diff options
Diffstat (limited to 'drivers/pps/clients/pps-ldisc.c')
| -rw-r--r-- | drivers/pps/clients/pps-ldisc.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/drivers/pps/clients/pps-ldisc.c b/drivers/pps/clients/pps-ldisc.c new file mode 100644 index 0000000000..443d6bae19 --- /dev/null +++ b/drivers/pps/clients/pps-ldisc.c @@ -0,0 +1,141 @@ +// 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"); |