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/config.h>
  16 #include <linux/errno.h>
  17 #include <linux/time.h>
  18 #include <linux/timex.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/module.h>
  21 #include <linux/init.h>
  22 #include <linux/irq.h>
  23 #include <linux/profile.h>
  24 #include <linux/delay.h>
  25
  26 #include <asm/timex.h>
  27 #include <asm/platform.h>
  28
  29
  30 extern volatile unsigned long wall_jiffies;
  31
  32 u64 jiffies_64 = INITIAL_JIFFIES;
  33 EXPORT_SYMBOL(jiffies_64);
  34
  35 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
  36 EXPORT_SYMBOL(rtc_lock);
  37
  38
  39 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
  40 unsigned long ccount_per_jiffy;         /* per 1/HZ */
  41 unsigned long ccount_nsec;              /* nsec per ccount increment */
  42 #endif
  43
  44 unsigned int last_ccount_stamp;
  45 static long last_rtc_update = 0;
  46
  47 /*
  48  * Scheduler clock - returns current tim in nanosec units.
  49  */
  50
  51 unsigned long long sched_clock(void)
  52 {
  53         return (unsigned long long)jiffies * (1000000000 / HZ);
  54 }
  55
  56 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs);
  57 static struct irqaction timer_irqaction = {
  58         .handler =      timer_interrupt,
  59         .flags =        SA_INTERRUPT,
  60         .name =         "timer",
  61 };
  62
  63 void __init time_init(void)
  64 {
  65         time_t sec_o, sec_n = 0;
  66
  67         /* The platform must provide a function to calibrate the processor
  68          * speed for the CALIBRATE.
  69          */
  70
  71 #if CONFIG_XTENSA_CALIBRATE_CCOUNT
  72         printk("Calibrating CPU frequency ");
  73         platform_calibrate_ccount();
  74         printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
  75                         (int)(ccount_per_jiffy/(10000/HZ))%100);
  76 #endif
  77
  78         /* Set time from RTC (if provided) */
  79
  80         if (platform_get_rtc_time(&sec_o) == 0)
  81                 while (platform_get_rtc_time(&sec_n))
  82                         if (sec_o != sec_n)
  83                                 break;
  84
  85         xtime.tv_nsec = 0;
  86         last_rtc_update = xtime.tv_sec = sec_n;
  87         last_ccount_stamp = get_ccount();
  88
  89         set_normalized_timespec(&wall_to_monotonic,
  90                 -xtime.tv_sec, -xtime.tv_nsec);
  91
  92         /* Initialize the linux timer interrupt. */
  93
  94         setup_irq(LINUX_TIMER_INT, &timer_irqaction);
  95         set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
  96 }
  97
  98
  99 int do_settimeofday(struct timespec *tv)
 100 {
 101         time_t wtm_sec, sec = tv->tv_sec;
 102         long wtm_nsec, nsec = tv->tv_nsec;
 103         unsigned long ccount;
 104
 105         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 106                 return -EINVAL;
 107
 108         write_seqlock_irq(&xtime_lock);
 109
 110         /* This is revolting. We need to set "xtime" correctly. However, the
 111          * value in this location is the value at the most recent update of
 112          * wall time.  Discover what correction gettimeofday() would have
 113          * made, and then undo it!
 114          */
 115         ccount = get_ccount();
 116         nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
 117         nsec -= (jiffies - wall_jiffies) * CCOUNT_PER_JIFFY * CCOUNT_NSEC;
 118
 119         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 120         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 121
 122         set_normalized_timespec(&xtime, sec, nsec);
 123         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 124
 125         time_adjust = 0;                /* stop active adjtime() */
 126         time_status |= STA_UNSYNC;
 127         time_maxerror = NTP_PHASE_LIMIT;
 128         time_esterror = NTP_PHASE_LIMIT;
 129         write_sequnlock_irq(&xtime_lock);
 130         return 0;
 131 }
 132
 133 EXPORT_SYMBOL(do_settimeofday);
 134
 135
 136 void do_gettimeofday(struct timeval *tv)
 137 {
 138         unsigned long flags;
 139         unsigned long sec, usec, delta, lost, seq;
 140
 141         do {
 142                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 143
 144                 delta = get_ccount() - last_ccount_stamp;
 145                 sec = xtime.tv_sec;
 146                 usec = (xtime.tv_nsec / NSEC_PER_USEC);
 147
 148                 lost = jiffies - wall_jiffies;
 149
 150         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 151
 152         usec += lost * (1000000UL/HZ) + (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
 153         for (; usec >= 1000000; sec++, usec -= 1000000)
 154                 ;
 155
 156         tv->tv_sec = sec;
 157         tv->tv_usec = usec;
 158 }
 159
 160 EXPORT_SYMBOL(do_gettimeofday);
 161
 162 /*
 163  * The timer interrupt is called HZ times per second.
 164  */
 165
 166 irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
 167 {
 168
 169         unsigned long next;
 170
 171         next = get_linux_timer();
 172
 173 again:
 174         while ((signed long)(get_ccount() - next) > 0) {
 175
 176                 profile_tick(CPU_PROFILING, regs);
 177 #ifndef CONFIG_SMP
 178                 update_process_times(user_mode(regs));
 179 #endif
 180
 181                 write_seqlock(&xtime_lock);
 182
 183                 last_ccount_stamp = next;
 184                 next += CCOUNT_PER_JIFFY;
 185                 do_timer (regs); /* Linux handler in kernel/timer.c */
 186
 187                 if ((time_status & STA_UNSYNC) == 0 &&
 188                     xtime.tv_sec - last_rtc_update >= 659 &&
 189                     abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ &&
 190                     jiffies - wall_jiffies == 1) {
 191
 192                         if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
 193                                 last_rtc_update = xtime.tv_sec+1;
 194                         else
 195                                 /* Do it again in 60 s */
 196                                 last_rtc_update += 60;
 197                 }
 198                 write_sequnlock(&xtime_lock);
 199         }
 200
 201         /* NOTE: writing CCOMPAREn clears the interrupt.  */
 202
 203         set_linux_timer (next);
 204
 205         /* Make sure we didn't miss any tick... */
 206
 207         if ((signed long)(get_ccount() - next) > 0)
 208                 goto again;
 209
 210         /* Allow platform to do something usefull (Wdog). */
 211
 212         platform_heartbeat();
 213
 214         return IRQ_HANDLED;
 215 }
 216
 217 #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
 218 void __devinit calibrate_delay(void)
 219 {
 220         loops_per_jiffy = CCOUNT_PER_JIFFY;
 221         printk("Calibrating delay loop (skipped)... "
 222                "%lu.%02lu BogoMIPS preset\n",
 223                loops_per_jiffy/(1000000/HZ),
 224                (loops_per_jiffy/(10000/HZ)) % 100);
 225 }
 226 #endif
 227