arch/xtensa/kernel/time.c

   1 /*
   2  * arch/xtensa/kernel/time.c
   3  *
   4  * Timer and clock support.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  *
  10  * Copyright (C) 2005 Tensilica Inc.
  11  *
  12  * Chris Zankel <chris@zankel.net>
  13  */
  14
  15 #include <linux/errno.h>
  16 #include <linux/time.h>
  17 #include <linux/timex.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/irq.h>
  22 #include <linux/profile.h>
  23 #include <linux/delay.h>
  24
  25 #include <asm/timex.h>
  26 #include <asm/platform.h>
  27
  28
  29 extern volatile unsigned long wall_jiffies;
  30
  31 DEFINE_SPINLOCK(rtc_lock);
  32 EXPORT_SYMBOL(rtc_lock);
  33
  34
  35 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
  36 unsigned long ccount_per_jiffy;         /* per 1/HZ */
  37 unsigned long ccount_nsec;              /* nsec per ccount increment */
  38 #endif
  39
  40 unsigned int last_ccount_stamp;
  41 static long last_rtc_update = 0;
  42
  43 /*
  44  * Scheduler clock - returns current tim in nanosec units.
  45  */
  46
  47 unsigned long long sched_clock(void)
  48 {
  49         return (unsigned long long)jiffies * (1000000000 / HZ);
  50 }
  51
  52 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs);
  53 static struct irqaction timer_irqaction = {
  54         .handler =      timer_interrupt,
  55         .flags =        IRQF_DISABLED,
  56         .name =         "timer",
  57 };
  58
  59 void __init time_init(void)
  60 {
  61         time_t sec_o, sec_n = 0;
  62
  63         /* The platform must provide a function to calibrate the processor
  64          * speed for the CALIBRATE.
  65          */
  66
  67 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
  68         printk("Calibrating CPU frequency ");
  69         platform_calibrate_ccount();
  70         printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
  71                         (int)(ccount_per_jiffy/(10000/HZ))%100);
  72 #endif
  73
  74         /* Set time from RTC (if provided) */
  75
  76         if (platform_get_rtc_time(&sec_o) == 0)
  77                 while (platform_get_rtc_time(&sec_n))
  78                         if (sec_o != sec_n)
  79                                 break;
  80
  81         xtime.tv_nsec = 0;
  82         last_rtc_update = xtime.tv_sec = sec_n;
  83         last_ccount_stamp = get_ccount();
  84
  85         set_normalized_timespec(&wall_to_monotonic,
  86                 -xtime.tv_sec, -xtime.tv_nsec);
  87
  88         /* Initialize the linux timer interrupt. */
  89
  90         setup_irq(LINUX_TIMER_INT, &timer_irqaction);
  91         set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
  92 }
  93
  94
  95 int do_settimeofday(struct timespec *tv)
  96 {
  97         time_t wtm_sec, sec = tv->tv_sec;
  98         long wtm_nsec, nsec = tv->tv_nsec;
  99         unsigned long ccount;
 100
 101         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 102                 return -EINVAL;
 103
 104         write_seqlock_irq(&xtime_lock);
 105
 106         /* This is revolting. We need to set "xtime" correctly. However, the
 107          * value in this location is the value at the most recent update of
 108          * wall time.  Discover what correction gettimeofday() would have
 109          * made, and then undo it!
 110          */
 111         ccount = get_ccount();
 112         nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
 113         nsec -= (jiffies - wall_jiffies) * CCOUNT_PER_JIFFY * CCOUNT_NSEC;
 114
 115         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 116         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 117
 118         set_normalized_timespec(&xtime, sec, nsec);
 119         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 120
 121         ntp_clear();
 122         write_sequnlock_irq(&xtime_lock);
 123         return 0;
 124 }
 125
 126 EXPORT_SYMBOL(do_settimeofday);
 127
 128
 129 void do_gettimeofday(struct timeval *tv)
 130 {
 131         unsigned long flags;
 132         unsigned long sec, usec, delta, lost, seq;
 133
 134         do {
 135                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 136
 137                 delta = get_ccount() - last_ccount_stamp;
 138                 sec = xtime.tv_sec;
 139                 usec = (xtime.tv_nsec / NSEC_PER_USEC);
 140
 141                 lost = jiffies - wall_jiffies;
 142
 143         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 144
 145         usec += lost * (1000000UL/HZ) + (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
 146         for (; usec >= 1000000; sec++, usec -= 1000000)
 147                 ;
 148
 149         tv->tv_sec = sec;
 150         tv->tv_usec = usec;
 151 }
 152
 153 EXPORT_SYMBOL(do_gettimeofday);
 154
 155 /*
 156  * The timer interrupt is called HZ times per second.
 157  */
 158
 159 irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
 160 {
 161
 162         unsigned long next;
 163
 164         next = get_linux_timer();
 165
 166 again:
 167         while ((signed long)(get_ccount() - next) > 0) {
 168
 169                 profile_tick(CPU_PROFILING, regs);
 170 #ifndef CONFIG_SMP
 171                 update_process_times(user_mode(regs));
 172 #endif
 173
 174                 write_seqlock(&xtime_lock);
 175
 176                 last_ccount_stamp = next;
 177                 next += CCOUNT_PER_JIFFY;
 178                 do_timer (regs); /* Linux handler in kernel/timer.c */
 179
 180                 if (ntp_synced() &&
 181                     xtime.tv_sec - last_rtc_update >= 659 &&
 182                     abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ &&
 183                     jiffies - wall_jiffies == 1) {
 184
 185                         if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
 186                                 last_rtc_update = xtime.tv_sec+1;
 187                         else
 188                                 /* Do it again in 60 s */
 189                                 last_rtc_update += 60;
 190                 }
 191                 write_sequnlock(&xtime_lock);
 192         }
 193
 194         /* NOTE: writing CCOMPAREn clears the interrupt.  */
 195
 196         set_linux_timer (next);
 197
 198         /* Make sure we didn't miss any tick... */
 199
 200         if ((signed long)(get_ccount() - next) > 0)
 201                 goto again;
 202
 203         /* Allow platform to do something useful (Wdog). */
 204
 205         platform_heartbeat();
 206
 207         return IRQ_HANDLED;
 208 }
 209
 210 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
 211 void __devinit calibrate_delay(void)
 212 {
 213         loops_per_jiffy = CCOUNT_PER_JIFFY;
 214         printk("Calibrating delay loop (skipped)... "
 215                "%lu.%02lu BogoMIPS preset\n",
 216                loops_per_jiffy/(1000000/HZ),
 217                (loops_per_jiffy/(10000/HZ)) % 100);
 218 }
 219 #endif
 220