kernel/power/fbearlysuspend.c

   1 /* kernel/power/fbearlysuspend.c
   2  *
   3  * Copyright (C) 2005-2008 Google, Inc.
   4  *
   5  * This software is licensed under the terms of the GNU General Public
   6  * License version 2, as published by the Free Software Foundation, and
   7  * may be copied, distributed, and modified under those terms.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  */
  15
  16 #include <linux/earlysuspend.h>
  17 #include <linux/module.h>
  18 #include <linux/wait.h>
  19
  20 #include "power.h"
  21
  22 static wait_queue_head_t fb_state_wq;
  23 static DEFINE_SPINLOCK(fb_state_lock);
  24 static enum {
  25         FB_STATE_STOPPED_DRAWING,
  26         FB_STATE_REQUEST_STOP_DRAWING,
  27         FB_STATE_DRAWING_OK,
  28 } fb_state;
  29
  30 /* tell userspace to stop drawing, wait for it to stop */
  31 static void stop_drawing_early_suspend(struct early_suspend *h)
  32 {
  33         int ret;
  34         unsigned long irq_flags;
  35
  36         spin_lock_irqsave(&fb_state_lock, irq_flags);
  37         fb_state = FB_STATE_REQUEST_STOP_DRAWING;
  38         spin_unlock_irqrestore(&fb_state_lock, irq_flags);
  39
  40         wake_up_all(&fb_state_wq);
  41         ret = wait_event_timeout(fb_state_wq,
  42                                  fb_state == FB_STATE_STOPPED_DRAWING,
  43                                  HZ);
  44         if (unlikely(fb_state != FB_STATE_STOPPED_DRAWING))
  45                 pr_warning("stop_drawing_early_suspend: timeout waiting for "
  46                            "userspace to stop drawing\n");
  47 }
  48
  49 /* tell userspace to start drawing */
  50 static void start_drawing_late_resume(struct early_suspend *h)
  51 {
  52         unsigned long irq_flags;
  53
  54         spin_lock_irqsave(&fb_state_lock, irq_flags);
  55         fb_state = FB_STATE_DRAWING_OK;
  56         spin_unlock_irqrestore(&fb_state_lock, irq_flags);
  57         wake_up(&fb_state_wq);
  58 }
  59
  60 static struct early_suspend stop_drawing_early_suspend_desc = {
  61         .level = EARLY_SUSPEND_LEVEL_STOP_DRAWING,
  62         .suspend = stop_drawing_early_suspend,
  63         .resume = start_drawing_late_resume,
  64 };
  65
  66 static ssize_t wait_for_fb_sleep_show(struct kobject *kobj,
  67                                       struct kobj_attribute *attr, char *buf)
  68 {
  69         char *s = buf;
  70         int ret;
  71
  72         ret = wait_event_interruptible(fb_state_wq,
  73                                        fb_state != FB_STATE_DRAWING_OK);
  74         if (ret && fb_state == FB_STATE_DRAWING_OK)
  75                 return ret;
  76         else
  77                 s += sprintf(buf, "sleeping");
  78         return s - buf;
  79 }
  80
  81 static ssize_t wait_for_fb_wake_show(struct kobject *kobj,
  82                                      struct kobj_attribute *attr, char *buf)
  83 {
  84         char *s = buf;
  85         int ret;
  86         unsigned long irq_flags;
  87
  88         spin_lock_irqsave(&fb_state_lock, irq_flags);
  89         if (fb_state == FB_STATE_REQUEST_STOP_DRAWING) {
  90                 fb_state = FB_STATE_STOPPED_DRAWING;
  91                 wake_up(&fb_state_wq);
  92         }
  93         spin_unlock_irqrestore(&fb_state_lock, irq_flags);
  94
  95         ret = wait_event_interruptible(fb_state_wq,
  96                                        fb_state == FB_STATE_DRAWING_OK);
  97         if (ret && fb_state != FB_STATE_DRAWING_OK)
  98                 return ret;
  99         else
 100                 s += sprintf(buf, "awake");
 101
 102         return s - buf;
 103 }
 104
 105 #define power_ro_attr(_name) \
 106 static struct kobj_attribute _name##_attr = {   \
 107         .attr   = {                             \
 108                 .name = __stringify(_name),     \
 109                 .mode = 0444,                   \
 110         },                                      \
 111         .show   = _name##_show,                 \
 112         .store  = NULL,         \
 113 }
 114
 115 power_ro_attr(wait_for_fb_sleep);
 116 power_ro_attr(wait_for_fb_wake);
 117
 118 static struct attribute *g[] = {
 119         &wait_for_fb_sleep_attr.attr,
 120         &wait_for_fb_wake_attr.attr,
 121         NULL,
 122 };
 123
 124 static struct attribute_group attr_group = {
 125         .attrs = g,
 126 };
 127
 128 static int __init android_power_init(void)
 129 {
 130         int ret;
 131
 132         init_waitqueue_head(&fb_state_wq);
 133         fb_state = FB_STATE_DRAWING_OK;
 134
 135         ret = sysfs_create_group(power_kobj, &attr_group);
 136         if (ret) {
 137                 pr_err("android_power_init: sysfs_create_group failed\n");
 138                 return ret;
 139         }
 140
 141         register_early_suspend(&stop_drawing_early_suspend_desc);
 142         return 0;
 143 }
 144
 145 static void  __exit android_power_exit(void)
 146 {
 147         unregister_early_suspend(&stop_drawing_early_suspend_desc);
 148         sysfs_remove_group(power_kobj, &attr_group);
 149 }
 150
 151 module_init(android_power_init);
 152 module_exit(android_power_exit);
 153