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