xref: /openbmc/linux/drivers/pps/pps.c (revision 293d5b43) 
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 long pps_cdev_ioctl(struct file *file,
68 		unsigned int cmd, unsigned long arg)
69 {
70 	struct pps_device *pps = file->private_data;
71 	struct pps_kparams params;
72 	void __user *uarg = (void __user *) arg;
73 	int __user *iuarg = (int __user *) arg;
74 	int err;
75 
76 	switch (cmd) {
77 	case PPS_GETPARAMS:
78 		dev_dbg(pps->dev, "PPS_GETPARAMS\n");
79 
80 		spin_lock_irq(&pps->lock);
81 
82 		/* Get the current parameters */
83 		params = pps->params;
84 
85 		spin_unlock_irq(&pps->lock);
86 
87 		err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
88 		if (err)
89 			return -EFAULT;
90 
91 		break;
92 
93 	case PPS_SETPARAMS:
94 		dev_dbg(pps->dev, "PPS_SETPARAMS\n");
95 
96 		/* Check the capabilities */
97 		if (!capable(CAP_SYS_TIME))
98 			return -EPERM;
99 
100 		err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
101 		if (err)
102 			return -EFAULT;
103 		if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
104 			dev_dbg(pps->dev, "capture mode unspecified (%x)\n",
105 								params.mode);
106 			return -EINVAL;
107 		}
108 
109 		/* Check for supported capabilities */
110 		if ((params.mode & ~pps->info.mode) != 0) {
111 			dev_dbg(pps->dev, "unsupported capabilities (%x)\n",
112 								params.mode);
113 			return -EINVAL;
114 		}
115 
116 		spin_lock_irq(&pps->lock);
117 
118 		/* Save the new parameters */
119 		pps->params = params;
120 
121 		/* Restore the read only parameters */
122 		if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
123 			/* section 3.3 of RFC 2783 interpreted */
124 			dev_dbg(pps->dev, "time format unspecified (%x)\n",
125 								params.mode);
126 			pps->params.mode |= PPS_TSFMT_TSPEC;
127 		}
128 		if (pps->info.mode & PPS_CANWAIT)
129 			pps->params.mode |= PPS_CANWAIT;
130 		pps->params.api_version = PPS_API_VERS;
131 
132 		spin_unlock_irq(&pps->lock);
133 
134 		break;
135 
136 	case PPS_GETCAP:
137 		dev_dbg(pps->dev, "PPS_GETCAP\n");
138 
139 		err = put_user(pps->info.mode, iuarg);
140 		if (err)
141 			return -EFAULT;
142 
143 		break;
144 
145 	case PPS_FETCH: {
146 		struct pps_fdata fdata;
147 		unsigned int ev;
148 
149 		dev_dbg(pps->dev, "PPS_FETCH\n");
150 
151 		err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
152 		if (err)
153 			return -EFAULT;
154 
155 		ev = pps->last_ev;
156 
157 		/* Manage the timeout */
158 		if (fdata.timeout.flags & PPS_TIME_INVALID)
159 			err = wait_event_interruptible(pps->queue,
160 					ev != pps->last_ev);
161 		else {
162 			unsigned long ticks;
163 
164 			dev_dbg(pps->dev, "timeout %lld.%09d\n",
165 					(long long) fdata.timeout.sec,
166 					fdata.timeout.nsec);
167 			ticks = fdata.timeout.sec * HZ;
168 			ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
169 
170 			if (ticks != 0) {
171 				err = wait_event_interruptible_timeout(
172 						pps->queue,
173 						ev != pps->last_ev,
174 						ticks);
175 				if (err == 0)
176 					return -ETIMEDOUT;
177 			}
178 		}
179 
180 		/* Check for pending signals */
181 		if (err == -ERESTARTSYS) {
