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nmdm.c
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Editing: nmdm.c
/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); /* * Pseudo-nulmodem driver * Mighty handy for use with serial console in Vmware */ #include <sys/param.h> #include <sys/systm.h> #include <sys/priv.h> #include <sys/proc.h> #include <sys/tty.h> #include <sys/conf.h> #include <sys/eventhandler.h> #include <sys/fcntl.h> #include <sys/poll.h> #include <sys/kernel.h> #include <sys/limits.h> #include <sys/module.h> #include <sys/serial.h> #include <sys/signalvar.h> #include <sys/malloc.h> #include <sys/taskqueue.h> static MALLOC_DEFINE(M_NMDM, "nullmodem", "nullmodem data structures"); static tsw_inwakeup_t nmdm_outwakeup; static tsw_outwakeup_t nmdm_inwakeup; static tsw_param_t nmdm_param; static tsw_modem_t nmdm_modem; static tsw_close_t nmdm_close; static tsw_free_t nmdm_free; static struct ttydevsw nmdm_class = { .tsw_flags = TF_NOPREFIX, .tsw_inwakeup = nmdm_inwakeup, .tsw_outwakeup = nmdm_outwakeup, .tsw_param = nmdm_param, .tsw_modem = nmdm_modem, .tsw_close = nmdm_close, .tsw_free = nmdm_free, }; static void nmdm_task_tty(void *, int); struct nmdmsoftc; struct nmdmpart { struct tty *np_tty; int np_dcd; struct task np_task; struct nmdmpart *np_other; struct nmdmsoftc *np_pair; struct callout np_callout; u_long np_quota; u_long np_accumulator; int np_rate; int np_credits; #define QS 8 /* Quota shift */ }; struct nmdmsoftc { struct nmdmpart ns_part1; struct nmdmpart ns_part2; struct mtx ns_mtx; }; static int nmdm_count = 0; static void nmdm_close(struct tty *tp) { struct nmdmpart *np; struct nmdmpart *onp; struct tty *otp; np = tty_softc(tp); onp = np->np_other; otp = onp->np_tty; /* If second part is opened, do not destroy ourselves. */ if (tty_opened(otp)) return; /* Shut down self. */ tty_rel_gone(tp); /* Shut down second part. */ tty_lock(tp); onp = np->np_other; if (onp == NULL) return; otp = onp->np_tty; tty_rel_gone(otp); tty_lock(tp); } static void nmdm_free(void *softc) { struct nmdmpart *np = (struct nmdmpart *)softc; struct nmdmsoftc *ns = np->np_pair; callout_drain(&np->np_callout); taskqueue_drain(taskqueue_swi, &np->np_task); /* * The function is called on both parts simultaneously. We serialize * with help of ns_mtx. The first invocation should return and * delegate freeing of resources to the second. */ mtx_lock(&ns->ns_mtx); if (np->np_other != NULL) { np->np_other->np_other = NULL; mtx_unlock(&ns->ns_mtx); return; } mtx_destroy(&ns->ns_mtx); free(ns, M_NMDM); atomic_subtract_int(&nmdm_count, 1); } static void nmdm_clone(void *arg, struct ucred *cred, char *name, int nameen, struct cdev **dev) { struct nmdmsoftc *ns; struct tty *tp; char *end; int error; char endc; if (*dev != NULL) return; if (strncmp(name, "nmdm", 4) != 0) return; if (strlen(name) <= strlen("nmdmX")) return; /* Device name must be "nmdm%s%c", where %c is 'A' or 'B'. */ end = name + strlen(name) - 1; endc = *end; if (endc != 'A' && endc != 'B') return; ns = malloc(sizeof(*ns), M_NMDM, M_WAITOK | M_ZERO); mtx_init(&ns->ns_mtx, "nmdm", NULL, MTX_DEF); /* Hook the pairs together. */ ns->ns_part1.np_pair = ns; ns->ns_part1.np_other = &ns->ns_part2; TASK_INIT(&ns->ns_part1.np_task, 0, nmdm_task_tty, &ns->ns_part1); callout_init_mtx(&ns->ns_part1.np_callout, &ns->ns_mtx, 0); ns->ns_part2.np_pair = ns; ns->ns_part2.np_other = &ns->ns_part1; TASK_INIT(&ns->ns_part2.np_task, 0, nmdm_task_tty, &ns->ns_part2); callout_init_mtx(&ns->ns_part2.np_callout, &ns->ns_mtx, 0); /* Create device nodes. */ tp = ns->ns_part1.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part1, &ns->ns_mtx); *end = 'A'; error = tty_makedevf(tp, cred, endc == 'A' ? TTYMK_CLONING : 0, "%s", name); if (error) { *end = endc; mtx_destroy(&ns->ns_mtx); free(ns, M_NMDM); return; } tp = ns->ns_part2.