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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * u_serial.c - utilities for USB gadget "serial port"/TTY support
4 *
5 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
6 * Copyright (C) 2008 David Brownell
7 * Copyright (C) 2008 by Nokia Corporation
8 *
9 * This code also borrows from usbserial.c, which is
10 * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
11 * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
12 * Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
13 */
14
15/* #define VERBOSE_DEBUG */
16
17#include <linux/kernel.h>
18#include <linux/sched.h>
19#include <linux/device.h>
20#include <linux/delay.h>
21#include <linux/tty.h>
22#include <linux/tty_flip.h>
23#include <linux/slab.h>
24#include <linux/export.h>
25#include <linux/module.h>
26#include <linux/console.h>
27#include <linux/kstrtox.h>
28#include <linux/kthread.h>
29#include <linux/workqueue.h>
30#include <linux/kfifo.h>
31#include <linux/serial.h>
32
33#include "u_serial.h"
34
35
36/*
37 * This component encapsulates the TTY layer glue needed to provide basic
38 * "serial port" functionality through the USB gadget stack. Each such
39 * port is exposed through a /dev/ttyGS* node.
40 *
41 * After this module has been loaded, the individual TTY port can be requested
42 * (gserial_alloc_line()) and it will stay available until they are removed
43 * (gserial_free_line()). Each one may be connected to a USB function
44 * (gserial_connect), or disconnected (with gserial_disconnect) when the USB
45 * host issues a config change event. Data can only flow when the port is
46 * connected to the host.
47 *
48 * A given TTY port can be made available in multiple configurations.
49 * For example, each one might expose a ttyGS0 node which provides a
50 * login application. In one case that might use CDC ACM interface 0,
51 * while another configuration might use interface 3 for that. The
52 * work to handle that (including descriptor management) is not part
53 * of this component.
54 *
55 * Configurations may expose more than one TTY port. For example, if
56 * ttyGS0 provides login service, then ttyGS1 might provide dialer access
57 * for a telephone or fax link. And ttyGS2 might be something that just
58 * needs a simple byte stream interface for some messaging protocol that
59 * is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
60 *
61 *
62 * gserial is the lifecycle interface, used by USB functions
63 * gs_port is the I/O nexus, used by the tty driver
64 * tty_struct links to the tty/filesystem framework
65 *
66 * gserial <---> gs_port ... links will be null when the USB link is
67 * inactive; managed by gserial_{connect,disconnect}(). each gserial
68 * instance can wrap its own USB control protocol.
69 * gserial->ioport == usb_ep->driver_data ... gs_port
70 * gs_port->port_usb ... gserial
71 *
72 * gs_port <---> tty_struct ... links will be null when the TTY file
73 * isn't opened; managed by gs_open()/gs_close()
74 * gserial->port_tty ... tty_struct
75 * tty_struct->driver_data ... gserial
76 */
77
78/* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
79 * next layer of buffering. For TX that's a circular buffer; for RX
80 * consider it a NOP. A third layer is provided by the TTY code.
81 */
82#define QUEUE_SIZE 16
83#define WRITE_BUF_SIZE 8192 /* TX only */
84#define GS_CONSOLE_BUF_SIZE 8192
85
86/* Prevents race conditions while accessing gser->ioport */
87static DEFINE_SPINLOCK(serial_port_lock);
88
89/* console info */
90struct gs_console {
91 struct console console;
92 struct work_struct work;
93 spinlock_t lock;
94 struct usb_request *req;
95 struct kfifo buf;
96 size_t missed;
97};
98
99/*
100 * The port structure holds info for each port, one for each minor number
101 * (and thus for each /dev/ node).
102 */
103struct gs_port {
104 struct tty_port port;
105 spinlock_t port_lock; /* guard port_* access */
106
107 struct gserial *port_usb;
108#ifdef CONFIG_U_SERIAL_CONSOLE
109 struct gs_console *console;
110#endif
111
112 u8 port_num;
113
114 struct list_head read_pool;
115 int read_started;
116 int read_allocated;
117 struct list_head read_queue;
118 unsigned n_read;
119 struct delayed_work push;
120
121 struct list_head write_pool;
122 int write_started;
123 int write_allocated;
124 struct kfifo port_write_buf;
125 wait_queue_head_t drain_wait; /* wait while writes drain */
126 bool write_busy;
127 wait_queue_head_t close_wait;
128 bool suspended; /* port suspended */
129 bool start_delayed; /* delay start when suspended */
130 struct async_icount icount;
131
132 /* REVISIT this state ... */
133 struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
134};
135
136static struct portmaster {
137 struct mutex lock; /* protect open/close */
138 struct gs_port *port;
139} ports[MAX_U_SERIAL_PORTS];
140
141#define GS_CLOSE_TIMEOUT 15 /* seconds */
142
143
144
145#ifdef VERBOSE_DEBUG
146#ifndef pr_vdebug
147#define pr_vdebug(fmt, arg...) \
148 pr_debug(fmt, ##arg)
149#endif /* pr_vdebug */
150#else
151#ifndef pr_vdebug
152#define pr_vdebug(fmt, arg...) \
153 ({ if (0) pr_debug(fmt, ##arg); })
154#endif /* pr_vdebug */
155#endif
156
157/*-------------------------------------------------------------------------*/
158
159/* I/O glue between TTY (upper) and USB function (lower) driver layers */
160
161/*
162 * gs_alloc_req
163 *
164 * Allocate a usb_request and its buffer. Returns a pointer to the
165 * usb_request or NULL if there is an error.
166 */
167struct usb_request *
168gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
169{
170 struct usb_request *req;
171
172 req = usb_ep_alloc_request(ep, kmalloc_flags);
173
174 if (req != NULL) {
175 req->length = len;
176 req->buf = kmalloc(len, kmalloc_flags);
177 if (req->buf == NULL) {
178 usb_ep_free_request(ep, req);
179 return NULL;
180 }
181 }
182
183 return req;
184}
185EXPORT_SYMBOL_GPL(gs_alloc_req);
186
187/*
188 * gs_free_req
189 *
190 * Free a usb_request and its buffer.
191 */
192void gs_free_req(struct usb_ep *ep, struct usb_request *req)
193{
194 kfree(req->buf);
195 usb_ep_free_request(ep, req);
196}
197EXPORT_SYMBOL_GPL(gs_free_req);
198
199/*
200 * gs_send_packet
201 *
202 * If there is data to send, a packet is built in the given
203 * buffer and the size is returned. If there is no data to
204 * send, 0 is returned.
205 *
206 * Called with port_lock held.
207 */
208static unsigned
209gs_send_packet(struct gs_port *port, char *packet, unsigned size)
210{
211 unsigned len;
212
213 len = kfifo_len(&port->port_write_buf);
214 if (len < size)
215 size = len;
216 if (size != 0)
217 size = kfifo_out(&port->port_write_buf, packet, size);
218 return size;
219}
220
221/*
222 * gs_start_tx
223 *
224 * This function finds available write requests, calls
225 * gs_send_packet to fill these packets with data, and
226 * continues until either there are no more write requests
227 * available or no more data to send. This function is
228 * run whenever data arrives or write requests are available.
229 *
230 * Context: caller owns port_lock; port_usb is non-null.
231 */
232static int gs_start_tx(struct gs_port *port)
233/*
234__releases(&port->port_lock)
235__acquires(&port->port_lock)
236*/
237{
238 struct list_head *pool = &port->write_pool;
239 struct usb_ep *in;
240 int status = 0;
241 bool do_tty_wake = false;
242
243 if (!port->port_usb)
244 return status;
245
246 in = port->port_usb->in;
247
248 while (!port->write_busy && !list_empty(pool)) {
249 struct usb_request *req;
250 int len;
251
252 if (port->write_started >= QUEUE_SIZE)
253 break;
254
255 req = list_entry(pool->next, struct usb_request, list);
256 len = gs_send_packet(port, req->buf, in->maxpacket);
257 if (len == 0) {
258 wake_up_interruptible(&port->drain_wait);
259 break;
260 }
261 do_tty_wake = true;
262 port->icount.tx += len;
263
264 req->length = len;
265 list_del(&req->list);
266 req->zero = kfifo_is_empty(&port->port_write_buf);
267
268 pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);
269
270 /* Drop lock while we call out of driver; completions
271 * could be issued while we do so. Disconnection may
272 * happen too; maybe immediately before we queue this!
273 *
274 * NOTE that we may keep sending data for a while after
275 * the TTY closed (dev->ioport->port_tty is NULL).
276 */
277 port->write_busy = true;
278 spin_unlock(&port->port_lock);
279 status = usb_ep_queue(in, req, GFP_ATOMIC);
280 spin_lock(&port->port_lock);
281 port->write_busy = false;
282
283 if (status) {
284 pr_debug("%s: %s %s err %d\n",
285 __func__, "queue", in->name, status);
286 list_add(&req->list, pool);
287 break;
288 }
289
290 port->write_started++;
291
292 /* abort immediately after disconnect */
293 if (!port->port_usb)
294 break;
295 }
296
297 if (do_tty_wake && port->port.tty)
298 tty_wakeup(port->port.tty);
299 return status;
300}
301
302/*
303 * Context: caller owns port_lock, and port_usb is set
304 */
305static unsigned gs_start_rx(struct gs_port *port)
306/*
307__releases(&port->port_lock)
308__acquires(&port->port_lock)
309*/
310{
311 struct list_head *pool = &port->read_pool;
312 struct usb_ep *out = port->port_usb->out;
313
314 while (!list_empty(pool)) {
315 struct usb_request *req;
316 int status;
317 struct tty_struct *tty;
318
319 /* no more rx if closed */
320 tty = port->port.tty;
321 if (!tty)
322 break;
323
324 if (port->read_started >= QUEUE_SIZE)
325 break;
326
327 req = list_entry(pool->next, struct usb_request, list);
328 list_del(&req->list);
329 req->length = out->maxpacket;
330
331 /* drop lock while we call out; the controller driver
332 * may need to call us back (e.g. for disconnect)
333 */
334 spin_unlock(&port->port_lock);
335 status = usb_ep_queue(out, req, GFP_ATOMIC);
336 spin_lock(&port->port_lock);
337
338 if (status) {
339 pr_debug("%s: %s %s err %d\n",
340 __func__, "queue", out->name, status);
341 list_add(&req->list, pool);
342 break;
343 }
344 port->read_started++;
345
346 /* abort immediately after disconnect */
347 if (!port->port_usb)
348 break;
349 }
350 return port->read_started;
351}
352
353/*
354 * RX work takes data out of the RX queue and hands it up to the TTY
355 * layer until it refuses to take any more data (or is throttled back).
356 * Then it issues reads for any further data.
357 *
358 * If the RX queue becomes full enough that no usb_request is queued,
359 * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
360 * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
361 * can be buffered before the TTY layer's buffers (currently 64 KB).
