Linux 4.2.1
[linux/fpc-iii.git] / drivers / usb / gadget / function / u_serial.c
blob7ee057930ae71793bcbd2777cb275572af21c295
1 /*
2 * u_serial.c - utilities for USB gadget "serial port"/TTY support
4 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
5 * Copyright (C) 2008 David Brownell
6 * Copyright (C) 2008 by Nokia Corporation
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)
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.
18 /* #define VERBOSE_DEBUG */
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>
31 #include "u_serial.h"
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.
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.
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.
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.
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
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
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
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.
80 #define QUEUE_SIZE 16
81 #define WRITE_BUF_SIZE 8192 /* TX only */
83 /* circular buffer */
84 struct gs_buf {
85 unsigned buf_size;
86 char *buf_buf;
87 char *buf_get;
88 char *buf_put;
92 * The port structure holds info for each port, one for each minor number
93 * (and thus for each /dev/ node).
95 struct gs_port {
96 struct tty_port port;
97 spinlock_t port_lock; /* guard port_* access */
99 struct gserial *port_usb;
101 bool openclose; /* open/close in progress */
102 u8 port_num;
104 struct list_head read_pool;
105 int read_started;
106 int read_allocated;
107 struct list_head read_queue;
108 unsigned n_read;
109 struct tasklet_struct push;
111 struct list_head write_pool;
112 int write_started;
113 int write_allocated;
114 struct gs_buf port_write_buf;
115 wait_queue_head_t drain_wait; /* wait while writes drain */
116 bool write_busy;
118 /* REVISIT this state ... */
119 struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
122 static struct portmaster {
123 struct mutex lock; /* protect open/close */
124 struct gs_port *port;
125 } ports[MAX_U_SERIAL_PORTS];
127 #define GS_CLOSE_TIMEOUT 15 /* seconds */
131 #ifdef VERBOSE_DEBUG
132 #ifndef pr_vdebug
133 #define pr_vdebug(fmt, arg...) \
134 pr_debug(fmt, ##arg)
135 #endif /* pr_vdebug */
136 #else
137 #ifndef pr_vdebug
138 #define pr_vdebug(fmt, arg...) \
139 ({ if (0) pr_debug(fmt, ##arg); })
140 #endif /* pr_vdebug */
141 #endif
143 /*-------------------------------------------------------------------------*/
145 /* Circular Buffer */
148 * gs_buf_alloc
150 * Allocate a circular buffer and all associated memory.
152 static int gs_buf_alloc(struct gs_buf *gb, unsigned size)
154 gb->buf_buf = kmalloc(size, GFP_KERNEL);
155 if (gb->buf_buf == NULL)
156 return -ENOMEM;
158 gb->buf_size = size;
159 gb->buf_put = gb->buf_buf;
160 gb->buf_get = gb->buf_buf;
162 return 0;
166 * gs_buf_free
168 * Free the buffer and all associated memory.
170 static void gs_buf_free(struct gs_buf *gb)
172 kfree(gb->buf_buf);
173 gb->buf_buf = NULL;
177 * gs_buf_clear
179 * Clear out all data in the circular buffer.
181 static void gs_buf_clear(struct gs_buf *gb)
183 gb->buf_get = gb->buf_put;
184 /* equivalent to a get of all data available */
188 * gs_buf_data_avail
190 * Return the number of bytes of data written into the circular
191 * buffer.
193 static unsigned gs_buf_data_avail(struct gs_buf *gb)
195 return (gb->buf_size + gb->buf_put - gb->buf_get) % gb->buf_size;
199 * gs_buf_space_avail
201 * Return the number of bytes of space available in the circular
202 * buffer.
204 static unsigned gs_buf_space_avail(struct gs_buf *gb)
206 return (gb->buf_size + gb->buf_get - gb->buf_put - 1) % gb->buf_size;
210 * gs_buf_put
212 * Copy data data from a user buffer and put it into the circular buffer.
213 * Restrict to the amount of space available.
215 * Return the number of bytes copied.
