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 #ifdef CONFIG_PM_SLEEP
  21
  22 /* Routines for PM-transition notifications */
  23
  24 static BLOCKING_NOTIFIER_HEAD(pm_chain_head);
  25
  26 int register_pm_notifier(struct notifier_block *nb)
  27 {
  28         return blocking_notifier_chain_register(&pm_chain_head, nb);
  29 }
  30 EXPORT_SYMBOL_GPL(register_pm_notifier);
  31
  32 int unregister_pm_notifier(struct notifier_block *nb)
  33 {
  34         return blocking_notifier_chain_unregister(&pm_chain_head, nb);
  35 }
  36 EXPORT_SYMBOL_GPL(unregister_pm_notifier);
  37
  38 int pm_notifier_call_chain(unsigned long val)
  39 {
  40         return (blocking_notifier_call_chain(&pm_chain_head, val, NULL)
  41                         == NOTIFY_BAD) ? -EINVAL : 0;
  42 }
  43
  44 /* If set, devices may be suspended and resumed asynchronously. */
  45 int pm_async_enabled = 1;
  46
  47 static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
  48                              char *buf)
  49 {
  50         return sprintf(buf, "%d\n", pm_async_enabled);
  51 }
  52
  53 static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
  54                               const char *buf, size_t n)
  55 {
  56         unsigned long val;
  57
  58         if (strict_strtoul(buf, 10, &val))
  59                 return -EINVAL;
  60
  61         if (val > 1)
  62                 return -EINVAL;
  63
  64         pm_async_enabled = val;
  65         return n;
  66 }
  67
  68 power_attr(pm_async);
  69
  70 #ifdef CONFIG_PM_DEBUG
  71 int pm_test_level = TEST_NONE;
  72
  73 static const char * const pm_tests[__TEST_AFTER_LAST] = {
  74         [TEST_NONE] = "none",
  75         [TEST_CORE] = "core",
  76         [TEST_CPUS] = "processors",
  77         [TEST_PLATFORM] = "platform",
  78         [TEST_DEVICES] = "devices",
  79         [TEST_FREEZER] = "freezer",
  80 };
  81
  82 static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
  83                                 char *buf)
  84 {
  85         char *s = buf;
  86         int level;
  87
  88         for (level = TEST_FIRST; level <= TEST_MAX; level++)
  89                 if (pm_tests[level]) {
  90                         if (level == pm_test_level)
  91                                 s += sprintf(s, "[%s] ", pm_tests[level]);
  92                         else
  93                                 s += sprintf(s, "%s ", pm_tests[level]);
  94                 }
  95
  96         if (s != buf)
  97                 /* convert the last space to a newline */
  98                 *(s-1) = '\n';
  99
 100         return (s - buf);
 101 }
 102
 103 static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
 104                                 const char *buf, size_t n)
 105 {
 106         const char * const *s;
 107         int level;
 108         char *p;
 109         int len;
 110         int error = -EINVAL;
 111
 112         p = memchr(buf, '\n', n);
 113         len = p ? p - buf : n;
 114
 115         mutex_lock(&pm_mutex);
 116
 117         level = TEST_FIRST;
 118         for (s = &pm_tests[level]; level <= TEST_MAX; s++, level++)
 119                 if (*s && len == strlen(*s) && !strncmp(buf, *s, len)) {
 120                         pm_test_level = level;
 121                         error = 0;
 122                         break;
 123                 }
 124
 125         mutex_unlock(&pm_mutex);
 126
 127         return error ? error : n;
 128 }
 129
 130 power_attr(pm_test);
 131 #endif /* CONFIG_PM_DEBUG */
 132
 133 #endif /* CONFIG_PM_SLEEP */
 134
 135 struct kobject *power_kobj;
 136
 137 /**
 138  *      state - control system power state.
 139  *
 140  *      show() returns what states are supported, which is hard-coded to
 141  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 142  *      'disk' (Suspend-to-Disk).
 143  *
 144  *      store() accepts one of those strings, translates it into the
 145  *      proper enumerated value, and initiates a suspend transition.
 146  */
 147 static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
 148                           char *buf)
 149 {
 150         char *s = buf;
 151 #ifdef CONFIG_SUSPEND
 152         int i;
 153
 154         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 155                 if (pm_states[i] && valid_state(i))
 156                         s += sprintf(s,"%s ", pm_states[i]);
 157         }
 158 #endif
 159 #ifdef CONFIG_HIBERNATION
 160         s += sprintf(s, "%s\n", "disk");
 161 #else
 162         if (s != buf)
 163                 /* convert the last space to a newline */
 164                 *(s-1) = '\n';
 165 #endif
 166         return (s - buf);
 167 }
 168
 169 static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 170                            const char *buf, size_t n)
 171 {
 172 #ifdef CONFIG_SUSPEND
 173         suspend_state_t state = PM_SUSPEND_STANDBY;
 174         const char * const *s;
 175 #endif
 176         char *p;
 177         int len;
 178         int error = -EINVAL;
 179
 180         p = memchr(buf, '\n', n);
 181         len = p ? p - buf : n;
 182
 183         /* First, check if we are requested to hibernate */
 184         if (len == 4 && !strncmp(buf, "disk", len)) {
 185                 error = hibernate();
 186   goto Exit;
 187         }
 188
 189 #ifdef CONFIG_SUSPEND
 190         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 191                 if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
 192                         break;
 193         }
 194         if (state < PM_SUSPEND_MAX && *s)
 195                 error = enter_state(state);
 196 #endif
 197
 198  Exit:
 199         return error ? error : n;
 200 }
 201
 202 power_attr(state);
 203
 204 #ifdef CONFIG_PM_SLEEP
 205 /*
 206  * The 'wakeup_count' attribute, along with the functions defined in
 207  * drivers/base/power/wakeup.c, provides a means by which wakeup events can be
 208  * handled in a non-racy way.
