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 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
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_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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, ¶ms, 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(¶ms, 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 /*
133 * Clear unused fields of pps_kparams to avoid leaking
134 * uninitialized data of the PPS_SETPARAMS caller via
135 * PPS_GETPARAMS
136 */
137 pps->params.assert_off_tu.flags = 0;
138 pps->params.clear_off_tu.flags = 0;
139
140 spin_unlock_irq(&pps->lock);
141
142 break;
143
144 case PPS_GETCAP:
145 dev_dbg(pps->dev, "PPS_GETCAP\n");
146
147 err = put_user(pps->info.mode, iuarg);
148 if (err)
149 return -EFAULT;
150
151 break;
152
153 case PPS_FETCH: {
154 struct pps_fdata fdata;
155 unsigned int ev;
156
157 dev_dbg(pps->dev, "PPS_FETCH\n");
158
159 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
160 if (err)
161 return -EFAULT;
162
163 ev = pps->last_ev;
164
165 /* Manage the timeout */
166 if (fdata.timeout.flags & PPS_TIME_INVALID)
167 err = wait_event_interruptible(pps->queue,
168 ev != pps->last_ev);
169 else {
170 unsigned long ticks;
171
172 dev_dbg(pps->dev, "timeout %lld.%09d\n",
173 (long long) fdata.timeout.sec,
174 fdata.timeout.nsec);
175 ticks = fdata.timeout.sec * HZ;
176 ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
177
178 if (ticks != 0) {
179 err = wait_event_interruptible_timeout(
180 pps->queue,
181 ev != pps->last_ev,
182 ticks);
183 if (err == 0)
184 return -ETIMEDOUT;
185 }
186 }
187
188 /* Check for pending signals */
189 if (err == -ERESTARTSYS) {
190 dev_dbg(pps->dev, "pending signal caught\n");
191 return -EINTR;
192 }
193
194 /* Return the fetched timestamp */
195 spin_lock_irq(&pps->lock);
196
197 fdata.info.assert_sequence = pps->assert_sequence;
198 fdata.info.clear_sequence = pps->clear_sequence;
199 fdata.info.assert_tu = pps->assert_tu;
200 fdata.info.clear_tu = pps->clear_tu;
201 fdata.info.current_mode = pps->current_mode;
202
203 spin_unlock_irq(&pps->lock);
204
205 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
206 if (err)
207 return -EFAULT;
208
209 break;
210 }
211 case PPS_KC_BIND: {
212 struct pps_bind_args bind_args;
213
214 dev_dbg(pps->dev, "PPS_KC_BIND\n");
215
216 /* Check the capabilities */
217 if (!capable(CAP_SYS_TIME))
218 return -EPERM;
219
220 if (copy_from_user(&bind_args, uarg,
221 sizeof(struct pps_bind_args)))
222 return -EFAULT;
223
224 /* Check for supported capabilities */
225 if ((bind_args.edge & ~pps->info.mode) != 0) {
226 dev_err(pps->dev, "unsupported capabilities (%x)\n",
227 bind_args.edge);
228 return -EINVAL;
229 }
230
231 /* Validate parameters roughly */
232 if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
233 (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
234 bind_args.consumer != PPS_KC_HARDPPS) {
235 dev_err(pps->dev, "invalid kernel consumer bind"
236 " parameters (%x)\n", bind_args.edge);
237 return -EINVAL;
238 }
239
240 err = pps_kc_bind(pps, &bind_args);
241 if (err < 0)
242 return err;
243
244 break;
245 }
246 default:
247 return -ENOTTY;
248 }
249
250 return 0;
251 }
252
pps_cdev_open(struct inode * inode,struct file * file)253 static int pps_cdev_open(struct inode *inode, struct file *file)
254 {
255 struct pps_device *pps = container_of(inode->i_cdev,
256 struct pps_device, cdev);
257 file->private_data = pps;
258 kobject_get(&pps->dev->kobj);
259 return 0;
260 }
261
pps_cdev_release(struct inode * inode,struct file * file)262 static int pps_cdev_release(struct inode *inode, struct file *file)
263 {
264 struct pps_device *pps = container_of(inode->i_cdev,
265 struct pps_device, cdev);
266 kobject_put(&pps->dev->kobj);
267 return 0;
268 }
269
270 /*
271 * Char device stuff
272 */
273
274 static const struct file_operations pps_cdev_fops = {
275 .owner = THIS_MODULE,
276 .llseek = no_llseek,
277 .poll = pps_cdev_poll,
278 .fasync = pps_cdev_fasync,
279 .unlocked_ioctl = pps_cdev_ioctl,
280 .open = pps_cdev_open,
281 .release = pps_cdev_release,
282 };
283
pps_device_destruct(struct device * dev)284 static void pps_device_destruct(struct device *dev)
285 {
286 struct pps_device *pps = dev_get_drvdata(dev);
287
288 cdev_del(&pps->cdev);
289
290 /* Now we can release the ID for re-use */
291 pr_debug("deallocating pps%d\n", pps->id);
292 mutex_lock(&pps_idr_lock);
293 idr_remove(&pps_idr, pps->id);
294 mutex_unlock(&pps_idr_lock);
295
296 kfree(dev);
297 kfree(pps);
298 }
299
pps_register_cdev(struct pps_device * pps)300 int pps_register_cdev(struct pps_device *pps)
301 {
302 int err;
303 dev_t devt;
304
305 mutex_lock(&pps_idr_lock);
306 /*
307 * Get new ID for the new PPS source. After idr_alloc() calling
308 * the new source will be freely available into the kernel.
