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eae9d2ba RG |
1 | /* |
2 | * kernel API | |
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/time.h> | |
28 | #include <linux/spinlock.h> | |
29 | #include <linux/idr.h> | |
30 | #include <linux/fs.h> | |
31 | #include <linux/pps_kernel.h> | |
5a0e3ad6 | 32 | #include <linux/slab.h> |
eae9d2ba RG |
33 | |
34 | /* | |
35 | * Global variables | |
36 | */ | |
37 | ||
38 | DEFINE_SPINLOCK(pps_idr_lock); | |
39 | DEFINE_IDR(pps_idr); | |
40 | ||
41 | /* | |
42 | * Local functions | |
43 | */ | |
44 | ||
45 | static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset) | |
46 | { | |
47 | ts->nsec += offset->nsec; | |
48 | while (ts->nsec >= NSEC_PER_SEC) { | |
49 | ts->nsec -= NSEC_PER_SEC; | |
50 | ts->sec++; | |
51 | } | |
52 | while (ts->nsec < 0) { | |
53 | ts->nsec += NSEC_PER_SEC; | |
54 | ts->sec--; | |
55 | } | |
56 | ts->sec += offset->sec; | |
57 | } | |
58 | ||
59 | /* | |
60 | * Exported functions | |
61 | */ | |
62 | ||
63 | /* pps_get_source - find a PPS source | |
64 | * @source: the PPS source ID. | |
65 | * | |
66 | * This function is used to find an already registered PPS source into the | |
67 | * system. | |
68 | * | |
69 | * The function returns NULL if found nothing, otherwise it returns a pointer | |
70 | * to the PPS source data struct (the refcounter is incremented by 1). | |
71 | */ | |
72 | ||
73 | struct pps_device *pps_get_source(int source) | |
74 | { | |
75 | struct pps_device *pps; | |
76 | unsigned long flags; | |
77 | ||
78 | spin_lock_irqsave(&pps_idr_lock, flags); | |
79 | ||
80 | pps = idr_find(&pps_idr, source); | |
81 | if (pps != NULL) | |
82 | atomic_inc(&pps->usage); | |
83 | ||
84 | spin_unlock_irqrestore(&pps_idr_lock, flags); | |
85 | ||
86 | return pps; | |
87 | } | |
88 | ||
89 | /* pps_put_source - free the PPS source data | |
90 | * @pps: a pointer to the PPS source. | |
91 | * | |
92 | * This function is used to free a PPS data struct if its refcount is 0. | |
93 | */ | |
94 | ||
95 | void pps_put_source(struct pps_device *pps) | |
96 | { | |
97 | unsigned long flags; | |
98 | ||
99 | spin_lock_irqsave(&pps_idr_lock, flags); | |
100 | BUG_ON(atomic_read(&pps->usage) == 0); | |
101 | ||
102 | if (!atomic_dec_and_test(&pps->usage)) { | |
103 | pps = NULL; | |
104 | goto exit; | |
105 | } | |
106 | ||
107 | /* No more reference to the PPS source. We can safely remove the | |
108 | * PPS data struct. | |
109 | */ | |
110 | idr_remove(&pps_idr, pps->id); | |
111 | ||
112 | exit: | |
113 | spin_unlock_irqrestore(&pps_idr_lock, flags); | |
114 | kfree(pps); | |
115 | } | |
116 | ||
117 | /* pps_register_source - add a PPS source in the system | |
118 | * @info: the PPS info struct | |
119 | * @default_params: the default PPS parameters of the new source | |
120 | * | |
121 | * This function is used to add a new PPS source in the system. The new | |
122 | * source is described by info's fields and it will have, as default PPS | |
123 | * parameters, the ones specified into default_params. | |
124 | * | |
125 | * The function returns, in case of success, the PPS source ID. | |
126 | */ | |
127 | ||
128 | int pps_register_source(struct pps_source_info *info, int default_params) | |
129 | { | |
130 | struct pps_device *pps; | |
131 | int id; | |
132 | int err; | |
133 | ||
134 | /* Sanity checks */ | |
135 | if ((info->mode & default_params) != default_params) { | |
