/* * pps-ldisc.c -- PPS line discipline * * * Copyright (C) 2008 Rodolfo Giometti <giometti@linux.it> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include <linux/module.h> #include <linux/serial_core.h> #include <linux/tty.h> #include <linux/pps_kernel.h> #define PPS_TTY_MAGIC 0x0001 static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status, struct timespec *ts) { int id = (long)tty->disc_data; struct timespec __ts; struct pps_ktime pps_ts; /* First of all we get the time stamp... */ getnstimeofday(&__ts); /* Does caller give us a timestamp? */ if (ts) { /* Yes. Let's use it! */ pps_ts.sec = ts->tv_sec; pps_ts.nsec = ts->tv_nsec; } else { /* No. Do it ourself! */ pps_ts.sec = __ts.tv_sec; pps_ts.nsec = __ts.tv_nsec; } /* Now do the PPS event report */ pps_event(id, &pps_ts, status ? PPS_CAPTUREASSERT : PPS_CAPTURECLEAR, NULL); pr_debug("PPS %s at %lu on source #%d\n", status ? "assert" : "clear", jiffies, id); } static int (*alias_n_tty_open)(struct tty_struct *tty); static int pps_tty_open(struct tty_struct *tty) { struct pps_source_info info; struct tty_driver *drv = tty->driver; int index = tty->index + drv->name_base; int ret; info.owner = THIS_MODULE; info.dev = NULL; snprintf(info.name, PPS_MAX_NAME_LEN, "%s%d", drv->driver_name, index); snprintf(info.path, PPS_MAX_NAME_LEN, "/dev/%s%d", drv->name, index); info.mode = PPS_CAPTUREBOTH | \ PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \ PPS_CANWAIT | PPS_TSFMT_TSPEC; ret = pps_register_source(&info, PPS_CAPTUREBOTH | \ PPS_OFFSETASSERT | PPS_OFFSETCLEAR); if (ret < 0) { pr_err("cannot register PPS source \"%s\"\n", info.path); return ret; } tty->disc_data = (void *)(long)ret; /* Should open N_TTY ldisc too */ ret = alias_n_tty_open(tty); if (ret < 0) pps_unregister_source((long)tty->disc_data); pr_info("PPS source #%d \"%s\" added\n", ret, info.path); return 0; } static void (*alias_n_tty_close)(struct tty_struct *tty); static void pps_tty_close(struct tty_struct *tty) { int id = (long)tty->disc_data; pps_unregister_source(id); alias_n_tty_close(tty); pr_info("PPS source #%d removed\n", id); } static struct tty_ldisc_ops pps_ldisc_ops; /* * Module stuff */ static int __init pps_tty_init(void) { int err; /* Inherit the N_TTY's ops */ n_tty_inherit_ops(&pps_ldisc_ops); /* Save N_TTY's open()/close() methods */ alias_n_tty_open = pps_ldisc_ops.open; alias_n_tty_close = pps_ldisc_ops.close; /* Init PPS_TTY data */ pps_ldisc_ops.owner = THIS_MODULE; pps_ldisc_ops.magic = PPS_TTY_MAGIC; pps_ldisc_ops.name = "pps_tty"; pps_ldisc_ops.dcd_change = pps_tty_dcd_change; pps_ldisc_ops.open = pps_tty_open; pps_ldisc_ops.close = pps_tty_close; err = tty_register_ldisc(N_PPS, &pps_ldisc_ops); if (err) pr_err("can't register PPS line discipline\n"); else pr_info("PPS line discipline registered\n"); return err; } static void __exit pps_tty_cleanup(void) { int err; err = tty_unregister_ldisc(N_PPS); if (err) pr_err("can't unregister PPS line discipline\n"); else pr_info("PPS line discipline removed\n"); } module_init(pps_tty_init); module_exit(pps_tty_cleanup); MODULE_ALIAS_LDISC(N_PPS); MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); MODULE_DESCRIPTION("PPS TTY device driver"); MODULE_LICENSE("GPL");