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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * pps-ldisc.c -- PPS line discipline
4 *
5 * Copyright (C) 2008 Rodolfo Giometti <giometti@linux.it>
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/module.h>
11#include <linux/serial_core.h>
12#include <linux/tty.h>
13#include <linux/pps_kernel.h>
14#include <linux/bug.h>
15
16static void pps_tty_dcd_change(struct tty_struct *tty, bool active)
17{
18 struct pps_device *pps;
19 struct pps_event_time ts;
20
21 pps_get_ts(&ts);
22
23 pps = pps_lookup_dev(tty);
24 /*
25 * This should never fail, but the ldisc locking is very
26 * convoluted, so don't crash just in case.
27 */
28 if (WARN_ON_ONCE(pps == NULL))
29 return;
30
31 /* Now do the PPS event report */
32 pps_event(pps, &ts, active ? PPS_CAPTUREASSERT :
33 PPS_CAPTURECLEAR, NULL);
34
35 dev_dbg(pps->dev, "PPS %s at %lu\n",
36 active ? "assert" : "clear", jiffies);
37}
38
39static int (*alias_n_tty_open)(struct tty_struct *tty);
40
41static int pps_tty_open(struct tty_struct *tty)
42{
43 struct pps_source_info info;
44 struct tty_driver *drv = tty->driver;
45 int index = tty->index + drv->name_base;
46 struct pps_device *pps;
47 int ret;
48
49 info.owner = THIS_MODULE;
50 info.dev = NULL;
51 snprintf(info.name, PPS_MAX_NAME_LEN, "%s%d", drv->driver_name, index);
52 snprintf(info.path, PPS_MAX_NAME_LEN, "/dev/%s%d", drv->name, index);
53 info.mode = PPS_CAPTUREBOTH | \
54 PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
55 PPS_CANWAIT | PPS_TSFMT_TSPEC;
56
57 pps = pps_register_source(&info, PPS_CAPTUREBOTH | \
58 PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
59 if (IS_ERR(pps)) {
60 pr_err("cannot register PPS source \"%s\"\n", info.path);
61 return PTR_ERR(pps);
62 }
63 pps->lookup_cookie = tty;
64
65 /* Now open the base class N_TTY ldisc */
66 ret = alias_n_tty_open(tty);
67 if (ret < 0) {
68 pr_err("cannot open tty ldisc \"%s\"\n", info.path);
69 goto err_unregister;
70 }
71
72 dev_info(pps->dev, "source \"%s\" added\n", info.path);
73
74 return 0;
75
76err_unregister:
77 pps_unregister_source(pps);
78 return ret;
79}
80
81static void (*alias_n_tty_close)(struct tty_struct *tty);
82
83static void pps_tty_close(struct tty_struct *tty)
84{
85 struct pps_device *pps = pps_lookup_dev(tty);
86
87 alias_n_tty_close(tty);
88
89 if (WARN_ON(!pps))
90 return;
91
92 dev_info(pps->dev, "removed\n");
93 pps_unregister_source(pps);
94}
95
96static struct tty_ldisc_ops pps_ldisc_ops;
97
98/*
99 * Module stuff
100 */
101
102static int __init pps_tty_init(void)
103{
104 int err;
105
106 /* Inherit the N_TTY's ops */
107 n_tty_inherit_ops(&pps_ldisc_ops);
108
109 /* Save N_TTY's open()/close() methods */
110 alias_n_tty_open = pps_ldisc_ops.open;
111 alias_n_tty_close = pps_ldisc_ops.close;
112
113 /* Init PPS_TTY data */
114 pps_ldisc_ops.owner = THIS_MODULE;
115 pps_ldisc_ops.num = N_PPS;
116 pps_ldisc_ops.name = "pps_tty";
117 pps_ldisc_ops.dcd_change = pps_tty_dcd_change;
118 pps_ldisc_ops.open = pps_tty_open;
119 pps_ldisc_ops.close = pps_tty_close;
120
121 err = tty_register_ldisc(&pps_ldisc_ops);
122 if (err)
123 pr_err("can't register PPS line discipline\n");
124 else
125 pr_info("PPS line discipline registered\n");
126
127 return err;
128}
129
130static void __exit pps_tty_cleanup(void)
131{
132 tty_unregister_ldisc(&pps_ldisc_ops);
133}
134
135module_init(pps_tty_init);
136module_exit(pps_tty_cleanup);
137
