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 /*
  29  * Returns NULL if the posix_clock instance attached to 'fp' is old and stale.
  30  */
  31 static struct posix_clock *get_posix_clock(struct file *fp)
  32 {
  33         struct posix_clock *clk = fp->private_data;
  34
  35         down_read(&clk->rwsem);
  36
  37         if (!clk->zombie)
  38                 return clk;
  39
  40         up_read(&clk->rwsem);
  41
  42         return NULL;
  43 }
  44
  45 static void put_posix_clock(struct posix_clock *clk)
  46 {
  47         up_read(&clk->rwsem);
  48 }
  49
  50 static ssize_t posix_clock_read(struct file *fp, char __user *buf,
  51                                 size_t count, loff_t *ppos)
  52 {
  53         struct posix_clock *clk = get_posix_clock(fp);
  54         int err = -EINVAL;
  55
  56         if (!clk)
  57                 return -ENODEV;
  58
  59         if (clk->ops.read)
  60                 err = clk->ops.read(clk, fp->f_flags, buf, count);
  61
  62         put_posix_clock(clk);
  63
  64         return err;
  65 }
  66
  67 static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
  68 {
  69         struct posix_clock *clk = get_posix_clock(fp);
  70         unsigned int result = 0;
  71
  72         if (!clk)
  73                 return POLLERR;
  74
  75         if (clk->ops.poll)
  76                 result = clk->ops.poll(clk, fp, wait);
  77
  78         put_posix_clock(clk);
  79
  80         return result;
  81 }
  82
  83 static int posix_clock_fasync(int fd, struct file *fp, int on)
  84 {
  85         struct posix_clock *clk = get_posix_clock(fp);
  86         int err = 0;
  87
  88         if (!clk)
  89                 return -ENODEV;
  90
  91         if (clk->ops.fasync)
  92                 err = clk->ops.fasync(clk, fd, fp, on);
  93
  94         put_posix_clock(clk);
  95
  96         return err;
  97 }
  98
  99 static int posix_clock_mmap(struct file *fp, struct vm_area_struct *vma)
 100 {
 101         struct posix_clock *clk = get_posix_clock(fp);
 102         int err = -ENODEV;
 103
 104         if (!clk)
 105                 return -ENODEV;
 106
 107         if (clk->ops.mmap)
 108                 err = clk->ops.mmap(clk, vma);
 109
 110         put_posix_clock(clk);
 111
 112         return err;
 113 }
 114
 115 static long posix_clock_ioctl(struct file *fp,
 116                               unsigned int cmd, unsigned long arg)
 117 {
 118         struct posix_clock *clk = get_posix_clock(fp);
 119         int err = -ENOTTY;
 120
 121         if (!clk)
 122                 return -ENODEV;
 123
 124         if (clk->ops.ioctl)
 125                 err = clk->ops.ioctl(clk, cmd, arg);
 126
 127         put_posix_clock(clk);
 128
 129         return err;
 130 }
 131
 132 #ifdef CONFIG_COMPAT
 133 static long posix_clock_compat_ioctl(struct file *fp,
 134                                      unsigned int cmd, unsigned long arg)
 135 {
 136         struct posix_clock *clk = get_posix_clock(fp);
 137         int err = -ENOTTY;
 138
 139         if (!clk)
 140                 return -ENODEV;
 141
 142         if (clk->ops.ioctl)
 143                 err = clk->ops.ioctl(clk, cmd, arg);
 144
 145         put_posix_clock(clk);
 146
 147         return err;
 148 }
 149 #endif
 150
 151 static int posix_clock_open(struct inode *inode, struct file *fp)
 152 {
 153         int err;
 154         struct posix_clock *clk =
 155                 container_of(inode->i_cdev, struct posix_clock, cdev);
 156
 157         down_read(&clk->rwsem);
 158
 159         if (clk->zombie) {
 160                 err = -ENODEV;
 161                 goto out;
 162         }
 163         if (clk->ops.open)
 164                 err = clk->ops.open(clk, fp->f_mode);
 165         else
 166                 err = 0;
 167
 168         if (!err) {
 169                 get_device(clk->dev);
 170                 fp->private_data = clk;
 171         }
 172 out:
 173         up_read(&clk->rwsem);
 174         return err;
 175 }
 176
 177 static int posix_clock_release(struct inode *inode, struct file *fp)
