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 #include "posix-timers.h" 29 30 static void delete_clock(struct kref *kref); 31 32 /* 33 * Returns NULL if the posix_clock instance attached to 'fp' is old and stale. 34 */ 35 static struct posix_clock *get_posix_clock(struct file *fp) 36 { 37 struct posix_clock *clk = fp->private_data; 38 39 down_read(&clk->rwsem); 40 41 if (!clk->zombie) 42 return clk; 43 44 up_read(&clk->rwsem); 45 46 return NULL; 47 } 48 49 static void put_posix_clock(struct posix_clock *clk) 50 { 51 up_read(&clk->rwsem); 52 } 53 54 static ssize_t posix_clock_read(struct file *fp, char __user *buf, 55 size_t count, loff_t *ppos) 56 { 57 struct posix_clock *clk = get_posix_clock(fp); 58 int err = -EINVAL; 59 60 if (!clk) 61 return -ENODEV; 62 63 if (clk->ops.read) 64 err = clk->ops.read(clk, fp->f_flags, buf, count); 65 66 put_posix_clock(clk); 67 68 return err; 69 } 70 71 static __poll_t posix_clock_poll(struct file *fp, poll_table *wait) 72 { 73 struct posix_clock *clk = get_posix_clock(fp); 74 __poll_t result = 0; 75 76 if (!clk) 77 return EPOLLERR; 78 79 if (clk->ops.poll) 80 result = clk->ops.poll(clk, fp, wait); 81 82 put_posix_clock(clk); 83 84 return result; 85 } 86 87 static long posix_clock_ioctl(struct file *fp, 88 unsigned int cmd, unsigned long arg) 89 { 90 struct posix_clock *clk = get_posix_clock(fp); 91 int err = -ENOTTY; 92 93 if (!clk) 94 return -ENODEV; 95 96 if (clk->ops.ioctl) 97 err = clk->ops.ioctl(clk, cmd, arg); 98 99 put_posix_clock(clk); 100 101 return err; 102 } 103 104 #ifdef CONFIG_COMPAT 105 static long posix_clock_compat_ioctl(struct file *fp, 106 unsigned int cmd, unsigned long arg) 107 { 108 struct posix_clock *clk = get_posix_clock(fp); 109 int err = -ENOTTY; 110 111 if (!clk) 112 return -ENODEV; 113 114 if (clk->ops.ioctl) 115 err = clk->ops.ioctl(clk, cmd, arg); 116 117 put_posix_clock(clk); 118 119 return err; 120 } 121 #endif 122 123 static int posix_clock_open(struct inode *inode, struct file *fp) 124 { 125 int err; 126 struct posix_clock *clk = 127 container_of(inode->i_cdev, struct posix_clock, cdev); 128 129 down_read(&clk->rwsem); 130 131 if (clk->zombie) { 132 err = -ENODEV; 133 goto out; 134 } 135 if (clk->ops.open) 136 err = clk->ops.open(clk, fp->f_mode); 137 else 138 err = 0; 139 140 if (!err) { 141 kref_get(&clk->kref); 142 fp->private_data = clk; 143 } 144 out: 145 up_read(&clk->rwsem); 146 return err; 147 } 148 149 static int posix_clock_release(struct inode *inode, struct file *fp) 150 { 151 struct posix_clock *clk = fp->private_data; 152 int err = 0; 153 154 if (clk->ops.release) 155 err = clk->ops.release(clk); 156 157 kref_put(&clk->kref, delete_clock); 158 159 fp->private_data = NULL; 160 161 return err; 162 } 163 164 static const struct file_operations posix_clock_file_operations = { 165 .owner = THIS_MODULE, 166 .llseek = no_llseek, 167 .read = posix_clock_read, 168 .poll = posix_clock_poll, 169 .unlocked_ioctl = posix_clock_ioctl, 170 .open = posix_clock_open, 171 .release = posix_clock_release, 172 #ifdef CONFIG_COMPAT 173 .compat_ioctl = posix_clock_compat_ioctl, 174 #endif 175 }; 176 177 int posix_clock_register(struct posix_clock *clk, dev_t devid) 178 { 179 int