362 */
363static void gs_rx_push(struct work_struct *work)
364{
365 struct delayed_work *w = to_delayed_work(work);
366 struct gs_port *port = container_of(w, struct gs_port, push);
367 struct tty_struct *tty;
368 struct list_head *queue = &port->read_queue;
369 bool disconnect = false;
370 bool do_push = false;
371
372 /* hand any queued data to the tty */
373 spin_lock_irq(&port->port_lock);
374 tty = port->port.tty;
375 while (!list_empty(queue)) {
376 struct usb_request *req;
377
378 req = list_first_entry(queue, struct usb_request, list);
379
380 /* leave data queued if tty was rx throttled */
381 if (tty && tty_throttled(tty))
382 break;
383
384 switch (req->status) {
385 case -ESHUTDOWN:
386 disconnect = true;
387 pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
388 break;
389
390 default:
391 /* presumably a transient fault */
392 pr_warn("ttyGS%d: unexpected RX status %d\n",
393 port->port_num, req->status);
394 fallthrough;
395 case 0:
396 /* normal completion */
397 break;
398 }
399
400 /* push data to (open) tty */
401 if (req->actual && tty) {
402 char *packet = req->buf;
403 unsigned size = req->actual;
404 unsigned n;
405 int count;
406
407 /* we may have pushed part of this packet already... */
408 n = port->n_read;
409 if (n) {
410 packet += n;
411 size -= n;
412 }
413
414 port->icount.rx += size;
415 count = tty_insert_flip_string(&port->port, packet,
416 size);
417 if (count)
418 do_push = true;
419 if (count != size) {
420 /* stop pushing; TTY layer can't handle more */
421 port->n_read += count;
422 pr_vdebug("ttyGS%d: rx block %d/%d\n",
423 port->port_num, count, req->actual);
424 break;
425 }
426 port->n_read = 0;
427 }
428
429 list_move(&req->list, &port->read_pool);
430 port->read_started--;
431 }
432
433 /* Push from tty to ldisc; this is handled by a workqueue,
434 * so we won't get callbacks and can hold port_lock
435 */
436 if (do_push)
437 tty_flip_buffer_push(&port->port);
438
439
440 /* We want our data queue to become empty ASAP, keeping data
441 * in the tty and ldisc (not here). If we couldn't push any
442 * this time around, RX may be starved, so wait until next jiffy.
443 *
444 * We may leave non-empty queue only when there is a tty, and
445 * either it is throttled or there is no more room in flip buffer.
446 */
447 if (!list_empty(queue) && !tty_throttled(tty))
448 schedule_delayed_work(&port->push, 1);
449
450 /* If we're still connected, refill the USB RX queue. */
451 if (!disconnect && port->port_usb)
452 gs_start_rx(port);
453
454 spin_unlock_irq(&port->port_lock);
455}
456
457static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
458{
459 struct gs_port *port = ep->driver_data;
460
461 /* Queue all received data until the tty layer is ready for it. */
462 spin_lock(&port->port_lock);
463 list_add_tail(&req->list, &port->read_queue);
464 schedule_delayed_work(&port->push, 0);
465 spin_unlock(&port->port_lock);
466}
467
468static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
469{
470 struct gs_port *port = ep->driver_data;
471
472 spin_lock(&port->port_lock);
473 list_add(&req->list, &port->write_pool);
474 port->write_started--;
475
476 switch (req->status) {
477 default:
478 /* presumably a transient fault */
479 pr_warn("%s: unexpected %s status %d\n",
480 __func__, ep->name, req->status);
481 fallthrough;
482 case 0:
483 /* normal completion */
484 gs_start_tx(port);
485 break;
486
487 case -ESHUTDOWN:
488 /* disconnect */
489 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
490 break;
491 }
492
493 spin_unlock(&port->port_lock);
494}
495
496static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
497 int *allocated)
498{
499 struct usb_request *req;
500
501 while (!list_empty(head)) {
502 req = list_entry(head->next, struct usb_request, list);
503 list_del(&req->list);
504 gs_free_req(ep, req);
505 if (allocated)
506 (*allocated)--;
507 }
508}
509
510static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
511 void (*fn)(struct usb_ep *, struct usb_request *),
512 int *allocated)
513{
514 int i;
515 struct usb_request *req;
516 int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
517
518 /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
519 * do quite that many this time, don't fail ... we just won't
520 * be as speedy as we might otherwise be.
521 */
522 for (i = 0; i < n; i++) {
523 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
524 if (!req)
525 return list_empty(head) ? -ENOMEM : 0;
526 req->complete = fn;
527 list_add_tail(&req->list, head);
528 if (allocated)
529 (*allocated)++;
530 }
531 return 0;
532}
533
534/**
535 * gs_start_io - start USB I/O streams
536 * @port: port to use
537 * Context: holding port_lock; port_tty and port_usb are non-null
538 *
539 * We only start I/O when something is connected to both sides of
540 * this port. If nothing is listening on the host side, we may
541 * be pointlessly filling up our TX buffers and FIFO.
542 */
543static int gs_start_io(struct gs_port *port)
544{
545 struct list_head *head = &port->read_pool;
546 struct usb_ep *ep;
547 int status;
548 unsigned started;
549
550 if (!port->port_usb || !port->port.tty)
551 return -EIO;
552
553 /* Allocate RX and TX I/O buffers. We can't easily do this much
554 * earlier (with GFP_KERNEL) because the requests are coupled to
555 * endpoints, as are the packet sizes we'll be using. Different
556 * configurations may use different endpoints with a given port;
557 * and high speed vs full speed changes packet sizes too.
558 */
559 ep = port->port_usb->out;
560 status = gs_alloc_requests(ep, head, gs_read_complete,
561 &port->read_allocated);
562 if (status)
563 return status;
564
565 status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
566 gs_write_complete, &port->write_allocated);
567 if (status) {
568 gs_free_requests(ep, head, &port->read_allocated);
569 return status;
570 }
571
572 /* queue read requests */
573 port->n_read = 0;
574 started = gs_start_rx(port);
575
576 if (started) {
577 gs_start_tx(port);
578 /* Unblock any pending writes into our circular buffer, in case
579 * we didn't in gs_start_tx() */
580 tty_wakeup(port->port.tty);
581 } else {
582 /* Free reqs only if we are still connected */
583 if (port->port_usb) {
584 gs_free_requests(ep, head, &port->read_allocated);
585 gs_free_requests(port->port_usb->in, &port->write_pool,
586 &port->write_allocated);
587 }
588 status = -EIO;
589 }
590
591 return status;
592}
593
594/*-------------------------------------------------------------------------*/
595
596/* TTY Driver */
597
598/*
599 * gs_open sets up the link between a gs_port and its associated TTY.
600 * That link is broken *only* by TTY close(), and all driver methods
601 * know that.
602 */
603static int gs_open(struct tty_struct *tty, struct file *file)
604{
605 int port_num = tty->index;
606 struct gs_port *port;
607 int status = 0;
608
609 mutex_lock(&ports[port_num].lock);
610 port = ports[port_num].port;
611 if (!port) {
612 status = -ENODEV;
613 goto out;
614 }
615
616 spin_lock_irq(&port->port_lock);
617
618 /* allocate circular buffer on first open */
619 if (!kfifo_initialized(&port->port_write_buf)) {
620
621 spin_unlock_irq(&port->port_lock);
622
623 /*
624 * portmaster's mutex still protects from simultaneous open(),
625 * and close() can't happen, yet.
626 */
627
628 status = kfifo_alloc(&port->port_write_buf,
629 WRITE_BUF_SIZE, GFP_KERNEL);
630 if (status) {
631 pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
632 port_num, tty, file);
633 goto out;
634 }
635
636 spin_lock_irq(&port->port_lock);
637 }
638
639 /* already open? Great. */
640 if (port->port.count++)
641 goto exit_unlock_port;
642
643 tty->driver_data = port;
644 port->port.tty = tty;
645
646 /* if connected, start the I/O stream */
647 if (port->port_usb) {
648 /* if port is suspended, wait resume to start I/0 stream */
649 if (!port->suspended) {
650 struct gserial *gser = port->port_usb;
651
652 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
653 gs_start_io(port);
654
655 if (gser->connect)
656 gser->connect(gser);
657 } else {
658 pr_debug("delay start of ttyGS%d\n", port->port_num);
659 port->start_delayed = true;
660 }
661 }
662
663 pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
664
665exit_unlock_port:
666 spin_unlock_irq(&port->port_lock);
667out:
668 mutex_unlock(&ports[port_num].lock);
669 return status;
670}
671
672static int gs_close_flush_done(struct gs_port *p)
673{
674 int cond;
675
676 /* return true on disconnect or empty buffer or if raced with open() */
677 spin_lock_irq(&p->port_lock);
678 cond = p->port_usb == NULL || !kfifo_len(&p->port_write_buf) ||
679 p->port.count > 1;
680 spin_unlock_irq(&p->port_lock);
681
682 return cond;
683}
684
685static void gs_close(struct tty_struct *tty, struct file *file)
686{
687 struct gs_port *port = tty->driver_data;
688 struct gserial *gser;
689
690 spin_lock_irq(&port->port_lock);
691
692 if (port->port.count != 1) {
693raced_with_open:
694 if (port->port.count == 0)
695 WARN_ON(1);
696 else
697 --port->port.count;
698 goto exit;
699 }
700
701 pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
702
703 gser = port->port_usb;
704 if (gser && !port->suspended && gser->disconnect)
705 gser->disconnect(gser);
706
707 /* wait for circular write buffer to drain, disconnect, or at
708 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
709 */
710 if (kfifo_len(&port->port_write_buf) > 0 && gser) {
711 spin_unlock_irq(&port->port_lock);
712 wait_event_interruptible_timeout(port->drain_wait,
713 gs_close_flush_done(port),
714 GS_CLOSE_TIMEOUT * HZ);
715 spin_lock_irq(&port->port_lock);
716
717 if (port->port.count != 1)
718 goto raced_with_open;
719
720 gser = port->port_usb;
721 }
722
723 /* Iff we're disconnected, there can be no I/O in flight so it's
724 * ok to free the circular buffer; else just scrub it. And don't
725 * let the push async work fire again until we're re-opened.
726 */
727 if (gser == NULL)
728 kfifo_free(&port->port_write_buf);
729 else
730 kfifo_reset(&port->port_write_buf);
731
732 port->start_delayed = false;
733 port->port.count = 0;
734 port->port.tty = NULL;
735
736 pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
737 port->port_num, tty, file);
738
739 wake_up(&port->close_wait);
740exit:
741 spin_unlock_irq(&port->port_lock);
742}
743
744static ssize_t gs_write(struct tty_struct *tty, const u8 *buf, size_t count)
745{
746 struct gs_port *port = tty->driver_data;
747 unsigned long flags;
748
749 pr_vdebug("gs_write: ttyGS%d (%p) writing %zu bytes\n",
750 port->port_num, tty, count);
751
752 spin_lock_irqsave(&port->port_lock, flags);
753 if (count)
754 count = kfifo_in(&port->port_write_buf, buf, count);
755 /* treat count == 0 as flush_chars() */
756 if (port->port_usb)
757 gs_start_tx(port);
758 spin_unlock_irqrestore(&port->port_lock, flags);
759
760 return count;
761}
762
763static int gs_put_char(struct tty_struct *tty, u8 ch)
764{
765 struct gs_port *port = tty->driver_data;
766 unsigned long flags;
767 int status;
768
769 pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
770 port->port_num, tty, ch, __builtin_return_address(0));
771
772 spin_lock_irqsave(&port->port_lock, flags);
773 status = kfifo_put(&port->port_write_buf, ch);
774 spin_unlock_irqrestore(&port->port_lock, flags);
775
776 return status;
777}
778
779static void gs_flush_chars(struct tty_struct *tty)
780{
781 struct gs_port *port = tty->driver_data;
782 unsigned long flags;
783
784 pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
785
786 spin_lock_irqsave(&port->port_lock, flags);
787 if (port->port_usb)
788 gs_start_tx(port);
789 spin_unlock_irqrestore(&port->port_lock, flags);
790}
791
792static unsigned int gs_write_room(struct tty_struct *tty)
793{
794 struct gs_port *port = tty->driver_data;
795 unsigned long flags;
796 unsigned int room = 0;
797
798 spin_lock_irqsave(&port->port_lock, flags);
799 if (port->port_usb)
800 room = kfifo_avail(&port->port_write_buf);
801 spin_unlock_irqrestore(&port->port_lock, flags);
802
803 pr_vdebug("gs_write_room: (%d,%p) room=%u\n",
804 port->port_num, tty, room);
805
806 return room;
807}
808
809static unsigned int gs_chars_in_buffer(struct tty_struct *tty)
810{
811 struct gs_port *port = tty->driver_data;
812 unsigned long flags;
813 unsigned int chars;
814
815 spin_lock_irqsave(&port->port_lock, flags);
816 chars = kfifo_len(&port->port_write_buf);
817 spin_unlock_irqrestore(&port->port_lock, flags);
818
819 pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%u\n",
820 port->port_num, tty, chars);
821
822 return chars;
823}
824
825/* undo side effects of setting TTY_THROTTLED */
826static void gs_unthrottle(struct tty_struct *tty)
827{
828 struct gs_port *port = tty->driver_data;
829 unsigned long flags;
830
831 spin_lock_irqsave(&port->port_lock, flags);
832 if (port->port_usb) {
833 /* Kickstart read queue processing. We don't do xon/xoff,
834 * rts/cts, or other handshaking with the host, but if the
835 * read queue backs up enough we'll be NAKing OUT packets.
