| 1 | // SPDX-License-Identifier: GPL-2.0+ |
| 2 | /* |
| 3 | * Support for dynamic clock devices |
| 4 | * |
| 5 | * Copyright (C) 2010 OMICRON electronics GmbH |
| 6 | */ |
| 7 | #include <linux/device.h> |
| 8 | #include <linux/export.h> |
| 9 | #include <linux/file.h> |
| 10 | #include <linux/posix-clock.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/syscalls.h> |
| 13 | #include <linux/uaccess.h> |
| 14 | |
| 15 | #include "posix-timers.h" |
| 16 | |
| 17 | /* |
| 18 | * Returns NULL if the posix_clock instance attached to 'fp' is old and stale. |
| 19 | */ |
| 20 | static struct posix_clock *get_posix_clock(struct file *fp) |
| 21 | { |
| 22 | struct posix_clock *clk = fp->private_data; |
| 23 | |
| 24 | down_read(&clk->rwsem); |
| 25 | |
| 26 | if (!clk->zombie) |
| 27 | return clk; |
| 28 | |
| 29 | up_read(&clk->rwsem); |
| 30 | |
| 31 | return NULL; |
| 32 | } |
| 33 | |
| 34 | static void put_posix_clock(struct posix_clock *clk) |
| 35 | { |
| 36 | up_read(&clk->rwsem); |
| 37 | } |
| 38 | |
| 39 | static ssize_t posix_clock_read(struct file *fp, char __user *buf, |
| 40 | size_t count, loff_t *ppos) |
| 41 | { |
| 42 | struct posix_clock *clk = get_posix_clock(fp); |
| 43 | int err = -EINVAL; |
| 44 | |
| 45 | if (!clk) |
| 46 | return -ENODEV; |
| 47 | |
| 48 | if (clk->ops.read) |
| 49 | err = clk->ops.read(clk, fp->f_flags, buf, count); |
| 50 | |
| 51 | put_posix_clock(clk); |
| 52 | |
| 53 | return err; |
| 54 | } |
| 55 | |
| 56 | static __poll_t posix_clock_poll(struct file *fp, poll_table *wait) |
| 57 | { |
| 58 | struct posix_clock *clk = get_posix_clock(fp); |
| 59 | __poll_t result = 0; |
| 60 | |
| 61 | if (!clk) |
| 62 | return EPOLLERR; |
| 63 | |
| 64 | if (clk->ops.poll) |
| 65 | result = clk->ops.poll(clk, fp, wait); |
| 66 | |
| 67 | put_posix_clock(clk); |
| 68 | |
| 69 | return result; |
| 70 | } |
| 71 | |
| 72 | static long posix_clock_ioctl(struct file *fp, |
| 73 | unsigned int cmd, unsigned long arg) |
| 74 | { |
| 75 | struct posix_clock *clk = get_posix_clock(fp); |
| 76 | int err = -ENOTTY; |
| 77 | |
| 78 | if (!clk) |
| 79 | return -ENODEV; |
| 80 | |
| 81 | if (clk->ops.ioctl) |
| 82 | err = clk->ops.ioctl(clk, cmd, arg); |
| 83 | |
| 84 | put_posix_clock(clk); |
| 85 | |
| 86 | return err; |
| 87 | } |
| 88 | |
| 89 | #ifdef CONFIG_COMPAT |
| 90 | static long posix_clock_compat_ioctl(struct file *fp, |
| 91 | unsigned int cmd, unsigned long arg) |
| 92 | { |
| 93 | struct posix_clock *clk = get_posix_clock(fp); |
| 94 | int err = -ENOTTY; |
| 95 | |
| 96 | if (!clk) |
| 97 | return -ENODEV; |
| 98 | |
| 99 | if (clk->ops.ioctl) |
| 100 | err = clk->ops.ioctl(clk, cmd, arg); |
| 101 | |
| 102 | put_posix_clock(clk); |
| 103 | |
| 104 | return err; |
| 105 | } |
| 106 | #endif |
| 107 | |
| 108 | static int posix_clock_open(struct inode *inode, struct file *fp) |
