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31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
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/fcntl.h>
47 #include <sys/kernel.h>
48 #include <sys/limits.h>
49 #include <sys/module.h>
50 #include <sys/serial.h>
51 #include <sys/signalvar.h>
52 #include <sys/malloc.h>
53 #include <sys/taskqueue.h>
55 static MALLOC_DEFINE(M_NMDM, "nullmodem", "nullmodem data structures");
57 static tsw_inwakeup_t nmdm_outwakeup;
58 static tsw_outwakeup_t nmdm_inwakeup;
59 static tsw_param_t nmdm_param;
60 static tsw_modem_t nmdm_modem;
61 static tsw_close_t nmdm_close;
62 static tsw_free_t nmdm_free;
64 static struct ttydevsw nmdm_class = {
65 .tsw_flags = TF_NOPREFIX,
66 .tsw_inwakeup = nmdm_inwakeup,
67 .tsw_outwakeup = nmdm_outwakeup,
68 .tsw_param = nmdm_param,
69 .tsw_modem = nmdm_modem,
70 .tsw_close = nmdm_close,
71 .tsw_free = nmdm_free,
74 static void nmdm_task_tty(void *, int);
82 struct nmdmpart *np_other;
83 struct nmdmsoftc *np_pair;
84 struct callout np_callout;
86 u_long np_accumulator;
90 #define QS 8 /* Quota shift */
94 struct nmdmpart ns_part1;
95 struct nmdmpart ns_part2;
99 static int nmdm_count = 0;
102 nmdm_close(struct tty *tp)
105 struct nmdmpart *onp;
112 /* If second part is opened, do not destroy ourselves. */
116 /* Shut down self. */
119 /* Shut down second part. */
130 nmdm_free(void *softc)
132 struct nmdmpart *np = (struct nmdmpart *)softc;
133 struct nmdmsoftc *ns = np->np_pair;
135 callout_drain(&np->np_callout);
136 taskqueue_drain(taskqueue_swi, &np->np_task);
139 * The function is called on both parts simultaneously. We serialize
140 * with help of ns_mtx. The first invocation should return and
141 * delegate freeing of resources to the second.
143 mtx_lock(&ns->ns_mtx);
144 if (np->np_other != NULL) {
145 np->np_other->np_other = NULL;
146 mtx_unlock(&ns->ns_mtx);
149 mtx_destroy(&ns->ns_mtx);
151 atomic_subtract_int(&nmdm_count, 1);
155 nmdm_clone(void *arg, struct ucred *cred, char *name, int nameen,
158 struct nmdmsoftc *ns;
166 if (strncmp(name, "nmdm", 4) != 0)
168 if (strlen(name) <= strlen("nmdmX"))
171 /* Device name must be "nmdm%s%c", where %c is 'A' or 'B'. */
172 end = name + strlen(name) - 1;
174 if (endc != 'A' && endc != 'B')
177 ns = malloc(sizeof(*ns), M_NMDM, M_WAITOK | M_ZERO);
178 mtx_init(&ns->ns_mtx, "nmdm", NULL, MTX_DEF);
180 /* Hook the pairs together. */
181 ns->ns_part1.np_pair = ns;
182 ns->ns_part1.np_other = &ns->ns_part2;
183 TASK_INIT(&ns->ns_part1.np_task, 0, nmdm_task_tty, &ns->ns_part1);
184 callout_init_mtx(&ns->ns_part1.np_callout, &ns->ns_mtx, 0);
186 ns->ns_part2.np_pair = ns;
187 ns->ns_part2.np_other = &ns->ns_part1;
188 TASK_INIT(&ns->ns_part2.np_task, 0, nmdm_task_tty, &ns->ns_part2);
189 callout_init_mtx(&ns->ns_part2.np_callout, &ns->ns_mtx, 0);
191 /* Create device nodes. */
192 tp = ns->ns_part1.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part1,
195 error = tty_makedevf(tp, NULL, endc == 'A' ? TTYMK_CLONING : 0,
199 mtx_destroy(&ns->ns_mtx);
204 tp = ns->ns_part2.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part2,
207 error = tty_makedevf(tp, NULL, endc == 'B' ? TTYMK_CLONING : 0,
211 mtx_lock(&ns->ns_mtx);
212 /* see nmdm_free() */
213 ns->ns_part1.np_other = NULL;
214 atomic_add_int(&nmdm_count, 1);
215 tty_rel_gone(ns->ns_part1.np_tty);
220 *dev = ns->ns_part1.np_tty->t_dev;
222 *dev = ns->ns_part2.np_tty->t_dev;
225 atomic_add_int(&nmdm_count, 1);
229 nmdm_timeout(void *arg)
231 struct nmdmpart *np = arg;
233 if (np->np_rate == 0)
237 * Do a simple Floyd-Steinberg dither here to avoid FP math.
