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
28static int pps_major;
29static struct class *pps_class;
30
31static DEFINE_MUTEX(pps_idr_lock);
32static DEFINE_IDR(pps_idr);
33
34/*
35 * Char device methods
36 */
37
38static __poll_t pps_cdev_poll(struct file *file, poll_table *wait)
39{
40 struct pps_device *pps = file->private_data;
41
42 poll_wait(filp: file, wait_address: &pps->queue, p: wait);
43
44 if (pps->last_fetched_ev == pps->last_ev)
45 return 0;
46
47 return EPOLLIN | EPOLLRDNORM;
48}
49
50static int pps_cdev_fasync(int fd, struct file *file, int on)
51{
52 struct pps_device *pps = file->private_data;
53 return fasync_helper(fd, file, on, &pps->async_queue);
54}
55
56static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
57{
58 unsigned int ev = pps->last_ev;
59 int err = 0;
60
61 /* Manage the timeout */
62 if (fdata->timeout.flags & PPS_TIME_INVALID)
63 err = wait_event_interruptible(pps->queue,
64 ev != pps->last_ev);
65 else {
66 unsigned long ticks;
67
68 dev_dbg(&pps->dev, "timeout %lld.%09d\n",
69 (long long) fdata->timeout.sec,
70 fdata->timeout.nsec);
71 ticks = fdata->timeout.sec * HZ;
72 ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ);
73
74 if (ticks != 0) {
75 err = wait_event_interruptible_timeout(
76 pps->queue,
77 ev != pps->last_ev,
78 ticks);
79 if (err == 0)
80 return -ETIMEDOUT;
81 }
82 }
83
84 /* Check for pending signals */
85 if (err == -ERESTARTSYS) {
86 dev_dbg(&pps->dev, "pending signal caught\n");
87 return -EINTR;
88 }
89
90 return 0;
91}
92
93static long pps_cdev_ioctl(struct file *file,
94 unsigned int cmd, unsigned long arg)
95{
96 struct pps_device *pps = file->private_data;
97 struct pps_kparams params;
98 void __user *uarg = (void __user *) arg;
99 int __user *iuarg = (int __user *) arg;
100 int err;
101
102 switch (cmd) {
103 case PPS_GETPARAMS:
104 dev_dbg(&pps->dev, "PPS_GETPARAMS\n");
105
106 spin_lock_irq(lock: &pps->lock);
107
108 /* Get the current parameters */
109 params = pps->params;
110
111 spin_unlock_irq(lock: &pps->lock);
112
113 err = copy_to_user(to: uarg, from: &params, n: sizeof(struct pps_kparams));
114 if (err)
115 return -EFAULT;
116
117 break;
118
119 case PPS_SETPARAMS:
120 dev_dbg(&pps->dev, "PPS_SETPARAMS\n");
121
122 /* Check the capabilities */
123 if (!capable(CAP_SYS_TIME))
124 return -EPERM;
125
126 err = copy_from_user(to: &params, from: uarg, n: sizeof(struct pps_kparams));
127 if (err)
128 return -EFAULT;
129 if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
130 dev_dbg(&pps->dev, "capture mode unspecified (%x)\n",
131 params.mode);
132 return -EINVAL;
133 }
134
135 /* Check for supported capabilities */
136 if ((params.mode & ~pps->info.mode) != 0) {
137 dev_dbg(&pps->dev, "unsupported capabilities (%x)\n",
138 params.mode);
139 return -EINVAL;
140 }
141
142 spin_lock_irq(lock: &pps->lock);
143
144 /* Save the new parameters */
145 pps->params = params;
146
147 /* Restore the read only parameters */
148 if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
149 /* section 3.3 of RFC 2783 interpreted */
150 dev_dbg(&pps->dev, "time format unspecified (%x)\n",
151 params.mode);
152 pps->params.mode |= PPS_TSFMT_TSPEC;
153 }
154 if (pps->info.mode & PPS_CANWAIT)
155 pps->params.mode |= PPS_CANWAIT;
156 pps->params.api_version = PPS_API_VERS;
157
158 /*
159 * Clear unused fields of pps_kparams to avoid leaking
160 * uninitialized data of the PPS_SETPARAMS caller via
161 * PPS_GETPARAMS
162 */
163 pps->params.assert_off_tu.flags = 0;
164 pps->params.clear_off_tu.flags = 0;
165
166 spin_unlock_irq(lock: &pps->lock);
167
168 break;
169
170 case PPS_GETCAP:
171 dev_dbg(&pps->dev, "PPS_GETCAP\n");
172
173 err = put_user(pps->info.mode, iuarg);
174 if (err)
175 return -EFAULT;
176
177 break;
178
179 case PPS_FETCH: {
