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 return EPOLLIN | EPOLLRDNORM;
45}
46
47static 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
53static 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
90static 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(lock: &pps->lock);
104
105 /* Get the current parameters */
106 params = pps->params;
107
108 spin_unlock_irq(lock: &pps->lock);
109
110 err = copy_to_user(to: uarg, from: &params, n: 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(to: &params, from: uarg, n: 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(lock: &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 /*
156 * Clear unused fields of pps_kparams to avoid leaking
157 * uninitialized data of the PPS_SETPARAMS caller via
158 * PPS_GETPARAMS
159 */
160 pps->params.assert_off_tu.flags = 0;
161 pps->params.clear_off_tu.flags = 0;
162
163 spin_unlock_irq(lock: &pps->lock);
164
165 break;
166
167 case PPS_GETCAP:
168 dev_dbg(&pps->dev, "PPS_GETCAP\n");
169
170 err = put_user(pps->info.mode, iuarg);
171 if (err)
172 return -EFAULT;
173
174 break;
175
176 case PPS_FETCH: {
177 struct pps_fdata fdata;
178
179 dev_dbg(&pps->dev, "PPS_FETCH\n");
180
181 err = copy_from_user(to: &fdata, from: uarg, n: sizeof(struct pps_fdata));
182 if (err)
183 return -EFAULT;
184
185 err = pps_cdev_pps_fetch(pps, fdata: &fdata);
186 if (err)
187 return err;
188
189 /* Return the fetched timestamp */
190 spin_lock_irq(lock: &pps->lock);
191
192 fdata.info.assert_sequence = pps->assert_sequence;
193 fdata.info.clear_sequence = pps->clear_sequence;
194 fdata.info.assert_tu = pps->assert_tu;
195 fdata.info.clear_tu = pps->clear_tu;
196 fdata.info.current_mode = pps->current_mode;
197
198 spin_unlock_irq(lock: &pps->lock);
199
200 err = copy_to_user(to: uarg, from: &fdata, n: sizeof(struct pps_fdata));
201 if (err)
202 return -EFAULT;
203
204 break;
205 }
206 case PPS_KC_BIND: {
207 struct pps_bind_args bind_args;
208
209 dev_dbg(&pps->dev, "PPS_KC_BIND\n");
210
211 /* Check the capabilities */
212 if (!capable(CAP_SYS_TIME))
213 return -EPERM;
214
215 if (copy_from_user(to: &bind_args, from: uarg,
216 n: sizeof(struct pps_bind_args)))
217 return -EFAULT;
218
219 /* Check for supported capabilities */
220 if ((bind_args.edge & ~pps->info.mode) != 0) {
221 dev_err(&pps->dev, "unsupported capabilities (%x)\n",
222 bind_args.edge);
223 return -EINVAL;
224 }
225
226 /* Validate parameters roughly */
227 if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
228 (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
229 bind_args.consumer != PPS_KC_HARDPPS) {
230 dev_err(&pps->dev, "invalid kernel consumer bind"
231 " parameters (%x)\n", bind_args.edge);
232 return -EINVAL;
233 }
234
235 err = pps_kc_bind(pps, bind_args: &bind_args);
236 if (err < 0)
237 return err;
238
239 break;
240 }
241 default:
242 return -ENOTTY;
243 }
244
245 return 0;
246}
247
248#ifdef CONFIG_COMPAT
249static long pps_cdev_compat_ioctl(struct file *file,
250 unsigned int cmd, unsigned long arg)
251{
252 struct pps_device *pps = file->private_data;
253 void __user *uarg = (void __user *) arg;
254
255 cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
256
257 if (cmd == PPS_FETCH) {
258 struct pps_fdata_compat compat;
259 struct pps_fdata fdata;
260 int err;
261
262 dev_dbg(&pps->dev, "PPS_FETCH\n");
263
264 err = copy_from_user(to: &compat, from: uarg, n: sizeof(struct pps_fdata_compat));
265 if (err)
266 return -EFAULT;
267
268 memcpy(&fdata.timeout, &compat.timeout,
269 sizeof(struct pps_ktime_compat));
270
271 err = pps_cdev_pps_fetch(pps, fdata: &fdata);
272 if (err)
273 return err;
274
275 /* Return the fetched timestamp */
276 spin_lock_irq(lock: &pps->lock);
277
278 compat.info.assert_sequence = pps->assert_sequence;
279 compat.info.clear_sequence = pps->clear_sequence;
280 compat.info.current_mode = pps->current_mode;
281
282 memcpy(&compat.info.assert_tu, &pps->assert_tu,
283 sizeof(struct pps_ktime_compat));
284 memcpy(&compat.info.clear_tu, &pps->clear_tu,
285 sizeof(struct pps_ktime_compat));
286
287 spin_unlock_irq(lock: &pps->lock);
288
289 return copy_to_user(to: uarg, from: &compat,
290 n: sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
291 }
292
293 return pps_cdev_ioctl(file, cmd, arg);
294}
295#else
296#define pps_cdev_compat_ioctl NULL
297#endif
298
299static struct pps_device *pps_idr_get(unsigned long id)
300{
301 struct pps_device *pps;
302
303 mutex_lock(&pps_idr_lock);
304 pps = idr_find(&pps_idr, id);
305 if (pps)
306 get_device(dev: &pps->dev);
307
308 mutex_unlock(lock: &pps_idr_lock);
309 return pps;
310}
311
312static int pps_cdev_open(struct inode *inode, struct file *file)
313{
314 struct pps_device *pps = pps_idr_get(id: iminor(inode));
315
316 if (!pps)
317 return -ENODEV;
318
319 file->private_data = pps;
320 return 0;
321}
322
323static int pps_cdev_release(struct inode *inode, struct file *file)
324{
325 struct pps_device *pps = file->private_data;
326
327 WARN_ON(pps->id != iminor(inode));
328 put_device(dev: &pps->dev);
329 return 0;
330}
331
332/*
333 * Char device stuff
334 */
335
336static const struct file_operations pps_cdev_fops = {
337 .owner = THIS_MODULE,
338 .poll = pps_cdev_poll,
339 .fasync = pps_cdev_fasync,
340 .compat_ioctl = pps_cdev_compat_ioctl,
341 .unlocked_ioctl = pps_cdev_ioctl,
342 .open = pps_cdev_open,
343 .release = pps_cdev_release,
344};
345
346static void pps_device_destruct(struct device *dev)
347{
348 struct pps_device *pps = dev_get_drvdata(dev);
349
350 pr_debug("deallocating pps%d\n", pps->id);
351 kfree(objp: pps);
352}
353
354int pps_register_cdev(struct pps_device *pps)
355{
356 int err;
357
358 mutex_lock(&pps_idr_lock);
359 /*
360 * Get new ID for the new PPS source. After idr_alloc() calling
361 * the new source will be freely available into the kernel.
