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/file.h>
  22 #include <linux/mutex.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         mutex_lock(&clk->mutex);
  38
  39         if (!clk->zombie)
  40                 return clk;
  41
  42         mutex_unlock(&clk->mutex);
  43
  44         return NULL;
  45 }
  46
  47 static void put_posix_clock(struct posix_clock *clk)
  48 {
  49         mutex_unlock(&clk->mutex);
  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         mutex_lock(&clk->mutex);
 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         mutex_unlock(&clk->mutex);
 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         mutex_init(&clk->mutex);
 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         if (err)
 220                 goto no_cdev;
 221
 222         return err;
 223 no_cdev:
 224         mutex_destroy(&clk->mutex);
 225         return err;
 226 }
 227 EXPORT_SYMBOL_GPL(posix_clock_register);
 228
 229 static void delete_clock(struct kref *kref)
 230 {
 231         struct posix_clock *clk = container_of(kref, struct posix_clock, kref);
 232         mutex_destroy(&clk->mutex);
 233         if (clk->release)
 234                 clk->release(clk);
 235 }
 236
 237 void posix_clock_unregister(struct posix_clock *clk)
 238 {
 239         cdev_del(&clk->cdev);
 240
 241         mutex_lock(&clk->mutex);
 242         clk->zombie = true;
 243         mutex_unlock(&clk->mutex);
 244
 245         kref_put(&clk->kref, delete_clock);
 246 }
 247 EXPORT_SYMBOL_GPL(posix_clock_unregister);
 248
 249 struct posix_clock_desc {
 250         struct file *fp;
 251         struct posix_clock *clk;
 252 };
 253
 254 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
 255 {
 256         struct file *fp = fget(CLOCKID_TO_FD(id));
 257         int err = -EINVAL;
 258
 259         if (!fp)
 260                 return err;
 261
 262         if (fp->f_op->open != posix_clock_open || !fp->private_data)
 263                 goto out;
 264
 265         cd->fp = fp;
 266         cd->clk = get_posix_clock(fp);
 267
 268         err = cd->clk ? 0 : -ENODEV;
 269 out:
 270         if (err)
 271                 fput(fp);
 272         return err;
 273 }
 274
 275 static void put_clock_desc(struct posix_clock_desc *cd)
 276 {
 277         put_posix_clock(cd->clk);
 278         fput(cd->fp);
 279 }
 280
 281 static int pc_clock_adjtime(clockid_t id, struct timex *tx)
 282 {
 283         struct posix_clock_desc cd;
 284         int err;
 285
 286         err = get_clock_desc(id, &cd);
 287         if (err)
 288                 return err;
 289
 290         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
 291                 err = -EACCES;
 292                 goto out;
 293         }
 294
 295         if (cd.clk->ops.clock_adjtime)
 296                 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
 297         else
 298                 err = -EOPNOTSUPP;
 299 out:
 300         put_clock_desc(&cd);
 301
 302         return err;
 303 }
 304
 305 static int pc_clock_gettime(clockid_t id, struct timespec *ts)
 306 {
 307         struct posix_clock_desc cd;
 308         int err;
 309
 310         err = get_clock_desc(id, &cd);
 311         if (err)
 312                 return err;
 313
 314         if (cd.clk->ops.clock_gettime)
 315                 err = cd.clk->ops.clock_gettime(cd.clk, ts);
 316         else
 317                 err = -EOPNOTSUPP;
 318
 319         put_clock_desc(&cd);
 320
 321         return err;
 322 }
 323
 324 static int pc_clock_getres(clockid_t id, struct timespec *ts)
 325 {
 326         struct posix_clock_desc cd;
 327         int err;
 328
 329         err = get_clock_desc(id, &cd);
 330         if (err)
 331                 return err;
 332
 333         if (cd.clk->ops.clock_getres)
 334                 err = cd.clk->ops.clock_getres(cd.clk, ts);
 335         else
 336                 err = -EOPNOTSUPP;
 337
 338         put_clock_desc(&cd);
 339
 340         return err;
 341 }
 342
 343 static int pc_clock_settime(clockid_t id, const struct timespec *ts)
 344 {
 345         struct posix_clock_desc cd;
 346         int err;
 347
 348         err = get_clock_desc(id, &cd);
 349         if (err)
 350                 return err;
 351
 352         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
 353                 err = -EACCES;
 354                 goto out;
 355         }
 356
 357         if (cd.clk->ops.clock_settime)
 358                 err = cd.clk->ops.clock_settime(cd.clk, ts);
 359         else
 360                 err = -EOPNOTSUPP;
 361 out:
 362         put_clock_desc(&cd);
 363
 364         return err;
 365 }
 366
 367 static int pc_timer_create(struct k_itimer *kit)
 368 {
 369         clockid_t id = kit->it_clock;
 370         struct posix_clock_desc cd;
 371         int err;
 372
 373         err = get_clock_desc(id, &cd);
 374         if (err)
 375                 return err;
 376
 377         if (cd.clk->ops.timer_create)
 378                 err = cd.clk->ops.timer_create(cd.clk, kit);
 379         else
 380                 err = -EOPNOTSUPP;
 381
 382         put_clock_desc(&cd);
 383
 384         return err;
 385 }
 386
 387 static int pc_timer_delete(struct k_itimer *kit)
 388 {
 389         clockid_t id = kit->it_clock;
 390         struct posix_clock_desc cd;
 391         int err;
 392
 393         err = get_clock_desc(id, &cd);
 394         if (err)
 395                 return err;
 396
 397         if (cd.clk->ops.timer_delete)
 398                 err = cd.clk->ops.timer_delete(cd.clk, kit);
 399         else
 400                 err = -EOPNOTSUPP;
 401
 402         put_clock_desc(&cd);
 403
 404         return err;
 405 }
 406
 407 static void pc_timer_gettime(struct k_itimer *kit, struct itimerspec *ts)
 408 {
 409         clockid_t id = kit->it_clock;
 410         struct posix_clock_desc cd;
 411
 412         if (get_clock_desc(id, &cd))
 413                 return;
 414
 415         if (cd.clk->ops.timer_gettime)
 416                 cd.clk->ops.timer_gettime(cd.clk, kit, ts);
 417
 418         put_clock_desc(&cd);
 419 }
 420
 421 static int pc_timer_settime(struct k_itimer *kit, int flags,
 422                             struct itimerspec *ts, struct itimerspec *old)
 423 {
 424         clockid_t id = kit->it_clock;
 425         struct posix_clock_desc cd;
 426         int err;
 427
 428         err = get_clock_desc(id, &cd);
 429         if (err)
 430                 return err;
 431
 432         if (cd.clk->ops.timer_settime)
 433                 err = cd.clk->ops.timer_settime(cd.clk, kit, flags, ts, old);
 434         else
 435                 err = -EOPNOTSUPP;
 436
 437         put_clock_desc(&cd);
 438
 439         return err;
 440 }
 441
 442 struct k_clock clock_posix_dynamic = {
 443         .clock_getres   = pc_clock_getres,
 444         .clock_set      = pc_clock_settime,
 445         .clock_get      = pc_clock_gettime,
 446         .clock_adj      = pc_clock_adjtime,
 447         .timer_create   = pc_timer_create,
 448         .timer_set      = pc_timer_settime,
 449         .timer_del      = pc_timer_delete,
 450         .timer_get      = pc_timer_gettime,
 451 };