 209  *
 210  * If a wakeup event occurs when the system is in a sleep state, it simply is
 211  * woken up.  In turn, if an event that would wake the system up from a sleep
 212  * state occurs when it is undergoing a transition to that sleep state, the
 213  * transition should be aborted.  Moreover, if such an event occurs when the
 214  * system is in the working state, an attempt to start a transition to the
 215  * given sleep state should fail during certain period after the detection of
 216  * the event.  Using the 'state' attribute alone is not sufficient to satisfy
 217  * these requirements, because a wakeup event may occur exactly when 'state'
 218  * is being written to and may be delivered to user space right before it is
 219  * frozen, so the event will remain only partially processed until the system is
 220  * woken up by another event.  In particular, it won't cause the transition to
 221  * a sleep state to be aborted.
 222  *
 223  * This difficulty may be overcome if user space uses 'wakeup_count' before
 224  * writing to 'state'.  It first should read from 'wakeup_count' and store
 225  * the read value.  Then, after carrying out its own preparations for the system
 226  * transition to a sleep state, it should write the stored value to
 227  * 'wakeup_count'.  If that fails, at least one wakeup event has occurred since
 228  * 'wakeup_count' was read and 'state' should not be written to.  Otherwise, it
 229  * is allowed to write to 'state', but the transition will be aborted if there
 230  * are any wakeup events detected after 'wakeup_count' was written to.
 231  */
 232
 233 static ssize_t wakeup_count_show(struct kobject *kobj,
 234                                 struct kobj_attribute *attr,
 235                                 char *buf)
 236 {
 237         unsigned int val;
 238
 239         return pm_get_wakeup_count(&val) ? sprintf(buf, "%u\n", val) : -EINTR;
 240 }
 241
 242 static ssize_t wakeup_count_store(struct kobject *kobj,
 243                                 struct kobj_attribute *attr,
 244                                 const char *buf, size_t n)
 245 {
 246         unsigned int val;
 247
 248         if (sscanf(buf, "%u", &val) == 1) {
 249                 if (pm_save_wakeup_count(val))
 250                         return n;
 251         }
 252         return -EINVAL;
 253 }
 254
 255 power_attr(wakeup_count);
 256 #endif /* CONFIG_PM_SLEEP */
 257
 258 #ifdef CONFIG_PM_TRACE
 259 int pm_trace_enabled;
 260
 261 static ssize_t pm_trace_show(struct kobject *kobj, struct kobj_attribute *attr,
 262                              char *buf)
 263 {
 264         return sprintf(buf, "%d\n", pm_trace_enabled);
 265 }
 266
 267 static ssize_t
 268 pm_trace_store(struct kobject *kobj, struct kobj_attribute *attr,
 269                const char *buf, size_t n)
 270 {
 271         int val;
 272
 273         if (sscanf(buf, "%d", &val) == 1) {
 274                 pm_trace_enabled = !!val;
 275                 return n;
 276         }
 277         return -EINVAL;
 278 }
 279
 280 power_attr(pm_trace);
 281
 282 static ssize_t pm_trace_dev_match_show(struct kobject *kobj,
 283                                        struct kobj_attribute *attr,
 284                                        char *buf)
 285 {
 286         return show_trace_dev_match(buf, PAGE_SIZE);
 287 }
 288
 289 static ssize_t
 290 pm_trace_dev_match_store(struct kobject *kobj, struct kobj_attribute *attr,
 291                          const char *buf, size_t n)
 292 {
 293         return -EINVAL;
 294 }
 295
 296 power_attr(pm_trace_dev_match);
 297
 298 #endif /* CONFIG_PM_TRACE */
 299
 300 static struct attribute * g[] = {
 301         &state_attr.attr,
 302 #ifdef CONFIG_PM_TRACE
 303         &pm_trace_attr.attr,
 304         &pm_trace_dev_match_attr.attr,
 305 #endif
 306 #ifdef CONFIG_PM_SLEEP
 307         &pm_async_attr.attr,
 308         &wakeup_count_attr.attr,
 309 #ifdef CONFIG_PM_DEBUG
 310         &pm_test_attr.attr,
 311 #endif
 312 #endif
 313         NULL,
 314 };
 315
 316 static struct attribute_group attr_group = {
 317         .attrs = g,
 318 };
 319
 320 #ifdef CONFIG_PM_RUNTIME
 321 struct workqueue_struct *pm_wq;
 322 EXPORT_SYMBOL_GPL(pm_wq);
 323
 324 static int __init pm_start_workqueue(void)
 325 {
 326         pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0);
 327
 328         return pm_wq ? 0 : -ENOMEM;
 329 }
 330 #else
 331 static inline int pm_start_workqueue(void) { return 0; }
 332 #endif
 333
 334 static int __init pm_init(void)
 335 {
 336         int error = pm_start_workqueue();
 337         if (error)
 338                 return error;
 339         hibernate_image_size_init();
 340         power_kobj = kobject_create_and_add("power", NULL);
 341         if (!power_kobj)
 342                 return -ENOMEM;
 343         return sysfs_create_group(power_kobj, &attr_group);
 344 }
 345
 346 core_initcall(pm_init);