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>
34 * This component encapsulates the TTY layer glue needed to provide basic
35 * "serial port" functionality through the USB gadget stack. Each such
36 * port is exposed through a /dev/ttyGS* node.
38 * After initialization (gserial_setup), these TTY port devices stay
39 * available until they are removed (gserial_cleanup). Each one may be
40 * connected to a USB function (gserial_connect), or disconnected (with
41 * gserial_disconnect) when the USB host issues a config change event.
42 * Data can only flow when the port is connected to the host.
44 * A given TTY port can be made available in multiple configurations.
45 * For example, each one might expose a ttyGS0 node which provides a
46 * login application. In one case that might use CDC ACM interface 0,
47 * while another configuration might use interface 3 for that. The
48 * work to handle that (including descriptor management) is not part
51 * Configurations may expose more than one TTY port. For example, if
52 * ttyGS0 provides login service, then ttyGS1 might provide dialer access
53 * for a telephone or fax link. And ttyGS2 might be something that just
54 * needs a simple byte stream interface for some messaging protocol that
55 * is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
58 #define PREFIX "ttyGS"
61 * gserial is the lifecycle interface, used by USB functions
62 * gs_port is the I/O nexus, used by the tty driver
63 * tty_struct links to the tty/filesystem framework
65 * gserial <---> gs_port ... links will be null when the USB link is
66 * inactive; managed by gserial_{connect,disconnect}(). each gserial
67 * instance can wrap its own USB control protocol.
68 * gserial->ioport == usb_ep->driver_data ... gs_port
69 * gs_port->port_usb ... gserial
71 * gs_port <---> tty_struct ... links will be null when the TTY file
72 * isn't opened; managed by gs_open()/gs_close()
73 * gserial->port_tty ... tty_struct
74 * tty_struct->driver_data ... gserial
77 /* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
78 * next layer of buffering. For TX that's a circular buffer; for RX
79 * consider it a NOP. A third layer is provided by the TTY code.
82 #define WRITE_BUF_SIZE 8192 /* TX only */
93 * The port structure holds info for each port, one for each minor number
94 * (and thus for each /dev/ node).
98 spinlock_t port_lock; /* guard port_* access */
100 struct gserial *port_usb;
102 bool openclose; /* open/close in progress */
105 struct list_head read_pool;
108 struct list_head read_queue;
110 struct tasklet_struct push;
112 struct list_head write_pool;
115 struct gs_buf port_write_buf;
116 wait_queue_head_t drain_wait; /* wait while writes drain */
118 /* REVISIT this state ... */
119 struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
122 /* increase N_PORTS if you need more */
124 static struct portmaster {
125 struct mutex lock; /* protect open/close */
126 struct gs_port *port;
128 static unsigned n_ports;
130 #define GS_CLOSE_TIMEOUT 15 /* seconds */
136 #define pr_vdebug(fmt, arg...) \
138 #endif /* pr_vdebug */
141 #define pr_vdebug(fmt, arg...) \
142 ({ if (0) pr_debug(fmt, ##arg); })
143 #endif /* pr_vdebug */
146 /*-------------------------------------------------------------------------*/
148 /* Circular Buffer */
153 * Allocate a circular buffer and all associated memory.
155 static int gs_buf_alloc(struct gs_buf *gb, unsigned size)
157 gb->buf_buf = kmalloc(size, GFP_KERNEL);
158 if (gb->buf_buf == NULL)
162 gb->buf_put = gb->buf_buf;
163 gb->buf_get = gb->buf_buf;
171 * Free the buffer and all associated memory.
173 static void gs_buf_free(struct gs_buf *gb)
182 * Clear out all data in the circular buffer.