836 */
837 pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
838 schedule_delayed_work(&port->push, 0);
839 }
840 spin_unlock_irqrestore(&port->port_lock, flags);
841}
842
843static int gs_break_ctl(struct tty_struct *tty, int duration)
844{
845 struct gs_port *port = tty->driver_data;
846 int status = 0;
847 struct gserial *gser;
848
849 pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
850 port->port_num, duration);
851
852 spin_lock_irq(&port->port_lock);
853 gser = port->port_usb;
854 if (gser && gser->send_break)
855 status = gser->send_break(gser, duration);
856 spin_unlock_irq(&port->port_lock);
857
858 return status;
859}
860
861static int gs_get_icount(struct tty_struct *tty,
862 struct serial_icounter_struct *icount)
863{
864 struct gs_port *port = tty->driver_data;
865 struct async_icount cnow;
866 unsigned long flags;
867
868 spin_lock_irqsave(&port->port_lock, flags);
869 cnow = port->icount;
870 spin_unlock_irqrestore(&port->port_lock, flags);
871
872 icount->rx = cnow.rx;
873 icount->tx = cnow.tx;
874
875 return 0;
876}
877
878static const struct tty_operations gs_tty_ops = {
879 .open = gs_open,
880 .close = gs_close,
881 .write = gs_write,
882 .put_char = gs_put_char,
883 .flush_chars = gs_flush_chars,
884 .write_room = gs_write_room,
885 .chars_in_buffer = gs_chars_in_buffer,
886 .unthrottle = gs_unthrottle,
887 .break_ctl = gs_break_ctl,
888 .get_icount = gs_get_icount,
889};
890
891/*-------------------------------------------------------------------------*/
892
893static struct tty_driver *gs_tty_driver;
894
895#ifdef CONFIG_U_SERIAL_CONSOLE
896
897static void gs_console_complete_out(struct usb_ep *ep, struct usb_request *req)
898{
899 struct gs_console *cons = req->context;
900
901 switch (req->status) {
902 default:
903 pr_warn("%s: unexpected %s status %d\n",
904 __func__, ep->name, req->status);
905 fallthrough;
906 case 0:
907 /* normal completion */
908 spin_lock(&cons->lock);
909 req->length = 0;
910 schedule_work(&cons->work);
911 spin_unlock(&cons->lock);
912 break;
913 case -ECONNRESET:
914 case -ESHUTDOWN:
915 /* disconnect */
916 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
917 break;
918 }
919}
920
921static void __gs_console_push(struct gs_console *cons)
922{
923 struct usb_request *req = cons->req;
924 struct usb_ep *ep;
925 size_t size;
926
927 if (!req)
928 return; /* disconnected */
929
930 if (req->length)
931 return; /* busy */
932
933 ep = cons->console.data;
934 size = kfifo_out(&cons->buf, req->buf, ep->maxpacket);
935 if (!size)
936 return;
937
938 if (cons->missed && ep->maxpacket >= 64) {
939 char buf[64];
940 size_t len;
941
942 len = sprintf(buf, "\n[missed %zu bytes]\n", cons->missed);
943 kfifo_in(&cons->buf, buf, len);
944 cons->missed = 0;
945 }
946
947 req->length = size;
948
949 spin_unlock_irq(&cons->lock);
950 if (usb_ep_queue(ep, req, GFP_ATOMIC))
951 req->length = 0;
952 spin_lock_irq(&cons->lock);
953}
954
955static void gs_console_work(struct work_struct *work)
956{
957 struct gs_console *cons = container_of(work, struct gs_console, work);
958
959 spin_lock_irq(&cons->lock);
960
961 __gs_console_push(cons);
962
963 spin_unlock_irq(&cons->lock);
964}
965
966static void gs_console_write(struct console *co,
967 const char *buf, unsigned count)
968{
969 struct gs_console *cons = container_of(co, struct gs_console, console);
970 unsigned long flags;
971 size_t n;
972
973 spin_lock_irqsave(&cons->lock, flags);
974
975 n = kfifo_in(&cons->buf, buf, count);
976 if (n < count)
977 cons->missed += count - n;
978
979 if (cons->req && !cons->req->length)
980 schedule_work(&cons->work);
981
982 spin_unlock_irqrestore(&cons->lock, flags);
983}
984
985static struct tty_driver *gs_console_device(struct console *co, int *index)
986{
987 *index = co->index;
988 return gs_tty_driver;
989}
990
991static int gs_console_connect(struct gs_port *port)
992{
993 struct gs_console *cons = port->console;
994 struct usb_request *req;
995 struct usb_ep *ep;
996
997 if (!cons)
998 return 0;
999
1000 ep = port->port_usb->in;
1001 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
1002 if (!req)
1003 return -ENOMEM;
1004 req->complete = gs_console_complete_out;
1005 req->context = cons;
1006 req->length = 0;
1007
1008 spin_lock(&cons->lock);
1009 cons->req = req;
1010 cons->console.data = ep;
1011 spin_unlock(&cons->lock);
1012
1013 pr_debug("ttyGS%d: console connected!\n", port->port_num);
1014
1015 schedule_work(&cons->work);
1016
1017 return 0;
1018}
1019
1020static void gs_console_disconnect(struct gs_port *port)
1021{
1022 struct gs_console *cons = port->console;
1023 struct usb_request *req;
1024 struct usb_ep *ep;
1025
1026 if (!cons)
1027 return;
1028
1029 spin_lock(&cons->lock);
1030
1031 req = cons->req;
1032 ep = cons->console.data;
1033 cons->req = NULL;
1034
1035 spin_unlock(&cons->lock);
1036
1037 if (!req)
1038 return;
1039
1040 usb_ep_dequeue(ep, req);
1041 gs_free_req(ep, req);
1042}
1043
1044static int gs_console_init(struct gs_port *port)
1045{
1046 struct gs_console *cons;
1047 int err;
1048
1049 if (port->console)
1050 return 0;
1051
1052 cons = kzalloc(sizeof(*port->console), GFP_KERNEL);
1053 if (!cons)
1054 return -ENOMEM;
1055
1056 strcpy(cons->console.name, "ttyGS");
1057 cons->console.write = gs_console_write;
1058 cons->console.device = gs_console_device;
1059 cons->console.flags = CON_PRINTBUFFER;
1060 cons->console.index = port->port_num;
1061
1062 INIT_WORK(&cons->work, gs_console_work);
1063 spin_lock_init(&cons->lock);
1064
1065 err = kfifo_alloc(&cons->buf, GS_CONSOLE_BUF_SIZE, GFP_KERNEL);
1066 if (err) {
1067 pr_err("ttyGS%d: allocate console buffer failed\n", port->port_num);
1068 kfree(cons);
1069 return err;
1070 }
1071
1072 port->console = cons;
1073 register_console(&cons->console);
1074
1075 spin_lock_irq(&port->port_lock);
1076 if (port->port_usb)
1077 gs_console_connect(port);
1078 spin_unlock_irq(&port->port_lock);
1079
1080 return 0;
1081}
1082
1083static void gs_console_exit(struct gs_port *port)
1084{
1085 struct gs_console *cons = port->console;
1086
1087 if (!cons)
1088 return;
1089
1090 unregister_console(&cons->console);
1091
1092 spin_lock_irq(&port->port_lock);
1093 if (cons->req)
1094 gs_console_disconnect(port);
1095 spin_unlock_irq(&port->port_lock);
1096
1097 cancel_work_sync(&cons->work);
1098 kfifo_free(&cons->buf);
1099 kfree(cons);
1100 port->console = NULL;
1101}
1102
1103ssize_t gserial_set_console(unsigned char port_num, const char *page, size_t count)
1104{
1105 struct gs_port *port;
1106 bool enable;
1107 int ret;
1108
1109 ret = kstrtobool(page, &enable);
1110 if (ret)
1111 return ret;
1112
1113 mutex_lock(&ports[port_num].lock);
1114 port = ports[port_num].port;
1115
1116 if (WARN_ON(port == NULL)) {
1117 ret = -ENXIO;
1118 goto out;
1119 }
1120
1121 if (enable)
1122 ret = gs_console_init(port);
1123 else
1124 gs_console_exit(port);
1125out:
1126 mutex_unlock(&ports[port_num].lock);
1127
1128 return ret < 0 ? ret : count;
1129}
1130EXPORT_SYMBOL_GPL(gserial_set_console);
1131
1132ssize_t gserial_get_console(unsigned char port_num, char *page)
1133{
1134 struct gs_port *port;
1135 ssize_t ret;
1136
1137 mutex_lock(&ports[port_num].lock);
1138 port = ports[port_num].port;
1139
1140 if (WARN_ON(port == NULL))
1141 ret = -ENXIO;
1142 else
1143 ret = sprintf(page, "%u\n", !!port->console);
1144
1145 mutex_unlock(&ports[port_num].lock);
1146
1147 return ret;
1148}
1149EXPORT_SYMBOL_GPL(gserial_get_console);
1150
1151#else
1152
1153static int gs_console_connect(struct gs_port *port)
1154{
1155 return 0;
1156}
1157
1158static void gs_console_disconnect(struct gs_port *port)
1159{
1160}
1161
1162static int gs_console_init(struct gs_port *port)
1163{
1164 return -ENOSYS;
1165}
1166
1167static void gs_console_exit(struct gs_port *port)
1168{
1169}
1170
1171#endif
1172
1173static int
1174gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1175{
1176 struct gs_port *port;
1177 int ret = 0;
1178
1179 mutex_lock(&ports[port_num].lock);
1180 if (ports[port_num].port) {
1181 ret = -EBUSY;
1182 goto out;
1183 }
1184
1185 port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1186 if (port == NULL) {
1187 ret = -ENOMEM;
1188 goto out;
1189 }
1190
1191 tty_port_init(&port->port);
1192 spin_lock_init(&port->port_lock);
1193 init_waitqueue_head(&port->drain_wait);
1194 init_waitqueue_head(&port->close_wait);
1195
1196 INIT_DELAYED_WORK(&port->push, gs_rx_push);
1197
1198 INIT_LIST_HEAD(&port->read_pool);
1199 INIT_LIST_HEAD(&port->read_queue);
1200 INIT_LIST_HEAD(&port->write_pool);
1201
1202 port->port_num = port_num;
1203 port->port_line_coding = *coding;
1204
1205 ports[port_num].port = port;
1206out:
1207 mutex_unlock(&ports[port_num].lock);
1208 return ret;
1209}
1210
1211static int gs_closed(struct gs_port *port)
1212{
1213 int cond;
1214
1215 spin_lock_irq(&port->port_lock);
1216 cond = port->port.count == 0;
1217 spin_unlock_irq(&port->port_lock);
1218
1219 return cond;
1220}
1221
1222static void gserial_free_port(struct gs_port *port)
1223{
1224 cancel_delayed_work_sync(&port->push);
1225 /* wait for old opens to finish */
1226 wait_event(port->close_wait, gs_closed(port));
1227 WARN_ON(port->port_usb != NULL);
1228 tty_port_destroy(&port->port);
1229 kfree(port);
1230}
1231
1232void gserial_free_line(unsigned char port_num)
1233{
1234 struct gs_port *port;
1235
1236 mutex_lock(&ports[port_num].lock);
1237 if (!ports[port_num].port) {
1238 mutex_unlock(&ports[port_num].lock);
1239 return;
1240 }
1241 port = ports[port_num].port;
1242 gs_console_exit(port);
1243 ports[port_num].port = NULL;
1244 mutex_unlock(&ports[port_num].lock);
1245
1246 gserial_free_port(port);
1247 tty_unregister_device(gs_tty_driver, port_num);
1248}
1249EXPORT_SYMBOL_GPL(gserial_free_line);
1250
1251int gserial_alloc_line_no_console(unsigned char *line_num)
1252{
1253 struct usb_cdc_line_coding coding;
1254 struct gs_port *port;
1255 struct device *tty_dev;
1256 int ret;
1257 int port_num;
1258
1259 coding.dwDTERate = cpu_to_le32(9600);
1260 coding.bCharFormat = 8;
1261 coding.bParityType = USB_CDC_NO_PARITY;
1262 coding.bDataBits = USB_CDC_1_STOP_BITS;
1263
1264 for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1265 ret = gs_port_alloc(port_num, &coding);
1266 if (ret == -EBUSY)
1267 continue;
1268 if (ret)
1269 return ret;
1270 break;
1271 }
1272 if (ret)
1273 return ret;
1274
1275 /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1276
1277 port = ports[port_num].port;
1278 tty_dev = tty_port_register_device(&port->port,
1279 gs_tty_driver, port_num, NULL);
1280 if (IS_ERR(tty_dev)) {
1281 pr_err("%s: failed to register tty for port %d, err %ld\n",
1282 __func__, port_num, PTR_ERR(tty_dev));
1283
1284 ret = PTR_ERR(tty_dev);
1285 mutex_lock(&ports[port_num].lock);
1286 ports[port_num].port = NULL;
1287 mutex_unlock(&ports[port_num].lock);
1288 gserial_free_port(port);
1289 goto err;
1290 }
1291 *line_num = port_num;
1292err:
1293 return ret;
1294}
1295EXPORT_SYMBOL_GPL(gserial_alloc_line_no_console);
1296
1297int gserial_alloc_line(unsigned char *line_num)
1298{
1299 int ret = gserial_alloc_line_no_console(line_num);
1300
1301 if (!ret && !*line_num)
1302 gs_console_init(ports[*line_num].port);
1303
1304 return ret;
1305}
1306EXPORT_SYMBOL_GPL(gserial_alloc_line);
1307
1308/**
1309 * gserial_connect - notify TTY I/O glue that USB link is active
1310 * @gser: the function, set up with endpoints and descriptors
1311 * @port_num: which port is active
1312 * Context: any (usually from irq)
1313 *
1314 * This is called activate endpoints and let the TTY layer know that
1315 * the connection is active ... not unlike "carrier detect". It won't
1316 * necessarily start I/O queues; unless the TTY is held open by any
1317 * task, there would be no point. However, the endpoints will be
1318 * activated so the USB host can perform I/O, subject to basic USB
1319 * hardware flow control.
