patch-2.4.10 linux/arch/mips/au1000/common/time.c

• Lines: 287
• Date: Sun Sep 9 10:43:01 2001
• Orig file: v2.4.9/linux/arch/mips/au1000/common/time.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.9/linux/arch/mips/au1000/common/time.c linux/arch/mips/au1000/common/time.c
@@ -0,0 +1,286 @@
+/*
+ * Copyright (C) 2001 MontaVista Software, ppopov@mvista.com
+ * Copied and modified Carsten Langgaard's time.c
+ *
+ * Carsten Langgaard, carstenl@mips.com
+ * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
+ *
+ * ########################################################################
+ *
+ *  This program is free software; you can distribute it and/or modify it
+ *  under the terms of the GNU General Public License (Version 2) as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  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.,
+ *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * ########################################################################
+ *
+ * Setting up the clock on the MIPS boards.
+ */
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#include <asm/mipsregs.h>
+#include <asm/ptrace.h>
+#include <asm/div64.h>
+#include <asm/au1000.h>
+
+#include <linux/mc146818rtc.h>
+#include <linux/timex.h>
+
+extern volatile unsigned long wall_jiffies;
+unsigned long missed_heart_beats = 0;
+unsigned long uart_baud_base;
+
+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;
+
+#define ALLINTS (IE_IRQ0 | IE_IRQ1 | IE_IRQ2 | IE_IRQ3 | IE_IRQ4 | IE_IRQ5)
+
+static inline void ack_r4ktimer(unsigned long newval)
+{
+	write_32bit_cp0_register(CP0_COMPARE, newval);
+}
+
+
+/*
+ * 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 provably more robust.
+ */
+unsigned long wtimer;
+void mips_timer_interrupt(struct pt_regs *regs)
+{
+	int irq = 7;
+
+	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);
+}
+
+/* 
+ * Figure out the r4k offset, the amount to increment the compare
+ * register for each time tick. 
+ * Use the Programmable Counter 1 to do this.
+ */
+unsigned long cal_r4koff(void)
+{
+	unsigned long count;
+	unsigned long cpu_pll;
+	unsigned long cpu_speed;
+	unsigned long start, end;
+	unsigned long counter;
+	int i;
+	int trim_divide = 16;
+
+	counter = inl(PC_COUNTER_CNTRL);
+	outl(counter | PC_CNTRL_EN1, PC_COUNTER_CNTRL);
+
+	while (inl(PC_COUNTER_CNTRL) & PC_CNTRL_T1S);
+	outl(trim_divide-1, PC1_TRIM);    /* RTC now ticks at 32.768/16 kHz */
+	while (inl(PC_COUNTER_CNTRL) & PC_CNTRL_T1S);
+
+	while (inl(PC_COUNTER_CNTRL) & PC_CNTRL_C1S);
+	outl (0, PC1_COUNTER_WRITE);
+	while (inl(PC_COUNTER_CNTRL) & PC_CNTRL_C1S);
+
+	start = inl(PC1_COUNTER_READ);
+	start += 2;
+	/* wait for the beginning of a new tick */
+	while (inl(PC1_COUNTER_READ) < start);
+
+	/* Start r4k counter. */
+	write_32bit_cp0_register(CP0_COUNT, 0);
+	end = start + (32768 / trim_divide)/2; /* wait 0.5 seconds */
+
+	while (end > inl(PC1_COUNTER_READ));
+
+	count = read_32bit_cp0_register(CP0_COUNT);
+	cpu_speed = count * 2;
+	uart_baud_base = (((cpu_speed) / 4) / 16);
+	return (cpu_speed / HZ);
+}
+
+static unsigned long __init get_mips_time(void)
+{
+	return inl(PC0_COUNTER_READ);
+}
+
+void __init time_init(void)
+{
+        unsigned int est_freq, flags;
+
+	printk("calculating r4koff... ");
+	r4k_offset = cal_r4koff();
+	printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset);
+
+	//est_freq = 2*r4k_offset*HZ;	
+	est_freq = 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);
+	set_cp0_status(ALLINTS);
+
+	/* Read time from the RTC chipset. */
+	write_lock_irqsave (&xtime_lock, flags);
+	xtime.tv_sec = get_mips_time();
+	xtime.tv_usec = 0;
+	write_unlock_irqrestore(&xtime_lock, flags);
+}
+
+/* This is for machines which generate the exact clock. */
+#define USECS_PER_JIFFY (1000000/HZ)
+#define USECS_PER_JIFFY_FRAC ((1000000ULL << 32) / HZ & 0xffffffff)
+
+/* Cycle counter value at the previous timer interrupt.. */
+
+static unsigned int timerhi = 0, timerlo = 0;
+
+static unsigned long
+div64_32(unsigned long v1, unsigned long v2, unsigned long v3)
+{
+	unsigned long r0;
+	do_div64_32(r0, v1, v2, v3);
+	return r0;
+}
+
+
+/*
+ * 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;
+	unsigned long r0;
+
+	/* 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;
+		if (last_jiffies != 0) {
+			r0 = div64_32(timerhi, timerlo, tmp);
+			quotient = div64_32(USECS_PER_JIFFY, USECS_PER_JIFFY_FRAC, r0);
+			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);
+}
+
+/*
+ * The UART baud base is not known at compile time ... if
+ * we want to be able to use the same code on different
+ * speed CPUs.
+ */
+unsigned long get_au1000_uart_baud()
+{
+	return uart_baud_base;
+}