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/module.h>
  12 #include <linux/suspend.h>
  13 #include <linux/kobject.h>
  14 #include <linux/string.h>
  15 #include <linux/delay.h>
  16 #include <linux/errno.h>
  17 #include <linux/init.h>
  18 #include <linux/pm.h>
  19 #include <linux/console.h>
  20 #include <linux/cpu.h>
  21 #include <linux/resume-trace.h>
  22 #include <linux/freezer.h>
  23 #include <linux/vmstat.h>
  24
  25 #include "power.h"
  26
  27 /*This is just an arbitrary number */
  28 #define FREE_PAGE_NUMBER (100)
  29
  30 DEFINE_MUTEX(pm_mutex);
  31
  32 struct pm_ops *pm_ops;
  33 suspend_disk_method_t pm_disk_mode = PM_DISK_PLATFORM;
  34
  35 /**
  36  *      pm_set_ops - Set the global power method table.
  37  *      @ops:   Pointer to ops structure.
  38  */
  39
  40 void pm_set_ops(struct pm_ops * ops)
  41 {
  42         mutex_lock(&pm_mutex);
  43         pm_ops = ops;
  44         mutex_unlock(&pm_mutex);
  45 }
  46
  47 static inline void pm_finish(suspend_state_t state)
  48 {
  49         if (pm_ops->finish)
  50                 pm_ops->finish(state);
  51 }
  52
  53 /**
  54  *      suspend_prepare - Do prep work before entering low-power state.
  55  *      @state:         State we're entering.
  56  *
  57  *      This is common code that is called for each state that we're
  58  *      entering. Allocate a console, stop all processes, then make sure
  59  *      the platform can enter the requested state.
  60  */
  61
  62 static int suspend_prepare(suspend_state_t state)
  63 {
  64         int error;
  65         unsigned int free_pages;
  66
  67         if (!pm_ops || !pm_ops->enter)
  68                 return -EPERM;
  69
  70         pm_prepare_console();
  71
  72         if (freeze_processes()) {
  73                 error = -EAGAIN;
  74                 goto Thaw;
  75         }
  76
  77         if ((free_pages = global_page_state(NR_FREE_PAGES))
  78                         < FREE_PAGE_NUMBER) {
  79                 pr_debug("PM: free some memory\n");
  80                 shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
  81                 if (nr_free_pages() < FREE_PAGE_NUMBER) {
  82                         error = -ENOMEM;
  83                         printk(KERN_ERR "PM: No enough memory\n");
  84                         goto Thaw;
  85                 }
  86         }
  87
  88         if (pm_ops->prepare) {
  89                 if ((error = pm_ops->prepare(state)))
  90                         goto Thaw;
  91         }
  92
  93         suspend_console();
  94         error = device_suspend(PMSG_SUSPEND);
  95         if (error) {
  96                 printk(KERN_ERR "Some devices failed to suspend\n");
  97                 goto Resume_devices;
  98         }
  99         error = disable_nonboot_cpus();
 100         if (!error)
 101                 return 0;
 102
 103         enable_nonboot_cpus();
 104  Resume_devices:
 105         pm_finish(state);
 106         device_resume();
 107         resume_console();
 108  Thaw:
 109         thaw_processes();
 110         pm_restore_console();
 111         return error;
 112 }
 113
 114
 115 int suspend_enter(suspend_state_t state)
 116 {
 117         int error = 0;
 118         unsigned long flags;
 119
 120         local_irq_save(flags);
 121
 122         if ((error = device_power_down(PMSG_SUSPEND))) {
 123                 printk(KERN_ERR "Some devices failed to power down\n");
 124                 goto Done;
 125         }
 126         error = pm_ops->enter(state);
 127         device_power_up();
 128  Done:
 129         local_irq_restore(flags);
 130         return error;
 131 }
 132
 133
 134 /**
 135  *      suspend_finish - Do final work before exiting suspend sequence.
 136  *      @state:         State we're coming out of.
 137  *
 138  *      Call platform code to clean up, restart processes, and free the
 139  *      console that we've allocated. This is not called for suspend-to-disk.
 140  */
 141
 142 static void suspend_finish(suspend_state_t state)
 143 {
 144         enable_nonboot_cpus();
 145         pm_finish(state);
 146         device_resume();
 147         resume_console();
 148         thaw_processes();
 149         pm_restore_console();
 150 }
 151
 152
 153
 154
 155 static const char * const pm_states[PM_SUSPEND_MAX] = {
 156         [PM_SUSPEND_STANDBY]    = "standby",
 157         [PM_SUSPEND_MEM]        = "mem",
 158 #ifdef CONFIG_SOFTWARE_SUSPEND
 159         [PM_SUSPEND_DISK]       = "disk",
 160 #endif
 161 };
 162
 163 static inline int valid_state(suspend_state_t state)
 164 {
 165         /* Suspend-to-disk does not really need low-level support.
