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