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
pps_cdev_poll(struct file * file,poll_table * wait)52 static __poll_t 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 EPOLLIN | EPOLLRDNORM;
59 }
60
pps_cdev_fasync(int fd,struct file * file,int on)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
pps_cdev_pps_fetch(struct pps_device * pps,struct pps_fdata * fdata)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
pps_cdev_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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, ¶ms, 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(¶ms, 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 /*
170 * Clear unused fields of pps_kparams to avoid leaking
171 * uninitialized data of the PPS_SETPARAMS caller via
172 * PPS_GETPARAMS
173 */
174 pps->params.assert_off_tu.flags = 0;
175 pps->params.clear_off_tu.flags = 0;
176
177 spin_unlock_irq(&pps->lock);
178
179 break;
180
181 case PPS_GETCAP:
182 dev_dbg(pps->dev, "PPS_GETCAP\n");
183
184 err = put_user(pps->info.mode, iuarg);
185 if (err)
186 return -EFAULT;
187
188 break;
189
190 case PPS_FETCH: {
191 struct pps_fdata fdata;
192
193 dev_dbg(pps->dev, "PPS_FETCH\n");
194
195 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
196 if (err)
197 return -EFAULT;
198
199 err = pps_cdev_pps_fetch(pps, &fdata);
200 if (err)
201 return err;
202
203 /* Return the fetched timestamp */
204 spin_lock_irq(&pps->lock);
205
206 fdata.info.assert_sequence = pps->assert_sequence;
207 fdata.info.clear_sequence = pps->clear_sequence;
208 fdata.info.assert_tu = pps->assert_tu;
209 fdata.info.clear_tu = pps->clear_tu;
210 fdata.info.current_mode = pps->current_mode;
211
212 spin_unlock_irq(&pps->lock);
213
214 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
215 if (err)
216 return -EFAULT;
217
218 break;
219 }
220 case PPS_KC_BIND: {
221 struct pps_bind_args bind_args;
222
223 dev_dbg(pps->dev, "PPS_KC_BIND\n");
224
225 /* Check the capabilities */
226 if (!capable(CAP_SYS_TIME))
227 return -EPERM;
228
229 if (copy_from_user(&bind_args, uarg,
230 sizeof(struct pps_bind_args)))
231 return -EFAULT;
232
233 /* Check for supported capabilities */
234 if ((bind_args.edge & ~pps->info.mode) != 0) {
235 dev_err(pps->dev, "unsupported capabilities (%x)\n",
236 bind_args.edge);
237 return -EINVAL;
238 }
239
240 /* Validate parameters roughly */
241 if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
242 (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
243 bind_args.consumer != PPS_KC_HARDPPS) {
244 dev_err(pps->dev, "invalid kernel consumer bind"
245 " parameters (%x)\n", bind_args.edge);
246 return -EINVAL;
247 }
248
249 err = pps_kc_bind(pps, &bind_args);
250 if (err < 0)
251 return err;
252
253 break;
254 }
255 default:
256 return -ENOTTY;
257 }
258
259 return 0;
260 }
261
262 #ifdef CONFIG_COMPAT
pps_cdev_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)263 static long pps_cdev_compat_ioctl(struct file *file,
264 unsigned int cmd, unsigned long arg)
265 {
266 struct pps_device *pps = file->private_data;
267 void __user *uarg = (void __user *) arg;
268
269 cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
270
271 if (cmd == PPS_FETCH) {
272 struct pps_fdata_compat compat;
273 struct pps_fdata fdata;
274 int err;
275
276 dev_dbg(pps->dev, "PPS_FETCH\n");
277
278 err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
279 if (err)
280 return -EFAULT;
281
282 memcpy(&fdata.timeout, &compat.timeout,
283 sizeof(struct pps_ktime_compat));
284
285 err = pps_cdev_pps_fetch(pps, &fdata);
286 if (err)
287 return err;
288
289 /* Return the fetched timestamp */
290 spin_lock_irq(&pps->lock);
291
292 compat.info.assert_sequence = pps->assert_sequence;
293 compat.info.clear_sequence = pps->clear_sequence;
294 compat.info.current_mode = pps->current_mode;
295
296 memcpy(&compat.info.assert_tu, &pps->assert_tu,
297 sizeof(struct pps_ktime_compat));
298 memcpy(&compat.info.clear_tu, &pps->clear_tu,
299 sizeof(struct pps_ktime_compat));
300
301 spin_unlock_irq(&pps->lock);
302
303 return copy_to_user(uarg, &compat,
304 sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
305 }
306
307 return pps_cdev_ioctl(file, cmd, arg);
308 }
309 #else
310 #define pps_cdev_compat_ioctl NULL
311 #endif
312
pps_cdev_open(struct inode * inode,struct file * file)313 static int pps_cdev_open(struct inode *inode, struct file *file)
314 {
315 struct pps_device *pps = container_of(inode->i_cdev,
316 struct pps_device, cdev);
317 file->private_data = pps;
318 kobject_get(&pps->dev->kobj);
319 return 0;
320 }
321
pps_cdev_release(struct inode * inode,struct file * file)322 static int pps_cdev_release(struct inode *inode, struct file *file)
323 {
324 struct pps_device *pps = container_of(inode->i_cdev,
325 struct pps_device, cdev);
326 kobject_put(&pps->dev->kobj);
327 return 0;
328 }
329
330 /*
331 * Char device stuff
332 */
333
334 static const struct file_operations pps_cdev_fops = {
335 .owner = THIS_MODULE,
336 .llseek = no_llseek,
337 .poll = pps_cdev_poll,
338 .fasync = pps_cdev_fasync,
339 .compat_ioctl = pps_cdev_compat_ioctl,
340 .unlocked_ioctl = pps_cdev_ioctl,
341 .open = pps_cdev_open,
342 .release = pps_cdev_release,
343 };
344
pps_device_destruct(struct device * dev)345 static void pps_device_destruct(struct device *dev)
346 {
347 struct pps_device *pps = dev_get_drvdata(dev);
348
349 cdev_del(&pps->cdev);
350
351 /* Now we can release the ID for re-use */
352 pr_debug("deallocating pps%d\n", pps->id);
353 mutex_lock(&pps_idr_lock);
354 idr_remove(&pps_idr, pps->id);
355 mutex_unlock(&pps_idr_lock);
356
357 kfree(dev);
358 kfree(pps);
359 }
360
pps_register_cdev(struct pps_device * pps)361 int pps_register_cdev(struct pps_device *pps)
362 {
363 int err;
364 dev_t devt;
365
366 mutex_lock(&pps_idr_lock);
367 /*
368 * Get new ID for the new PPS source. After idr_alloc() calling
369 * the new source will be freely available into the kernel.
