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 static int posix_clock_open(struct inode *inode, struct file *fp) 94 { 95 int err; 96 struct posix_clock *clk = 97 container_of(inode->i_cdev, struct posix_clock, cdev); 98 struct posix_clock_context *pccontext; 99 100 down_read(&clk->rwsem); 101 102 if (clk->zombie) { 103 err = -ENODEV; 104 goto out; 105 } 106 pccontext = kzalloc(sizeof(*pccontext), GFP_KERNEL); 107 if (!pccontext) { 108 err = -ENOMEM; 109 goto out; 110 } 111 pccontext->clk = clk; 112 pccontext->fp = fp; 113 if (clk->ops.open) { 114 err = clk->ops.open(pccontext, fp->f_mode); 115 if (err) { 116 kfree(pccontext); 117 goto out; 118 } 119 } 120 121 fp->private_data = pccontext; 122 get_device(clk->dev); 123 err = 0; 124 out: 125 up_read(&clk->rwsem); 126 return err; 127 } 128 129 static int posix_clock_release(struct inode *inode, struct file *fp) 130 { 131 struct posix_clock_context *pccontext = fp->private_data; 132 struct posix_clock *clk; 133 int err = 0; 134 135 if (!pccontext) 136 return -ENODEV; 137 clk = pccontext->clk; 138 139 if (clk->ops.release) 140 err = clk->ops.release(pccontext); 141 142 put_device(clk->dev); 143 144 kfree(pccontext); 145 fp->private_data = NULL; 146 147 return err; 148 } 149 150 static const struct file_operations posix_clock_file_operations = { 151 .owner = THIS_MODULE, 152 .read = posix_clock_read, 153 .poll = posix_clock_poll, 154 .unlocked_ioctl = posix_clock_ioctl, 155 .compat_ioctl = posix_clock_ioctl, 156 .open = posix_clock_open, 157 .release = posix_clock_release, 158 }; 159 160 int posix_clock_register(struct posix_clock *clk, struct device *dev) 161 { 162 int err; 163 164 init_rwsem(&clk->rwsem); 165 166 cdev_init(&clk->cdev, &posix_clock_file_operations); 167 err = cdev_device_add(&clk->cdev, dev); 168 if (err) { 169 pr_err("%s unable to add device %d:%d\n", 170 dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt)); 171 return err; 172 } 173 clk->cdev.owner = clk->ops.owner; 174 clk->dev = dev; 175 176 return 0; 177 } 178 EXPORT_SYMBOL_GPL(posix_clock_register); 179 180 void posix_clock_unregister(struct posix_clock *clk) 181 { 182 cdev_device_del(&clk->cdev, clk->dev); 183 184 down_write(&clk->rwsem); 185 clk->zombie = true; 186 up_write(&clk->rwsem); 187 188 put_device(clk->dev); 189 } 190 EXPORT_SYMBOL_GPL(posix_clock_unregister); 191 192 struct posix_clock_desc { 193 struct file *fp; 194 struct posix_clock *clk; 195 }; 196 197 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd) 198 { 199 struct file *fp = fget(clockid_to_fd(id)); 200 int err = -EINVAL; 201 202 if (!fp) 203 return err; 204 205 if (fp->f_op->open != posix_clock_open || !fp->private_data) 206 goto out; 207 208 cd->fp = fp; 209 cd->clk = get_posix_clock(fp); 210 211 err = cd->clk ? 0 : -ENODEV; 212 out: 213 if (err) 214 fput(fp); 215 return err; 216 } 217 218 static void put_clock_desc(struct posix_clock_desc *cd) 219 { 220 put_posix_clock(cd->clk); 221 fput(cd->fp); 222 } 223 224 static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx) 225 { 226 struct posix_clock_desc cd; 227 int err; 228 229 err = get_clock_desc(id, &cd); 230 if (err) 231 return err; 232 233 if (tx->modes && (cd.fp->f_mode & FMODE_WRITE) == 0) { 234 err = -EACCES; 235 goto out; 236 } 237 238 if (cd.clk->ops.clock_adjtime) 239 err = cd.clk->ops.clock_adjtime(cd.clk, tx); 240 else 241 err = -EOPNOTSUPP; 242 out: 243 put_clock_desc(&cd); 244 245 return err; 246 } 247 248 static int pc_clock_gettime(clockid_t id, struct timespec64 *ts) 249 { 250 struct posix_clock_desc cd; 251 int err; 252 253 err = get_clock_desc(id, &cd); 254 if (err) 255 return err; 256 257 if (cd.clk->ops.clock_gettime) 258 err = cd.clk->ops.clock_gettime(cd.clk, ts); 259 else 260 err = -EOPNOTSUPP; 261 262 put_clock_desc(&cd); 263 264 return err; 265 } 266 267 static int pc_clock_getres(clockid_t id, struct timespec64 *ts) 268 { 269 struct posix_clock_desc cd; 270 int err; 271 272 err = get_clock_desc(id, &cd); 273 if (err) 274 return err; 275 276 if (cd.clk->ops.clock_getres) 277 err = cd.clk->ops.clock_getres(cd.clk, ts); 278 else 279 err = -EOPNOTSUPP; 280 281 put_clock_desc(&cd); 282 283 return err; 284 } 285 286 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts) 287 { 288 struct posix_clock_desc cd; 289 int err; 290 291 if (!timespec64_valid_strict(ts)) 292 return -EINVAL; 293 294 err = get_clock_desc(id, &cd); 295 if (err) 296 return err; 297 298 if ((cd.fp->f_mode & FMODE_WRITE) == 0) { 299 err = -EACCES; 300 goto out; 301 } 302 303 if (cd.clk->ops.clock_settime) 304 err = cd.clk->ops.clock_settime(cd.clk, ts); 305 else 306 err = -EOPNOTSUPP; 307 out: 308 put_clock_desc(&cd); 309 310 return err; 311 } 312 313 const struct k_clock clock_posix_dynamic = { 314 .clock_getres = pc_clock_getres, 315 .clock_set = pc_clock_settime, 316 .clock_get_timespec = pc_clock_gettime, 317 .clock_adj = pc_clock_adjtime, 318 }; 319