1320 *
1321 * Caller needs to have set up the endpoints and USB function in @dev
1322 * before calling this, as well as the appropriate (speed-specific)
1323 * endpoint descriptors, and also have allocate @port_num by calling
1324 * @gserial_alloc_line().
1325 *
1326 * Returns negative errno or zero.
1327 * On success, ep->driver_data will be overwritten.
1328 */
1329int gserial_connect(struct gserial *gser, u8 port_num)
1330{
1331 struct gs_port *port;
1332 unsigned long flags;
1333 int status;
1334
1335 if (port_num >= MAX_U_SERIAL_PORTS)
1336 return -ENXIO;
1337
1338 port = ports[port_num].port;
1339 if (!port) {
1340 pr_err("serial line %d not allocated.\n", port_num);
1341 return -EINVAL;
1342 }
1343 if (port->port_usb) {
1344 pr_err("serial line %d is in use.\n", port_num);
1345 return -EBUSY;
1346 }
1347
1348 /* activate the endpoints */
1349 status = usb_ep_enable(gser->in);
1350 if (status < 0)
1351 return status;
1352 gser->in->driver_data = port;
1353
1354 status = usb_ep_enable(gser->out);
1355 if (status < 0)
1356 goto fail_out;
1357 gser->out->driver_data = port;
1358
1359 /* then tell the tty glue that I/O can work */
1360 spin_lock_irqsave(&port->port_lock, flags);
1361 gser->ioport = port;
1362 port->port_usb = gser;
1363
1364 /* REVISIT unclear how best to handle this state...
1365 * we don't really couple it with the Linux TTY.
1366 */
1367 gser->port_line_coding = port->port_line_coding;
1368
1369 /* REVISIT if waiting on "carrier detect", signal. */
1370
1371 /* if it's already open, start I/O ... and notify the serial
1372 * protocol about open/close status (connect/disconnect).
1373 */
1374 if (port->port.count) {
1375 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1376 gs_start_io(port);
1377 if (gser->connect)
1378 gser->connect(gser);
1379 } else {
1380 if (gser->disconnect)
1381 gser->disconnect(gser);
1382 }
1383
1384 status = gs_console_connect(port);
1385 spin_unlock_irqrestore(&port->port_lock, flags);
1386
1387 return status;
1388
1389fail_out:
1390 usb_ep_disable(gser->in);
1391 return status;
1392}
1393EXPORT_SYMBOL_GPL(gserial_connect);
1394/**
1395 * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1396 * @gser: the function, on which gserial_connect() was called
1397 * Context: any (usually from irq)
1398 *
1399 * This is called to deactivate endpoints and let the TTY layer know
1400 * that the connection went inactive ... not unlike "hangup".
1401 *
1402 * On return, the state is as if gserial_connect() had never been called;
1403 * there is no active USB I/O on these endpoints.
1404 */
1405void gserial_disconnect(struct gserial *gser)
1406{
1407 struct gs_port *port = gser->ioport;
1408 unsigned long flags;
1409
1410 if (!port)
1411 return;
1412
1413 spin_lock_irqsave(&serial_port_lock, flags);
1414
1415 /* tell the TTY glue not to do I/O here any more */
1416 spin_lock(&port->port_lock);
1417
1418 gs_console_disconnect(port);
1419
1420 /* REVISIT as above: how best to track this? */
1421 port->port_line_coding = gser->port_line_coding;
1422
1423 port->port_usb = NULL;
1424 gser->ioport = NULL;
1425 if (port->port.count > 0) {
1426 wake_up_interruptible(&port->drain_wait);
1427 if (port->port.tty)
1428 tty_hangup(port->port.tty);
1429 }
1430 port->suspended = false;
1431 spin_unlock(&port->port_lock);
1432 spin_unlock_irqrestore(&serial_port_lock, flags);
1433
1434 /* disable endpoints, aborting down any active I/O */
1435 usb_ep_disable(gser->out);
1436 usb_ep_disable(gser->in);
1437
1438 /* finally, free any unused/unusable I/O buffers */
1439 spin_lock_irqsave(&port->port_lock, flags);
1440 if (port->port.count == 0)
1441 kfifo_free(&port->port_write_buf);
1442 gs_free_requests(gser->out, &port->read_pool, NULL);
1443 gs_free_requests(gser->out, &port->read_queue, NULL);
1444 gs_free_requests(gser->in, &port->write_pool, NULL);
1445
1446 port->read_allocated = port->read_started =
1447 port->write_allocated = port->write_started = 0;
1448
1449 spin_unlock_irqrestore(&port->port_lock, flags);
1450}
1451EXPORT_SYMBOL_GPL(gserial_disconnect);
1452
1453void gserial_suspend(struct gserial *gser)
1454{
1455 struct gs_port *port;
1456 unsigned long flags;
1457
1458 spin_lock_irqsave(&serial_port_lock, flags);
1459 port = gser->ioport;
1460
1461 if (!port) {
1462 spin_unlock_irqrestore(&serial_port_lock, flags);
1463 return;
1464 }
1465
1466 spin_lock(&port->port_lock);
1467 spin_unlock(&serial_port_lock);
1468 port->suspended = true;
1469 port->start_delayed = true;
1470 spin_unlock_irqrestore(&port->port_lock, flags);
1471}
1472EXPORT_SYMBOL_GPL(gserial_suspend);
1473
1474void gserial_resume(struct gserial *gser)
1475{
1476 struct gs_port *port;
1477 unsigned long flags;
1478
1479 spin_lock_irqsave(&serial_port_lock, flags);
1480 port = gser->ioport;
1481
1482 if (!port) {
1483 spin_unlock_irqrestore(&serial_port_lock, flags);
1484 return;
1485 }
1486
1487 spin_lock(&port->port_lock);
1488 spin_unlock(&serial_port_lock);
1489 port->suspended = false;
1490 if (!port->start_delayed) {
1491 spin_unlock_irqrestore(&port->port_lock, flags);
1492 return;
1493 }
1494
1495 pr_debug("delayed start ttyGS%d\n", port->port_num);
1496 gs_start_io(port);
1497 if (gser->connect)
1498 gser->connect(gser);
1499 port->start_delayed = false;
1500 spin_unlock_irqrestore(&port->port_lock, flags);
1501}
1502EXPORT_SYMBOL_GPL(gserial_resume);
1503
1504static int __init userial_init(void)
1505{
1506 struct tty_driver *driver;
1507 unsigned i;
1508 int status;
1509
1510 driver = tty_alloc_driver(MAX_U_SERIAL_PORTS, TTY_DRIVER_REAL_RAW |
1511 TTY_DRIVER_DYNAMIC_DEV);
1512 if (IS_ERR(driver))
1513 return PTR_ERR(driver);
1514
1515 driver->driver_name = "g_serial";
1516 driver->name = "ttyGS";
1517 /* uses dynamically assigned dev_t values */
1518
1519 driver->type = TTY_DRIVER_TYPE_SERIAL;
1520 driver->subtype = SERIAL_TYPE_NORMAL;
1521 driver->init_termios = tty_std_termios;
1522
1523 /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1524 * MS-Windows. Otherwise, most of these flags shouldn't affect
1525 * anything unless we were to actually hook up to a serial line.
1526 */
1527 driver->init_termios.c_cflag =
1528 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1529 driver->init_termios.c_ispeed = 9600;
1530 driver->init_termios.c_ospeed = 9600;
1531
1532 tty_set_operations(driver, &gs_tty_ops);
1533 for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1534 mutex_init(&ports[i].lock);
1535
1536 /* export the driver ... */
1537 status = tty_register_driver(driver);
1538 if (status) {
1539 pr_err("%s: cannot register, err %d\n",
1540 __func__, status);
1541 goto fail;
1542 }
1543
1544 gs_tty_driver = driver;
1545
1546 pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1547 MAX_U_SERIAL_PORTS,
1548 (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1549
1550 return status;
1551fail:
1552 tty_driver_kref_put(driver);
1553 return status;
1554}
1555module_init(userial_init);
1556
1557static void __exit userial_cleanup(void)
1558{
1559 tty_unregister_driver(gs_tty_driver);
1560 tty_driver_kref_put(gs_tty_driver);
1561 gs_tty_driver = NULL;
1562}
1563module_exit(userial_cleanup);
1564
1565MODULE_DESCRIPTION("utilities for USB gadget \"serial port\"/TTY support");
1566MODULE_LICENSE("GPL");
1/*
2 * u_serial.c - utilities for USB gadget "serial port"/TTY support
3 *
4 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
5 * Copyright (C) 2008 David Brownell
6 * Copyright (C) 2008 by Nokia Corporation
7 *
8 * This code also borrows from usbserial.c, which is
9 * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
10 * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
11 * Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
12 *
13 * This software is distributed under the terms of the GNU General
14 * Public License ("GPL") as published by the Free Software Foundation,
15 * either version 2 of that License or (at your option) any later version.
