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/export.h>
  12 #include <linux/kobject.h>
  13 #include <linux/string.h>
  14 #include <linux/resume-trace.h>
  15 #include <linux/workqueue.h>
  16
  17 #include "power.h"
  18
  19 DEFINE_MUTEX(pm_mutex);
  20
  21 #ifdef CONFIG_PM_SLEEP
  22
  23 /* Routines for PM-transition notifications */
  24
  25 static BLOCKING_NOTIFIER_HEAD(pm_chain_head);
  26
  27 int register_pm_notifier(struct notifier_block *nb)
  28 {
  29         return blocking_notifier_chain_register(&pm_chain_head, nb);
  30 }
  31 EXPORT_SYMBOL_GPL(register_pm_notifier);
  32
  33 int unregister_pm_notifier(struct notifier_block *nb)
  34 {
  35         return blocking_notifier_chain_unregister(&pm_chain_head, nb);
  36 }
  37 EXPORT_SYMBOL_GPL(unregister_pm_notifier);
  38
  39 int pm_notifier_call_chain(unsigned long val)
  40 {
  41         int ret = blocking_notifier_call_chain(&pm_chain_head, val, NULL);
  42
  43         return notifier_to_errno(ret);
  44 }
  45
  46 /* If set, devices may be suspended and resumed asynchronously. */
  47 int pm_async_enabled = 1;
  48
  49 static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
  50                              char *buf)
  51 {
  52         return sprintf(buf, "%d\n", pm_async_enabled);
  53 }
  54
  55 static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
  56                               const char *buf, size_t n)
  57 {
  58         unsigned long val;
  59
  60         if (strict_strtoul(buf, 10, &val))
  61                 return -EINVAL;
  62
  63         if (val > 1)
  64                 return -EINVAL;
  65
  66         pm_async_enabled = val;
  67         return n;
  68 }
  69
  70 power_attr(pm_async);
  71
  72 #ifdef CONFIG_PM_DEBUG
  73 int pm_test_level = TEST_NONE;
  74
  75 static const char * const pm_tests[__TEST_AFTER_LAST] = {
  76         [TEST_NONE] = "none",
  77         [TEST_CORE] = "core",
  78         [TEST_CPUS] = "processors",
  79         [TEST_PLATFORM] = "platform",
  80         [TEST_DEVICES] = "devices",
  81         [TEST_FREEZER] = "freezer",
  82 };
  83
  84 static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
  85                                 char *buf)
  86 {
  87         char *s = buf;
  88         int level;
  89
  90         for (level = TEST_FIRST; level <= TEST_MAX; level++)
  91                 if (pm_tests[level]) {
  92                         if (level == pm_test_level)
  93                                 s += sprintf(s, "[%s] ", pm_tests[level]);
  94                         else
  95                                 s += sprintf(s, "%s ", pm_tests[level]);
  96                 }
  97
  98         if (s != buf)
  99                 /* convert the last space to a newline */
 100                 *(s-1) = '\n';
 101
 102         return (s - buf);
 103 }
 104
 105 static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
 106                                 const char *buf, size_t n)
 107 {
 108         const char * const *s;
 109         int level;
 110         char *p;
 111         int len;
 112         int error = -EINVAL;
 113
 114         p = memchr(buf, '\n', n);
 115         len = p ? p - buf : n;
 116
 117         mutex_lock(&pm_mutex);
 118
 119         level = TEST_FIRST;
 120         for (s = &pm_tests[level]; level <= TEST_MAX; s++, level++)
 121                 if (*s && len == strlen(*s) && !strncmp(buf, *s, len)) {
 122                         pm_test_level = level;
 123                         error = 0;
 124                         break;
 125                 }
 126
 127         mutex_unlock(&pm_mutex);
 128
 129         return error ? error : n;
 130 }
 131
 132 power_attr(pm_test);
 133 #endif /* CONFIG_PM_DEBUG */
 134
 135 #endif /* CONFIG_PM_SLEEP */
 136
 137 struct kobject *power_kobj;
 138
 139 /**
 140  *      state - control system power state.
 141  *
 142  *      show() returns what states are supported, which is hard-coded to
 143  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 144  *      'disk' (Suspend-to-Disk).
 145  *
 146  *      store() accepts one of those strings, translates it into the
 147  *      proper enumerated value, and initiates a suspend transition.
 148  */
 149 static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
 150                           char *buf)
 151 {
 152         char *s = buf;
 153 #ifdef CONFIG_SUSPEND
 154         int i;
 155
 156         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 157                 if (pm_states[i] && valid_state(i))
 158                         s += sprintf(s,"%s ", pm_states[i]);
 159         }
 160 #endif
 161 #ifdef CONFIG_HIBERNATION
 162         s += sprintf(s, "%s\n", "disk");
 163 #else
 164         if (s != buf)
 165                 /* convert the last space to a newline */
 166                 *(s-1) = '\n';
 167 #endif
 168         return (s - buf);
 169 }
 170
 171 static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 172                            const char *buf, size_t n)
 173 {
 174 #ifdef CONFIG_SUSPEND
 175         suspend_state_t state = PM_SUSPEND_STANDBY;
 176         const char * const *s;
 177 #endif
 178         char *p;
 179         int len;
 180         int error = -EINVAL;
 181
 182         p = memchr(buf, '\n', n);
 183         len = p ? p - buf : n;
 184
 185         /* First, check if we are requested to hibernate */
 186         if (len == 4 && !strncmp(buf, "disk", len)) {
 187                 error = hibernate();
 188   goto Exit;
 189         }
 190
 191 #ifdef CONFIG_SUSPEND
 192         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 193                 if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
 194                         break;
 195         }
 196         if (state < PM_SUSPEND_MAX && *s)
 197                 error = enter_state(state);
 198 #endif
 199
 200  Exit:
 201         return error ? error : n;
 202 }
 203
 204 power_attr(state);
 205
 206 #ifdef CONFIG_PM_SLEEP
 207 /*
 208  * The 'wakeup_count' attribute, along with the functions defined in
 209  * drivers/base/power/wakeup.c, provides a means by which wakeup events can be
 210  * handled in a non-racy way.
