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