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