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