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#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"); 155