blob: 8e1932d29fd4b1ee2d5ef1320846a56010d09909 [file] [log] [blame]
Rodolfo Giomettia0880df2010-03-10 15:23:47 -08001/*
2 * pps-ldisc.c -- PPS line discipline
3 *
4 *
5 * Copyright (C) 2008 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#include <linux/module.h>
23#include <linux/serial_core.h>
24#include <linux/tty.h>
25#include <linux/pps_kernel.h>
26
27#define PPS_TTY_MAGIC 0x0001
28
29static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status,
30 struct timespec *ts)
31{
32 int id = (long)tty->disc_data;
33 struct timespec __ts;
34 struct pps_ktime pps_ts;
35
36 /* First of all we get the time stamp... */
37 getnstimeofday(&__ts);
38
39 /* Does caller give us a timestamp? */
40 if (ts) { /* Yes. Let's use it! */
41 pps_ts.sec = ts->tv_sec;
42 pps_ts.nsec = ts->tv_nsec;
43 } else { /* No. Do it ourself! */
44 pps_ts.sec = __ts.tv_sec;
45 pps_ts.nsec = __ts.tv_nsec;
46 }
47
48 /* Now do the PPS event report */
49 pps_event(id, &pps_ts, status ? PPS_CAPTUREASSERT : PPS_CAPTURECLEAR,
50 NULL);
51
52 pr_debug("PPS %s at %lu on source #%d\n",
53 status ? "assert" : "clear", jiffies, id);
54}
55
56static int (*alias_n_tty_open)(struct tty_struct *tty);
57
58static int pps_tty_open(struct tty_struct *tty)
59{
60 struct pps_source_info info;
61 struct tty_driver *drv = tty->driver;
62 int index = tty->index + drv->name_base;
63 int ret;
64
65 info.owner = THIS_MODULE;
66 info.dev = NULL;
67 snprintf(info.name, PPS_MAX_NAME_LEN, "%s%d", drv->driver_name, index);
68 snprintf(info.path, PPS_MAX_NAME_LEN, "/dev/%s%d", drv->name, index);
69 info.mode = PPS_CAPTUREBOTH | \
70 PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
71 PPS_CANWAIT | PPS_TSFMT_TSPEC;
72
73 ret = pps_register_source(&info, PPS_CAPTUREBOTH | \
74 PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
75 if (ret < 0) {
76 pr_err("cannot register PPS source \"%s\"\n", info.path);
77 return ret;
78 }
79 tty->disc_data = (void *)(long)ret;
80
81 /* Should open N_TTY ldisc too */
82 ret = alias_n_tty_open(tty);
83 if (ret < 0)
84 pps_unregister_source((long)tty->disc_data);
85
86 pr_info("PPS source #%d \"%s\" added\n", ret, info.path);
87
88 return 0;
89}
90
91static void (*alias_n_tty_close)(struct tty_struct *tty);
92
93static void pps_tty_close(struct tty_struct *tty)
94{
95 int id = (long)tty->disc_data;
96
97 pps_unregister_source(id);
98 alias_n_tty_close(tty);
99
100 pr_info("PPS source #%d removed\n", id);
101}
102
103static struct tty_ldisc_ops pps_ldisc_ops;
104
105/*
106 * Module stuff
107 */
108
109static int __init pps_tty_init(void)
110{
111 int err;
112
113 /* Inherit the N_TTY's ops */
114 n_tty_inherit_ops(&pps_ldisc_ops);
115
116 /* Save N_TTY's open()/close() methods */
117 alias_n_tty_open = pps_ldisc_ops.open;
118 alias_n_tty_close = pps_ldisc_ops.close;
119
120 /* Init PPS_TTY data */
121 pps_ldisc_ops.owner = THIS_MODULE;
122 pps_ldisc_ops.magic = PPS_TTY_MAGIC;
123 pps_ldisc_ops.name = "pps_tty";
124 pps_ldisc_ops.dcd_change = pps_tty_dcd_change;
125 pps_ldisc_ops.open = pps_tty_open;
126 pps_ldisc_ops.close = pps_tty_close;
127
128 err = tty_register_ldisc(N_PPS, &pps_ldisc_ops);
129 if (err)
130 pr_err("can't register PPS line discipline\n");
131 else
132 pr_info("PPS line discipline registered\n");
133
134 return err;
135}
136
137static void __exit pps_tty_cleanup(void)
138{
139 int err;
140
141 err = tty_unregister_ldisc(N_PPS);
142 if (err)
143 pr_err("can't unregister PPS line discipline\n");
144 else
145 pr_info("PPS line discipline removed\n");
146}
147
148module_init(pps_tty_init);
149module_exit(pps_tty_cleanup);
150
151MODULE_ALIAS_LDISC(N_PPS);
152MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
153MODULE_DESCRIPTION("PPS TTY device driver");
154MODULE_LICENSE("GPL");