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33 #include <sys/cdefs.h>
35 * Pseudo-nulmodem driver
36 * Mighty handy for use with serial console in Vmware
39 #include <sys/param.h>
40 #include <sys/systm.h>
45 #include <sys/eventhandler.h>
46 #include <sys/fcntl.h>
48 #include <sys/kernel.h>
49 #include <sys/limits.h>
50 #include <sys/module.h>
51 #include <sys/serial.h>
52 #include <sys/signalvar.h>
53 #include <sys/malloc.h>
54 #include <sys/taskqueue.h>
56 static MALLOC_DEFINE(M_NMDM, "nullmodem", "nullmodem data structures");
58 static tsw_inwakeup_t nmdm_outwakeup;
59 static tsw_outwakeup_t nmdm_inwakeup;
60 static tsw_param_t nmdm_param;
61 static tsw_modem_t nmdm_modem;
62 static tsw_close_t nmdm_close;
63 static tsw_free_t nmdm_free;
65 static struct ttydevsw nmdm_class = {
66 .tsw_flags = TF_NOPREFIX,
67 .tsw_inwakeup = nmdm_inwakeup,
68 .tsw_outwakeup = nmdm_outwakeup,
69 .tsw_param = nmdm_param,
70 .tsw_modem = nmdm_modem,
71 .tsw_close = nmdm_close,
72 .tsw_free = nmdm_free,
75 static void nmdm_task_tty(void *, int);
83 struct nmdmpart *np_other;
84 struct nmdmsoftc *np_pair;
85 struct callout np_callout;
87 u_long np_accumulator;
91 #define QS 8 /* Quota shift */
95 struct nmdmpart ns_part1;
96 struct nmdmpart ns_part2;
100 static int nmdm_count = 0;
103 nmdm_close(struct tty *tp)
106 struct nmdmpart *onp;
113 /* If second part is opened, do not destroy ourselves. */
117 /* Shut down self. */
120 /* Shut down second part. */
131 nmdm_free(void *softc)
133 struct nmdmpart *np = (struct nmdmpart *)softc;
134 struct nmdmsoftc *ns = np->np_pair;
136 callout_drain(&np->np_callout);
137 taskqueue_drain(taskqueue_swi, &np->np_task);
140 * The function is called on both parts simultaneously. We serialize
141 * with help of ns_mtx. The first invocation should return and
142 * delegate freeing of resources to the second.
144 mtx_lock(&ns->ns_mtx);
145 if (np->np_other != NULL) {
146 np->np_other->np_other = NULL;
147 mtx_unlock(&ns->ns_mtx);
150 mtx_destroy(&ns->ns_mtx);
152 atomic_subtract_int(&nmdm_count, 1);
156 nmdm_clone(void *arg, struct ucred *cred, char *name, int nameen,
159 struct nmdmsoftc *ns;
167 if (strncmp(name, "nmdm", 4) != 0)
169 if (strlen(name) <= strlen("nmdmX"))
172 /* Device name must be "nmdm%s%c", where %c is 'A' or 'B'. */
173 end = name + strlen(name) - 1;
175 if (endc != 'A' && endc != 'B')
178 ns = malloc(sizeof(*ns), M_NMDM, M_WAITOK | M_ZERO);
179 mtx_init(&ns->ns_mtx, "nmdm", NULL, MTX_DEF);
181 /* Hook the pairs together. */
182 ns->ns_part1.np_pair = ns;
183 ns->ns_part1.np_other = &ns->ns_part2;
184 TASK_INIT(&ns->ns_part1.np_task, 0, nmdm_task_tty, &ns->ns_part1);
185 callout_init_mtx(&ns->ns_part1.np_callout, &ns->ns_mtx, 0);
187 ns->ns_part2.np_pair = ns;
188 ns->ns_part2.np_other = &ns->ns_part1;
189 TASK_INIT(&ns->ns_part2.np_task, 0, nmdm_task_tty, &ns->ns_part2);
190 callout_init_mtx(&ns->ns_part2.np_callout, &ns->ns_mtx, 0);
192 /* Create device nodes. */
193 tp = ns->ns_part1.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part1,
196 error = tty_makedevf(tp, cred, endc == 'A' ? TTYMK_CLONING : 0,
200 mtx_destroy(&ns->ns_mtx);
205 tp = ns->ns_part2.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part2,
208 error = tty_makedevf(tp, cred, endc == 'B' ? TTYMK_CLONING : 0,
212 mtx_lock(&ns->ns_mtx);
213 /* see nmdm_free() */
214 ns->ns_part1.np_other = NULL;
215 atomic_add_int(&nmdm_count, 1);
216 tty_rel_gone(ns->ns_part1.np_tty);
221 *dev = ns->ns_part1.np_tty->t_dev;
223 *dev = ns->ns_part2.np_tty->t_dev;
226 atomic_add_int(&nmdm_count, 1);
230 nmdm_timeout(void *arg)
232 struct nmdmpart *np = arg;
234 if (np->np_rate == 0)
238 * Do a simple Floyd-Steinberg dither here to avoid FP math.
