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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/parisc/kernel/time.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/parisc/kernel/time.c')
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diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c
new file mode 100644
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+/*
+ * linux/arch/parisc/kernel/time.c
+ *
+ * Copyright (C) 1991, 1992, 1995 Linus Torvalds
+ * Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
+ * Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org)
+ *
+ * 1994-07-02 Alan Modra
+ * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
+ * 1998-12-20 Updated NTP code according to technical memorandum Jan '96
+ * "A Kernel Model for Precision Timekeeping" by Dave Mills
+ */
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/module.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/init.h>
+#include <linux/smp.h>
+#include <linux/profile.h>
+
+#include <asm/uaccess.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/param.h>
+#include <asm/pdc.h>
+#include <asm/led.h>
+
+#include <linux/timex.h>
+
+u64 jiffies_64 = INITIAL_JIFFIES;
+
+EXPORT_SYMBOL(jiffies_64);
+
+/* xtime and wall_jiffies keep wall-clock time */
+extern unsigned long wall_jiffies;
+
+static long clocktick; /* timer cycles per tick */
+static long halftick;
+
+#ifdef CONFIG_SMP
+extern void smp_do_timer(struct pt_regs *regs);
+#endif
+
+irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ long now;
+ long next_tick;
+ int nticks;
+ int cpu = smp_processor_id();
+
+ profile_tick(CPU_PROFILING, regs);
+
+ now = mfctl(16);
+ /* initialize next_tick to time at last clocktick */
+ next_tick = cpu_data[cpu].it_value;
+
+ /* since time passes between the interrupt and the mfctl()
+ * above, it is never true that last_tick + clocktick == now. If we
+ * never miss a clocktick, we could set next_tick = last_tick + clocktick
+ * but maybe we'll miss ticks, hence the loop.
+ *
+ * Variables are *signed*.
+ */
+
+ nticks = 0;
+ while((next_tick - now) < halftick) {
+ next_tick += clocktick;
+ nticks++;
+ }
+ mtctl(next_tick, 16);
+ cpu_data[cpu].it_value = next_tick;
+
+ while (nticks--) {
+#ifdef CONFIG_SMP
+ smp_do_timer(regs);
+#else
+ update_process_times(user_mode(regs));
+#endif
+ if (cpu == 0) {
+ write_seqlock(&xtime_lock);
+ do_timer(regs);
+ write_sequnlock(&xtime_lock);
+ }
+ }
+
+#ifdef CONFIG_CHASSIS_LCD_LED
+ /* Only schedule the led tasklet on cpu 0, and only if it
+ * is enabled.
+ */
+ if (cpu == 0 && !atomic_read(&led_tasklet.count))
+ tasklet_schedule(&led_tasklet);
+#endif
+
+ /* check soft power switch status */
+ if (cpu == 0 && !atomic_read(&power_tasklet.count))
+ tasklet_schedule(&power_tasklet);
+
+ return IRQ_HANDLED;
+}
+
+/*** converted from ia64 ***/
+/*
+ * Return the number of micro-seconds that elapsed since the last
+ * update to wall time (aka xtime aka wall_jiffies). The xtime_lock
+ * must be at least read-locked when calling this routine.
+ */
+static inline unsigned long
+gettimeoffset (void)
+{
+#ifndef CONFIG_SMP
+ /*
+ * FIXME: This won't work on smp because jiffies are updated by cpu 0.
+ * Once parisc-linux learns the cr16 difference between processors,
+ * this could be made to work.
+ */
+ long last_tick;
+ long elapsed_cycles;
+
+ /* it_value is the intended time of the next tick */
+ last_tick = cpu_data[smp_processor_id()].it_value;
+
+ /* Subtract one tick and account for possible difference between
+ * when we expected the tick and when it actually arrived.
+ * (aka wall vs real)
+ */
+ last_tick -= clocktick * (jiffies - wall_jiffies + 1);
+ elapsed_cycles = mfctl(16) - last_tick;
+
+ /* the precision of this math could be improved */
+ return elapsed_cycles / (PAGE0->mem_10msec / 10000);
+#else
+ return 0;
+#endif
+}
+
+void
+do_gettimeofday (struct timeval *tv)
+{
+ unsigned long flags, seq, usec, sec;
+
+ do {
+ seq = read_seqbegin_irqsave(&xtime_lock, flags);
+ usec = gettimeoffset();
+ sec = xtime.tv_sec;
+ usec += (xtime.tv_nsec / 1000);
+ } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
+
+ while (usec >= 1000000) {
+ usec -= 1000000;
+ ++sec;
+ }
+
+ tv->tv_sec = sec;
+ tv->tv_usec = usec;
+}
+
+EXPORT_SYMBOL(do_gettimeofday);
+
+int
+do_settimeofday (struct timespec *tv)
+{
+ time_t wtm_sec, sec = tv->tv_sec;
+ long wtm_nsec, nsec = tv->tv_nsec;
+
+ if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
+ return -EINVAL;
+
+ write_seqlock_irq(&xtime_lock);
+ {
+ /*
+ * This is revolting. We need to set "xtime"
+ * correctly. However, the value in this location is
+ * the value at the most recent update of wall time.
+ * Discover what correction gettimeofday would have
+ * done, and then undo it!
+ */
+ nsec -= gettimeoffset() * 1000;
+
+ wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
+ wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
+
+ set_normalized_timespec(&xtime, sec, nsec);
+ set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
+
+ time_adjust = 0; /* stop active adjtime() */
+ time_status |= STA_UNSYNC;
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_esterror = NTP_PHASE_LIMIT;
+ }
+ write_sequnlock_irq(&xtime_lock);
+ clock_was_set();
+ return 0;
+}
+EXPORT_SYMBOL(do_settimeofday);
+
+/*
+ * XXX: We can do better than this.
+ * Returns nanoseconds
+ */
+
+unsigned long long sched_clock(void)
+{
+ return (unsigned long long)jiffies * (1000000000 / HZ);
+}
+
+
+void __init time_init(void)
+{
+ unsigned long next_tick;
+ static struct pdc_tod tod_data;
+
+ clocktick = (100 * PAGE0->mem_10msec) / HZ;
+ halftick = clocktick / 2;
+
+ /* Setup clock interrupt timing */
+
+ next_tick = mfctl(16);
+ next_tick += clocktick;
+ cpu_data[smp_processor_id()].it_value = next_tick;
+
+ /* kick off Itimer (CR16) */
+ mtctl(next_tick, 16);
+
+ if(pdc_tod_read(&tod_data) == 0) {
+ write_seqlock_irq(&xtime_lock);
+ xtime.tv_sec = tod_data.tod_sec;
+ xtime.tv_nsec = tod_data.tod_usec * 1000;
+ set_normalized_timespec(&wall_to_monotonic,
+ -xtime.tv_sec, -xtime.tv_nsec);
+ write_sequnlock_irq(&xtime_lock);
+ } else {
+ printk(KERN_ERR "Error reading tod clock\n");
+ xtime.tv_sec = 0;
+ xtime.tv_nsec = 0;
+ }
+}
+