kernel/power/user.c

   1 /*
   2  * linux/kernel/power/user.c
   3  *
   4  * This file provides the user space interface for software suspend/resume.
   5  *
   6  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  */
  11
  12 #include <linux/suspend.h>
  13 #include <linux/syscalls.h>
  14 #include <linux/string.h>
  15 #include <linux/device.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/mm.h>
  18 #include <linux/swap.h>
  19 #include <linux/swapops.h>
  20 #include <linux/pm.h>
  21 #include <linux/fs.h>
  22 #include <linux/console.h>
  23 #include <linux/cpu.h>
  24
  25 #include <asm/uaccess.h>
  26
  27 #include "power.h"
  28
  29 #define SNAPSHOT_MINOR  231
  30
  31 static struct snapshot_data {
  32         struct snapshot_handle handle;
  33         int swap;
  34         struct bitmap_page *bitmap;
  35         int mode;
  36         char frozen;
  37         char ready;
  38 } snapshot_state;
  39
  40 static atomic_t device_available = ATOMIC_INIT(1);
  41
  42 static int snapshot_open(struct inode *inode, struct file *filp)
  43 {
  44         struct snapshot_data *data;
  45
  46         if (!atomic_add_unless(&device_available, -1, 0))
  47                 return -EBUSY;
  48
  49         if ((filp->f_flags & O_ACCMODE) == O_RDWR)
  50                 return -ENOSYS;
  51
  52         nonseekable_open(inode, filp);
  53         data = &snapshot_state;
  54         filp->private_data = data;
  55         memset(&data->handle, 0, sizeof(struct snapshot_handle));
  56         if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
  57                 data->swap = swsusp_resume_device ? swap_type_of(swsusp_resume_device) : -1;
  58                 data->mode = O_RDONLY;
  59         } else {
  60                 data->swap = -1;
  61                 data->mode = O_WRONLY;
  62         }
  63         data->bitmap = NULL;
  64         data->frozen = 0;
  65         data->ready = 0;
  66
  67         return 0;
  68 }
  69
  70 static int snapshot_release(struct inode *inode, struct file *filp)
  71 {
  72         struct snapshot_data *data;
  73
  74         swsusp_free();
  75         data = filp->private_data;
  76         free_all_swap_pages(data->swap, data->bitmap);
  77         free_bitmap(data->bitmap);
  78         if (data->frozen) {
  79                 down(&pm_sem);
  80                 thaw_processes();
  81                 enable_nonboot_cpus();
  82                 up(&pm_sem);
  83         }
  84         atomic_inc(&device_available);
  85         return 0;
  86 }
  87
  88 static ssize_t snapshot_read(struct file *filp, char __user *buf,
  89                              size_t count, loff_t *offp)
  90 {
  91         struct snapshot_data *data;
  92         ssize_t res;
  93
  94         data = filp->private_data;
  95         res = snapshot_read_next(&data->handle, count);
  96         if (res > 0) {
  97                 if (copy_to_user(buf, data_of(data->handle), res))
  98                         res = -EFAULT;
  99                 else
 100                         *offp = data->handle.offset;
 101         }
 102         return res;
 103 }
 104
 105 static ssize_t snapshot_write(struct file *filp, const char __user *buf,
 106                               size_t count, loff_t *offp)
 107 {
 108         struct snapshot_data *data;
 109         ssize_t res;
 110
 111         data = filp->private_data;
 112         res = snapshot_write_next(&data->handle, count);
 113         if (res > 0) {
 114                 if (copy_from_user(data_of(data->handle), buf, res))
 115                         res = -EFAULT;
 116                 else
 117                         *offp = data->handle.offset;
 118         }
 119         return res;
 120 }
 121
 122 static int snapshot_ioctl(struct inode *inode, struct file *filp,
 123                           unsigned int cmd, unsigned long arg)
 124 {
 125         int error = 0;
 126         struct snapshot_data *data;
 127         loff_t offset, avail;
 128
 129         if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
 130                 return -ENOTTY;
 131         if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
 132                 return -ENOTTY;
 133         if (!capable(CAP_SYS_ADMIN))
 134                 return -EPERM;
 135
 136         data = filp->private_data;
 137
 138         switch (cmd) {
 139
 140         case SNAPSHOT_FREEZE:
 141                 if (data->frozen)
 142                         break;
 143                 down(&pm_sem);
 144                 error = disable_nonboot_cpus();
 145                 if (!error) {
 146                         error = freeze_processes();
 147                         if (error) {
 148                                 thaw_processes();
 149                                 enable_nonboot_cpus();
 150                                 error = -EBUSY;
 151                         }
 152                 }
 153                 up(&pm_sem);
 154                 if (!error)
 155                         data->frozen = 1;
 156                 break;
 157
 158         case SNAPSHOT_UNFREEZE:
 159                 if (!data->frozen)
 160                         break;
 161                 down(&pm_sem);
 162                 thaw_processes();
 163                 enable_nonboot_cpus();
 164                 up(&pm_sem);
 165                 data->frozen = 0;
 166                 break;
 167
 168         case SNAPSHOT_ATOMIC_SNAPSHOT:
 169                 if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
 170                         error = -EPERM;
 171                         break;
 172                 }
 173                 down(&pm_sem);
 174                 /* Free memory before shutting down devices. */
 175                 error = swsusp_shrink_memory();
 176                 if (!error) {
 177                         suspend_console();
 178                         error = device_suspend(PMSG_FREEZE);
 179                         if (!error) {
 180                                 in_suspend = 1;
 181                                 error = swsusp_suspend();
