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