| 109 | { |
| 110 | int err; |
| 111 | struct posix_clock *clk = |
| 112 | container_of(inode->i_cdev, struct posix_clock, cdev); |
| 113 | |
| 114 | down_read(&clk->rwsem); |
| 115 | |
| 116 | if (clk->zombie) { |
| 117 | err = -ENODEV; |
| 118 | goto out; |
| 119 | } |
| 120 | if (clk->ops.open) |
| 121 | err = clk->ops.open(clk, fp->f_mode); |
| 122 | else |
| 123 | err = 0; |
| 124 | |
| 125 | if (!err) { |
| 126 | get_device(clk->dev); |
| 127 | fp->private_data = clk; |
| 128 | } |
| 129 | out: |
| 130 | up_read(&clk->rwsem); |
| 131 | return err; |
| 132 | } |
| 133 | |
| 134 | static int posix_clock_release(struct inode *inode, struct file *fp) |
| 135 | { |
| 136 | struct posix_clock *clk = fp->private_data; |
| 137 | int err = 0; |
| 138 | |
| 139 | if (clk->ops.release) |
| 140 | err = clk->ops.release(clk); |
| 141 | |
| 142 | put_device(clk->dev); |
| 143 | |
| 144 | fp->private_data = NULL; |
| 145 | |
| 146 | return err; |
| 147 | } |
| 148 | |
| 149 | static const struct file_operations posix_clock_file_operations = { |
| 150 | .owner = THIS_MODULE, |
| 151 | .llseek = no_llseek, |
| 152 | .read = posix_clock_read, |
| 153 | .poll = posix_clock_poll, |
| 154 | .unlocked_ioctl = posix_clock_ioctl, |
| 155 | .open = posix_clock_open, |
| 156 | .release = posix_clock_release, |
| 157 | #ifdef CONFIG_COMPAT |
| 158 | .compat_ioctl = posix_clock_compat_ioctl, |
| 159 | #endif |
| 160 | }; |
| 161 | |
| 162 | int posix_clock_register(struct posix_clock *clk, struct device *dev) |
| 163 | { |
| 164 | int err; |
| 165 | |
| 166 | init_rwsem(&clk->rwsem); |
| 167 | |
| 168 | cdev_init(&clk->cdev, &posix_clock_file_operations); |
| 169 | err = cdev_device_add(&clk->cdev, dev); |
| 170 | if (err) { |
| 171 | pr_err("%s unable to add device %d:%d\n", |
| 172 | dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt)); |
| 173 | return err; |
| 174 | } |
| 175 | clk->cdev.owner = clk->ops.owner; |
| 176 | clk->dev = dev; |
| 177 | |
| 178 | return 0; |
| 179 | } |
| 180 | EXPORT_SYMBOL_GPL(posix_clock_register); |
| 181 | |
| 182 | void posix_clock_unregister(struct posix_clock *clk) |
| 183 | { |
| 184 | cdev_device_del(&clk->cdev, clk->dev); |
| 185 | |
| 186 | down_write(&clk->rwsem); |
| 187 | clk->zombie = true; |
| 188 | up_write(&clk->rwsem); |
| 189 | |
| 190 | put_device(clk->dev); |
| 191 | } |
| 192 | EXPORT_SYMBOL_GPL(posix_clock_unregister); |
| 193 | |
| 194 | struct posix_clock_desc { |
| 195 | struct file *fp; |
| 196 | struct posix_clock *clk; |
| 197 | }; |
| 198 | |
| 199 | static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd) |
| 200 | { |
| 201 | struct file *fp = fget(clockid_to_fd(id)); |
| 202 | int err = -EINVAL; |
| 203 | |
| 204 | if (!fp) |
| 205 | return err; |
| 206 | |
| 207 | if (fp->f_op->open != posix_clock_open || !fp->private_data) |
