patch-2.1.48 linux/arch/ppc/kernel/prep_time.c

• Lines: 316
• Date: Thu Jul 31 13:09:17 1997
• Orig file: v2.1.47/linux/arch/ppc/kernel/prep_time.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.47/linux/arch/ppc/kernel/prep_time.c linux/arch/ppc/kernel/prep_time.c
@@ -0,0 +1,315 @@
+/*
+ *  linux/arch/i386/kernel/time.c
+ *
+ *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
+ *
+ * Adapted for PowerPC (PreP) by Gary Thomas
+ * Modified by Cort Dougan (cort@cs.nmt.edu)
+ *  copied and modified from intel version
+ *
+ */
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/timex.h>
+#include <linux/kernel_stat.h>
+#include <linux/mc146818rtc.h>
+
+#include <asm/segment.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+
+/* last time the cmos clock got updated */
+static long last_rtc_update = 0;
+static int set_rtc_mmss(unsigned long nowtime);
+unsigned long get_cmos_time(void);
+static inline unsigned long mktime(unsigned int, unsigned int,unsigned int,
+				   unsigned int, unsigned int, unsigned int);
+#define TIMER_IRQ 0
+
+/* Cycle counter value at the previous timer interrupt.. */
+static unsigned long long last_timer_cc = 0;
+static unsigned long long init_timer_cc = 0;
+
+#define TICK_SIZE tick
+#define FEBRUARY	2
+#define	STARTOFTIME	1970
+#define SECDAY		86400L
+#define SECYR		(SECDAY * 365)
+#define	leapyear(year)		((year) % 4 == 0)
+#define	days_in_year(a) 	(leapyear(a) ? 366 : 365)
+#define	days_in_month(a) 	(month_days[(a) - 1])
+
+static int      month_days[12] = {
+	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+};
+
+static unsigned long do_slow_gettimeoffset(void)
+{
+	int count;
+	unsigned long offset = 0;
+
+	/* timer count may underflow right here */
+	outb_p(0x00, 0x43);	/* latch the count ASAP */
+	count = inb_p(0x40);	/* read the latched count */
+	count |= inb(0x40) << 8;
+	/* we know probability of underflow is always MUCH less than 1% */
+	if (count > (LATCH - LATCH/100)) {
+		/* check for pending timer interrupt */
+		outb_p(0x0a, 0x20);
+		if (inb(0x20) & 1)
+			offset = TICK_SIZE;
+	}
+	count = ((LATCH-1) - count) * TICK_SIZE;
+	count = (count + LATCH/2) / LATCH;
+	return offset + count;
+}
+
+static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset;
+
+/*
+ * This version of gettimeofday has near microsecond resolution.
+ */
+void do_gettimeofday(struct timeval *tv)
+{
+	unsigned long flags;
+	save_flags(flags);
+	cli();
+	*tv = xtime;
+	tv->tv_usec += do_gettimeoffset();
+	if (tv->tv_usec >= 1000000) {
+		tv->tv_usec -= 1000000;
+		tv->tv_sec++;
+	}
+	restore_flags(flags);
+}
+
+void do_settimeofday(struct timeval *tv)
+{
+	cli();
+	tv->tv_usec -= do_gettimeoffset();
+  
+	if (tv->tv_usec < 0) {
+		tv->tv_usec += 1000000;
+		tv->tv_sec--;
+	}
+  
+	xtime = *tv;
+	time_state = TIME_ERROR;
+	time_maxerror = 0x70000000;
+	time_esterror = 0x70000000;
+	sti();
+}
+
+void to_tm(int tim, struct rtc_time * tm)
+{
+	register int    i;
+	register long   hms, day;
+
+	day = tim / SECDAY;
+	hms = tim % SECDAY;
+
+	/* Hours, minutes, seconds are easy */
+	tm->tm_hour = hms / 3600;
+	tm->tm_min = (hms % 3600) / 60;
+	tm->tm_sec = (hms % 3600) % 60;
+
+	/* Number of years in days */
+	for (i = STARTOFTIME; day >= days_in_year(i); i++)
+		day -= days_in_year(i);
+	tm->tm_year = i;
+
+	/* Number of months in days left */
+	if (leapyear(tm->tm_year))
+		days_in_month(FEBRUARY) = 29;
+	for (i = 1; day >= days_in_month(i); i++)
+		day -= days_in_month(i);
+	days_in_month(FEBRUARY) = 28;
+	tm->tm_mon = i;
+
+	/* Days are what is left over (+1) from all that. */
+	tm->tm_mday = day + 1;
+}
+
+/*
+ * Set the hardware clock. -- Cort
+ */
+static int set_rtc_mmss(unsigned long nowtime)
+{
+	int retval = 0;
+	int real_seconds, real_minutes, cmos_minutes;
+	unsigned char save_control, save_freq_select;
+	struct rtc_time tm;
+
+	to_tm(nowtime, &tm);
+
+	save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
+	CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
+
+	save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
+	CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
+
+        tm.tm_year -= 1900;
+	if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+		BIN_TO_BCD(tm.tm_sec);
+		BIN_TO_BCD(tm.tm_min);
+		BIN_TO_BCD(tm.tm_hour);
+		BIN_TO_BCD(tm.tm_mon);
+		BIN_TO_BCD(tm.tm_mday);
+		BIN_TO_BCD(tm.tm_year);
+	}
+	CMOS_WRITE(tm.tm_sec,RTC_SECONDS);
+	CMOS_WRITE(tm.tm_min,RTC_MINUTES);
+	CMOS_WRITE(tm.tm_hour,RTC_HOURS);
+	CMOS_WRITE(tm.tm_mon,RTC_MONTH);
+	CMOS_WRITE(tm.tm_mday,RTC_DAY_OF_MONTH);
+	CMOS_WRITE(tm.tm_year,RTC_YEAR);
+	
+	/* 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(save_control, RTC_CONTROL);
+	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+
+	if ( (time_state == TIME_ERROR) || (time_state == TIME_BAD) )
+		time_state = TIME_OK;
+	return 0;
+}
+
+unsigned long get_cmos_time(void)
+{
+	unsigned int year, mon, day, hour, min, sec;
+	int i;
+
+	/* 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.
