Linux Kernel  3.7.1
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kapi.c
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1 /*
2  * kernel API
3  *
4  *
5  * Copyright (C) 2005-2009 Rodolfo Giometti <[email protected]>
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 
41 static 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 static 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 
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 
132 kfree_pps:
133  kfree(pps);
134 
135 pps_register_source_exit:
136  pr_err("%s: unable to register source\n", info->name);
137 
138  return NULL;
139 }
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 
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 }
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  */
172 void 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++;
230 
232  }
233 
234  spin_unlock_irqrestore(&pps->lock, flags);
235 }