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part2, &ns->ns_mtx); *end = 'B'; error = tty_makedevf(tp, cred, endc == 'B' ? TTYMK_CLONING : 0, "%s", name); if (error) { *end = endc; mtx_lock(&ns->ns_mtx); /* see nmdm_free() */ ns->ns_part1.np_other = NULL; atomic_add_int(&nmdm_count, 1); tty_rel_gone(ns->ns_part1.np_tty); return; } if (endc == 'A') *dev = ns->ns_part1.np_tty->t_dev; else *dev = ns->ns_part2.np_tty->t_dev; *end = endc; atomic_add_int(&nmdm_count, 1); } static void nmdm_timeout(void *arg) { struct nmdmpart *np = arg; if (np->np_rate == 0) return; /* * Do a simple Floyd-Steinberg dither here to avoid FP math. * Wipe out unused quota from last tick. */ np->np_accumulator += np->np_credits; np->np_quota = np->np_accumulator >> QS; np->np_accumulator &= ((1 << QS) - 1); taskqueue_enqueue(taskqueue_swi, &np->np_task); callout_reset(&np->np_callout, np->np_rate, nmdm_timeout, np); } static void nmdm_task_tty(void *arg, int pending __unused) { struct tty *tp, *otp; struct nmdmpart *np = arg; char c; tp = np->np_tty; tty_lock(tp); if (tty_gone(tp)) { tty_unlock(tp); return; } otp = np->np_other->np_tty; KASSERT(otp != NULL, ("NULL otp in nmdmstart")); KASSERT(otp != tp, ("NULL otp == tp nmdmstart")); if (np->np_other->np_dcd) { if (!tty_opened(tp)) { np->np_other->np_dcd = 0; ttydisc_modem(otp, 0); } } else { if (tty_opened(tp)) { np->np_other->np_dcd = 1; ttydisc_modem(otp, 1); } } /* This may happen when we are in detach process. */ if (tty_gone(otp)) { tty_unlock(otp); return; } while (ttydisc_rint_poll(otp) > 0) { if (np->np_rate && !np->np_quota) break; if (ttydisc_getc(tp, &c, 1) != 1) break; np->np_quota--; ttydisc_rint(otp, c, 0); } ttydisc_rint_done(otp); tty_unlock(tp); } static int bits_per_char(struct termios *t) { int bits; bits = 1; /* start bit */ switch (t->c_cflag & CSIZE) { case CS5: bits += 5; break; case CS6: bits += 6; break; case CS7: bits += 7; break; case CS8: bits += 8; break; } bits++; /* stop bit */ if (t->c_cflag & PARENB) bits++; if (t->c_cflag & CSTOPB) bits++; return (bits); } static int nmdm_param(struct tty *tp, struct termios *t) { struct nmdmpart *np = tty_softc(tp); struct tty *tp2; int bpc, rate, speed, i; tp2 = np->np_other->np_tty; if (!((t->c_cflag | tp2->t_termios.c_cflag) & CDSR_OFLOW)) { np->np_rate = 0; np->np_other->np_rate = 0; return (0); } /* * DSRFLOW one either side enables rate-simulation for both * directions. * NB: the two directions may run at different rates. */ /* Find the larger of the number of bits transmitted */ bpc = imax(bits_per_char(t), bits_per_char(&tp2->t_termios)); for (i = 0; i < 2; i++) { /* Use the slower of our receive and their transmit rate */ speed = imin(tp2->t_termios.c_ospeed, t->c_ispeed); if (speed == 0) { np->np_rate = 0; np->np_other->np_rate = 0; return (0); } speed <<= QS; /* [bit/sec, scaled] */ speed /= bpc; /* [char/sec, scaled] */ rate = (hz << QS) / speed; /* [hz per callout] */ if (rate == 0) rate = 1; speed *= rate; speed /= hz; /* [(char/sec)/tick, scaled */ np->np_credits = speed; np->np_rate = rate; callout_reset(&np->np_callout, rate, nmdm_timeout, np); /* * swap pointers for second pass so the other end gets * updated as well. */ np = np->np_other; t = &tp2->t_termios; tp2 = tp; } return (0); } static int nmdm_modem(struct tty *tp, int sigon, int sigoff) { struct nmdmpart *np = tty_softc(tp); int i = 0; if (sigon || sigoff) { if (sigon & SER_DTR) np->np_other->np_dcd = 1; if (sigoff & SER_DTR) np->np_other->np_dcd = 0; ttydisc_modem(np->np_other->np_tty, np->np_other->np_dcd); return (0); } else { if (np->np_dcd) i |= SER_DCD; if (np->np_other->np_dcd) i |= SER_DTR; return (i); } } static void nmdm_inwakeup(struct tty *tp) { struct nmdmpart *np = tty_softc(tp); /* We can receive again, so wake up the other side. */ taskqueue_enqueue(taskqueue_swi, &np->np_other->np_task); } static void nmdm_outwakeup(struct tty *tp) { struct nmdmpart *np = tty_softc(tp); /* We can transmit again, so wake up our side. */ taskqueue_enqueue(taskqueue_swi, &np->np_task); } /* * Module handling */ static int nmdm_modevent(module_t mod, int type, void *data) { static eventhandler_tag tag; switch(type) { case MOD_LOAD: tag = EVENTHANDLER_REGISTER(dev_clone, nmdm_clone, 0, 1000); if (tag == NULL) return (ENOMEM); break; case MOD_SHUTDOWN: break; case MOD_UNLOAD: if (nmdm_count != 0) return (EBUSY); EVENTHANDLER_DEREGISTER(dev_clone, tag); break; default: return (EOPNOTSUPP); } return (0); } DEV_MODULE(nmdm, nmdm_modevent, NULL);
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