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 = NULL;
  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         if (freeze_processes()) {
  63                 error = -EAGAIN;
  64                 goto Thaw;
  65         }
  66
  67         if ((free_pages = nr_free_pages()) < FREE_PAGE_NUMBER) {
  68                 pr_debug("PM: free some memory\n");
  69                 shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
  70                 if (nr_free_pages() < FREE_PAGE_NUMBER) {
  71                         error = -ENOMEM;
  72                         printk(KERN_ERR "PM: No enough memory\n");
  73                         goto Thaw;
  74                 }
  75         }
  76
  77         if (pm_ops->prepare) {
  78                 if ((error = pm_ops->prepare(state)))
  79                         goto Thaw;
  80         }
  81
  82         if ((error = device_suspend(PMSG_SUSPEND))) {
  83                 printk(KERN_ERR "Some devices failed to suspend\n");
  84                 goto Finish;
  85         }
  86         return 0;
  87  Finish:
  88         if (pm_ops->finish)
  89                 pm_ops->finish(state);
  90  Thaw:
  91         thaw_processes();
  92         pm_restore_console();
  93         return error;
  94 }
  95
  96
  97 static int suspend_enter(suspend_state_t state)
  98 {
  99         int error = 0;
 100         unsigned long flags;
 101
 102         local_irq_save(flags);
 103
 104         if ((error = device_power_down(PMSG_SUSPEND))) {
 105                 printk(KERN_ERR "Some devices failed to power down\n");
 106                 goto Done;
 107         }
 108         error = pm_ops->enter(state);
 109         device_power_up();
 110  Done:
 111         local_irq_restore(flags);
 112         return error;
 113 }
 114
 115
 116 /**
 117  *      suspend_finish - Do final work before exiting suspend sequence.
 118  *      @state:         State we're coming out of.
 119  *
 120  *      Call platform code to clean up, restart processes, and free the
 121  *      console that we've allocated. This is not called for suspend-to-disk.
 122  */
 123
 124 static void suspend_finish(suspend_state_t state)
 125 {
 126         device_resume();
 127         if (pm_ops && pm_ops->finish)
 128                 pm_ops->finish(state);
 129         thaw_processes();
 130         pm_restore_console();
 131 }
 132
 133
 134
 135
 136 static char * pm_states[] = {
 137         [PM_SUSPEND_STANDBY]    = "standby",
 138         [PM_SUSPEND_MEM]        = "mem",
 139         [PM_SUSPEND_DISK]       = "disk",
 140         NULL,
 141 };
 142
 143
 144 /**
 145  *      enter_state - Do common work of entering low-power state.
 146  *      @state:         pm_state structure for state we're entering.
 147  *
 148  *      Make sure we're the only ones trying to enter a sleep state. Fail
 149  *      if someone has beat us to it, since we don't want anything weird to
 150  *      happen when we wake up.
 151  *      Then, do the setup for suspend, enter the state, and cleaup (after
 152  *      we've woken up).
 153  */
 154
 155 static int enter_state(suspend_state_t state)
 156 {
 157         int error;
 158
 159         if (down_trylock(&pm_sem))
 160                 return -EBUSY;
 161
 162         if (state == PM_SUSPEND_DISK) {
 163                 error = pm_suspend_disk();
 164                 goto Unlock;
 165         }
 166
 167         /* Suspend is hard to get right on SMP. */
 168         if (num_online_cpus() != 1) {
 169                 error = -EPERM;
 170                 goto Unlock;
 171         }
 172
 173         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 174         if ((error = suspend_prepare(state)))
 175                 goto Unlock;
 176
 177         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 178         error = suspend_enter(state);
 179
 180         pr_debug("PM: Finishing wakeup.\n");
 181         suspend_finish(state);
 182  Unlock:
 183         up(&pm_sem);
 184         return error;
 185 }
 186
 187 /*
 188  * This is main interface to the outside world. It needs to be
 189  * called from process context.
 190  */
 191 int software_suspend(void)
 192 {
 193         return enter_state(PM_SUSPEND_DISK);
 194 }
 195
 196
 197 /**
 198  *      pm_suspend - Externally visible function for suspending system.
 199  *      @state:         Enumarted value of state to enter.
 200  *
 201  *      Determine whether or not value is within range, get state
 202  *      structure, and enter (above).
 203  */
 204
 205 int pm_suspend(suspend_state_t state)
 206 {
 207         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 208                 return enter_state(state);
 209         return -EINVAL;
 210 }
 211
 212
 213
 214 decl_subsys(power,NULL,NULL);
 215
 216
 217 /**
 218  *      state - control system power state.
 219  *
 220  *      show() returns what states are supported, which is hard-coded to
 221  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 222  *      'disk' (Suspend-to-Disk).
 223  *
 224  *      store() accepts one of those strings, translates it into the
 225  *      proper enumerated value, and initiates a suspend transition.
 226  */
 227
 228 static ssize_t state_show(struct subsystem * subsys, char * buf)
 229 {
 230         int i;
 231         char * s = buf;
 232
 233         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 234                 if (pm_states[i])
 235                         s += sprintf(s,"%s ",pm_states[i]);
 236         }
 237         s += sprintf(s,"\n");
 238         return (s - buf);
 239 }
 240
 241 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 242 {
 243         suspend_state_t state = PM_SUSPEND_STANDBY;
 244         char ** s;
 245         char *p;
 246         int error;
 247         int len;
 248
 249         p = memchr(buf, '\n', n);
 250         len = p ? p - buf : n;
 251
 252         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 253                 if (*s && !strncmp(buf, *s, len))
 254                         break;
 255         }
 256         if (*s)
 257                 error = enter_state(state);
 258         else
 259                 error = -EINVAL;
 260         return error ? error : n;
 261 }
 262
 263 power_attr(state);
 264
 265 static struct attribute * g[] = {
 266         &state_attr.attr,
 267         NULL,
 268 };
 269
 270 static struct attribute_group attr_group = {
 271         .attrs = g,
 272 };
 273
 274
 275 static int __init pm_init(void)
 276 {
 277         int error = subsystem_register(&power_subsys);
 278         if (!error)
 279                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 280         return error;
 281 }
 282
 283 core_initcall(pm_init);