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* kernel/power/main.c - PM subsystem core functionality.
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* Copyright (c) 2003 Patrick Mochel
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* Copyright (c) 2003 Open Source Development Lab
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* This file is released under the GPLv2
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#include <linux/export.h>
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#include <linux/kobject.h>
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#include <linux/string.h>
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#include <linux/resume-trace.h>
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#include <linux/workqueue.h>
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#include <linux/debugfs.h>
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#include <linux/seq_file.h>
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DEFINE_MUTEX(pm_mutex);
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#ifdef CONFIG_PM_SLEEP
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/* Routines for PM-transition notifications */
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static BLOCKING_NOTIFIER_HEAD(pm_chain_head);
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int register_pm_notifier(struct notifier_block *nb)
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return blocking_notifier_chain_register(&pm_chain_head, nb);
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EXPORT_SYMBOL_GPL(register_pm_notifier);
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int unregister_pm_notifier(struct notifier_block *nb)
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return blocking_notifier_chain_unregister(&pm_chain_head, nb);
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EXPORT_SYMBOL_GPL(unregister_pm_notifier);
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int pm_notifier_call_chain(unsigned long val)
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int ret = blocking_notifier_call_chain(&pm_chain_head, val, NULL);
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return notifier_to_errno(ret);
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/* If set, devices may be suspended and resumed asynchronously. */
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int pm_async_enabled = 1;
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static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
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return sprintf(buf, "%d\n", pm_async_enabled);
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static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
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const char *buf, size_t n)
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if (strict_strtoul(buf, 10, &val))
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pm_async_enabled = val;
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#ifdef CONFIG_PM_DEBUG
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int pm_test_level = TEST_NONE;
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static const char * const pm_tests[__TEST_AFTER_LAST] = {
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[TEST_CPUS] = "processors",
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[TEST_PLATFORM] = "platform",
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[TEST_DEVICES] = "devices",
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[TEST_FREEZER] = "freezer",
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static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
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for (level = TEST_FIRST; level <= TEST_MAX; level++)
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if (pm_tests[level]) {
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if (level == pm_test_level)
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s += sprintf(s, "[%s] ", pm_tests[level]);
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s += sprintf(s, "%s ", pm_tests[level]);
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/* convert the last space to a newline */
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static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
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const char *buf, size_t n)
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const char * const *s;
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p = memchr(buf, '\n', n);
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len = p ? p - buf : n;
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mutex_lock(&pm_mutex);
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for (s = &pm_tests[level]; level <= TEST_MAX; s++, level++)
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if (*s && len == strlen(*s) && !strncmp(buf, *s, len)) {
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pm_test_level = level;
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mutex_unlock(&pm_mutex);
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return error ? error : n;
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#endif /* CONFIG_PM_DEBUG */
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#ifdef CONFIG_DEBUG_FS
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static char *suspend_step_name(enum suspend_stat_step step)
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case SUSPEND_PREPARE:
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case SUSPEND_SUSPEND:
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case SUSPEND_SUSPEND_NOIRQ:
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return "suspend_noirq";
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case SUSPEND_RESUME_NOIRQ:
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return "resume_noirq";
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static int suspend_stats_show(struct seq_file *s, void *unused)
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int i, index, last_dev, last_errno, last_step;
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last_dev = suspend_stats.last_failed_dev + REC_FAILED_NUM - 1;
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last_dev %= REC_FAILED_NUM;
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last_errno = suspend_stats.last_failed_errno + REC_FAILED_NUM - 1;
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last_errno %= REC_FAILED_NUM;
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last_step = suspend_stats.last_failed_step + REC_FAILED_NUM - 1;
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last_step %= REC_FAILED_NUM;
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seq_printf(s, "%s: %d\n%s: %d\n%s: %d\n%s: %d\n"
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"%s: %d\n%s: %d\n%s: %d\n%s: %d\n",
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"success", suspend_stats.success,
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"fail", suspend_stats.fail,
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"failed_freeze", suspend_stats.failed_freeze,
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"failed_prepare", suspend_stats.failed_prepare,
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"failed_suspend", suspend_stats.failed_suspend,
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"failed_suspend_noirq",
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suspend_stats.failed_suspend_noirq,
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"failed_resume", suspend_stats.failed_resume,
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"failed_resume_noirq",
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suspend_stats.failed_resume_noirq);
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seq_printf(s, "failures:\n last_failed_dev:\t%-s\n",
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suspend_stats.failed_devs[last_dev]);
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for (i = 1; i < REC_FAILED_NUM; i++) {
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index = last_dev + REC_FAILED_NUM - i;
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index %= REC_FAILED_NUM;
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seq_printf(s, "\t\t\t%-s\n",
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suspend_stats.failed_devs[index]);
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seq_printf(s, " last_failed_errno:\t%-d\n",
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suspend_stats.errno[last_errno]);
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for (i = 1; i < REC_FAILED_NUM; i++) {
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index = last_errno + REC_FAILED_NUM - i;
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index %= REC_FAILED_NUM;
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seq_printf(s, "\t\t\t%-d\n",
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suspend_stats.errno[index]);
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seq_printf(s, " last_failed_step:\t%-s\n",
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suspend_stats.failed_steps[last_step]));
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for (i = 1; i < REC_FAILED_NUM; i++) {
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index = last_step + REC_FAILED_NUM - i;
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index %= REC_FAILED_NUM;
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seq_printf(s, "\t\t\t%-s\n",
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suspend_stats.failed_steps[index]));
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static int suspend_stats_open(struct inode *inode, struct file *file)
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return single_open(file, suspend_stats_show, NULL);
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static const struct file_operations suspend_stats_operations = {
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.open = suspend_stats_open,
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.release = single_release,
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static int __init pm_debugfs_init(void)
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debugfs_create_file("suspend_stats", S_IFREG | S_IRUGO,
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NULL, NULL, &suspend_stats_operations);
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late_initcall(pm_debugfs_init);
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#endif /* CONFIG_DEBUG_FS */
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#endif /* CONFIG_PM_SLEEP */
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struct kobject *power_kobj;
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* state - control system power state.
