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
  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         suspend_console();
  90         if ((error = device_suspend(PMSG_SUSPEND))) {
  91                 printk(KERN_ERR "Some devices failed to suspend\n");
  92                 goto Finish;
  93         }
  94         return 0;
  95  Finish:
  96         if (pm_ops->finish)
  97                 pm_ops->finish(state);
  98  Thaw:
  99         thaw_processes();
 100  Enable_cpu:
 101         enable_nonboot_cpus();
 102         pm_restore_console();
 103         return error;
 104 }
 105
 106
 107 int suspend_enter(suspend_state_t state)
 108 {
 109         int error = 0;
 110         unsigned long flags;
 111
 112         local_irq_save(flags);
 113
 114         if ((error = device_power_down(PMSG_SUSPEND))) {
 115                 printk(KERN_ERR "Some devices failed to power down\n");
 116                 goto Done;
 117         }
 118         error = pm_ops->enter(state);
 119         device_power_up();
 120  Done:
 121         local_irq_restore(flags);
 122         return error;
 123 }
 124
 125
 126 /**
 127  *      suspend_finish - Do final work before exiting suspend sequence.
 128  *      @state:         State we're coming out of.
 129  *
 130  *      Call platform code to clean up, restart processes, and free the
 131  *      console that we've allocated. This is not called for suspend-to-disk.
 132  */
 133
 134 static void suspend_finish(suspend_state_t state)
 135 {
 136         device_resume();
 137         resume_console();
 138         thaw_processes();
 139         enable_nonboot_cpus();
 140         if (pm_ops && pm_ops->finish)
 141                 pm_ops->finish(state);
 142         pm_restore_console();
 143 }
 144
 145
 146
 147
 148 static const char * const pm_states[PM_SUSPEND_MAX] = {
 149         [PM_SUSPEND_STANDBY]    = "standby",
 150         [PM_SUSPEND_MEM]        = "mem",
 151 #ifdef CONFIG_SOFTWARE_SUSPEND
 152         [PM_SUSPEND_DISK]       = "disk",
 153 #endif
 154 };
 155
 156 static inline int valid_state(suspend_state_t state)
 157 {
 158         /* Suspend-to-disk does not really need low-level support.
 159          * It can work with reboot if needed. */
 160         if (state == PM_SUSPEND_DISK)
 161                 return 1;
 162
 163         if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
 164                 return 0;
 165         return 1;
 166 }
 167
 168
 169 /**
 170  *      enter_state - Do common work of entering low-power state.
 171  *      @state:         pm_state structure for state we're entering.
 172  *
 173  *      Make sure we're the only ones trying to enter a sleep state. Fail
 174  *      if someone has beat us to it, since we don't want anything weird to
 175  *      happen when we wake up.
 176  *      Then, do the setup for suspend, enter the state, and cleaup (after
 177  *      we've woken up).
 178  */
 179
 180 static int enter_state(suspend_state_t state)
 181 {
 182         int error;
 183
 184         if (!valid_state(state))
 185                 return -ENODEV;
 186         if (down_trylock(&pm_sem))
 187                 return -EBUSY;
 188
 189         if (state == PM_SUSPEND_DISK) {
 190                 error = pm_suspend_disk();
 191                 goto Unlock;
 192         }
 193
 194         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 195         if ((error = suspend_prepare(state)))
 196                 goto Unlock;
 197
 198         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 199         error = suspend_enter(state);
 200
 201         pr_debug("PM: Finishing wakeup.\n");
 202         suspend_finish(state);
 203  Unlock:
 204         up(&pm_sem);
 205         return error;
 206 }
 207
 208 /*
 209  * This is main interface to the outside world. It needs to be
 210  * called from process context.
 211  */
 212 int software_suspend(void)
 213 {
 214         return enter_state(PM_SUSPEND_DISK);
 215 }
 216
 217
 218 /**
 219  *      pm_suspend - Externally visible function for suspending system.
 220  *      @state:         Enumarted value of state to enter.
 221  *
 222  *      Determine whether or not value is within range, get state
 223  *      structure, and enter (above).
 224  */
 225
 226 int pm_suspend(suspend_state_t state)
 227 {
 228         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 229                 return enter_state(state);
 230         return -EINVAL;
 231 }
 232
 233
 234
 235 decl_subsys(power,NULL,NULL);
 236
 237
 238 /**
 239  *      state - control system power state.
 240  *
 241  *      show() returns what states are supported, which is hard-coded to
 242  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 243  *      'disk' (Suspend-to-Disk).
 244  *
 245  *      store() accepts one of those strings, translates it into the
 246  *      proper enumerated value, and initiates a suspend transition.
 247  */
 248
 249 static ssize_t state_show(struct subsystem * subsys, char * buf)
 250 {
 251         int i;
 252         char * s = buf;
 253
 254         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 255                 if (pm_states[i] && valid_state(i))
 256                         s += sprintf(s,"%s ", pm_states[i]);
 257         }
 258         s += sprintf(s,"\n");
 259         return (s - buf);
 260 }
 261
 262 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 263 {
 264         suspend_state_t state = PM_SUSPEND_STANDBY;
 265         const char * const *s;
 266         char *p;
 267         int error;
 268         int len;
 269
 270         p = memchr(buf, '\n', n);
 271         len = p ? p - buf : n;
 272
 273         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 274                 if (*s && !strncmp(buf, *s, len))
 275                         break;
 276         }
 277         if (state < PM_SUSPEND_MAX && *s)
 278                 error = enter_state(state);
 279         else
 280                 error = -EINVAL;
 281         return error ? error : n;
 282 }
 283
 284 power_attr(state);
 285
 286 static struct attribute * g[] = {
 287         &state_attr.attr,
 288         NULL,
 289 };
 290
 291 static struct attribute_group attr_group = {
 292         .attrs = g,
 293 };
 294
 295
 296 static int __init pm_init(void)
 297 {
 298         int error = subsystem_register(&power_subsys);
 299         if (!error)
 300                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 301         return error;
 302 }
 303
 304 core_initcall(pm_init);