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>
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
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.
81 #define WRITE_BUF_SIZE 8192 /* TX only */
92 * The port structure holds info for each port, one for each minor number
93 * (and thus for each /dev/ node).
97 spinlock_t port_lock; /* guard port_* access */
99 struct gserial *port_usb;
101 bool openclose; /* open/close in progress */
104 struct list_head read_pool;
107 struct list_head read_queue;
109 struct tasklet_struct push;
111 struct list_head write_pool;
114 struct gs_buf port_write_buf;
115 wait_queue_head_t drain_wait; /* wait while writes drain */
117 /* REVISIT this state ... */
118 struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
121 static struct portmaster {
122 struct mutex lock; /* protect open/close */
123 struct gs_port *port;
124 } ports[MAX_U_SERIAL_PORTS];
126 #define GS_CLOSE_TIMEOUT 15 /* seconds */
132 #define pr_vdebug(fmt, arg...) \
134 #endif /* pr_vdebug */
137 #define pr_vdebug(fmt, arg...) \
138 ({ if (0) pr_debug(fmt, ##arg); })
139 #endif /* pr_vdebug */
142 /*-------------------------------------------------------------------------*/
144 /* Circular Buffer */
149 * Allocate a circular buffer and all associated memory.
151 static int gs_buf_alloc(struct gs_buf *gb, unsigned size)
153 gb->buf_buf = kmalloc(size, GFP_KERNEL);
154 if (gb->buf_buf == NULL)
158 gb->buf_put = gb->buf_buf;
159 gb->buf_get = gb->buf_buf;
167 * Free the buffer and all associated memory.
169 static void gs_buf_free(struct gs_buf *gb)
178 * Clear out all data in the circular buffer.
180 static void gs_buf_clear(struct gs_buf *gb)
182 gb->buf_get = gb->buf_put;
183 /* equivalent to a get of all data available */
189 * Return the number of bytes of data written into the circular
192 static unsigned gs_buf_data_avail(struct gs_buf *gb)
194 return (gb->buf_size + gb->buf_put - gb->buf_get) % gb->buf_size;
200 * Return the number of bytes of space available in the circular
203 static unsigned gs_buf_space_avail(struct gs_buf *gb)
205 return (gb->buf_size + gb->buf_get - gb->buf_put - 1) % gb->buf_size;
211 * Copy data data from a user buffer and put it into the circular buffer.
212 * Restrict to the amount of space available.
214 * Return the number of bytes copied.
217 gs_buf_put(struct gs_buf *gb, const char *buf, unsigned count)
221 len = gs_buf_space_avail(gb);
228 len = gb->buf_buf + gb->buf_size - gb->buf_put;
230 memcpy(gb->buf_put, buf, len);
231 memcpy(gb->buf_buf, buf+len, count - len);
232 gb->buf_put = gb->buf_buf + count - len;
234 memcpy(gb->buf_put, buf, count);
236 gb->buf_put += count;
237 else /* count == len */
238 gb->buf_put = gb->buf_buf;
247 * Get data from the circular buffer and copy to the given buffer.
248 * Restrict to the amount of data available.
250 * Return the number of bytes copied.
253 gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
257 len = gs_buf_data_avail(gb);
264 len = gb->buf_buf + gb->buf_size - gb->buf_get;
266 memcpy(buf, gb->buf_get, len);
267 memcpy(buf+len, gb->buf_buf, count - len);
268 gb->buf_get = gb->buf_buf + count - len;
270 memcpy(buf, gb->buf_get, count);
272 gb->buf_get += count;
273 else /* count == len */
274 gb->buf_get = gb->buf_buf;
280 /*-------------------------------------------------------------------------*/
282 /* I/O glue between TTY (upper) and USB function (lower) driver layers */
287 * Allocate a usb_request and its buffer. Returns a pointer to the
288 * usb_request or NULL if there is an error.
291 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
293 struct usb_request *req;
295 req = usb_ep_alloc_request(ep, kmalloc_flags);
299 req->buf = kmalloc(len, kmalloc_flags);
300 if (req->buf == NULL) {
301 usb_ep_free_request(ep, req);
308 EXPORT_SYMBOL_GPL(gs_alloc_req);
313 * Free a usb_request and its buffer.
315 void gs_free_req(struct usb_ep *ep, struct usb_request *req)
318 usb_ep_free_request(ep, req);
320 EXPORT_SYMBOL_GPL(gs_free_req);
325 * If there is data to send, a packet is built in the given
326 * buffer and the size is returned. If there is no data to
327 * send, 0 is returned.
