xref: /linux/drivers/pps/pps.c (revision e58e871becec2d3b04ed91c0c16fe8deac9c9dfa) 
1 /*
2  * PPS core file
3  *
4  *
5  * Copyright (C) 2005-2009   Rodolfo Giometti <giometti@linux.it>
6  *
7  *   This program is free software; you can redistribute it and/or modify
8  *   it under the terms of the GNU General Public License as published by
9  *   the Free Software Foundation; either version 2 of the License, or
10  *   (at your option) any later version.
11  *
12  *   This program is distributed in the hope that it will be useful,
13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  *   GNU General Public License for more details.
16  *
17  *   You should have received a copy of the GNU General Public License
18  *   along with this program; if not, write to the Free Software
19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20  */
21 
22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23 
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/init.h>
27 #include <linux/sched.h>
28 #include <linux/uaccess.h>
29 #include <linux/idr.h>
30 #include <linux/mutex.h>
31 #include <linux/cdev.h>
32 #include <linux/poll.h>
33 #include <linux/pps_kernel.h>
34 #include <linux/slab.h>
35 
36 #include "kc.h"
37 
38 /*
39  * Local variables
40  */
41 
42 static dev_t pps_devt;
43 static struct class *pps_class;
44 
45 static DEFINE_MUTEX(pps_idr_lock);
46 static DEFINE_IDR(pps_idr);
47 
48 /*
49  * Char device methods
50  */
51 
52 static unsigned int pps_cdev_poll(struct file *file, poll_table *wait)
53 {
54 	struct pps_device *pps = file->private_data;
55 
56 	poll_wait(file, &pps->queue, wait);
57 
58 	return POLLIN | POLLRDNORM;
59 }
60 
61 static int pps_cdev_fasync(int fd, struct file *file, int on)
62 {
63 	struct pps_device *pps = file->private_data;
64 	return fasync_helper(fd, file, on, &pps->async_queue);
65 }
66 
67 static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
68 {
69 	unsigned int ev = pps->last_ev;
70 	int err = 0;
71 
72 	/* Manage the timeout */
73 	if (fdata->timeout.flags & PPS_TIME_INVALID)
74 		err = wait_event_interruptible(pps->queue,
75 				ev != pps->last_ev);
76 	else {
77 		unsigned long ticks;
78 
79 		dev_dbg(pps->dev, "timeout %lld.%09d\n",
80 				(long long) fdata->timeout.sec,
81 				fdata->timeout.nsec);
82 		ticks = fdata->timeout.sec * HZ;
83 		ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ);
84 
85 		if (ticks != 0) {
86 			err = wait_event_interruptible_timeout(
87 					pps->queue,
88 					ev != pps->last_ev,
89 					ticks);
90 			if (err == 0)
91 				return -ETIMEDOUT;
92 		}
93 	}
94 
95 	/* Check for pending signals */
96 	if (err == -ERESTARTSYS) {
97 		dev_dbg(pps->dev, "pending signal caught\n");
98 		return -EINTR;
99 	}
100 
101 	return 0;
102 }
103 
104 static long pps_cdev_ioctl(struct file *file,
105 		unsigned int cmd, unsigned long arg)
106 {
107 	struct pps_device *pps = file->private_data;
108 	struct pps_kparams params;
109 	void __user *uarg = (void __user *) arg;
110 	int __user *iuarg = (int __user *) arg;
111 	int err;
112 
113 	switch (cmd) {
114 	case PPS_GETPARAMS:
115 		dev_dbg(pps->dev, "PPS_GETPARAMS\n");
116 
117 		spin_lock_irq(&pps->lock);
118 
119 		/* Get the current parameters */
120 		params = pps->params;