16 */
17
18/* #define VERBOSE_DEBUG */
19
20#include <linux/kernel.h>
21#include <linux/sched.h>
22#include <linux/interrupt.h>
23#include <linux/device.h>
24#include <linux/delay.h>
25#include <linux/tty.h>
26#include <linux/tty_flip.h>
27#include <linux/slab.h>
28#include <linux/export.h>
29#include <linux/module.h>
30#include <linux/console.h>
31#include <linux/kthread.h>
32
33#include "u_serial.h"
34
35
36/*
37 * This component encapsulates the TTY layer glue needed to provide basic
38 * "serial port" functionality through the USB gadget stack. Each such
39 * port is exposed through a /dev/ttyGS* node.
40 *
41 * After this module has been loaded, the individual TTY port can be requested
42 * (gserial_alloc_line()) and it will stay available until they are removed
43 * (gserial_free_line()). Each one may be connected to a USB function
44 * (gserial_connect), or disconnected (with gserial_disconnect) when the USB
45 * host issues a config change event. Data can only flow when the port is
46 * connected to the host.
47 *
48 * A given TTY port can be made available in multiple configurations.
49 * For example, each one might expose a ttyGS0 node which provides a
50 * login application. In one case that might use CDC ACM interface 0,
51 * while another configuration might use interface 3 for that. The
52 * work to handle that (including descriptor management) is not part
53 * of this component.
54 *
55 * Configurations may expose more than one TTY port. For example, if
56 * ttyGS0 provides login service, then ttyGS1 might provide dialer access
57 * for a telephone or fax link. And ttyGS2 might be something that just
58 * needs a simple byte stream interface for some messaging protocol that
59 * is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
60 *
61 *
62 * gserial is the lifecycle interface, used by USB functions
63 * gs_port is the I/O nexus, used by the tty driver
64 * tty_struct links to the tty/filesystem framework
65 *
66 * gserial <---> gs_port ... links will be null when the USB link is
67 * inactive; managed by gserial_{connect,disconnect}(). each gserial
68 * instance can wrap its own USB control protocol.
69 * gserial->ioport == usb_ep->driver_data ... gs_port
70 * gs_port->port_usb ... gserial
71 *
72 * gs_port <---> tty_struct ... links will be null when the TTY file
73 * isn't opened; managed by gs_open()/gs_close()
74 * gserial->port_tty ... tty_struct
75 * tty_struct->driver_data ... gserial
76 */
77
78/* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
79 * next layer of buffering. For TX that's a circular buffer; for RX
80 * consider it a NOP. A third layer is provided by the TTY code.
81 */
82#define QUEUE_SIZE 16
83#define WRITE_BUF_SIZE 8192 /* TX only */
84#define GS_CONSOLE_BUF_SIZE 8192
85
86/* circular buffer */
87struct gs_buf {
88 unsigned buf_size;
89 char *buf_buf;
90 char *buf_get;
91 char *buf_put;
92};
93
94/* console info */
95struct gscons_info {
96 struct gs_port *port;
97 struct task_struct *console_thread;
98 struct gs_buf con_buf;
99 /* protect the buf and busy flag */
100 spinlock_t con_lock;
101 int req_busy;
102 struct usb_request *console_req;
103};
104
105/*
106 * The port structure holds info for each port, one for each minor number
107 * (and thus for each /dev/ node).
108 */
109struct gs_port {
110 struct tty_port port;
111 spinlock_t port_lock; /* guard port_* access */
112
113 struct gserial *port_usb;
114
115 bool openclose; /* open/close in progress */
116 u8 port_num;
117
118 struct list_head read_pool;
119 int read_started;
120 int read_allocated;
121 struct list_head read_queue;
122 unsigned n_read;
123 struct tasklet_struct push;
124
125 struct list_head write_pool;
126 int write_started;
127 int write_allocated;
128 struct gs_buf port_write_buf;
129 wait_queue_head_t drain_wait; /* wait while writes drain */
130 bool write_busy;
131 wait_queue_head_t close_wait;
132
133 /* REVISIT this state ... */
134 struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
135};
136
137static struct portmaster {
138 struct mutex lock; /* protect open/close */
139 struct gs_port *port;
140} ports[MAX_U_SERIAL_PORTS];
141
142#define GS_CLOSE_TIMEOUT 15 /* seconds */
143
144
145
146#ifdef VERBOSE_DEBUG
147#ifndef pr_vdebug
148#define pr_vdebug(fmt, arg...) \
149 pr_debug(fmt, ##arg)
150#endif /* pr_vdebug */
151#else
152#ifndef pr_vdebug
153#define pr_vdebug(fmt, arg...) \
154 ({ if (0) pr_debug(fmt, ##arg); })
155#endif /* pr_vdebug */
156#endif
157
158/*-------------------------------------------------------------------------*/
159
160/* Circular Buffer */
161
162/*
163 * gs_buf_alloc
164 *
165 * Allocate a circular buffer and all associated memory.
166 */
167static int gs_buf_alloc(struct gs_buf *gb, unsigned size)
168{
169 gb->buf_buf = kmalloc(size, GFP_KERNEL);
170 if (gb->buf_buf == NULL)
171 return -ENOMEM;
172
173 gb->buf_size = size;
174 gb->buf_put = gb->buf_buf;
175 gb->buf_get = gb->buf_buf;
176
177 return 0;
178}
179
180/*
181 * gs_buf_free
182 *
183 * Free the buffer and all associated memory.
184 */
185static void gs_buf_free(struct gs_buf *gb)
186{
187 kfree(gb->buf_buf);
188 gb->buf_buf = NULL;
189}
190
191/*
192 * gs_buf_clear
193 *
194 * Clear out all data in the circular buffer.
195 */
196static void gs_buf_clear(struct gs_buf *gb)
197{
198 gb->buf_get = gb->buf_put;
199 /* equivalent to a get of all data available */
200}
201
202/*
203 * gs_buf_data_avail
204 *
205 * Return the number of bytes of data written into the circular
206 * buffer.
207 */
208static unsigned gs_buf_data_avail(struct gs_buf *gb)
209{
210 return (gb->buf_size + gb->buf_put - gb->buf_get) % gb->buf_size;
211}
212
213/*
214 * gs_buf_space_avail
215 *
216 * Return the number of bytes of space available in the circular
217 * buffer.
218 */
219static unsigned gs_buf_space_avail(struct gs_buf *gb)
220{
221 return (gb->buf_size + gb->buf_get - gb->buf_put - 1) % gb->buf_size;
222}
223
224/*
225 * gs_buf_put
226 *
227 * Copy data data from a user buffer and put it into the circular buffer.
228 * Restrict to the amount of space available.
229 *
230 * Return the number of bytes copied.
231 */
232static unsigned
233gs_buf_put(struct gs_buf *gb, const char *buf, unsigned count)
234{
235 unsigned len;
236
237 len = gs_buf_space_avail(gb);
238 if (count > len)
239 count = len;
240
241 if (count == 0)
242 return 0;
243
244 len = gb->buf_buf + gb->buf_size - gb->buf_put;
245 if (count > len) {
246 memcpy(gb->buf_put, buf, len);
247 memcpy(gb->buf_buf, buf+len, count - len);
248 gb->buf_put = gb->buf_buf + count - len;
249 } else {
250 memcpy(gb->buf_put, buf, count);
251 if (count < len)
252 gb->buf_put += count;
253 else /* count == len */
254 gb->buf_put = gb->buf_buf;
255 }
256
257 return count;
258}
259
260/*
261 * gs_buf_get
262 *
263 * Get data from the circular buffer and copy to the given buffer.
264 * Restrict to the amount of data available.
265 *
266 * Return the number of bytes copied.
267 */
268static unsigned
269gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
270{
271 unsigned len;
272
273 len = gs_buf_data_avail(gb);
274 if (count > len)
275 count = len;
276
277 if (count == 0)
278 return 0;
279
280 len = gb->buf_buf + gb->buf_size - gb->buf_get;
281 if (count > len) {
282 memcpy(buf, gb->buf_get, len);
283 memcpy(buf+len, gb->buf_buf, count - len);
284 gb->buf_get = gb->buf_buf + count - len;
285 } else {
286 memcpy(buf, gb->buf_get, count);
287 if (count < len)
288 gb->buf_get += count;
289 else /* count == len */
290 gb->buf_get = gb->buf_buf;
291 }
292
293 return count;
294}
295
296/*-------------------------------------------------------------------------*/
297
298/* I/O glue between TTY (upper) and USB function (lower) driver layers */
299
300/*
301 * gs_alloc_req
302 *
303 * Allocate a usb_request and its buffer. Returns a pointer to the
304 * usb_request or NULL if there is an error.
305 */
306struct usb_request *
307gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
308{
309 struct usb_request *req;
310
311 req = usb_ep_alloc_request(ep, kmalloc_flags);
312
313 if (req != NULL) {
314 req->length = len;
315 req->buf = kmalloc(len, kmalloc_flags);
316 if (req->buf == NULL) {
317 usb_ep_free_request(ep, req);
318 return NULL;
319 }
320 }
321
322 return req;
323}
324EXPORT_SYMBOL_GPL(gs_alloc_req);
325
326/*
327 * gs_free_req
328 *
329 * Free a usb_request and its buffer.
330 */
331void gs_free_req(struct usb_ep *ep, struct usb_request *req)
332{
333 kfree(req->buf);
334 usb_ep_free_request(ep, req);
335}
336EXPORT_SYMBOL_GPL(gs_free_req);
337
338/*
339 * gs_send_packet
340 *
341 * If there is data to send, a packet is built in the given
342 * buffer and the size is returned. If there is no data to
343 * send, 0 is returned.
344 *
345 * Called with port_lock held.
346 */
347static unsigned
348gs_send_packet(struct gs_port *port, char *packet, unsigned size)
349{
350 unsigned len;
351
352 len = gs_buf_data_avail(&port->port_write_buf);
353 if (len < size)
354 size = len;
355 if (size != 0)
356 size = gs_buf_get(&port->port_write_buf, packet, size);
357 return size;
358}
359
360/*
361 * gs_start_tx
362 *
363 * This function finds available write requests, calls
364 * gs_send_packet to fill these packets with data, and
365 * continues until either there are no more write requests
366 * available or no more data to send. This function is
367 * run whenever data arrives or write requests are available.
368 *
369 * Context: caller owns port_lock; port_usb is non-null.
370 */
371static int gs_start_tx(struct gs_port *port)
372/*
373__releases(&port->port_lock)
374__acquires(&port->port_lock)
375*/
376{
377 struct list_head *pool = &port->write_pool;
378 struct usb_ep *in = port->port_usb->in;
379 int status = 0;
380 bool do_tty_wake = false;
381
382 while (!port->write_busy && !list_empty(pool)) {
383 struct usb_request *req;
384 int len;
385
386 if (port->write_started >= QUEUE_SIZE)
387 break;
388
389 req = list_entry(pool->next, struct usb_request, list);
390 len = gs_send_packet(port, req->buf, in->maxpacket);
391 if (len == 0) {
392 wake_up_interruptible(&port->drain_wait);
393 break;
394 }
395 do_tty_wake = true;
396
397 req->length = len;
398 list_del(&req->list);
399 req->zero = (gs_buf_data_avail(&port->port_write_buf) == 0);
400
401 pr_vdebug("ttyGS%d: tx len=%d, 0x%02x 0x%02x 0x%02x ...\n",
402 port->port_num, len, *((u8 *)req->buf),
403 *((u8 *)req->buf+1), *((u8 *)req->buf+2));
404
405 /* Drop lock while we call out of driver; completions
406 * could be issued while we do so. Disconnection may
407 * happen too; maybe immediately before we queue this!