329 * Called with port_lock held.
332 gs_send_packet(struct gs_port *port, char *packet, unsigned size)
336 len = gs_buf_data_avail(&port->port_write_buf);
340 size = gs_buf_get(&port->port_write_buf, packet, size);
347 * This function finds available write requests, calls
348 * gs_send_packet to fill these packets with data, and
349 * continues until either there are no more write requests
350 * available or no more data to send. This function is
351 * run whenever data arrives or write requests are available.
353 * Context: caller owns port_lock; port_usb is non-null.
355 static int gs_start_tx(struct gs_port *port)
357 __releases(&port->port_lock)
358 __acquires(&port->port_lock)
361 struct list_head *pool = &port->write_pool;
362 struct usb_ep *in = port->port_usb->in;
364 bool do_tty_wake = false;
366 while (!list_empty(pool)) {
367 struct usb_request *req;
370 if (port->write_started >= QUEUE_SIZE)
373 req = list_entry(pool->next, struct usb_request, list);
374 len = gs_send_packet(port, req->buf, in->maxpacket);
376 wake_up_interruptible(&port->drain_wait);
382 list_del(&req->list);
383 req->zero = (gs_buf_data_avail(&port->port_write_buf) == 0);
385 pr_vdebug("ttyGS%d: tx len=%d, 0x%02x 0x%02x 0x%02x ...\n",
386 port->port_num, len, *((u8 *)req->buf),
387 *((u8 *)req->buf+1), *((u8 *)req->buf+2));
389 /* Drop lock while we call out of driver; completions
390 * could be issued while we do so. Disconnection may
391 * happen too; maybe immediately before we queue this!
393 * NOTE that we may keep sending data for a while after
394 * the TTY closed (dev->ioport->port_tty is NULL).
396 spin_unlock(&port->port_lock);
397 status = usb_ep_queue(in, req, GFP_ATOMIC);
398 spin_lock(&port->port_lock);
401 pr_debug("%s: %s %s err %d\n",
402 __func__, "queue", in->name, status);
403 list_add(&req->list, pool);
407 port->write_started++;
409 /* abort immediately after disconnect */
414 if (do_tty_wake && port->port.tty)
415 tty_wakeup(port->port.tty);
420 * Context: caller owns port_lock, and port_usb is set
422 static unsigned gs_start_rx(struct gs_port *port)
424 __releases(&port->port_lock)
425 __acquires(&port->port_lock)
428 struct list_head *pool = &port->read_pool;
429 struct usb_ep *out = port->port_usb->out;
431 while (!list_empty(pool)) {
432 struct usb_request *req;
434 struct tty_struct *tty;
436 /* no more rx if closed */
437 tty = port->port.tty;
441 if (port->read_started >= QUEUE_SIZE)
444 req = list_entry(pool->next, struct usb_request, list);
445 list_del(&req->list);
446 req->length = out->maxpacket;
448 /* drop lock while we call out; the controller driver
449 * may need to call us back (e.g. for disconnect)
451 spin_unlock(&port->port_lock);
452 status = usb_ep_queue(out, req, GFP_ATOMIC);
453 spin_lock(&port->port_lock);
456 pr_debug("%s: %s %s err %d\n",
457 __func__, "queue", out->name, status);
458 list_add(&req->list, pool);
461 port->read_started++;
463 /* abort immediately after disconnect */
467 return port->read_started;
471 * RX tasklet takes data out of the RX queue and hands it up to the TTY
472 * layer until it refuses to take any more data (or is throttled back).
473 * Then it issues reads for any further data.
475 * If the RX queue becomes full enough that no usb_request is queued,
476 * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
477 * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
478 * can be buffered before the TTY layer's buffers (currently 64 KB).
