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 if (clk->ops.open) { 113 err = clk->ops.open(pccontext, fp->f_mode); 114 if (err) { 115 kfree(pccontext); 116 goto out; 117 } 118 } 119 120 fp->private_data = pccontext; 121 get_device(clk->dev); 122 err = 0; 123 out: 124 up_read(&clk->rwsem); 125 return err; 126 } 127 128 static int posix_clock_release(struct inode *inode, struct file *fp) 129 { 130 struct posix_clock_context *pccontext = fp->private_data; 131 struct posix_clock *clk; 132 int err = 0; 133 134 if (!pccontext) 135 return -ENODEV; 136 clk = pccontext->clk; 137 138 if (clk->ops.release) 139 err = clk->ops.release(pccontext); 140 141 put_device(clk->dev); 142 143 kfree(pccontext); 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 .read = posix_clock_read, 152 .poll = posix_clock_poll, 153 .unlocked_ioctl = posix_clock_ioctl, 154 .compat_ioctl = posix_clock_ioctl, 155 .open = posix_clock_open, 156 .release = posix_clock_release, 157 }; 158 159 int posix_clock_register(struct posix_clock *clk, struct device *dev) 160 { 161 int err; 162 163 init_rwsem(&clk->rwsem); 164 165 cdev_init(&clk->cdev, &posix_clock_file_operations); 166 err = cdev_device_add(&clk->cdev, dev); 167 if (err) { 168 pr_err("%s unable to add device %d:%d\n", 169 dev_name(dev), MAJOR(dev->devt), MINOR(dev->devt)); 170 return err; 171 } 172 clk->cdev.owner = clk->ops.owner; 173 clk->dev = dev; 174 175 return 0; 176 } 177 EXPORT_SYMBOL_GPL(posix_clock_register); 178 179 void posix_clock_unregister(struct posix_clock *clk) 180 { 181 cdev_device_del(&clk->cdev, clk->dev); 182 183 down_write(&clk->rwsem); 184 clk->zombie = true; 185 up_write(&clk->rwsem); 186 187 put_device(clk->dev); 188 } 189 EXPORT_SYMBOL_GPL(posix_clock_unregister); 190 191 struct posix_clock_desc { 192 struct file *fp; 193 struct posix_clock *clk; 194 }; 195 196 static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd) 197 { 198 struct file *fp = fget(clockid_to_fd(id)); 199 int err = -EINVAL; 200 201 if (!fp) 202 return err; 203 204 if (fp->f_op->open != posix_clock_open || !fp->private_data) 205 goto out; 206 207 cd->fp = fp; 208 cd->clk = get_posix_clock(fp); 209 210 err = cd->clk ? 0 : -ENODEV; 211 out: 212 if (err) 213 fput(fp); 214 return err; 215 } 216 217 static void put_clock_desc(struct posix_clock_desc *cd) 218 { 219 put_posix_clock(cd->clk); 220 fput(cd->fp); 221 } 222 223 static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx) 224 { 225 struct posix_clock_desc cd; 226 int err; 227 228 err = get_clock_desc(id, &cd); 229 if (err) 230 return err; 231 232 if ((cd.fp->f_mode & FMODE_WRITE) == 0) { 233 err = -EACCES; 234 goto out; 235 } 236 237 if (cd.clk->ops.clock_adjtime) 238 err = cd.clk->ops.clock_adjtime(cd.clk, tx); 239 else 240 err = -EOPNOTSUPP; 241 out: 242 put_clock_desc(&cd); 243 244 return err; 245 } 246 247 static int pc_clock_gettime(clockid_t id, struct timespec64 *ts) 248 { 249 struct posix_clock_desc cd; 250 int err; 251 252 err = get_clock_desc(id, &cd); 253 if (err) 254 return err; 255 256 if (cd.clk->ops.clock_gettime) 257 err = cd.clk->ops.clock_gettime(cd.clk, ts); 258 else 259 err = -EOPNOTSUPP; 260 261 put_clock_desc(&cd); 262 263 return err; 264 } 265 266 static int pc_clock_getres(clockid_t id, struct timespec64 *ts) 267 { 268 struct posix_clock_desc cd; 269 int err; 270 271 err = get_clock_desc(id, &cd); 272 if (err) 273 return err; 274 275 if (cd.clk->ops.clock_getres) 276 err = cd.clk->ops.clock_getres(cd.clk, ts); 277 else 278 err = -EOPNOTSUPP; 279 280 put_clock_desc(&cd); 281 282 return err; 283 } 284 285 static int pc_clock_settime(clockid_t id, const struct timespec64 *ts) 286 { 287 struct posix_clock_desc cd; 288 int err; 289 290 if (!timespec64_valid_strict(ts)) 291 return -EINVAL; 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