patch-2.4.20 linux-2.4.20/arch/x86_64/kernel/time.c
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- Lines: 446
- Date:
Thu Nov 28 15:53:12 2002
- Orig file:
linux-2.4.19/arch/x86_64/kernel/time.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -urN linux-2.4.19/arch/x86_64/kernel/time.c linux-2.4.20/arch/x86_64/kernel/time.c
@@ -0,0 +1,445 @@
+/*
+ * linux/arch/x86-64/kernel/time.c
+ *
+ * "High Precision Event Timer" based timekeeping.
+ *
+ * Copyright (c) 1991,1992,1995 Linus Torvalds
+ * Copyright (c) 1994 Alan Modra
+ * Copyright (c) 1995 Markus Kuhn
+ * Copyright (c) 1996 Ingo Molnar
+ * Copyright (c) 1998 Andrea Arcangeli
+ * Copyright (c) 2002 Vojtech Pavlik
+ *
+ */
+
+#define HPET_BIOS_SUPPORT_WORKING
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/mc146818rtc.h>
+#include <linux/irq.h>
+#include <linux/ioport.h>
+#include <asm/vsyscall.h>
+#include <asm/timex.h>
+
+extern rwlock_t xtime_lock;
+spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
+
+unsigned int cpu_khz; /* TSC clocks / usec, not used here */
+unsigned long hpet_period; /* fsecs / HPET clock */
+unsigned long hpet_tick; /* HPET clocks / interrupt */
+int hpet_report_lost_ticks; /* command line option */
+
+struct hpet_data __hpet __section_hpet; /* address, quotient, trigger, hz */
+
+volatile unsigned long __jiffies __section_jiffies;
+unsigned long __wall_jiffies __section_wall_jiffies;
+struct timeval __xtime __section_xtime;
+struct timezone __sys_tz __section_sys_tz;
+
+/*
+ * do_gettimeoffset() returns microseconds since last timer interrupt was
+ * triggered by hardware. A memory read of HPET is slower than a register read
+ * of TSC, but much more reliable. It's also synchronized to the timer
+ * interrupt. Note that do_gettimeoffset() may return more than hpet_tick, if a
+ * timer interrupt has happened already, but hpet.trigger wasn't updated yet.
+ * This is not a problem, because jiffies hasn't updated either. They are bound
+ * together by xtime_lock.
+ */
+
+static spinlock_t time_offset_lock = SPIN_LOCK_UNLOCKED;
+static unsigned long timeoffset = 0;
+
+inline unsigned int do_gettimeoffset(void)
+{
+ unsigned long t;
+ rdtscll(t);
+ return (t - hpet.last_tsc) * (1000000L / HZ) / hpet.ticks + hpet.offset;
+}
+
+/*
+ * This version of gettimeofday() has microsecond resolution and better than
+ * microsecond precision, as we're using at least a 10 MHz (usually 14.31818
+ * MHz) HPET timer.
+ */
+
+void do_gettimeofday(struct timeval *tv)
+{
+ unsigned long flags, t;
+ unsigned int sec, usec;
+
+ read_lock_irqsave(&xtime_lock, flags);
+ spin_lock(&time_offset_lock);
+
+ sec = xtime.tv_sec;
+ usec = xtime.tv_usec;
+
+ t = (jiffies - wall_jiffies) * (1000000L / HZ) + do_gettimeoffset();
+ if (t > timeoffset) timeoffset = t;
+ usec += timeoffset;
+
+ spin_unlock(&time_offset_lock);
+ read_unlock_irqrestore(&xtime_lock, flags);
+
+ tv->tv_sec = sec + usec / 1000000;
+ tv->tv_usec = usec % 1000000;
+}
+
+/*
+ * settimeofday() first undoes the correction that gettimeofday would do
+ * on the time, and then saves it. This is ugly, but has been like this for
+ * ages already.
