patch-2.3.99-pre8 linux/arch/s390/kernel/time.c

• Lines: 251
• Date: Fri May 12 11:41:45 2000
• Orig file: v2.3.99-pre7/linux/arch/s390/kernel/time.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.99-pre7/linux/arch/s390/kernel/time.c linux/arch/s390/kernel/time.c
@@ -0,0 +1,250 @@
+/*
+ *  arch/s390/kernel/time.c
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *    Author(s): Hartmut Penner (hp@de.ibm.com),
+ *               Martin Schwidefsky (schwidefsky@de.ibm.com),
+ *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
+ *
+ *  Derived from "arch/i386/kernel/time.c"
+ *    Copyright (C) 1991, 1992, 1995  Linus Torvalds
+ */
+
+#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/time.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/types.h>
+
+#include <asm/uaccess.h>
+#include <asm/delay.h>
+
+#include <linux/mc146818rtc.h>
+#include <linux/timex.h>
+
+#include <asm/irq.h>
+
+
+extern volatile unsigned long lost_ticks;
+
+/* change this if you have some constant time drift */
+#define USECS_PER_JIFFY ((signed long)1000000/HZ)
+#define CLK_TICKS_PER_JIFFY ((signed long)USECS_PER_JIFFY<<12)
+
+#define TICK_SIZE tick
+
+static uint64_t init_timer_cc, last_timer_cc;
+
+extern rwlock_t xtime_lock;
+
+void tod_to_timeval(uint64_t todval, struct timeval *xtime)
+{
+        const int high_bit = 0x80000000L;
+        const int c_f4240 = 0xf4240L;
+        const int c_7a120 = 0x7a120;
+	/* We have to divide the 64 bit value todval by 4096
+	 * (because the 2^12 bit is the one that changes every 
+         * microsecond) and then split it into seconds and
+         * microseconds. A value of max (2^52-1) divided by
+         * the value 0xF4240 can yield a max result of approx
+         * (2^32.068). Thats to big to fit into a signed int
+	 *   ... hacking time!
+         */
+	asm volatile ("L     2,%1\n\t"
+		      "LR    3,2\n\t"
+		      "SRL   2,12\n\t"
+		      "SLL   3,20\n\t"
+		      "L     4,%O1+4(%R1)\n\t"
+		      "SRL   4,12\n\t"
+		      "OR    3,4\n\t"  /* now R2/R3 contain (todval >> 12) */
+		      "SR    4,4\n\t"
+		      "CL    2,%2\n\t"
+		      "JL    .+12\n\t"
+		      "S     2,%2\n\t"
+		      "L     4,%3\n\t"
+                      "D     2,%4\n\t"
+		      "OR    3,4\n\t"
+		      "ST    2,%O0+4(%R0)\n\t"
+		      "ST    3,%0"
+		      : "=m" (*xtime) : "m" (todval),
+		        "m" (c_7a120), "m" (high_bit), "m" (c_f4240)
+		      : "cc", "memory", "2", "3", "4" );
+}
+
+unsigned long do_gettimeoffset(void) 
+{
+	__u64 timer_cc;
+
+	asm volatile ("STCK %0" : "=m" (timer_cc));
+        /* We require the offset from the previous interrupt */
+        return ((unsigned long)((timer_cc - last_timer_cc)>>12));
+}
+
+/*
+ * This version of gettimeofday has microsecond resolution.