182 			dev_dbg(pps->dev, "pending signal caught\n");
183 			return -EINTR;
184 		}
185 
186 		/* Return the fetched timestamp */
187 		spin_lock_irq(&pps->lock);
188 
189 		fdata.info.assert_sequence = pps->assert_sequence;
190 		fdata.info.clear_sequence = pps->clear_sequence;
191 		fdata.info.assert_tu = pps->assert_tu;
192 		fdata.info.clear_tu = pps->clear_tu;
193 		fdata.info.current_mode = pps->current_mode;
194 
195 		spin_unlock_irq(&pps->lock);
196 
197 		err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
198 		if (err)
199 			return -EFAULT;
200 
201 		break;
202 	}
203 	case PPS_KC_BIND: {
204 		struct pps_bind_args bind_args;
205 
206 		dev_dbg(pps->dev, "PPS_KC_BIND\n");
207 
208 		/* Check the capabilities */
209 		if (!capable(CAP_SYS_TIME))
210 			return -EPERM;
211 
212 		if (copy_from_user(&bind_args, uarg,
213 					sizeof(struct pps_bind_args)))
214 			return -EFAULT;
215 
216 		/* Check for supported capabilities */
217 		if ((bind_args.edge & ~pps->info.mode) != 0) {
218 			dev_err(pps->dev, "unsupported capabilities (%x)\n",
219 					bind_args.edge);
220 			return -EINVAL;
221 		}
222 
223 		/* Validate parameters roughly */
224 		if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
225 				(bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
226 				bind_args.consumer != PPS_KC_HARDPPS) {
227 			dev_err(pps->dev, "invalid kernel consumer bind"
228 					" parameters (%x)\n", bind_args.edge);
229 			return -EINVAL;
230 		}
231 
232 		err = pps_kc_bind(pps, &bind_args);
233 		if (err < 0)
234 			return err;
235 
236 		break;
237 	}
238 	default:
239 		return -ENOTTY;
240 	}
241 
242 	return 0;
243 }
244 
245 static int pps_cdev_open(struct inode *inode, struct file *file)
246 {
247 	struct pps_device *pps = container_of(inode->i_cdev,
248 						struct pps_device, cdev);
249 	file->private_data = pps;
250 	kobject_get(&pps->dev->kobj);
251 	return 0;
252 }
253 
254 static int pps_cdev_release(struct inode *inode, struct file *file)
255 {
256 	struct pps_device *pps = container_of(inode->i_cdev,
257 						struct pps_device, cdev);
258 	kobject_put(&pps->dev->kobj);
259 	return 0;
260 }
261 
262 /*
263  * Char device stuff
264  */
265 
266 static const struct file_operations pps_cdev_fops = {
267 	.owner		= THIS_MODULE,
268 	.llseek		= no_llseek,
269 	.poll		= pps_cdev_poll,
270 	.fasync		= pps_cdev_fasync,
271 	.unlocked_ioctl	= pps_cdev_ioctl,
272 	.open		= pps_cdev_open,
273 	.release	= pps_cdev_release,
274 };
275 
276 static void pps_device_destruct(struct device *dev)
277 {
278 	struct pps_device *pps = dev_get_drvdata(dev);
279 
280 	cdev_del(&pps->cdev);
281 
282 	/* Now we can release the ID for re-use */
283 	pr_debug("deallocating pps%d\n", pps->id);
284 	mutex_lock(&pps_idr_lock);
285 	idr_remove(&pps_idr, pps->id);
286 	mutex_unlock(&pps_idr_lock);
287 
288 	kfree(dev);
289 	kfree(pps);
290 }
291 
292 int pps_register_cdev(struct pps_device *pps)
293 {
294 	int err;
295 	dev_t devt;
296 
297 	mutex_lock(&pps_idr_lock);
298 	/*
299 	 * Get new ID for the new PPS source.  After idr_alloc() calling
300 	 * the new source will be freely available into the kernel.