217 static unsigned
218 gs_buf_put(struct gs_buf *gb, const char *buf, unsigned count)
220 unsigned len;
222 len = gs_buf_space_avail(gb);
223 if (count > len)
224 count = len;
226 if (count == 0)
227 return 0;
229 len = gb->buf_buf + gb->buf_size - gb->buf_put;
230 if (count > len) {
231 memcpy(gb->buf_put, buf, len);
232 memcpy(gb->buf_buf, buf+len, count - len);
233 gb->buf_put = gb->buf_buf + count - len;
234 } else {
235 memcpy(gb->buf_put, buf, count);
236 if (count < len)
237 gb->buf_put += count;
238 else /* count == len */
239 gb->buf_put = gb->buf_buf;
242 return count;
246 * gs_buf_get
248 * Get data from the circular buffer and copy to the given buffer.
249 * Restrict to the amount of data available.
251 * Return the number of bytes copied.
253 static unsigned
254 gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
256 unsigned len;
258 len = gs_buf_data_avail(gb);
259 if (count > len)
260 count = len;
262 if (count == 0)
263 return 0;
265 len = gb->buf_buf + gb->buf_size - gb->buf_get;
266 if (count > len) {
267 memcpy(buf, gb->buf_get, len);
268 memcpy(buf+len, gb->buf_buf, count - len);
269 gb->buf_get = gb->buf_buf + count - len;
270 } else {
271 memcpy(buf, gb->buf_get, count);
272 if (count < len)
273 gb->buf_get += count;
274 else /* count == len */
275 gb->buf_get = gb->buf_buf;
278 return count;
281 /*-------------------------------------------------------------------------*/
283 /* I/O glue between TTY (upper) and USB function (lower) driver layers */
286 * gs_alloc_req
288 * Allocate a usb_request and its buffer. Returns a pointer to the
289 * usb_request or NULL if there is an error.
291 struct usb_request *
292 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
294 struct usb_request *req;
296 req = usb_ep_alloc_request(ep, kmalloc_flags);
298 if (req != NULL) {
299 req->length = len;
300 req->buf = kmalloc(len, kmalloc_flags);
301 if (req->buf == NULL) {
302 usb_ep_free_request(ep, req);
303 return NULL;
307 return req;
309 EXPORT_SYMBOL_GPL(gs_alloc_req);
312 * gs_free_req
314 * Free a usb_request and its buffer.
316 void gs_free_req(struct usb_ep *ep, struct usb_request *req)
318 kfree(req->buf);
319 usb_ep_free_request(ep, req);
321 EXPORT_SYMBOL_GPL(gs_free_req);
324 * gs_send_packet
326 * If there is data to send, a packet is built in the given
327 * buffer and the size is returned. If there is no data to
328 * send, 0 is returned.
330 * Called with port_lock held.
332 static unsigned
333 gs_send_packet(struct gs_port *port, char *packet, unsigned size)
335 unsigned len;
337 len = gs_buf_data_avail(&port->port_write_buf);
338 if (len < size)
339 size = len;
340 if (size != 0)
341 size = gs_buf_get(&port->port_write_buf, packet, size);
342 return size;
346 * gs_start_tx
348 * This function finds available write requests, calls
349 * gs_send_packet to fill these packets with data, and
350 * continues until either there are no more write requests
351 * available or no more data to send. This function is
352 * run whenever data arrives or write requests are available.
354 * Context: caller owns port_lock; port_usb is non-null.
356 static int gs_start_tx(struct gs_port *port)
358 __releases(&port->port_lock)
359 __acquires(&port->port_lock)
362 struct list_head *pool = &port->write_pool;
363 struct usb_ep *in = port->port_usb->in;
364 int status = 0;
365 bool do_tty_wake = false;
367 while (!port->write_busy && !list_empty(pool)) {
368 struct usb_request *req;
369 int len;
371 if (port->write_started >= QUEUE_SIZE)
372 break;
374 req = list_entry(pool->next, struct usb_request, list);
375 len = gs_send_packet(port, req->buf, in->maxpacket);
376 if (len == 0) {
377 wake_up_interruptible(&port->drain_wait);
378 break;
380 do_tty_wake = true;
382 req->length = len;
383 list_del(&req->list);
384 req->zero = (gs_buf_data_avail(&port->port_write_buf) == 0);
386 pr_vdebug("ttyGS%d: tx len=%d, 0x%02x 0x%02x 0x%02x ...\n",
387 port->port_num, len, *((u8 *)req->buf),
388 *((u8 *)req->buf+1), *((u8 *)req->buf+2));
390 /* Drop lock while we call out of driver; completions
391 * could be issued while we do so. Disconnection may
392 * happen too; maybe immediately before we queue this!
