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