kernel/power/wakeup_reason.c

   1 /*
   2  * kernel/power/wakeup_reason.c
   3  *
   4  * Logs the reasons which caused the kernel to resume from
   5  * the suspend mode.
   6  *
   7  * Copyright (C) 2014 Google, Inc.
   8  * This software is licensed under the terms of the GNU General Public
   9  * License version 2, as published by the Free Software Foundation, and
  10  * may be copied, distributed, and modified under those terms.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/wakeup_reason.h>
  19 #include <linux/kernel.h>
  20 #include <linux/irq.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/io.h>
  23 #include <linux/kobject.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/init.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/notifier.h>
  28 #include <linux/suspend.h>
  29
  30
  31 #define MAX_WAKEUP_REASON_IRQS 32
  32 static int irq_list[MAX_WAKEUP_REASON_IRQS];
  33 static int irq_count;
  34 static struct kobject *wakeup_reason;
  35 static spinlock_t resume_reason_lock;
  36
  37 static ssize_t reason_show(struct kobject *kobj, struct kobj_attribute *attr,
  38                 char *buf)
  39 {
  40         int irq_no, buf_offset = 0;
  41         struct irq_desc *desc;
  42         spin_lock(&resume_reason_lock);
  43         for (irq_no = 0; irq_no < irq_count; irq_no++) {
  44                 desc = irq_to_desc(irq_list[irq_no]);
  45                 if (desc && desc->action && desc->action->name)
  46                         buf_offset += sprintf(buf + buf_offset, "%d %s\n",
  47                                         irq_list[irq_no], desc->action->name);
  48                 else
  49                         buf_offset += sprintf(buf + buf_offset, "%d\n",
  50                                         irq_list[irq_no]);
  51         }
  52         spin_unlock(&resume_reason_lock);
  53         return buf_offset;
  54 }
  55
  56 static struct kobj_attribute resume_reason = __ATTR(last_resume_reason, 0664,
  57                 reason_show, NULL);
  58
  59 static struct attribute *attrs[] = {
  60         &resume_reason.attr,
  61         NULL,
  62 };
  63 static struct attribute_group attr_group = {
  64         .attrs = attrs,
  65 };
  66
  67 /*
  68  * logs all the wake up reasons to the kernel
  69  * stores the irqs to expose them to the userspace via sysfs
  70  */
  71 void log_wakeup_reason(int irq)
  72 {
  73         struct irq_desc *desc;
  74         desc = irq_to_desc(irq);
  75         if (desc && desc->action && desc->action->name)
  76                 printk(KERN_INFO "Resume caused by IRQ %d, %s\n", irq,
  77                                 desc->action->name);
  78         else
  79                 printk(KERN_INFO "Resume caused by IRQ %d\n", irq);
  80
  81         spin_lock(&resume_reason_lock);
  82         irq_list[irq_count++] = irq;
  83         spin_unlock(&resume_reason_lock);
  84 }
  85
  86 /* Detects a suspend and clears all the previous wake up reasons*/
  87 static int wakeup_reason_pm_event(struct notifier_block *notifier,
  88                 unsigned long pm_event, void *unused)
  89 {
  90         switch (pm_event) {
  91         case PM_SUSPEND_PREPARE:
  92                 spin_lock(&resume_reason_lock);
  93                 irq_count = 0;
  94                 spin_unlock(&resume_reason_lock);
  95                 break;
  96         default:
  97                 break;
  98         }
  99         return NOTIFY_DONE;
 100 }
 101
 102 static struct notifier_block wakeup_reason_pm_notifier_block = {
 103         .notifier_call = wakeup_reason_pm_event,
 104 };
 105
 106 /* Initializes the sysfs parameter
 107  * registers the pm_event notifier
 108  */
 109 int __init wakeup_reason_init(void)
 110 {
 111         int retval;
 112         spin_lock_init(&resume_reason_lock);
 113         retval = register_pm_notifier(&wakeup_reason_pm_notifier_block);
 114         if (retval)
 115                 printk(KERN_WARNING "[%s] failed to register PM notifier %d\n",
 116                                 __func__, retval);
 117
 118         wakeup_reason = kobject_create_and_add("wakeup_reasons", kernel_kobj);
 119         if (!wakeup_reason) {
 120                 printk(KERN_WARNING "[%s] failed to create a sysfs kobject\n",
 121                                 __func__);
 122                 return 1;
 123         }
 124         retval = sysfs_create_group(wakeup_reason, &attr_group);
 125         if (retval) {
 126                 kobject_put(wakeup_reason);
 127                 printk(KERN_WARNING "[%s] failed to create a sysfs group %d\n",
 128                                 __func__, retval);
 129         }
 130         return 0;
 131 }
 132
 133 late_initcall(wakeup_reason_init);