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/module.h>
  12 #include <linux/suspend.h>
  13 #include <linux/kobject.h>
  14 #include <linux/string.h>
  15 #include <linux/delay.h>
  16 #include <linux/errno.h>
  17 #include <linux/init.h>
  18 #include <linux/pm.h>
  19 #include <linux/console.h>
  20 #include <linux/cpu.h>
  21 #include <linux/resume-trace.h>
  22 #include <linux/freezer.h>
  23 #include <linux/vmstat.h>
  24
  25 #include "power.h"
  26
  27 /*This is just an arbitrary number */
  28 #define FREE_PAGE_NUMBER (100)
  29
  30 DEFINE_MUTEX(pm_mutex);
  31
  32 struct pm_ops *pm_ops;
  33
  34 /**
  35  *      pm_set_ops - Set the global power method table.
  36  *      @ops:   Pointer to ops structure.
  37  */
  38
  39 void pm_set_ops(struct pm_ops * ops)
  40 {
  41         mutex_lock(&pm_mutex);
  42         pm_ops = ops;
  43         mutex_unlock(&pm_mutex);
  44 }
  45
  46 /**
  47  * pm_valid_only_mem - generic memory-only valid callback
  48  *
  49  * pm_ops drivers that implement mem suspend only and only need
  50  * to check for that in their .valid callback can use this instead
  51  * of rolling their own .valid callback.
  52  */
  53 int pm_valid_only_mem(suspend_state_t state)
  54 {
  55         return state == PM_SUSPEND_MEM;
  56 }
  57
  58
  59 static inline void pm_finish(suspend_state_t state)
  60 {
  61         if (pm_ops->finish)
  62                 pm_ops->finish(state);
  63 }
  64
  65 /**
  66  *      suspend_prepare - Do prep work before entering low-power state.
  67  *      @state:         State we're entering.
  68  *
  69  *      This is common code that is called for each state that we're
  70  *      entering. Allocate a console, stop all processes, then make sure
  71  *      the platform can enter the requested state.
  72  */
  73
  74 static int suspend_prepare(suspend_state_t state)
  75 {
  76         int error;
  77         unsigned int free_pages;
  78
  79         if (!pm_ops || !pm_ops->enter)
  80                 return -EPERM;
  81
  82         pm_prepare_console();
  83
  84         if (freeze_processes()) {
  85                 error = -EAGAIN;
  86                 goto Thaw;
  87         }
  88
  89         if ((free_pages = global_page_state(NR_FREE_PAGES))
  90                         < FREE_PAGE_NUMBER) {
  91                 pr_debug("PM: free some memory\n");
  92                 shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
  93                 if (nr_free_pages() < FREE_PAGE_NUMBER) {
  94                         error = -ENOMEM;
  95                         printk(KERN_ERR "PM: No enough memory\n");
  96                         goto Thaw;
  97                 }
  98         }
  99
 100         suspend_console();
 101         error = device_suspend(PMSG_SUSPEND);
 102         if (error) {
 103                 printk(KERN_ERR "Some devices failed to suspend\n");
 104                 goto Resume_console;
 105         }
 106         if (pm_ops->prepare) {
 107                 if ((error = pm_ops->prepare(state)))
 108                         goto Resume_devices;
 109         }
 110
 111         error = disable_nonboot_cpus();
 112         if (!error)
 113                 return 0;
 114
 115         enable_nonboot_cpus();
 116         pm_finish(state);
 117  Resume_devices:
 118         device_resume();
 119  Resume_console:
 120         resume_console();
 121  Thaw:
 122         thaw_processes();
 123         pm_restore_console();
 124         return error;
 125 }
 126
 127 /* default implementation */
 128 void __attribute__ ((weak)) arch_suspend_disable_irqs(void)
 129 {
 130         local_irq_disable();
 131 }
 132
 133 /* default implementation */
 134 void __attribute__ ((weak)) arch_suspend_enable_irqs(void)
 135 {
 136         local_irq_enable();
 137 }
 138
 139 int suspend_enter(suspend_state_t state)
 140 {
 141         int error = 0;
 142
 143         arch_suspend_disable_irqs();
 144         BUG_ON(!irqs_disabled());
 145
 146         if ((error = device_power_down(PMSG_SUSPEND))) {
 147                 printk(KERN_ERR "Some devices failed to power down\n");
 148                 goto Done;
 149         }
 150         error = pm_ops->enter(state);
 151         device_power_up();
 152  Done:
 153         arch_suspend_enable_irqs();
 154         BUG_ON(irqs_disabled());
 155         return error;
 156 }
 157
 158
 159 /**
 160  *      suspend_finish - Do final work before exiting suspend sequence.
 161  *      @state:         State we're coming out of.
 162  *
 163  *      Call platform code to clean up, restart processes, and free the
 164  *      console that we've allocated. This is not called for suspend-to-disk.
