalid time in real time clock.\n"); printf("Check and reset the date immediately!\n"); } /* * Write system time back to RTC */ void resettodr() { unsigned long tm; int y, m, s; if (disable_rtc_set) return; s = splclock(); tm = time.tv_sec; splx(s); /* Disable RTC updates and interrupts. */ writertc(RTC_STATUSB, RTCSB_HALT | RTCSB_24HR); /* Calculate local time to put in RTC */ tm -= tz.tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0); writertc(RTC_SEC, bin2bcd(tm%60)); tm /= 60; /* Write back Seconds */ writertc(RTC_MIN, bin2bcd(tm%60)); tm /= 60; /* Write back Minutes */ writertc(RTC_HRS, bin2bcd(tm%24)); tm /= 24; /* Write back Hours */ /* We have now the days since 01-01-1970 in tm */ writertc(RTC_WDAY, (tm+4)%7); /* Write back Weekday */ for (y = 1970, m = DAYSPERYEAR + LEAPYEAR(y); tm >= m; y++, m = DAYSPERYEAR + LEAPYEAR(y)) tm -= m; /* Now we have the years in y and the day-of-the-year in tm */ writertc(RTC_YEAR, bin2bcd(y%100)); /* Write back Year */ #ifdef USE_RTC_CENTURY writertc(RTC_CENTURY, bin2bcd(y/100)); /* ... and Century */ #endif for (m = 0; ; m++) { int ml; ml = daysinmonth[m]; if (m == 1 && LEAPYEAR(y)) ml++; if (tm < ml) break; tm -= ml; } writertc(RTC_MONTH, bin2bcd(m + 1)); /* Write back Month */ writertc(RTC_DAY, bin2bcd(tm + 1)); /* Write back Month Day */ /* Reenable RTC updates and interrupts. */ writertc(RTC_STATUSB, rtc_statusb); } /* * Start both clocks running. */ void cpu_initclocks() { int diag; if (statclock_disable) { /* * The stat interrupt mask is different without the * statistics clock. Also, don't set the interrupt * flag which would normally cause the RTC to generate * interrupts. */ stat_imask = HWI_MASK | SWI_MASK; rtc_statusb = RTCSB_24HR; } else { /* Setting stathz to nonzero early helps avoid races. */ stathz = RTC_NOPROFRATE; profhz = RTC_PROFRATE; } /* Finish initializing 8253 timer 0. */ register_intr(/* irq */ 0, /* XXX id */ 0, /* flags */ 0, /* XXX */ (inthand2_t *)clkintr, &clk_imask, /* unit */ 0); INTREN(IRQ0); #if defined(I586_CPU) || defined(I686_CPU) /* * Finish setting up anti-jitter measures. */ if (i586_ctr_freq != 0) i586_ctr_bias = rdtsc(); #endif /* Initialize RTC. */ writertc(RTC_STATUSA, rtc_statusa); writertc(RTC_STATUSB, RTCSB_24HR); /* Don't bother enabling the statistics clock. */ if (statclock_disable) return; diag = rtcin(RTC_DIAG); if (diag != 0) printf("RTC BIOS diagnostic error %b\n", diag, RTCDG_BITS); register_intr(/* irq */ 8, /* XXX id */ 1, /* flags */ 0, /* XXX */ (inthand2_t *)rtcintr, &stat_imask, /* unit */ 0); INTREN(IRQ8); writertc(RTC_STATUSB, rtc_statusb); } void setstatclockrate(int newhz) { if (newhz == RTC_PROFRATE) rtc_statusa = RTCSA_DIVIDER | RTCSA_PROF; else rtc_statusa = RTCSA_DIVIDER | RTCSA_NOPROF; writertc(RTC_STATUSA, rtc_statusa); } 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 is too generic. Should use it everywhere. */ freq = timer_freq; error = sysctl_handle_opaque(oidp, &freq, sizeof freq, req); if (error == 0 && req->newptr != NULL) { if (timer0_state != 0) return (EBUSY); /* too much trouble to handle */ set_timer_freq(freq, hz); #if defined(I586_CPU) || defined(I686_CPU) set_i586_ctr_freq(i586_ctr_freq, timer_freq); #endif } return (error); } SYSCTL_PROC(_machdep, OID_AUTO, i8254_freq, CTLTYPE_INT | CTLFLAG_RW, 0, sizeof(u_int), sysctl_machdep_i8254_freq, "I", ""); #if defined(I586_CPU) || defined(I686_CPU) static void set_i586_ctr_freq(u_int i586_freq, u_int i8254_freq) { u_int comultiplier, multiplier; u_long ef; if (i586_freq == 0) { i586_ctr_freq = i586_freq; return; } comultiplier = ((unsigned long long)i586_freq << I586_CTR_COMULTIPLIER_SHIFT) / i8254_freq; multiplier = (1000000LL << I586_CTR_MULTIPLIER_SHIFT) / i586_freq; ef = read_eflags(); disable_intr(); i586_ctr_freq = i586_freq; i586_ctr_comultiplier = comultiplier; i586_ctr_multiplier = multiplier; write_eflags(ef); } static int sysctl_machdep_i586_freq SYSCTL_HANDLER_ARGS { int error; u_int freq; if (cpu_class != CPUCLASS_586 && cpu_class != CPUCLASS_686) return (EOPNOTSUPP); freq = i586_ctr_freq; error = sysctl_handle_opaque(oidp, &freq, sizeof freq, req); if (error == 0 && req->newptr != NULL) set_i586_ctr_freq(freq, timer_freq); return (error); } SYSCTL_PROC(_machdep, OID_AUTO, i586_freq, CTLTYPE_INT | CTLFLAG_RW, 0, sizeof(u_int), sysctl_machdep_i586_freq, "I", ""); #endif /* defined(I586_CPU) || defined(I686_CPU) */