 211  *
 212  * If a wakeup event occurs when the system is in a sleep state, it simply is
 213  * woken up.  In turn, if an event that would wake the system up from a sleep
 214  * state occurs when it is undergoing a transition to that sleep state, the
 215  * transition should be aborted.  Moreover, if such an event occurs when the
 216  * system is in the working state, an attempt to start a transition to the
 217  * given sleep state should fail during certain period after the detection of
 218  * the event.  Using the 'state' attribute alone is not sufficient to satisfy
 219  * these requirements, because a wakeup event may occur exactly when 'state'
 220  * is being written to and may be delivered to user space right before it is
 221  * frozen, so the event will remain only partially processed until the system is
 222  * woken up by another event.  In particular, it won't cause the transition to
 223  * a sleep state to be aborted.
 224  *
 225  * This difficulty may be overcome if user space uses 'wakeup_count' before
 226  * writing to 'state'.  It first should read from 'wakeup_count' and store
 227  * the read value.  Then, after carrying out its own preparations for the system
 228  * transition to a sleep state, it should write the stored value to
 229  * 'wakeup_count'.  If that fails, at least one wakeup event has occurred since
 230  * 'wakeup_count' was read and 'state' should not be written to.  Otherwise, it
 231  * is allowed to write to 'state', but the transition will be aborted if there
 232  * are any wakeup events detected after 'wakeup_count' was written to.
 233  */
 234
 235 static ssize_t wakeup_count_show(struct kobject *kobj,
 236                                 struct kobj_attribute *attr,
 237                                 char *buf)
 238 {
 239         unsigned int val;
 240
 241         return pm_get_wakeup_count(&val) ? sprintf(buf, "%u\n", val) : -EINTR;
 242 }
 243
 244 static ssize_t wakeup_count_store(struct kobject *kobj,
 245                                 struct kobj_attribute *attr,
 246                                 const char *buf, size_t n)
 247 {
 248         unsigned int val;
 249
 250         if (sscanf(buf, "%u", &val) == 1) {
 251                 if (pm_save_wakeup_count(val))
 252                         return n;
 253         }
 254         return -EINVAL;
 255 }
 256
 257 power_attr(wakeup_count);
 258 #endif /* CONFIG_PM_SLEEP */
 259
 260 #ifdef CONFIG_PM_TRACE
 261 int pm_trace_enabled;
 262
 263 static ssize_t pm_trace_show(struct kobject *kobj, struct kobj_attribute *attr,
 264                              char *buf)
 265 {
 266         return sprintf(buf, "%d\n", pm_trace_enabled);
 267 }
 268
 269 static ssize_t
 270 pm_trace_store(struct kobject *kobj, struct kobj_attribute *attr,
 271                const char *buf, size_t n)
 272 {
 273         int val;
 274
 275         if (sscanf(buf, "%d", &val) == 1) {
 276                 pm_trace_enabled = !!val;
 277                 return n;
 278         }
 279         return -EINVAL;
 280 }
 281
 282 power_attr(pm_trace);
 283
 284 static ssize_t pm_trace_dev_match_show(struct kobject *kobj,
 285                                        struct kobj_attribute *attr,
 286                                        char *buf)
 287 {
 288         return show_trace_dev_match(buf, PAGE_SIZE);
 289 }
 290
 291 static ssize_t
 292 pm_trace_dev_match_store(struct kobject *kobj, struct kobj_attribute *attr,
 293                          const char *buf, size_t n)
 294 {
 295         return -EINVAL;
 296 }
 297
 298 power_attr(pm_trace_dev_match);
 299
 300 #endif /* CONFIG_PM_TRACE */
 301
 302 static struct attribute * g[] = {
 303         &state_attr.attr,
 304 #ifdef CONFIG_PM_TRACE
 305         &pm_trace_attr.attr,
 306         &pm_trace_dev_match_attr.attr,
 307 #endif
 308 #ifdef CONFIG_PM_SLEEP
 309         &pm_async_attr.attr,
 310         &wakeup_count_attr.attr,
 311 #ifdef CONFIG_PM_DEBUG
 312         &pm_test_attr.attr,
 313 #endif
 314 #endif
 315         NULL,
 316 };
 317
 318 static struct attribute_group attr_group = {
 319         .attrs = g,
 320 };
 321
 322 #ifdef CONFIG_PM_RUNTIME
 323 struct workqueue_struct *pm_wq;
 324 EXPORT_SYMBOL_GPL(pm_wq);
 325
 326 static int __init pm_start_workqueue(void)
 327 {
 328         pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0);
 329
 330         return pm_wq ? 0 : -ENOMEM;
 331 }
 332 #else
 333 static inline int pm_start_workqueue(void) { return 0; }
 334 #endif
 335
 336 static int __init pm_init(void)
 337 {
 338         int error = pm_start_workqueue();
 339         if (error)
 340                 return error;
 341         hibernate_image_size_init();
 342         hibernate_reserved_size_init();
 343         power_kobj = kobject_create_and_add("power", NULL);
 344         if (!power_kobj)
 345                 return -ENOMEM;
 346         return sysfs_create_group(power_kobj, &attr_group);
 347 }
 348
 349 core_initcall(pm_init);