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33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
37 * Pseudo-nulmodem driver
38 * Mighty handy for use with serial console in Vmware
41 #include <sys/param.h>
42 #include <sys/systm.h>
47 #include <sys/fcntl.h>
49 #include <sys/kernel.h>
50 #include <sys/limits.h>
51 #include <sys/module.h>
52 #include <sys/serial.h>
53 #include <sys/signalvar.h>
54 #include <sys/malloc.h>
55 #include <sys/taskqueue.h>
57 static MALLOC_DEFINE(M_NMDM, "nullmodem", "nullmodem data structures");
59 static tsw_inwakeup_t nmdm_outwakeup;
60 static tsw_outwakeup_t nmdm_inwakeup;
61 static tsw_param_t nmdm_param;
62 static tsw_modem_t nmdm_modem;
63 static tsw_close_t nmdm_close;
64 static tsw_free_t nmdm_free;
66 static struct ttydevsw nmdm_class = {
67 .tsw_flags = TF_NOPREFIX,
68 .tsw_inwakeup = nmdm_inwakeup,
69 .tsw_outwakeup = nmdm_outwakeup,
70 .tsw_param = nmdm_param,
71 .tsw_modem = nmdm_modem,
72 .tsw_close = nmdm_close,
73 .tsw_free = nmdm_free,
76 static void nmdm_task_tty(void *, int);
84 struct nmdmpart *np_other;
85 struct nmdmsoftc *np_pair;
86 struct callout np_callout;
88 u_long np_accumulator;
92 #define QS 8 /* Quota shift */
96 struct nmdmpart ns_part1;
97 struct nmdmpart ns_part2;
101 static int nmdm_count = 0;
104 nmdm_close(struct tty *tp)
107 struct nmdmpart *onp;
114 /* If second part is opened, do not destroy ourselves. */
118 /* Shut down self. */
121 /* Shut down second part. */
132 nmdm_free(void *softc)
134 struct nmdmpart *np = (struct nmdmpart *)softc;
135 struct nmdmsoftc *ns = np->np_pair;
137 callout_drain(&np->np_callout);
138 taskqueue_drain(taskqueue_swi, &np->np_task);
141 * The function is called on both parts simultaneously. We serialize
142 * with help of ns_mtx. The first invocation should return and
143 * delegate freeing of resources to the second.
145 mtx_lock(&ns->ns_mtx);
146 if (np->np_other != NULL) {
147 np->np_other->np_other = NULL;
148 mtx_unlock(&ns->ns_mtx);
151 mtx_destroy(&ns->ns_mtx);
153 atomic_subtract_int(&nmdm_count, 1);
157 nmdm_clone(void *arg, struct ucred *cred, char *name, int nameen,
160 struct nmdmsoftc *ns;
168 if (strncmp(name, "nmdm", 4) != 0)
170 if (strlen(name) <= strlen("nmdmX"))
173 /* Device name must be "nmdm%s%c", where %c is 'A' or 'B'. */
174 end = name + strlen(name) - 1;
176 if (endc != 'A' && endc != 'B')
179 ns = malloc(sizeof(*ns), M_NMDM, M_WAITOK | M_ZERO);
180 mtx_init(&ns->ns_mtx, "nmdm", NULL, MTX_DEF);
182 /* Hook the pairs together. */
183 ns->ns_part1.np_pair = ns;
184 ns->ns_part1.np_other = &ns->ns_part2;
185 TASK_INIT(&ns->ns_part1.np_task, 0, nmdm_task_tty, &ns->ns_part1);
186 callout_init_mtx(&ns->ns_part1.np_callout, &ns->ns_mtx, 0);
188 ns->ns_part2.np_pair = ns;
189 ns->ns_part2.np_other = &ns->ns_part1;
190 TASK_INIT(&ns->ns_part2.np_task, 0, nmdm_task_tty, &ns->ns_part2);
191 callout_init_mtx(&ns->ns_part2.np_callout, &ns->ns_mtx, 0);
193 /* Create device nodes. */
194 tp = ns->ns_part1.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part1,
197 error = tty_makedevf(tp, NULL, endc == 'A' ? TTYMK_CLONING : 0,
201 mtx_destroy(&ns->ns_mtx);
206 tp = ns->ns_part2.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part2,
209 error = tty_makedevf(tp, NULL, endc == 'B' ? TTYMK_CLONING : 0,
213 mtx_lock(&ns->ns_mtx);
214 /* see nmdm_free() */
215 ns->ns_part1.np_other = NULL;
216 atomic_add_int(&nmdm_count, 1);
217 tty_rel_gone(ns->ns_part1.np_tty);
222 *dev = ns->ns_part1.np_tty->t_dev;
224 *dev = ns->ns_part2.np_tty->t_dev;
227 atomic_add_int(&nmdm_count, 1);
231 nmdm_timeout(void *arg)
233 struct nmdmpart *np = arg;
235 if (np->np_rate == 0)
239 * Do a simple Floyd-Steinberg dither here to avoid FP math.