136 | printk(KERN_ERR "pps: %s: unsupported default parameters\n", | |
137 | info->name); | |
138 | err = -EINVAL; | |
139 | goto pps_register_source_exit; | |
140 | } | |
141 | if ((info->mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) != 0 && | |
142 | info->echo == NULL) { | |
143 | printk(KERN_ERR "pps: %s: echo function is not defined\n", | |
144 | info->name); | |
145 | err = -EINVAL; | |
146 | goto pps_register_source_exit; | |
147 | } | |
148 | if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) { | |
149 | printk(KERN_ERR "pps: %s: unspecified time format\n", | |
150 | info->name); | |
151 | err = -EINVAL; | |
152 | goto pps_register_source_exit; | |
153 | } | |
154 | ||
155 | /* Allocate memory for the new PPS source struct */ | |
156 | pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL); | |
157 | if (pps == NULL) { | |
158 | err = -ENOMEM; | |
159 | goto pps_register_source_exit; | |
160 | } | |
161 | ||
162 | /* These initializations must be done before calling idr_get_new() | |
163 | * in order to avoid reces into pps_event(). | |
164 | */ | |
165 | pps->params.api_version = PPS_API_VERS; | |
166 | pps->params.mode = default_params; | |
167 | pps->info = *info; | |
168 | ||
169 | init_waitqueue_head(&pps->queue); | |
170 | spin_lock_init(&pps->lock); | |
171 | atomic_set(&pps->usage, 1); | |
172 | ||
173 | /* Get new ID for the new PPS source */ | |
174 | if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) { | |
175 | err = -ENOMEM; | |
176 | goto kfree_pps; | |
177 | } | |
178 | ||
179 | spin_lock_irq(&pps_idr_lock); | |
180 | ||
181 | /* Now really allocate the PPS source. | |
182 | * After idr_get_new() calling the new source will be freely available | |
183 | * into the kernel. | |
184 | */ | |
185 | err = idr_get_new(&pps_idr, pps, &id); | |
186 | if (err < 0) { | |
187 | spin_unlock_irq(&pps_idr_lock); | |
188 | goto kfree_pps; | |
189 | } | |
190 | ||
191 | id = id & MAX_ID_MASK; | |
192 | if (id >= PPS_MAX_SOURCES) { | |
193 | spin_unlock_irq(&pps_idr_lock); | |
194 | ||
195 | printk(KERN_ERR "pps: %s: too many PPS sources in the system\n", | |
196 | info->name); | |
197 | err = -EBUSY; | |
198 | goto free_idr; | |
199 | } | |
200 | pps->id = id; | |
201 | ||
202 | spin_unlock_irq(&pps_idr_lock); | |
203 | ||
204 | /* Create the char device */ | |
205 | err = pps_register_cdev(pps); | |
206 | if (err < 0) { | |
207 | printk(KERN_ERR "pps: %s: unable to create char device\n", | |
208 | info->name); | |
209 | goto free_idr; | |
210 | } | |
211 | ||
212 | pr_info("new PPS source %s at ID %d\n", info->name, id); | |
213 | ||
214 | return id; | |
215 | ||
216 | free_idr: | |
217 | spin_lock_irq(&pps_idr_lock); | |
218 | idr_remove(&pps_idr, id); | |
219 | spin_unlock_irq(&pps_idr_lock); | |
220 | ||
221 | kfree_pps: | |
222 | kfree(pps); | |
223 | ||
224 | pps_register_source_exit: | |
225 | printk(KERN_ERR "pps: %s: unable to register source\n", info->name); | |
226 | ||
227 | return err; | |
228 | } | |
229 | EXPORT_SYMBOL(pps_register_source); | |
230 | ||
231 | /* pps_unregister_source - remove a PPS source from the system | |
232 | * @source: the PPS source ID | |
233 | * | |
234 | * This function is used to remove a previously registered PPS source from | |
235 | * the system. | |
236 | */ | |
237 | ||
238 | void pps_unregister_source(int source) | |
239 | { | |
240 | struct pps_device *pps; | |
241 | ||
242 | spin_lock_irq(&pps_idr_lock); | |
