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