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#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/time.h>
29#include <linux/timex.h>
30#include <linux/spinlock.h>
31#include <linux/fs.h>
32#include <linux/pps_kernel.h>
33#include <linux/slab.h>
34
35#include "kc.h"
36
37/*
38 * Local functions
39 */
40
41static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
42{
43	ts->nsec += offset->nsec;
44	while (ts->nsec >= NSEC_PER_SEC) {
45		ts->nsec -= NSEC_PER_SEC;
46		ts->sec++;
47	}
48	while (ts->nsec < 0) {
49		ts->nsec += NSEC_PER_SEC;
50		ts->sec--;
51	}
52	ts->sec += offset->sec;
53}
54
55static void pps_echo_client_default(struct pps_device *pps, int event,
56		void *data)
57{
58	dev_info(pps->dev, "echo %s %s\n",
59		event & PPS_CAPTUREASSERT ? "assert" : "",
60		event & PPS_CAPTURECLEAR ? "clear" : "");
61}
62
63/*
64 * Exported functions
65 */
66
67/* pps_register_source - add a PPS source in the system
68 * @info: the PPS info struct
69 * @default_params: the default PPS parameters of the new source
70 *
71 * This function is used to add a new PPS source in the system. The new
72 * source is described by info's fields and it will have, as default PPS
73 * parameters, the ones specified into default_params.
74 *
75 * The function returns, in case of success, the PPS device. Otherwise NULL.
76 */
77
78struct pps_device *pps_register_source(struct pps_source_info *info,
79		int default_params)
80{
81	struct pps_device *pps;
82	int err;
83
84	/* Sanity checks */
85	if ((info->mode & default_params) != default_params) {
86		pr_err("%s: unsupported default parameters\n",
87					info->name);
88		err = -EINVAL;
89		goto pps_register_source_exit;
90	}
91	if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
92		pr_err("%s: unspecified time format\n",
93					info->name);
94		err = -EINVAL;
95		goto pps_register_source_exit;
96	}
97
98	/* Allocate memory for the new PPS source struct */
99	pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
100	if (pps == NULL) {
101		err = -ENOMEM;
102		goto pps_register_source_exit;
103	}
104
105	/* These initializations must be done before calling idr_alloc()
106	 * in order to avoid reces into pps_event().
107	 */
108	pps->params.api_version = PPS_API_VERS;
109	pps->params.mode = default_params;
110	pps->info = *info;
111
112	/* check for default echo function */
113	if ((pps->info.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) &&
114			pps->info.echo == NULL)
115		pps->info.echo = pps_echo_client_default;
116
117	init_waitqueue_head(&pps->queue);
118	spin_lock_init(&pps->lock);
119
120	/* Create the char device */
121	err = pps_register_cdev(pps);
122	if (err < 0) {
123		pr_err("%s: unable to create char device\n",
124					info->name);
125		goto kfree_pps;
126	}
127
128	dev_info(pps->dev, "new PPS source %s\n", info->name);
129
130	return pps;
131
132kfree_pps:
133	kfree(pps);
134
135pps_register_source_exit:
136	pr_err("%s: unable to register source\n", info->name);
137
138	return NULL;
139}
140EXPORT_SYMBOL(pps_register_source);
141
142/* pps_unregister_source - remove a PPS source from the system
143 * @pps: the PPS source
144 *
145 * This function is used to remove a previously registered PPS source from
146 * the system.
147 */
148
149void pps_unregister_source(struct pps_device *pps)
150{
151	pps_kc_remove(pps);
152	pps_unregister_cdev(pps);
153
154	/* don't have to kfree(pps) here because it will be done on
155	 * device destruction */
156}
157EXPORT_SYMBOL(pps_unregister_source);
158
159/* pps_event - register a PPS event into the system
160 * @pps: the PPS device
161 * @ts: the event timestamp
162 * @event: the event type
163 * @data: userdef pointer
164 *
165 * This function is used by each PPS client in order to register a new
166 * PPS event into the system (it's usually called inside an IRQ handler).
167 *
168 * If an echo function is associated with the PPS device it will be called
169 * as:
170 *	pps->info.echo(pps, event, data);
171 */
172void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
173		void *data)
174{
175	unsigned long flags;
176	int captured = 0;
177	struct pps_ktime ts_real = { .sec = 0, .nsec = 0, .flags = 0 };
178
179	/* check event type */
180	BUG_ON((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0);
181
182	dev_dbg(pps->dev, "PPS event at %ld.%09ld\n",
183			ts->ts_real.tv_sec, ts->ts_real.tv_nsec);
184
185	timespec_to_pps_ktime(&ts_real, ts->ts_real);
186
187	spin_lock_irqsave(&pps->lock, flags);
188
189	/* Must call the echo function? */
190	if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
191		pps->info.echo(pps, event, data);
192
193	/* Check the event */
194	pps->current_mode = pps->params.mode;
195	if (event & pps->params.mode & PPS_CAPTUREASSERT) {
196		/* We have to add an offset? */
197		if (pps->params.mode & PPS_OFFSETASSERT)
198			pps_add_offset(&ts_real,
199					&pps->params.assert_off_tu);
200
201		/* Save the time stamp */
202		pps->assert_tu = ts_real;
203		pps->assert_sequence++;
204		dev_dbg(pps->dev, "capture assert seq #%u\n",
205			pps->assert_sequence);
206
207		captured = ~0;
208	}
209	if (event & pps->params.mode & PPS_CAPTURECLEAR) {
210		/* We have to add an offset? */
211		if (pps->params.mode & PPS_OFFSETCLEAR)
212			pps_add_offset(&ts_real,
213					&pps->params.clear_off_tu);
214
215		/* Save the time stamp */
216		pps->clear_tu = ts_real;
217		pps->clear_sequence++;
218		dev_dbg(pps->dev, "capture clear seq #%u\n",
219			pps->clear_sequence);
220
221		captured = ~0;
222	}
223
224	pps_kc_event(pps, ts, event);
225
226	/* Wake up if captured something */
227	if (captured) {
228		pps->last_ev++;
229		wake_up_interruptible_all(&pps->queue);
230
231		kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
232	}
233
234	spin_unlock_irqrestore(&pps->lock, flags);
235}
236EXPORT_SYMBOL(pps_event);
237