243 | pps = idr_find(&pps_idr, source); | |
244 | ||
245 | if (!pps) { | |
246 | BUG(); | |
247 | spin_unlock_irq(&pps_idr_lock); | |
248 | return; | |
249 | } | |
250 | spin_unlock_irq(&pps_idr_lock); | |
251 | ||
252 | pps_unregister_cdev(pps); | |
253 | pps_put_source(pps); | |
254 | } | |
255 | EXPORT_SYMBOL(pps_unregister_source); | |
256 | ||
257 | /* pps_event - register a PPS event into the system | |
258 | * @source: the PPS source ID | |
259 | * @ts: the event timestamp | |
260 | * @event: the event type | |
261 | * @data: userdef pointer | |
262 | * | |
263 | * This function is used by each PPS client in order to register a new | |
264 | * PPS event into the system (it's usually called inside an IRQ handler). | |
265 | * | |
266 | * If an echo function is associated with the PPS source it will be called | |
267 | * as: | |
268 | * pps->info.echo(source, event, data); | |
269 | */ | |
270 | ||
271 | void pps_event(int source, struct pps_ktime *ts, int event, void *data) | |
272 | { | |
273 | struct pps_device *pps; | |
274 | unsigned long flags; | |
276b282e | 275 | int captured = 0; |
eae9d2ba RG |
276 | |
277 | if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) { | |
278 | printk(KERN_ERR "pps: unknown event (%x) for source %d\n", | |
279 | event, source); | |
280 | return; | |
281 | } | |
282 | ||
283 | pps = pps_get_source(source); | |
284 | if (!pps) | |
285 | return; | |
286 | ||
287 | pr_debug("PPS event on source %d at %llu.%06u\n", | |
288 | pps->id, (unsigned long long) ts->sec, ts->nsec); | |
289 | ||
290 | spin_lock_irqsave(&pps->lock, flags); | |
291 | ||
292 | /* Must call the echo function? */ | |
293 | if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR))) | |
294 | pps->info.echo(source, event, data); | |
295 | ||
296 | /* Check the event */ | |
297 | pps->current_mode = pps->params.mode; | |
276b282e RG |
298 | if ((event & PPS_CAPTUREASSERT) & |
299 | (pps->params.mode & PPS_CAPTUREASSERT)) { | |
eae9d2ba RG |
300 | /* We have to add an offset? */ |
301 | if (pps->params.mode & PPS_OFFSETASSERT) | |
302 | pps_add_offset(ts, &pps->params.assert_off_tu); | |
303 | ||
304 | /* Save the time stamp */ | |
305 | pps->assert_tu = *ts; | |
306 | pps->assert_sequence++; | |
307 | pr_debug("capture assert seq #%u for source %d\n", | |
308 | pps->assert_sequence, source); | |
276b282e RG |
309 | |
310 | captured = ~0; | |
eae9d2ba | 311 | } |
276b282e RG |
312 | if ((event & PPS_CAPTURECLEAR) & |
313 | (pps->params.mode & PPS_CAPTURECLEAR)) { | |
eae9d2ba RG |
314 | /* We have to add an offset? */ |
315 | if (pps->params.mode & PPS_OFFSETCLEAR) | |
316 | pps_add_offset(ts, &pps->params.clear_off_tu); | |
317 | ||
318 | /* Save the time stamp */ | |
319 | pps->clear_tu = *ts; | |
320 | pps->clear_sequence++; | |
321 | pr_debug("capture clear seq #%u for source %d\n", | |
322 | pps->clear_sequence, source); | |
276b282e RG |
323 | |
324 | captured = ~0; | |
eae9d2ba RG |
325 | } |
326 | ||
276b282e RG |
327 | /* Wake up iif captured somthing */ |
328 | if (captured) { | |
329 | pps->go = ~0; | |
330 | wake_up_interruptible(&pps->queue); | |
eae9d2ba | 331 | |
276b282e RG |
332 | kill_fasync(&pps->async_queue, SIGIO, POLL_IN); |
333 | } | |
eae9d2ba RG |
334 | |
335 | spin_unlock_irqrestore(&pps->lock, flags); | |
336 | ||
337 | /* Now we can release the PPS source for (possible) deregistration */ | |
338 | pps_put_source(pps); | |
339 | } | |
340 | EXPORT_SYMBOL(pps_event); |