121 
122 		spin_unlock_irq(&pps->lock);
123 
124 		err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
125 		if (err)
126 			return -EFAULT;
127 
128 		break;
129 
130 	case PPS_SETPARAMS:
131 		dev_dbg(pps->dev, "PPS_SETPARAMS\n");
132 
133 		/* Check the capabilities */
134 		if (!capable(CAP_SYS_TIME))
135 			return -EPERM;
136 
137 		err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
138 		if (err)
139 			return -EFAULT;
140 		if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
141 			dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
142 								params.mode);
143 			return -EINVAL;
144 		}
145 
146 		/* Check for supported capabilities */
147 		if ((params.mode & ~pps->info.mode) != 0) {
148 			dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
149 								params.mode);
150 			return -EINVAL;
151 		}
152 
153 		spin_lock_irq(&pps->lock);
154 
155 		/* Save the new parameters */
156 		pps->params = params;
157 
158 		/* Restore the read only parameters */
159 		if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
160 			/* section 3.3 of RFC 2783 interpreted */
161 			dev_dbg(pps->dev, "time format unspecified (%x)\n",
162 								params.mode);
163 			pps->params.mode |= PPS_TSFMT_TSPEC;
164 		}
165 		if (pps->info.mode & PPS_CANWAIT)
166 			pps->params.mode |= PPS_CANWAIT;
167 		pps->params.api_version = PPS_API_VERS;
168 
169 		spin_unlock_irq(&pps->lock);
170 
171 		break;
172 
173 	case PPS_GETCAP:
174 		dev_dbg(pps->dev, "PPS_GETCAP\n");
175 
176 		err = put_user(pps->info.mode, iuarg);
177 		if (err)
178 			return -EFAULT;
179 
180 		break;
181 
182 	case PPS_FETCH: {
183 		struct pps_fdata fdata;
184 
185 		dev_dbg(pps->dev, "PPS_FETCH\n");
186 
187 		err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
188 		if (err)
189 			return -EFAULT;
190 
191 		err = pps_cdev_pps_fetch(pps, &fdata);
192 		if (err)
193 			return err;
194 
195 		/* Return the fetched timestamp */
196 		spin_lock_irq(&pps->lock);
197 
198 		fdata.info.assert_sequence = pps->assert_sequence;
199 		fdata.info.clear_sequence = pps->clear_sequence;
200 		fdata.info.assert_tu = pps->assert_tu;
201 		fdata.info.clear_tu = pps->clear_tu;
202 		fdata.info.current_mode = pps->current_mode;
203 
204 		spin_unlock_irq(&pps->lock);
205 
206 		err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
207 		if (err)
208 			return -EFAULT;
209 
210 		break;
211 	}
212 	case PPS_KC_BIND: {
213 		struct pps_bind_args bind_args;
214 
215 		dev_dbg(pps->dev, "PPS_KC_BIND\n");
216 
217 		/* Check the capabilities */
218 		if (!capable(CAP_SYS_TIME))
219 			return -EPERM;
220 
221 		if (copy_from_user(&bind_args, uarg,
222 					sizeof(struct pps_bind_args)))
223 			return -EFAULT;
224 
225 		/* Check for supported capabilities */
226 		if ((bind_args.edge & ~pps->info.mode) != 0) {
227 			dev_err(pps->dev, "unsupported capabilities (%x)\n",
228 					bind_args.edge);
229 			return -EINVAL;
230 		}
231 
232 		/* Validate parameters roughly */
233 		if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
234 				(bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
235 				bind_args.consumer != PPS_KC_HARDPPS) {
236 			dev_err(pps->dev, "invalid kernel consumer bind"