394 * NOTE that we may keep sending data for a while after
395 * the TTY closed (dev->ioport->port_tty is NULL).
397 port->write_busy = true;
398 spin_unlock(&port->port_lock);
399 status = usb_ep_queue(in, req, GFP_ATOMIC);
400 spin_lock(&port->port_lock);
401 port->write_busy = false;
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;
410 port->write_started++;
412 /* abort immediately after disconnect */
413 if (!port->port_usb)
414 break;
417 if (do_tty_wake && port->port.tty)
418 tty_wakeup(port->port.tty);
419 return status;
423 * Context: caller owns port_lock, and port_usb is set
425 static unsigned gs_start_rx(struct gs_port *port)
427 __releases(&port->port_lock)
428 __acquires(&port->port_lock)
431 struct list_head *pool = &port->read_pool;
432 struct usb_ep *out = port->port_usb->out;
434 while (!list_empty(pool)) {
435 struct usb_request *req;
436 int status;
437 struct tty_struct *tty;
439 /* no more rx if closed */
440 tty = port->port.tty;
441 if (!tty)
442 break;
444 if (port->read_started >= QUEUE_SIZE)
445 break;
447 req = list_entry(pool->next, struct usb_request, list);
448 list_del(&req->list);
449 req->length = out->maxpacket;
451 /* drop lock while we call out; the controller driver
452 * may need to call us back (e.g. for disconnect)
454 spin_unlock(&port->port_lock);
455 status = usb_ep_queue(out, req, GFP_ATOMIC);
456 spin_lock(&port->port_lock);
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;
464 port->read_started++;
466 /* abort immediately after disconnect */
467 if (!port->port_usb)
468 break;
470 return port->read_started;
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.
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).
483 static void gs_rx_push(unsigned long _port)
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;
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;
497 req = list_first_entry(queue, struct usb_request, list);
499 /* leave data queued if tty was rx throttled */
500 if (tty && test_bit(TTY_THROTTLED, &tty->flags))
501 break;
503 switch (req->status) {
504 case -ESHUTDOWN:
505 disconnect = true;
506 pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
507 break;
509 default:
510 /* presumably a transient fault */
511 pr_warn("ttyGS%d: unexpected RX status %d\n",
512 port->port_num, req->status);
513 /* FALLTHROUGH */
514 case 0:
515 /* normal completion */
516 break;
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;
526 /* we may have pushed part of this packet already... */
527 n = port->n_read;
528 if (n) {
529 packet += n;
530 size -= n;
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("ttyGS%d: rx block %d/%d\n",
541 port->port_num, count, req->actual);
542 break;
544 port->n_read = 0;
547 list_move(&req->list, &port->read_pool);
548 port->read_started--;
551 /* Push from tty to ldisc; this is handled by a workqueue,
552 * so we won't get callbacks and can hold port_lock
554 if (do_push)
555 tty_flip_buffer_push(&port->port);
558 /* We want our data queue to become empty ASAP, keeping data
559 * in the tty and ldisc (not here). If we couldn't push any
560 * this time around, there may be trouble unless there's an
561 * implicit tty_unthrottle() call on its way...
563 * REVISIT we should probably add a timer to keep the tasklet
564 * from starving ... but it's not clear that case ever happens.