239 * Wipe out unused quota from last tick.
241 np->np_accumulator += np->np_credits;
242 np->np_quota = np->np_accumulator >> QS;
243 np->np_accumulator &= ((1 << QS) - 1);
245 taskqueue_enqueue(taskqueue_swi, &np->np_task);
246 callout_reset(&np->np_callout, np->np_rate, nmdm_timeout, np);
250 nmdm_task_tty(void *arg, int pending __unused)
252 struct tty *tp, *otp;
253 struct nmdmpart *np = arg;
263 otp = np->np_other->np_tty;
264 KASSERT(otp != NULL, ("NULL otp in nmdmstart"));
265 KASSERT(otp != tp, ("NULL otp == tp nmdmstart"));
266 if (np->np_other->np_dcd) {
267 if (!tty_opened(tp)) {
268 np->np_other->np_dcd = 0;
269 ttydisc_modem(otp, 0);
272 if (tty_opened(tp)) {
273 np->np_other->np_dcd = 1;
274 ttydisc_modem(otp, 1);
278 /* This may happen when we are in detach process. */
284 while (ttydisc_rint_poll(otp) > 0) {
285 if (np->np_rate && !np->np_quota)
287 if (ttydisc_getc(tp, &c, 1) != 1)
290 ttydisc_rint(otp, c, 0);
293 ttydisc_rint_done(otp);
299 bits_per_char(struct termios *t)
303 bits = 1; /* start bit */
304 switch (t->c_cflag & CSIZE) {
305 case CS5: bits += 5; break;
306 case CS6: bits += 6; break;
307 case CS7: bits += 7; break;
308 case CS8: bits += 8; break;
310 bits++; /* stop bit */
311 if (t->c_cflag & PARENB)
313 if (t->c_cflag & CSTOPB)
319 nmdm_param(struct tty *tp, struct termios *t)
321 struct nmdmpart *np = tty_softc(tp);
323 int bpc, rate, speed, i;
325 tp2 = np->np_other->np_tty;
327 if (!((t->c_cflag | tp2->t_termios.c_cflag) & CDSR_OFLOW)) {
329 np->np_other->np_rate = 0;
334 * DSRFLOW one either side enables rate-simulation for both
336 * NB: the two directions may run at different rates.
339 /* Find the larger of the number of bits transmitted */
340 bpc = imax(bits_per_char(t), bits_per_char(&tp2->t_termios));
342 for (i = 0; i < 2; i++) {
343 /* Use the slower of our receive and their transmit rate */
344 speed = imin(tp2->t_termios.c_ospeed, t->c_ispeed);
347 np->np_other->np_rate = 0;
351 speed <<= QS; /* [bit/sec, scaled] */
352 speed /= bpc; /* [char/sec, scaled] */
353 rate = (hz << QS) / speed; /* [hz per callout] */
358 speed /= hz; /* [(char/sec)/tick, scaled */
360 np->np_credits = speed;
362 callout_reset(&np->np_callout, rate, nmdm_timeout, np);
365 * swap pointers for second pass so the other end gets
377 nmdm_modem(struct tty *tp, int sigon, int sigoff)
379 struct nmdmpart *np = tty_softc(tp);
382 if (sigon || sigoff) {
384 np->np_other->np_dcd = 1;
385 if (sigoff & SER_DTR)
386 np->np_other->np_dcd = 0;
388 ttydisc_modem(np->np_other->np_tty, np->np_other->np_dcd);
394 if (np->np_other->np_dcd)
402 nmdm_inwakeup(struct tty *tp)
404 struct nmdmpart *np = tty_softc(tp);
406 /* We can receive again, so wake up the other side. */
407 taskqueue_enqueue(taskqueue_swi, &np->np_other->np_task);
411 nmdm_outwakeup(struct tty *tp)
413 struct nmdmpart *np = tty_softc(tp);
415 /* We can transmit again, so wake up our side. */
416 taskqueue_enqueue(taskqueue_swi, &np->np_task);
423 nmdm_modevent(module_t mod, int type, void *data)
425 static eventhandler_tag tag;
429 tag = EVENTHANDLER_REGISTER(dev_clone, nmdm_clone, 0, 1000);
440 EVENTHANDLER_DEREGISTER(dev_clone, tag);
450 DEV_MODULE(nmdm, nmdm_modevent, NULL);