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/suspend.h>
  12 #include <linux/kobject.h>
  13 #include <linux/string.h>
  14 #include <linux/delay.h>
  15 #include <linux/errno.h>
  16 #include <linux/init.h>
  17 #include <linux/pm.h>
  18 #include <linux/console.h>
  19 #include <linux/cpu.h>
  20 #include <linux/resume-trace.h>
  21
  22 #include "power.h"
  23
  24 /*This is just an arbitrary number */
  25 #define FREE_PAGE_NUMBER (100)
  26
  27 DECLARE_MUTEX(pm_sem);
  28
  29 struct pm_ops *pm_ops;
  30 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
  31
  32 /**
  33  *      pm_set_ops - Set the global power method table.
  34  *      @ops:   Pointer to ops structure.
  35  */
  36
  37 void pm_set_ops(struct pm_ops * ops)
  38 {
  39         down(&pm_sem);
  40         pm_ops = ops;
  41         up(&pm_sem);
  42 }
  43
  44
  45 /**
  46  *      suspend_prepare - Do prep work before entering low-power state.
  47  *      @state:         State we're entering.
  48  *
  49  *      This is common code that is called for each state that we're
  50  *      entering. Allocate a console, stop all processes, then make sure
  51  *      the platform can enter the requested state.
  52  */
  53
  54 static int suspend_prepare(suspend_state_t state)
  55 {
  56         int error;
  57         unsigned int free_pages;
  58
  59         if (!pm_ops || !pm_ops->enter)
  60                 return -EPERM;
  61
  62         pm_prepare_console();
  63
  64         error = disable_nonboot_cpus();
  65         if (error)
  66                 goto Enable_cpu;
  67
  68         if (freeze_processes()) {
  69                 error = -EAGAIN;
  70                 goto Thaw;
  71         }
  72
  73         if ((free_pages = nr_free_pages()) < FREE_PAGE_NUMBER) {
  74                 pr_debug("PM: free some memory\n");
  75                 shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
  76                 if (nr_free_pages() < FREE_PAGE_NUMBER) {
  77                         error = -ENOMEM;
  78                         printk(KERN_ERR "PM: No enough memory\n");
  79                         goto Thaw;
  80                 }
  81         }
  82
  83         if (pm_ops->prepare) {
  84                 if ((error = pm_ops->prepare(state)))
  85                         goto Thaw;
  86         }
  87
  88         suspend_console();
  89         if ((error = device_suspend(PMSG_SUSPEND))) {
  90                 printk(KERN_ERR "Some devices failed to suspend\n");
  91                 goto Finish;
  92         }
  93         return 0;
  94  Finish:
  95         if (pm_ops->finish)
  96                 pm_ops->finish(state);
  97  Thaw:
  98         thaw_processes();
  99  Enable_cpu:
 100         enable_nonboot_cpus();
 101         pm_restore_console();
 102         return error;
 103 }
 104
 105
 106 int suspend_enter(suspend_state_t state)
 107 {
 108         int error = 0;
 109         unsigned long flags;
 110
 111         local_irq_save(flags);
 112
 113         if ((error = device_power_down(PMSG_SUSPEND))) {
 114                 printk(KERN_ERR "Some devices failed to power down\n");
 115                 goto Done;
 116         }
 117         error = pm_ops->enter(state);
 118         device_power_up();
 119  Done:
 120         local_irq_restore(flags);
 121         return error;
 122 }
 123
 124
 125 /**
 126  *      suspend_finish - Do final work before exiting suspend sequence.
 127  *      @state:         State we're coming out of.
 128  *
 129  *      Call platform code to clean up, restart processes, and free the
 130  *      console that we've allocated. This is not called for suspend-to-disk.
 131  */
 132
 133 static void suspend_finish(suspend_state_t state)
 134 {
 135         device_resume();
 136         resume_console();
 137         thaw_processes();
 138         enable_nonboot_cpus();
 139         if (pm_ops && pm_ops->finish)
 140                 pm_ops->finish(state);
 141         pm_restore_console();
 142 }
 143
 144
 145
 146
 147 static const char * const pm_states[PM_SUSPEND_MAX] = {
 148         [PM_SUSPEND_STANDBY]    = "standby",
 149         [PM_SUSPEND_MEM]        = "mem",
 150 #ifdef CONFIG_SOFTWARE_SUSPEND
 151         [PM_SUSPEND_DISK]       = "disk",
 152 #endif
 153 };
 154
 155 static inline int valid_state(suspend_state_t state)
 156 {
 157         /* Suspend-to-disk does not really need low-level support.