480 static void gs_rx_push(unsigned long _port)
482 struct gs_port *port = (void *)_port;
483 struct tty_struct *tty;
484 struct list_head *queue = &port->read_queue;
485 bool disconnect = false;
486 bool do_push = false;
488 /* hand any queued data to the tty */
489 spin_lock_irq(&port->port_lock);
490 tty = port->port.tty;
491 while (!list_empty(queue)) {
492 struct usb_request *req;
494 req = list_first_entry(queue, struct usb_request, list);
496 /* leave data queued if tty was rx throttled */
497 if (tty && test_bit(TTY_THROTTLED, &tty->flags))
500 switch (req->status) {
503 pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
507 /* presumably a transient fault */
508 pr_warn("ttyGS%d: unexpected RX status %d\n",
509 port->port_num, req->status);
512 /* normal completion */
516 /* push data to (open) tty */
518 char *packet = req->buf;
519 unsigned size = req->actual;
523 /* we may have pushed part of this packet already... */
530 count = tty_insert_flip_string(&port->port, packet,
535 /* stop pushing; TTY layer can't handle more */
536 port->n_read += count;
537 pr_vdebug("ttyGS%d: rx block %d/%d\n",
538 port->port_num, count, req->actual);
544 list_move(&req->list, &port->read_pool);
545 port->read_started--;
548 /* Push from tty to ldisc; this is handled by a workqueue,
549 * so we won't get callbacks and can hold port_lock
552 tty_flip_buffer_push(&port->port);
555 /* We want our data queue to become empty ASAP, keeping data
556 * in the tty and ldisc (not here). If we couldn't push any
557 * this time around, there may be trouble unless there's an
558 * implicit tty_unthrottle() call on its way...
560 * REVISIT we should probably add a timer to keep the tasklet
561 * from starving ... but it's not clear that case ever happens.
563 if (!list_empty(queue) && tty) {
564 if (!test_bit(TTY_THROTTLED, &tty->flags)) {
566 tasklet_schedule(&port->push);
568 pr_warn("ttyGS%d: RX not scheduled?\n",
573 /* If we're still connected, refill the USB RX queue. */
574 if (!disconnect && port->port_usb)
577 spin_unlock_irq(&port->port_lock);
580 static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
582 struct gs_port *port = ep->driver_data;
584 /* Queue all received data until the tty layer is ready for it. */
585 spin_lock(&port->port_lock);
586 list_add_tail(&req->list, &port->read_queue);
587 tasklet_schedule(&port->push);
588 spin_unlock(&port->port_lock);
591 static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
593 struct gs_port *port = ep->driver_data;
595 spin_lock(&port->port_lock);
596 list_add(&req->list, &port->write_pool);
597 port->write_started--;
599 switch (req->status) {
601 /* presumably a transient fault */
602 pr_warning("%s: unexpected %s status %d\n",
603 __func__, ep->name, req->status);
606 /* normal completion */
612 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
616 spin_unlock(&port->port_lock);
619 static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
622 struct usb_request *req;
624 while (!list_empty(head)) {
625 req = list_entry(head->next, struct usb_request, list);
626 list_del(&req->list);
627 gs_free_req(ep, req);
633 static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
634 void (*fn)(struct usb_ep *, struct usb_request *),
638 struct usb_request *req;
639 int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
641 /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
642 * do quite that many this time, don't fail ... we just won't
643 * be as speedy as we might otherwise be.
645 for (i = 0; i < n; i++) {
646 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
648 return list_empty(head) ? -ENOMEM : 0;
650 list_add_tail(&req->list, head);
658 * gs_start_io - start USB I/O streams
659 * @dev: encapsulates endpoints to use
660 * Context: holding port_lock; port_tty and port_usb are non-null
662 * We only start I/O when something is connected to both sides of
663 * this port. If nothing is listening on the host side, we may
664 * be pointlessly filling up our TX buffers and FIFO.
666 static int gs_start_io(struct gs_port *port)
668 struct list_head *head = &port->read_pool;
669 struct usb_ep *ep = port->port_usb->out;
673 /* Allocate RX and TX I/O buffers. We can't easily do this much
674 * earlier (with GFP_KERNEL) because the requests are coupled to
675 * endpoints, as are the packet sizes we'll be using. Different
676 * configurations may use different endpoints with a given port;
677 * and high speed vs full speed changes packet sizes too.
679 status = gs_alloc_requests(ep, head, gs_read_complete,
680 &port->read_allocated);
684 status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
685 gs_write_complete, &port->write_allocated);
687 gs_free_requests(ep, head, &port->read_allocated);
691 /* queue read requests */
693 started = gs_start_rx(port);
695 /* unblock any pending writes into our circular buffer */
697 tty_wakeup(port->port.tty);
699 gs_free_requests(ep, head, &port->read_allocated);
700 gs_free_requests(port->port_usb->in, &port->write_pool,
701 &port->write_allocated);
708 /*-------------------------------------------------------------------------*/
713 * gs_open sets up the link between a gs_port and its associated TTY.
