patch-2.1.51 linux/arch/ppc/kernel/time.c

• Lines: 222
• Date: Sat Aug 16 09:51:08 1997
• Orig file: v2.1.50/linux/arch/ppc/kernel/time.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.50/linux/arch/ppc/kernel/time.c linux/arch/ppc/kernel/time.c
@@ -0,0 +1,221 @@
+/*
+ * $Id: time.c,v 1.8 1997/08/11 08:37:51 cort Exp $
+ * Common time routines among all ppc machines.
+ *
+ * Written by Cort Dougan (cort@cs.nmt.edu) to merge
+ * Paul Mackerras' version and mine for PReP and Pmac.
+ */
+
+#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 <linux/time.h>
+
+#include <asm/segment.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+#include <asm/nvram.h>
+
+#include "time.h"
+
+/* this is set to the appropriate pmac/prep func in init_IRQ() */
+int (*set_rtc_time)(unsigned long);
+
+/* keep track of when we need to update the rtc */
+unsigned long last_rtc_update = 0;
+
+/* The decrementer counts down by 128 every 128ns on a 601. */
+#define DECREMENTER_COUNT_601	(1000000000 / HZ)
+#define COUNT_PERIOD_NUM_601	1
+#define COUNT_PERIOD_DEN_601	1000
+
+unsigned decrementer_count;	/* count value for 1e6/HZ microseconds */
+unsigned count_period_num;	/* 1 decrementer count equals */
+unsigned count_period_den;	/* count_period_num / count_period_den us */
+
+/* Accessor functions for the decrementer register. */
+inline unsigned long
+get_dec(void)
+{
+	int ret;
+
+	asm volatile("mfspr %0,22" : "=r" (ret) :);
+	return ret;
+}
+
+inline void
+set_dec(int val)
+{
+	asm volatile("mtspr 22,%0" : : "r" (val));
+}
+
+/*
+ * timer_interrupt - gets called when the decrementer overflows,
+ * with interrupts disabled.
+ * We set it up to overflow again in 1/HZ seconds.
+ */
+void timer_interrupt(struct pt_regs * regs)
+{
+	int dval, d;
+	while ((dval = get_dec()) < 0) {
+		/*
+		 * Wait for the decrementer to change, then jump
+		 * in and add decrementer_count to its value
+		 * (quickly, before it changes again!)
+		 */
+		while ((d = get_dec()) == dval)
+			;
+		set_dec(d + decrementer_count);
+		do_timer(regs);
+		/*
+		 * update the rtc when needed
+		 */
+		if ( xtime.tv_sec > last_rtc_update + 660 )
+			if (set_rtc_time(xtime.tv_sec) == 0)
+				last_rtc_update = xtime.tv_sec;
+			else
+				last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
+	}
+}
+
+/*
+ * This version of gettimeofday has microsecond resolution.
+ */
+void do_gettimeofday(struct timeval *tv)
+{
+	unsigned long flags;
+
+	save_flags(flags);
+	cli();
+	*tv = xtime;
+	tv->tv_usec += (decrementer_count - get_dec())
+	    * count_period_num / count_period_den;
+	if (tv->tv_usec >= 1000000) {
+		tv->tv_usec -= 1000000;
+		tv->tv_sec++;
+	}
+	restore_flags(flags);
+}
+
+void do_settimeofday(struct timeval *tv)
+{
+	unsigned long flags;
+	int frac_tick;
+	
+	last_rtc_update = 0; /* so the rtc gets updated soon */
+	
+	frac_tick = tv->tv_usec % (1000000 / HZ);
+	save_flags(flags);
+	cli();
+	xtime.tv_sec = tv->tv_sec;
+	xtime.tv_usec = tv->tv_usec - frac_tick;
+	set_dec(frac_tick * count_period_den / count_period_num);
+	restore_flags(flags);
+}
+
+
+void
+time_init(void)
+{
+#ifdef CONFIG_PREP
+	/* pmac hasn't yet called via_cuda_init() */
+	if ( _machine != _MACH_Pmac ) /* prep */
+	{
+		xtime.tv_sec = prep_get_rtc_time();
+		xtime.tv_usec = 0;
+		/*
+		 * mark the rtc/on-chip timer as in sync
+		 * so we don't update right away
+		 */
+		last_rtc_update = xtime.tv_sec;
+	}
+#endif /* CONFIG_PREP */
+	if ((_get_PVR() >> 16) == 1) {
+		/* 601 processor: dec counts down by 128 every 128ns */
+		decrementer_count = DECREMENTER_COUNT_601;
+		count_period_num = COUNT_PERIOD_NUM_601;
+		count_period_den = COUNT_PERIOD_DEN_601;
+	} else {
+		/*
+		 * These should setup decrementer_count 
+		 */
+		if ( _machine == _MACH_Pmac )
+			pmac_calibrate_decr();
+#ifdef CONFIG_PREP
+		else /* PReP */
+			prep_calibrate_decr();
+#endif /* CONFIG_PREP */
+	}
+
+	if ( _machine == _MACH_Pmac )
+		set_rtc_time = pmac_set_rtc_time;
+#ifdef CONFIG_PREP
+	else /* prep */
+		set_rtc_time = prep_set_rtc_time;
+#endif /* CONFIG_PREP */
+		
+	set_dec(decrementer_count);
+}
+
+#ifdef CONFIG_PREP
+/*
+ * Uses the on-board timer to calibrate the on-chip decrementer register
+ * for prep systems.  On the pmac the OF tells us what the frequency is
+ * but on prep we have to figure it out.
+ * -- Cort
+ */
+int calibrate_done = 0;
+volatile int *done_ptr = &calibrate_done;
+void prep_calibrate_decr(void)
+{
+	unsigned long flags;
+	
+	save_flags(flags);
+	
+#define TIMER0_COUNT 0x40
+#define TIMER_CONTROL 0x43
+	/* set timer to periodic mode */
+	outb_p(0x34,TIMER_CONTROL);/* binary, mode 2, LSB/MSB, ch 0 */
+	/* set the clock to ~100 Hz */
+	outb_p(LATCH & 0xff , TIMER0_COUNT);	/* LSB */
+	outb(LATCH >> 8 , TIMER0_COUNT);	/* MSB */
+	
+	if (request_irq(0, prep_calibrate_decr_handler, 0, "timer", NULL) != 0)
+		panic("Could not allocate timer IRQ!");
+	__sti();
+	while ( ! *done_ptr ) /* nothing */; /* wait for calibrate */
+        restore_flags(flags);
+	free_irq( 0, NULL);
+}
+
+void prep_calibrate_decr_handler(int irq, void *dev, struct pt_regs * regs)
+{
+	int freq, divisor;
+	static unsigned long t1 = 0, t2 = 0;
+
+	if ( !t1 )
+		t1 = get_dec();
+	else if (!t2)
+	{
+		t2 = get_dec();
+		t2 = t1-t2;  /* decr's in 1/HZ */
+		t2 = t2*HZ;  /* # decrs in 1s - thus in Hz */
+		freq = t2 * 60;	/* try to make freq/1e6 an integer */
+		divisor = 60;
+		printk("time_init: decrementer frequency = %d/%d (%luMHz)\n",
+		       freq, divisor,t2>>20);
+		decrementer_count = freq / HZ / divisor;
+		count_period_num = divisor;
+		count_period_den = freq / 1000000;
+		*done_ptr = 1;
+	}
+}
+#endif /* CONFIG_PREP */