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
10static 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
35static int uptime_proc_open(struct inode *inode, struct file *file)
36{
37	return single_open(file, uptime_proc_show, NULL);
38}
39
40static 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
47static int __init proc_uptime_init(void)
48{
49	proc_create("uptime", 0, NULL, &uptime_proc_fops);
50	return 0;
51}
52fs_initcall(proc_uptime_init);
53