kernel/power/main.c

   1 /*
   2  * kernel/power/main.c - PM subsystem core functionality.
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Open Source Development Lab
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  */
  10
  11 #include <linux/kobject.h>
  12 #include <linux/string.h>
  13 #include <linux/resume-trace.h>
  14 #include <linux/workqueue.h>
  15
  16 #include "power.h"
  17
  18 DEFINE_MUTEX(pm_mutex);
  19
  20 unsigned int pm_flags;
  21 EXPORT_SYMBOL(pm_flags);
  22
  23 #ifdef CONFIG_PM_SLEEP
  24
  25 /* Routines for PM-transition notifications */
  26
  27 static BLOCKING_NOTIFIER_HEAD(pm_chain_head);
  28
  29 int register_pm_notifier(struct notifier_block *nb)
  30 {
  31         return blocking_notifier_chain_register(&pm_chain_head, nb);
  32 }
  33 EXPORT_SYMBOL_GPL(register_pm_notifier);
  34
  35 int unregister_pm_notifier(struct notifier_block *nb)
  36 {
  37         return blocking_notifier_chain_unregister(&pm_chain_head, nb);
  38 }
  39 EXPORT_SYMBOL_GPL(unregister_pm_notifier);
  40
  41 int pm_notifier_call_chain(unsigned long val)
  42 {
  43         return (blocking_notifier_call_chain(&pm_chain_head, val, NULL)
  44                         == NOTIFY_BAD) ? -EINVAL : 0;
  45 }
  46
  47 /* If set, devices may be suspended and resumed asynchronously. */
  48 int pm_async_enabled = 1;
  49
  50 static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
  51                              char *buf)
  52 {
  53         return sprintf(buf, "%d\n", pm_async_enabled);
  54 }
  55
  56 static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
  57                               const char *buf, size_t n)
  58 {
  59         unsigned long val;
  60
  61         if (strict_strtoul(buf, 10, &val))
  62                 return -EINVAL;
  63
  64         if (val > 1)
  65                 return -EINVAL;
  66
  67         pm_async_enabled = val;
  68         return n;
  69 }
  70
  71 power_attr(pm_async);
  72
  73 #ifdef CONFIG_PM_DEBUG
  74 int pm_test_level = TEST_NONE;
  75
  76 static const char * const pm_tests[__TEST_AFTER_LAST] = {
  77         [TEST_NONE] = "none",
  78         [TEST_CORE] = "core",
  79         [TEST_CPUS] = "processors",
  80         [TEST_PLATFORM] = "platform",
  81         [TEST_DEVICES] = "devices",
  82         [TEST_FREEZER] = "freezer",
  83 };
  84
  85 static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
  86                                 char *buf)
  87 {
  88         char *s = buf;
  89         int level;
  90
  91         for (level = TEST_FIRST; level <= TEST_MAX; level++)
  92                 if (pm_tests[level]) {
  93                         if (level == pm_test_level)
  94                                 s += sprintf(s, "[%s] ", pm_tests[level]);
  95                         else
  96                                 s += sprintf(s, "%s ", pm_tests[level]);
  97                 }
  98
  99         if (s != buf)
 100                 /* convert the last space to a newline */
 101                 *(s-1) = '\n';
 102
 103         return (s - buf);
 104 }
 105
 106 static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
 107                                 const char *buf, size_t n)
 108 {
 109         const char * const *s;
 110         int level;
 111         char *p;
 112         int len;
 113         int error = -EINVAL;
 114
 115         p = memchr(buf, '\n', n);
 116         len = p ? p - buf : n;
 117
 118         mutex_lock(&pm_mutex);
 119
 120         level = TEST_FIRST;
 121         for (s = &pm_tests[level]; level <= TEST_MAX; s++, level++)
 122                 if (*s && len == strlen(*s) && !strncmp(buf, *s, len)) {
 123                         pm_test_level = level;
 124                         error = 0;
 125                         break;
 126                 }
 127
 128         mutex_unlock(&pm_mutex);
 129
 130         return error ? error : n;
 131 }
 132
 133 power_attr(pm_test);
 134 #endif /* CONFIG_PM_DEBUG */
 135
 136 #endif /* CONFIG_PM_SLEEP */
 137
 138 struct kobject *power_kobj;
 139
 140 /**
 141  *      state - control system power state.
 142  *
 143  *      show() returns what states are supported, which is hard-coded to
 144  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 145  *      'disk' (Suspend-to-Disk).
 146  *
 147  *      store() accepts one of those strings, translates it into the
 148  *      proper enumerated value, and initiates a suspend transition.
