aboutsummaryrefslogtreecommitdiff
path: root/drivers/pps/kapi.c
blob: 3f89f5eba81c80b0b9d96cd37745c75be993fc29 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
/*
 * kernel API
 *
 *
 * Copyright (C) 2005-2009   Rodolfo Giometti <giometti@linux.it>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/spinlock.h>
#include <linux/idr.h>
#include <linux/fs.h>
#include <linux/pps_kernel.h>
#include <linux/slab.h>

/*
 * Global variables
 */

DEFINE_SPINLOCK(pps_idr_lock);
DEFINE_IDR(pps_idr);

/*
 * Local functions
 */

static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
{
	ts->nsec += offset->nsec;
	while (ts->nsec >= NSEC_PER_SEC) {
		ts->nsec -= NSEC_PER_SEC;
		ts->sec++;
	}
	while (ts->nsec < 0) {
		ts->nsec += NSEC_PER_SEC;
		ts->sec--;
	}
	ts->sec += offset->sec;
}

/*
 * Exported functions
 */

/* pps_get_source - find a PPS source
 * @source: the PPS source ID.
 *
 * This function is used to find an already registered PPS source into the
 * system.
 *
 * The function returns NULL if found nothing, otherwise it returns a pointer
 * to the PPS source data struct (the refcounter is incremented by 1).
 */

struct pps_device *pps_get_source(int source)
{
	struct pps_device *pps;
	unsigned long flags;

	spin_lock_irqsave(&pps_idr_lock, flags);

	pps = idr_find(&pps_idr, source);
	if (pps != NULL)
		atomic_inc(&pps->usage);

	spin_unlock_irqrestore(&pps_idr_lock, flags);

	return pps;
}

/* pps_put_source - free the PPS source data
 * @pps: a pointer to the PPS source.
 *
 * This function is used to free a PPS data struct if its refcount is 0.
 */

void pps_put_source(struct pps_device *pps)
{
	unsigned long flags;

	spin_lock_irqsave(&pps_idr_lock, flags);
	BUG_ON(atomic_read(&pps->usage) == 0);

	if (!atomic_dec_and_test(&pps->usage)) {
		pps = NULL;
		goto exit;
	}

	/* No more reference to the PPS source. We can safely remove the
	 * PPS data struct.
	 */
	idr_remove(&pps_idr, pps->id);

exit:
	spin_unlock_irqrestore(&pps_idr_lock, flags);
	kfree(pps);
}

/* pps_register_source - add a PPS source in the system
 * @info: the PPS info struct
 * @default_params: the default PPS parameters of the new source
 *
 * This function is used to add a new PPS source in the system. The new
 * source is described by info's fields and it will have, as default PPS
 * parameters, the ones specified into default_params.
 *
 * The function returns, in case of success, the PPS source ID.
 */

int pps_register_source(struct pps_source_info *info, int default_params)
{
	struct pps_device *pps;
	int id;
	int err;

	/* Sanity checks */
	if ((info->mode & default_params) != default_params) {
		printk(KERN_ERR "pps: %s: unsupported default parameters\n",
					info->name);
		err = -EINVAL;
		goto pps_register_source_exit;
	}
	if ((info->mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) != 0 &&
			info->echo == NULL) {
		printk(KERN_ERR "pps: %s: echo function is not defined\n",
					info->name);
		err = -EINVAL;
		goto pps_register_source_exit;
	}
	if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
		printk(KERN_ERR "pps: %s: unspecified time format\n",
					info->name);
		err = -EINVAL;
		goto pps_register_source_exit;
	}

	/* Allocate memory for the new PPS source struct */
	pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
	if (pps == NULL) {
		err = -ENOMEM;
		goto pps_register_source_exit;
	}

	/* These initializations must be done before calling idr_get_new()
	 * in order to avoid reces into pps_event().
	 */
	pps->params.api_version = PPS_API_VERS;
	pps->params.mode = default_params;
	pps->info = *info;

	init_waitqueue_head(&pps->queue);
	spin_lock_init(&pps->lock);
	atomic_set(&pps->usage, 1);

	/* Get new ID for the new PPS source */
	if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
		err = -ENOMEM;
		goto kfree_pps;
	}

	spin_lock_irq(&pps_idr_lock);