238 * Wipe out unused quota from last tick.
240 np->np_accumulator += np->np_credits;
241 np->np_quota = np->np_accumulator >> QS;
242 np->np_accumulator &= ((1 << QS) - 1);
244 taskqueue_enqueue(taskqueue_swi, &np->np_task);
245 callout_reset(&np->np_callout, np->np_rate, nmdm_timeout, np);
249 nmdm_task_tty(void *arg, int pending __unused)
251 struct tty *tp, *otp;
252 struct nmdmpart *np = arg;
262 otp = np->np_other->np_tty;
263 KASSERT(otp != NULL, ("NULL otp in nmdmstart"));
264 KASSERT(otp != tp, ("NULL otp == tp nmdmstart"));
265 if (np->np_other->np_dcd) {
266 if (!tty_opened(tp)) {
267 np->np_other->np_dcd = 0;
268 ttydisc_modem(otp, 0);
271 if (tty_opened(tp)) {
272 np->np_other->np_dcd = 1;
273 ttydisc_modem(otp, 1);
277 /* This may happen when we are in detach process. */
283 while (ttydisc_rint_poll(otp) > 0) {
284 if (np->np_rate && !np->np_quota)
286 if (ttydisc_getc(tp, &c, 1) != 1)
289 ttydisc_rint(otp, c, 0);
292 ttydisc_rint_done(otp);
298 bits_per_char(struct termios *t)
302 bits = 1; /* start bit */
303 switch (t->c_cflag & CSIZE) {
304 case CS5: bits += 5; break;
305 case CS6: bits += 6; break;
306 case CS7: bits += 7; break;
307 case CS8: bits += 8; break;
309 bits++; /* stop bit */
310 if (t->c_cflag & PARENB)
312 if (t->c_cflag & CSTOPB)
318 nmdm_param(struct tty *tp, struct termios *t)
320 struct nmdmpart *np = tty_softc(tp);
322 int bpc, rate, speed, i;
324 tp2 = np->np_other->np_tty;
326 if (!((t->c_cflag | tp2->t_termios.c_cflag) & CDSR_OFLOW)) {
328 np->np_other->np_rate = 0;
333 * DSRFLOW one either side enables rate-simulation for both
335 * NB: the two directions may run at different rates.
338 /* Find the larger of the number of bits transmitted */
339 bpc = imax(bits_per_char(t), bits_per_char(&tp2->t_termios));
341 for (i = 0; i < 2; i++) {
342 /* Use the slower of our receive and their transmit rate */
343 speed = imin(tp2->t_termios.c_ospeed, t->c_ispeed);
346 np->np_other->np_rate = 0;
350 speed <<= QS; /* [bit/sec, scaled] */
351 speed /= bpc; /* [char/sec, scaled] */
352 rate = (hz << QS) / speed; /* [hz per callout] */
357 speed /= hz; /* [(char/sec)/tick, scaled */
359 np->np_credits = speed;
361 callout_reset(&np->np_callout, rate, nmdm_timeout, np);
364 * swap pointers for second pass so the other end gets
376 nmdm_modem(struct tty *tp, int sigon, int sigoff)
378 struct nmdmpart *np = tty_softc(tp);
381 if (sigon || sigoff) {
383 np->np_other->np_dcd = 1;
384 if (sigoff & SER_DTR)
385 np->np_other->np_dcd = 0;
387 ttydisc_modem(np->np_other->np_tty, np->np_other->np_dcd);
393 if (np->np_other->np_dcd)
401 nmdm_inwakeup(struct tty *tp)
403 struct nmdmpart *np = tty_softc(tp);
405 /* We can receive again, so wake up the other side. */
406 taskqueue_enqueue(taskqueue_swi, &np->np_other->np_task);
410 nmdm_outwakeup(struct tty *tp)
412 struct nmdmpart *np = tty_softc(tp);
414 /* We can transmit again, so wake up our side. */
415 taskqueue_enqueue(taskqueue_swi, &np->np_task);
422 nmdm_modevent(module_t mod, int type, void *data)
424 static eventhandler_tag tag;
428 tag = EVENTHANDLER_REGISTER(dev_clone, nmdm_clone, 0, 1000);
439 EVENTHANDLER_DEREGISTER(dev_clone, tag);
449 DEV_MODULE(nmdm, nmdm_modevent, NULL);