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/drivers/pps/kapi.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 230 lines | 123 code | 36 blank | 71 comment | 19 complexity | ce0bb3d155e7d0d74f15cdb1f1c5b7ea MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  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
 55/*
 56 * Exported functions
 57 */
 58
 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
 62 *
 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.
 66 *
 67 * The function returns, in case of success, the PPS device. Otherwise NULL.
 68 */
 69
 70struct pps_device *pps_register_source(struct pps_source_info *info,
 71		int default_params)
 72{
 73	struct pps_device *pps;
 74	int err;
 75
 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;
 82	}
 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;
 89	}
 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;
 95	}
 96
 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;
102	}
103
104	/* These initializations must be done before calling idr_get_new()
105	 * in order to avoid reces into pps_event().
106	 */
107	pps->params.api_version = PPS_API_VERS;
108	pps->params.mode = default_params;
109	pps->info = *info;
110
111	init_waitqueue_head(&pps->queue);
112	spin_lock_init(&pps->lock);
113
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;
120	}
121
122	dev_info(pps->dev, "new PPS source %s\n", info->name);
123
124	return pps;
125
126kfree_pps:
127	kfree(pps);
128
129pps_register_source_exit:
130	pr_err("%s: unable to register source\n", info->name);
131
132	return NULL;
133}
134EXPORT_SYMBOL(pps_register_source);
135
136/* pps_unregister_source - remove a PPS source from the system
137 * @pps: the PPS source
138 *
139 * This function is used to remove a previously registered PPS source from
140 * the system.
141 */
142
143void pps_unregister_source(struct pps_device *pps)
144{
145	pps_kc_remove(pps);
146	pps_unregister_cdev(pps);
147
148	/* don't have to kfree(pps) here because it will be done on
149	 * device destruction */
150}
151EXPORT_SYMBOL(pps_unregister_source);
152
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
158 *
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).
161 *
162 * If an echo function is associated with the PPS device it will be called
163 * as:
164 *	pps->info.echo(pps, event, data);
165 */
166void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
167		void *data)
168{
169	unsigned long flags;
170	int captured = 0;
171	struct pps_ktime ts_real = { .sec = 0, .nsec = 0, .flags = 0 };
172
173	/* check event type */
174	BUG_ON((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0);
175
176	dev_dbg(pps->dev, "PPS event at %ld.%09ld\n",
177			ts->ts_real.tv_sec, ts->ts_real.tv_nsec);
178
179	timespec_to_pps_ktime(&ts_real, ts->ts_real);
180
181	spin_lock_irqsave(&pps->lock, flags);
182
183	/* Must call the echo function? */
184	if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
185		pps->info.echo(pps, event, data);
186
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);
194
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);
200
201		captured = ~0;
202	}
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);
208
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);
214
215		captured = ~0;
216	}
217
218	pps_kc_event(pps, ts, event);
219
220	/* Wake up if captured something */
221	if (captured) {
222		pps->last_ev++;
223		wake_up_interruptible_all(&pps->queue);
224
225		kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
226	}
227
228	spin_unlock_irqrestore(&pps->lock, flags);
229}
230EXPORT_SYMBOL(pps_event);