362 */
363 err = idr_alloc(&pps_idr, ptr: pps, start: 0, PPS_MAX_SOURCES, GFP_KERNEL);
364 if (err < 0) {
365 if (err == -ENOSPC) {
366 pr_err("%s: too many PPS sources in the system\n",
367 pps->info.name);
368 err = -EBUSY;
369 }
370 goto out_unlock;
371 }
372 pps->id = err;
373
374 pps->dev.class = pps_class;
375 pps->dev.parent = pps->info.dev;
376 pps->dev.devt = MKDEV(pps_major, pps->id);
377 dev_set_drvdata(dev: &pps->dev, data: pps);
378 dev_set_name(dev: &pps->dev, name: "pps%d", pps->id);
379 err = device_register(dev: &pps->dev);
380 if (err)
381 goto free_idr;
382
383 /* Override the release function with our own */
384 pps->dev.release = pps_device_destruct;
385
386 pr_debug("source %s got cdev (%d:%d)\n", pps->info.name, pps_major,
387 pps->id);
388
389 get_device(dev: &pps->dev);
390 mutex_unlock(lock: &pps_idr_lock);
391 return 0;
392
393free_idr:
394 idr_remove(&pps_idr, id: pps->id);
395 put_device(dev: &pps->dev);
396out_unlock:
397 mutex_unlock(lock: &pps_idr_lock);
398 return err;
399}
400
401void pps_unregister_cdev(struct pps_device *pps)
402{
403 pr_debug("unregistering pps%d\n", pps->id);
404 pps->lookup_cookie = NULL;
405 device_destroy(cls: pps_class, devt: pps->dev.devt);
406
407 /* Now we can release the ID for re-use */
408 mutex_lock(&pps_idr_lock);
409 idr_remove(&pps_idr, id: pps->id);
410 put_device(dev: &pps->dev);
411 mutex_unlock(lock: &pps_idr_lock);
412}
413
414/*
415 * Look up a pps device by magic cookie.
416 * The cookie is usually a pointer to some enclosing device, but this
417 * code doesn't care; you should never be dereferencing it.
418 *
419 * This is a bit of a kludge that is currently used only by the PPS
420 * serial line discipline. It may need to be tweaked when a second user
421 * is found.
422 *
423 * There is no function interface for setting the lookup_cookie field.
424 * It's initialized to NULL when the pps device is created, and if a
425 * client wants to use it, just fill it in afterward.
426 *
427 * The cookie is automatically set to NULL in pps_unregister_source()
428 * so that it will not be used again, even if the pps device cannot
429 * be removed from the idr due to pending references holding the minor
430 * number in use.
431 *
432 * Since pps_idr holds a reference to the device, the returned
433 * pps_device is guaranteed to be valid until pps_unregister_cdev() is
434 * called on it. But after calling pps_unregister_cdev(), it may be
435 * freed at any time.
436 */
437struct pps_device *pps_lookup_dev(void const *cookie)
438{
439 struct pps_device *pps;
440 unsigned id;
441
442 rcu_read_lock();
443 idr_for_each_entry(&pps_idr, pps, id)
444 if (cookie == pps->lookup_cookie)
445 break;
446 rcu_read_unlock();
447 return pps;
448}
449EXPORT_SYMBOL(pps_lookup_dev);
450
451/*
452 * Module stuff
453 */
454
455static void __exit pps_exit(void)
456{
457 class_destroy(cls: pps_class);
458 __unregister_chrdev(major: pps_major, baseminor: 0, PPS_MAX_SOURCES, name: "pps");
459}
460
461static int __init pps_init(void)
462{
463 pps_class = class_create(name: "pps");
464 if (IS_ERR(ptr: pps_class)) {
465 pr_err("failed to allocate class\n");
466 return PTR_ERR(ptr: pps_class);
467 }
468 pps_class->dev_groups = pps_groups;
469
470 pps_major = __register_chrdev(major: 0, baseminor: 0, PPS_MAX_SOURCES, name: "pps",
471 fops: &pps_cdev_fops);
472 if (pps_major < 0) {
473 pr_err("failed to allocate char device region\n");
474 goto remove_class;
475 }
476
477 pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
478 pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
479 "<giometti@linux.it>\n", PPS_VERSION);
480
481 return 0;
482
483remove_class:
484 class_destroy(cls: pps_class);
485 return pps_major;
486}
487
488subsys_initcall(pps_init);
489module_exit(pps_exit);
490
491MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
492MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
493MODULE_LICENSE("GPL");
494

source code of linux/drivers/pps/pps.c