	/* Now really allocate the PPS source.
	 * After idr_get_new() calling the new source will be freely available
	 * into the kernel.
	 */
	err = idr_get_new(&pps_idr, pps, &id);
	if (err < 0) {
		spin_unlock_irq(&pps_idr_lock);
		goto kfree_pps;
	}

	id = id & MAX_ID_MASK;
	if (id >= PPS_MAX_SOURCES) {
		spin_unlock_irq(&pps_idr_lock);

		printk(KERN_ERR "pps: %s: too many PPS sources in the system\n",
					info->name);
		err = -EBUSY;
		goto free_idr;
	}
	pps->id = id;

	spin_unlock_irq(&pps_idr_lock);

	/* Create the char device */
	err = pps_register_cdev(pps);
	if (err < 0) {
		printk(KERN_ERR "pps: %s: unable to create char device\n",
					info->name);
		goto free_idr;
	}

	pr_info("new PPS source %s at ID %d\n", info->name, id);

	return id;

free_idr:
	spin_lock_irq(&pps_idr_lock);
	idr_remove(&pps_idr, id);
	spin_unlock_irq(&pps_idr_lock);

kfree_pps:
	kfree(pps);

pps_register_source_exit:
	printk(KERN_ERR "pps: %s: unable to register source\n", info->name);

	return err;
}
EXPORT_SYMBOL(pps_register_source);

/* pps_unregister_source - remove a PPS source from the system
 * @source: the PPS source ID
 *
 * This function is used to remove a previously registered PPS source from
 * the system.
 */

void pps_unregister_source(int source)
{
	struct pps_device *pps;

	spin_lock_irq(&pps_idr_lock);
	pps = idr_find(&pps_idr, source);

	if (!pps) {
		BUG();
		spin_unlock_irq(&pps_idr_lock);
		return;
	}
	spin_unlock_irq(&pps_idr_lock);

	pps_unregister_cdev(pps);
	pps_put_source(pps);
}
EXPORT_SYMBOL(pps_unregister_source);

/* pps_event - register a PPS event into the system
 * @source: the PPS source ID
 * @ts: the event timestamp
 * @event: the event type
 * @data: userdef pointer
 *
 * This function is used by each PPS client in order to register a new
 * PPS event into the system (it's usually called inside an IRQ handler).
 *
 * If an echo function is associated with the PPS source it will be called
 * as:
 *	pps->info.echo(source, event, data);
 */

void pps_event(int source, struct pps_ktime *ts, int event, void *data)
{
	struct pps_device *pps;
	unsigned long flags;
	int captured = 0;

	if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) {
		printk(KERN_ERR "pps: unknown event (%x) for source %d\n",
			event, source);
		return;
	}

	pps = pps_get_source(source);
	if (!pps)
		return;

	pr_debug("PPS event on source %d at %llu.%06u\n",
			pps->id, (unsigned long long) ts->sec, ts->nsec);

	spin_lock_irqsave(&pps->lock, flags);

	/* Must call the echo function? */
	if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
		pps->info.echo(source, event, data);

	/* Check the event */
	pps->current_mode = pps->params.mode;
	if ((event & PPS_CAPTUREASSERT) &
			(pps->params.mode & PPS_CAPTUREASSERT)) {
		/* We have to add an offset? */
		if (pps->params.mode & PPS_OFFSETASSERT)
			pps_add_offset(ts, &pps->params.assert_off_tu);

		/* Save the time stamp */
		pps->assert_tu = *ts;
		pps->assert_sequence++;
		pr_debug("capture assert seq #%u for source %d\n",
			pps->assert_sequence, source);

		captured = ~0;
	}
	if ((event & PPS_CAPTURECLEAR) &
			(pps->params.mode & PPS_CAPTURECLEAR)) {
		/* We have to add an offset? */
		if (pps->params.mode & PPS_OFFSETCLEAR)
			pps_add_offset(ts, &pps->params.clear_off_tu);

		/* Save the time stamp */
		pps->clear_tu = *ts;
		pps->clear_sequence++;
		pr_debug("capture clear seq #%u for source %d\n",
			pps->clear_sequence, source);

		captured = ~0;
	}

	/* Wake up if captured something */
	if (captured) {
		pps->last_ev++;
		wake_up_interruptible_all(&pps->queue);

		kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
	}

	spin_unlock_irqrestore(&pps->lock, flags);

	/* Now we can release the PPS source for (possible) deregistration */
	pps_put_source(pps);
}
EXPORT_SYMBOL(pps_event);