fs/proc/uptime.c

   1 #include <linux/fs.h>
   2 #include <linux/init.h>
   3 #include <linux/proc_fs.h>
   4 #include <linux/sched.h>
   5 #include <linux/seq_file.h>
   6 #include <linux/time.h>
   7 #include <linux/kernel_stat.h>
   8
   9 static int uptime_proc_show(struct seq_file *m, void *v)
  10 {
  11         struct timespec uptime;
  12         struct timespec idle;
  13         u64 nsec;
  14         u32 rem;
  15         int i;
  16
  17         nsec = 0;
  18         for_each_possible_cpu(i)
  19                 nsec += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
  20
  21         get_monotonic_boottime(&uptime);
  22         idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
  23         idle.tv_nsec = rem;
  24         seq_printf(m, "%lu.%02lu %lu.%02lu\n",
  25                         (unsigned long) uptime.tv_sec,
  26                         (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
  27                         (unsigned long) idle.tv_sec,
  28                         (idle.tv_nsec / (NSEC_PER_SEC / 100)));
  29         return 0;
  30 }
  31
  32 static int uptime_proc_open(struct inode *inode, struct file *file)
  33 {
  34         return single_open(file, uptime_proc_show, NULL);
  35 }
  36
  37 static const struct file_operations uptime_proc_fops = {
  38         .open           = uptime_proc_open,
  39         .read           = seq_read,
  40         .llseek         = seq_lseek,
  41         .release        = single_release,
  42 };
  43
  44 static int __init proc_uptime_init(void)
  45 {
  46         proc_create("uptime", 0, NULL, &uptime_proc_fops);
  47         return 0;
  48 }
  49 fs_initcall(proc_uptime_init);