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
  24 #include "power.h"
  25
  26 /*This is just an arbitrary number */
  27 #define FREE_PAGE_NUMBER (100)
  28
  29 DEFINE_MUTEX(pm_mutex);
  30
  31 struct pm_ops *pm_ops;
  32 suspend_disk_method_t pm_disk_mode = PM_DISK_PLATFORM;
  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 /**
  48  *      suspend_prepare - Do prep work before entering low-power state.
  49  *      @state:         State we're entering.
  50  *
  51  *      This is common code that is called for each state that we're
  52  *      entering. Allocate a console, stop all processes, then make sure
  53  *      the platform can enter the requested state.
  54  */
  55
  56 static int suspend_prepare(suspend_state_t state)
  57 {
  58         int error;
  59         unsigned int free_pages;
  60
  61         if (!pm_ops || !pm_ops->enter)
  62                 return -EPERM;
  63
  64         pm_prepare_console();
  65
  66         error = disable_nonboot_cpus();
  67         if (error)
  68                 goto Enable_cpu;
  69
  70         if (freeze_processes()) {
  71                 error = -EAGAIN;
  72                 goto Thaw;
  73         }
  74
  75         if ((free_pages = nr_free_pages()) < FREE_PAGE_NUMBER) {
  76                 pr_debug("PM: free some memory\n");
  77                 shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
  78                 if (nr_free_pages() < FREE_PAGE_NUMBER) {
  79                         error = -ENOMEM;
  80                         printk(KERN_ERR "PM: No enough memory\n");
  81                         goto Thaw;
  82                 }
  83         }
  84
  85         if (pm_ops->prepare) {
  86                 if ((error = pm_ops->prepare(state)))
  87                         goto Thaw;
  88         }
  89
  90         suspend_console();
  91         if ((error = device_suspend(PMSG_SUSPEND))) {
  92                 printk(KERN_ERR "Some devices failed to suspend\n");
  93                 goto Finish;
  94         }
  95         return 0;
  96  Finish:
  97         if (pm_ops->finish)
  98                 pm_ops->finish(state);
  99  Thaw:
 100         thaw_processes();
 101  Enable_cpu:
 102         enable_nonboot_cpus();
 103         pm_restore_console();
 104         return error;
 105 }
 106
 107
 108 int suspend_enter(suspend_state_t state)
 109 {
 110         int error = 0;
 111         unsigned long flags;
 112
 113         local_irq_save(flags);
 114
 115         if ((error = device_power_down(PMSG_SUSPEND))) {
 116                 printk(KERN_ERR "Some devices failed to power down\n");
 117                 goto Done;
 118         }
 119         error = pm_ops->enter(state);
 120         device_power_up();
 121  Done:
 122         local_irq_restore(flags);
 123         return error;
 124 }
 125
 126
 127 /**
 128  *      suspend_finish - Do final work before exiting suspend sequence.
 129  *      @state:         State we're coming out of.
 130  *
 131  *      Call platform code to clean up, restart processes, and free the
 132  *      console that we've allocated. This is not called for suspend-to-disk.
 133  */
 134
 135 static void suspend_finish(suspend_state_t state)
 136 {
 137         device_resume();
 138         resume_console();
 139         thaw_processes();
 140         enable_nonboot_cpus();
 141         if (pm_ops && pm_ops->finish)
 142                 pm_ops->finish(state);
 143         pm_restore_console();
 144 }
 145
 146
 147
 148
 149 static const char * const pm_states[PM_SUSPEND_MAX] = {
 150         [PM_SUSPEND_STANDBY]    = "standby",
 151         [PM_SUSPEND_MEM]        = "mem",
 152 #ifdef CONFIG_SOFTWARE_SUSPEND
 153         [PM_SUSPEND_DISK]       = "disk",
 154 #endif
 155 };
 156
 157 static inline int valid_state(suspend_state_t state)
 158 {
 159         /* Suspend-to-disk does not really need low-level support.
 160          * It can work with reboot if needed. */
 161         if (state == PM_SUSPEND_DISK)
 162                 return 1;
 163
 164         if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
 165                 return 0;
 166         return 1;
 167 }
 168
 169
 170 /**
 171  *      enter_state - Do common work of entering low-power state.
 172  *      @state:         pm_state structure for state we're entering.
 173  *
 174  *      Make sure we're the only ones trying to enter a sleep state. Fail
 175  *      if someone has beat us to it, since we don't want anything weird to
 176  *      happen when we wake up.