 178 {
 179         struct posix_clock *clk = fp->private_data;
 180         int err = 0;
 181
 182         if (clk->ops.release)
 183                 err = clk->ops.release(clk);
 184
 185         put_device(clk->dev);
 186
 187         fp->private_data = NULL;
 188
 189         return err;
 190 }
 191
 192 static const struct file_operations posix_clock_file_operations = {
 193         .owner          = THIS_MODULE,
 194         .llseek         = no_llseek,
 195         .read           = posix_clock_read,
 196         .poll           = posix_clock_poll,
 197         .unlocked_ioctl = posix_clock_ioctl,
 198         .open           = posix_clock_open,
 199         .release        = posix_clock_release,
 200         .fasync         = posix_clock_fasync,
 201         .mmap           = posix_clock_mmap,
 202 #ifdef CONFIG_COMPAT
 203         .compat_ioctl   = posix_clock_compat_ioctl,
 204 #endif
 205 };
 206
 207 int posix_clock_register(struct posix_clock *clk, struct device *dev)
 208 {
 209         int err;
 210
 211         init_rwsem(&clk->rwsem);
 212
 213         cdev_init(&clk->cdev, &posix_clock_file_operations);
 214         err = cdev_device_add(&clk->cdev, dev);
 215         if (err) {
 216                 pr_err("%s unable to add device %d:%d\n",
 217                         dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt));
 218                 return err;
 219         }
 220         clk->cdev.owner = clk->ops.owner;
 221         clk->dev = dev;
 222
 223         return 0;
 224 }
 225 EXPORT_SYMBOL_GPL(posix_clock_register);
 226
 227 void posix_clock_unregister(struct posix_clock *clk)
 228 {
 229         cdev_device_del(&clk->cdev, clk->dev);
 230
 231         down_write(&clk->rwsem);
 232         clk->zombie = true;
 233         up_write(&clk->rwsem);
 234
 235         put_device(clk->dev);
 236 }
 237 EXPORT_SYMBOL_GPL(posix_clock_unregister);
 238
 239 struct posix_clock_desc {
 240         struct file *fp;
 241         struct posix_clock *clk;
 242 };
 243
 244 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
 245 {
 246         struct file *fp = fget(CLOCKID_TO_FD(id));
 247         int err = -EINVAL;
 248
 249         if (!fp)
 250                 return err;
 251
 252         if (fp->f_op->open != posix_clock_open || !fp->private_data)
 253                 goto out;
 254
 255         cd->fp = fp;
 256         cd->clk = get_posix_clock(fp);
 257
 258         err = cd->clk ? 0 : -ENODEV;
 259 out:
 260         if (err)
 261                 fput(fp);
 262         return err;
 263 }
 264
 265 static void put_clock_desc(struct posix_clock_desc *cd)
 266 {
 267         put_posix_clock(cd->clk);
 268         fput(cd->fp);
 269 }
 270
 271 static int pc_clock_adjtime(clockid_t id, struct timex *tx)
 272 {
 273         struct posix_clock_desc cd;
 274         int err;
 275
 276         err = get_clock_desc(id, &cd);
 277         if (err)
 278                 return err;
 279
 280         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
 281                 err = -EACCES;
 282                 goto out;
 283         }
 284
 285         if (cd.clk->ops.clock_adjtime)
 286                 err = cd.clk->ops.clock_adjtime(cd.clk, tx);
 287         else
 288                 err = -EOPNOTSUPP;
 289 out:
 290         put_clock_desc(&cd);
 291
 292         return err;
 293 }
 294
 295 static int pc_clock_gettime(clockid_t id, struct timespec *ts)
 296 {
 297         struct posix_clock_desc cd;
 298         struct timespec64 ts64;
 299         int err;
 300
 301         err = get_clock_desc(id, &cd);
 302         if (err)
 303                 return err;
 304
 305         if (cd.clk->ops.clock_gettime) {
 306                 err = cd.clk->ops.clock_gettime(cd.clk, &ts64);
 307                 *ts = timespec64_to_timespec(ts64);
 308         }
 309         else
 310                 err = -EOPNOTSUPP;
 311
 312         put_clock_desc(&cd);
 313
 314         return err;
 315 }
 316
 317 static int pc_clock_getres(clockid_t id, struct timespec *ts)
 318 {
 319         struct posix_clock_desc cd;
