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 #include <linux/cputime.h>
   9
  10 static int uptime_proc_show(struct seq_file *m, void *v)
  11 {
  12         struct timespec uptime;
  13         struct timespec idle;
  14         u64 idletime;
  15         u64 nsec;
  16         u32 rem;
  17         int i;
  18
  19         idletime = 0;
  20         for_each_possible_cpu(i)
  21                 idletime += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
  22
  23         get_monotonic_boottime(&uptime);
  24         nsec = cputime64_to_jiffies64(idletime) * TICK_NSEC;
  25         idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
  26         idle.tv_nsec = rem;
  27         seq_printf(m, "%lu.%02lu %lu.%02lu\n",
  28                         (unsigned long) uptime.tv_sec,
  29                         (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
  30                         (unsigned long) idle.tv_sec,
  31                         (idle.tv_nsec / (NSEC_PER_SEC / 100)));
  32         return 0;
  33 }
  34
  35 static int uptime_proc_open(struct inode *inode, struct file *file)
  36 {
  37         return single_open(file, uptime_proc_show, NULL);
  38 }
  39
  40 static const struct file_operations uptime_proc_fops = {
  41         .open           = uptime_proc_open,
  42         .read           = seq_read,
  43         .llseek         = seq_lseek,
  44         .release        = single_release,
  45 };
  46
  47 static int __init proc_uptime_init(void)
  48 {
  49         proc_create("uptime", 0, NULL, &uptime_proc_fops);
  50         return 0;
  51 }
  52 fs_initcall(proc_uptime_init);