1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * PPS core file
4 *
5 * Copyright (C) 2005-2009 Rodolfo Giometti <giometti@linux.it>
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/sched.h>
14 #include <linux/uaccess.h>
15 #include <linux/idr.h>
16 #include <linux/mutex.h>
17 #include <linux/cdev.h>
18 #include <linux/poll.h>
19 #include <linux/pps_kernel.h>
20 #include <linux/slab.h>
21
22 #include "kc.h"
23
24 /*
25 * Local variables
26 */
27
28 static dev_t pps_devt;
29 static struct class *pps_class;
30
31 static DEFINE_MUTEX(pps_idr_lock);
32 static DEFINE_IDR(pps_idr);
33
34 /*
35 * Char device methods
36 */
37
pps_cdev_poll(struct file * file,poll_table * wait)38 static __poll_t pps_cdev_poll(struct file *file, poll_table *wait)
39 {
40 struct pps_device *pps = file->private_data;
41
42 poll_wait(file, &pps->queue, wait);
43
44 return EPOLLIN | EPOLLRDNORM;
45 }
46
pps_cdev_fasync(int fd,struct file * file,int on)47 static int pps_cdev_fasync(int fd, struct file *file, int on)
48 {
49 struct pps_device *pps = file->private_data;
50 return fasync_helper(fd, file, on, &pps->async_queue);
51 }
52
pps_cdev_pps_fetch(struct pps_device * pps,struct pps_fdata * fdata)53 static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
54 {
55 unsigned int ev = pps->last_ev;
56 int err = 0;
57
58 /* Manage the timeout */
59 if (fdata->timeout.flags & PPS_TIME_INVALID)
60 err = wait_event_interruptible(pps->queue,
61 ev != pps->last_ev);
62 else {
63 unsigned long ticks;
64
65 dev_dbg(pps->dev, "timeout %lld.%09d\n",
66 (long long) fdata->timeout.sec,
67 fdata->timeout.nsec);
68 ticks = fdata->timeout.sec * HZ;
69 ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ);
70
71 if (ticks != 0) {
72 err = wait_event_interruptible_timeout(
73 pps->queue,
74 ev != pps->last_ev,
75 ticks);
76 if (err == 0)
77 return -ETIMEDOUT;
78 }
79 }
80
81 /* Check for pending signals */
82 if (err == -ERESTARTSYS) {
83 dev_dbg(pps->dev, "pending signal caught\n");
84 return -EINTR;
85 }
86
87 return 0;
88 }
89
pps_cdev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)90 static long pps_cdev_ioctl(struct file *file,
91 unsigned int cmd, unsigned long arg)
92 {
93 struct pps_device *pps = file->private_data;
94 struct pps_kparams params;
95 void __user *uarg = (void __user *) arg;
96 int __user *iuarg = (int __user *) arg;
97 int err;
98
99 switch (cmd) {
100 case PPS_GETPARAMS:
101 dev_dbg(pps->dev, "PPS_GETPARAMS\n");
102
103 spin_lock_irq(&pps->lock);
104
105 /* Get the current parameters */
106 params = pps->params;
107
108 spin_unlock_irq(&pps->lock);
109
110 err = copy_to_user(uarg, ¶ms, sizeof(struct pps_kparams));
111 if (err)
112 return -EFAULT;
113
114 break;
115
116 case PPS_SETPARAMS:
117 dev_dbg(pps->dev, "PPS_SETPARAMS\n");
118
119 /* Check the capabilities */
120 if (!capable(CAP_SYS_TIME))
121 return -EPERM;
122
123 err = copy_from_user(¶ms, uarg, sizeof(struct pps_kparams));
124 if (err)
125 return -EFAULT;
126 if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
127 dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
128 params.mode);
129 return -EINVAL;
130 }
131
132 /* Check for supported capabilities */
133 if ((params.mode & ~pps->info.mode) != 0) {
134 dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
135 params.mode);
136 return -EINVAL;
137 }
138
139 spin_lock_irq(&pps->lock);
140
141 /* Save the new parameters */
142 pps->params = params;
143
144 /* Restore the read only parameters */
145 if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
146 /* section 3.3 of RFC 2783 interpreted */
147 dev_dbg(pps->dev, "time format unspecified (%x)\n",
148 params.mode);
149 pps->params.mode |= PPS_TSFMT_TSPEC;
150 }
151 if (pps->info.mode & PPS_CANWAIT)
152 pps->params.mode |= PPS_CANWAIT;
153 pps->params.api_version = PPS_API_VERS;
154
155 /*
156 * Clear unused fields of pps_kparams to avoid leaking
157 * uninitialized data of the PPS_SETPARAMS caller via
158 * PPS_GETPARAMS
159 */
160 pps->params.assert_off_tu.flags = 0;
161 pps->params.clear_off_tu.flags = 0;
162
163 spin_unlock_irq(&pps->lock);
164
165 break;
166
167 case PPS_GETCAP:
168 dev_dbg(pps->dev, "PPS_GETCAP\n");
169
170 err = put_user(pps->info.mode, iuarg);
171 if (err)
172 return -EFAULT;
173
174 break;
175
176 case PPS_FETCH: {
177 struct pps_fdata fdata;
178
179 dev_dbg(pps->dev, "PPS_FETCH\n");
180
181 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
182 if (err)
183 return -EFAULT;
184
185 err = pps_cdev_pps_fetch(pps, &fdata);
186 if (err)
187 return err;
188
