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 DECLARE_MUTEX(pm_sem);
  23
  24 struct pm_ops * pm_ops = NULL;
  25 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
  26
  27 /**
  28  *      pm_set_ops - Set the global power method table.
  29  *      @ops:   Pointer to ops structure.
  30  */
  31
  32 void pm_set_ops(struct pm_ops * ops)
  33 {
  34         down(&pm_sem);
  35         pm_ops = ops;
  36         up(&pm_sem);
  37 }
  38
  39
  40 /**
  41  *      suspend_prepare - Do prep work before entering low-power state.
  42  *      @state:         State we're entering.
  43  *
  44  *      This is common code that is called for each state that we're
  45  *      entering. Allocate a console, stop all processes, then make sure
  46  *      the platform can enter the requested state.
  47  */
  48
  49 static int suspend_prepare(suspend_state_t state)
  50 {
  51         int error = 0;
  52
  53         if (!pm_ops || !pm_ops->enter)
  54                 return -EPERM;
  55
  56         pm_prepare_console();
  57
  58         if (freeze_processes()) {
  59                 error = -EAGAIN;
  60                 goto Thaw;
  61         }
  62
  63         if (pm_ops->prepare) {
  64                 if ((error = pm_ops->prepare(state)))
  65                         goto Thaw;
  66         }
  67
  68         if ((error = device_suspend(PMSG_SUSPEND))) {
  69                 printk(KERN_ERR "Some devices failed to suspend\n");
  70                 goto Finish;
  71         }
  72         return 0;
  73  Finish:
  74         if (pm_ops->finish)
  75                 pm_ops->finish(state);
  76  Thaw:
  77         thaw_processes();
  78         pm_restore_console();
  79         return error;
  80 }
  81
  82
  83 static int suspend_enter(suspend_state_t state)
  84 {
  85         int error = 0;
  86         unsigned long flags;
  87
  88         local_irq_save(flags);
  89
  90         if ((error = device_power_down(PMSG_SUSPEND))) {
  91                 printk(KERN_ERR "Some devices failed to power down\n");
  92                 goto Done;
  93         }
  94         error = pm_ops->enter(state);
  95         device_power_up();
  96  Done:
  97         local_irq_restore(flags);
  98         return error;
  99 }
 100
 101
 102 /**
 103  *      suspend_finish - Do final work before exiting suspend sequence.
 104  *      @state:         State we're coming out of.
 105  *
 106  *      Call platform code to clean up, restart processes, and free the
 107  *      console that we've allocated. This is not called for suspend-to-disk.
 108  */
 109
 110 static void suspend_finish(suspend_state_t state)
 111 {
 112         device_resume();
 113         if (pm_ops && pm_ops->finish)
 114                 pm_ops->finish(state);
 115         thaw_processes();
 116         pm_restore_console();
 117 }
 118
 119
 120
 121
 122 static char * pm_states[] = {
 123         [PM_SUSPEND_STANDBY]    = "standby",
 124         [PM_SUSPEND_MEM]        = "mem",
 125         [PM_SUSPEND_DISK]       = "disk",
 126         NULL,
 127 };
 128
 129
 130 /**
 131  *      enter_state - Do common work of entering low-power state.
 132  *      @state:         pm_state structure for state we're entering.
 133  *
 134  *      Make sure we're the only ones trying to enter a sleep state. Fail
 135  *      if someone has beat us to it, since we don't want anything weird to
 136  *      happen when we wake up.
 137  *      Then, do the setup for suspend, enter the state, and cleaup (after
 138  *      we've woken up).
 139  */
 140
 141 static int enter_state(suspend_state_t state)
 142 {
 143         int error;
 144
 145         if (down_trylock(&pm_sem))
 146                 return -EBUSY;
 147
 148         if (state == PM_SUSPEND_DISK) {
 149                 error = pm_suspend_disk();
 150                 goto Unlock;
 151         }
 152
 153         /* Suspend is hard to get right on SMP. */
 154         if (num_online_cpus() != 1) {
 155                 error = -EPERM;
 156                 goto Unlock;
 157         }
 158
 159         pr_debug("PM: Preparing system for suspend\n");
 160         if ((error = suspend_prepare(state)))
 161                 goto Unlock;
 162
 163         pr_debug("PM: Entering state.\n");
 164         error = suspend_enter(state);
 165
 166         pr_debug("PM: Finishing up.\n");
 167         suspend_finish(state);
 168  Unlock:
 169         up(&pm_sem);
 170         return error;
 171 }
 172
 173 /*
 174  * This is main interface to the outside world. It needs to be
 175  * called from process context.
 176  */
 177 int software_suspend(void)
 178 {
 179         return enter_state(PM_SUSPEND_DISK);
 180 }
 181
 182
 183 /**
 184  *      pm_suspend - Externally visible function for suspending system.
 185  *      @state:         Enumarted value of state to enter.
 186  *
 187  *      Determine whether or not value is within range, get state
 188  *      structure, and enter (above).
 189  */
 190
 191 int pm_suspend(suspend_state_t state)
 192 {
 193         if (state > PM_SUSPEND_ON && state < PM_SUSPEND_MAX)
 194                 return enter_state(state);
 195         return -EINVAL;
 196 }
 197
 198
 199
 200 decl_subsys(power,NULL,NULL);
 201
 202
 203 /**
 204  *      state - control system power state.
 205  *
 206  *      show() returns what states are supported, which is hard-coded to
 207  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 208  *      'disk' (Suspend-to-Disk).
 209  *
 210  *      store() accepts one of those strings, translates it into the
 211  *      proper enumerated value, and initiates a suspend transition.
 212  */
 213
 214 static ssize_t state_show(struct subsystem * subsys, char * buf)
 215 {
 216         int i;
 217         char * s = buf;
 218
 219         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 220                 if (pm_states[i])
 221                         s += sprintf(s,"%s ",pm_states[i]);
 222         }
 223         s += sprintf(s,"\n");
 224         return (s - buf);
 225 }
 226
 227 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 228 {
 229         suspend_state_t state = PM_SUSPEND_STANDBY;
 230         char ** s;
 231         char *p;
 232         int error;
 233         int len;
 234
 235         p = memchr(buf, '\n', n);
 236         len = p ? p - buf : n;
 237
 238         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 239                 if (*s && !strncmp(buf, *s, len))
 240                         break;
 241         }
 242         if (*s)
 243                 error = enter_state(state);
 244         else
 245                 error = -EINVAL;
 246         return error ? error : n;
 247 }
 248
 249 power_attr(state);
 250
 251 static struct attribute * g[] = {
 252         &state_attr.attr,
 253         NULL,
 254 };
 255
 256 static struct attribute_group attr_group = {
 257         .attrs = g,
 258 };
 259
 260
 261 static int __init pm_init(void)
 262 {
 263         int error = subsystem_register(&power_subsys);
 264         if (!error)
 265                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 266         return error;
 267 }
 268
 269 core_initcall(pm_init);