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 unsigned int result = 0; 73 74 if (!clk) 75 return POLLERR; 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 }; 447