184 static void gs_buf_clear(struct gs_buf *gb)
186 gb->buf_get = gb->buf_put;
187 /* equivalent to a get of all data available */
193 * Return the number of bytes of data written into the circular
196 static unsigned gs_buf_data_avail(struct gs_buf *gb)
198 return (gb->buf_size + gb->buf_put - gb->buf_get) % gb->buf_size;
204 * Return the number of bytes of space available in the circular
207 static unsigned gs_buf_space_avail(struct gs_buf *gb)
209 return (gb->buf_size + gb->buf_get - gb->buf_put - 1) % gb->buf_size;
215 * Copy data data from a user buffer and put it into the circular buffer.
216 * Restrict to the amount of space available.
218 * Return the number of bytes copied.
221 gs_buf_put(struct gs_buf *gb, const char *buf, unsigned count)
225 len = gs_buf_space_avail(gb);
232 len = gb->buf_buf + gb->buf_size - gb->buf_put;
234 memcpy(gb->buf_put, buf, len);
235 memcpy(gb->buf_buf, buf+len, count - len);
236 gb->buf_put = gb->buf_buf + count - len;
238 memcpy(gb->buf_put, buf, count);
240 gb->buf_put += count;
241 else /* count == len */
242 gb->buf_put = gb->buf_buf;
251 * Get data from the circular buffer and copy to the given buffer.
252 * Restrict to the amount of data available.
254 * Return the number of bytes copied.
257 gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
261 len = gs_buf_data_avail(gb);
268 len = gb->buf_buf + gb->buf_size - gb->buf_get;
270 memcpy(buf, gb->buf_get, len);
271 memcpy(buf+len, gb->buf_buf, count - len);
272 gb->buf_get = gb->buf_buf + count - len;
274 memcpy(buf, gb->buf_get, count);
276 gb->buf_get += count;
277 else /* count == len */
278 gb->buf_get = gb->buf_buf;
284 /*-------------------------------------------------------------------------*/
286 /* I/O glue between TTY (upper) and USB function (lower) driver layers */
291 * Allocate a usb_request and its buffer. Returns a pointer to the
292 * usb_request or NULL if there is an error.
295 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
297 struct usb_request *req;
299 req = usb_ep_alloc_request(ep, kmalloc_flags);
303 req->buf = kmalloc(len, kmalloc_flags);
304 if (req->buf == NULL) {
305 usb_ep_free_request(ep, req);
316 * Free a usb_request and its buffer.
318 void gs_free_req(struct usb_ep *ep, struct usb_request *req)
321 usb_ep_free_request(ep, req);
327 * If there is data to send, a packet is built in the given
328 * buffer and the size is returned. If there is no data to
329 * send, 0 is returned.
331 * Called with port_lock held.
334 gs_send_packet(struct gs_port *port, char *packet, unsigned size)
338 len = gs_buf_data_avail(&port->port_write_buf);
342 size = gs_buf_get(&port->port_write_buf, packet, size);
349 * This function finds available write requests, calls
350 * gs_send_packet to fill these packets with data, and
351 * continues until either there are no more write requests
352 * available or no more data to send. This function is
353 * run whenever data arrives or write requests are available.
355 * Context: caller owns port_lock; port_usb is non-null.
357 static int gs_start_tx(struct gs_port *port)
359 __releases(&port->port_lock)
360 __acquires(&port->port_lock)
363 struct list_head *pool = &port->write_pool;
364 struct usb_ep *in = port->port_usb->in;
366 bool do_tty_wake = false;
368 while (!list_empty(pool)) {
369 struct usb_request *req;
372 if (port->write_started >= QUEUE_SIZE)
375 req = list_entry(pool->next, struct usb_request, list);
376 len = gs_send_packet(port, req->buf, in->maxpacket);
378 wake_up_interruptible(&port->drain_wait);
384 list_del(&req->list);
385 req->zero = (gs_buf_data_avail(&port->port_write_buf) == 0);
387 pr_vdebug(PREFIX "%d: tx len=%d, 0x%02x 0x%02x 0x%02x ...\n",
388 port->port_num, len, *((u8 *)req->buf),
389 *((u8 *)req->buf+1), *((u8 *)req->buf+2));
391 /* Drop lock while we call out of driver; completions
392 * could be issued while we do so. Disconnection may
393 * happen too; maybe immediately before we queue this!