138MODULE_ALIAS_LDISC(N_PPS);
139MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
140MODULE_DESCRIPTION("PPS TTY device driver");
141MODULE_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
29#define PPS_TTY_MAGIC 0x0001
30
31static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status,
32 struct pps_event_time *ts)
33{
34 struct pps_device *pps = (struct pps_device *)tty->disc_data;
35
36 BUG_ON(pps == NULL);
37
38 /* Now do the PPS event report */
39 pps_event(pps, ts, status ? PPS_CAPTUREASSERT :
40 PPS_CAPTURECLEAR, NULL);
41
42 dev_dbg(pps->dev, "PPS %s at %lu\n",
43 status ? "assert" : "clear", jiffies);
44}
45
46static int (*alias_n_tty_open)(struct tty_struct *tty);
47
48static int pps_tty_open(struct tty_struct *tty)
49{
50 struct pps_source_info info;
51 struct tty_driver *drv = tty->driver;
52 int index = tty->index + drv->name_base;
53 struct pps_device *pps;
54 int ret;
55
56 info.owner = THIS_MODULE;
57 info.dev = NULL;
58 snprintf(info.name, PPS_MAX_NAME_LEN, "%s%d", drv->driver_name, index);
59 snprintf(info.path, PPS_MAX_NAME_LEN, "/dev/%s%d", drv->name, index);
60 info.mode = PPS_CAPTUREBOTH | \
61 PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
62 PPS_CANWAIT | PPS_TSFMT_TSPEC;
63
64 pps = pps_register_source(&info, PPS_CAPTUREBOTH | \
65 PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
66 if (pps == NULL) {
67 pr_err("cannot register PPS source \"%s\"\n", info.path);
68 return -ENOMEM;
69 }
70 tty->disc_data = pps;
71
72 /* Should open N_TTY ldisc too */
73 ret = alias_n_tty_open(tty);
74 if (ret < 0) {
75 pr_err("cannot open tty ldisc \"%s\"\n", info.path);
76 goto err_unregister;
77 }
78
79 dev_info(pps->dev, "source \"%s\" added\n", info.path);
80
81 return 0;
82
83err_unregister:
84 tty->disc_data = NULL;
85 pps_unregister_source(pps);
86 return ret;
87}
88
89static void (*alias_n_tty_close)(struct tty_struct *tty);
90
91static void pps_tty_close(struct tty_struct *tty)
92{
93 struct pps_device *pps = (struct pps_device *)tty->disc_data;
94
95 alias_n_tty_close(tty);
96
97 tty->disc_data = NULL;
98 dev_info(pps->dev, "removed\n");
99 pps_unregister_source(pps);
100}
101
102static struct tty_ldisc_ops pps_ldisc_ops;
103
104/*
105 * Module stuff
106 */
107
108static int __init pps_tty_init(void)
109{
110 int err;
111
112 /* Inherit the N_TTY's ops */
113 n_tty_inherit_ops(&pps_ldisc_ops);
114
115 /* Save N_TTY's open()/close() methods */
116 alias_n_tty_open = pps_ldisc_ops.open;
117 alias_n_tty_close = pps_ldisc_ops.close;
118
119 /* Init PPS_TTY data */
120 pps_ldisc_ops.owner = THIS_MODULE;
121 pps_ldisc_ops.magic = PPS_TTY_MAGIC;
122 pps_ldisc_ops.name = "pps_tty";
123 pps_ldisc_ops.dcd_change = pps_tty_dcd_change;
124 pps_ldisc_ops.open = pps_tty_open;
125 pps_ldisc_ops.close = pps_tty_close;
126
127 err = tty_register_ldisc(N_PPS, &pps_ldisc_ops);
128 if (err)
129 pr_err("can't register PPS line discipline\n");
130 else
131 pr_info("PPS line discipline registered\n");
132
133 return err;
134}
135
136static void __exit pps_tty_cleanup(void)
137{
138 int err;
139
140 err = tty_unregister_ldisc(N_PPS);
141 if (err)
142 pr_err("can't unregister PPS line discipline\n");
143 else
144 pr_info("PPS line discipline removed\n");
145}
146
147module_init(pps_tty_init);
148module_exit(pps_tty_cleanup);
149
150MODULE_ALIAS_LDISC(N_PPS);
151MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
152MODULE_DESCRIPTION("PPS TTY device driver");
153MODULE_LICENSE("GPL");