patch-2.4.19 linux-2.4.19/arch/mips/galileo-boards/ev96100/time.c

• Lines: 270
• Date: Fri Aug 2 17:39:43 2002
• Orig file: linux-2.4.18/arch/mips/galileo-boards/ev96100/time.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.18/arch/mips/galileo-boards/ev96100/time.c linux-2.4.19/arch/mips/galileo-boards/ev96100/time.c
@@ -0,0 +1,269 @@
+/*
+ *
+ * BRIEF MODULE DESCRIPTION
+ *	Galileo EV96100 rtc routines.
+ *
+ * Copyright 2000 MontaVista Software Inc.
+ * Author: MontaVista Software, Inc.
+ *         	ppopov@mvista.com or source@mvista.com
+ *
+ * This file was derived from Carsten Langgaard's 
+ * arch/mips/mips-boards/atlas/atlas_rtc.c.
+ *
+ * Carsten Langgaard, carstenl@mips.com
+ * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ *
+ *  THIS  SOFTWARE  IS PROVIDED   ``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 AUTHOR  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.
+ *
+ *  You should have received a copy of the  GNU General Public License along
+ *  with this program; if not, write  to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/timex.h>
+
+#include <asm/mipsregs.h>
+#include <asm/ptrace.h>
+
+
+#define ALLINTS (IE_IRQ0 | IE_IRQ1 | IE_IRQ2 | IE_IRQ3 | IE_IRQ4 | IE_IRQ5)
+
+extern volatile unsigned long wall_jiffies;
+unsigned long missed_heart_beats = 0;
+
+static unsigned long r4k_offset; /* Amount to increment compare reg each time */
+static unsigned long r4k_cur;    /* What counter should be at next timer irq */
+extern rwlock_t xtime_lock;
+
+static inline void ack_r4ktimer(unsigned long newval)
+{
+	write_32bit_cp0_register(CP0_COMPARE, newval);
+}
+
+static int set_rtc_mmss(unsigned long nowtime)
+{
+    /* EV96100 does not have a real time clock */
+    int retval = 0;
+
+    return retval;
+}
+
+
+
+/* 
+ * Figure out the r4k offset, the amount to increment the compare
+ * register for each time tick. 
+ * Use the RTC to calculate offset.
+ */
+static unsigned long __init cal_r4koff(void)
+{
+	unsigned long count;
+        count = 300000000/2;
+	return (count / HZ);
+}
+
+
+static unsigned long __init get_mips_time(void)
+{
+	unsigned int year, mon, day, hour, min, sec;
+
+        year = 2000;
+        mon = 10;
+        day = 31;
+        hour = 0;
+        min = 0;
+        sec = 0;
+	return mktime(year, mon, day, hour, min, sec);
+}
+
+
+/*
+ * called from start_kernel()
+ */
+void __init time_init(void)
+{
+
+        unsigned int est_freq;
+
+	r4k_offset = cal_r4koff();
+
+	est_freq = 2*r4k_offset*HZ;	
+	est_freq += 5000;    /* round */
+	est_freq -= est_freq%10000;
+	printk("CPU frequency %d.%02d MHz\n", est_freq/1000000, 
+	       (est_freq%1000000)*100/1000000);
+	r4k_cur = (read_32bit_cp0_register(CP0_COUNT) + r4k_offset);
+
+	write_32bit_cp0_register(CP0_COMPARE, r4k_cur);
+
+        /* FIX ME */
+	change_cp0_status(ST0_IM, IE_IRQ5);
+}
+
+/* This is for machines which generate the exact clock. */
+#define USECS_PER_JIFFY (1000000/HZ)
+
+/* Cycle counter value at the previous timer interrupt.. */
+
+static unsigned int timerhi = 0, timerlo = 0;
+
+/*
+ * FIXME: Does playing with the RP bit in c0_status interfere with this code?
+ */
+static unsigned long do_fast_gettimeoffset(void)
+{
+	u32 count;
+	unsigned long res, tmp;
+
+	/* Last jiffy when do_fast_gettimeoffset() was called. */
+	static unsigned long last_jiffies=0;
+	unsigned long quotient;
+
+	/*
+	 * Cached "1/(clocks per usec)*2^32" value.