+ */
+
+void do_settimeofday(struct timeval *tv)
+{
+ write_lock_irq(&xtime_lock);
+ vxtime_lock();
+
+ tv->tv_usec -= do_gettimeoffset() +
+ (jiffies - wall_jiffies) * tick;
+
+ while (tv->tv_usec < 0) {
+ tv->tv_usec += 1000000;
+ tv->tv_sec--;
+ }
+
+ xtime = *tv;
+ vxtime_unlock();
+
+ time_adjust = 0; /* stop active adjtime() */
+ time_status |= STA_UNSYNC;
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_esterror = NTP_PHASE_LIMIT;
+
+ write_unlock_irq(&xtime_lock);
+}
+
+/*
+ * In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500
+ * ms after the second nowtime has started, because when nowtime is written
+ * into the registers of the CMOS clock, it will jump to the next second
+ * precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data
+ * sheet for details.
+ */
+
+static void set_rtc_mmss(unsigned long nowtime)
+{
+ int real_seconds, real_minutes, cmos_minutes;
+ unsigned char control, freq_select;
+
+/*
+ * IRQs are disabled when we're called from the timer interrupt,
+ * no need for spin_lock_irqsave()
+ */
+
+ spin_lock(&rtc_lock);
+
+/*
+ * Tell the clock it's being set and stop it.
+ */
+
+ control = CMOS_READ(RTC_CONTROL);
+ CMOS_WRITE(control | RTC_SET, RTC_CONTROL);
+
+ freq_select = CMOS_READ(RTC_FREQ_SELECT);
+ CMOS_WRITE(freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT);
+
+ cmos_minutes = CMOS_READ(RTC_MINUTES);
+ BCD_TO_BIN(cmos_minutes);
+
+/*
+ * since we're only adjusting minutes and seconds, don't interfere with hour
+ * overflow. This avoids messing with unknown time zones but requires your RTC
+ * not to be off by more than 15 minutes. Since we're calling it only when
+ * our clock is externally synchronized using NTP, this shouldn't be a problem.
+ */
+
+ real_seconds = nowtime % 60;
+ real_minutes = nowtime / 60;
+ if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
+ real_minutes += 30; /* correct for half hour time zone */
+ real_minutes %= 60;
+
+ if (abs(real_minutes - cmos_minutes) < 30) {
+ BIN_TO_BCD(real_seconds);
+ BIN_TO_BCD(real_minutes);
+ CMOS_WRITE(real_seconds, RTC_SECONDS);
+ CMOS_WRITE(real_minutes, RTC_MINUTES);
+ } else
+ printk(KERN_WARNING "time.c: can't update CMOS clock from %d to %d\n",
+ cmos_minutes, real_minutes);
+
+/*
+ * The following flags have to be released exactly in this order, otherwise the
+ * DS12887 (popular MC146818A clone with integrated battery and quartz) will
+ * not reset the oscillator and will not update precisely 500 ms later. You
+ * won't find this mentioned in the Dallas Semiconductor data sheets, but who
+ * believes data sheets anyway ... -- Markus Kuhn
+ */
+
+ CMOS_WRITE(control, RTC_CONTROL);
+ CMOS_WRITE(freq_select, RTC_FREQ_SELECT);
+
+ spin_unlock(&rtc_lock);
+}
+
+static void timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ static unsigned long rtc_update = 0;
+
+/*
+ * Here we are in the timer irq handler. We have irqs locally disabled (so we
+ * don't need spin_lock_irqsave()) but we don't know if the timer_bh is running
+ * on the other CPU, so we need a lock. We also need to lock the vsyscall
+ * variables, because both do_timer() and us change them -arca+vojtech
+ */
+
+ write_lock(&xtime_lock);
+ vxtime_lock();
+
+ {
+ unsigned long t;
+
+ rdtscll(t);
+ hpet.offset = (t - hpet.last_tsc) * (1000000L / HZ) / hpet.ticks + hpet.offset - 1000000L / HZ;
+ if (hpet.offset >= 1000000L / HZ)
+ hpet.offset = 0;
+ hpet.ticks = min_t(long, max_t(long, (t - hpet.last_tsc) * (1000000L / HZ) / (1000000L / HZ - hpet.offset),
+ cpu_khz * 1000/HZ * 15 / 16), cpu_khz * 1000/HZ * 16 / 15);
+ hpet.last_tsc = t;
+ }
+
+/*
+ * Do the timer stuff.