408 *
409 * NOTE that we may keep sending data for a while after
410 * the TTY closed (dev->ioport->port_tty is NULL).
411 */
412 port->write_busy = true;
413 spin_unlock(&port->port_lock);
414 status = usb_ep_queue(in, req, GFP_ATOMIC);
415 spin_lock(&port->port_lock);
416 port->write_busy = false;
417
418 if (status) {
419 pr_debug("%s: %s %s err %d\n",
420 __func__, "queue", in->name, status);
421 list_add(&req->list, pool);
422 break;
423 }
424
425 port->write_started++;
426
427 /* abort immediately after disconnect */
428 if (!port->port_usb)
429 break;
430 }
431
432 if (do_tty_wake && port->port.tty)
433 tty_wakeup(port->port.tty);
434 return status;
435}
436
437/*
438 * Context: caller owns port_lock, and port_usb is set
439 */
440static unsigned gs_start_rx(struct gs_port *port)
441/*
442__releases(&port->port_lock)
443__acquires(&port->port_lock)
444*/
445{
446 struct list_head *pool = &port->read_pool;
447 struct usb_ep *out = port->port_usb->out;
448
449 while (!list_empty(pool)) {
450 struct usb_request *req;
451 int status;
452 struct tty_struct *tty;
453
454 /* no more rx if closed */
455 tty = port->port.tty;
456 if (!tty)
457 break;
458
459 if (port->read_started >= QUEUE_SIZE)
460 break;
461
462 req = list_entry(pool->next, struct usb_request, list);
463 list_del(&req->list);
464 req->length = out->maxpacket;
465
466 /* drop lock while we call out; the controller driver
467 * may need to call us back (e.g. for disconnect)
468 */
469 spin_unlock(&port->port_lock);
470 status = usb_ep_queue(out, req, GFP_ATOMIC);
471 spin_lock(&port->port_lock);
472
473 if (status) {
474 pr_debug("%s: %s %s err %d\n",
475 __func__, "queue", out->name, status);
476 list_add(&req->list, pool);
477 break;
478 }
479 port->read_started++;
480
481 /* abort immediately after disconnect */
482 if (!port->port_usb)
483 break;
484 }
485 return port->read_started;
486}
487
488/*
489 * RX tasklet takes data out of the RX queue and hands it up to the TTY
490 * layer until it refuses to take any more data (or is throttled back).
491 * Then it issues reads for any further data.
492 *
493 * If the RX queue becomes full enough that no usb_request is queued,
494 * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
495 * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
496 * can be buffered before the TTY layer's buffers (currently 64 KB).
497 */
498static void gs_rx_push(unsigned long _port)
499{
500 struct gs_port *port = (void *)_port;
501 struct tty_struct *tty;
502 struct list_head *queue = &port->read_queue;
503 bool disconnect = false;
504 bool do_push = false;
505
506 /* hand any queued data to the tty */
507 spin_lock_irq(&port->port_lock);
508 tty = port->port.tty;
509 while (!list_empty(queue)) {
510 struct usb_request *req;
511
512 req = list_first_entry(queue, struct usb_request, list);
513
514 /* leave data queued if tty was rx throttled */
515 if (tty && test_bit(TTY_THROTTLED, &tty->flags))
516 break;
517
518 switch (req->status) {
519 case -ESHUTDOWN:
520 disconnect = true;
521 pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
522 break;
523
524 default:
525 /* presumably a transient fault */
526 pr_warn("ttyGS%d: unexpected RX status %d\n",
527 port->port_num, req->status);
528 /* FALLTHROUGH */
529 case 0:
530 /* normal completion */
531 break;
532 }
533
534 /* push data to (open) tty */
535 if (req->actual) {
536 char *packet = req->buf;
537 unsigned size = req->actual;
538 unsigned n;
539 int count;
540
541 /* we may have pushed part of this packet already... */
542 n = port->n_read;
543 if (n) {
544 packet += n;
545 size -= n;
546 }
547
548 count = tty_insert_flip_string(&port->port, packet,
549 size);
550 if (count)
551 do_push = true;
552 if (count != size) {
553 /* stop pushing; TTY layer can't handle more */
554 port->n_read += count;
555 pr_vdebug("ttyGS%d: rx block %d/%d\n",
556 port->port_num, count, req->actual);
557 break;
558 }
559 port->n_read = 0;
560 }
561
562 list_move(&req->list, &port->read_pool);
563 port->read_started--;
564 }
565
566 /* Push from tty to ldisc; this is handled by a workqueue,
567 * so we won't get callbacks and can hold port_lock
568 */
569 if (do_push)
570 tty_flip_buffer_push(&port->port);
571
572
573 /* We want our data queue to become empty ASAP, keeping data
574 * in the tty and ldisc (not here). If we couldn't push any
575 * this time around, there may be trouble unless there's an
576 * implicit tty_unthrottle() call on its way...
577 *
578 * REVISIT we should probably add a timer to keep the tasklet
579 * from starving ... but it's not clear that case ever happens.
580 */
581 if (!list_empty(queue) && tty) {
582 if (!test_bit(TTY_THROTTLED, &tty->flags)) {
583 if (do_push)
584 tasklet_schedule(&port->push);
585 else
586 pr_warn("ttyGS%d: RX not scheduled?\n",
587 port->port_num);
588 }
589 }
590
591 /* If we're still connected, refill the USB RX queue. */
592 if (!disconnect && port->port_usb)
593 gs_start_rx(port);
594
595 spin_unlock_irq(&port->port_lock);
596}
597
598static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
599{
600 struct gs_port *port = ep->driver_data;
601
602 /* Queue all received data until the tty layer is ready for it. */
603 spin_lock(&port->port_lock);
604 list_add_tail(&req->list, &port->read_queue);
605 tasklet_schedule(&port->push);
606 spin_unlock(&port->port_lock);
607}
608
609static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
610{
611 struct gs_port *port = ep->driver_data;
612
613 spin_lock(&port->port_lock);
614 list_add(&req->list, &port->write_pool);
615 port->write_started--;
616
617 switch (req->status) {
618 default:
619 /* presumably a transient fault */
620 pr_warning("%s: unexpected %s status %d\n",
621 __func__, ep->name, req->status);
622 /* FALL THROUGH */
623 case 0:
624 /* normal completion */
625 gs_start_tx(port);
626 break;
627
628 case -ESHUTDOWN:
629 /* disconnect */
630 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
631 break;
632 }
633
634 spin_unlock(&port->port_lock);
635}
636
637static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
638 int *allocated)
639{
640 struct usb_request *req;
641
642 while (!list_empty(head)) {
643 req = list_entry(head->next, struct usb_request, list);
644 list_del(&req->list);
645 gs_free_req(ep, req);
646 if (allocated)
647 (*allocated)--;
648 }
649}
650
651static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
652 void (*fn)(struct usb_ep *, struct usb_request *),
653 int *allocated)
654{
655 int i;
656 struct usb_request *req;
657 int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
658
659 /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
660 * do quite that many this time, don't fail ... we just won't
661 * be as speedy as we might otherwise be.
662 */
663 for (i = 0; i < n; i++) {
664 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
665 if (!req)
666 return list_empty(head) ? -ENOMEM : 0;
667 req->complete = fn;
668 list_add_tail(&req->list, head);
669 if (allocated)
670 (*allocated)++;
671 }
672 return 0;
673}
674
675/**
676 * gs_start_io - start USB I/O streams
677 * @dev: encapsulates endpoints to use
678 * Context: holding port_lock; port_tty and port_usb are non-null
679 *
680 * We only start I/O when something is connected to both sides of
681 * this port. If nothing is listening on the host side, we may
682 * be pointlessly filling up our TX buffers and FIFO.
683 */
684static int gs_start_io(struct gs_port *port)
685{
686 struct list_head *head = &port->read_pool;
687 struct usb_ep *ep = port->port_usb->out;
688 int status;
689 unsigned started;
690
691 /* Allocate RX and TX I/O buffers. We can't easily do this much
692 * earlier (with GFP_KERNEL) because the requests are coupled to
693 * endpoints, as are the packet sizes we'll be using. Different
694 * configurations may use different endpoints with a given port;
695 * and high speed vs full speed changes packet sizes too.
696 */
697 status = gs_alloc_requests(ep, head, gs_read_complete,
698 &port->read_allocated);
699 if (status)
700 return status;
701
702 status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
703 gs_write_complete, &port->write_allocated);
704 if (status) {
705 gs_free_requests(ep, head, &port->read_allocated);
706 return status;
707 }
708
709 /* queue read requests */
710 port->n_read = 0;
711 started = gs_start_rx(port);
712
713 /* unblock any pending writes into our circular buffer */
714 if (started) {
715 tty_wakeup(port->port.tty);
716 } else {
717 gs_free_requests(ep, head, &port->read_allocated);
718 gs_free_requests(port->port_usb->in, &port->write_pool,
719 &port->write_allocated);
720 status = -EIO;
721 }
722
723 return status;
724}
725
726/*-------------------------------------------------------------------------*/
727
728/* TTY Driver */
729
730/*
731 * gs_open sets up the link between a gs_port and its associated TTY.
732 * That link is broken *only* by TTY close(), and all driver methods
733 * know that.
734 */
735static int gs_open(struct tty_struct *tty, struct file *file)
736{
737 int port_num = tty->index;
738 struct gs_port *port;
739 int status;
740
741 do {
742 mutex_lock(&ports[port_num].lock);
743 port = ports[port_num].port;
744 if (!port)
745 status = -ENODEV;
746 else {
747 spin_lock_irq(&port->port_lock);
748
749 /* already open? Great. */
750 if (port->port.count) {
751 status = 0;
752 port->port.count++;
753
754 /* currently opening/closing? wait ... */
755 } else if (port->openclose) {
756 status = -EBUSY;
757
758 /* ... else we do the work */
759 } else {
760 status = -EAGAIN;
761 port->openclose = true;
762 }
763 spin_unlock_irq(&port->port_lock);
764 }
765 mutex_unlock(&ports[port_num].lock);
766
767 switch (status) {
768 default:
769 /* fully handled */
770 return status;
771 case -EAGAIN:
772 /* must do the work */
773 break;
774 case -EBUSY:
775 /* wait for EAGAIN task to finish */
776 msleep(1);
777 /* REVISIT could have a waitchannel here, if
778 * concurrent open performance is important
779 */
780 break;
781 }
782 } while (status != -EAGAIN);
783
784 /* Do the "real open" */
785 spin_lock_irq(&port->port_lock);
786
787 /* allocate circular buffer on first open */
788 if (port->port_write_buf.buf_buf == NULL) {
789
790 spin_unlock_irq(&port->port_lock);
791 status = gs_buf_alloc(&port->port_write_buf, WRITE_BUF_SIZE);
792 spin_lock_irq(&port->port_lock);
793
794 if (status) {
795 pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
796 port->port_num, tty, file);
797 port->openclose = false;
798 goto exit_unlock_port;
799 }
800 }
801
802 /* REVISIT if REMOVED (ports[].port NULL), abort the open
803 * to let rmmod work faster (but this way isn't wrong).
