kernel/time/posix-clock.c

   1 /*
   2  * posix-clock.c - support for dynamic clock devices
   3  *
   4  * Copyright (C) 2010 OMICRON electronics GmbH
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20 #include <linux/device.h>
  21 #include <linux/export.h>
  22 #include <linux/file.h>
  23 #include <linux/posix-clock.h>
  24 #include <linux/slab.h>
  25 #include <linux/syscalls.h>
  26 #include <linux/uaccess.h>
  27
  28 static void delete_clock(struct kref *kref);
  29
  30 /*
  31  * Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
  32  */
  33 static struct posix_clock *get_posix_clock(struct file *fp)
  34 {
  35         struct posix_clock *clk = fp->private_data;
  36
  37         down_read(&clk->rwsem);
  38
  39         if (!clk->zombie)
  40                 return clk;
  41
  42         up_read(&clk->rwsem);
  43
  44         return NULL;
  45 }
  46
  47 static void put_posix_clock(struct posix_clock *clk)
  48 {
  49         up_read(&clk->rwsem);
  50 }
  51
  52 static ssize_t posix_clock_read(struct file *fp, char __user *buf,
  53                                 size_t count, loff_t *ppos)
  54 {
  55         struct posix_clock *clk = get_posix_clock(fp);
  56         int err = -EINVAL;
  57
  58         if (!clk)
  59                 return -ENODEV;
  60
  61         if (clk->ops.read)
  62                 err = clk->ops.read(clk, fp->f_flags, buf, count);
  63
  64         put_posix_clock(clk);
  65
  66         return err;
  67 }
  68
  69 static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
  70 {
  71         struct posix_clock *clk = get_posix_clock(fp);
  72         int result = 0;
  73
  74         if (!clk)
  75                 return -ENODEV;
  76
  77         if (clk->ops.poll)
  78                 result = clk->ops.poll(clk, fp, wait);
  79
  80         put_posix_clock(clk);
  81
  82         return result;
  83 }
  84
  85 static int posix_clock_fasync(int fd, struct file *fp, int on)
  86 {
  87         struct posix_clock *clk = get_posix_clock(fp);
  88         int err = 0;
  89
  90         if (!clk)
  91                 return -ENODEV;
  92
  93         if (clk->ops.fasync)
  94                 err = clk->ops.fasync(clk, fd, fp, on);
  95
  96         put_posix_clock(clk);
  97
  98         return err;
  99 }
 100
 101 static int posix_clock_mmap(struct file *fp, struct vm_area_struct *vma)
 102 {
 103         struct posix_clock *clk = get_posix_clock(fp);
 104         int err = -ENODEV;
 105
 106         if (!clk)
 107                 return -ENODEV;
 108
 109         if (clk->ops.mmap)
 110                 err = clk->ops.mmap(clk, vma);
 111
 112         put_posix_clock(clk);
 113
 114         return err;
 115 }
 116
 117 static long posix_clock_ioctl(struct file *fp,
 118                               unsigned int cmd, unsigned long arg)
 119 {
 120         struct posix_clock *clk = get_posix_clock(fp);
 121         int err = -ENOTTY;
 122
 123         if (!clk)
 124                 return -ENODEV;
 125
 126         if (clk->ops.ioctl)
 127                 err = clk->ops.ioctl(clk, cmd, arg);
 128
 129         put_posix_clock(clk);
 130
 131         return err;
 132 }
 133
 134 #ifdef CONFIG_COMPAT
 135 static long posix_clock_compat_ioctl(struct file *fp,
 136                                      unsigned int cmd, unsigned long arg)
 137 {
 138         struct posix_clock *clk = get_posix_clock(fp);
 139         int err = -ENOTTY;
 140
 141         if (!clk)
 142                 return -ENODEV;
 143
 144         if (clk->ops.ioctl)
 145                 err = clk->ops.ioctl(clk, cmd, arg);
 146
 147         put_posix_clock(clk);
 148
 149         return err;
 150 }
 151 #endif
 152
 153 static int posix_clock_open(struct inode *inode, struct file *fp)
 154 {
 155         int err;
 156         struct posix_clock *clk =
 157                 container_of(inode->i_cdev, struct posix_clock, cdev);
 158
 159         down_read(&clk->rwsem);
 160
 161         if (clk->zombie) {
 162                 err = -ENODEV;