189 /* Return the fetched timestamp */
190 spin_lock_irq(&pps->lock);
191
192 fdata.info.assert_sequence = pps->assert_sequence;
193 fdata.info.clear_sequence = pps->clear_sequence;
194 fdata.info.assert_tu = pps->assert_tu;
195 fdata.info.clear_tu = pps->clear_tu;
196 fdata.info.current_mode = pps->current_mode;
197
198 spin_unlock_irq(&pps->lock);
199
200 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
201 if (err)
202 return -EFAULT;
203
204 break;
205 }
206 case PPS_KC_BIND: {
207 struct pps_bind_args bind_args;
208
209 dev_dbg(pps->dev, "PPS_KC_BIND\n");
210
211 /* Check the capabilities */
212 if (!capable(CAP_SYS_TIME))
213 return -EPERM;
214
215 if (copy_from_user(&bind_args, uarg,
216 sizeof(struct pps_bind_args)))
217 return -EFAULT;
218
219 /* Check for supported capabilities */
220 if ((bind_args.edge & ~pps->info.mode) != 0) {
221 dev_err(pps->dev, "unsupported capabilities (%x)\n",
222 bind_args.edge);
223 return -EINVAL;
224 }
225
226 /* Validate parameters roughly */
227 if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
228 (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
229 bind_args.consumer != PPS_KC_HARDPPS) {
230 dev_err(pps->dev, "invalid kernel consumer bind"
231 " parameters (%x)\n", bind_args.edge);
232 return -EINVAL;
233 }
234
235 err = pps_kc_bind(pps, &bind_args);
236 if (err < 0)
237 return err;
238
239 break;
240 }
241 default:
242 return -ENOTTY;
243 }
244
245 return 0;
246 }
247
248 #ifdef CONFIG_COMPAT
pps_cdev_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)249 static long pps_cdev_compat_ioctl(struct file *file,
250 unsigned int cmd, unsigned long arg)
251 {
252 struct pps_device *pps = file->private_data;
253 void __user *uarg = (void __user *) arg;
254
255 cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
256
257 if (cmd == PPS_FETCH) {
258 struct pps_fdata_compat compat;
259 struct pps_fdata fdata;
260 int err;
261
262 dev_dbg(pps->dev, "PPS_FETCH\n");
263
264 err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
265 if (err)
266 return -EFAULT;
267
268 memcpy(&fdata.timeout, &compat.timeout,
269 sizeof(struct pps_ktime_compat));
270
271 err = pps_cdev_pps_fetch(pps, &fdata);
272 if (err)
273 return err;
274
275 /* Return the fetched timestamp */
276 spin_lock_irq(&pps->lock);
277
278 compat.info.assert_sequence = pps->assert_sequence;
279 compat.info.clear_sequence = pps->clear_sequence;
280 compat.info.current_mode = pps->current_mode;
281
282 memcpy(&compat.info.assert_tu, &pps->assert_tu,
283 sizeof(struct pps_ktime_compat));
284 memcpy(&compat.info.clear_tu, &pps->clear_tu,
285 sizeof(struct pps_ktime_compat));
286
287 spin_unlock_irq(&pps->lock);
288
289 return copy_to_user(uarg, &compat,
290 sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
291 }
292
293 return pps_cdev_ioctl(file, cmd, arg);
294 }
295 #else
296 #define pps_cdev_compat_ioctl NULL
297 #endif
298
pps_cdev_open(struct inode * inode,struct file * file)299 static int pps_cdev_open(struct inode *inode, struct file *file)
300 {
301 struct pps_device *pps = container_of(inode->i_cdev,
302 struct pps_device, cdev);
303 file->private_data = pps;
304 kobject_get(&pps->dev->kobj);
305 return 0;
306 }
307
pps_cdev_release(struct inode * inode,struct file * file)308 static int pps_cdev_release(struct inode *inode, struct file *file)
309 {
310 struct pps_device *pps = container_of(inode->i_cdev,
311 struct pps_device, cdev);
312 kobject_put(&pps->dev->kobj);
313 return 0;
314 }
315
316 /*
317 * Char device stuff
318 */
319
320 static const struct file_operations pps_cdev_fops = {
321 .owner = THIS_MODULE,
322 .poll = pps_cdev_poll,
323 .fasync = pps_cdev_fasync,
324 .compat_ioctl = pps_cdev_compat_ioctl,
325 .unlocked_ioctl = pps_cdev_ioctl,
326 .open = pps_cdev_open,
327 .release = pps_cdev_release,
328 };
329
pps_device_destruct(struct device * dev)330 static void pps_device_destruct(struct device *dev)
331 {
332 struct pps_device *pps = dev_get_drvdata(dev);
333
334 cdev_del(&pps->cdev);
335
336 /* Now we can release the ID for re-use */
337 pr_debug("deallocating pps%d\n", pps->id);
338 mutex_lock(&pps_idr_lock);
339 idr_remove(&pps_idr, pps->id);
340 mutex_unlock(&pps_idr_lock);
341
342 kfree(dev);
343 kfree(pps);
344 }
345
pps_register_cdev(struct pps_device * pps)346 int pps_register_cdev(struct pps_device *pps)
347 {
348 int err;
349 dev_t devt;
350
351 mutex_lock(&pps_idr_lock);
352 /*
353 * Get new ID for the new PPS source. After idr_alloc() calling
354 * the new source will be freely available into the kernel.
