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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | // SPDX-License-Identifier: GPL-2.0-or-later /* * pps-ldisc.c -- PPS line discipline * * Copyright (C) 2008 Rodolfo Giometti <giometti@linux.it> */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/serial_core.h> #include <linux/tty.h> #include <linux/pps_kernel.h> #include <linux/bug.h> static void pps_tty_dcd_change(struct tty_struct *tty, bool active) { struct pps_device *pps; struct pps_event_time ts; pps_get_ts(&ts); 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, active ? PPS_CAPTUREASSERT : PPS_CAPTURECLEAR, NULL); dev_dbg(pps->dev, "PPS %s at %lu\n", active ? "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 (IS_ERR(pps)) { pr_err("cannot register PPS source \"%s\"\n", info.path); return PTR_ERR(pps); } 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.num = N_PPS; 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(&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) { tty_unregister_ldisc(&pps_ldisc_ops); } 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"); |