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 fp->private_data = pccontext; 133 if (clk->ops.open) 134 err = clk->ops.open(pccontext, fp->f_mode); 135 else 136 err = 0; 137 138 if (!err) { 139 get_device(clk->dev); 140 } 141 out: 142 up_read(&clk->rwsem); 143 return err; 144 } 145 146 static int posix_clock_release(struct inode *inode, struct file *fp) 147 { 148 struct posix_clock_context *pccontext = fp->private_data; 149 struct posix_clock *clk; 150 int err = 0; 151 152 if (!pccontext) 153 return -ENODEV; 154 clk = pccontext->clk; 155 156 if (clk->ops.release) 157 err = clk->ops.release(pccontext); 158 159 put_device(clk->dev); 160 161 kfree(pccontext); 162 fp->private_data = NULL; 163 164 return err; 165 } 166 167 static const struct file_operations posix_clock_file_operations = { 168 .owner = THIS_MODULE, 169 .llseek = no_llseek, 170 .read = posix_clock_read, 171 .poll = posix_clock_poll, 172 .unlocked_ioctl = posix_clock_ioctl, 173 .open = posix_clock_open, 174 .release = posix_clock_release, 175 #ifdef CONFIG_COMPAT 176 .compat_ioctl = posix_clock_compat_ioctl, 177 #endif 178 }; 179 180 int posix_clock_register(struct posix_clock *clk, struct device *dev) 181 { 182 int err; 183 184 init_rwsem(&clk->rwsem); 185 186 cdev_init(&clk->cdev, &posix_clock_file_operations); 187 err = cdev_device_add(&clk->cdev, dev); 188 if (err) { 189 pr_err("%s unable to add device %d:%d\n", 190 dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt)); 191 return err; 192 } 193 clk->cdev.owner = clk->ops.owner; 194 clk->dev = dev; 195 196 return 0; 197 } 198 EXPORT_SYMBOL_GPL(posix_clock_register); 199 200 void posix_clock_unregister(struct posix_clock *clk) 201 { 202 cdev_device_del(&clk->cdev, clk->dev); 203 204 down_write(&clk->rwsem); 205 clk->zombie = true; 206 up_write(&clk->rwsem); 207 208 put_device(clk->dev); 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 __kernel_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_timespec = pc_clock_gettime, 334 .clock_adj = pc_clock_adjtime, 335 }; 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