395 * NOTE that we may keep sending data for a while after
396 * the TTY closed (dev->ioport->port_tty is NULL).
398 spin_unlock(&port->port_lock);
399 status = usb_ep_queue(in, req, GFP_ATOMIC);
400 spin_lock(&port->port_lock);
403 pr_debug("%s: %s %s err %d\n",
404 __func__, "queue", in->name, status);
405 list_add(&req->list, pool);
409 port->write_started++;
411 /* abort immediately after disconnect */
416 if (do_tty_wake && port->port.tty)
417 tty_wakeup(port->port.tty);
422 * Context: caller owns port_lock, and port_usb is set
424 static unsigned gs_start_rx(struct gs_port *port)
426 __releases(&port->port_lock)
427 __acquires(&port->port_lock)
430 struct list_head *pool = &port->read_pool;
431 struct usb_ep *out = port->port_usb->out;
433 while (!list_empty(pool)) {
434 struct usb_request *req;
436 struct tty_struct *tty;
438 /* no more rx if closed */
439 tty = port->port.tty;
443 if (port->read_started >= QUEUE_SIZE)
446 req = list_entry(pool->next, struct usb_request, list);
447 list_del(&req->list);
448 req->length = out->maxpacket;
450 /* drop lock while we call out; the controller driver
451 * may need to call us back (e.g. for disconnect)
453 spin_unlock(&port->port_lock);
454 status = usb_ep_queue(out, req, GFP_ATOMIC);
455 spin_lock(&port->port_lock);
458 pr_debug("%s: %s %s err %d\n",
459 __func__, "queue", out->name, status);
460 list_add(&req->list, pool);
463 port->read_started++;
465 /* abort immediately after disconnect */
469 return port->read_started;
473 * RX tasklet takes data out of the RX queue and hands it up to the TTY
474 * layer until it refuses to take any more data (or is throttled back).
475 * Then it issues reads for any further data.
477 * If the RX queue becomes full enough that no usb_request is queued,
478 * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
479 * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
480 * can be buffered before the TTY layer's buffers (currently 64 KB).
482 static void gs_rx_push(unsigned long _port)
484 struct gs_port *port = (void *)_port;
485 struct tty_struct *tty;
486 struct list_head *queue = &port->read_queue;
487 bool disconnect = false;
488 bool do_push = false;
490 /* hand any queued data to the tty */
491 spin_lock_irq(&port->port_lock);
492 tty = port->port.tty;
493 while (!list_empty(queue)) {
494 struct usb_request *req;
496 req = list_first_entry(queue, struct usb_request, list);
498 /* discard data if tty was closed */
502 /* leave data queued if tty was rx throttled */
503 if (test_bit(TTY_THROTTLED, &tty->flags))
506 switch (req->status) {
509 pr_vdebug(PREFIX "%d: shutdown\n", port->port_num);
513 /* presumably a transient fault */
514 pr_warning(PREFIX "%d: unexpected RX status %d\n",
515 port->port_num, req->status);
518 /* normal completion */
522 /* push data to (open) tty */
524 char *packet = req->buf;
525 unsigned size = req->actual;
529 /* we may have pushed part of this packet already... */
536 count = tty_insert_flip_string(tty, packet, size);
540 /* stop pushing; TTY layer can't handle more */
541 port->n_read += count;
542 pr_vdebug(PREFIX "%d: rx block %d/%d\n",
550 list_move(&req->list, &port->read_pool);
551 port->read_started--;
554 /* Push from tty to ldisc; without low_latency set this is handled by
555 * a workqueue, so we won't get callbacks and can hold port_lock
558 tty_flip_buffer_push(tty);
561 /* We want our data queue to become empty ASAP, keeping data
562 * in the tty and ldisc (not here). If we couldn't push any
563 * this time around, there may be trouble unless there's an
564 * implicit tty_unthrottle() call on its way...