180 struct pps_fdata fdata;
181
182 dev_dbg(&pps->dev, "PPS_FETCH\n");
183
184 err = copy_from_user(to: &fdata, from: uarg, n: sizeof(struct pps_fdata));
185 if (err)
186 return -EFAULT;
187
188 err = pps_cdev_pps_fetch(pps, fdata: &fdata);
189 if (err)
190 return err;
191
192 /* Return the fetched timestamp and save last fetched event */
193 spin_lock_irq(lock: &pps->lock);
194
195 pps->last_fetched_ev = pps->last_ev;
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(lock: &pps->lock);
204
205 err = copy_to_user(to: uarg, from: &fdata, n: 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(to: &bind_args, from: uarg,
221 n: 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: &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
253#ifdef CONFIG_COMPAT
254static long pps_cdev_compat_ioctl(struct file *file,
255 unsigned int cmd, unsigned long arg)
256{
257 struct pps_device *pps = file->private_data;
258 void __user *uarg = (void __user *) arg;
259
260 cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
261
262 if (cmd == PPS_FETCH) {
263 struct pps_fdata_compat compat;
264 struct pps_fdata fdata;
265 int err;
266
267 dev_dbg(&pps->dev, "PPS_FETCH\n");
268
269 err = copy_from_user(to: &compat, from: uarg, n: sizeof(struct pps_fdata_compat));
270 if (err)
271 return -EFAULT;
272
273 memcpy(to: &fdata.timeout, from: &compat.timeout,
274 len: sizeof(struct pps_ktime_compat));
275
276 err = pps_cdev_pps_fetch(pps, fdata: &fdata);
277 if (err)
278 return err;
279
280 /* Return the fetched timestamp and save last fetched event */
281 spin_lock_irq(lock: &pps->lock);
282
283 pps->last_fetched_ev = pps->last_ev;
284
285 compat.info.assert_sequence = pps->assert_sequence;
286 compat.info.clear_sequence = pps->clear_sequence;
287 compat.info.current_mode = pps->current_mode;
288
289 memcpy(to: &compat.info.assert_tu, from: &pps->assert_tu,
290 len: sizeof(struct pps_ktime_compat));
291 memcpy(to: &compat.info.clear_tu, from: &pps->clear_tu,
292 len: sizeof(struct pps_ktime_compat));
293
294 spin_unlock_irq(lock: &pps->lock);
295
296 return copy_to_user(to: uarg, from: &compat,
297 n: sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
298 }
299
300 return pps_cdev_ioctl(file, cmd, arg);
301}
302#else
303#define pps_cdev_compat_ioctl NULL
304#endif
305
306static struct pps_device *pps_idr_get(unsigned long id)
307{
308 struct pps_device *pps;
309
310 mutex_lock(lock: &pps_idr_lock);
311 pps = idr_find(&pps_idr, id);
312 if (pps)
313 get_device(dev: &pps->dev);
314
315 mutex_unlock(lock: &pps_idr_lock);
316 return pps;
317}
318
319static int pps_cdev_open(struct inode *inode, struct file *file)
320{
321 struct pps_device *pps = pps_idr_get(id: iminor(inode));
322
323 if (!pps)
324 return -ENODEV;
325
326 file->private_data = pps;
327 return 0;
328}
329
330static int pps_cdev_release(struct inode *inode, struct file *file)
331{
332 struct pps_device *pps = file->private_data;
333
334 WARN_ON(pps->id != iminor(inode));
335 put_device(dev: &pps->dev);
336 return 0;
337}
338
339/*
340 * Char device stuff
341 */
342
343static const struct file_operations pps_cdev_fops = {
344 .owner = THIS_MODULE,
345 .poll = pps_cdev_poll,
346 .fasync = pps_cdev_fasync,
347 .compat_ioctl = pps_cdev_compat_ioctl,
348 .unlocked_ioctl = pps_cdev_ioctl,
349 .open = pps_cdev_open,
350 .release = pps_cdev_release,
351};
352
353static void pps_device_destruct(struct device *dev)
354{
355 struct pps_device *pps = dev_get_drvdata(dev);
356
357 pr_debug("deallocating pps%d\n", pps->id);
358 kfree(objp: pps);
359}
360
361int pps_register_cdev(struct pps_device *pps)
362{
363 int err;
364
365 mutex_lock(lock: &pps_idr_lock);
366 /*
367 * Get new ID for the new PPS source. After idr_alloc() calling
368 * the new source will be freely available into the kernel.