309 */
310 err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL);
311 if (err < 0) {
312 if (err == -ENOSPC) {
313 pr_err("%s: too many PPS sources in the system\n",
314 pps->info.name);
315 err = -EBUSY;
316 }
317 goto out_unlock;
318 }
319 pps->id = err;
320 mutex_unlock(&pps_idr_lock);
321
322 devt = MKDEV(MAJOR(pps_devt), pps->id);
323
324 cdev_init(&pps->cdev, &pps_cdev_fops);
325 pps->cdev.owner = pps->info.owner;
326
327 err = cdev_add(&pps->cdev, devt, 1);
328 if (err) {
329 pr_err("%s: failed to add char device %d:%d\n",
330 pps->info.name, MAJOR(pps_devt), pps->id);
331 goto free_idr;
332 }
333 pps->dev = device_create(pps_class, pps->info.dev, devt, pps,
334 "pps%d", pps->id);
335 if (IS_ERR(pps->dev)) {
336 err = PTR_ERR(pps->dev);
337 goto del_cdev;
338 }
339
340 /* Override the release function with our own */
341 pps->dev->release = pps_device_destruct;
342
343 pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
344 MAJOR(pps_devt), pps->id);
345
346 return 0;
347
348 del_cdev:
349 cdev_del(&pps->cdev);
350
351 free_idr:
352 mutex_lock(&pps_idr_lock);
353 idr_remove(&pps_idr, pps->id);
354 out_unlock:
355 mutex_unlock(&pps_idr_lock);
356 return err;
357 }
358
pps_unregister_cdev(struct pps_device * pps)359 void pps_unregister_cdev(struct pps_device *pps)
360 {
361 pr_debug("unregistering pps%d\n", pps->id);
362 pps->lookup_cookie = NULL;
363 device_destroy(pps_class, pps->dev->devt);
364 }
365
366 /*
367 * Look up a pps device by magic cookie.
368 * The cookie is usually a pointer to some enclosing device, but this
369 * code doesn't care; you should never be dereferencing it.
370 *
371 * This is a bit of a kludge that is currently used only by the PPS
372 * serial line discipline. It may need to be tweaked when a second user
373 * is found.
374 *
375 * There is no function interface for setting the lookup_cookie field.
376 * It's initialized to NULL when the pps device is created, and if a
377 * client wants to use it, just fill it in afterward.
378 *
379 * The cookie is automatically set to NULL in pps_unregister_source()
380 * so that it will not be used again, even if the pps device cannot
381 * be removed from the idr due to pending references holding the minor
382 * number in use.
383 */
pps_lookup_dev(void const * cookie)384 struct pps_device *pps_lookup_dev(void const *cookie)
385 {
386 struct pps_device *pps;
387 unsigned id;
388
389 rcu_read_lock();
390 idr_for_each_entry(&pps_idr, pps, id)
391 if (cookie == pps->lookup_cookie)
392 break;
393 rcu_read_unlock();
394 return pps;
395 }
396 EXPORT_SYMBOL(pps_lookup_dev);
397
398 /*
399 * Module stuff
400 */
401
pps_exit(void)402 static void __exit pps_exit(void)
403 {
404 class_destroy(pps_class);
405 unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
406 }
407
pps_init(void)408 static int __init pps_init(void)
409 {
410 int err;
411
412 pps_class = class_create(THIS_MODULE, "pps");
413 if (IS_ERR(pps_class)) {
414 pr_err("failed to allocate class\n");
415 return PTR_ERR(pps_class);
416 }
417 pps_class->dev_groups = pps_groups;
418
419 err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
420 if (err < 0) {
421 pr_err("failed to allocate char device region\n");
422 goto remove_class;
423 }
424
425 pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
426 pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
427 "<giometti@linux.it>\n", PPS_VERSION);
428
429 return 0;
430
431 remove_class:
432 class_destroy(pps_class);
433
434 return err;
435 }
436
437 subsys_initcall(pps_init);
438 module_exit(pps_exit);
439
440 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
441 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
442 MODULE_LICENSE("GPL");
443