 163                 goto out;
 164         }
 165         if (clk->ops.open)
 166                 err = clk->ops.open(clk, fp->f_mode);
 167         else
 168                 err = 0;
 169
 170         if (!err) {
 171                 kref_get(&clk->kref);
 172                 fp->private_data = clk;
 173         }
 174 out:
 175         up_read(&clk->rwsem);
 176         return err;
 177 }
 178
 179 static int posix_clock_release(struct inode *inode, struct file *fp)
 180 {
 181         struct posix_clock *clk = fp->private_data;
 182         int err = 0;
 183
 184         if (clk->ops.release)
 185                 err = clk->ops.release(clk);
 186
 187         kref_put(&clk->kref, delete_clock);
 188
 189         fp->private_data = NULL;
 190
 191         return err;
 192 }
 193
 194 static const struct file_operations posix_clock_file_operations = {
 195         .owner          = THIS_MODULE,
 196         .llseek         = no_llseek,
 197         .read           = posix_clock_read,
 198         .poll           = posix_clock_poll,
 199         .unlocked_ioctl = posix_clock_ioctl,
 200         .open           = posix_clock_open,
 201         .release        = posix_clock_release,
 202         .fasync         = posix_clock_fasync,
 203         .mmap           = posix_clock_mmap,
 204 #ifdef CONFIG_COMPAT
 205         .compat_ioctl   = posix_clock_compat_ioctl,
 206 #endif
 207 };
 208
 209 int posix_clock_register(struct posix_clock *clk, dev_t devid)
 210 {
 211         int err;
 212
 213         kref_init(&clk->kref);
 214         init_rwsem(&clk->rwsem);
 215
 216         cdev_init(&clk->cdev, &posix_clock_file_operations);
 217         clk->cdev.owner = clk->ops.owner;
 218         err = cdev_add(&clk->cdev, devid, 1);
 219
 220         return err;
 221 }
 222 EXPORT_SYMBOL_GPL(posix_clock_register);
 223
 224 static void delete_clock(struct kref *kref)
 225 {
 226         struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
 227
 228         if (clk->release)
 229                 clk->release(clk);
 230 }
 231
 232 void posix_clock_unregister(struct posix_clock *clk)
 233 {
 234         cdev_del(&clk->cdev);
 235
 236         down_write(&clk->rwsem);
 237         clk->zombie = true;
 238         up_write(&clk->rwsem);
 239
 240         kref_put(&clk->kref, delete_clock);
 241 }
 242 EXPORT_SYMBOL_GPL(posix_clock_unregister);
 243
 244 struct posix_clock_desc {
 245         struct file *fp;
 246         struct posix_clock *clk;
 247 };
 248
 249 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
 250 {
 251         struct file *fp = fget(CLOCKID_TO_FD(id));
 252         int err = -EINVAL;
 253
 254         if (!fp)
 255                 return err;
 256
 257         if (fp->f_op->open != posix_clock_open || !fp->private_data)
 258                 goto out;
 259
 260         cd->fp = fp;
 261         cd->clk = get_posix_clock(fp);
 262
 263         err = cd->clk ? 0 : -ENODEV;
 264 out:
 265         if (err)
 266                 fput(fp);
 267         return err;
 268 }
 269
 270 static void put_clock_desc(struct posix_clock_desc *cd)
 271 {
 272         put_posix_clock(cd->clk);
 273         fput(cd->fp);
 274 }
 275
 276 static int pc_clock_adjtime(clockid_t id, struct timex *tx)
 277 {
 278         struct posix_clock_desc cd;
 279         int err;
 280
 281         err = get_clock_desc(id, &cd);
 282         if (err)
 283                 return err;
 284
 285         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
 286                 err = -EACCES;
 287                 goto out;
 288         }
 289
 290         if (cd.clk->ops.clock_adjtime)
 291                 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
 292         else
 293                 err = -EOPNOTSUPP;
 294 out:
 295         put_clock_desc(&cd);
 296
 297         return err;
 298 }
 299
 300 static int pc_clock_gettime(clockid_t id, struct timespec *ts)
 301 {
 302         struct posix_clock_desc cd;
 303         int err;
 304