566 * REVISIT we should probably add a timer to keep the tasklet
567 * from starving ... but it's not clear that case ever happens.
569 if (!list_empty(queue) && tty) {
570 if (!test_bit(TTY_THROTTLED, &tty->flags)) {
572 tasklet_schedule(&port->push);
574 pr_warning(PREFIX "%d: RX not scheduled?\n",
579 /* If we're still connected, refill the USB RX queue. */
580 if (!disconnect && port->port_usb)
583 spin_unlock_irq(&port->port_lock);
586 static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
588 struct gs_port *port = ep->driver_data;
590 /* Queue all received data until the tty layer is ready for it. */
591 spin_lock(&port->port_lock);
592 list_add_tail(&req->list, &port->read_queue);
593 tasklet_schedule(&port->push);
594 spin_unlock(&port->port_lock);
597 static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
599 struct gs_port *port = ep->driver_data;
601 spin_lock(&port->port_lock);
602 list_add(&req->list, &port->write_pool);
603 port->write_started--;
605 switch (req->status) {
607 /* presumably a transient fault */
608 pr_warning("%s: unexpected %s status %d\n",
609 __func__, ep->name, req->status);
612 /* normal completion */
618 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
622 spin_unlock(&port->port_lock);
625 static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
628 struct usb_request *req;
630 while (!list_empty(head)) {
631 req = list_entry(head->next, struct usb_request, list);
632 list_del(&req->list);
633 gs_free_req(ep, req);
639 static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
640 void (*fn)(struct usb_ep *, struct usb_request *),
644 struct usb_request *req;
645 int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
647 /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
648 * do quite that many this time, don't fail ... we just won't
649 * be as speedy as we might otherwise be.
651 for (i = 0; i < n; i++) {
652 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
654 return list_empty(head) ? -ENOMEM : 0;
656 list_add_tail(&req->list, head);
664 * gs_start_io - start USB I/O streams
665 * @dev: encapsulates endpoints to use
666 * Context: holding port_lock; port_tty and port_usb are non-null
668 * We only start I/O when something is connected to both sides of
669 * this port. If nothing is listening on the host side, we may
670 * be pointlessly filling up our TX buffers and FIFO.
672 static int gs_start_io(struct gs_port *port)
674 struct list_head *head = &port->read_pool;
675 struct usb_ep *ep = port->port_usb->out;
679 /* Allocate RX and TX I/O buffers. We can't easily do this much
680 * earlier (with GFP_KERNEL) because the requests are coupled to
681 * endpoints, as are the packet sizes we'll be using. Different
682 * configurations may use different endpoints with a given port;
683 * and high speed vs full speed changes packet sizes too.
685 status = gs_alloc_requests(ep, head, gs_read_complete,
686 &port->read_allocated);
690 status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
691 gs_write_complete, &port->write_allocated);
693 gs_free_requests(ep, head, &port->read_allocated);
697 /* queue read requests */
699 started = gs_start_rx(port);
701 /* unblock any pending writes into our circular buffer */
703 tty_wakeup(port->port.tty);
705 gs_free_requests(ep, head, &port->read_allocated);
706 gs_free_requests(port->port_usb->in, &port->write_pool,
707 &port->write_allocated);
714 /*-------------------------------------------------------------------------*/
719 * gs_open sets up the link between a gs_port and its associated TTY.
