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                 snapshot_free_unused_memory(&data->handle);
 197                 down(&pm_sem);
 198                 pm_prepare_console();
 199                 error = device_suspend(PMSG_PRETHAW);
 200                 if (!error) {
 201                         error = swsusp_resume();
 202                         device_resume();
 203                 }
 204                 pm_restore_console();
 205                 up(&pm_sem);
 206                 break;
 207
 208         case SNAPSHOT_FREE:
 209                 swsusp_free();
 210                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
 211                 data->ready = 0;
 212                 break;
 213
 214         case SNAPSHOT_SET_IMAGE_SIZE:
 215                 image_size = arg;
 216                 break;
 217
 218         case SNAPSHOT_AVAIL_SWAP:
 219                 avail = count_swap_pages(data->swap, 1);
 220                 avail <<= PAGE_SHIFT;
 221                 error = put_user(avail, (loff_t __user *)arg);
 222                 break;
 223
 224         case SNAPSHOT_GET_SWAP_PAGE:
 225                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 226                         error = -ENODEV;
 227                         break;
 228                 }
 229                 if (!data->bitmap) {
 230                         data->bitmap = alloc_bitmap(count_swap_pages(data->swap, 0));
 231                         if (!data->bitmap) {
 232                                 error = -ENOMEM;
 233                                 break;
 234                         }
 235                 }
 236                 offset = alloc_swap_page(data->swap, data->bitmap);
 237                 if (offset) {
 238                         offset <<= PAGE_SHIFT;
 239                         error = put_user(offset, (loff_t __user *)arg);
 240                 } else {
 241                         error = -ENOSPC;
 242                 }
 243                 break;
 244
 245         case SNAPSHOT_FREE_SWAP_PAGES:
 246                 if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
 247                         error = -ENODEV;
 248                         break;
 249                 }
 250                 free_all_swap_pages(data->swap, data->bitmap);
 251                 free_bitmap(data->bitmap);
 252                 data->bitmap = NULL;
 253                 break;
 254
 255         case SNAPSHOT_SET_SWAP_FILE:
 256                 if (!data->bitmap) {
 257                         /*
 258                          * User space encodes device types as two-byte values,
 259                          * so we need to recode them
 260                          */
 261                         if (old_decode_dev(arg)) {
 262                                 data->swap = swap_type_of(old_decode_dev(arg));
 263                                 if (data->swap < 0)
 264                                         error = -ENODEV;
 265                         } else {
 266                                 data->swap = -1;
 267                                 error = -EINVAL;
 268                         }
 269                 } else {
 270                         error = -EPERM;
 271                 }
 272                 break;
 273
 274         case SNAPSHOT_S2RAM:
 275                 if (!data->frozen) {
 276                         error = -EPERM;
 277                         break;
 278                 }
 279
 280                 if (down_trylock(&pm_sem)) {
 281                         error = -EBUSY;
 282                         break;
 283                 }
 284
 285                 if (pm_ops->prepare) {
 286                         error = pm_ops->prepare(PM_SUSPEND_MEM);
 287                         if (error)
 288                                 goto OutS3;
 289                 }
 290
 291                 /* Put devices to sleep */
 292                 error = device_suspend(PMSG_SUSPEND);
 293                 if (error) {
 294                         printk(KERN_ERR "Failed to suspend some devices.\n");
 295                 } else {
 296                         /* Enter S3, system is already frozen */
 297                         suspend_enter(PM_SUSPEND_MEM);
 298
 299                         /* Wake up devices */
 300                         device_resume();
 301                 }
 302
 303                 if (pm_ops->finish)
 304                         pm_ops->finish(PM_SUSPEND_MEM);
 305
 306 OutS3:
 307                 up(&pm_sem);
 308                 break;
 309
 310         default:
 311                 error = -ENOTTY;
 312
 313         }
 314
 315         return error;
 316 }
 317
 318 static struct file_operations snapshot_fops = {
 319         .open = snapshot_open,
 320         .release = snapshot_release,
 321         .read = snapshot_read,
 322         .write = snapshot_write,
 323         .llseek = no_llseek,
 324         .ioctl = snapshot_ioctl,
 325 };
 326
 327 static struct miscdevice snapshot_device = {
 328         .minor = SNAPSHOT_MINOR,
 329         .name = "snapshot",
 330         .fops = &snapshot_fops,
 331 };
 332
 333 static int __init snapshot_device_init(void)
 334 {
 335         return misc_register(&snapshot_device);
 336 };
 337
 338 device_initcall(snapshot_device_init);