369 */
370 err = idr_alloc(&pps_idr, ptr: pps, start: 0, PPS_MAX_SOURCES, GFP_KERNEL);
371 if (err < 0) {
372 if (err == -ENOSPC) {
373 pr_err("%s: too many PPS sources in the system\n",
374 pps->info.name);
375 err = -EBUSY;
376 }
377 kfree(objp: pps);
378 goto out_unlock;
379 }
380 pps->id = err;
381
382 pps->dev.class = pps_class;
383 pps->dev.parent = pps->info.dev;
384 pps->dev.devt = MKDEV(pps_major, pps->id);
385 dev_set_drvdata(dev: &pps->dev, data: pps);
386 dev_set_name(dev: &pps->dev, name: "pps%d", pps->id);
387 pps->dev.release = pps_device_destruct;
388 err = device_register(dev: &pps->dev);
389 if (err)
390 goto free_idr;
391
392 pr_debug("source %s got cdev (%d:%d)\n", pps->info.name, pps_major,
393 pps->id);
394
395 get_device(dev: &pps->dev);
396 mutex_unlock(lock: &pps_idr_lock);
397 return 0;
398
399free_idr:
400 idr_remove(&pps_idr, id: pps->id);
401 put_device(dev: &pps->dev);
402out_unlock:
403 mutex_unlock(lock: &pps_idr_lock);
404 return err;
405}
406
407void pps_unregister_cdev(struct pps_device *pps)
408{
409 pr_debug("unregistering pps%d\n", pps->id);
410 pps->lookup_cookie = NULL;
411 device_destroy(cls: pps_class, devt: pps->dev.devt);
412
413 /* Now we can release the ID for re-use */
414 mutex_lock(lock: &pps_idr_lock);
415 idr_remove(&pps_idr, id: pps->id);
416 put_device(dev: &pps->dev);
417 mutex_unlock(lock: &pps_idr_lock);
418}
419
420/*
421 * Look up a pps device by magic cookie.
422 * The cookie is usually a pointer to some enclosing device, but this
423 * code doesn't care; you should never be dereferencing it.
424 *
425 * This is a bit of a kludge that is currently used only by the PPS
426 * serial line discipline. It may need to be tweaked when a second user
427 * is found.
428 *
429 * There is no function interface for setting the lookup_cookie field.
430 * It's initialized to NULL when the pps device is created, and if a
431 * client wants to use it, just fill it in afterward.
432 *
433 * The cookie is automatically set to NULL in pps_unregister_source()
434 * so that it will not be used again, even if the pps device cannot
435 * be removed from the idr due to pending references holding the minor
436 * number in use.
437 *
438 * Since pps_idr holds a reference to the device, the returned
439 * pps_device is guaranteed to be valid until pps_unregister_cdev() is
440 * called on it. But after calling pps_unregister_cdev(), it may be
441 * freed at any time.
442 */
443struct pps_device *pps_lookup_dev(void const *cookie)
444{
445 struct pps_device *pps;
446 unsigned id;
447
448 rcu_read_lock();
449 idr_for_each_entry(&pps_idr, pps, id)
450 if (cookie == pps->lookup_cookie)
451 break;
452 rcu_read_unlock();
453 return pps;
454}
455EXPORT_SYMBOL(pps_lookup_dev);
456
457/*
458 * Module stuff
459 */
460
461static void __exit pps_exit(void)
462{
463 class_destroy(cls: pps_class);
464 __unregister_chrdev(major: pps_major, baseminor: 0, PPS_MAX_SOURCES, name: "pps");
465}
466
467static int __init pps_init(void)
468{
469 pps_class = class_create(name: "pps");
470 if (IS_ERR(ptr: pps_class)) {
471 pr_err("failed to allocate class\n");
472 return PTR_ERR(ptr: pps_class);
473 }
474 pps_class->dev_groups = pps_groups;
475
476 pps_major = __register_chrdev(major: 0, baseminor: 0, PPS_MAX_SOURCES, name: "pps",
477 fops: &pps_cdev_fops);
478 if (pps_major < 0) {
479 pr_err("failed to allocate char device region\n");
480 goto remove_class;
481 }
482
483 pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
484 pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
485 "<giometti@linux.it>\n", PPS_VERSION);
486
487 return 0;
488
489remove_class:
490 class_destroy(cls: pps_class);
491 return pps_major;
492}
493
494subsys_initcall(pps_init);
495module_exit(pps_exit);
496
497MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
498MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
499MODULE_LICENSE("GPL");
500