+ */
+void do_gettimeofday(struct timeval *tv)
+{
+	extern volatile unsigned long lost_ticks;
+	unsigned long flags;
+	unsigned long usec, sec;
+
+	read_lock_irqsave(&xtime_lock, flags);
+	usec = do_gettimeoffset();
+	if (lost_ticks)
+		usec +=(USECS_PER_JIFFY*lost_ticks);
+	sec = xtime.tv_sec;
+	usec += xtime.tv_usec;
+	read_unlock_irqrestore(&xtime_lock, flags);
+
+	while (usec >= 1000000) {
+		usec -= 1000000;
+		sec++;
+	}
+
+	tv->tv_sec = sec;
+	tv->tv_usec = usec;
+}
+
+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_gettimeoffset();
+
+	while (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);
+}
+
+/*
+ * timer_interrupt() needs to keep up the real-time clock,
+ * as well as call the "do_timer()" routine every clocktick
+ */
+
+#ifdef CONFIG_SMP
+extern __u16 boot_cpu_addr;
+#endif
+
+void do_timer_interrupt(struct pt_regs *regs,int error_code)
+{
+        unsigned long flags;
+
+        /*
+         * reset timer to 10ms minus time already elapsed
+         * since timer-interrupt pending
+         */
+ 
+        save_flags(flags);
+        cli();
+#ifdef CONFIG_SMP
+	if(S390_lowcore.cpu_data.cpu_addr==boot_cpu_addr) {
+		write_lock(&xtime_lock);
+		last_timer_cc = S390_lowcore.jiffy_timer_cc;
+	}
+#else
+        last_timer_cc = S390_lowcore.jiffy_timer_cc;
+#endif
+        /* set clock comparator */
+        S390_lowcore.jiffy_timer_cc += CLK_TICKS_PER_JIFFY;
+        asm volatile ("SCKC %0" : : "m" (S390_lowcore.jiffy_timer_cc));
+
+/*
+ * In the SMP case we use the local timer interrupt to do the
+ * profiling, except when we simulate SMP mode on a uniprocessor
+ * system, in that case we have to call the local interrupt handler.
+ */
+#ifdef CONFIG_SMP
+        /* when SMP, do smp_local_timer_interrupt for *all* CPUs,
+           but only do the rest for the boot CPU */
+        smp_local_timer_interrupt(regs);
+#else
+        if (!user_mode(regs))
+                s390_do_profile(regs->psw.addr);
+#endif
+
+#ifdef CONFIG_SMP
+	if(S390_lowcore.cpu_data.cpu_addr==boot_cpu_addr)
+#endif
+	{
+		do_timer(regs);
+#ifdef CONFIG_SMP
+		write_unlock(&xtime_lock);
+#endif
+	}
+        restore_flags(flags);
+
+}
+
+/*
+ * Start the clock comparator on the current CPU
+ */
+static long cr0 __attribute__ ((aligned (8)));
+
+void init_100hz_timer(void)
+{
+        /* allow clock comparator timer interrupt */
+        asm volatile ("STCTL 0,0,%0" : "=m" (cr0) : : "memory");
+        cr0 |= 0x800;
+        asm volatile ("LCTL 0,0,%0" : : "m" (cr0) : "memory");
+        /* set clock comparator */
+        /* read the TOD clock */
+        asm volatile ("STCK %0" : "=m" (S390_lowcore.jiffy_timer_cc));
+        S390_lowcore.jiffy_timer_cc += CLK_TICKS_PER_JIFFY;
+        asm volatile ("SCKC %0" : : "m" (S390_lowcore.jiffy_timer_cc));
+}
+
+/*
+ * Initialize the TOD clock and the CPU timer of
+ * the boot cpu.
+ */
+void __init time_init(void)
+{
+	int cc;
+
+        /* kick the TOD clock */
+        asm volatile ("STCK %1\n\t"
+                      "IPM  %0\n\t"
+                      "SRL  %0,28" : "=r" (cc), "=m" (init_timer_cc));
+        switch (cc) {
+        case 0: /* clock in set state: all is fine */
+                break;
+        case 1: /* clock in non-set state: FIXME */
+                printk("time_init: TOD clock in non-set state\n");
+                break;
+        case 2: /* clock in error state: FIXME */
+                printk("time_init: TOD clock in error state\n");
+                break;
+        case 3: /* clock in stopped or not-operational state: FIXME */
+                printk("time_init: TOD clock stopped/non-operational\n");
+                break;
+        }
+        init_100hz_timer();
+        init_timer_cc = S390_lowcore.jiffy_timer_cc;
+        init_timer_cc -= 0x8126d60e46000000LL -
+                         (0x3c26700LL*1000000*4096);
+        tod_to_timeval(init_timer_cc, &xtime);
+}