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