370 */
371 err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
372 if (err < 0) {
373 if (err == -ENOSPC) {
374 pr_err("%s: too many PPS sources in the system\n",
375 pps->info.name);
376 err = -EBUSY;
377 }
378 goto out_unlock;
379 }
380 pps->id = err;
381 mutex_unlock(&pps_idr_lock);
382
383 devt = MKDEV(MAJOR(pps_devt), pps->id);
384
385 cdev_init(&pps->cdev, &pps_cdev_fops);
386 pps->cdev.owner = pps->info.owner;
387
388 err = cdev_add(&pps->cdev, devt, 1);
389 if (err) {
390 pr_err("%s: failed to add char device %d:%d\n",
391 pps->info.name, MAJOR(pps_devt), pps->id);
392 goto free_idr;
393 }
394 pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
395 "pps%d", pps->id);
396 if (IS_ERR(pps->dev)) {
397 err = PTR_ERR(pps->dev);
398 goto del_cdev;
399 }
400
401 /* Override the release function with our own */
402 pps->dev->release = pps_device_destruct;
403
404 pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
405 MAJOR(pps_devt), pps->id);
406
407 return 0;
408
409 del_cdev:
410 cdev_del(&pps->cdev);
411
412 free_idr:
413 mutex_lock(&pps_idr_lock);
414 idr_remove(&pps_idr, pps->id);
415 out_unlock:
416 mutex_unlock(&pps_idr_lock);
417 return err;
418 }
419
pps_unregister_cdev(struct pps_device * pps)420 void pps_unregister_cdev(struct pps_device *pps)
421 {
422 pr_debug("unregistering pps%d\n", pps->id);
423 pps->lookup_cookie = NULL;
424 device_destroy(pps_class, pps->dev->devt);
425 }
426
427 /*
428 * Look up a pps device by magic cookie.
429 * The cookie is usually a pointer to some enclosing device, but this
430 * code doesn't care; you should never be dereferencing it.
431 *
432 * This is a bit of a kludge that is currently used only by the PPS
433 * serial line discipline. It may need to be tweaked when a second user
434 * is found.
435 *
436 * There is no function interface for setting the lookup_cookie field.
437 * It's initialized to NULL when the pps device is created, and if a
438 * client wants to use it, just fill it in afterward.
439 *
440 * The cookie is automatically set to NULL in pps_unregister_source()
441 * so that it will not be used again, even if the pps device cannot
442 * be removed from the idr due to pending references holding the minor
443 * number in use.
444 */
pps_lookup_dev(void const * cookie)445 struct pps_device *pps_lookup_dev(void const *cookie)
446 {
447 struct pps_device *pps;
448 unsigned id;
449
450 rcu_read_lock();
451 idr_for_each_entry(&pps_idr, pps, id)
452 if (cookie == pps->lookup_cookie)
453 break;
454 rcu_read_unlock();
455 return pps;
456 }
457 EXPORT_SYMBOL(pps_lookup_dev);
458
459 /*
460 * Module stuff
461 */
462
pps_exit(void)463 static void __exit pps_exit(void)
464 {
465 class_destroy(pps_class);
466 unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
467 }
468
pps_init(void)469 static int __init pps_init(void)
470 {
471 int err;
472
473 pps_class = class_create(THIS_MODULE, "pps");
474 if (IS_ERR(pps_class)) {
475 pr_err("failed to allocate class\n");
476 return PTR_ERR(pps_class);
477 }
478 pps_class->dev_groups = pps_groups;
479
480 err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
481 if (err < 0) {
482 pr_err("failed to allocate char device region\n");
483 goto remove_class;
484 }
485
486 pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
487 pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
488 "<giometti@linux.it>\n", PPS_VERSION);
489
490 return 0;
491
492 remove_class:
493 class_destroy(pps_class);
494
495 return err;
496 }
497
498 subsys_initcall(pps_init);
499 module_exit(pps_exit);
500
501 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
502 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
503 MODULE_LICENSE("GPL");
504