 320         struct timespec64 ts64;
 321         int err;
 322
 323         err = get_clock_desc(id, &cd);
 324         if (err)
 325                 return err;
 326
 327         if (cd.clk->ops.clock_getres) {
 328                 err = cd.clk->ops.clock_getres(cd.clk, &ts64);
 329                 *ts = timespec64_to_timespec(ts64);
 330         }
 331         else
 332                 err = -EOPNOTSUPP;
 333
 334         put_clock_desc(&cd);
 335
 336         return err;
 337 }
 338
 339 static int pc_clock_settime(clockid_t id, const struct timespec *ts)
 340 {
 341         struct timespec64 ts64 = timespec_to_timespec64(*ts);
 342         struct posix_clock_desc cd;
 343         int err;
 344
 345         err = get_clock_desc(id, &cd);
 346         if (err)
 347                 return err;
 348
 349         if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
 350                 err = -EACCES;
 351                 goto out;
 352         }
 353
 354         if (cd.clk->ops.clock_settime)
 355                 err = cd.clk->ops.clock_settime(cd.clk, &ts64);
 356         else
 357                 err = -EOPNOTSUPP;
 358 out:
 359         put_clock_desc(&cd);
 360
 361         return err;
 362 }
 363
 364 static int pc_timer_create(struct k_itimer *kit)
 365 {
 366         clockid_t id = kit->it_clock;
 367         struct posix_clock_desc cd;
 368         int err;
 369
 370         err = get_clock_desc(id, &cd);
 371         if (err)
 372                 return err;
 373
 374         if (cd.clk->ops.timer_create)
 375                 err = cd.clk->ops.timer_create(cd.clk, kit);
 376         else
 377                 err = -EOPNOTSUPP;
 378
 379         put_clock_desc(&cd);
 380
 381         return err;
 382 }
 383
 384 static int pc_timer_delete(struct k_itimer *kit)
 385 {
 386         clockid_t id = kit->it_clock;
 387         struct posix_clock_desc cd;
 388         int err;
 389
 390         err = get_clock_desc(id, &cd);
 391         if (err)
 392                 return err;
 393
 394         if (cd.clk->ops.timer_delete)
 395                 err = cd.clk->ops.timer_delete(cd.clk, kit);
 396         else
 397                 err = -EOPNOTSUPP;
 398
 399         put_clock_desc(&cd);
 400
 401         return err;
 402 }
 403
 404 static void pc_timer_gettime(struct k_itimer *kit, struct itimerspec *ts)
 405 {
 406         clockid_t id = kit->it_clock;
 407         struct posix_clock_desc cd;
 408         struct itimerspec64 ts64;
 409
 410         if (get_clock_desc(id, &cd))
 411                 return;
 412
 413         if (cd.clk->ops.timer_gettime) {
 414                 cd.clk->ops.timer_gettime(cd.clk, kit, &ts64);
 415                 *ts = itimerspec64_to_itimerspec(&ts64);
 416         }
 417         put_clock_desc(&cd);
 418 }
 419
 420 static int pc_timer_settime(struct k_itimer *kit, int flags,
 421                             struct itimerspec *ts, struct itimerspec *old)
 422 {
 423         struct itimerspec64 ts64 = itimerspec_to_itimerspec64(ts);
 424         clockid_t id = kit->it_clock;
 425         struct posix_clock_desc cd;
 426         struct itimerspec64 old64;
 427         int err;
 428
 429         err = get_clock_desc(id, &cd);
 430         if (err)
 431                 return err;
 432
 433         if (cd.clk->ops.timer_settime) {
 434                 err = cd.clk->ops.timer_settime(cd.clk, kit, flags, &ts64, &old64);
 435                 if (old)
 436                         *old = itimerspec64_to_itimerspec(&old64);
 437         }
 438         else
 439                 err = -EOPNOTSUPP;
 440
 441         put_clock_desc(&cd);
 442
 443         return err;
 444 }
 445
 446 struct k_clock clock_posix_dynamic = {
 447         .clock_getres   = pc_clock_getres,
 448         .clock_set      = pc_clock_settime,
 449         .clock_get      = pc_clock_gettime,
 450         .clock_adj      = pc_clock_adjtime,
 451         .timer_create   = pc_timer_create,
 452         .timer_set      = pc_timer_settime,
 453         .timer_del      = pc_timer_delete,
 454         .timer_get      = pc_timer_gettime,
 455 };