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   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         error = device_prepare_suspend(PMSG_SUSPEND);
  61         if (error)
  62                 return error;
  63
  64         pm_prepare_console();
  65
  66         disable_nonboot_cpus();
  67
  68         if (num_online_cpus() != 1) {
  69                 error = -EPERM;
  70                 goto Enable_cpu;
  71         }
  72
  73         if (freeze_processes()) {
  74                 error = -EAGAIN;
  75                 goto Thaw;
  76         }
  77
  78         if ((free_pages = nr_free_pages()) < 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         if ((error = device_suspend(PMSG_SUSPEND))) {
  95                 printk(KERN_ERR "Some devices failed to suspend\n");
  96                 goto Finish;
  97         }
  98         return 0;
  99  Finish:
 100         if (pm_ops->finish)
 101                 pm_ops->finish(state);
 102  Thaw:
 103         thaw_processes();
 104  Enable_cpu:
 105         enable_nonboot_cpus();
 106         pm_restore_console();
 107         return error;
 108 }
 109
 110
 111 int suspend_enter(suspend_state_t state)
 112 {
 113         int error = 0;
 114         unsigned long flags;
 115
 116         local_irq_save(flags);
 117
 118         if ((error = device_power_down(PMSG_SUSPEND))) {
 119                 printk(KERN_ERR "Some devices failed to power down\n");
 120                 goto Done;
 121         }
 122         error = pm_ops->enter(state);
 123         device_power_up();
 124  Done:
 125         local_irq_restore(flags);
 126         return error;
 127 }
 128
 129
 130 /**
 131  *      suspend_finish - Do final work before exiting suspend sequence.
 132  *      @state:         State we're coming out of.
 133  *
 134  *      Call platform code to clean up, restart processes, and free the
 135  *      console that we've allocated. This is not called for suspend-to-disk.
 136  */
 137
 138 static void suspend_finish(suspend_state_t state)
 139 {
 140         device_resume();
 141         resume_console();
 142         thaw_processes();
 143         enable_nonboot_cpus();
 144         if (pm_ops && pm_ops->finish)
 145                 pm_ops->finish(state);
 146         pm_restore_console();
 147 }
 148
 149
 150
 151
 152 static const char * const pm_states[PM_SUSPEND_MAX] = {
 153         [PM_SUSPEND_STANDBY]    = "standby",
 154         [PM_SUSPEND_MEM]        = "mem",
 155 #ifdef CONFIG_SOFTWARE_SUSPEND
 156         [PM_SUSPEND_DISK]       = "disk",
 157 #endif
 158 };
 159
 160 static inline int valid_state(suspend_state_t state)
 161 {
 162         /* Suspend-to-disk does not really need low-level support.
 163          * It can work with reboot if needed. */
 164         if (state == PM_SUSPEND_DISK)
 165                 return 1;
 166
 167         if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
 168                 return 0;
 169         return 1;
 170 }
 171
 172
 173 /**
 174  *      enter_state - Do common work of entering low-power state.
 175  *      @state:         pm_state structure for state we're entering.
 176  *
 177  *      Make sure we're the only ones trying to enter a sleep state. Fail
 178  *      if someone has beat us to it, since we don't want anything weird to
 179  *      happen when we wake up.
 180  *      Then, do the setup for suspend, enter the state, and cleaup (after
 181  *      we've woken up).
 182  */
 183
 184 static int enter_state(suspend_state_t state)
 185 {
 186         int error;
 187
 188         if (!valid_state(state))
 189                 return -ENODEV;
 190         if (down_trylock(&pm_sem))
 191                 return -EBUSY;
 192
 193         if (state == PM_SUSPEND_DISK) {
 194                 error = pm_suspend_disk();
 195                 goto Unlock;
 196         }
 197
 198         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 199         if ((error = suspend_prepare(state)))
 200                 goto Unlock;
 201
 202         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 203         error = suspend_enter(state);
 204
 205         pr_debug("PM: Finishing wakeup.\n");
 206         suspend_finish(state);
 207  Unlock:
 208         up(&pm_sem);
 209         return error;
 210 }
 211
 212 /*
 213  * This is main interface to the outside world. It needs to be
 214  * called from process context.
 215  */
 216 int software_suspend(void)
 217 {
 218         return enter_state(PM_SUSPEND_DISK);
 219 }
 220
 221
 222 /**
 223  *      pm_suspend - Externally visible function for suspending system.
 224  *      @state:         Enumarted value of state to enter.
 225  *
 226  *      Determine whether or not value is within range, get state
 227  *      structure, and enter (above).
 228  */
 229
 230 int pm_suspend(suspend_state_t state)
 231 {
 232         if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
 233                 return enter_state(state);
 234         return -EINVAL;
 235 }
 236
 237
 238
 239 decl_subsys(power,NULL,NULL);
 240
 241
 242 /**
 243  *      state - control system power state.
 244  *
 245  *      show() returns what states are supported, which is hard-coded to
 246  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 247  *      'disk' (Suspend-to-Disk).
 248  *
 249  *      store() accepts one of those strings, translates it into the
 250  *      proper enumerated value, and initiates a suspend transition.
 251  */
 252
 253 static ssize_t state_show(struct subsystem * subsys, char * buf)
 254 {
 255         int i;
 256         char * s = buf;
 257
 258         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 259                 if (pm_states[i] && valid_state(i))
 260                         s += sprintf(s,"%s ", pm_states[i]);
 261         }
 262         s += sprintf(s,"\n");
 263         return (s - buf);
 264 }
 265
 266 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 267 {
 268         suspend_state_t state = PM_SUSPEND_STANDBY;
 269         const char * const *s;
 270         char *p;
 271         int error;
 272         int len;
 273
 274         p = memchr(buf, '\n', n);
 275         len = p ? p - buf : n;
 276
 277         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 278                 if (*s && !strncmp(buf, *s, len))
 279                         break;
 280         }
 281         if (state < PM_SUSPEND_MAX && *s)
 282                 error = enter_state(state);
 283         else
 284                 error = -EINVAL;
 285         return error ? error : n;
 286 }
 287
 288 power_attr(state);
 289
 290 static struct attribute * g[] = {
 291         &state_attr.attr,
 292         NULL,
 293 };
 294
 295 static struct attribute_group attr_group = {
 296         .attrs = g,
 297 };
 298
 299
 300 static int __init pm_init(void)
 301 {
 302         int error = subsystem_register(&power_subsys);
 303         if (!error)
 304                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 305         return error;
 306 }
 307
 308 core_initcall(pm_init);