/* * pps-ldisc.c -- PPS line discipline * * * Copyright (C) 2008 Rodolfo Giometti * * 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. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #define PPS_TTY_MAGIC 0x0001 static void pps_tty_dcd_change(struct tty_struct *tty, unsigned int status, struct pps_event_time *ts) { struct pps_device *pps = pps_lookup_dev(tty); /* * This should never fail, but the ldisc locking is very * convoluted, so don't crash just in case. */ if (WARN_ON_ONCE(pps == NULL)) return; /* Now do the PPS event report */ pps_event(pps, ts, status ? PPS_CAPTUREASSERT : PPS_CAPTURECLEAR, NULL); dev_dbg(pps->dev, "PPS %s at %lu\n", status ? "assert" : "clear", jiffies); } 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; struct pps_device *pps; 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; pps = pps_register_source(&info, PPS_CAPTUREBOTH | \ PPS_OFFSETASSERT | PPS_OFFSETCLEAR); if (pps == NULL) { pr_err("cannot register PPS source \"%s\"\n", info.path); return -ENOMEM; } pps->lookup_cookie = tty; /* Now open the base class N_TTY ldisc */ ret = alias_n_tty_open(tty); if (ret < 0) { pr_err("cannot open tty ldisc \"%s\"\n", info.path); goto err_unregister; } dev_info(pps->dev, "source \"%s\" added\n", info.path); return 0; err_unregister: pps_unregister_source(pps); return ret; } static void (*alias_n_tty_close)(struct tty_struct *tty); static void pps_tty_close(struct tty_struct *tty) { struct pps_device *pps = pps_lookup_dev(tty); alias_n_tty_close(tty); if (WARN_ON(!pps)) return; dev_info(pps->dev, "removed\n"); pps_unregister_source(pps); } 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 "); MODULE_DESCRIPTION("PPS TTY device driver"); MODULE_LICENSE("GPL");