566 if (!list_empty(queue) && tty) {
567 if (!test_bit(TTY_THROTTLED, &tty->flags)) {
568 if (do_push)
569 tasklet_schedule(&port->push);
570 else
571 pr_warn("ttyGS%d: RX not scheduled?\n",
572 port->port_num);
576 /* If we're still connected, refill the USB RX queue. */
577 if (!disconnect && port->port_usb)
578 gs_start_rx(port);
580 spin_unlock_irq(&port->port_lock);
583 static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
585 struct gs_port *port = ep->driver_data;
587 /* Queue all received data until the tty layer is ready for it. */
588 spin_lock(&port->port_lock);
589 list_add_tail(&req->list, &port->read_queue);
590 tasklet_schedule(&port->push);
591 spin_unlock(&port->port_lock);
594 static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
596 struct gs_port *port = ep->driver_data;
598 spin_lock(&port->port_lock);
599 list_add(&req->list, &port->write_pool);
600 port->write_started--;
602 switch (req->status) {
603 default:
604 /* presumably a transient fault */
605 pr_warning("%s: unexpected %s status %d\n",
606 __func__, ep->name, req->status);
607 /* FALL THROUGH */
608 case 0:
609 /* normal completion */
610 gs_start_tx(port);
611 break;
613 case -ESHUTDOWN:
614 /* disconnect */
615 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
616 break;
619 spin_unlock(&port->port_lock);
622 static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
623 int *allocated)
625 struct usb_request *req;
627 while (!list_empty(head)) {
628 req = list_entry(head->next, struct usb_request, list);
629 list_del(&req->list);
630 gs_free_req(ep, req);
631 if (allocated)
632 (*allocated)--;
636 static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
637 void (*fn)(struct usb_ep *, struct usb_request *),
638 int *allocated)
640 int i;
641 struct usb_request *req;
642 int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
644 /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
645 * do quite that many this time, don't fail ... we just won't
646 * be as speedy as we might otherwise be.
648 for (i = 0; i < n; i++) {
649 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
650 if (!req)
651 return list_empty(head) ? -ENOMEM : 0;
652 req->complete = fn;
653 list_add_tail(&req->list, head);
654 if (allocated)
655 (*allocated)++;
657 return 0;
661 * gs_start_io - start USB I/O streams
662 * @dev: encapsulates endpoints to use
663 * Context: holding port_lock; port_tty and port_usb are non-null
665 * We only start I/O when something is connected to both sides of
666 * this port. If nothing is listening on the host side, we may
667 * be pointlessly filling up our TX buffers and FIFO.
669 static int gs_start_io(struct gs_port *port)
671 struct list_head *head = &port->read_pool;
672 struct usb_ep *ep = port->port_usb->out;
673 int status;
674 unsigned started;
676 /* Allocate RX and TX I/O buffers. We can't easily do this much
677 * earlier (with GFP_KERNEL) because the requests are coupled to
678 * endpoints, as are the packet sizes we'll be using. Different
679 * configurations may use different endpoints with a given port;
680 * and high speed vs full speed changes packet sizes too.
682 status = gs_alloc_requests(ep, head, gs_read_complete,
683 &port->read_allocated);
684 if (status)
685 return status;
687 status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
688 gs_write_complete, &port->write_allocated);
689 if (status) {
690 gs_free_requests(ep, head, &port->read_allocated);
691 return status;
694 /* queue read requests */
695 port->n_read = 0;
696 started = gs_start_rx(port);
698 /* unblock any pending writes into our circular buffer */
699 if (started) {
700 tty_wakeup(port->port.tty);
701 } else {
702 gs_free_requests(ep, head, &port->read_allocated);
703 gs_free_requests(port->port_usb->in, &port->write_pool,
704 &port->write_allocated);
705 status = -EIO;
708 return status;
711 /*-------------------------------------------------------------------------*/
713 /* TTY Driver */
716 * gs_open sets up the link between a gs_port and its associated TTY.
717 * That link is broken *only* by TTY close(), and all driver methods
718 * know that.
720 static int gs_open(struct tty_struct *tty, struct file *file)
722 int port_num = tty->index;
723 struct gs_port *port;
724 int status;
726 do {
727 mutex_lock(&ports[port_num].lock);
728 port = ports[port_num].port;
729 if (!port)
730 status = -ENODEV;
731 else {
732 spin_lock_irq(&port->port_lock);
734 /* already open? Great. */
735 if (port->port.count) {
736 status = 0;
737 port->port.count++;
739 /* currently opening/closing? wait ... */
740 } else if (port->openclose) {
741 status = -EBUSY;
743 /* ... else we do the work */
744 } else {
745 status = -EAGAIN;
746 port->openclose = true;
748 spin_unlock_irq(&port->port_lock);
750 mutex_unlock(&ports[port_num].lock);
752 switch (status) {
753 default:
754 /* fully handled */
755 return status;
756 case -EAGAIN:
757 /* must do the work */
758 break;
759 case -EBUSY:
760 /* wait for EAGAIN task to finish */
761 msleep(1);
762 /* REVISIT could have a waitchannel here, if
763 * concurrent open performance is important
765 break;
767 } while (status != -EAGAIN);
769 /* Do the "real open" */
770 spin_lock_irq(&port->port_lock);
772 /* allocate circular buffer on first open */
773 if (port->port_write_buf.buf_buf == NULL) {
775 spin_unlock_irq(&port->port_lock);
776 status = gs_buf_alloc(&port->port_write_buf, WRITE_BUF_SIZE);
777 spin_lock_irq(&port->port_lock);
779 if (status) {
780 pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
781 port->port_num, tty, file);
782 port->openclose = false;
783 goto exit_unlock_port;
787 /* REVISIT if REMOVED (ports[].port NULL), abort the open
788 * to let rmmod work faster (but this way isn't wrong).