 177  *      Then, do the setup for suspend, enter the state, and cleaup (after
 178  *      we've woken up).
 179  */
 180
 181 static int enter_state(suspend_state_t state)
 182 {
 183         int error;
 184
 185         if (!valid_state(state))
 186                 return -ENODEV;
 187         if (!mutex_trylock(&pm_mutex))
 188                 return -EBUSY;
 189
 190         if (state == PM_SUSPEND_DISK) {
 191                 error = pm_suspend_disk();
 192                 goto Unlock;
 193         }
 194
 195         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 196         if ((error = suspend_prepare(state)))
 197                 goto Unlock;
 198
 199         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 200         error = suspend_enter(state);
 201
 202         pr_debug("PM: Finishing wakeup.\n");
 203         suspend_finish(state);
 204  Unlock:
 205         mutex_unlock(&pm_mutex);
 206         return error;
 207 }
 208
 209 /*
 210  * This is main interface to the outside world. It needs to be
 211  * called from process context.
 212  */
 213 int software_suspend(void)
 214 {
 215         return enter_state(PM_SUSPEND_DISK);
 216 }
 217
 218
 219 /**
 220  *      pm_suspend - Externally visible function for suspending system.
 221  *      @state:         Enumarted value of state to enter.
 222  *
 223  *      Determine whether or not value is within range, get state
 224  *      structure, and enter (above).
 225  */
 226
 227 int pm_suspend(suspend_state_t state)
 228 {
 229         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 230                 return enter_state(state);
 231         return -EINVAL;
 232 }
 233
 234 EXPORT_SYMBOL(pm_suspend);
 235
 236 decl_subsys(power,NULL,NULL);
 237
 238
 239 /**
 240  *      state - control system power state.
 241  *
 242  *      show() returns what states are supported, which is hard-coded to
 243  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 244  *      'disk' (Suspend-to-Disk).
 245  *
 246  *      store() accepts one of those strings, translates it into the
 247  *      proper enumerated value, and initiates a suspend transition.
 248  */
 249
 250 static ssize_t state_show(struct subsystem * subsys, char * buf)
 251 {
 252         int i;
 253         char * s = buf;
 254
 255         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 256                 if (pm_states[i] && valid_state(i))
 257                         s += sprintf(s,"%s ", pm_states[i]);
 258         }
 259         s += sprintf(s,"\n");
 260         return (s - buf);
 261 }
 262
 263 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 264 {
 265         suspend_state_t state = PM_SUSPEND_STANDBY;
 266         const char * const *s;
 267         char *p;
 268         int error;
 269         int len;
 270
 271         p = memchr(buf, '\n', n);
 272         len = p ? p - buf : n;
 273
 274         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 275                 if (*s && !strncmp(buf, *s, len))
 276                         break;
 277         }
 278         if (state < PM_SUSPEND_MAX && *s)
 279                 error = enter_state(state);
 280         else
 281                 error = -EINVAL;
 282         return error ? error : n;
 283 }
 284
 285 power_attr(state);
 286
 287 #ifdef CONFIG_PM_TRACE
 288 int pm_trace_enabled;
 289
 290 static ssize_t pm_trace_show(struct subsystem * subsys, char * buf)
 291 {
 292         return sprintf(buf, "%d\n", pm_trace_enabled);
 293 }
 294
 295 static ssize_t
 296 pm_trace_store(struct subsystem * subsys, const char * buf, size_t n)
 297 {
 298         int val;
 299
 300         if (sscanf(buf, "%d", &val) == 1) {
 301                 pm_trace_enabled = !!val;
 302                 return n;
 303         }
 304         return -EINVAL;
 305 }
 306
 307 power_attr(pm_trace);
 308
 309 static struct attribute * g[] = {
 310         &state_attr.attr,
 311         &pm_trace_attr.attr,
 312         NULL,
 313 };
 314 #else
 315 static struct attribute * g[] = {
 316         &state_attr.attr,
 317         NULL,
 318 };
 319 #endif /* CONFIG_PM_TRACE */
 320
 321 static struct attribute_group attr_group = {
 322         .attrs = g,
 323 };
 324
 325
 326 static int __init pm_init(void)
 327 {
 328         int error = subsystem_register(&power_subsys);
 329         if (!error)
 330                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 331         return error;
 332 }
 333
 334 core_initcall(pm_init);