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 }; 318