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         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[] = {
 147         [PM_SUSPEND_STANDBY]    = "standby",
 148         [PM_SUSPEND_MEM]        = "mem",
 149         [PM_SUSPEND_DISK]       = "disk",
 150         NULL,
 151 };
 152
 153
 154 /**
 155  *      enter_state - Do common work of entering low-power state.
 156  *      @state:         pm_state structure for state we're entering.
 157  *
 158  *      Make sure we're the only ones trying to enter a sleep state. Fail
 159  *      if someone has beat us to it, since we don't want anything weird to
 160  *      happen when we wake up.
 161  *      Then, do the setup for suspend, enter the state, and cleaup (after
 162  *      we've woken up).
 163  */
 164
 165 static int enter_state(suspend_state_t state)
 166 {
 167         int error;
 168
 169         if (down_trylock(&pm_sem))
 170                 return -EBUSY;
 171
 172         if (state == PM_SUSPEND_DISK) {
 173                 error = pm_suspend_disk();
 174                 goto Unlock;
 175         }
 176
 177         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 178         if ((error = suspend_prepare(state)))
 179                 goto Unlock;
 180
 181         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 182         error = suspend_enter(state);
 183
 184         pr_debug("PM: Finishing wakeup.\n");
 185         suspend_finish(state);
 186  Unlock:
 187         up(&pm_sem);
 188         return error;
 189 }
 190
 191 /*
 192  * This is main interface to the outside world. It needs to be
 193  * called from process context.
 194  */
 195 int software_suspend(void)
 196 {
 197         return enter_state(PM_SUSPEND_DISK);
 198 }
 199
 200
 201 /**
 202  *      pm_suspend - Externally visible function for suspending system.
 203  *      @state:         Enumarted value of state to enter.
 204  *
 205  *      Determine whether or not value is within range, get state
 206  *      structure, and enter (above).
 207  */
 208
 209 int pm_suspend(suspend_state_t state)
 210 {
 211         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 212                 return enter_state(state);
 213         return -EINVAL;
 214 }
 215
 216
 217
 218 decl_subsys(power,NULL,NULL);
 219
 220
 221 /**
 222  *      state - control system power state.
 223  *
 224  *      show() returns what states are supported, which is hard-coded to
 225  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 226  *      'disk' (Suspend-to-Disk).
 227  *
 228  *      store() accepts one of those strings, translates it into the
 229  *      proper enumerated value, and initiates a suspend transition.
 230  */
 231
 232 static ssize_t state_show(struct subsystem * subsys, char * buf)
 233 {
 234         int i;
 235         char * s = buf;
 236
 237         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 238                 if (pm_states[i])
 239                         s += sprintf(s,"%s ",pm_states[i]);
 240         }
 241         s += sprintf(s,"\n");
 242         return (s - buf);
 243 }
 244
 245 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 246 {
 247         suspend_state_t state = PM_SUSPEND_STANDBY;
 248         char ** s;
 249         char *p;
 250         int error;
 251         int len;
 252
 253         p = memchr(buf, '\n', n);
 254         len = p ? p - buf : n;
 255
 256         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 257                 if (*s && !strncmp(buf, *s, len))
 258                         break;
 259         }
 260         if (*s)
 261                 error = enter_state(state);
 262         else
 263                 error = -EINVAL;
 264         return error ? error : n;
 265 }
 266
 267 power_attr(state);
 268
 269 static struct attribute * g[] = {
 270         &state_attr.attr,
 271         NULL,
 272 };
 273
 274 static struct attribute_group attr_group = {
 275         .attrs = g,
 276 };
 277
 278
 279 static int __init pm_init(void)
 280 {
 281         int error = subsystem_register(&power_subsys);
 282         if (!error)
 283                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 284         return error;
 285 }
 286
 287 core_initcall(pm_init);