Merge branches 'iommu/fixes', 'x86/vt-d', 'x86/amd', 'ppc/pamu', 'core' and 'arm...
[firefly-linux-kernel-4.4.55.git] / drivers / pps / pps.c
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_attrs = pps_attrs;
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");