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