+ */
+
+ do_timer(regs);
+
+/*
+ * If we have an externally synchronized Linux clock, then update CMOS clock
+ * accordingly every ~11 minutes. set_rtc_mmss() will be called in the jiffy
+ * closest to exactly 500 ms before the next second. If the update fails, we
+ * don'tcare, as it'll be updated on the next turn, and the problem (time way
+ * off) isn't likely to go away much sooner anyway.
+ */
+
+ if ((~time_status & STA_UNSYNC) && xtime.tv_sec > rtc_update &&
+ abs(xtime.tv_usec - 500000) <= tick / 2) {
+ set_rtc_mmss(xtime.tv_sec);
+ rtc_update = xtime.tv_sec + 660;
+ }
+
+ vxtime_unlock();
+ write_unlock(&xtime_lock);
+}
+
+static unsigned long get_cmos_time(void)
+{
+ unsigned int timeout, year, mon, day, hour, min, sec;
+ unsigned char last, this;
+
+/*
+ * The Linux interpretation of the CMOS clock register contents: When the
+ * Update-In-Progress (UIP) flag goes from 1 to 0, the RTC registers show the
+ * second which has precisely just started. Waiting for this can take up to 1
+ * second, we timeout approximately after 2.4 seconds on a machine with
+ * standard 8.3 MHz ISA bus.
+ */
+
+ spin_lock(&rtc_lock);
+
+ timeout = 1000000;
+ last = this = 0;
+
+ while (timeout && last && !this) {
+ last = this;
+ this = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP;
+ timeout--;
+ }
+
+/*
+ * Here we are safe to assume the registers won't change for a whole second, so
+ * we just go ahead and read them.
+ */
+
+ sec = CMOS_READ(RTC_SECONDS);
+ min = CMOS_READ(RTC_MINUTES);
+ hour = CMOS_READ(RTC_HOURS);
+ day = CMOS_READ(RTC_DAY_OF_MONTH);
+ mon = CMOS_READ(RTC_MONTH);
+ year = CMOS_READ(RTC_YEAR);
+
+ spin_unlock(&rtc_lock);
+
+/*
+ * We know that x86-64 always uses BCD format, no need to check the config
+ * register.
+ */
+
+ BCD_TO_BIN(sec);
+ BCD_TO_BIN(min);
+ BCD_TO_BIN(hour);
+ BCD_TO_BIN(day);
+ BCD_TO_BIN(mon);
+ BCD_TO_BIN(year);
+
+/*
+ * This will work up to Dec 31, 2069.
+ */
+
+ if ((year += 1900) < 1970)
+ year += 100;
+
+ return mktime(year, mon, day, hour, min, sec);
+}
+
+/*
+ * calibrate_tsc() calibrates the processor TSC in a very simple way, comparing
+ * it to the HPET timer of known frequency.
+ */
+
+#define TICK_COUNT 100000000
+
+static unsigned int __init hpet_calibrate_tsc(void)
+{
+ int tsc_start, hpet_start;
+ int tsc_now, hpet_now;
+ unsigned long flags;
+
+ __save_flags(flags);
+ __cli();
+
+ hpet_start = hpet_readl(HPET_COUNTER);
+ rdtscl(tsc_start);
+
+ do {
+ __cli();
+ hpet_now = hpet_readl(HPET_COUNTER);
+ rdtscl(tsc_now);
+ __restore_flags(flags);
+ } while ((tsc_now - tsc_start) < TICK_COUNT && (hpet_now - hpet_start) < TICK_COUNT);
+
+ return (tsc_now - tsc_start) * 1000000000L
+ / ((hpet_now - hpet_start) * hpet_period / 1000);
+}
+
+/*
+ * pit_calibrate_tsc() uses the speaker output (channel 2) of
+ * the PIT. This is better than using the timer interrupt output,
+ * because we can read the value of the speaker with just one inb(),
+ * where we need three i/o operations for the interrupt channel.