791 /* REVISIT maybe wait for "carrier detect" */
793 tty->driver_data = port;
794 port->port.tty = tty;
796 port->port.count = 1;
797 port->openclose = false;
799 /* if connected, start the I/O stream */
800 if (port->port_usb) {
801 struct gserial *gser = port->port_usb;
803 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
804 gs_start_io(port);
806 if (gser->connect)
807 gser->connect(gser);
810 pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
812 status = 0;
814 exit_unlock_port:
815 spin_unlock_irq(&port->port_lock);
816 return status;
819 static int gs_writes_finished(struct gs_port *p)
821 int cond;
823 /* return true on disconnect or empty buffer */
824 spin_lock_irq(&p->port_lock);
825 cond = (p->port_usb == NULL) || !gs_buf_data_avail(&p->port_write_buf);
826 spin_unlock_irq(&p->port_lock);
828 return cond;
831 static void gs_close(struct tty_struct *tty, struct file *file)
833 struct gs_port *port = tty->driver_data;
834 struct gserial *gser;
836 spin_lock_irq(&port->port_lock);
838 if (port->port.count != 1) {
839 if (port->port.count == 0)
840 WARN_ON(1);
841 else
842 --port->port.count;
843 goto exit;
846 pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
848 /* mark port as closing but in use; we can drop port lock
849 * and sleep if necessary
851 port->openclose = true;
852 port->port.count = 0;
854 gser = port->port_usb;
855 if (gser && gser->disconnect)
856 gser->disconnect(gser);
858 /* wait for circular write buffer to drain, disconnect, or at
859 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
861 if (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) {
862 spin_unlock_irq(&port->port_lock);
863 wait_event_interruptible_timeout(port->drain_wait,
864 gs_writes_finished(port),
865 GS_CLOSE_TIMEOUT * HZ);
866 spin_lock_irq(&port->port_lock);
867 gser = port->port_usb;
870 /* Iff we're disconnected, there can be no I/O in flight so it's
871 * ok to free the circular buffer; else just scrub it. And don't
872 * let the push tasklet fire again until we're re-opened.
874 if (gser == NULL)
875 gs_buf_free(&port->port_write_buf);
876 else
877 gs_buf_clear(&port->port_write_buf);
879 tty->driver_data = NULL;
880 port->port.tty = NULL;
882 port->openclose = false;
884 pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
885 port->port_num, tty, file);
887 wake_up(&port->port.close_wait);
888 exit:
889 spin_unlock_irq(&port->port_lock);
892 static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
894 struct gs_port *port = tty->driver_data;
895 unsigned long flags;
896 int status;
898 pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
899 port->port_num, tty, count);
901 spin_lock_irqsave(&port->port_lock, flags);
902 if (count)
903 count = gs_buf_put(&port->port_write_buf, buf, count);
904 /* treat count == 0 as flush_chars() */
905 if (port->port_usb)
906 status = gs_start_tx(port);
907 spin_unlock_irqrestore(&port->port_lock, flags);
909 return count;
912 static int gs_put_char(struct tty_struct *tty, unsigned char ch)
914 struct gs_port *port = tty->driver_data;
915 unsigned long flags;
916 int status;
918 pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
919 port->port_num, tty, ch, __builtin_return_address(0));
921 spin_lock_irqsave(&port->port_lock, flags);
922 status = gs_buf_put(&port->port_write_buf, &ch, 1);
923 spin_unlock_irqrestore(&port->port_lock, flags);
925 return status;
928 static void gs_flush_chars(struct tty_struct *tty)
930 struct gs_port *port = tty->driver_data;
931 unsigned long flags;
933 pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
935 spin_lock_irqsave(&port->port_lock, flags);
936 if (port->port_usb)
937 gs_start_tx(port);