720 * That link is broken *only* by TTY close(), and all driver methods
723 static int gs_open(struct tty_struct *tty, struct file *file)
725 int port_num = tty->index;
726 struct gs_port *port;
730 mutex_lock(&ports[port_num].lock);
731 port = ports[port_num].port;
735 spin_lock_irq(&port->port_lock);
737 /* already open? Great. */
738 if (port->port.count) {
742 /* currently opening/closing? wait ... */
743 } else if (port->openclose) {
746 /* ... else we do the work */
749 port->openclose = true;
751 spin_unlock_irq(&port->port_lock);
753 mutex_unlock(&ports[port_num].lock);
760 /* must do the work */
763 /* wait for EAGAIN task to finish */
765 /* REVISIT could have a waitchannel here, if
766 * concurrent open performance is important
770 } while (status != -EAGAIN);
772 /* Do the "real open" */
773 spin_lock_irq(&port->port_lock);
775 /* allocate circular buffer on first open */
776 if (port->port_write_buf.buf_buf == NULL) {
778 spin_unlock_irq(&port->port_lock);
779 status = gs_buf_alloc(&port->port_write_buf, WRITE_BUF_SIZE);
780 spin_lock_irq(&port->port_lock);
783 pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
784 port->port_num, tty, file);
785 port->openclose = false;
786 goto exit_unlock_port;
790 /* REVISIT if REMOVED (ports[].port NULL), abort the open
791 * to let rmmod work faster (but this way isn't wrong).
794 /* REVISIT maybe wait for "carrier detect" */
796 tty->driver_data = port;
797 port->port.tty = tty;
799 port->port.count = 1;
800 port->openclose = false;
802 /* if connected, start the I/O stream */
803 if (port->port_usb) {
804 struct gserial *gser = port->port_usb;
806 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
813 pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
818 spin_unlock_irq(&port->port_lock);
822 static int gs_writes_finished(struct gs_port *p)
826 /* return true on disconnect or empty buffer */
827 spin_lock_irq(&p->port_lock);
828 cond = (p->port_usb == NULL) || !gs_buf_data_avail(&p->port_write_buf);
829 spin_unlock_irq(&p->port_lock);
834 static void gs_close(struct tty_struct *tty, struct file *file)
836 struct gs_port *port = tty->driver_data;
837 struct gserial *gser;
839 spin_lock_irq(&port->port_lock);
841 if (port->port.count != 1) {
842 if (port->port.count == 0)
849 pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
851 /* mark port as closing but in use; we can drop port lock
852 * and sleep if necessary
854 port->openclose = true;
855 port->port.count = 0;
857 gser = port->port_usb;
858 if (gser && gser->disconnect)
859 gser->disconnect(gser);
861 /* wait for circular write buffer to drain, disconnect, or at
862 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
864 if (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) {
865 spin_unlock_irq(&port->port_lock);
866 wait_event_interruptible_timeout(port->drain_wait,
867 gs_writes_finished(port),
868 GS_CLOSE_TIMEOUT * HZ);
869 spin_lock_irq(&port->port_lock);
870 gser = port->port_usb;
873 /* Iff we're disconnected, there can be no I/O in flight so it's
874 * ok to free the circular buffer; else just scrub it. And don't
875 * let the push tasklet fire again until we're re-opened.