 182                                 device_resume();
 183                         }
 184                         resume_console();
 185                 }
 186                 up(&pm_sem);
 187                 if (!error)
 188                         error = put_user(in_suspend, (unsigned int __user *)arg);
 189                 if (!error)
 190                         data->ready = 1;
 191                 break;
 192
 193         case SNAPSHOT_ATOMIC_RESTORE:
 194                 if (data->mode != O_WRONLY || !data->frozen ||
 195                     !snapshot_image_loaded(&data->handle)) {
 196                         error = -EPERM;
 197                         break;
 198                 }
 199                 snapshot_free_unused_memory(&data->handle);
 200                 down(&pm_sem);
 201                 pm_prepare_console();
 202                 suspend_console();
 203                 error = device_suspend(PMSG_PRETHAW);
 204                 if (!error) {
 205                         error = swsusp_resume();
 206                         device_resume();
 207                 }
 208                 resume_console();
 209                 pm_restore_console();
 210                 up(&pm_sem);
 211                 break;
 212
 213         case SNAPSHOT_FREE:
 214                 swsusp_free();
 215                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 216                 data->ready = 0;
 217                 break;
 218
 219         case SNAPSHOT_SET_IMAGE_SIZE:
 220                 image_size = arg;
 221                 break;
 222
 223         case SNAPSHOT_AVAIL_SWAP:
 224                 avail = count_swap_pages(data->swap, 1);
 225                 avail <<= PAGE_SHIFT;
 226                 error = put_user(avail, (loff_t __user *)arg);
 227                 break;
 228
 229         case SNAPSHOT_GET_SWAP_PAGE:
 230                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 231                         error = -ENODEV;
 232                         break;
 233                 }
 234                 if (!data->bitmap) {
 235                         data->bitmap = alloc_bitmap(count_swap_pages(data->swap, 0));
 236                         if (!data->bitmap) {
 237                                 error = -ENOMEM;
 238                                 break;
 239                         }
 240                 }
 241                 offset = alloc_swap_page(data->swap, data->bitmap);
 242                 if (offset) {
 243                         offset <<= PAGE_SHIFT;
 244                         error = put_user(offset, (loff_t __user *)arg);
 245                 } else {
 246                         error = -ENOSPC;
 247                 }
 248                 break;
 249
 250         case SNAPSHOT_FREE_SWAP_PAGES:
 251                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 252                         error = -ENODEV;
 253                         break;
 254                 }
 255                 free_all_swap_pages(data->swap, data->bitmap);
 256                 free_bitmap(data->bitmap);
 257                 data->bitmap = NULL;
 258                 break;
 259
 260         case SNAPSHOT_SET_SWAP_FILE:
 261                 if (!data->bitmap) {
 262                         /*
 263                          * User space encodes device types as two-byte values,
 264                          * so we need to recode them
 265                          */
 266                         if (old_decode_dev(arg)) {
 267                                 data->swap = swap_type_of(old_decode_dev(arg));
 268                                 if (data->swap < 0)
 269                                         error = -ENODEV;
 270                         } else {
 271                                 data->swap = -1;
 272                                 error = -EINVAL;
 273                         }
 274                 } else {
 275                         error = -EPERM;
 276                 }
 277                 break;
 278
 279         case SNAPSHOT_S2RAM:
 280                 if (!data->frozen) {
 281                         error = -EPERM;
 282                         break;
 283                 }
 284
 285                 if (down_trylock(&pm_sem)) {
 286                         error = -EBUSY;
 287                         break;
 288                 }
 289
 290                 if (pm_ops->prepare) {
 291                         error = pm_ops->prepare(PM_SUSPEND_MEM);
 292                         if (error)
 293                                 goto OutS3;
 294                 }
 295
 296                 /* Put devices to sleep */
 297                 suspend_console();
 298                 error = device_suspend(PMSG_SUSPEND);
 299                 if (error) {
 300                         printk(KERN_ERR "Failed to suspend some devices.\n");
 301                 } else {
 302                         /* Enter S3, system is already frozen */
 303                         suspend_enter(PM_SUSPEND_MEM);
 304
 305                         /* Wake up devices */
 306                         device_resume();
 307                 }
 308                 resume_console();
 309                 if (pm_ops->finish)
 310                         pm_ops->finish(PM_SUSPEND_MEM);
 311
 312 OutS3:
 313                 up(&pm_sem);
 314                 break;
 315
 316         default:
 317                 error = -ENOTTY;
 318
 319         }
 320
 321         return error;
 322 }
 323
 324 static struct file_operations snapshot_fops = {
 325         .open = snapshot_open,
 326         .release = snapshot_release,
 327         .read = snapshot_read,
 328         .write = snapshot_write,
 329         .llseek = no_llseek,
 330         .ioctl = snapshot_ioctl,
 331 };
 332
 333 static struct miscdevice snapshot_device = {
 334         .minor = SNAPSHOT_MINOR,
 335         .name = "snapshot",
 336         .fops = &snapshot_fops,
 337 };
 338
 339 static int __init snapshot_device_init(void)
 340 {
 341         return misc_register(&snapshot_device);
 342 };
 343
 344 device_initcall(snapshot_device_init);