355 */
356 err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
357 if (err < 0) {
358 if (err == -ENOSPC) {
359 pr_err("%s: too many PPS sources in the system\n",
360 pps->info.name);
361 err = -EBUSY;
362 }
363 goto out_unlock;
364 }
365 pps->id = err;
366 mutex_unlock(&pps_idr_lock);
367
368 devt = MKDEV(MAJOR(pps_devt), pps->id);
369
370 cdev_init(&pps->cdev, &pps_cdev_fops);
371 pps->cdev.owner = pps->info.owner;
372
373 err = cdev_add(&pps->cdev, devt, 1);
374 if (err) {
375 pr_err("%s: failed to add char device %d:%d\n",
376 pps->info.name, MAJOR(pps_devt), pps->id);
377 goto free_idr;
378 }
379 pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
380 "pps%d", pps->id);
381 if (IS_ERR(pps->dev)) {
382 err = PTR_ERR(pps->dev);
383 goto del_cdev;
384 }
385
386 /* Override the release function with our own */
387 pps->dev->release = pps_device_destruct;
388
389 pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
390 MAJOR(pps_devt), pps->id);
391
392 return 0;
393
394 del_cdev:
395 cdev_del(&pps->cdev);
396
397 free_idr:
398 mutex_lock(&pps_idr_lock);
399 idr_remove(&pps_idr, pps->id);
400 out_unlock:
401 mutex_unlock(&pps_idr_lock);
402 return err;
403 }
404
pps_unregister_cdev(struct pps_device * pps)405 void pps_unregister_cdev(struct pps_device *pps)
406 {
407 pr_debug("unregistering pps%d\n", pps->id);
408 pps->lookup_cookie = NULL;
409 device_destroy(pps_class, pps->dev->devt);
410 }
411
412 /*
413 * Look up a pps device by magic cookie.
414 * The cookie is usually a pointer to some enclosing device, but this
415 * code doesn't care; you should never be dereferencing it.
416 *
417 * This is a bit of a kludge that is currently used only by the PPS
418 * serial line discipline. It may need to be tweaked when a second user
419 * is found.
420 *
421 * There is no function interface for setting the lookup_cookie field.
422 * It's initialized to NULL when the pps device is created, and if a
423 * client wants to use it, just fill it in afterward.
424 *
425 * The cookie is automatically set to NULL in pps_unregister_source()
426 * so that it will not be used again, even if the pps device cannot
427 * be removed from the idr due to pending references holding the minor
428 * number in use.
429 */
pps_lookup_dev(void const * cookie)430 struct pps_device *pps_lookup_dev(void const *cookie)
431 {
432 struct pps_device *pps;
433 unsigned id;
434
435 rcu_read_lock();
436 idr_for_each_entry(&pps_idr, pps, id)
437 if (cookie == pps->lookup_cookie)
438 break;
439 rcu_read_unlock();
440 return pps;
441 }
442 EXPORT_SYMBOL(pps_lookup_dev);
443
444 /*
445 * Module stuff
446 */
447
pps_exit(void)448 static void __exit pps_exit(void)
449 {
450 class_destroy(pps_class);
451 unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
452 }
453
pps_init(void)454 static int __init pps_init(void)
455 {
456 int err;
457
458 pps_class = class_create("pps");
459 if (IS_ERR(pps_class)) {
460 pr_err("failed to allocate class\n");
461 return PTR_ERR(pps_class);
462 }
463 pps_class->dev_groups = pps_groups;
464
465 err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
466 if (err < 0) {
467 pr_err("failed to allocate char device region\n");
468 goto remove_class;
469 }
470
471 pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
472 pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
473 "<giometti@linux.it>\n", PPS_VERSION);
474
475 return 0;
476
477 remove_class:
478 class_destroy(pps_class);
479
480 return err;
481 }
482
483 subsys_initcall(pps_init);
484 module_exit(pps_exit);
485
486 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
487 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
488 MODULE_LICENSE("GPL");
489