804 */
805
806 /* REVISIT maybe wait for "carrier detect" */
807
808 tty->driver_data = port;
809 port->port.tty = tty;
810
811 port->port.count = 1;
812 port->openclose = false;
813
814 /* if connected, start the I/O stream */
815 if (port->port_usb) {
816 struct gserial *gser = port->port_usb;
817
818 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
819 gs_start_io(port);
820
821 if (gser->connect)
822 gser->connect(gser);
823 }
824
825 pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
826
827 status = 0;
828
829exit_unlock_port:
830 spin_unlock_irq(&port->port_lock);
831 return status;
832}
833
834static int gs_writes_finished(struct gs_port *p)
835{
836 int cond;
837
838 /* return true on disconnect or empty buffer */
839 spin_lock_irq(&p->port_lock);
840 cond = (p->port_usb == NULL) || !gs_buf_data_avail(&p->port_write_buf);
841 spin_unlock_irq(&p->port_lock);
842
843 return cond;
844}
845
846static void gs_close(struct tty_struct *tty, struct file *file)
847{
848 struct gs_port *port = tty->driver_data;
849 struct gserial *gser;
850
851 spin_lock_irq(&port->port_lock);
852
853 if (port->port.count != 1) {
854 if (port->port.count == 0)
855 WARN_ON(1);
856 else
857 --port->port.count;
858 goto exit;
859 }
860
861 pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
862
863 /* mark port as closing but in use; we can drop port lock
864 * and sleep if necessary
865 */
866 port->openclose = true;
867 port->port.count = 0;
868
869 gser = port->port_usb;
870 if (gser && gser->disconnect)
871 gser->disconnect(gser);
872
873 /* wait for circular write buffer to drain, disconnect, or at
874 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
875 */
876 if (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) {
877 spin_unlock_irq(&port->port_lock);
878 wait_event_interruptible_timeout(port->drain_wait,
879 gs_writes_finished(port),
880 GS_CLOSE_TIMEOUT * HZ);
881 spin_lock_irq(&port->port_lock);
882 gser = port->port_usb;
883 }
884
885 /* Iff we're disconnected, there can be no I/O in flight so it's
886 * ok to free the circular buffer; else just scrub it. And don't
887 * let the push tasklet fire again until we're re-opened.
888 */
889 if (gser == NULL)
890 gs_buf_free(&port->port_write_buf);
891 else
892 gs_buf_clear(&port->port_write_buf);
893
894 port->port.tty = NULL;
895
896 port->openclose = false;
897
898 pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
899 port->port_num, tty, file);
900
901 wake_up(&port->close_wait);
902exit:
903 spin_unlock_irq(&port->port_lock);
904}
905
906static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
907{
908 struct gs_port *port = tty->driver_data;
909 unsigned long flags;
910 int status;
911
912 pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
913 port->port_num, tty, count);
914
915 spin_lock_irqsave(&port->port_lock, flags);
916 if (count)
917 count = gs_buf_put(&port->port_write_buf, buf, count);
918 /* treat count == 0 as flush_chars() */
919 if (port->port_usb)
920 status = gs_start_tx(port);
921 spin_unlock_irqrestore(&port->port_lock, flags);
922
923 return count;
924}
925
926static int gs_put_char(struct tty_struct *tty, unsigned char ch)
927{
928 struct gs_port *port = tty->driver_data;
929 unsigned long flags;
930 int status;
931
932 pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
933 port->port_num, tty, ch, __builtin_return_address(0));
934
935 spin_lock_irqsave(&port->port_lock, flags);
936 status = gs_buf_put(&port->port_write_buf, &ch, 1);
937 spin_unlock_irqrestore(&port->port_lock, flags);
938
939 return status;
940}
941
942static void gs_flush_chars(struct tty_struct *tty)
943{
944 struct gs_port *port = tty->driver_data;
945 unsigned long flags;
946
947 pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
948
949 spin_lock_irqsave(&port->port_lock, flags);
950 if (port->port_usb)
951 gs_start_tx(port);
952 spin_unlock_irqrestore(&port->port_lock, flags);
953}
954
955static int gs_write_room(struct tty_struct *tty)
956{
957 struct gs_port *port = tty->driver_data;
958 unsigned long flags;
959 int room = 0;
960
961 spin_lock_irqsave(&port->port_lock, flags);
962 if (port->port_usb)
963 room = gs_buf_space_avail(&port->port_write_buf);
964 spin_unlock_irqrestore(&port->port_lock, flags);
965
966 pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
967 port->port_num, tty, room);
968
969 return room;
970}
971
972static int gs_chars_in_buffer(struct tty_struct *tty)
973{
974 struct gs_port *port = tty->driver_data;
975 unsigned long flags;
976 int chars = 0;
977
978 spin_lock_irqsave(&port->port_lock, flags);
979 chars = gs_buf_data_avail(&port->port_write_buf);
980 spin_unlock_irqrestore(&port->port_lock, flags);
981
982 pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
983 port->port_num, tty, chars);
984
985 return chars;
986}
987
988/* undo side effects of setting TTY_THROTTLED */
989static void gs_unthrottle(struct tty_struct *tty)
990{
991 struct gs_port *port = tty->driver_data;
992 unsigned long flags;
993
994 spin_lock_irqsave(&port->port_lock, flags);
995 if (port->port_usb) {
996 /* Kickstart read queue processing. We don't do xon/xoff,
997 * rts/cts, or other handshaking with the host, but if the
998 * read queue backs up enough we'll be NAKing OUT packets.
999 */
1000 tasklet_schedule(&port->push);
1001 pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
1002 }
1003 spin_unlock_irqrestore(&port->port_lock, flags);
1004}
1005
1006static int gs_break_ctl(struct tty_struct *tty, int duration)
1007{
1008 struct gs_port *port = tty->driver_data;
1009 int status = 0;
1010 struct gserial *gser;
1011
1012 pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
1013 port->port_num, duration);
1014
1015 spin_lock_irq(&port->port_lock);
1016 gser = port->port_usb;
1017 if (gser && gser->send_break)
1018 status = gser->send_break(gser, duration);
1019 spin_unlock_irq(&port->port_lock);
1020
1021 return status;
1022}
1023
1024static const struct tty_operations gs_tty_ops = {
1025 .open = gs_open,
1026 .close = gs_close,
1027 .write = gs_write,
1028 .put_char = gs_put_char,
1029 .flush_chars = gs_flush_chars,
1030 .write_room = gs_write_room,
1031 .chars_in_buffer = gs_chars_in_buffer,
1032 .unthrottle = gs_unthrottle,
1033 .break_ctl = gs_break_ctl,
1034};
1035
1036/*-------------------------------------------------------------------------*/
1037
1038static struct tty_driver *gs_tty_driver;
1039
1040#ifdef CONFIG_U_SERIAL_CONSOLE
1041
1042static struct gscons_info gscons_info;
1043static struct console gserial_cons;
1044
1045static struct usb_request *gs_request_new(struct usb_ep *ep)
1046{
1047 struct usb_request *req = usb_ep_alloc_request(ep, GFP_ATOMIC);
1048 if (!req)
1049 return NULL;
1050
1051 req->buf = kmalloc(ep->maxpacket, GFP_ATOMIC);
1052 if (!req->buf) {
1053 usb_ep_free_request(ep, req);
1054 return NULL;
1055 }
1056
1057 return req;
1058}
1059
1060static void gs_request_free(struct usb_request *req, struct usb_ep *ep)
1061{
1062 if (!req)
1063 return;
1064
1065 kfree(req->buf);
1066 usb_ep_free_request(ep, req);
1067}
1068
1069static void gs_complete_out(struct usb_ep *ep, struct usb_request *req)
1070{
1071 struct gscons_info *info = &gscons_info;
1072
1073 switch (req->status) {
1074 default:
1075 pr_warn("%s: unexpected %s status %d\n",
1076 __func__, ep->name, req->status);
1077 case 0:
1078 /* normal completion */
1079 spin_lock(&info->con_lock);
1080 info->req_busy = 0;
1081 spin_unlock(&info->con_lock);
1082
1083 wake_up_process(info->console_thread);
1084 break;
1085 case -ESHUTDOWN:
1086 /* disconnect */
1087 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
1088 break;
1089 }
1090}
1091
1092static int gs_console_connect(int port_num)
1093{
1094 struct gscons_info *info = &gscons_info;
1095 struct gs_port *port;
1096 struct usb_ep *ep;
1097
1098 if (port_num != gserial_cons.index) {
1099 pr_err("%s: port num [%d] is not support console\n",
1100 __func__, port_num);
1101 return -ENXIO;
1102 }
1103
1104 port = ports[port_num].port;
1105 ep = port->port_usb->in;
1106 if (!info->console_req) {
1107 info->console_req = gs_request_new(ep);
1108 if (!info->console_req)
1109 return -ENOMEM;
1110 info->console_req->complete = gs_complete_out;
1111 }
1112
1113 info->port = port;
1114 spin_lock(&info->con_lock);
1115 info->req_busy = 0;
1116 spin_unlock(&info->con_lock);
1117 pr_vdebug("port[%d] console connect!\n", port_num);
1118 return 0;
1119}
1120
1121static void gs_console_disconnect(struct usb_ep *ep)
1122{
1123 struct gscons_info *info = &gscons_info;
1124 struct usb_request *req = info->console_req;
1125
1126 gs_request_free(req, ep);
1127 info->console_req = NULL;
1128}
1129
1130static int gs_console_thread(void *data)
1131{
1132 struct gscons_info *info = &gscons_info;
1133 struct gs_port *port;
1134 struct usb_request *req;
1135 struct usb_ep *ep;
1136 int xfer, ret, count, size;
1137
1138 do {
1139 port = info->port;
1140 set_current_state(TASK_INTERRUPTIBLE);
1141 if (!port || !port->port_usb
1142 || !port->port_usb->in || !info->console_req)
1143 goto sched;
1144
1145 req = info->console_req;
1146 ep = port->port_usb->in;
1147
1148 spin_lock_irq(&info->con_lock);
1149 count = gs_buf_data_avail(&info->con_buf);
1150 size = ep->maxpacket;
1151
1152 if (count > 0 && !info->req_busy) {
1153 set_current_state(TASK_RUNNING);
1154 if (count < size)
1155 size = count;
1156
1157 xfer = gs_buf_get(&info->con_buf, req->buf, size);
1158 req->length = xfer;
1159
1160 spin_unlock(&info->con_lock);
1161 ret = usb_ep_queue(ep, req, GFP_ATOMIC);
1162 spin_lock(&info->con_lock);
1163 if (ret < 0)
1164 info->req_busy = 0;
1165 else
1166 info->req_busy = 1;
1167
1168 spin_unlock_irq(&info->con_lock);
1169 } else {
1170 spin_unlock_irq(&info->con_lock);
1171sched:
1172 if (kthread_should_stop()) {
1173 set_current_state(TASK_RUNNING);
1174 break;
1175 }
1176 schedule();
1177 }
1178 } while (1);
1179
1180 return 0;
1181}
1182
1183static int gs_console_setup(struct console *co, char *options)
1184{
1185 struct gscons_info *info = &gscons_info;
1186 int status;
1187
1188 info->port = NULL;
1189 info->console_req = NULL;
1190 info->req_busy = 0;
1191 spin_lock_init(&info->con_lock);
1192
1193 status = gs_buf_alloc(&info->con_buf, GS_CONSOLE_BUF_SIZE);
1194 if (status) {
1195 pr_err("%s: allocate console buffer failed\n", __func__);
1196 return status;
1197 }
1198
1199 info->console_thread = kthread_create(gs_console_thread,
1200 co, "gs_console");
1201 if (IS_ERR(info->console_thread)) {
1202 pr_err("%s: cannot create console thread\n", __func__);
1203 gs_buf_free(&info->con_buf);
1204 return PTR_ERR(info->console_thread);
1205 }
1206 wake_up_process(info->console_thread);
1207
1208 return 0;
1209}
1210
1211static void gs_console_write(struct console *co,
1212 const char *buf, unsigned count)
1213{
1214 struct gscons_info *info = &gscons_info;
1215 unsigned long flags;
1216
1217 spin_lock_irqsave(&info->con_lock, flags);
