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_context *pccontext = fp->private_data; 23 struct posix_clock *clk = pccontext->clk; 24 25 down_read(&clk->rwsem); 26 27 if (!clk->zombie) 28 return clk; 29 30 up_read(&clk->rwsem); 31 32 return NULL; 33 } 34 35 static void put_posix_clock(struct posix_clock *clk) 36 { 37 up_read(&clk->rwsem); 38 } 39 40 static ssize_t posix_clock_read(struct file *fp, char __user *buf, 41 size_t count, loff_t *ppos) 42 { 43 struct posix_clock_context *pccontext = fp->private_data; 44 struct posix_clock *clk = get_posix_clock(fp); 45 int err = -EINVAL; 46 47 if (!clk) 48 return -ENODEV; 49 50 if (clk->ops.read) 51 err = clk->ops.read(pccontext, fp->f_flags, buf, count); 52 53 put_posix_clock(clk); 54 55 return err; 56 } 57 58 static __poll_t posix_clock_poll(struct file *fp, poll_table *wait) 59 { 60 struct posix_clock_context *pccontext = fp->private_data; 61 struct posix_clock *clk = get_posix_clock(fp); 62 __poll_t result = 0; 63 64 if (!clk) 65 return EPOLLERR; 66 67 if (clk->ops.poll) 68 result = clk->ops.poll(pccontext, fp, wait); 69 70 put_posix_clock(clk); 71 72 return result; 73 } 74 75 static long posix_clock_ioctl(struct file *fp, 76 unsigned int cmd, unsigned long arg) 77 { 78 struct posix_clock_context *pccontext = fp->private_data; 79 struct posix_clock *clk = get_posix_clock(fp); 80 int err = -ENOTTY; 81 82 if (!clk) 83 return -ENODEV; 84 85 if (clk->ops.ioctl) 86 err = clk->ops.ioctl(pccontext, cmd, arg); 87 88 put_posix_clock(clk); 89 90 return err; 91 } 92 93 #ifdef CONFIG_COMPAT 94 static long posix_clock_compat_ioctl(struct file *fp, 95 unsigned int cmd, unsigned long arg) 96 { 97 struct posix_clock_context *pccontext = fp->private_data; 98 struct posix_clock *clk = get_posix_clock(fp); 99 int err = -ENOTTY; 100 101 if (!clk) 102 return -ENODEV; 103 104 if (clk->ops.ioctl) 105 err = clk->ops.ioctl(pccontext, cmd, arg); 106 107 put_posix_clock(clk); 108 109 return err; 110 } 111 #endif 112 113 static int posix_clock_open(struct inode *inode, struct file *fp) 114 { 115 int err; 116 struct posix_clock *clk = 117 container_of(inode->i_cdev, struct posix_clock, cdev); 118 struct posix_clock_context *pccontext; 119 120 down_read(&clk->rwsem); 121 122 if (clk->zombie) { 123 err = -ENODEV; 124 goto out; 125 } 126 pccontext = kzalloc(sizeof(*pccontext), GFP_KERNEL); 127 if (!pccontext) { 128 err = -ENOMEM; 129 goto out; 130 } 131 pccontext->clk = clk; 132 if (clk->ops.open) { 133 err = clk->ops.open(pccontext, fp->f_mode); 134 if (err) { 135 kfree(pccontext); 136 goto out; 137 } 138 } 139 140 fp->private_data = pccontext; 141 get_device(clk->dev); 142 err = 0; 143 out: 144 up_read(&clk->rwsem); 145 return err; 146 } 147 148 static int posix_clock_release(struct inode *inode, struct file *fp) 149 { 150 struct posix_clock_context *pccontext = fp->private_data; 151 struct posix_clock *clk; 152 int err = 0; 153 154 if (!pccontext) 155 return -ENODEV; 156 clk = pccontext->clk; 157 158 if (clk->ops.release) 159 err = clk->ops.release(pccontext); 160 161 put_device(clk->dev); 162 163 kfree(pccontext); 164 fp->private_data = NULL; 165 166 return err; 167 } 168 169 static const struct file_operations posix_clock_file_operations = { 170 .owner = THIS_MODULE, 171 .read = posix_clock_read, 172 .poll = posix_clock_poll, 173 .unlocked_ioctl = posix_clock_ioctl, 174 .open = posix_clock_open, 175 .release = posix_clock_release, 176 #ifdef CONFIG_COMPAT 177 .compat_ioctl = posix_clock_compat_ioctl, 178 #endif 179 }; 180 181 int posix_clock_register(struct posix_clock *clk, struct device *dev) 182 { 183 int err; 184 185 init_rwsem(&clk->rwsem); 186 187 cdev_init(&clk->cdev, &posix_clock_file_operations); 188 err = cdev_device_add(&clk->cdev, dev); 189 if (err) { 190 pr_err("%s unable to add device %d:%d\n", 191 dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt)); 192 return err; 193 } 194 clk->cdev.owner = clk->ops.owner; 195 clk->dev = dev; 196 197 return 0; 198 } 199 EXPORT_SYMBOL_GPL(posix_clock_register); 200 201 void posix_clock_unregister(struct posix_clock *clk) 202 { 203 cdev_device_del(&clk->cdev, clk->dev); 204 205 down_write(&clk->rwsem); 206 clk->zombie = true; 207 up_write(&clk->rwsem); 208 209 put_device(clk->dev); 210 } 211 EXPORT_SYMBOL_GPL(posix_clock_unregister); 212 213 struct posix_clock_desc { 214 struct file *fp; 215 struct posix_clock *clk; 216 }; 217 218 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd) 219 { 220 struct file *fp = fget(clockid_to_fd(id)); 221 int err = -EINVAL; 222 223 if (!fp) 224 return err; 225 226 if (fp->f_op->open != posix_clock_open || !fp->private_data) 227 goto out; 228 229 cd->fp = fp; 230 cd->clk = get_posix_clock(fp); 231 232 err = cd->clk ? 0 : -ENODEV; 233 out: 234 if (err) 235 fput(fp); 236 return err; 237 } 238 239 static void put_clock_desc(struct posix_clock_desc *cd) 240 { 241 put_posix_clock(cd->clk); 242 fput(cd->fp); 243 } 244 245 static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx) 246 { 247 struct posix_clock_desc cd; 248 int err; 249 250 err = get_clock_desc(id, &cd); 251 if (err) 252 return err; 253 254 if ((cd.fp->f_mode & FMODE_WRITE) == 0) { 255 err = -EACCES; 256 goto out; 257 } 258 259 if (cd.clk->ops.clock_adjtime) 260 err = cd.clk->ops.clock_adjtime(cd.clk, tx); 261 else 262 err = -EOPNOTSUPP; 263 out: 264 put_clock_desc(&cd); 265 266 return err; 267 } 268 269 static int pc_clock_gettime(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_gettime) 279 err = cd.clk->ops.clock_gettime(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_getres(clockid_t id, 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.clk->ops.clock_getres) 298 err = cd.clk->ops.clock_getres(cd.clk, ts); 299 else 300 err = -EOPNOTSUPP; 301 302 put_clock_desc(&cd); 303 304 return err; 305 } 306 307 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts) 308 { 309 struct posix_clock_desc cd; 310 int err; 311 312 err = get_clock_desc(id, &cd); 313 if (err) 314 return err; 315 316 if ((cd.fp->f_mode & FMODE_WRITE) == 0) { 317 err = -EACCES; 318 goto out; 319 } 320 321 if (!timespec64_valid_strict(ts)) 322 return -EINVAL; 323 324 if (cd.clk->ops.clock_settime) 325 err = cd.clk->ops.clock_settime(cd.clk, ts); 326 else 327 err = -EOPNOTSUPP; 328 out: 329 put_clock_desc(&cd); 330 331 return err; 332 } 333 334 const struct k_clock clock_posix_dynamic = { 335 .clock_getres = pc_clock_getres, 336 .clock_set = pc_clock_settime, 337 .clock_get_timespec = pc_clock_gettime, 338 .clock_adj = pc_clock_adjtime, 339 }; 340