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
  34 /**
  35  *      pm_set_ops - Set the global power method table.
  36  *      @ops:   Pointer to ops structure.
  37  */
  38
  39 void pm_set_ops(struct pm_ops * ops)
  40 {
  41         mutex_lock(&pm_mutex);
  42         pm_ops = ops;
  43         mutex_unlock(&pm_mutex);
  44 }
  45
  46 /**
  47  * pm_valid_only_mem - generic memory-only valid callback
  48  *
  49  * pm_ops drivers that implement mem suspend only and only need
  50  * to check for that in their .valid callback can use this instead
  51  * of rolling their own .valid callback.
  52  */
  53 int pm_valid_only_mem(suspend_state_t state)
  54 {
  55         return state == PM_SUSPEND_MEM;
  56 }
  57
  58
  59 static inline void pm_finish(suspend_state_t state)
  60 {
  61         if (pm_ops->finish)
  62                 pm_ops->finish(state);
  63 }
  64
  65 /**
  66  *      suspend_prepare - Do prep work before entering low-power state.
  67  *      @state:         State we're entering.
  68  *
  69  *      This is common code that is called for each state that we're
  70  *      entering. Allocate a console, stop all processes, then make sure
  71  *      the platform can enter the requested state.
  72  */
  73
  74 static int suspend_prepare(suspend_state_t state)
  75 {
  76         int error;
  77         unsigned int free_pages;
  78
  79         if (!pm_ops || !pm_ops->enter)
  80                 return -EPERM;
  81
  82         pm_prepare_console();
  83
  84         if (freeze_processes()) {
  85                 error = -EAGAIN;
  86                 goto Thaw;
  87         }
  88
  89         if ((free_pages = global_page_state(NR_FREE_PAGES))
  90                         < FREE_PAGE_NUMBER) {
  91                 pr_debug("PM: free some memory\n");
  92                 shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
  93                 if (nr_free_pages() < FREE_PAGE_NUMBER) {
  94                         error = -ENOMEM;
  95                         printk(KERN_ERR "PM: No enough memory\n");
  96                         goto Thaw;
  97                 }
  98         }
  99
 100         if (pm_ops->prepare) {
 101                 if ((error = pm_ops->prepare(state)))
 102                         goto Thaw;
 103         }
 104
 105         suspend_console();
 106         error = device_suspend(PMSG_SUSPEND);
 107         if (error) {
 108                 printk(KERN_ERR "Some devices failed to suspend\n");
 109                 goto Resume_devices;
 110         }
 111         error = disable_nonboot_cpus();
 112         if (!error)
 113                 return 0;
 114
 115         enable_nonboot_cpus();
 116  Resume_devices:
 117         pm_finish(state);
 118         device_resume();
 119         resume_console();
 120  Thaw:
 121         thaw_processes();
 122         pm_restore_console();
 123         return error;
 124 }
 125
 126 /* default implementation */
 127 void __attribute__ ((weak)) arch_suspend_disable_irqs(void)
 128 {
 129         local_irq_disable();
 130 }
 131
 132 /* default implementation */
 133 void __attribute__ ((weak)) arch_suspend_enable_irqs(void)
 134 {
 135         local_irq_enable();
 136 }
 137
 138 int suspend_enter(suspend_state_t state)
 139 {
 140         int error = 0;
 141
 142         arch_suspend_disable_irqs();
 143         BUG_ON(!irqs_disabled());
 144
 145         if ((error = device_power_down(PMSG_SUSPEND))) {
 146                 printk(KERN_ERR "Some devices failed to power down\n");
 147                 goto Done;
 148         }
 149         error = pm_ops->enter(state);
 150         device_power_up();
 151  Done:
 152         arch_suspend_enable_irqs();
 153         BUG_ON(irqs_disabled());
 154         return error;
 155 }
 156
 157
 158 /**
 159  *      suspend_finish - Do final work before exiting suspend sequence.
 160  *      @state:         State we're coming out of.
 161  *
 162  *      Call platform code to clean up, restart processes, and free the
 163  *      console that we've allocated. This is not called for suspend-to-disk.
 164  */
 165
 166 static void suspend_finish(suspend_state_t state)
 167 {
 168         enable_nonboot_cpus();
 169         pm_finish(state);
 170         device_resume();
 171         resume_console();
 172         thaw_processes();
 173         pm_restore_console();
 174 }
 175
 176
 177
 178
 179 static const char * const pm_states[PM_SUSPEND_MAX] = {
 180         [PM_SUSPEND_STANDBY]    = "standby",
 181         [PM_SUSPEND_MEM]        = "mem",
 182 };
 183
 184 static inline int valid_state(suspend_state_t state)
 185 {
 186         /* All states need lowlevel support and need to be valid
 187          * to the lowlevel implementation, no valid callback
 188          * implies that none are valid. */
 189         if (!pm_ops || !pm_ops->valid || !pm_ops->valid(state))
 190                 return 0;
 191         return 1;
 192 }
 193
 194
 195 /**
 196  *      enter_state - Do common work of entering low-power state.
