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1/*
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24#include <linux/module.h>
25#include <linux/serial_core.h>
26#include <linux/tty.h>
27#include <linux/pps_kernel.h>
28#include <linux/bug.h>
29
30#define PPS_TTY_MAGIC 0x0001
31
32static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status)
33{
34 struct pps_device *pps;
35 struct pps_event_time ts;
36
37 pps_get_ts(&ts);
38
39 pps = pps_lookup_dev(tty);
40 /*
41 * This should never fail, but the ldisc locking is very
42 * convoluted, so don't crash just in case.
43 */
44 if (WARN_ON_ONCE(pps == NULL))
45 return;
46
47 /* Now do the PPS event report */
48 pps_event(pps, &ts, status ? PPS_CAPTUREASSERT :
49 PPS_CAPTURECLEAR, NULL);
50
51 dev_dbg(pps->dev, "PPS %s at %lu\n",
52 status ? "assert" : "clear", jiffies);
53}
54
55static int (*alias_n_tty_open)(struct tty_struct *tty);
56
57static int pps_tty_open(struct tty_struct *tty)
58{
59 struct pps_source_info info;
60 struct tty_driver *drv = tty->driver;
61 int index = tty->index + drv->name_base;
62 struct pps_device *pps;
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 pps = pps_register_source(&info, PPS_CAPTUREBOTH | \
74 PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
75 if (pps == NULL) {
76 pr_err("cannot register PPS source \"%s\"\n", info.path);
77 return -ENOMEM;
78 }
79 pps->lookup_cookie = tty;
80
81 /* Now open the base class N_TTY ldisc */
82 ret = alias_n_tty_open(tty);
83 if (ret < 0) {
84 pr_err("cannot open tty ldisc \"%s\"\n", info.path);
85 goto err_unregister;
86 }
87
88 dev_info(pps->dev, "source \"%s\" added\n", info.path);
89
90 return 0;
91
92err_unregister:
93 pps_unregister_source(pps);
94 return ret;
95}
96
97static void (*alias_n_tty_close)(struct tty_struct *tty);
98
99static void pps_tty_close(struct tty_struct *tty)
100{
101 struct pps_device *pps = pps_lookup_dev(tty);
102
103 alias_n_tty_close(tty);
104
105 if (WARN_ON(!pps))
106 return;
107
108 dev_info(pps->dev, "removed\n");
109 pps_unregister_source(pps);
110}
111
112static struct tty_ldisc_ops pps_ldisc_ops;
113
114/*
115 * Module stuff
116 */
117
118static int __init pps_tty_init(void)
119{
120 int err;
121
122 /* Inherit the N_TTY's ops */
123 n_tty_inherit_ops(&pps_ldisc_ops);
124
125 /* Save N_TTY's open()/close() methods */
126 alias_n_tty_open = pps_ldisc_ops.open;
127 alias_n_tty_close = pps_ldisc_ops.close;
128
129 /* Init PPS_TTY data */
130 pps_ldisc_ops.owner = THIS_MODULE;
131 pps_ldisc_ops.magic = PPS_TTY_MAGIC;
132 pps_ldisc_ops.name = "pps_tty";
133 pps_ldisc_ops.dcd_change = pps_tty_dcd_change;
134 pps_ldisc_ops.open = pps_tty_open;
135 pps_ldisc_ops.close = pps_tty_close;
136
137 err = tty_register_ldisc(N_PPS, &pps_ldisc_ops);
138 if (err)
139 pr_err("can't register PPS line discipline\n");
140 else
141 pr_info("PPS line discipline registered\n");
142
143 return err;
144}
145
146static void __exit pps_tty_cleanup(void)
147{
148 int err;
149
150 err = tty_unregister_ldisc(N_PPS);
151 if (err)
152 pr_err("can't unregister PPS line discipline\n");
153 else
154 pr_info("PPS line discipline removed\n");
155}
156
157module_init(pps_tty_init);
158module_exit(pps_tty_cleanup);
159
160MODULE_ALIAS_LDISC(N_PPS);
161MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
162MODULE_DESCRIPTION("PPS TTY device driver");
163MODULE_LICENSE("GPL");
1/*
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24#include <linux/module.h>
25#include <linux/serial_core.h>
26#include <linux/tty.h>
27#include <linux/pps_kernel.h>
28#include <linux/bug.h>
29
30#define PPS_TTY_MAGIC 0x0001
31
32static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status)
33{
34 struct pps_device *pps;
35 struct pps_event_time ts;
36
37 pps_get_ts(&ts);
38
39 pps = pps_lookup_dev(tty);
40 /*
41 * This should never fail, but the ldisc locking is very
42 * convoluted, so don't crash just in case.
