power命令_kernel power41

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 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\n", 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\n"); 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\n", 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\n", state); 130 goto abort; 131 } 132 if (debug_mask & DEBUG_SUSPEND) 133 pr_info("late_resume: call handlers\n"); 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\n", pos->resume); 138 139 pos->resume(pos); 140 } 141 } 142 if (debug_mask & DEBUG_SUSPEND) 143 pr_info("late_resume: done\n"); 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\n", 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)\n", 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);