kernel/time/timekeeping_debug.c

   1 /*
   2  * debugfs file to track time spent in suspend
   3  *
   4  * Copyright (c) 2011, Google, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14  * more details.
  15  */
  16
  17 #include <linux/debugfs.h>
  18 #include <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/time.h>
  23
  24 #include "timekeeping_internal.h"
  25
  26 #define NUM_BINS 32
  27
  28 static unsigned int sleep_time_bin[NUM_BINS] = {0};
  29
  30 static int tk_debug_show_sleep_time(struct seq_file *s, void *data)
  31 {
  32         unsigned int bin;
  33         seq_puts(s, "      time (secs)        count\n");
  34         seq_puts(s, "------------------------------\n");
  35         for (bin = 0; bin < 32; bin++) {
  36                 if (sleep_time_bin[bin] == 0)
  37                         continue;
  38                 seq_printf(s, "%10u - %-10u %4u\n",
  39                         bin ? 1 << (bin - 1) : 0, 1 << bin,
  40                                 sleep_time_bin[bin]);
  41         }
  42         return 0;
  43 }
  44
  45 static int tk_debug_sleep_time_open(struct inode *inode, struct file *file)
  46 {
  47         return single_open(file, tk_debug_show_sleep_time, NULL);
  48 }
  49
  50 static const struct file_operations tk_debug_sleep_time_fops = {
  51         .open           = tk_debug_sleep_time_open,
  52         .read           = seq_read,
  53         .llseek         = seq_lseek,
  54         .release        = single_release,
  55 };
  56
  57 static int __init tk_debug_sleep_time_init(void)
  58 {
  59         struct dentry *d;
  60
  61         d = debugfs_create_file("sleep_time", 0444, NULL, NULL,
  62                 &tk_debug_sleep_time_fops);
  63         if (!d) {
  64                 pr_err("Failed to create sleep_time debug file\n");
  65                 return -ENOMEM;
  66         }
  67
  68         return 0;
  69 }
  70 late_initcall(tk_debug_sleep_time_init);
  71
  72 void tk_debug_account_sleep_time(struct timespec64 *t)
  73 {
  74         /* Cap bin index so we don't overflow the array */
  75         int bin = min(fls(t->tv_sec), NUM_BINS-1);
  76
  77         sleep_time_bin[bin]++;
  78         printk_deferred(KERN_INFO "Suspended for %lld.%03lu seconds\n",
  79                         (s64)t->tv_sec, t->tv_nsec / NSEC_PER_MSEC);
  80 }
  81