 149  */
 150 static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
 151                           char *buf)
 152 {
 153         char *s = buf;
 154 #ifdef CONFIG_SUSPEND
 155         int i;
 156
 157         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 158                 if (pm_states[i] && valid_state(i))
 159                         s += sprintf(s,"%s ", pm_states[i]);
 160         }
 161 #endif
 162 #ifdef CONFIG_HIBERNATION
 163         s += sprintf(s, "%s\n", "disk");
 164 #else
 165         if (s != buf)
 166                 /* convert the last space to a newline */
 167                 *(s-1) = '\n';
 168 #endif
 169         return (s - buf);
 170 }
 171
 172 static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 173                            const char *buf, size_t n)
 174 {
 175 #ifdef CONFIG_SUSPEND
 176         suspend_state_t state = PM_SUSPEND_STANDBY;
 177         const char * const *s;
 178 #endif
 179         char *p;
 180         int len;
 181         int error = -EINVAL;
 182
 183         p = memchr(buf, '\n', n);
 184         len = p ? p - buf : n;
 185
 186         /* First, check if we are requested to hibernate */
 187         if (len == 4 && !strncmp(buf, "disk", len)) {
 188                 error = hibernate();
 189   goto Exit;
 190         }
 191
 192 #ifdef CONFIG_SUSPEND
 193         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 194                 if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
 195                         break;
 196         }
 197         if (state < PM_SUSPEND_MAX && *s)
 198                 error = enter_state(state);
 199 #endif
 200
 201  Exit:
 202         return error ? error : n;
 203 }
 204
 205 power_attr(state);
 206
 207 #ifdef CONFIG_PM_SLEEP
 208 /*
 209  * The 'wakeup_count' attribute, along with the functions defined in
 210  * drivers/base/power/wakeup.c, provides a means by which wakeup events can be
 211  * handled in a non-racy way.
 212  *
 213  * If a wakeup event occurs when the system is in a sleep state, it simply is
 214  * woken up.  In turn, if an event that would wake the system up from a sleep
 215  * state occurs when it is undergoing a transition to that sleep state, the
 216  * transition should be aborted.  Moreover, if such an event occurs when the
 217  * system is in the working state, an attempt to start a transition to the
 218  * given sleep state should fail during certain period after the detection of
 219  * the event.  Using the 'state' attribute alone is not sufficient to satisfy
 220  * these requirements, because a wakeup event may occur exactly when 'state'
 221  * is being written to and may be delivered to user space right before it is
 222  * frozen, so the event will remain only partially processed until the system is
 223  * woken up by another event.  In particular, it won't cause the transition to
 224  * a sleep state to be aborted.
 225  *
 226  * This difficulty may be overcome if user space uses 'wakeup_count' before
 227  * writing to 'state'.  It first should read from 'wakeup_count' and store
 228  * the read value.  Then, after carrying out its own preparations for the system
 229  * transition to a sleep state, it should write the stored value to
 230  * 'wakeup_count'.  If that fails, at least one wakeup event has occured since
 231  * 'wakeup_count' was read and 'state' should not be written to.  Otherwise, it
 232  * is allowed to write to 'state', but the transition will be aborted if there
 233  * are any wakeup events detected after 'wakeup_count' was written to.
 234  */
 235
 236 static ssize_t wakeup_count_show(struct kobject *kobj,
 237                                 struct kobj_attribute *attr,
 238                                 char *buf)
 239 {
 240         unsigned long val;
 241
 242         return pm_get_wakeup_count(&val) ? sprintf(buf, "%lu\n", val) : -EINTR;
 243 }
 244
 245 static ssize_t wakeup_count_store(struct kobject *kobj,
 246                                 struct kobj_attribute *attr,
 247                                 const char *buf, size_t n)
 248 {
 249         unsigned long val;
 250
 251         if (sscanf(buf, "%lu", &val) == 1) {
 252                 if (pm_save_wakeup_count(val))
 253                         return n;
 254         }
 255         return -EINVAL;
 256 }
 257
 258 power_attr(wakeup_count);
 259 #endif /* CONFIG_PM_SLEEP */
 260
 261 #ifdef CONFIG_PM_TRACE
 262 int pm_trace_enabled;
 263
 264 static ssize_t pm_trace_show(struct kobject *kobj, struct kobj_attribute *attr,
 265                              char *buf)
 266 {
 267         return sprintf(buf, "%d\n", pm_trace_enabled);
 268 }
 269
 270 static ssize_t
 271 pm_trace_store(struct kobject *kobj, struct kobj_attribute *attr,
 272                const char *buf, size_t n)
 273 {
 274         int val;
 275
 276         if (sscanf(buf, "%d", &val) == 1) {
 277                 pm_trace_enabled = !!val;
 278                 return n;
 279         }
 280         return -EINVAL;
 281 }
 282
 283 power_attr(pm_trace);
 284 #endif /* CONFIG_PM_TRACE */
 285
 286 static struct attribute * g[] = {
 287         &state_attr.attr,
 288 #ifdef CONFIG_PM_TRACE
 289         &pm_trace_attr.attr,
 290 #endif
 291 #ifdef CONFIG_PM_SLEEP
 292         &pm_async_attr.attr,
 293         &wakeup_count_attr.attr,
 294 #ifdef CONFIG_PM_DEBUG
 295         &pm_test_attr.attr,
 296 #endif
 297 #endif
 298         NULL,
 299 };
 300
 301 static struct attribute_group attr_group = {
 302         .attrs = g,
 303 };
 304
 305 #ifdef CONFIG_PM_RUNTIME
 306 struct workqueue_struct *pm_wq;
 307 EXPORT_SYMBOL_GPL(pm_wq);
 308
 309 static int __init pm_start_workqueue(void)
 310 {
 311         pm_wq = create_freezeable_workqueue("pm");
 312
 313         return pm_wq ? 0 : -ENOMEM;
 314 }
 315 #else
 316 static inline int pm_start_workqueue(void) { return 0; }
 317 #endif
 318
 319 static int __init pm_init(void)
 320 {
 321         int error = pm_start_workqueue();
 322         if (error)
 323                 return error;
 324         power_kobj = kobject_create_and_add("power", NULL);
 325         if (!power_kobj)
 326                 return -ENOMEM;
 327         return sysfs_create_group(power_kobj, &attr_group);
 328 }
 329
 330 core_initcall(pm_init);