237 					" parameters (%x)\n", bind_args.edge);
238 			return -EINVAL;
239 		}
240 
241 		err = pps_kc_bind(pps, &bind_args);
242 		if (err < 0)
243 			return err;
244 
245 		break;
246 	}
247 	default:
248 		return -ENOTTY;
249 	}
250 
251 	return 0;
252 }
253 
254 #ifdef CONFIG_COMPAT
255 static long pps_cdev_compat_ioctl(struct file *file,
256 		unsigned int cmd, unsigned long arg)
257 {
258 	struct pps_device *pps = file->private_data;
259 	void __user *uarg = (void __user *) arg;
260 
261 	cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
262 
263 	if (cmd == PPS_FETCH) {
264 		struct pps_fdata_compat compat;
265 		struct pps_fdata fdata;
266 		int err;
267 
268 		dev_dbg(pps->dev, "PPS_FETCH\n");
269 
270 		err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
271 		if (err)
272 			return -EFAULT;
273 
274 		memcpy(&fdata.timeout, &compat.timeout,
275 					sizeof(struct pps_ktime_compat));
276 
277 		err = pps_cdev_pps_fetch(pps, &fdata);
278 		if (err)
279 			return err;
280 
281 		/* Return the fetched timestamp */
282 		spin_lock_irq(&pps->lock);
283 
284 		compat.info.assert_sequence = pps->assert_sequence;
285 		compat.info.clear_sequence = pps->clear_sequence;
286 		compat.info.current_mode = pps->current_mode;
287 
288 		memcpy(&compat.info.assert_tu, &pps->assert_tu,
289 				sizeof(struct pps_ktime_compat));
290 		memcpy(&compat.info.clear_tu, &pps->clear_tu,
291 				sizeof(struct pps_ktime_compat));
292 
293 		spin_unlock_irq(&pps->lock);
294 
295 		return copy_to_user(uarg, &compat,
296 				sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
297 	}
298 
299 	return pps_cdev_ioctl(file, cmd, arg);
300 }
301 #else
302 #define pps_cdev_compat_ioctl	NULL
303 #endif
304 
305 static int pps_cdev_open(struct inode *inode, struct file *file)
306 {
307 	struct pps_device *pps = container_of(inode->i_cdev,
308 						struct pps_device, cdev);
309 	file->private_data = pps;
310 	kobject_get(&pps->dev->kobj);
311 	return 0;
312 }
313 
314 static int pps_cdev_release(struct inode *inode, struct file *file)
315 {
316 	struct pps_device *pps = container_of(inode->i_cdev,
317 						struct pps_device, cdev);
318 	kobject_put(&pps->dev->kobj);
319 	return 0;
320 }
321 
322 /*
323  * Char device stuff
324  */
325 
326 static const struct file_operations pps_cdev_fops = {
327 	.owner		= THIS_MODULE,
328 	.llseek		= no_llseek,
329 	.poll		= pps_cdev_poll,
330 	.fasync		= pps_cdev_fasync,
331 	.compat_ioctl	= pps_cdev_compat_ioctl,
332 	.unlocked_ioctl	= pps_cdev_ioctl,
333 	.open		= pps_cdev_open,
334 	.release	= pps_cdev_release,
335 };
336 
337 static void pps_device_destruct(struct device *dev)
338 {
339 	struct pps_device *pps = dev_get_drvdata(dev);
340 
341 	cdev_del(&pps->cdev);
342 
343 	/* Now we can release the ID for re-use */
344 	pr_debug("deallocating pps%d\n", pps->id);
345 	mutex_lock(&pps_idr_lock);
346 	idr_remove(&pps_idr, pps->id);
347 	mutex_unlock(&pps_idr_lock);
348 
349 	kfree(dev);
350 	kfree(pps);
351 }
352 
353 int pps_register_cdev(struct pps_device *pps)
354 {
355 	int err;
356 	dev_t devt;
357 
358 	mutex_lock(&pps_idr_lock);
359 	/*
360 	 * Get new ID for the new PPS source.  After idr_alloc() calling
361 	 * the new source will be freely available into the kernel.
