Root/drivers/pps/kapi.c

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_get_new()
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

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