938 spin_unlock_irqrestore(&port->port_lock, flags);
941 static int gs_write_room(struct tty_struct *tty)
943 struct gs_port *port = tty->driver_data;
944 unsigned long flags;
945 int room = 0;
947 spin_lock_irqsave(&port->port_lock, flags);
948 if (port->port_usb)
949 room = gs_buf_space_avail(&port->port_write_buf);
950 spin_unlock_irqrestore(&port->port_lock, flags);
952 pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
953 port->port_num, tty, room);
955 return room;
958 static int gs_chars_in_buffer(struct tty_struct *tty)
960 struct gs_port *port = tty->driver_data;
961 unsigned long flags;
962 int chars = 0;
964 spin_lock_irqsave(&port->port_lock, flags);
965 chars = gs_buf_data_avail(&port->port_write_buf);
966 spin_unlock_irqrestore(&port->port_lock, flags);
968 pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
969 port->port_num, tty, chars);
971 return chars;
974 /* undo side effects of setting TTY_THROTTLED */
975 static void gs_unthrottle(struct tty_struct *tty)
977 struct gs_port *port = tty->driver_data;
978 unsigned long flags;
980 spin_lock_irqsave(&port->port_lock, flags);
981 if (port->port_usb) {
982 /* Kickstart read queue processing. We don't do xon/xoff,
983 * rts/cts, or other handshaking with the host, but if the
984 * read queue backs up enough we'll be NAKing OUT packets.
986 tasklet_schedule(&port->push);
987 pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
989 spin_unlock_irqrestore(&port->port_lock, flags);
992 static int gs_break_ctl(struct tty_struct *tty, int duration)
994 struct gs_port *port = tty->driver_data;
995 int status = 0;
996 struct gserial *gser;
998 pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
999 port->port_num, duration);
1001 spin_lock_irq(&port->port_lock);
1002 gser = port->port_usb;
1003 if (gser && gser->send_break)
1004 status = gser->send_break(gser, duration);
1005 spin_unlock_irq(&port->port_lock);
1007 return status;
1010 static const struct tty_operations gs_tty_ops = {
1011 .open = gs_open,
1012 .close = gs_close,
1013 .write = gs_write,
1014 .put_char = gs_put_char,
1015 .flush_chars = gs_flush_chars,
1016 .write_room = gs_write_room,
1017 .chars_in_buffer = gs_chars_in_buffer,
1018 .unthrottle = gs_unthrottle,
1019 .break_ctl = gs_break_ctl,
1022 /*-------------------------------------------------------------------------*/
1024 static struct tty_driver *gs_tty_driver;
1026 static int
1027 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1029 struct gs_port *port;
1030 int ret = 0;
1032 mutex_lock(&ports[port_num].lock);
1033 if (ports[port_num].port) {
1034 ret = -EBUSY;
1035 goto out;
1038 port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1039 if (port == NULL) {
1040 ret = -ENOMEM;
1041 goto out;
1044 tty_port_init(&port->port);
1045 spin_lock_init(&port->port_lock);
1046 init_waitqueue_head(&port->drain_wait);
1048 tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
1050 INIT_LIST_HEAD(&port->read_pool);
1051 INIT_LIST_HEAD(&port->read_queue);
1052 INIT_LIST_HEAD(&port->write_pool);
1054 port->port_num = port_num;
1055 port->port_line_coding = *coding;
1057 ports[port_num].port = port;
1058 out:
1059 mutex_unlock(&ports[port_num].lock);
1060 return ret;
1063 static int gs_closed(struct gs_port *port)
1065 int cond;
1067 spin_lock_irq(&port->port_lock);
1068 cond = (port->port.count == 0) && !port->openclose;
1069 spin_unlock_irq(&port->port_lock);
1070 return cond;
1073 static void gserial_free_port(struct gs_port *port)
1075 tasklet_kill(&port->push);
1076 /* wait for old opens to finish */
1077 wait_event(port->port.close_wait, gs_closed(port));
1078 WARN_ON(port->port_usb != NULL);
1079 tty_port_destroy(&port->port);
1080 kfree(port);
