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