+ * We count how many ticks the TSC does in 50 ms.
+ */
+
+static unsigned int __init pit_calibrate_tsc(void)
+{
+ unsigned long start, end;
+ unsigned long flags;
+
+ outb((inb(0x61) & ~0x02) | 0x01, 0x61);
+
+ __save_flags(flags);
+ __cli();
+
+ outb(0xb0, 0x43);
+ outb((1193182 / (1000 / 50)) & 0xff, 0x42);
+ outb((1193182 / (1000 / 50)) >> 8, 0x42);
+ rdtscll(start);
+
+ while ((inb(0x61) & 0x20) == 0);
+ rdtscll(end);
+
+ __restore_flags(flags);
+
+ return (end - start) / 50;
+}
+
+static int hpet_init(void)
+{
+ unsigned int cfg, id;
+
+ if (!hpet.address)
+ return -1;
+ set_fixmap_nocache(FIX_HPET_BASE, hpet.address);
+
+/*
+ * Read the period, compute tick and quotient.
+ */
+
+ id = hpet_readl(HPET_ID);
+
+ if (!(id & HPET_ID_VENDOR) || !(id & HPET_ID_NUMBER) || !(id & HPET_ID_LEGSUP))
+ return -1;
+
+ hpet_period = hpet_readl(HPET_PERIOD);
+ if (hpet_period < 100000 || hpet_period > 100000000)
+ return -1;
+
+ hpet_tick = (1000000000L * tick + hpet_period / 2) / hpet_period;
+
+/*
+ * Stop the timers and reset the main counter.
+ */
+
+ cfg = hpet_readl(HPET_CFG);
+ cfg &= ~(HPET_CFG_ENABLE | HPET_CFG_LEGACY);
+ hpet_writel(cfg, HPET_CFG);
+ hpet_writel(0, HPET_COUNTER);
+ hpet_writel(0, HPET_COUNTER + 4);
+
+/*
+ * Set up timer 0, as periodic with first interrupt to happen at hpet_tick,
+ * and period also hpet_tick.
+ */
+
+ hpet_writel(HPET_T0_ENABLE | HPET_T0_PERIODIC | HPET_T0_SETVAL | HPET_T0_32BIT, HPET_T0_CFG);
+ hpet_writel(hpet_tick, HPET_T0_CMP);
+ hpet_writel(hpet_tick, HPET_T0_CMP);
+
+/*
+ * Go!
+ */
+
+ cfg |= HPET_CFG_ENABLE | HPET_CFG_LEGACY;
+ hpet_writel(cfg, HPET_CFG);
+
+ return 0;
+}
+
+void __init pit_init(void)
+{
+ outb_p(0x34, 0x43); /* binary, mode 2, LSB/MSB, ch 0 */
+ outb_p(LATCH & 0xff, 0x40); /* LSB */
+ outb_p(LATCH >> 8, 0x40); /* MSB */
+}
+
+int __init time_setup(char *str)
+{
+ hpet_report_lost_ticks = 1;
+ return 1;
+}
+
+static struct irqaction irq0 = { timer_interrupt, SA_INTERRUPT, 0, "timer", NULL, NULL};
+
+extern void __init config_acpi_tables(void);
+
+void __init time_init(void)
+{
+ xtime.tv_sec = get_cmos_time();
+ xtime.tv_usec = 0;
+
+ printk(KERN_WARNING "time.c: HPET timer not found, precise timing unavailable.\n");
+ pit_init();
+ printk(KERN_INFO "time.c: Using 1.1931816 MHz PIT timer.\n");
+ setup_irq(0, &irq0);
+ cpu_khz = pit_calibrate_tsc();
+ printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
+ cpu_khz / 1000, cpu_khz % 1000);
+ hpet.ticks = cpu_khz * (1000 / HZ);
+ rdtscll(hpet.last_tsc);
+}
+
+__setup("report_lost_ticks", time_setup);
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