+	 * Let's hope other operating systems interpret the RTC the same way.
+	 */
+	/* read RTC exactly on falling edge of update flag */
+	for (i = 0 ; i < 1000000 ; i++)	/* may take up to 1 second... */
+		if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
+			break;
+	for (i = 0 ; i < 1000000 ; i++)	/* must try at least 2.228 ms */
+		if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+			break;
+	do { /* Isn't this overkill ? UIP above should guarantee consistency */
+		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);
+	} while (sec != CMOS_READ(RTC_SECONDS));
+	if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+	  {
+	    BCD_TO_BIN(sec);
+	    BCD_TO_BIN(min);
+	    BCD_TO_BIN(hour);
+	    BCD_TO_BIN(day);
+	    BCD_TO_BIN(mon);
+	    BCD_TO_BIN(year);
+	  }
+	if ((year += 1900) < 1970)
+		year += 100;
+	return mktime(year, mon, day, hour, min, sec);
+}
+
+/*
+ * timer_interrupt() needs to keep up the real-time clock,
+ * as well as call the "do_timer()" routine every clocktick
+ */
+static inline void timer_interrupt(int irq, void *dev, struct pt_regs * regs)
+{
+	do_timer(regs);
+
+	/* update the hw clock if:
+	 * the time is marked out of sync (TIME_ERROR)
+	 * or ~11 minutes have expired since the last update -- Cort
+	 * If we have an externally synchronized Linux clock, then update
+	 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
+	 * called as close as possible to 500 ms before the new second starts.
+	 */
+	if ( time_state == TIME_BAD ||
+	     xtime.tv_sec > last_rtc_update + 660 )
+	/*if (time_state != TIME_BAD && xtime.tv_sec > last_rtc_update + 660 &&
+	    xtime.tv_usec > 500000 - (tick >> 1) &&
+	    xtime.tv_usec < 500000 + (tick >> 1))*/
+		if (set_rtc_mmss(xtime.tv_sec) == 0)
+			last_rtc_update = xtime.tv_sec;
+		else
+			last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
+
+
+#ifdef CONFIG_HEARTBEAT
+	/* use hard disk LED as a heartbeat instead -- much more useful
+	   for debugging -- Cort */
+	switch(kstat.interrupts[0] % 101)
+	{
+	/* act like an actual heart beat -- ie thump-thump-pause... */
+	case 0:
+	case 20:
+		outb(1,IBM_HDD_LED);
+		break;
+	case 7:
+	case 27:
+		outb(0,IBM_HDD_LED);
+		break;
+	case 100:
+		break;
+	}
+#endif
+}
+
+
+/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
+ * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
+ * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
+ *
+ * [For the Julian calendar (which was used in Russia before 1917,
+ * Britain & colonies before 1752, anywhere else before 1582,
+ * and is still in use by some communities) leave out the
+ * -year/100+year/400 terms, and add 10.]
+ *
+ * This algorithm was first published by Gauss (I think).
+ *
+ * WARNING: this function will overflow on 2106-02-07 06:28:16 on
+ * machines were long is 32-bit! (However, as time_t is signed, we
+ * will already get problems at other places on 2038-01-19 03:14:08)
+ */
+static inline unsigned long mktime(unsigned int year, unsigned int mon,
+				   unsigned int day, unsigned int hour,
+				   unsigned int min, unsigned int sec)
+{
+	if (0 >= (int) (mon -= 2)) {	/* 1..12 -> 11,12,1..10 */
+		mon += 12;	/* Puts Feb last since it has leap day */
+		year -= 1;
+	}
+	return (((
+		(unsigned long)(year/4 - year/100 + year/400 + 367*mon/12 + day) +
+		year*365 - 719499
+		)*24 + hour /* now have hours */
+		)*60 + min /* now have minutes */
+		)*60 + sec; /* finally seconds */
+}
+
+void time_init(void)
+{
+	void (*irq_handler)(int, void *,struct pt_regs *);
+	xtime.tv_sec = get_cmos_time();
+	xtime.tv_usec = 0;
+
+	/* If we have the CPU hardware time counters, use them */
+	irq_handler = timer_interrupt;
+	if (request_irq(TIMER_IRQ, irq_handler, 0, "timer", NULL) != 0)
+		panic("Could not allocate timer IRQ!");
+}