+	 * It has to be recalculated once each jiffy.
+	 */
+	static unsigned long cached_quotient=0;
+
+	tmp = jiffies;
+
+	quotient = cached_quotient;
+
+	if (tmp && last_jiffies != tmp) {
+		last_jiffies = tmp;
+		__asm__(".set\tnoreorder\n\t"
+			".set\tnoat\n\t"
+			".set\tmips3\n\t"
+			"lwu\t%0,%2\n\t"
+			"dsll32\t$1,%1,0\n\t"
+			"or\t$1,$1,%0\n\t"
+			"ddivu\t$0,$1,%3\n\t"
+			"mflo\t$1\n\t"
+			"dsll32\t%0,%4,0\n\t"
+			"nop\n\t"
+			"ddivu\t$0,%0,$1\n\t"
+			"mflo\t%0\n\t"
+			".set\tmips0\n\t"
+			".set\tat\n\t"
+			".set\treorder"
+			:"=&r" (quotient)
+			:"r" (timerhi),
+			 "m" (timerlo),
+			 "r" (tmp),
+			 "r" (USECS_PER_JIFFY));
+		cached_quotient = quotient;
+	}
+
+	/* Get last timer tick in absolute kernel time */
+	count = read_32bit_cp0_register(CP0_COUNT);
+
+	/* .. relative to previous jiffy (32 bits is enough) */
+	count -= timerlo;
+
+	__asm__("multu\t%1,%2\n\t"
+		"mfhi\t%0"
+		:"=r" (res)
+		:"r" (count),
+		 "r" (quotient));
+
+	/*
+ 	 * Due to possible jiffies inconsistencies, we need to check 
+	 * the result so that we'll get a timer that is monotonic.
+	 */
+	if (res >= USECS_PER_JIFFY)
+		res = USECS_PER_JIFFY-1;
+
+	return res;
+}
+
+void do_gettimeofday(struct timeval *tv)
+{
+	unsigned int flags;
+
+	read_lock_irqsave (&xtime_lock, flags);
+	*tv = xtime;
+	tv->tv_usec += do_fast_gettimeoffset();
+
+	/*
+	 * xtime is atomically updated in timer_bh. jiffies - wall_jiffies
+	 * is nonzero if the timer bottom half hasnt executed yet.
+	 */
+	if (jiffies - wall_jiffies)
+		tv->tv_usec += USECS_PER_JIFFY;
+
+	read_unlock_irqrestore (&xtime_lock, flags);
+
+	if (tv->tv_usec >= 1000000) {
+		tv->tv_usec -= 1000000;
+		tv->tv_sec++;
+	}
+}
+
+void do_settimeofday(struct timeval *tv)
+{
+	write_lock_irq (&xtime_lock);
+
+	/* This is revolting. We need to set the xtime.tv_usec correctly.
+	 * However, the value in this location is is value at the last tick.
+	 * Discover what correction gettimeofday would have done, and then
+	 * undo it!
+	 */
+	tv->tv_usec -= do_fast_gettimeoffset();
+
+	if (tv->tv_usec < 0) {
+		tv->tv_usec += 1000000;
+		tv->tv_sec--;
+	}
+
+	xtime = *tv;
+	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);
+}
+
+/*
+ * There are a lot of conceptually broken versions of the MIPS timer interrupt
+ * handler floating around.  This one is rather different, but the algorithm
+ * is probably more robust.
+ */
+void mips_timer_interrupt(struct pt_regs *regs)
+{
+        int irq = 7; /* FIX ME */
+
+	if (r4k_offset == 0) {
+            goto null;
+        }
+
+	do {
+		kstat.irqs[0][irq]++;
+		do_timer(regs);
+		r4k_cur += r4k_offset;
+		ack_r4ktimer(r4k_cur);
+
+	} while (((unsigned long)read_32bit_cp0_register(CP0_COUNT) 
+                    - r4k_cur) < 0x7fffffff);
+	return;
+
+null:
+	ack_r4ktimer(0);
+}