878 gs_buf_free(&port->port_write_buf);
880 gs_buf_clear(&port->port_write_buf);
882 tty->driver_data = NULL;
883 port->port.tty = NULL;
885 port->openclose = false;
887 pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
888 port->port_num, tty, file);
890 wake_up_interruptible(&port->port.close_wait);
892 spin_unlock_irq(&port->port_lock);
895 static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
897 struct gs_port *port = tty->driver_data;
901 pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
902 port->port_num, tty, count);
904 spin_lock_irqsave(&port->port_lock, flags);
906 count = gs_buf_put(&port->port_write_buf, buf, count);
907 /* treat count == 0 as flush_chars() */
909 status = gs_start_tx(port);
910 spin_unlock_irqrestore(&port->port_lock, flags);
915 static int gs_put_char(struct tty_struct *tty, unsigned char ch)
917 struct gs_port *port = tty->driver_data;
921 pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %pf\n",
922 port->port_num, tty, ch, __builtin_return_address(0));
924 spin_lock_irqsave(&port->port_lock, flags);
925 status = gs_buf_put(&port->port_write_buf, &ch, 1);
926 spin_unlock_irqrestore(&port->port_lock, flags);
931 static void gs_flush_chars(struct tty_struct *tty)
933 struct gs_port *port = tty->driver_data;
936 pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
938 spin_lock_irqsave(&port->port_lock, flags);
941 spin_unlock_irqrestore(&port->port_lock, flags);
944 static int gs_write_room(struct tty_struct *tty)
946 struct gs_port *port = tty->driver_data;
950 spin_lock_irqsave(&port->port_lock, flags);
952 room = gs_buf_space_avail(&port->port_write_buf);
953 spin_unlock_irqrestore(&port->port_lock, flags);
955 pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
956 port->port_num, tty, room);
961 static int gs_chars_in_buffer(struct tty_struct *tty)
963 struct gs_port *port = tty->driver_data;
967 spin_lock_irqsave(&port->port_lock, flags);
968 chars = gs_buf_data_avail(&port->port_write_buf);
969 spin_unlock_irqrestore(&port->port_lock, flags);
971 pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
972 port->port_num, tty, chars);
977 /* undo side effects of setting TTY_THROTTLED */
978 static void gs_unthrottle(struct tty_struct *tty)
980 struct gs_port *port = tty->driver_data;
983 spin_lock_irqsave(&port->port_lock, flags);
984 if (port->port_usb) {
985 /* Kickstart read queue processing. We don't do xon/xoff,
986 * rts/cts, or other handshaking with the host, but if the
987 * read queue backs up enough we'll be NAKing OUT packets.
989 tasklet_schedule(&port->push);
990 pr_vdebug(PREFIX "%d: unthrottle\n", port->port_num);
992 spin_unlock_irqrestore(&port->port_lock, flags);
995 static int gs_break_ctl(struct tty_struct *tty, int duration)
997 struct gs_port *port = tty->driver_data;
999 struct gserial *gser;
1001 pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
1002 port->port_num, duration);
1004 spin_lock_irq(&port->port_lock);
1005 gser = port->port_usb;
1006 if (gser && gser->send_break)
1007 status = gser->send_break(gser, duration);
1008 spin_unlock_irq(&port->port_lock);
1013 static const struct tty_operations gs_tty_ops = {
1017 .put_char = gs_put_char,
1018 .flush_chars = gs_flush_chars,
1019 .write_room = gs_write_room,
1020 .chars_in_buffer = gs_chars_in_buffer,
1021 .unthrottle = gs_unthrottle,
1022 .break_ctl = gs_break_ctl,
1025 /*-------------------------------------------------------------------------*/
1027 static struct tty_driver *gs_tty_driver;
1030 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1032 struct gs_port *port;
1034 port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1038 tty_port_init(&port->port);
1039 spin_lock_init(&port->port_lock);
1040 init_waitqueue_head(&port->drain_wait);
1042 tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
1044 INIT_LIST_HEAD(&port->read_pool);
1045 INIT_LIST_HEAD(&port->read_queue);
1046 INIT_LIST_HEAD(&port->write_pool);
1048 port->port_num = port_num;
1049 port->port_line_coding = *coding;
1051 ports[port_num].port = port;
1057 * gserial_setup - initialize TTY driver for one or more ports
1058 * @g: gadget to associate with these ports
1059 * @count: how many ports to support
1060 * Context: may sleep
1062 * The TTY stack needs to know in advance how many devices it should
1063 * plan to manage. Use this call to set up the ports you will be
1064 * exporting through USB. Later, connect them to functions based
1065 * on what configuration is activated by the USB host; and disconnect
1066 * them as appropriate.
1068 * An example would be a two-configuration device in which both
1069 * configurations expose port 0, but through different functions.
1070 * One configuration could even expose port 1 while the other
1073 * Returns negative errno or zero.
