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