1218 gs_buf_put(&info->con_buf, buf, count);
1219 spin_unlock_irqrestore(&info->con_lock, flags);
1220
1221 wake_up_process(info->console_thread);
1222}
1223
1224static struct tty_driver *gs_console_device(struct console *co, int *index)
1225{
1226 struct tty_driver **p = (struct tty_driver **)co->data;
1227
1228 if (!*p)
1229 return NULL;
1230
1231 *index = co->index;
1232 return *p;
1233}
1234
1235static struct console gserial_cons = {
1236 .name = "ttyGS",
1237 .write = gs_console_write,
1238 .device = gs_console_device,
1239 .setup = gs_console_setup,
1240 .flags = CON_PRINTBUFFER,
1241 .index = -1,
1242 .data = &gs_tty_driver,
1243};
1244
1245static void gserial_console_init(void)
1246{
1247 register_console(&gserial_cons);
1248}
1249
1250static void gserial_console_exit(void)
1251{
1252 struct gscons_info *info = &gscons_info;
1253
1254 unregister_console(&gserial_cons);
1255 kthread_stop(info->console_thread);
1256 gs_buf_free(&info->con_buf);
1257}
1258
1259#else
1260
1261static int gs_console_connect(int port_num)
1262{
1263 return 0;
1264}
1265
1266static void gs_console_disconnect(struct usb_ep *ep)
1267{
1268}
1269
1270static void gserial_console_init(void)
1271{
1272}
1273
1274static void gserial_console_exit(void)
1275{
1276}
1277
1278#endif
1279
1280static int
1281gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1282{
1283 struct gs_port *port;
1284 int ret = 0;
1285
1286 mutex_lock(&ports[port_num].lock);
1287 if (ports[port_num].port) {
1288 ret = -EBUSY;
1289 goto out;
1290 }
1291
1292 port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1293 if (port == NULL) {
1294 ret = -ENOMEM;
1295 goto out;
1296 }
1297
1298 tty_port_init(&port->port);
1299 spin_lock_init(&port->port_lock);
1300 init_waitqueue_head(&port->drain_wait);
1301 init_waitqueue_head(&port->close_wait);
1302
1303 tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
1304
1305 INIT_LIST_HEAD(&port->read_pool);
1306 INIT_LIST_HEAD(&port->read_queue);
1307 INIT_LIST_HEAD(&port->write_pool);
1308
1309 port->port_num = port_num;
1310 port->port_line_coding = *coding;
1311
1312 ports[port_num].port = port;
1313out:
1314 mutex_unlock(&ports[port_num].lock);
1315 return ret;
1316}
1317
1318static int gs_closed(struct gs_port *port)
1319{
1320 int cond;
1321
1322 spin_lock_irq(&port->port_lock);
1323 cond = (port->port.count == 0) && !port->openclose;
1324 spin_unlock_irq(&port->port_lock);
1325 return cond;
1326}
1327
1328static void gserial_free_port(struct gs_port *port)
1329{
1330 tasklet_kill(&port->push);
1331 /* wait for old opens to finish */
1332 wait_event(port->close_wait, gs_closed(port));
1333 WARN_ON(port->port_usb != NULL);
1334 tty_port_destroy(&port->port);
1335 kfree(port);
1336}
1337
1338void gserial_free_line(unsigned char port_num)
1339{
1340 struct gs_port *port;
1341
1342 mutex_lock(&ports[port_num].lock);
1343 if (WARN_ON(!ports[port_num].port)) {
1344 mutex_unlock(&ports[port_num].lock);
1345 return;
1346 }
1347 port = ports[port_num].port;
1348 ports[port_num].port = NULL;
1349 mutex_unlock(&ports[port_num].lock);
1350
1351 gserial_free_port(port);
1352 tty_unregister_device(gs_tty_driver, port_num);
1353 gserial_console_exit();
1354}
1355EXPORT_SYMBOL_GPL(gserial_free_line);
1356
1357int gserial_alloc_line(unsigned char *line_num)
1358{
1359 struct usb_cdc_line_coding coding;
1360 struct device *tty_dev;
1361 int ret;
1362 int port_num;
1363
1364 coding.dwDTERate = cpu_to_le32(9600);
1365 coding.bCharFormat = 8;
1366 coding.bParityType = USB_CDC_NO_PARITY;
1367 coding.bDataBits = USB_CDC_1_STOP_BITS;
1368
1369 for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1370 ret = gs_port_alloc(port_num, &coding);
1371 if (ret == -EBUSY)
1372 continue;
1373 if (ret)
1374 return ret;
1375 break;
1376 }
1377 if (ret)
1378 return ret;
1379
1380 /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1381
1382 tty_dev = tty_port_register_device(&ports[port_num].port->port,
1383 gs_tty_driver, port_num, NULL);
1384 if (IS_ERR(tty_dev)) {
1385 struct gs_port *port;
1386 pr_err("%s: failed to register tty for port %d, err %ld\n",
1387 __func__, port_num, PTR_ERR(tty_dev));
1388
1389 ret = PTR_ERR(tty_dev);
1390 port = ports[port_num].port;
1391 ports[port_num].port = NULL;
1392 gserial_free_port(port);
1393 goto err;
1394 }
1395 *line_num = port_num;
1396 gserial_console_init();
1397err:
1398 return ret;
1399}
1400EXPORT_SYMBOL_GPL(gserial_alloc_line);
1401
1402/**
1403 * gserial_connect - notify TTY I/O glue that USB link is active
1404 * @gser: the function, set up with endpoints and descriptors
1405 * @port_num: which port is active
1406 * Context: any (usually from irq)
1407 *
1408 * This is called activate endpoints and let the TTY layer know that
1409 * the connection is active ... not unlike "carrier detect". It won't
1410 * necessarily start I/O queues; unless the TTY is held open by any
1411 * task, there would be no point. However, the endpoints will be
1412 * activated so the USB host can perform I/O, subject to basic USB
1413 * hardware flow control.
1414 *
1415 * Caller needs to have set up the endpoints and USB function in @dev
1416 * before calling this, as well as the appropriate (speed-specific)
1417 * endpoint descriptors, and also have allocate @port_num by calling
1418 * @gserial_alloc_line().
1419 *
1420 * Returns negative errno or zero.
1421 * On success, ep->driver_data will be overwritten.
1422 */
1423int gserial_connect(struct gserial *gser, u8 port_num)
1424{
1425 struct gs_port *port;
1426 unsigned long flags;
1427 int status;
1428
1429 if (port_num >= MAX_U_SERIAL_PORTS)
1430 return -ENXIO;
1431
1432 port = ports[port_num].port;
1433 if (!port) {
1434 pr_err("serial line %d not allocated.\n", port_num);
1435 return -EINVAL;
1436 }
1437 if (port->port_usb) {
1438 pr_err("serial line %d is in use.\n", port_num);
1439 return -EBUSY;
1440 }
1441
1442 /* activate the endpoints */
1443 status = usb_ep_enable(gser->in);
1444 if (status < 0)
1445 return status;
1446 gser->in->driver_data = port;
1447
1448 status = usb_ep_enable(gser->out);
1449 if (status < 0)
1450 goto fail_out;
1451 gser->out->driver_data = port;
1452
1453 /* then tell the tty glue that I/O can work */
1454 spin_lock_irqsave(&port->port_lock, flags);
1455 gser->ioport = port;
1456 port->port_usb = gser;
1457
1458 /* REVISIT unclear how best to handle this state...
1459 * we don't really couple it with the Linux TTY.
1460 */
1461 gser->port_line_coding = port->port_line_coding;
1462
1463 /* REVISIT if waiting on "carrier detect", signal. */
1464
1465 /* if it's already open, start I/O ... and notify the serial
1466 * protocol about open/close status (connect/disconnect).
1467 */
1468 if (port->port.count) {
1469 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1470 gs_start_io(port);
1471 if (gser->connect)
1472 gser->connect(gser);
1473 } else {
1474 if (gser->disconnect)
1475 gser->disconnect(gser);
1476 }
1477
1478 status = gs_console_connect(port_num);
1479 spin_unlock_irqrestore(&port->port_lock, flags);
1480
1481 return status;
1482
1483fail_out:
1484 usb_ep_disable(gser->in);
1485 return status;
1486}
1487EXPORT_SYMBOL_GPL(gserial_connect);
1488/**
1489 * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1490 * @gser: the function, on which gserial_connect() was called
1491 * Context: any (usually from irq)
1492 *
1493 * This is called to deactivate endpoints and let the TTY layer know
1494 * that the connection went inactive ... not unlike "hangup".
1495 *
1496 * On return, the state is as if gserial_connect() had never been called;
1497 * there is no active USB I/O on these endpoints.
1498 */
1499void gserial_disconnect(struct gserial *gser)
1500{
1501 struct gs_port *port = gser->ioport;
1502 unsigned long flags;
1503
1504 if (!port)
1505 return;
1506
1507 /* tell the TTY glue not to do I/O here any more */
1508 spin_lock_irqsave(&port->port_lock, flags);
1509
1510 /* REVISIT as above: how best to track this? */
1511 port->port_line_coding = gser->port_line_coding;
1512
1513 port->port_usb = NULL;
1514 gser->ioport = NULL;
1515 if (port->port.count > 0 || port->openclose) {
1516 wake_up_interruptible(&port->drain_wait);
1517 if (port->port.tty)
1518 tty_hangup(port->port.tty);
1519 }
1520 spin_unlock_irqrestore(&port->port_lock, flags);
1521
1522 /* disable endpoints, aborting down any active I/O */
1523 usb_ep_disable(gser->out);
1524 usb_ep_disable(gser->in);
1525
1526 /* finally, free any unused/unusable I/O buffers */
1527 spin_lock_irqsave(&port->port_lock, flags);
1528 if (port->port.count == 0 && !port->openclose)
1529 gs_buf_free(&port->port_write_buf);
1530 gs_free_requests(gser->out, &port->read_pool, NULL);
1531 gs_free_requests(gser->out, &port->read_queue, NULL);
1532 gs_free_requests(gser->in, &port->write_pool, NULL);
1533
1534 port->read_allocated = port->read_started =
1535 port->write_allocated = port->write_started = 0;
1536
1537 gs_console_disconnect(gser->in);
1538 spin_unlock_irqrestore(&port->port_lock, flags);
1539}
1540EXPORT_SYMBOL_GPL(gserial_disconnect);
1541
1542static int userial_init(void)
1543{
1544 unsigned i;
1545 int status;
1546
1547 gs_tty_driver = alloc_tty_driver(MAX_U_SERIAL_PORTS);
1548 if (!gs_tty_driver)
1549 return -ENOMEM;
1550
1551 gs_tty_driver->driver_name = "g_serial";
1552 gs_tty_driver->name = "ttyGS";
1553 /* uses dynamically assigned dev_t values */
1554
1555 gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
1556 gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
1557 gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
1558 gs_tty_driver->init_termios = tty_std_termios;
1559
1560 /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1561 * MS-Windows. Otherwise, most of these flags shouldn't affect
1562 * anything unless we were to actually hook up to a serial line.
1563 */
1564 gs_tty_driver->init_termios.c_cflag =
1565 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1566 gs_tty_driver->init_termios.c_ispeed = 9600;
1567 gs_tty_driver->init_termios.c_ospeed = 9600;
1568
1569 tty_set_operations(gs_tty_driver, &gs_tty_ops);
1570 for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1571 mutex_init(&ports[i].lock);
1572
1573 /* export the driver ... */
1574 status = tty_register_driver(gs_tty_driver);
1575 if (status) {
1576 pr_err("%s: cannot register, err %d\n",
1577 __func__, status);
1578 goto fail;
1579 }
1580
1581 pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1582 MAX_U_SERIAL_PORTS,
1583 (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1584
1585 return status;
1586fail:
1587 put_tty_driver(gs_tty_driver);
1588 gs_tty_driver = NULL;
1589 return status;
1590}
1591module_init(userial_init);
1592
1593static void userial_cleanup(void)
1594{
1595 tty_unregister_driver(gs_tty_driver);
1596 put_tty_driver(gs_tty_driver);
1597 gs_tty_driver = NULL;
1598}
1599module_exit(userial_cleanup);
1600
1601MODULE_LICENSE("GPL");