1075 int gserial_setup(struct usb_gadget *g, unsigned count)
1078 struct usb_cdc_line_coding coding;
1081 if (count == 0 || count > N_PORTS)
1084 gs_tty_driver = alloc_tty_driver(count);
1088 gs_tty_driver->driver_name = "g_serial";
1089 gs_tty_driver->name = PREFIX;
1090 /* uses dynamically assigned dev_t values */
1092 gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
1093 gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
1094 gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
1095 gs_tty_driver->init_termios = tty_std_termios;
1097 /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1098 * MS-Windows. Otherwise, most of these flags shouldn't affect
1099 * anything unless we were to actually hook up to a serial line.
1101 gs_tty_driver->init_termios.c_cflag =
1102 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1103 gs_tty_driver->init_termios.c_ispeed = 9600;
1104 gs_tty_driver->init_termios.c_ospeed = 9600;
1106 coding.dwDTERate = cpu_to_le32(9600);
1107 coding.bCharFormat = 8;
1108 coding.bParityType = USB_CDC_NO_PARITY;
1109 coding.bDataBits = USB_CDC_1_STOP_BITS;
1111 tty_set_operations(gs_tty_driver, &gs_tty_ops);
1113 /* make devices be openable */
1114 for (i = 0; i < count; i++) {
1115 mutex_init(&ports[i].lock);
1116 status = gs_port_alloc(i, &coding);
1124 /* export the driver ... */
1125 status = tty_register_driver(gs_tty_driver);
1127 pr_err("%s: cannot register, err %d\n",
1132 /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1133 for (i = 0; i < count; i++) {
1134 struct device *tty_dev;
1136 tty_dev = tty_port_register_device(&ports[i].port->port,
1137 gs_tty_driver, i, &g->dev);
1138 if (IS_ERR(tty_dev))
1139 pr_warning("%s: no classdev for port %d, err %ld\n",
1140 __func__, i, PTR_ERR(tty_dev));
1143 pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1144 count, (count == 1) ? "" : "s");
1149 tty_port_destroy(&ports[count].port->port);
1150 kfree(ports[count].port);
1152 put_tty_driver(gs_tty_driver);
1153 gs_tty_driver = NULL;
1157 static int gs_closed(struct gs_port *port)
1161 spin_lock_irq(&port->port_lock);
1162 cond = (port->port.count == 0) && !port->openclose;
1163 spin_unlock_irq(&port->port_lock);
1168 * gserial_cleanup - remove TTY-over-USB driver and devices
1169 * Context: may sleep
1171 * This is called to free all resources allocated by @gserial_setup().
1172 * Accordingly, it may need to wait until some open /dev/ files have
1175 * The caller must have issued @gserial_disconnect() for any ports
1176 * that had previously been connected, so that there is never any
1177 * I/O pending when it's called.
1179 void gserial_cleanup(void)
1182 struct gs_port *port;
1187 /* start sysfs and /dev/ttyGS* node removal */
1188 for (i = 0; i < n_ports; i++)
1189 tty_unregister_device(gs_tty_driver, i);
1191 for (i = 0; i < n_ports; i++) {
1192 /* prevent new opens */
1193 mutex_lock(&ports[i].lock);
1194 port = ports[i].port;
1195 ports[i].port = NULL;
1196 mutex_unlock(&ports[i].lock);
1198 tasklet_kill(&port->push);
1200 /* wait for old opens to finish */
1201 wait_event(port->port.close_wait, gs_closed(port));
1203 WARN_ON(port->port_usb != NULL);
1205 tty_port_destroy(&port->port);
1210 tty_unregister_driver(gs_tty_driver);
1211 put_tty_driver(gs_tty_driver);
1212 gs_tty_driver = NULL;
1214 pr_debug("%s: cleaned up ttyGS* support\n", __func__);
1218 * gserial_connect - notify TTY I/O glue that USB link is active
1219 * @gser: the function, set up with endpoints and descriptors
1220 * @port_num: which port is active
1221 * Context: any (usually from irq)
1223 * This is called activate endpoints and let the TTY layer know that
1224 * the connection is active ... not unlike "carrier detect". It won't
1225 * necessarily start I/O queues; unless the TTY is held open by any
1226 * task, there would be no point. However, the endpoints will be
1227 * activated so the USB host can perform I/O, subject to basic USB
1228 * hardware flow control.
