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