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, fb_state == FB_STATE_STOPPED_DRAWING, HZ);
  42         if (unlikely(fb_state != FB_STATE_STOPPED_DRAWING))
  43                 pr_warn("stop_drawing_early_suspend: timeout waiting for "
  44                            "userspace to stop drawing\n");
  45 }
  46
  47 /* tell userspace to start drawing */
  48 static void start_drawing_late_resume(struct early_suspend *h)
  49 {
  50         unsigned long irq_flags;
  51
  52         spin_lock_irqsave(&fb_state_lock, irq_flags);
  53         fb_state = FB_STATE_DRAWING_OK;
  54         spin_unlock_irqrestore(&fb_state_lock, irq_flags);
  55         wake_up(&fb_state_wq);
  56 }
  57
  58 static struct early_suspend stop_drawing_early_suspend_desc = {
  59         .level = EARLY_SUSPEND_LEVEL_STOP_DRAWING,
  60         .suspend = stop_drawing_early_suspend,
  61         .resume = start_drawing_late_resume,
  62 };
  63
  64 static ssize_t wait_for_fb_sleep_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
  65 {
  66         char *s = buf;
  67         int ret;
  68
  69         ret = wait_event_interruptible(fb_state_wq, fb_state != FB_STATE_DRAWING_OK);
  70         if (ret && fb_state == FB_STATE_DRAWING_OK)
  71                 return ret;
  72         else
  73                 s += sprintf(buf, "sleeping");
  74         return s - buf;
  75 }
  76
  77 static ssize_t wait_for_fb_wake_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
  78 {
  79         char *s = buf;
  80         int ret;
  81         unsigned long irq_flags;
  82
  83         spin_lock_irqsave(&fb_state_lock, irq_flags);
  84         if (fb_state == FB_STATE_REQUEST_STOP_DRAWING) {
  85                 fb_state = FB_STATE_STOPPED_DRAWING;
  86                 wake_up(&fb_state_wq);
  87         }
  88         spin_unlock_irqrestore(&fb_state_lock, irq_flags);
  89
  90         ret = wait_event_interruptible(fb_state_wq, fb_state == FB_STATE_DRAWING_OK);
  91         if (ret && fb_state != FB_STATE_DRAWING_OK)
  92                 return ret;
  93         else
  94                 s += sprintf(buf, "awake");
  95
  96         return s - buf;
  97 }
  98
  99 #define power_ro_attr(_name) \
 100 static struct kobj_attribute _name##_attr = {   \
 101         .attr   = {                             \
 102                 .name = __stringify(_name),     \
 103                 .mode = 0444,                   \
 104         },                                      \
 105         .show   = _name##_show,                 \
 106         .store  = NULL,         \
 107 }
 108
 109 power_ro_attr(wait_for_fb_sleep);
 110 power_ro_attr(wait_for_fb_wake);
 111
 112 static struct attribute *g[] = {
 113         &wait_for_fb_sleep_attr.attr,
 114         &wait_for_fb_wake_attr.attr,
 115         NULL,
 116 };
 117
 118 static struct attribute_group attr_group = {
 119         .attrs = g,
 120 };
 121
 122 static int __init android_power_init(void)
 123 {
 124         int ret;
 125
 126         init_waitqueue_head(&fb_state_wq);
 127         fb_state = FB_STATE_DRAWING_OK;
 128
 129         ret = sysfs_create_group(power_kobj, &attr_group);
 130         if (ret) {
 131                 pr_err("android_power_init: sysfs_create_group failed\n");
 132                 return ret;
 133         }
 134
 135         register_early_suspend(&stop_drawing_early_suspend_desc);
 136         return 0;
 137 }
 138
 139 static void __exit android_power_exit(void)
 140 {
 141         unregister_early_suspend(&stop_drawing_early_suspend_desc);
 142         sysfs_remove_group(power_kobj, &attr_group);
 143 }
 144 module_init(android_power_init);
 145 module_exit(android_power_exit);