| 208 | goto out; |
| 209 | |
| 210 | cd->fp = fp; |
| 211 | cd->clk = get_posix_clock(fp); |
| 212 | |
| 213 | err = cd->clk ? 0 : -ENODEV; |
| 214 | out: |
| 215 | if (err) |
| 216 | fput(fp); |
| 217 | return err; |
| 218 | } |
| 219 | |
| 220 | static void put_clock_desc(struct posix_clock_desc *cd) |
| 221 | { |
| 222 | put_posix_clock(cd->clk); |
| 223 | fput(cd->fp); |
| 224 | } |
| 225 | |
| 226 | static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx) |
| 227 | { |
| 228 | struct posix_clock_desc cd; |
| 229 | int err; |
| 230 | |
| 231 | err = get_clock_desc(id, &cd); |
| 232 | if (err) |
| 233 | return err; |
| 234 | |
| 235 | if ((cd.fp->f_mode & FMODE_WRITE) == 0) { |
| 236 | err = -EACCES; |
| 237 | goto out; |
| 238 | } |
| 239 | |
| 240 | if (cd.clk->ops.clock_adjtime) |
| 241 | err = cd.clk->ops.clock_adjtime(cd.clk, tx); |
| 242 | else |
| 243 | err = -EOPNOTSUPP; |
| 244 | out: |
| 245 | put_clock_desc(&cd); |
| 246 | |
| 247 | return err; |
| 248 | } |
| 249 | |
| 250 | static int pc_clock_gettime(clockid_t id, struct timespec64 *ts) |
| 251 | { |
| 252 | struct posix_clock_desc cd; |
| 253 | int err; |
| 254 | |
| 255 | err = get_clock_desc(id, &cd); |
| 256 | if (err) |
| 257 | return err; |
| 258 | |
| 259 | if (cd.clk->ops.clock_gettime) |
| 260 | err = cd.clk->ops.clock_gettime(cd.clk, ts); |
| 261 | else |
| 262 | err = -EOPNOTSUPP; |
| 263 | |
| 264 | put_clock_desc(&cd); |
| 265 | |
| 266 | return err; |
| 267 | } |
| 268 | |
| 269 | static int pc_clock_getres(clockid_t id, struct timespec64 *ts) |
| 270 | { |
| 271 | struct posix_clock_desc cd; |
| 272 | int err; |
| 273 | |
| 274 | err = get_clock_desc(id, &cd); |
| 275 | if (err) |
| 276 | return err; |
| 277 | |
| 278 | if (cd.clk->ops.clock_getres) |
| 279 | err = cd.clk->ops.clock_getres(cd.clk, ts); |
| 280 | else |
| 281 | err = -EOPNOTSUPP; |
| 282 | |
| 283 | put_clock_desc(&cd); |
| 284 | |
| 285 | return err; |
| 286 | } |
| 287 | |
| 288 | static int pc_clock_settime(clockid_t id, const struct timespec64 *ts) |
| 289 | { |
| 290 | struct posix_clock_desc cd; |
| 291 | int err; |
| 292 | |
| 293 | err = get_clock_desc(id, &cd); |
| 294 | if (err) |
| 295 | return err; |
| 296 | |
| 297 | if ((cd.fp->f_mode & FMODE_WRITE) == 0) { |
| 298 | err = -EACCES; |
| 299 | goto out; |
| 300 | } |
| 301 | |
| 302 | if (cd.clk->ops.clock_settime) |
| 303 | err = cd.clk->ops.clock_settime(cd.clk, ts); |
| 304 | else |
| 305 | err = -EOPNOTSUPP; |
| 306 | out: |
| 307 | put_clock_desc(&cd); |
| 308 | |
| 309 | return err; |
| 310 | } |
| 311 | |
| 312 | const struct k_clock clock_posix_dynamic = { |
| 313 | .clock_getres = pc_clock_getres, |
| 314 | .clock_set = pc_clock_settime, |
| 315 | .clock_get_timespec = pc_clock_gettime, |
| 316 | .clock_adj = pc_clock_adjtime, |
| 317 | }; |