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* show() returns what states are supported, which is hard-coded to
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* 'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
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* 'disk' (Suspend-to-Disk).
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* store() accepts one of those strings, translates it into the
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* proper enumerated value, and initiates a suspend transition.
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static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
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#ifdef CONFIG_SUSPEND
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for (i = 0; i < PM_SUSPEND_MAX; i++) {
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if (pm_states[i] && valid_state(i))
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s += sprintf(s,"%s ", pm_states[i]);
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#ifdef CONFIG_HIBERNATION
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s += sprintf(s, "%s\n", "disk");
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/* convert the last space to a newline */
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static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
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const char *buf, size_t n)
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#ifdef CONFIG_SUSPEND
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suspend_state_t state = PM_SUSPEND_STANDBY;
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const char * const *s;
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p = memchr(buf, '\n', n);
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len = p ? p - buf : n;
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/* First, check if we are requested to hibernate */
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if (len == 4 && !strncmp(buf, "disk", len)) {
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#ifdef CONFIG_SUSPEND
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for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
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if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
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if (state < PM_SUSPEND_MAX && *s) {
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error = enter_state(state);
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suspend_stats.fail++;
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dpm_save_failed_errno(error);
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suspend_stats.success++;
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return error ? error : n;
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#ifdef CONFIG_PM_SLEEP
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* The 'wakeup_count' attribute, along with the functions defined in
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* drivers/base/power/wakeup.c, provides a means by which wakeup events can be
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* handled in a non-racy way.
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* If a wakeup event occurs when the system is in a sleep state, it simply is
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* woken up. In turn, if an event that would wake the system up from a sleep
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* state occurs when it is undergoing a transition to that sleep state, the
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* transition should be aborted. Moreover, if such an event occurs when the
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* system is in the working state, an attempt to start a transition to the
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* given sleep state should fail during certain period after the detection of
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* the event. Using the 'state' attribute alone is not sufficient to satisfy
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* these requirements, because a wakeup event may occur exactly when 'state'
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* is being written to and may be delivered to user space right before it is
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* frozen, so the event will remain only partially processed until the system is
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* woken up by another event. In particular, it won't cause the transition to
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* a sleep state to be aborted.
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* This difficulty may be overcome if user space uses 'wakeup_count' before
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* writing to 'state'. It first should read from 'wakeup_count' and store
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* the read value. Then, after carrying out its own preparations for the system
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* transition to a sleep state, it should write the stored value to
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* 'wakeup_count'. If that fails, at least one wakeup event has occurred since
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* 'wakeup_count' was read and 'state' should not be written to. Otherwise, it
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* is allowed to write to 'state', but the transition will be aborted if there
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* are any wakeup events detected after 'wakeup_count' was written to.
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static ssize_t wakeup_count_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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return pm_get_wakeup_count(&val) ? sprintf(buf, "%u\n", val) : -EINTR;
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static ssize_t wakeup_count_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t n)
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if (sscanf(buf, "%u", &val) == 1) {
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if (pm_save_wakeup_count(val))
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power_attr(wakeup_count);
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#endif /* CONFIG_PM_SLEEP */
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#ifdef CONFIG_PM_TRACE
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int pm_trace_enabled;
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static ssize_t pm_trace_show(struct kobject *kobj, struct kobj_attribute *attr,
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return sprintf(buf, "%d\n", pm_trace_enabled);
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pm_trace_store(struct kobject *kobj, struct kobj_attribute *attr,
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const char *buf, size_t n)
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if (sscanf(buf, "%d", &val) == 1) {
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pm_trace_enabled = !!val;
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power_attr(pm_trace);
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static ssize_t pm_trace_dev_match_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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return show_trace_dev_match(buf, PAGE_SIZE);
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pm_trace_dev_match_store(struct kobject *kobj, struct kobj_attribute *attr,
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const char *buf, size_t n)
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power_attr(pm_trace_dev_match);
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#endif /* CONFIG_PM_TRACE */
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static struct attribute * g[] = {
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#ifdef CONFIG_PM_TRACE
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&pm_trace_dev_match_attr.attr,
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#ifdef CONFIG_PM_SLEEP
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&wakeup_count_attr.attr,
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#ifdef CONFIG_PM_DEBUG
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static struct attribute_group attr_group = {
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#ifdef CONFIG_PM_RUNTIME
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struct workqueue_struct *pm_wq;
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EXPORT_SYMBOL_GPL(pm_wq);
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static int __init pm_start_workqueue(void)
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pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0);
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return pm_wq ? 0 : -ENOMEM;
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static inline int pm_start_workqueue(void) { return 0; }
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static int __init pm_init(void)
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int error = pm_start_workqueue();
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hibernate_image_size_init();
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hibernate_reserved_size_init();
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power_kobj = kobject_create_and_add("power", NULL);
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return sysfs_create_group(power_kobj, &attr_group);
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core_initcall(pm_init);