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 DECLARE_MUTEX(pm_sem);
  23
  24 struct pm_ops * pm_ops = NULL;
  25 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
  26
  27 /**
  28  *      pm_set_ops - Set the global power method table.
  29  *      @ops:   Pointer to ops structure.
  30  */
  31
  32 void pm_set_ops(struct pm_ops * ops)
  33 {
  34         down(&pm_sem);
  35         pm_ops = ops;
  36         up(&pm_sem);
  37 }
  38
  39
  40 /**
  41  *      suspend_prepare - Do prep work before entering low-power state.
  42  *      @state:         State we're entering.
  43  *
  44  *      This is common code that is called for each state that we're
  45  *      entering. Allocate a console, stop all processes, then make sure
  46  *      the platform can enter the requested state.
  47  */
  48
  49 static int suspend_prepare(suspend_state_t state)
  50 {
  51         int error = 0;
  52
  53         if (!pm_ops || !pm_ops->enter)
  54                 return -EPERM;
  55
  56         pm_prepare_console();
  57
  58         disable_nonboot_cpus();
  59
  60         if (num_online_cpus() != 1) {
  61                 error = -EPERM;
  62                 goto Enable_cpu;
  63         }
  64
  65         if (freeze_processes()) {
  66                 error = -EAGAIN;
  67                 goto Thaw;
  68         }
  69
  70         if (pm_ops->prepare) {
  71                 if ((error = pm_ops->prepare(state)))
  72                         goto Thaw;
  73         }
  74
  75         if ((error = device_suspend(PMSG_SUSPEND))) {
  76                 printk(KERN_ERR "Some devices failed to suspend\n");
  77                 goto Finish;
  78         }
  79         return 0;
  80  Finish:
  81         if (pm_ops->finish)
  82                 pm_ops->finish(state);
  83  Thaw:
  84         thaw_processes();
  85  Enable_cpu:
  86         enable_nonboot_cpus();
  87         pm_restore_console();
  88         return error;
  89 }
  90
  91
  92 static int suspend_enter(suspend_state_t state)
  93 {
  94         int error = 0;
  95         unsigned long flags;
  96
  97         local_irq_save(flags);
  98
  99         if ((error = device_power_down(PMSG_SUSPEND))) {
 100                 printk(KERN_ERR "Some devices failed to power down\n");
 101                 goto Done;
 102         }
 103         error = pm_ops->enter(state);
 104         device_power_up();
 105  Done:
 106         local_irq_restore(flags);
 107         return error;
 108 }
 109
 110
 111 /**
 112  *      suspend_finish - Do final work before exiting suspend sequence.
 113  *      @state:         State we're coming out of.
 114  *
 115  *      Call platform code to clean up, restart processes, and free the
 116  *      console that we've allocated. This is not called for suspend-to-disk.
 117  */
 118
 119 static void suspend_finish(suspend_state_t state)
 120 {
 121         device_resume();
 122         if (pm_ops && pm_ops->finish)
 123                 pm_ops->finish(state);
 124         thaw_processes();
 125         enable_nonboot_cpus();
 126         pm_restore_console();
 127 }
 128
 129
 130
 131
 132 static char * pm_states[] = {
 133         [PM_SUSPEND_STANDBY]    = "standby",
 134         [PM_SUSPEND_MEM]        = "mem",
 135         [PM_SUSPEND_DISK]       = "disk",
 136         NULL,
 137 };
 138
 139
 140 /**
 141  *      enter_state - Do common work of entering low-power state.
 142  *      @state:         pm_state structure for state we're entering.
 143  *
 144  *      Make sure we're the only ones trying to enter a sleep state. Fail
 145  *      if someone has beat us to it, since we don't want anything weird to
 146  *      happen when we wake up.
 147  *      Then, do the setup for suspend, enter the state, and cleaup (after
 148  *      we've woken up).
 149  */
 150
 151 static int enter_state(suspend_state_t state)
 152 {
 153         int error;
 154
 155         if (down_trylock(&pm_sem))
 156                 return -EBUSY;
 157
 158         if (state == PM_SUSPEND_DISK) {
 159                 error = pm_suspend_disk();
 160                 goto Unlock;
 161         }
 162
 163         pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
 164         if ((error = suspend_prepare(state)))
 165                 goto Unlock;
 166
 167         pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 168         error = suspend_enter(state);
 169
 170         pr_debug("PM: Finishing wakeup.\n");
 171         suspend_finish(state);
 172  Unlock:
 173         up(&pm_sem);
 174         return error;
 175 }
 176
 177 /*
 178  * This is main interface to the outside world. It needs to be
 179  * called from process context.
 180  */
 181 int software_suspend(void)
 182 {
 183         return enter_state(PM_SUSPEND_DISK);
 184 }
 185
 186
 187 /**
 188  *      pm_suspend - Externally visible function for suspending system.
 189  *      @state:         Enumarted value of state to enter.
 190  *
 191  *      Determine whether or not value is within range, get state
 192  *      structure, and enter (above).
 193  */
 194
 195 int pm_suspend(suspend_state_t state)
 196 {
 197         if (state > PM_SUSPEND_ON && state < PM_SUSPEND_MAX)
 198                 return enter_state(state);
 199         return -EINVAL;
 200 }
 201
 202
 203
 204 decl_subsys(power,NULL,NULL);
 205
 206
 207 /**
 208  *      state - control system power state.
 209  *
 210  *      show() returns what states are supported, which is hard-coded to
 211  *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 212  *      'disk' (Suspend-to-Disk).
 213  *
 214  *      store() accepts one of those strings, translates it into the
 215  *      proper enumerated value, and initiates a suspend transition.
 216  */
 217
 218 static ssize_t state_show(struct subsystem * subsys, char * buf)
 219 {
 220         int i;
 221         char * s = buf;
 222
 223         for (i = 0; i < PM_SUSPEND_MAX; i++) {
 224                 if (pm_states[i])
 225                         s += sprintf(s,"%s ",pm_states[i]);
 226         }
 227         s += sprintf(s,"\n");
 228         return (s - buf);
 229 }
 230
 231 static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
 232 {
 233         suspend_state_t state = PM_SUSPEND_STANDBY;
 234         char ** s;
 235         char *p;
 236         int error;
 237         int len;
 238
 239         p = memchr(buf, '\n', n);
 240         len = p ? p - buf : n;
 241
 242         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
 243                 if (*s && !strncmp(buf, *s, len))
 244                         break;
 245         }
 246         if (*s)
 247                 error = enter_state(state);
 248         else
 249                 error = -EINVAL;
 250         return error ? error : n;
 251 }
 252
 253 power_attr(state);
 254
 255 static struct attribute * g[] = {
 256         &state_attr.attr,
 257         NULL,
 258 };
 259
 260 static struct attribute_group attr_group = {
 261         .attrs = g,
 262 };
 263
 264
 265 static int __init pm_init(void)
 266 {
 267         int error = subsystem_register(&power_subsys);
 268         if (!error)
 269                 error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
 270         return error;
 271 }
 272
 273 core_initcall(pm_init);