1 /* kernel/power/earlysuspend.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/mutex.h>
19 #include <linux/rtc.h>
20 #include <linux/wakelock.h>
21 #include <linux/workqueue.h>
22
23 #include "power.h"
24
25 enum {
26 DEBUG_USER_STATE = 1U << 0,
27 DEBUG_SUSPEND = 1U << 2,
28 DEBUG_VERBOSE = 1U << 3,
29 };
30 static int debug_mask = DEBUG_USER_STATE;
31 module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
32
33 static DEFINE_MUTEX(early_suspend_lock);
34 static LIST_HEAD(early_suspend_handlers);
35 static void early_suspend(struct work_struct *work);
36 static void late_resume(struct work_struct *work);
37 static DECLARE_WORK(early_suspend_work, early_suspend);
38 static DECLARE_WORK(late_resume_work, late_resume);
39 static DEFINE_SPINLOCK(state_lock);
40 enum {
41 SUSPEND_REQUESTED = 0x1,
42 SUSPENDED = 0x2,
43 SUSPEND_REQUESTED_AND_SUSPENDED = SUSPEND_REQUESTED | SUSPENDED,
44 };
45 static int state;
46
47 void register_early_suspend(struct early_suspend *handler)
48 {
49 struct list_head *pos;
50
51 mutex_lock(&early_suspend_lock);
52 list_for_each(pos, &early_suspend_handlers) {
53 struct early_suspend *e;
54 e = list_entry(pos, struct early_suspend, link);
55 if (e->level > handler->level)
56 break;
57 }
58 list_add_tail(&handler->link, pos);
59 if ((state & SUSPENDED) && handler->suspend)
60 handler->suspend(handler);
61 mutex_unlock(&early_suspend_lock);
62 }
63 EXPORT_SYMBOL(register_early_suspend);
64
65 void unregister_early_suspend(struct early_suspend *handler)
66 {
67 mutex_lock(&early_suspend_lock);
68 list_del(&handler->link);
69 mutex_unlock(&early_suspend_lock);
70 }
71 EXPORT_SYMBOL(unregister_early_suspend);
72
register_early_suspend(struct early_suspend *handler)会按照level从小到大的方式，将handler依次挂在early_suspend_handlers链表头上。
if (e->level > handler->level)判断链表节点e的level大于要插入的handler的level时就break当前遍历，用list_add_tail(&handler->link, pos);将handler->link插到pos节点的前面。
73 static void early_suspend(struct work_struct *work)
74 {
75 struct early_suspend *pos;
76 unsigned long irqflags;
77 int abort = 0;
78
79 mutex_lock(&early_suspend_lock);
80 spin_lock_irqsave(&state_lock, irqflags);
81 if (state == SUSPEND_REQUESTED)
82 state |= SUSPENDED;
83 else
84 abort = 1;
85 spin_unlock_irqrestore(&state_lock, irqflags);
86
87 if (abort) {
88 if (debug_mask & DEBUG_SUSPEND)
89 pr_info("early_suspend: abort, state %d
", state);
90 mutex_unlock(&early_suspend_lock);
91 goto abort;
92 }
93
94 if (debug_mask & DEBUG_SUSPEND)
95 pr_info("early_suspend: call handlers
");
96 list_for_each_entry(pos, &early_suspend_handlers, link) {
97 if (pos->suspend != NULL) {
98 if (debug_mask & DEBUG_VERBOSE)
99 pr_info("early_suspend: calling %pf
", pos->suspend);
100 pos->suspend(pos);
101 }
102 }
103 mutex_unlock(&early_suspend_lock);
104
105 suspend_sys_sync_queue();
106 abort:
107 spin_lock_irqsave(&state_lock, irqflags);
108 if (state == SUSPEND_REQUESTED_AND_SUSPENDED)
109 wake_unlock(&main_wake_lock);
110 spin_unlock_irqrestore(&state_lock, irqflags);
111 }
112
113 static void late_resume(struct work_struct *work)
114 {
115 struct early_suspend *pos;
116 unsigned long irqflags;
117 int abort = 0;
118
119 mutex_lock(&early_suspend_lock);
120 spin_lock_irqsave(&state_lock, irqflags);