240 * Wipe out unused quota from last tick.
242 np->np_accumulator += np->np_credits;
243 np->np_quota = np->np_accumulator >> QS;
244 np->np_accumulator &= ((1 << QS) - 1);
246 taskqueue_enqueue(taskqueue_swi, &np->np_task);
247 callout_reset(&np->np_callout, np->np_rate, nmdm_timeout, np);
251 nmdm_task_tty(void *arg, int pending __unused)
253 struct tty *tp, *otp;
254 struct nmdmpart *np = arg;
264 otp = np->np_other->np_tty;
265 KASSERT(otp != NULL, ("NULL otp in nmdmstart"));
266 KASSERT(otp != tp, ("NULL otp == tp nmdmstart"));
267 if (np->np_other->np_dcd) {
268 if (!tty_opened(tp)) {
269 np->np_other->np_dcd = 0;
270 ttydisc_modem(otp, 0);
273 if (tty_opened(tp)) {
274 np->np_other->np_dcd = 1;
275 ttydisc_modem(otp, 1);
279 /* This may happen when we are in detach process. */
285 while (ttydisc_rint_poll(otp) > 0) {
286 if (np->np_rate && !np->np_quota)
288 if (ttydisc_getc(tp, &c, 1) != 1)
291 ttydisc_rint(otp, c, 0);
294 ttydisc_rint_done(otp);
300 bits_per_char(struct termios *t)
304 bits = 1; /* start bit */
305 switch (t->c_cflag & CSIZE) {
306 case CS5: bits += 5; break;
307 case CS6: bits += 6; break;
308 case CS7: bits += 7; break;
309 case CS8: bits += 8; break;
311 bits++; /* stop bit */
312 if (t->c_cflag & PARENB)
314 if (t->c_cflag & CSTOPB)
320 nmdm_param(struct tty *tp, struct termios *t)
322 struct nmdmpart *np = tty_softc(tp);
324 int bpc, rate, speed, i;
326 tp2 = np->np_other->np_tty;
328 if (!((t->c_cflag | tp2->t_termios.c_cflag) & CDSR_OFLOW)) {
330 np->np_other->np_rate = 0;
335 * DSRFLOW one either side enables rate-simulation for both
337 * NB: the two directions may run at different rates.
340 /* Find the larger of the number of bits transmitted */
341 bpc = imax(bits_per_char(t), bits_per_char(&tp2->t_termios));
343 for (i = 0; i < 2; i++) {
344 /* Use the slower of our receive and their transmit rate */
345 speed = imin(tp2->t_termios.c_ospeed, t->c_ispeed);
348 np->np_other->np_rate = 0;
352 speed <<= QS; /* [bit/sec, scaled] */
353 speed /= bpc; /* [char/sec, scaled] */
354 rate = (hz << QS) / speed; /* [hz per callout] */
359 speed /= hz; /* [(char/sec)/tick, scaled */
361 np->np_credits = speed;
363 callout_reset(&np->np_callout, rate, nmdm_timeout, np);
366 * swap pointers for second pass so the other end gets
378 nmdm_modem(struct tty *tp, int sigon, int sigoff)
380 struct nmdmpart *np = tty_softc(tp);
383 if (sigon || sigoff) {
385 np->np_other->np_dcd = 1;
386 if (sigoff & SER_DTR)
387 np->np_other->np_dcd = 0;
389 ttydisc_modem(np->np_other->np_tty, np->np_other->np_dcd);
395 if (np->np_other->np_dcd)
403 nmdm_inwakeup(struct tty *tp)
405 struct nmdmpart *np = tty_softc(tp);
407 /* We can receive again, so wake up the other side. */
408 taskqueue_enqueue(taskqueue_swi, &np->np_other->np_task);
412 nmdm_outwakeup(struct tty *tp)
414 struct nmdmpart *np = tty_softc(tp);
416 /* We can transmit again, so wake up our side. */
417 taskqueue_enqueue(taskqueue_swi, &np->np_task);
424 nmdm_modevent(module_t mod, int type, void *data)
426 static eventhandler_tag tag;
430 tag = EVENTHANDLER_REGISTER(dev_clone, nmdm_clone, 0, 1000);
441 EVENTHANDLER_DEREGISTER(dev_clone, tag);
451 DEV_MODULE(nmdm, nmdm_modevent, NULL);