Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target...
[linux-btrfs-devel.git] / drivers / pps / kapi.c
bloba4e8eb9fece6a53c7e2ade169df43dcd9a8696a0
1 /*
2 * kernel API
5 * Copyright (C) 2005-2009 Rodolfo Giometti <giometti@linux.it>
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.
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.
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.
22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
35 #include "kc.h"
38 * Local functions
41 static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
43 ts->nsec += offset->nsec;
44 while (ts->nsec >= NSEC_PER_SEC) {
45 ts->nsec -= NSEC_PER_SEC;
46 ts->sec++;
48 while (ts->nsec < 0) {
49 ts->nsec += NSEC_PER_SEC;
50 ts->sec--;
52 ts->sec += offset->sec;
56 * Exported functions
59 /* pps_register_source - add a PPS source in the system
60 * @info: the PPS info struct
61 * @default_params: the default PPS parameters of the new source
63 * This function is used to add a new PPS source in the system. The new
64 * source is described by info's fields and it will have, as default PPS
65 * parameters, the ones specified into default_params.
67 * The function returns, in case of success, the PPS device. Otherwise NULL.
70 struct pps_device *pps_register_source(struct pps_source_info *info,
71 int default_params)
73 struct pps_device *pps;
74 int err;
76 /* Sanity checks */
77 if ((info->mode & default_params) != default_params) {
78 pr_err("%s: unsupported default parameters\n",
79 info->name);
80 err = -EINVAL;
81 goto pps_register_source_exit;
83 if ((info->mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) != 0 &&
84 info->echo == NULL) {
85 pr_err("%s: echo function is not defined\n",
86 info->name);
87 err = -EINVAL;
88 goto pps_register_source_exit;
90 if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
91 pr_err("%s: unspecified time format\n",
92 info->name);
93 err = -EINVAL;
94 goto pps_register_source_exit;
97 /* Allocate memory for the new PPS source struct */
98 pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
99 if (pps == NULL) {
100 err = -ENOMEM;
101 goto pps_register_source_exit;
104 /* These initializations must be done before calling idr_get_new()
105 * in order to avoid reces into pps_event().
107 pps->params.api_version = PPS_API_VERS;
108 pps->params.mode = default_params;
109 pps->info = *info;
111 init_waitqueue_head(&pps->queue);
112 spin_lock_init(&pps->lock);
114 /* Create the char device */
115 err = pps_register_cdev(pps);
116 if (err < 0) {
117 pr_err("%s: unable to create char device\n",
118 info->name);
119 goto kfree_pps;
122 dev_info(pps->dev, "new PPS source %s\n", info->name);
124 return pps;
126 kfree_pps:
127 kfree(pps);
129 pps_register_source_exit:
130 pr_err("%s: unable to register source\n", info->name);
132 return NULL;
134 EXPORT_SYMBOL(pps_register_source);
136 /* pps_unregister_source - remove a PPS source from the system
137 * @pps: the PPS source
139 * This function is used to remove a previously registered PPS source from
140 * the system.
143 void pps_unregister_source(struct pps_device *pps)
145 pps_kc_remove(pps);
146 pps_unregister_cdev(pps);
148 /* don't have to kfree(pps) here because it will be done on
149 * device destruction */
151 EXPORT_SYMBOL(pps_unregister_source);
153 /* pps_event - register a PPS event into the system
154 * @pps: the PPS device
155 * @ts: the event timestamp
156 * @event: the event type
157 * @data: userdef pointer
159 * This function is used by each PPS client in order to register a new
160 * PPS event into the system (it's usually called inside an IRQ handler).
162 * If an echo function is associated with the PPS device it will be called
163 * as:
164 * pps->info.echo(pps, event, data);
166 void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
167 void *data)
169 unsigned long flags;
170 int captured = 0;
171 struct pps_ktime ts_real = { .sec = 0, .nsec = 0, .flags = 0 };
173 /* check event type */
174 BUG_ON((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0);
176 dev_dbg(pps->dev, "PPS event at %ld.%09ld\n",
177 ts->ts_real.tv_sec, ts->ts_real.tv_nsec);
179 timespec_to_pps_ktime(&ts_real, ts->ts_real);
181 spin_lock_irqsave(&pps->lock, flags);
183 /* Must call the echo function? */
184 if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
185 pps->info.echo(pps, event, data);
187 /* Check the event */
188 pps->current_mode = pps->params.mode;
189 if (event & pps->params.mode & PPS_CAPTUREASSERT) {
190 /* We have to add an offset? */
191 if (pps->params.mode & PPS_OFFSETASSERT)
192 pps_add_offset(&ts_real,
193 &pps->params.assert_off_tu);
195 /* Save the time stamp */
196 pps->assert_tu = ts_real;
197 pps->assert_sequence++;
198 dev_dbg(pps->dev, "capture assert seq #%u\n",
199 pps->assert_sequence);
201 captured = ~0;
203 if (event & pps->params.mode & PPS_CAPTURECLEAR) {
204 /* We have to add an offset? */
205 if (pps->params.mode & PPS_OFFSETCLEAR)
206 pps_add_offset(&ts_real,
207 &pps->params.clear_off_tu);
209 /* Save the time stamp */
210 pps->clear_tu = ts_real;
211 pps->clear_sequence++;
212 dev_dbg(pps->dev, "capture clear seq #%u\n",
213 pps->clear_sequence);
215 captured = ~0;
218 pps_kc_event(pps, ts, event);
220 /* Wake up if captured something */
221 if (captured) {
222 pps->last_ev++;
223 wake_up_interruptible_all(&pps->queue);
225 kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
228 spin_unlock_irqrestore(&pps->lock, flags);
230 EXPORT_SYMBOL(pps_event);