121 if (state == SUSPENDED)
122 state &= ~SUSPENDED;
123 else
124 abort = 1;
125 spin_unlock_irqrestore(&state_lock, irqflags);
126
127 if (abort) {
128 if (debug_mask & DEBUG_SUSPEND)
129 pr_info("late_resume: abort, state %d
", state);
130 goto abort;
131 }
132 if (debug_mask & DEBUG_SUSPEND)
133 pr_info("late_resume: call handlers
");
134 list_for_each_entry_reverse(pos, &early_suspend_handlers, link) {
135 if (pos->resume != NULL) {
136 if (debug_mask & DEBUG_VERBOSE)
137 pr_info("late_resume: calling %pf
", pos->resume);
138
139 pos->resume(pos);
140 }
141 }
142 if (debug_mask & DEBUG_SUSPEND)
143 pr_info("late_resume: done
");
144 abort:
145 mutex_unlock(&early_suspend_lock);
146 }
147
early_suspend(struct work_struct *work)和late_resume(struct work_struct *work)分别在第37、38行被声明为了early_suspend_work和late_resume_work，以便在
request_suspend_state(suspend_state_t new_state)中的suspend_work_queue工作队列中使用。
ealry_suspend(struct work_struct *work)中最关键的一句list_for_each_entry(pos, &early_suspend_handlers, link)，表示按照level等级排列的顺序，依次调用pos所指向的各个
驱动中注册的ealrysuspend 指向的suspend handler。
late_resume(struct work_struct *work)中list_for_each_entry_reverse(pos, &early_suspend_handlers, link)，表示按照level等级的逆序，依次调用pos所指向的各个
驱动中注册的earlysuspend 指向的resume handler。
这里有一个很有用的调试信息：pr_info("late_resume: calling %pf
", pos->resume); %pf可以打印被调函数的函数名。
148 void request_suspend_state(suspend_state_t new_state)
149 {
150 unsigned long irqflags;
151 int old_sleep;
152
153 spin_lock_irqsave(&state_lock, irqflags);
154 old_sleep = state & SUSPEND_REQUESTED;
155 if (debug_mask & DEBUG_USER_STATE) {
156 struct timespec ts;
157 struct rtc_time tm;
158 getnstimeofday(&ts);
159 rtc_time_to_tm(ts.tv_sec, &tm);
160 pr_info("request_suspend_state: %s (%d->%d) at %lld "
161 "(%d-%02d-%02d %02d:%02d:%02d.%09lu UTC)
",
162 new_state != PM_SUSPEND_ON ? "sleep" : "wakeup",
163 requested_suspend_state, new_state,
164 ktime_to_ns(ktime_get()),
165 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
166 tm.tm_hour, tm.tm_min, tm.tm_sec, ts.tv_nsec);
167 }
168 if (!old_sleep && new_state != PM_SUSPEND_ON) {
169 state |= SUSPEND_REQUESTED;
170 queue_work(suspend_work_queue, &early_suspend_work);
171 } else if (old_sleep && new_state == PM_SUSPEND_ON) {
172 state &= ~SUSPEND_REQUESTED;
173 wake_lock(&main_wake_lock);
174 queue_work(suspend_work_queue, &late_resume_work);
175 }
176 requested_suspend_state = new_state;
177 spin_unlock_irqrestore(&state_lock, irqflags);
178 }
179
180 suspend_state_t get_suspend_state(void)
181 {
182 return requested_suspend_state;
183 }
request_suspend_state(suspend_state_t new_state)会被kernel/power/main.c中的state show调用，main.c将会在下一章详细说明。
request_suspend_state(suspend_state_t new_state)传入的参数new_state的类型suspend_state_t为一个typedef类型的变量：typedef int __bitwise suspend_state_t;
当new_state为0时，request_suspend_state调用queue_work(suspend_work_queue, &late_resume_work);分支进行late唤醒。
当new_state为3时，request_suspend_state调用queue_work(suspend_work_queue, &early_suspend_work);分支进行浅度休眠。
当系统休眠/唤醒时，串口上会出现如下打印：
request_suspend_state: sleep (0->3) at 6442598858519 (2012-02-05 01:31:08.172285684 UTC)
request_suspend_state: wakeup (3->0) at 6464854624023 (2012-02-05 01:31:30.428053438 UTC)
0代表唤醒，3代表休眠。
0->3 从唤醒到休眠(sleep);
3->0 从休眠到唤醒(wakeup);