301 	 */
302 	err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
303 	if (err < 0) {
304 		if (err == -ENOSPC) {
305 			pr_err("%s: too many PPS sources in the system\n",
306 			       pps->info.name);
307 			err = -EBUSY;
308 		}
309 		goto out_unlock;
310 	}
311 	pps->id = err;
312 	mutex_unlock(&pps_idr_lock);
313 
314 	devt = MKDEV(MAJOR(pps_devt), pps->id);
315 
316 	cdev_init(&pps->cdev, &pps_cdev_fops);
317 	pps->cdev.owner = pps->info.owner;
318 
319 	err = cdev_add(&pps->cdev, devt, 1);
320 	if (err) {
321 		pr_err("%s: failed to add char device %d:%d\n",
322 				pps->info.name, MAJOR(pps_devt), pps->id);
323 		goto free_idr;
324 	}
325 	pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
326 							"pps%d", pps->id);
327 	if (IS_ERR(pps->dev)) {
328 		err = PTR_ERR(pps->dev);
329 		goto del_cdev;
330 	}
331 
332 	/* Override the release function with our own */
333 	pps->dev->release = pps_device_destruct;
334 
335 	pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
336 			MAJOR(pps_devt), pps->id);
337 
338 	return 0;
339 
340 del_cdev:
341 	cdev_del(&pps->cdev);
342 
343 free_idr:
344 	mutex_lock(&pps_idr_lock);
345 	idr_remove(&pps_idr, pps->id);
346 out_unlock:
347 	mutex_unlock(&pps_idr_lock);
348 	return err;
349 }
350 
351 void pps_unregister_cdev(struct pps_device *pps)
352 {
353 	pr_debug("unregistering pps%d\n", pps->id);
354 	pps->lookup_cookie = NULL;
355 	device_destroy(pps_class, pps->dev->devt);
356 }
357 
358 /*
359  * Look up a pps device by magic cookie.
360  * The cookie is usually a pointer to some enclosing device, but this
361  * code doesn't care; you should never be dereferencing it.
362  *
363  * This is a bit of a kludge that is currently used only by the PPS
364  * serial line discipline.  It may need to be tweaked when a second user
365  * is found.
366  *
367  * There is no function interface for setting the lookup_cookie field.
368  * It's initialized to NULL when the pps device is created, and if a
369  * client wants to use it, just fill it in afterward.
370  *
371  * The cookie is automatically set to NULL in pps_unregister_source()
372  * so that it will not be used again, even if the pps device cannot
373  * be removed from the idr due to pending references holding the minor
374  * number in use.
375  */
376 struct pps_device *pps_lookup_dev(void const *cookie)
377 {
378 	struct pps_device *pps;
379 	unsigned id;
380 
381 	rcu_read_lock();
382 	idr_for_each_entry(&pps_idr, pps, id)
383 		if (cookie == pps->lookup_cookie)
384 			break;
385 	rcu_read_unlock();
386 	return pps;
387 }
388 EXPORT_SYMBOL(pps_lookup_dev);
389 
390 /*
391  * Module stuff
392  */
393 
394 static void __exit pps_exit(void)
395 {
396 	class_destroy(pps_class);
397 	unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
398 }
399 
400 static int __init pps_init(void)
401 {
402 	int err;
403 
404 	pps_class = class_create(THIS_MODULE, "pps");
405 	if (IS_ERR(pps_class)) {
406 		pr_err("failed to allocate class\n");
407 		return PTR_ERR(pps_class);
408 	}
409 	pps_class->dev_groups = pps_groups;
410 
411 	err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
412 	if (err < 0) {
413 		pr_err("failed to allocate char device region\n");
414 		goto remove_class;
415 	}
416 
417 	pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
418 	pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
419 		"<giometti@linux.it>\n", PPS_VERSION);
420 
421 	return 0;
422 
423 remove_class:
424 	class_destroy(pps_class);
425 
426 	return err;
427 }
428 
429 subsys_initcall(pps_init);
430 module_exit(pps_exit);
431 
432 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
433 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
434 MODULE_LICENSE("GPL");
435