xref: /openbmc/linux/drivers/pps/pps.c (revision 96ac6d43) 
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 
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 
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 
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 
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, &params, 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(&params, 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 		spin_unlock_irq(&pps->lock);
156 
157 		break;
158 
159 	case PPS_GETCAP:
160 		dev_dbg(pps->dev, "PPS_GETCAP\n");
161 
162 		err = put_user(pps->info.mode, iuarg);
163 		if (err)
164 			return -EFAULT;
165 
166 		break;
167 
168 	case PPS_FETCH: {
169 		struct pps_fdata fdata;
170 
171 		dev_dbg(pps->dev, "PPS_FETCH\n");
172 
173 		err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
174 		if (err)
175 			return -EFAULT;
176 
177 		err = pps_cdev_pps_fetch(pps, &fdata);
178 		if (err)
179 			return err;
180 
181 		/* Return the fetched timestamp */
182 		spin_lock_irq(&pps->lock);
183 
184 		fdata.info.assert_sequence = pps->assert_sequence;
185 		fdata.info.clear_sequence = pps->clear_sequence;
186 		fdata.info.assert_tu = pps->assert_tu;
187 		fdata.info.clear_tu = pps->clear_tu;
188 		fdata.info.current_mode = pps->current_mode;
189 
190 		spin_unlock_irq(&pps->lock);
191 
192 		err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
193 		if (err)
194 			return -EFAULT;
195 
196 		break;
197 	}
198 	case PPS_KC_BIND: {
199 		struct pps_bind_args bind_args;
200 
201 		dev_dbg(pps->dev, "PPS_KC_BIND\n");
202 
203 		/* Check the capabilities */
204 		if (!capable(CAP_SYS_TIME))
205 			return -EPERM;
206 
207 		if (copy_from_user(&bind_args, uarg,
208 					sizeof(struct pps_bind_args)))
209 			return -EFAULT;
210 
211 		/* Check for supported capabilities */
212 		if ((bind_args.edge & ~pps->info.mode) != 0) {
213 			dev_err(pps->dev, "unsupported capabilities (%x)\n",
214 					bind_args.edge);
215 			return -EINVAL;
216 		}
217 
218 		/* Validate parameters roughly */
219 		if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
220 				(bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
221 				bind_args.consumer != PPS_KC_HARDPPS) {
222 			dev_err(pps->dev, "invalid kernel consumer bind"
223 					" parameters (%x)\n", bind_args.edge);
224 			return -EINVAL;
225 		}
226 
227 		err = pps_kc_bind(pps, &bind_args);
228 		if (err < 0)
229 			return err;
230 
231 		break;
232 	}
233 	default:
234 		return -ENOTTY;
235 	}
236 
237 	return 0;
238 }
239 
240 #ifdef CONFIG_COMPAT
241 static long pps_cdev_compat_ioctl(struct file *file,
242 		unsigned int cmd, unsigned long arg)
243 {
244 	struct pps_device *pps = file->private_data;
245 	void __user *uarg = (void __user *) arg;
246 
247 	cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
248 
249 	if (cmd == PPS_FETCH) {
250 		struct pps_fdata_compat compat;
251 		struct pps_fdata fdata;
252 		int err;
253 
254 		dev_dbg(pps->dev, "PPS_FETCH\n");
255 
256 		err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
257 		if (err)
258 			return -EFAULT;
259 
260 		memcpy(&fdata.timeout, &compat.timeout,
261 					sizeof(struct pps_ktime_compat));
262 
263 		err = pps_cdev_pps_fetch(pps, &fdata);
264 		if (err)
265 			return err;
266 
267 		/* Return the fetched timestamp */
268 		spin_lock_irq(&pps->lock);
269 
270 		compat.info.assert_sequence = pps->assert_sequence;
271 		compat.info.clear_sequence = pps->clear_sequence;
272 		compat.info.current_mode = pps->current_mode;
273 
274 		memcpy(&compat.info.assert_tu, &pps->assert_tu,
275 				sizeof(struct pps_ktime_compat));
276 		memcpy(&compat.info.clear_tu, &pps->clear_tu,
277 				sizeof(struct pps_ktime_compat));
278 
279 		spin_unlock_irq(&pps->lock);
280 
281 		return copy_to_user(uarg, &compat,
282 				sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
283 	}
284 
285 	return pps_cdev_ioctl(file, cmd, arg);
286 }
287 #else
288 #define pps_cdev_compat_ioctl	NULL
289 #endif
290 
291 static int pps_cdev_open(struct inode *inode, struct file *file)
292 {
293 	struct pps_device *pps = container_of(inode->i_cdev,
294 						struct pps_device, cdev);
295 	file->private_data = pps;
296 	kobject_get(&pps->dev->kobj);
297 	return 0;
298 }
299 
300 static int pps_cdev_release(struct inode *inode, struct file *file)
301 {
302 	struct pps_device *pps = container_of(inode->i_cdev,
303 						struct pps_device, cdev);
304 	kobject_put(&pps->dev->kobj);
305 	return 0;
306 }
307 
308 /*
309  * Char device stuff
310  */
311 
312 static const struct file_operations pps_cdev_fops = {
313 	.owner		= THIS_MODULE,
314 	.llseek		= no_llseek,
315 	.poll		= pps_cdev_poll,
316 	.fasync		= pps_cdev_fasync,
317 	.compat_ioctl	= pps_cdev_compat_ioctl,
318 	.unlocked_ioctl	= pps_cdev_ioctl,
319 	.open		= pps_cdev_open,
320 	.release	= pps_cdev_release,
321 };
322 
323 static void pps_device_destruct(struct device *dev)
324 {
325 	struct pps_device *pps = dev_get_drvdata(dev);
326 
327 	cdev_del(&pps->cdev);
328 
329 	/* Now we can release the ID for re-use */
330 	pr_debug("deallocating pps%d\n", pps->id);
331 	mutex_lock(&pps_idr_lock);
332 	idr_remove(&pps_idr, pps->id);
333 	mutex_unlock(&pps_idr_lock);
334 
335 	kfree(dev);
336 	kfree(pps);
337 }
338 
339 int pps_register_cdev(struct pps_device *pps)
340 {
341 	int err;
342 	dev_t devt;
343 
344 	mutex_lock(&pps_idr_lock);
345 	/*
346 	 * Get new ID for the new PPS source.  After idr_alloc() calling
347 	 * the new source will be freely available into the kernel.