1230 * Caller needs to have set up the endpoints and USB function in @dev
1231 * before calling this, as well as the appropriate (speed-specific)
1232 * endpoint descriptors, and also have set up the TTY driver by calling
1235 * Returns negative errno or zero.
1236 * On success, ep->driver_data will be overwritten.
1238 int gserial_connect(struct gserial *gser, u8 port_num)
1240 struct gs_port *port;
1241 unsigned long flags;
1244 if (!gs_tty_driver || port_num >= n_ports)
1247 /* we "know" gserial_cleanup() hasn't been called */
1248 port = ports[port_num].port;
1250 /* activate the endpoints */
1251 status = usb_ep_enable(gser->in);
1254 gser->in->driver_data = port;
1256 status = usb_ep_enable(gser->out);
1259 gser->out->driver_data = port;
1261 /* then tell the tty glue that I/O can work */
1262 spin_lock_irqsave(&port->port_lock, flags);
1263 gser->ioport = port;
1264 port->port_usb = gser;
1266 /* REVISIT unclear how best to handle this state...
1267 * we don't really couple it with the Linux TTY.
1269 gser->port_line_coding = port->port_line_coding;
1271 /* REVISIT if waiting on "carrier detect", signal. */
1273 /* if it's already open, start I/O ... and notify the serial
1274 * protocol about open/close status (connect/disconnect).
1276 if (port->port.count) {
1277 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1280 gser->connect(gser);
1282 if (gser->disconnect)
1283 gser->disconnect(gser);
1286 spin_unlock_irqrestore(&port->port_lock, flags);
1291 usb_ep_disable(gser->in);
1292 gser->in->driver_data = NULL;
1297 * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1298 * @gser: the function, on which gserial_connect() was called
1299 * Context: any (usually from irq)
1301 * This is called to deactivate endpoints and let the TTY layer know
1302 * that the connection went inactive ... not unlike "hangup".
1304 * On return, the state is as if gserial_connect() had never been called;
1305 * there is no active USB I/O on these endpoints.
1307 void gserial_disconnect(struct gserial *gser)
1309 struct gs_port *port = gser->ioport;
1310 unsigned long flags;
1315 /* tell the TTY glue not to do I/O here any more */
1316 spin_lock_irqsave(&port->port_lock, flags);
1318 /* REVISIT as above: how best to track this? */
1319 port->port_line_coding = gser->port_line_coding;
1321 port->port_usb = NULL;
1322 gser->ioport = NULL;
1323 if (port->port.count > 0 || port->openclose) {
1324 wake_up_interruptible(&port->drain_wait);
1326 tty_hangup(port->port.tty);
1328 spin_unlock_irqrestore(&port->port_lock, flags);
1330 /* disable endpoints, aborting down any active I/O */
1331 usb_ep_disable(gser->out);
1332 gser->out->driver_data = NULL;
1334 usb_ep_disable(gser->in);
1335 gser->in->driver_data = NULL;
1337 /* finally, free any unused/unusable I/O buffers */
1338 spin_lock_irqsave(&port->port_lock, flags);
1339 if (port->port.count == 0 && !port->openclose)
1340 gs_buf_free(&port->port_write_buf);
1341 gs_free_requests(gser->out, &port->read_pool, NULL);
1342 gs_free_requests(gser->out, &port->read_queue, NULL);
1343 gs_free_requests(gser->in, &port->write_pool, NULL);
1345 port->read_allocated = port->read_started =
1346 port->write_allocated = port->write_started = 0;
1348 spin_unlock_irqrestore(&port->port_lock, flags);