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