err; 180 181 kref_init(&clk->kref); 182 init_rwsem(&clk->rwsem); 183 184 cdev_init(&clk->cdev, &posix_clock_file_operations); 185 clk->cdev.owner = clk->ops.owner; 186 err = cdev_add(&clk->cdev, devid, 1); 187 188 return err; 189 } 190 EXPORT_SYMBOL_GPL(posix_clock_register); 191 192 static void delete_clock(struct kref *kref) 193 { 194 struct posix_clock *clk = container_of(kref, struct posix_clock, kref); 195 196 if (clk->release) 197 clk->release(clk); 198 } 199 200 void posix_clock_unregister(struct posix_clock *clk) 201 { 202 cdev_del(&clk->cdev); 203 204 down_write(&clk->rwsem); 205 clk->zombie = true; 206 up_write(&clk->rwsem); 207 208 kref_put(&clk->kref, delete_clock); 209 } 210 EXPORT_SYMBOL_GPL(posix_clock_unregister); 211 212 struct posix_clock_desc { 213 struct file *fp; 214 struct posix_clock *clk; 215 }; 216 217 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd) 218 { 219 struct file *fp = fget(clockid_to_fd(id)); 220 int err = -EINVAL; 221 222 if (!fp) 223 return err; 224 225 if (fp->f_op->open != posix_clock_open || !fp->private_data) 226 goto out; 227 228 cd->fp = fp; 229 cd->clk = get_posix_clock(fp); 230 231 err = cd->clk ? 0 : -ENODEV; 232 out: 233 if (err) 234 fput(fp); 235 return err; 236 } 237 238 static void put_clock_desc(struct posix_clock_desc *cd) 239 { 240 put_posix_clock(cd->clk); 241 fput(cd->fp); 242 } 243 244 static int pc_clock_adjtime(clockid_t id, struct timex *tx) 245 { 246 struct posix_clock_desc cd; 247 int err; 248 249 err = get_clock_desc(id, &cd); 250 if (err) 251 return err; 252 253 if ((cd.fp->f_mode & FMODE_WRITE) == 0) { 254 err = -EACCES; 255 goto out; 256 } 257 258 if (cd.clk->ops.clock_adjtime) 259 err = cd.clk->ops.clock_adjtime(cd.clk, tx); 260 else 261 err = -EOPNOTSUPP; 262 out: 263 put_clock_desc(&cd); 264 265 return err; 266 } 267 268 static int pc_clock_gettime(clockid_t id, struct timespec64 *ts) 269 { 270 struct posix_clock_desc cd; 271 int err; 272 273 err = get_clock_desc(id, &cd); 274 if (err) 275 return err; 276 277 if (cd.clk->ops.clock_gettime) 278 err = cd.clk->ops.clock_gettime(cd.clk, ts); 279 else 280 err = -EOPNOTSUPP; 281 282 put_clock_desc(&cd); 283 284 return err; 285 } 286 287 static int pc_clock_getres(clockid_t id, struct timespec64 *ts) 288 { 289 struct posix_clock_desc cd; 290 int err; 291 292 err = get_clock_desc(id, &cd); 293 if (err) 294 return err; 295 296 if (cd.clk->ops.clock_getres) 297 err = cd.clk->ops.clock_getres(cd.clk, ts); 298 else 299 err = -EOPNOTSUPP; 300 301 put_clock_desc(&cd); 302 303 return err; 304 } 305 306 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts) 307 { 308 struct posix_clock_desc cd; 309 int err; 310 311 err = get_clock_desc(id, &cd); 312 if (err) 313 return err; 314 315 if ((cd.fp->f_mode & FMODE_WRITE) == 0) { 316 err = -EACCES; 317 goto out; 318 } 319 320 if (cd.clk->ops.clock_settime) 321 err = cd.clk->ops.clock_settime(cd.clk, ts); 322 else 323 err = -EOPNOTSUPP; 324 out: 325 put_clock_desc(&cd); 326 327 return err; 328 } 329 330 const struct k_clock clock_posix_dynamic = { 331 .clock_getres = pc_clock_getres, 332 .clock_set = pc_clock_settime, 333 .clock_get = pc_clock_gettime, 334 .clock_adj = pc_clock_adjtime, 335 }; 336