1083 void gserial_free_line(unsigned char port_num)
1085 struct gs_port *port;
1087 mutex_lock(&ports[port_num].lock);
1088 if (WARN_ON(!ports[port_num].port)) {
1089 mutex_unlock(&ports[port_num].lock);
1090 return;
1092 port = ports[port_num].port;
1093 ports[port_num].port = NULL;
1094 mutex_unlock(&ports[port_num].lock);
1096 gserial_free_port(port);
1097 tty_unregister_device(gs_tty_driver, port_num);
1099 EXPORT_SYMBOL_GPL(gserial_free_line);
1101 int gserial_alloc_line(unsigned char *line_num)
1103 struct usb_cdc_line_coding coding;
1104 struct device *tty_dev;
1105 int ret;
1106 int port_num;
1108 coding.dwDTERate = cpu_to_le32(9600);
1109 coding.bCharFormat = 8;
1110 coding.bParityType = USB_CDC_NO_PARITY;
1111 coding.bDataBits = USB_CDC_1_STOP_BITS;
1113 for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1114 ret = gs_port_alloc(port_num, &coding);
1115 if (ret == -EBUSY)
1116 continue;
1117 if (ret)
1118 return ret;
1119 break;
1121 if (ret)
1122 return ret;
1124 /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1126 tty_dev = tty_port_register_device(&ports[port_num].port->port,
1127 gs_tty_driver, port_num, NULL);
1128 if (IS_ERR(tty_dev)) {
1129 struct gs_port *port;
1130 pr_err("%s: failed to register tty for port %d, err %ld\n",
1131 __func__, port_num, PTR_ERR(tty_dev));
1133 ret = PTR_ERR(tty_dev);
1134 port = ports[port_num].port;
1135 ports[port_num].port = NULL;
1136 gserial_free_port(port);
1137 goto err;
1139 *line_num = port_num;
1140 err:
1141 return ret;
1143 EXPORT_SYMBOL_GPL(gserial_alloc_line);
1146 * gserial_connect - notify TTY I/O glue that USB link is active
1147 * @gser: the function, set up with endpoints and descriptors
1148 * @port_num: which port is active
1149 * Context: any (usually from irq)
1151 * This is called activate endpoints and let the TTY layer know that
1152 * the connection is active ... not unlike "carrier detect". It won't
1153 * necessarily start I/O queues; unless the TTY is held open by any
1154 * task, there would be no point. However, the endpoints will be
1155 * activated so the USB host can perform I/O, subject to basic USB
1156 * hardware flow control.
1158 * Caller needs to have set up the endpoints and USB function in @dev
1159 * before calling this, as well as the appropriate (speed-specific)
1160 * endpoint descriptors, and also have allocate @port_num by calling
1161 * @gserial_alloc_line().
1163 * Returns negative errno or zero.
1164 * On success, ep->driver_data will be overwritten.
1166 int gserial_connect(struct gserial *gser, u8 port_num)
1168 struct gs_port *port;
1169 unsigned long flags;
1170 int status;
1172 if (port_num >= MAX_U_SERIAL_PORTS)
1173 return -ENXIO;
1175 port = ports[port_num].port;
1176 if (!port) {
1177 pr_err("serial line %d not allocated.\n", port_num);
1178 return -EINVAL;
1180 if (port->port_usb) {
1181 pr_err("serial line %d is in use.\n", port_num);
1182 return -EBUSY;
1185 /* activate the endpoints */
1186 status = usb_ep_enable(gser->in);
1187 if (status < 0)
1188 return status;
1189 gser->in->driver_data = port;
1191 status = usb_ep_enable(gser->out);
1192 if (status < 0)
1193 goto fail_out;
1194 gser->out->driver_data = port;
1196 /* then tell the tty glue that I/O can work */
1197 spin_lock_irqsave(&port->port_lock, flags);
1198 gser->ioport = port;
1199 port->port_usb = gser;
1201 /* REVISIT unclear how best to handle this state...
1202 * we don't really couple it with the Linux TTY.
1204 gser->port_line_coding = port->port_line_coding;
1206 /* REVISIT if waiting on "carrier detect", signal. */
1208 /* if it's already open, start I/O ... and notify the serial
1209 * protocol about open/close status (connect/disconnect).
