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