 166          * It can work with reboot if needed. */
 167         if (state == PM_SUSPEND_DISK)
 168                 return 1;
 169
 170         /* all other states need lowlevel support and need to be
 171          * valid to the lowlevel implementation, no valid callback
 172          * implies that all are valid. */
 173         if (!pm_ops || (pm_ops->valid && !pm_ops->valid(state)))
 174                 return 0;
 175         return 1;
 176 }
 177
 178
 179 /**
 180  *      enter_state - Do common work of entering low-power state.
 181  *      @state:         pm_state structure for state we're entering.
 182  *
 183  *      Make sure we're the only ones trying to enter a sleep state. Fail
 184  *      if someone has beat us to it, since we don't want anything weird to
 185  *      happen when we wake up.
 186  *      Then, do the setup for suspend, enter the state, and cleaup (after
 187  *      we've woken up).
 188  */
 189
 190 static int enter_state(suspend_state_t state)
 191 {
 192         int error;
 193
 194         if (!valid_state(state))
 195                 return -ENODEV;
 196         if (!mutex_trylock(&pm_mutex))
 197                 return -EBUSY;
 198
 199         if (state == PM_SUSPEND_DISK) {
 200                 error = pm_suspend_disk();
 201                 goto Unlock;
 202         }
 203
 204         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 205         if ((error = suspend_prepare(state)))
 206                 goto Unlock;
 207
 208         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 209         error = suspend_enter(state);
 210
 211         pr_debug("PM: Finishing wakeup.\n");
 212         suspend_finish(state);
 213  Unlock:
 214         mutex_unlock(&pm_mutex);
 215         return error;
 216 }
 217
 218 /*
 219  * This is main interface to the outside world. It needs to be
 220  * called from process context.
 221  */
 222 int software_suspend(void)
 223 {
 224         return enter_state(PM_SUSPEND_DISK);
 225 }
 226
 227
 228 /**
 229  *      pm_suspend - Externally visible function for suspending system.
 230  *      @state:         Enumarted value of state to enter.
 231  *
 232  *      Determine whether or not value is within range, get state
 233  *      structure, and enter (above).
 234  */
 235
 236 int pm_suspend(suspend_state_t state)
 237 {
 238         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 239                 return enter_state(state);
 240         return -EINVAL;
 241 }
 242
 243 EXPORT_SYMBOL(pm_suspend);
 244
 245 decl_subsys(power,NULL,NULL);
 246
 247
 248 /**
 249  *      state - control system power state.
 250  *
 251  *      show() returns what states are supported, which is hard-coded to
 252  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 253  *      'disk' (Suspend-to-Disk).
 254  *
 255  *      store() accepts one of those strings, translates it into the
 256  *      proper enumerated value, and initiates a suspend transition.
 257  */
 258
 259 static ssize_t state_show(struct subsystem * subsys, char * buf)
 260 {
 261         int i;
 262         char * s = buf;
 263
 264         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 265                 if (pm_states[i] && valid_state(i))
 266                         s += sprintf(s,"%s ", pm_states[i]);
 267         }
 268         s += sprintf(s,"\n");
 269         return (s - buf);
 270 }
 271
 272 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 273 {
 274         suspend_state_t state = PM_SUSPEND_STANDBY;
 275         const char * const *s;
 276         char *p;
 277         int error;
 278         int len;
 279
 280         p = memchr(buf, '\n', n);
 281         len = p ? p - buf : n;
 282
 283         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 284                 if (*s && !strncmp(buf, *s, len))
 285                         break;
 286         }
 287         if (state < PM_SUSPEND_MAX && *s)
 288                 error = enter_state(state);
 289         else
 290                 error = -EINVAL;
 291         return error ? error : n;
 292 }
 293
 294 power_attr(state);
 295
 296 #ifdef CONFIG_PM_TRACE
 297 int pm_trace_enabled;
 298
 299 static ssize_t pm_trace_show(struct subsystem * subsys, char * buf)
 300 {
 301         return sprintf(buf, "%d\n", pm_trace_enabled);
 302 }
 303
 304 static ssize_t
 305 pm_trace_store(struct subsystem * subsys, const char * buf, size_t n)
 306 {
 307         int val;
 308
 309         if (sscanf(buf, "%d", &val) == 1) {
 310                 pm_trace_enabled = !!val;
 311                 return n;
 312         }
 313         return -EINVAL;
 314 }
 315
 316 power_attr(pm_trace);
 317
 318 static struct attribute * g[] = {
 319         &state_attr.attr,
 320         &pm_trace_attr.attr,
 321         NULL,
 322 };
 323 #else
 324 static struct attribute * g[] = {
 325         &state_attr.attr,
 326         NULL,
 327 };
 328 #endif /* CONFIG_PM_TRACE */
 329
 330 static struct attribute_group attr_group = {
 331         .attrs = g,
 332 };
 333
 334
 335 static int __init pm_init(void)
 336 {
 337         int error = subsystem_register(&power_subsys);
 338         if (!error)
 339                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 340         return error;
 341 }
 342
 343 core_initcall(pm_init);