43 */
44 if (WARN_ON_ONCE(pps == NULL))
45 return;
46
47 /* Now do the PPS event report */
48 pps_event(pps, &ts, status ? PPS_CAPTUREASSERT :
49 PPS_CAPTURECLEAR, NULL);
50
51 dev_dbg(pps->dev, "PPS %s at %lu\n",
52 status ? "assert" : "clear", jiffies);
53}
54
55static int (*alias_n_tty_open)(struct tty_struct *tty);
56
57static int pps_tty_open(struct tty_struct *tty)
58{
59 struct pps_source_info info;
60 struct tty_driver *drv = tty->driver;
61 int index = tty->index + drv->name_base;
62 struct pps_device *pps;
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 pps = pps_register_source(&info, PPS_CAPTUREBOTH | \
74 PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
75 if (pps == NULL) {
76 pr_err("cannot register PPS source \"%s\"\n", info.path);
77 return -ENOMEM;
78 }
79 pps->lookup_cookie = tty;
80
81 /* Now open the base class N_TTY ldisc */
82 ret = alias_n_tty_open(tty);
83 if (ret < 0) {
84 pr_err("cannot open tty ldisc \"%s\"\n", info.path);
85 goto err_unregister;
86 }
87
88 dev_info(pps->dev, "source \"%s\" added\n", info.path);
89
90 return 0;
91
92err_unregister:
93 pps_unregister_source(pps);
94 return ret;
95}
96
97static void (*alias_n_tty_close)(struct tty_struct *tty);
98
99static void pps_tty_close(struct tty_struct *tty)
100{
101 struct pps_device *pps = pps_lookup_dev(tty);
102
103 alias_n_tty_close(tty);
104
105 if (WARN_ON(!pps))
106 return;
107
108 dev_info(pps->dev, "removed\n");
109 pps_unregister_source(pps);
110}
111
112static struct tty_ldisc_ops pps_ldisc_ops;
113
114/*
115 * Module stuff
116 */
117
118static int __init pps_tty_init(void)
119{
120 int err;
121
122 /* Inherit the N_TTY's ops */
123 n_tty_inherit_ops(&pps_ldisc_ops);
124
125 /* Save N_TTY's open()/close() methods */
126 alias_n_tty_open = pps_ldisc_ops.open;
127 alias_n_tty_close = pps_ldisc_ops.close;
128
129 /* Init PPS_TTY data */
130 pps_ldisc_ops.owner = THIS_MODULE;
131 pps_ldisc_ops.magic = PPS_TTY_MAGIC;
132 pps_ldisc_ops.name = "pps_tty";
133 pps_ldisc_ops.dcd_change = pps_tty_dcd_change;
134 pps_ldisc_ops.open = pps_tty_open;
135 pps_ldisc_ops.close = pps_tty_close;
136
137 err = tty_register_ldisc(N_PPS, &pps_ldisc_ops);
138 if (err)
139 pr_err("can't register PPS line discipline\n");
140 else
141 pr_info("PPS line discipline registered\n");
142
143 return err;
144}
145
146static void __exit pps_tty_cleanup(void)
147{
148 int err;
149
150 err = tty_unregister_ldisc(N_PPS);
151 if (err)
152 pr_err("can't unregister PPS line discipline\n");
153 else
154 pr_info("PPS line discipline removed\n");
155}
156
157module_init(pps_tty_init);
158module_exit(pps_tty_cleanup);
159
160MODULE_ALIAS_LDISC(N_PPS);
161MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
162MODULE_DESCRIPTION("PPS TTY device driver");
163MODULE_LICENSE("GPL");