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 /* default implementation */
 115 void __attribute__ ((weak)) arch_suspend_disable_irqs(void)
 116 {
 117         local_irq_disable();
 118 }
 119
 120 /* default implementation */
 121 void __attribute__ ((weak)) arch_suspend_enable_irqs(void)
 122 {
 123         local_irq_enable();
 124 }
 125
 126 int suspend_enter(suspend_state_t state)
 127 {
 128         int error = 0;
 129
 130         arch_suspend_disable_irqs();
 131         BUG_ON(!irqs_disabled());
 132
 133         if ((error = device_power_down(PMSG_SUSPEND))) {
 134                 printk(KERN_ERR "Some devices failed to power down\n");
 135                 goto Done;
 136         }
 137         error = pm_ops->enter(state);
 138         device_power_up();
 139  Done:
 140         arch_suspend_enable_irqs();
 141         BUG_ON(irqs_disabled());
 142         return error;
 143 }
 144
 145
 146 /**
 147  *      suspend_finish - Do final work before exiting suspend sequence.
 148  *      @state:         State we're coming out of.
 149  *
 150  *      Call platform code to clean up, restart processes, and free the
 151  *      console that we've allocated. This is not called for suspend-to-disk.
 152  */
 153
 154 static void suspend_finish(suspend_state_t state)
 155 {
 156         enable_nonboot_cpus();
 157         pm_finish(state);
 158         device_resume();
 159         resume_console();
 160         thaw_processes();
 161         pm_restore_console();
 162 }
 163
 164
 165
 166
 167 static const char * const pm_states[PM_SUSPEND_MAX] = {
 168         [PM_SUSPEND_STANDBY]    = "standby",
 169         [PM_SUSPEND_MEM]        = "mem",
 170 #ifdef CONFIG_SOFTWARE_SUSPEND
 171         [PM_SUSPEND_DISK]       = "disk",
 172 #endif
 173 };
 174
 175 static inline int valid_state(suspend_state_t state)
 176 {
 177         /* Suspend-to-disk does not really need low-level support.
 178          * It can work with reboot if needed. */
 179         if (state == PM_SUSPEND_DISK)
 180                 return 1;
 181
 182         /* all other states need lowlevel support and need to be
 183          * valid to the lowlevel implementation, no valid callback
 184          * implies that all are valid. */
 185         if (!pm_ops || (pm_ops->valid && !pm_ops->valid(state)))
 186                 return 0;
 187         return 1;
 188 }
 189
 190
 191 /**
 192  *      enter_state - Do common work of entering low-power state.
 193  *      @state:         pm_state structure for state we're entering.
 194  *
 195  *      Make sure we're the only ones trying to enter a sleep state. Fail
 196  *      if someone has beat us to it, since we don't want anything weird to
 197  *      happen when we wake up.
 198  *      Then, do the setup for suspend, enter the state, and cleaup (after
 199  *      we've woken up).
 200  */
 201
 202 static int enter_state(suspend_state_t state)
 203 {
 204         int error;
 205
 206         if (!valid_state(state))
 207                 return -ENODEV;
 208         if (!mutex_trylock(&pm_mutex))
 209                 return -EBUSY;
 210
 211         if (state == PM_SUSPEND_DISK) {
 212                 error = pm_suspend_disk();
 213                 goto Unlock;
 214         }
 215
 216         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 217         if ((error = suspend_prepare(state)))
 218                 goto Unlock;
 219
 220         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 221         error = suspend_enter(state);
 222
 223         pr_debug("PM: Finishing wakeup.\n");
 224         suspend_finish(state);
 225  Unlock:
 226         mutex_unlock(&pm_mutex);
 227         return error;
 228 }
 229
 230 /*
 231  * This is main interface to the outside world. It needs to be
 232  * called from process context.
 233  */
 234 int software_suspend(void)
 235 {
 236         return enter_state(PM_SUSPEND_DISK);
 237 }
 238
 239
 240 /**
 241  *      pm_suspend - Externally visible function for suspending system.
 242  *      @state:         Enumarted value of state to enter.
 243  *
 244  *      Determine whether or not value is within range, get state
 245  *      structure, and enter (above).
 246  */
 247
 248 int pm_suspend(suspend_state_t state)
 249 {
 250         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 251                 return enter_state(state);
 252         return -EINVAL;
 253 }
 254
 255 EXPORT_SYMBOL(pm_suspend);
 256
 257 decl_subsys(power,NULL,NULL);
 258
 259
 260 /**
 261  *      state - control system power state.
 262  *
 263  *      show() returns what states are supported, which is hard-coded to
 264  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 265  *      'disk' (Suspend-to-Disk).
 266  *
 267  *      store() accepts one of those strings, translates it into the
 268  *      proper enumerated value, and initiates a suspend transition.
 269  */
 270
 271 static ssize_t state_show(struct subsystem * subsys, char * buf)
 272 {
 273         int i;
 274         char * s = buf;
 275
 276         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 277                 if (pm_states[i] && valid_state(i))
 278                         s += sprintf(s,"%s ", pm_states[i]);
 279         }
 280         s += sprintf(s,"\n");
 281         return (s - buf);
 282 }
 283
 284 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 285 {
 286         suspend_state_t state = PM_SUSPEND_STANDBY;
 287         const char * const *s;
 288         char *p;
 289         int error;
 290         int len;
 291
 292         p = memchr(buf, '\n', n);
 293         len = p ? p - buf : n;
 294
 295         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 296                 if (*s && !strncmp(buf, *s, len))
 297                         break;
 298         }
 299         if (state < PM_SUSPEND_MAX && *s)
 300                 error = enter_state(state);
 301         else
 302                 error = -EINVAL;
 303         return error ? error : n;
 304 }
 305
 306 power_attr(state);
 307
 308 #ifdef CONFIG_PM_TRACE
 309 int pm_trace_enabled;
 310
 311 static ssize_t pm_trace_show(struct subsystem * subsys, char * buf)
 312 {
 313         return sprintf(buf, "%d\n", pm_trace_enabled);
 314 }
 315
 316 static ssize_t
 317 pm_trace_store(struct subsystem * subsys, const char * buf, size_t n)
 318 {
 319         int val;
 320
 321         if (sscanf(buf, "%d", &val) == 1) {
 322                 pm_trace_enabled = !!val;
 323                 return n;
 324         }
 325         return -EINVAL;
 326 }
 327
 328 power_attr(pm_trace);
 329
 330 static struct attribute * g[] = {
 331         &state_attr.attr,
 332         &pm_trace_attr.attr,
 333         NULL,
 334 };
 335 #else
 336 static struct attribute * g[] = {
 337         &state_attr.attr,
 338         NULL,
 339 };
 340 #endif /* CONFIG_PM_TRACE */
 341
 342 static struct attribute_group attr_group = {
 343         .attrs = g,
 344 };
 345
 346
 347 static int __init pm_init(void)
 348 {
 349         int error = subsystem_register(&power_subsys);
 350         if (!error)
 351                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 352         return error;
 353 }
 354
 355 core_initcall(pm_init);