arch/powerpc/sysdev/timer.c

   1 /*
   2  * Common code to keep time when machine suspends.
   3  *
   4  * Copyright 2007       Johannes Berg <johannes@sipsolutions.net>
   5  *
   6  * GPLv2
   7  */
   8
   9 #include <linux/time.h>
  10 #include <asm/rtc.h>
  11
  12 static unsigned long suspend_rtc_time;
  13
  14 /*
  15  * Reset the time after a sleep.
  16  */
  17 static int timer_resume(struct sys_device *dev)
  18 {
  19         struct timeval tv;
  20         struct timespec ts;
  21         struct rtc_time cur_rtc_tm;
  22         unsigned long cur_rtc_time, diff;
  23
  24         /* get current RTC time and convert to seconds */
  25         get_rtc_time(&cur_rtc_tm);
  26         rtc_tm_to_time(&cur_rtc_tm, &cur_rtc_time);
  27
  28         diff = cur_rtc_time - suspend_rtc_time;
  29
  30         /* adjust time of day by seconds that elapsed while
  31          * we were suspended */
  32         do_gettimeofday(&tv);
  33         ts.tv_sec = tv.tv_sec + diff;
  34         ts.tv_nsec = tv.tv_usec * NSEC_PER_USEC;
  35         do_settimeofday(&ts);
  36
  37         return 0;
  38 }
  39
  40 static int timer_suspend(struct sys_device *dev, pm_message_t state)
  41 {
  42         struct rtc_time suspend_rtc_tm;
  43         WARN_ON(!ppc_md.get_rtc_time);
  44
  45         get_rtc_time(&suspend_rtc_tm);
  46         rtc_tm_to_time(&suspend_rtc_tm, &suspend_rtc_time);
  47
  48         return 0;
  49 }
  50
  51 static struct sysdev_class timer_sysclass = {
  52         .resume = timer_resume,
  53         .suspend = timer_suspend,
  54         set_kset_name("timer"),
  55 };
  56
  57 static struct sys_device device_timer = {
  58         .id = 0,
  59         .cls = &timer_sysclass,
  60 };
  61
  62 static int time_init_device(void)
  63 {
  64         int error = sysdev_class_register(&timer_sysclass);
  65         if (!error)
  66                 error = sysdev_register(&device_timer);
  67         return error;
  68 }
  69
  70 device_initcall(time_init_device);