 158          * It can work with reboot if needed. */
 159         if (state == PM_SUSPEND_DISK)
 160                 return 1;
 161
 162         if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
 163                 return 0;
 164         return 1;
 165 }
 166
 167
 168 /**
 169  *      enter_state - Do common work of entering low-power state.
 170  *      @state:         pm_state structure for state we're entering.
 171  *
 172  *      Make sure we're the only ones trying to enter a sleep state. Fail
 173  *      if someone has beat us to it, since we don't want anything weird to
 174  *      happen when we wake up.
 175  *      Then, do the setup for suspend, enter the state, and cleaup (after
 176  *      we've woken up).
 177  */
 178
 179 static int enter_state(suspend_state_t state)
 180 {
 181         int error;
 182
 183         if (!valid_state(state))
 184                 return -ENODEV;
 185         if (down_trylock(&pm_sem))
 186                 return -EBUSY;
 187
 188         if (state == PM_SUSPEND_DISK) {
 189                 error = pm_suspend_disk();
 190                 goto Unlock;
 191         }
 192
 193         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 194         if ((error = suspend_prepare(state)))
 195                 goto Unlock;
 196
 197         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 198         error = suspend_enter(state);
 199
 200         pr_debug("PM: Finishing wakeup.\n");
 201         suspend_finish(state);
 202  Unlock:
 203         up(&pm_sem);
 204         return error;
 205 }
 206
 207 /*
 208  * This is main interface to the outside world. It needs to be
 209  * called from process context.
 210  */
 211 int software_suspend(void)
 212 {
 213         return enter_state(PM_SUSPEND_DISK);
 214 }
 215
 216
 217 /**
 218  *      pm_suspend - Externally visible function for suspending system.
 219  *      @state:         Enumarted value of state to enter.
 220  *
 221  *      Determine whether or not value is within range, get state
 222  *      structure, and enter (above).
 223  */
 224
 225 int pm_suspend(suspend_state_t state)
 226 {
 227         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 228                 return enter_state(state);
 229         return -EINVAL;
 230 }
 231
 232
 233
 234 decl_subsys(power,NULL,NULL);
 235
 236
 237 /**
 238  *      state - control system power state.
 239  *
 240  *      show() returns what states are supported, which is hard-coded to
 241  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 242  *      'disk' (Suspend-to-Disk).
 243  *
 244  *      store() accepts one of those strings, translates it into the
 245  *      proper enumerated value, and initiates a suspend transition.
 246  */
 247
 248 static ssize_t state_show(struct subsystem * subsys, char * buf)
 249 {
 250         int i;
 251         char * s = buf;
 252
 253         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 254                 if (pm_states[i] && valid_state(i))
 255                         s += sprintf(s,"%s ", pm_states[i]);
 256         }
 257         s += sprintf(s,"\n");
 258         return (s - buf);
 259 }
 260
 261 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 262 {
 263         suspend_state_t state = PM_SUSPEND_STANDBY;
 264         const char * const *s;
 265         char *p;
 266         int error;
 267         int len;
 268
 269         p = memchr(buf, '\n', n);
 270         len = p ? p - buf : n;
 271
 272         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 273                 if (*s && !strncmp(buf, *s, len))
 274                         break;
 275         }
 276         if (state < PM_SUSPEND_MAX && *s)
 277                 error = enter_state(state);
 278         else
 279                 error = -EINVAL;
 280         return error ? error : n;
 281 }
 282
 283 power_attr(state);
 284
 285 #ifdef CONFIG_PM_TRACE
 286 int pm_trace_enabled;
 287
 288 static ssize_t pm_trace_show(struct subsystem * subsys, char * buf)
 289 {
 290         return sprintf(buf, "%d\n", pm_trace_enabled);
 291 }
 292
 293 static ssize_t
 294 pm_trace_store(struct subsystem * subsys, const char * buf, size_t n)
 295 {
 296         int val;
 297
 298         if (sscanf(buf, "%d", &val) == 1) {
 299                 pm_trace_enabled = !!val;
 300                 return n;
 301         }
 302         return -EINVAL;
 303 }
 304
 305 power_attr(pm_trace);
 306
 307 static struct attribute * g[] = {
 308         &state_attr.attr,
 309         &pm_trace_attr.attr,
 310         NULL,
 311 };
 312 #else
 313 static struct attribute * g[] = {
 314         &state_attr.attr,
 315         NULL,
 316 };
 317 #endif /* CONFIG_PM_TRACE */
 318
 319 static struct attribute_group attr_group = {
 320         .attrs = g,
 321 };
 322
 323
 324 static int __init pm_init(void)
 325 {
 326         int error = subsystem_register(&power_subsys);
 327         if (!error)
 328                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 329         return error;
 330 }
 331
 332 core_initcall(pm_init);