Commit | Line | Data |
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a0880df0 RG |
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 | ||
7f7cce74 AG |
22 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
23 | ||
a0880df0 RG |
24 | #include <linux/module.h> |
25 | #include <linux/serial_core.h> | |
26 | #include <linux/tty.h> | |
27 | #include <linux/pps_kernel.h> | |
ce3da1a6 | 28 | #include <linux/bug.h> |
a0880df0 RG |
29 | |
30 | #define PPS_TTY_MAGIC 0x0001 | |
31 | ||
593fb1ae | 32 | static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status) |
a0880df0 | 33 | { |
593fb1ae GS |
34 | struct pps_device *pps; |
35 | struct pps_event_time ts; | |
36 | ||
37 | pps_get_ts(&ts); | |
a0880df0 | 38 | |
593fb1ae | 39 | pps = pps_lookup_dev(tty); |
ce3da1a6 GS |
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; | |
5e196d34 | 46 | |
a0880df0 | 47 | /* Now do the PPS event report */ |
593fb1ae | 48 | pps_event(pps, &ts, status ? PPS_CAPTUREASSERT : |
5e196d34 | 49 | PPS_CAPTURECLEAR, NULL); |
a0880df0 | 50 | |
5e196d34 AG |
51 | dev_dbg(pps->dev, "PPS %s at %lu\n", |
52 | status ? "assert" : "clear", jiffies); | |
a0880df0 RG |
53 | } |
54 | ||
55 | static int (*alias_n_tty_open)(struct tty_struct *tty); | |
56 | ||
57 | static 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; | |
5e196d34 | 62 | struct pps_device *pps; |
a0880df0 RG |
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 | ||
5e196d34 | 73 | pps = pps_register_source(&info, PPS_CAPTUREBOTH | \ |
a0880df0 | 74 | PPS_OFFSETASSERT | PPS_OFFSETCLEAR); |
5e196d34 | 75 | if (pps == NULL) { |
a0880df0 | 76 | pr_err("cannot register PPS source \"%s\"\n", info.path); |
5e196d34 | 77 | return -ENOMEM; |
a0880df0 | 78 | } |
03a7ffe4 | 79 | pps->lookup_cookie = tty; |
a0880df0 | 80 | |
03a7ffe4 | 81 | /* Now open the base class N_TTY ldisc */ |
a0880df0 | 82 | ret = alias_n_tty_open(tty); |
5e196d34 AG |
83 | if (ret < 0) { |
84 | pr_err("cannot open tty ldisc \"%s\"\n", info.path); | |
85 | goto err_unregister; | |
86 | } | |
a0880df0 | 87 | |
5e196d34 | 88 | dev_info(pps->dev, "source \"%s\" added\n", info.path); |
a0880df0 RG |
89 | |
90 | return 0; | |
5e196d34 AG |
91 | |
92 | err_unregister: | |
5e196d34 AG |
93 | pps_unregister_source(pps); |
94 | return ret; | |
a0880df0 RG |
95 | } |
96 | ||
97 | static void (*alias_n_tty_close)(struct tty_struct *tty); | |
98 | ||
99 | static void pps_tty_close(struct tty_struct *tty) | |
100 | { | |
03a7ffe4 | 101 | struct pps_device *pps = pps_lookup_dev(tty); |
a0880df0 | 102 | |
a0880df0 RG |
103 | alias_n_tty_close(tty); |
104 | ||
ce3da1a6 GS |
105 | if (WARN_ON(!pps)) |
106 | return; | |
107 | ||
5e196d34 AG |
108 | dev_info(pps->dev, "removed\n"); |
109 | pps_unregister_source(pps); | |
a0880df0 RG |
110 | } |
111 | ||
112 | static struct tty_ldisc_ops pps_ldisc_ops; | |
113 | ||
114 | /* | |
115 | * Module stuff | |
116 | */ | |
117 | ||
118 | static 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 | ||
146 | static 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 | ||
157 | module_init(pps_tty_init); | |
158 | module_exit(pps_tty_cleanup); | |
159 | ||
160 | MODULE_ALIAS_LDISC(N_PPS); | |
161 | MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); | |
162 | MODULE_DESCRIPTION("PPS TTY device driver"); | |
163 | MODULE_LICENSE("GPL"); |