LinuxPPS: core support
[linux-2.6.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
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/sched.h>
27 #include <linux/uaccess.h>
28 #include <linux/idr.h>
29 #include <linux/cdev.h>
30 #include <linux/poll.h>
31 #include <linux/pps_kernel.h>
32
33 /*
34  * Local variables
35  */
36
37 static dev_t pps_devt;
38 static struct class *pps_class;
39
40 /*
41  * Char device methods
42  */
43
44 static unsigned int pps_cdev_poll(struct file *file, poll_table *wait)
45 {
46         struct pps_device *pps = file->private_data;
47
48         poll_wait(file, &pps->queue, wait);
49
50         return POLLIN | POLLRDNORM;
51 }
52
53 static int pps_cdev_fasync(int fd, struct file *file, int on)
54 {
55         struct pps_device *pps = file->private_data;
56         return fasync_helper(fd, file, on, &pps->async_queue);
57 }
58
59 static long pps_cdev_ioctl(struct file *file,
60                 unsigned int cmd, unsigned long arg)
61 {
62         struct pps_device *pps = file->private_data;
63         struct pps_kparams params;
64         struct pps_fdata fdata;
65         unsigned long ticks;
66         void __user *uarg = (void __user *) arg;
67         int __user *iuarg = (int __user *) arg;
68         int err;
69
70         switch (cmd) {
71         case PPS_GETPARAMS:
72                 pr_debug("PPS_GETPARAMS: source %d\n", pps->id);
73
74                 /* Return current parameters */
75                 err = copy_to_user(uarg, &pps->params,
76                                                 sizeof(struct pps_kparams));
77                 if (err)
78                         return -EFAULT;
79
80                 break;
81
82         case PPS_SETPARAMS:
83                 pr_debug("PPS_SETPARAMS: source %d\n", pps->id);
84
85                 /* Check the capabilities */
86                 if (!capable(CAP_SYS_TIME))
87                         return -EPERM;
88
89                 err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
90                 if (err)
91                         return -EFAULT;
92                 if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {
93                         pr_debug("capture mode unspecified (%x)\n",
94                                                                 params.mode);
95                         return -EINVAL;
96                 }
97
98                 /* Check for supported capabilities */
99                 if ((params.mode & ~pps->info.mode) != 0) {
100                         pr_debug("unsupported capabilities (%x)\n",
101                                                                 params.mode);
102                         return -EINVAL;
103                 }
104
105                 spin_lock_irq(&pps->lock);
106
107                 /* Save the new parameters */
108                 pps->params = params;
109
110                 /* Restore the read only parameters */
111                 if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
112                         /* section 3.3 of RFC 2783 interpreted */
113                         pr_debug("time format unspecified (%x)\n",
114                                                                 params.mode);
115                         pps->params.mode |= PPS_TSFMT_TSPEC;
116                 }
117                 if (pps->info.mode & PPS_CANWAIT)
118                         pps->params.mode |= PPS_CANWAIT;
119                 pps->params.api_version = PPS_API_VERS;
120
121                 spin_unlock_irq(&pps->lock);
122
123                 break;
124
125         case PPS_GETCAP:
126                 pr_debug("PPS_GETCAP: source %d\n", pps->id);
127
128                 err = put_user(pps->info.mode, iuarg);
129                 if (err)
130                         return -EFAULT;
131
132                 break;
133
134         case PPS_FETCH:
135                 pr_debug("PPS_FETCH: source %d\n", pps->id);
136
137                 err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
138                 if (err)
139                         return -EFAULT;
140
141                 pps->go = 0;
142
143                 /* Manage the timeout */
144                 if (fdata.timeout.flags & PPS_TIME_INVALID)
145                         err = wait_event_interruptible(pps->queue, pps->go);
146                 else {
147                         pr_debug("timeout %lld.%09d\n",
148                                         (long long) fdata.timeout.sec,
149                                         fdata.timeout.nsec);
150                         ticks = fdata.timeout.sec * HZ;
151                         ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
152
153                         if (ticks != 0) {
154                                 err = wait_event_interruptible_timeout(
155                                                 pps->queue, pps->go, ticks);