348 	 */
349 	err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
350 	if (err < 0) {
351 		if (err == -ENOSPC) {
352 			pr_err("%s: too many PPS sources in the system\n",
353 			       pps->info.name);
354 			err = -EBUSY;
355 		}
356 		goto out_unlock;
357 	}
358 	pps->id = err;
359 	mutex_unlock(&pps_idr_lock);
360 
361 	devt = MKDEV(MAJOR(pps_devt), pps->id);
362 
363 	cdev_init(&pps->cdev, &pps_cdev_fops);
364 	pps->cdev.owner = pps->info.owner;
365 
366 	err = cdev_add(&pps->cdev, devt, 1);
367 	if (err) {
368 		pr_err("%s: failed to add char device %d:%d\n",
369 				pps->info.name, MAJOR(pps_devt), pps->id);
370 		goto free_idr;
371 	}
372 	pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
373 							"pps%d", pps->id);
374 	if (IS_ERR(pps->dev)) {
375 		err = PTR_ERR(pps->dev);
376 		goto del_cdev;
377 	}
378 
379 	/* Override the release function with our own */
380 	pps->dev->release = pps_device_destruct;
381 
382 	pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
383 			MAJOR(pps_devt), pps->id);
384 
385 	return 0;
386 
387 del_cdev:
388 	cdev_del(&pps->cdev);
389 
390 free_idr:
391 	mutex_lock(&pps_idr_lock);
392 	idr_remove(&pps_idr, pps->id);
393 out_unlock:
394 	mutex_unlock(&pps_idr_lock);
395 	return err;
396 }
397 
398 void pps_unregister_cdev(struct pps_device *pps)
399 {
400 	pr_debug("unregistering pps%d\n", pps->id);
401 	pps->lookup_cookie = NULL;
402 	device_destroy(pps_class, pps->dev->devt);
403 }
404 
405 /*
406  * Look up a pps device by magic cookie.
407  * The cookie is usually a pointer to some enclosing device, but this
408  * code doesn't care; you should never be dereferencing it.
409  *
410  * This is a bit of a kludge that is currently used only by the PPS
411  * serial line discipline.  It may need to be tweaked when a second user
412  * is found.
413  *
414  * There is no function interface for setting the lookup_cookie field.
415  * It's initialized to NULL when the pps device is created, and if a
416  * client wants to use it, just fill it in afterward.
417  *
418  * The cookie is automatically set to NULL in pps_unregister_source()
419  * so that it will not be used again, even if the pps device cannot
420  * be removed from the idr due to pending references holding the minor
421  * number in use.
422  */
423 struct pps_device *pps_lookup_dev(void const *cookie)
424 {
425 	struct pps_device *pps;
426 	unsigned id;
427 
428 	rcu_read_lock();
429 	idr_for_each_entry(&pps_idr, pps, id)
430 		if (cookie == pps->lookup_cookie)
431 			break;
432 	rcu_read_unlock();
433 	return pps;
434 }
435 EXPORT_SYMBOL(pps_lookup_dev);
436 
437 /*
438  * Module stuff
439  */
440 
441 static void __exit pps_exit(void)
442 {
443 	class_destroy(pps_class);
444 	unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
445 }
446 
447 static int __init pps_init(void)
448 {
449 	int err;
450 
451 	pps_class = class_create(THIS_MODULE, "pps");
452 	if (IS_ERR(pps_class)) {
453 		pr_err("failed to allocate class\n");
454 		return PTR_ERR(pps_class);
455 	}
456 	pps_class->dev_groups = pps_groups;
457 
458 	err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
459 	if (err < 0) {
460 		pr_err("failed to allocate char device region\n");
461 		goto remove_class;
462 	}
463 
464 	pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
465 	pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
466 		"<giometti@linux.it>\n", PPS_VERSION);
467 
468 	return 0;
469 
470 remove_class:
471 	class_destroy(pps_class);
472 
473 	return err;
474 }
475 
476 subsys_initcall(pps_init);
477 module_exit(pps_exit);
478 
479 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
480 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
481 MODULE_LICENSE("GPL");
482