 305         err = get_clock_desc(id, &cd);
 306         if (err)
 307                 return err;
 308
 309         if (cd.clk->ops.clock_gettime)
 310                 err = cd.clk->ops.clock_gettime(cd.clk, ts);
 311         else
 312                 err = -EOPNOTSUPP;
 313
 314         put_clock_desc(&cd);
 315
 316         return err;
 317 }
 318
 319 static int pc_clock_getres(clockid_t id, struct timespec *ts)
 320 {
 321         struct posix_clock_desc cd;
 322         int err;
 323
 324         err = get_clock_desc(id, &cd);
 325         if (err)
 326                 return err;
 327
 328         if (cd.clk->ops.clock_getres)
 329                 err = cd.clk->ops.clock_getres(cd.clk, ts);
 330         else
 331                 err = -EOPNOTSUPP;
 332
 333         put_clock_desc(&cd);
 334
 335         return err;
 336 }
 337
 338 static int pc_clock_settime(clockid_t id, const struct timespec *ts)
 339 {
 340         struct posix_clock_desc cd;
 341         int err;
 342
 343         err = get_clock_desc(id, &cd);
 344         if (err)
 345                 return err;
 346
 347         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
 348                 err = -EACCES;
 349                 goto out;
 350         }
 351
 352         if (cd.clk->ops.clock_settime)
 353                 err = cd.clk->ops.clock_settime(cd.clk, ts);
 354         else
 355                 err = -EOPNOTSUPP;
 356 out:
 357         put_clock_desc(&cd);
 358
 359         return err;
 360 }
 361
 362 static int pc_timer_create(struct k_itimer *kit)
 363 {
 364         clockid_t id = kit->it_clock;
 365         struct posix_clock_desc cd;
 366         int err;
 367
 368         err = get_clock_desc(id, &cd);
 369         if (err)
 370                 return err;
 371
 372         if (cd.clk->ops.timer_create)
 373                 err = cd.clk->ops.timer_create(cd.clk, kit);
 374         else
 375                 err = -EOPNOTSUPP;
 376
 377         put_clock_desc(&cd);
 378
 379         return err;
 380 }
 381
 382 static int pc_timer_delete(struct k_itimer *kit)
 383 {
 384         clockid_t id = kit->it_clock;
 385         struct posix_clock_desc cd;
 386         int err;
 387
 388         err = get_clock_desc(id, &cd);
 389         if (err)
 390                 return err;
 391
 392         if (cd.clk->ops.timer_delete)
 393                 err = cd.clk->ops.timer_delete(cd.clk, kit);
 394         else
 395                 err = -EOPNOTSUPP;
 396
 397         put_clock_desc(&cd);
 398
 399         return err;
 400 }
 401
 402 static void pc_timer_gettime(struct k_itimer *kit, struct itimerspec *ts)
 403 {
 404         clockid_t id = kit->it_clock;
 405         struct posix_clock_desc cd;
 406
 407         if (get_clock_desc(id, &cd))
 408                 return;
 409
 410         if (cd.clk->ops.timer_gettime)
 411                 cd.clk->ops.timer_gettime(cd.clk, kit, ts);
 412
 413         put_clock_desc(&cd);
 414 }
 415
 416 static int pc_timer_settime(struct k_itimer *kit, int flags,
 417                             struct itimerspec *ts, struct itimerspec *old)
 418 {
 419         clockid_t id = kit->it_clock;
 420         struct posix_clock_desc cd;
 421         int err;
 422
 423         err = get_clock_desc(id, &cd);
 424         if (err)
 425                 return err;
 426
 427         if (cd.clk->ops.timer_settime)
 428                 err = cd.clk->ops.timer_settime(cd.clk, kit, flags, ts, old);
 429         else
 430                 err = -EOPNOTSUPP;
 431
 432         put_clock_desc(&cd);
 433
 434         return err;
 435 }
 436
 437 struct k_clock clock_posix_dynamic = {
 438         .clock_getres   = pc_clock_getres,
 439         .clock_set      = pc_clock_settime,
 440         .clock_get      = pc_clock_gettime,
 441         .clock_adj      = pc_clock_adjtime,
 442         .timer_create   = pc_timer_create,
 443         .timer_set      = pc_timer_settime,
 444         .timer_del      = pc_timer_delete,
 445         .timer_get      = pc_timer_gettime,
 446 };