 197  *      @state:         pm_state structure for state we're entering.
 198  *
 199  *      Make sure we're the only ones trying to enter a sleep state. Fail
 200  *      if someone has beat us to it, since we don't want anything weird to
 201  *      happen when we wake up.
 202  *      Then, do the setup for suspend, enter the state, and cleaup (after
 203  *      we've woken up).
 204  */
 205
 206 static int enter_state(suspend_state_t state)
 207 {
 208         int error;
 209
 210         if (!valid_state(state))
 211                 return -ENODEV;
 212         if (!mutex_trylock(&pm_mutex))
 213                 return -EBUSY;
 214
 215         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 216         if ((error = suspend_prepare(state)))
 217                 goto Unlock;
 218
 219         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 220         error = suspend_enter(state);
 221
 222         pr_debug("PM: Finishing wakeup.\n");
 223         suspend_finish(state);
 224  Unlock:
 225         mutex_unlock(&pm_mutex);
 226         return error;
 227 }
 228
 229
 230 /**
 231  *      pm_suspend - Externally visible function for suspending system.
 232  *      @state:         Enumerated value of state to enter.
 233  *
 234  *      Determine whether or not value is within range, get state
 235  *      structure, and enter (above).
 236  */
 237
 238 int pm_suspend(suspend_state_t state)
 239 {
 240         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 241                 return enter_state(state);
 242         return -EINVAL;
 243 }
 244
 245 EXPORT_SYMBOL(pm_suspend);
 246
 247 decl_subsys(power,NULL,NULL);
 248
 249
 250 /**
 251  *      state - control system power state.
 252  *
 253  *      show() returns what states are supported, which is hard-coded to
 254  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 255  *      'disk' (Suspend-to-Disk).
 256  *
 257  *      store() accepts one of those strings, translates it into the
 258  *      proper enumerated value, and initiates a suspend transition.
 259  */
 260
 261 static ssize_t state_show(struct kset *kset, char *buf)
 262 {
 263         int i;
 264         char * s = buf;
 265
 266         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 267                 if (pm_states[i] && valid_state(i))
 268                         s += sprintf(s,"%s ", pm_states[i]);
 269         }
 270 #ifdef CONFIG_SOFTWARE_SUSPEND
 271         s += sprintf(s, "%s\n", "disk");
 272 #else
 273         if (s != buf)
 274                 /* convert the last space to a newline */
 275                 *(s-1) = '\n';
 276 #endif
 277         return (s - buf);
 278 }
 279
 280 static ssize_t state_store(struct kset *kset, const char *buf, size_t n)
 281 {
 282         suspend_state_t state = PM_SUSPEND_STANDBY;
 283         const char * const *s;
 284         char *p;
 285         int error;
 286         int len;
 287
 288         p = memchr(buf, '\n', n);
 289         len = p ? p - buf : n;
 290
 291         /* First, check if we are requested to hibernate */
 292         if (!strncmp(buf, "disk", len)) {
 293                 error = hibernate();
 294                 return error ? error : n;
 295         }
 296
 297         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 298                 if (*s && !strncmp(buf, *s, len))
 299                         break;
 300         }
 301         if (state < PM_SUSPEND_MAX && *s)
 302                 error = enter_state(state);
 303         else
 304                 error = -EINVAL;
 305         return error ? error : n;
 306 }
 307
 308 power_attr(state);
 309
 310 #ifdef CONFIG_PM_TRACE
 311 int pm_trace_enabled;
 312
 313 static ssize_t pm_trace_show(struct kset *kset, char *buf)
 314 {
 315         return sprintf(buf, "%d\n", pm_trace_enabled);
 316 }
 317
 318 static ssize_t
 319 pm_trace_store(struct kset *kset, const char *buf, size_t n)
 320 {
 321         int val;
 322
 323         if (sscanf(buf, "%d", &val) == 1) {
 324                 pm_trace_enabled = !!val;
 325                 return n;
 326         }
 327         return -EINVAL;
 328 }
 329
 330 power_attr(pm_trace);
 331
 332 static struct attribute * g[] = {
 333         &state_attr.attr,
 334         &pm_trace_attr.attr,
 335         NULL,
 336 };
 337 #else
 338 static struct attribute * g[] = {
 339         &state_attr.attr,
 340         NULL,
 341 };
 342 #endif /* CONFIG_PM_TRACE */
 343
 344 static struct attribute_group attr_group = {
 345         .attrs = g,
 346 };
 347
 348
 349 static int __init pm_init(void)
 350 {
 351         int error = subsystem_register(&power_subsys);
 352         if (!error)
 353                 error = sysfs_create_group(&power_subsys.kobj,&attr_group);
 354         return error;
 355 }
 356
 357 core_initcall(pm_init);