156                                 if (err == 0)
157                                         return -ETIMEDOUT;
158                         }
159                 }
160
161                 /* Check for pending signals */
162                 if (err == -ERESTARTSYS) {
163                         pr_debug("pending signal caught\n");
164                         return -EINTR;
165                 }
166
167                 /* Return the fetched timestamp */
168                 spin_lock_irq(&pps->lock);
169
170                 fdata.info.assert_sequence = pps->assert_sequence;
171                 fdata.info.clear_sequence = pps->clear_sequence;
172                 fdata.info.assert_tu = pps->assert_tu;
173                 fdata.info.clear_tu = pps->clear_tu;
174                 fdata.info.current_mode = pps->current_mode;
175
176                 spin_unlock_irq(&pps->lock);
177
178                 err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
179                 if (err)
180                         return -EFAULT;
181
182                 break;
183
184         default:
185                 return -ENOTTY;
186                 break;
187         }
188
189         return 0;
190 }
191
192 static int pps_cdev_open(struct inode *inode, struct file *file)
193 {
194         struct pps_device *pps = container_of(inode->i_cdev,
195                                                 struct pps_device, cdev);
196         int found;
197
198         found = pps_get_source(pps->id) != 0;
199         if (!found)
200                 return -ENODEV;
201
202         file->private_data = pps;
203
204         return 0;
205 }
206
207 static int pps_cdev_release(struct inode *inode, struct file *file)
208 {
209         struct pps_device *pps = file->private_data;
210
211         /* Free the PPS source and wake up (possible) deregistration */
212         pps_put_source(pps);
213
214         return 0;
215 }
216
217 /*
218  * Char device stuff
219  */
220
221 static const struct file_operations pps_cdev_fops = {
222         .owner          = THIS_MODULE,
223         .llseek         = no_llseek,
224         .poll           = pps_cdev_poll,
225         .fasync         = pps_cdev_fasync,
226         .unlocked_ioctl = pps_cdev_ioctl,
227         .open           = pps_cdev_open,
228         .release        = pps_cdev_release,
229 };
230
231 int pps_register_cdev(struct pps_device *pps)
232 {
233         int err;
234
235         pps->devno = MKDEV(MAJOR(pps_devt), pps->id);
236         cdev_init(&pps->cdev, &pps_cdev_fops);
237         pps->cdev.owner = pps->info.owner;
238
239         err = cdev_add(&pps->cdev, pps->devno, 1);
240         if (err) {
241                 printk(KERN_ERR "pps: %s: failed to add char device %d:%d\n",
242                                 pps->info.name, MAJOR(pps_devt), pps->id);
243                 return err;
244         }
245         pps->dev = device_create(pps_class, pps->info.dev, pps->devno, NULL,
246                                                         "pps%d", pps->id);
247         if (err)
248                 goto del_cdev;
249         dev_set_drvdata(pps->dev, pps);
250
251         pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
252                         MAJOR(pps_devt), pps->id);
253
254         return 0;
255
256 del_cdev:
257         cdev_del(&pps->cdev);
258
259         return err;
260 }
261
262 void pps_unregister_cdev(struct pps_device *pps)
263 {
264         device_destroy(pps_class, pps->devno);
265         cdev_del(&pps->cdev);
266 }
267
268 /*
269  * Module stuff
270  */
271
272 static void __exit pps_exit(void)
273 {
274         class_destroy(pps_class);
275         unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
276 }
277
278 static int __init pps_init(void)
279 {
280         int err;
281
282         pps_class = class_create(THIS_MODULE, "pps");
283         if (!pps_class) {
284                 printk(KERN_ERR "pps: failed to allocate class\n");
285                 return -ENOMEM;
286         }
287         pps_class->dev_attrs = pps_attrs;
288
289         err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
290         if (err < 0) {
291                 printk(KERN_ERR "pps: failed to allocate char device region\n");
292                 goto remove_class;
293         }
294
295         pr_info("LinuxPPS API ver. %d registered\n", PPS_API_VERS);
296         pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
297                 "<giometti@linux.it>\n", PPS_VERSION);
298
299         return 0;
300
301 remove_class:
302         class_destroy(pps_class);
303
304         return err;
305 }
306
307 subsys_initcall(pps_init);
308 module_exit(pps_exit);
309
310 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
311 MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
312 MODULE_LICENSE("GPL");