 165  */
 166
 167 static void suspend_finish(suspend_state_t state)
 168 {
 169         enable_nonboot_cpus();
 170         pm_finish(state);
 171         device_resume();
 172         resume_console();
 173         thaw_processes();
 174         pm_restore_console();
 175 }
 176
 177
 178
 179
 180 static const char * const pm_states[PM_SUSPEND_MAX] = {
 181         [PM_SUSPEND_STANDBY]    = "standby",
 182         [PM_SUSPEND_MEM]        = "mem",
 183 };
 184
 185 static inline int valid_state(suspend_state_t state)
 186 {
 187         /* All states need lowlevel support and need to be valid
 188          * to the lowlevel implementation, no valid callback
 189          * implies that none are valid. */
 190         if (!pm_ops || !pm_ops->valid || !pm_ops->valid(state))
 191                 return 0;
 192         return 1;
 193 }
 194
 195
 196 /**
 197  *      enter_state - Do common work of entering low-power state.
 198  *      @state:         pm_state structure for state we're entering.
 199  *
 200  *      Make sure we're the only ones trying to enter a sleep state. Fail
 201  *      if someone has beat us to it, since we don't want anything weird to
 202  *      happen when we wake up.
 203  *      Then, do the setup for suspend, enter the state, and cleaup (after
 204  *      we've woken up).
 205  */
 206
 207 static int enter_state(suspend_state_t state)
 208 {
 209         int error;
 210
 211         if (!valid_state(state))
 212                 return -ENODEV;
 213         if (!mutex_trylock(&pm_mutex))
 214                 return -EBUSY;
 215
 216         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 217         if ((error = suspend_prepare(state)))
 218                 goto Unlock;
 219
 220         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 221         error = suspend_enter(state);
 222
 223         pr_debug("PM: Finishing wakeup.\n");
 224         suspend_finish(state);
 225  Unlock:
 226         mutex_unlock(&pm_mutex);
 227         return error;
 228 }
 229
 230
 231 /**
 232  *      pm_suspend - Externally visible function for suspending system.
 233  *      @state:         Enumerated value of state to enter.
 234  *
 235  *      Determine whether or not value is within range, get state
 236  *      structure, and enter (above).
 237  */
 238
 239 int pm_suspend(suspend_state_t state)
 240 {
 241         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 242                 return enter_state(state);
 243         return -EINVAL;
 244 }
 245
 246 EXPORT_SYMBOL(pm_suspend);
 247
 248 decl_subsys(power,NULL,NULL);
 249
 250
 251 /**
 252  *      state - control system power state.
 253  *
 254  *      show() returns what states are supported, which is hard-coded to
 255  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 256  *      'disk' (Suspend-to-Disk).
 257  *
 258  *      store() accepts one of those strings, translates it into the
 259  *      proper enumerated value, and initiates a suspend transition.
 260  */
 261
 262 static ssize_t state_show(struct kset *kset, char *buf)
 263 {
 264         int i;
 265         char * s = buf;
 266
 267         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 268                 if (pm_states[i] && valid_state(i))
 269                         s += sprintf(s,"%s ", pm_states[i]);
 270         }
 271 #ifdef CONFIG_SOFTWARE_SUSPEND
 272         s += sprintf(s, "%s\n", "disk");
 273 #else
 274         if (s != buf)
 275                 /* convert the last space to a newline */
 276                 *(s-1) = '\n';
 277 #endif
 278         return (s - buf);
 279 }
 280
 281 static ssize_t state_store(struct kset *kset, const char *buf, size_t n)
 282 {
 283         suspend_state_t state = PM_SUSPEND_STANDBY;
 284         const char * const *s;
 285         char *p;
 286         int error;
 287         int len;
 288
 289         p = memchr(buf, '\n', n);
 290         len = p ? p - buf : n;
 291
 292         /* First, check if we are requested to hibernate */
 293         if (len == 4 && !strncmp(buf, "disk", len)) {
 294                 error = hibernate();
 295                 return error ? error : n;
 296         }
 297
 298         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 299                 if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
 300                         break;
 301         }
 302         if (state < PM_SUSPEND_MAX && *s)
 303                 error = enter_state(state);
 304         else
 305                 error = -EINVAL;
 306         return error ? error : n;
 307 }
 308
 309 power_attr(state);
 310
 311 #ifdef CONFIG_PM_TRACE
 312 int pm_trace_enabled;
 313
 314 static ssize_t pm_trace_show(struct kset *kset, char *buf)
 315 {
 316         return sprintf(buf, "%d\n", pm_trace_enabled);
 317 }
 318
 319 static ssize_t
 320 pm_trace_store(struct kset *kset, const char *buf, size_t n)
 321 {
 322         int val;
 323
 324         if (sscanf(buf, "%d", &val) == 1) {
 325                 pm_trace_enabled = !!val;
 326                 return n;
 327         }
 328         return -EINVAL;
 329 }
 330
 331 power_attr(pm_trace);
 332
 333 static struct attribute * g[] = {
 334         &state_attr.attr,
 335         &pm_trace_attr.attr,
 336         NULL,
 337 };
 338 #else
 339 static struct attribute * g[] = {
 340         &state_attr.attr,
 341         NULL,
 342 };
 343 #endif /* CONFIG_PM_TRACE */
 344
 345 static struct attribute_group attr_group = {
 346         .attrs = g,
 347 };
 348
 349
 350 static int __init pm_init(void)
 351 {
 352         int error = subsystem_register(&power_subsys);
 353         if (!error)
 354                 error = sysfs_create_group(&power_subsys.kobj,&attr_group);
 355         return error;
 356 }
 357
 358 core_initcall(pm_init);