1211 if (port->port.count) {
1212 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1213 gs_start_io(port);
1214 if (gser->connect)
1215 gser->connect(gser);
1216 } else {
1217 if (gser->disconnect)
1218 gser->disconnect(gser);
1221 spin_unlock_irqrestore(&port->port_lock, flags);
1223 return status;
1225 fail_out:
1226 usb_ep_disable(gser->in);
1227 gser->in->driver_data = NULL;
1228 return status;
1230 EXPORT_SYMBOL_GPL(gserial_connect);
1232 * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1233 * @gser: the function, on which gserial_connect() was called
1234 * Context: any (usually from irq)
1236 * This is called to deactivate endpoints and let the TTY layer know
1237 * that the connection went inactive ... not unlike "hangup".
1239 * On return, the state is as if gserial_connect() had never been called;
1240 * there is no active USB I/O on these endpoints.
1242 void gserial_disconnect(struct gserial *gser)
1244 struct gs_port *port = gser->ioport;
1245 unsigned long flags;
1247 if (!port)
1248 return;
1250 /* tell the TTY glue not to do I/O here any more */
1251 spin_lock_irqsave(&port->port_lock, flags);
1253 /* REVISIT as above: how best to track this? */
1254 port->port_line_coding = gser->port_line_coding;
1256 port->port_usb = NULL;
1257 gser->ioport = NULL;
1258 if (port->port.count > 0 || port->openclose) {
1259 wake_up_interruptible(&port->drain_wait);
1260 if (port->port.tty)
1261 tty_hangup(port->port.tty);
1263 spin_unlock_irqrestore(&port->port_lock, flags);
1265 /* disable endpoints, aborting down any active I/O */
1266 usb_ep_disable(gser->out);
1267 gser->out->driver_data = NULL;
1269 usb_ep_disable(gser->in);
1270 gser->in->driver_data = NULL;
1272 /* finally, free any unused/unusable I/O buffers */
1273 spin_lock_irqsave(&port->port_lock, flags);
1274 if (port->port.count == 0 && !port->openclose)
1275 gs_buf_free(&port->port_write_buf);
1276 gs_free_requests(gser->out, &port->read_pool, NULL);
1277 gs_free_requests(gser->out, &port->read_queue, NULL);
1278 gs_free_requests(gser->in, &port->write_pool, NULL);
1280 port->read_allocated = port->read_started =
1281 port->write_allocated = port->write_started = 0;
1283 spin_unlock_irqrestore(&port->port_lock, flags);
1285 EXPORT_SYMBOL_GPL(gserial_disconnect);
1287 static int userial_init(void)
1289 unsigned i;
1290 int status;
1292 gs_tty_driver = alloc_tty_driver(MAX_U_SERIAL_PORTS);
1293 if (!gs_tty_driver)
1294 return -ENOMEM;
1296 gs_tty_driver->driver_name = "g_serial";
1297 gs_tty_driver->name = "ttyGS";
1298 /* uses dynamically assigned dev_t values */
1300 gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
1301 gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
1302 gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
1303 gs_tty_driver->init_termios = tty_std_termios;
1305 /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1306 * MS-Windows. Otherwise, most of these flags shouldn't affect
1307 * anything unless we were to actually hook up to a serial line.
1309 gs_tty_driver->init_termios.c_cflag =
1310 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1311 gs_tty_driver->init_termios.c_ispeed = 9600;
1312 gs_tty_driver->init_termios.c_ospeed = 9600;
1314 tty_set_operations(gs_tty_driver, &gs_tty_ops);
1315 for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1316 mutex_init(&ports[i].lock);
1318 /* export the driver ... */
1319 status = tty_register_driver(gs_tty_driver);
1320 if (status) {
1321 pr_err("%s: cannot register, err %d\n",
1322 __func__, status);
1323 goto fail;
1326 pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1327 MAX_U_SERIAL_PORTS,
1328 (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1330 return status;
1331 fail:
1332 put_tty_driver(gs_tty_driver);
1333 gs_tty_driver = NULL;
1334 return status;
1336 module_init(userial_init);
1338 static void userial_cleanup(void)
1340 tty_unregister_driver(gs_tty_driver);
1341 put_tty_driver(gs_tty_driver);
1342 gs_tty_driver = NULL;
1344 module_exit(userial_cleanup);
1346 MODULE_LICENSE("GPL");