362 	 */
363 	err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
364 	if (err < 0) {
365 		if (err == -ENOSPC) {
366 			pr_err("%s: too many PPS sources in the system\n",
367 			       pps->info.name);
368 			err = -EBUSY;
369 		}
370 		goto out_unlock;
371 	}
372 	pps->id = err;
373 	mutex_unlock(&pps_idr_lock);
374 
375 	devt = MKDEV(MAJOR(pps_devt), pps->id);
376 
377 	cdev_init(&pps->cdev, &pps_cdev_fops);
378 	pps->cdev.owner = pps->info.owner;
379 
380 	err = cdev_add(&pps->cdev, devt, 1);
381 	if (err) {
382 		pr_err("%s: failed to add char device %d:%d\n",
383 				pps->info.name, MAJOR(pps_devt), pps->id);
384 		goto free_idr;
385 	}
386 	pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
387 							"pps%d", pps->id);
388 	if (IS_ERR(pps->dev)) {
389 		err = PTR_ERR(pps->dev);
390 		goto del_cdev;
391 	}
392 
393 	/* Override the release function with our own */
394 	pps->dev->release = pps_device_destruct;
395 
396 	pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
397 			MAJOR(pps_devt), pps->id);
398 
399 	return 0;
400 
401 del_cdev:
402 	cdev_del(&pps->cdev);
403 
404 free_idr:
405 	mutex_lock(&pps_idr_lock);
406 	idr_remove(&pps_idr, pps->id);
407 out_unlock:
408 	mutex_unlock(&pps_idr_lock);
409 	return err;
410 }
411 
412 void pps_unregister_cdev(struct pps_device *pps)
413 {
414 	pr_debug("unregistering pps%d\n", pps->id);
415 	pps->lookup_cookie = NULL;
416 	device_destroy(pps_class, pps->dev->devt);
417 }
418 
419 /*
420  * Look up a pps device by magic cookie.
421  * The cookie is usually a pointer to some enclosing device, but this
422  * code doesn't care; you should never be dereferencing it.
423  *
424  * This is a bit of a kludge that is currently used only by the PPS
425  * serial line discipline.  It may need to be tweaked when a second user
426  * is found.
427  *
428  * There is no function interface for setting the lookup_cookie field.
429  * It's initialized to NULL when the pps device is created, and if a
430  * client wants to use it, just fill it in afterward.
431  *
432  * The cookie is automatically set to NULL in pps_unregister_source()
433  * so that it will not be used again, even if the pps device cannot
434  * be removed from the idr due to pending references holding the minor
435  * number in use.
436  */
437 struct pps_device *pps_lookup_dev(void const *cookie)
438 {
439 	struct pps_device *pps;
440 	unsigned id;
441 
442 	rcu_read_lock();
443 	idr_for_each_entry(&pps_idr, pps, id)
444 		if (cookie == pps->lookup_cookie)
445 			break;
446 	rcu_read_unlock();
447 	return pps;
448 }
449 EXPORT_SYMBOL(pps_lookup_dev);
450 
451 /*
452  * Module stuff
453  */
454 
455 static void __exit pps_exit(void)
456 {
457 	class_destroy(pps_class);
458 	unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
459 }
460 
461 static int __init pps_init(void)
462 {
463 	int err;
464 
465 	pps_class = class_create(THIS_MODULE, "pps");
466 	if (IS_ERR(pps_class)) {
467 		pr_err("failed to allocate class\n");
468 		return PTR_ERR(pps_class);
469 	}
470 	pps_class->dev_groups = pps_groups;
471 
472 	err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
473 	if (err < 0) {
474 		pr_err("failed to allocate char device region\n");
475 		goto remove_class;
476 	}
477 
478 	pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
479 	pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
480 		"<giometti@linux.it>\n", PPS_VERSION);
481 
482 	return 0;
483 
484 remove_class:
485 	class_destroy(pps_class);
486 
487 	return err;
488 }
489 
490 subsys_initcall(pps_init);
491 module_exit(pps_exit);
492 
493 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
494 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
495 MODULE_LICENSE("GPL");
496