714 * That link is broken *only* by TTY close(), and all driver methods
717 static int gs_open(struct tty_struct *tty, struct file *file)
719 int port_num = tty->index;
720 struct gs_port *port;
724 mutex_lock(&ports[port_num].lock);
725 port = ports[port_num].port;
729 spin_lock_irq(&port->port_lock);
731 /* already open? Great. */
732 if (port->port.count) {
736 /* currently opening/closing? wait ... */
737 } else if (port->openclose) {
740 /* ... else we do the work */
743 port->openclose = true;
745 spin_unlock_irq(&port->port_lock);
747 mutex_unlock(&ports[port_num].lock);
754 /* must do the work */
757 /* wait for EAGAIN task to finish */
759 /* REVISIT could have a waitchannel here, if
760 * concurrent open performance is important
764 } while (status != -EAGAIN);
766 /* Do the "real open" */
767 spin_lock_irq(&port->port_lock);
769 /* allocate circular buffer on first open */
770 if (port->port_write_buf.buf_buf == NULL) {
772 spin_unlock_irq(&port->port_lock);
773 status = gs_buf_alloc(&port->port_write_buf, WRITE_BUF_SIZE);
774 spin_lock_irq(&port->port_lock);
777 pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
778 port->port_num, tty, file);
779 port->openclose = false;
780 goto exit_unlock_port;
784 /* REVISIT if REMOVED (ports[].port NULL), abort the open
785 * to let rmmod work faster (but this way isn't wrong).
788 /* REVISIT maybe wait for "carrier detect" */
790 tty->driver_data = port;
791 port->port.tty = tty;
793 port->port.count = 1;
794 port->openclose = false;
796 /* if connected, start the I/O stream */
797 if (port->port_usb) {
798 struct gserial *gser = port->port_usb;
800 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
807 pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
812 spin_unlock_irq(&port->port_lock);
816 static int gs_writes_finished(struct gs_port *p)
820 /* return true on disconnect or empty buffer */
821 spin_lock_irq(&p->port_lock);
822 cond = (p->port_usb == NULL) || !gs_buf_data_avail(&p->port_write_buf);
823 spin_unlock_irq(&p->port_lock);
828 static void gs_close(struct tty_struct *tty, struct file *file)
830 struct gs_port *port = tty->driver_data;
831 struct gserial *gser;
833 spin_lock_irq(&port->port_lock);
835 if (port->port.count != 1) {
836 if (port->port.count == 0)
843 pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
845 /* mark port as closing but in use; we can drop port lock
846 * and sleep if necessary
848 port->openclose = true;
849 port->port.count = 0;
851 gser = port->port_usb;
852 if (gser && gser->disconnect)
853 gser->disconnect(gser);
855 /* wait for circular write buffer to drain, disconnect, or at
856 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
858 if (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) {
859 spin_unlock_irq(&port->port_lock);
860 wait_event_interruptible_timeout(port->drain_wait,
861 gs_writes_finished(port),
862 GS_CLOSE_TIMEOUT * HZ);
863 spin_lock_irq(&port->port_lock);
864 gser = port->port_usb;
867 /* Iff we're disconnected, there can be no I/O in flight so it's
868 * ok to free the circular buffer; else just scrub it. And don't
869 * let the push tasklet fire again until we're re-opened.
872 gs_buf_free(&port->port_write_buf);
874 gs_buf_clear(&port->port_write_buf);
876 tty->driver_data = NULL;
877 port->port.tty = NULL;
879 port->openclose = false;
881 pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
882 port->port_num, tty, file);
884 wake_up(&port->port.close_wait);
886 spin_unlock_irq(&port->port_lock);
889 static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
891 struct gs_port *port = tty->driver_data;
895 pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
896 port->port_num, tty, count);
898 spin_lock_irqsave(&port->port_lock, flags);
900 count = gs_buf_put(&port->port_write_buf, buf, count);
901 /* treat count == 0 as flush_chars() */
903 status = gs_start_tx(port);
904 spin_unlock_irqrestore(&port->port_lock, flags);
909 static int gs_put_char(struct tty_struct *tty, unsigned char ch)
911 struct gs_port *port = tty->driver_data;
915 pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
916 port->port_num, tty, ch, __builtin_return_address(0));
918 spin_lock_irqsave(&port->port_lock, flags);
919 status = gs_buf_put(&port->port_write_buf, &ch, 1);
920 spin_unlock_irqrestore(&port->port_lock, flags);
925 static void gs_flush_chars(struct tty_struct *tty)
927 struct gs_port *port = tty->driver_data;
930 pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
932 spin_lock_irqsave(&port->port_lock, flags);
935 spin_unlock_irqrestore(&port->port_lock, flags);
938 static int gs_write_room(struct tty_struct *tty)
940 struct gs_port *port = tty->driver_data;
944 spin_lock_irqsave(&port->port_lock, flags);
946 room = gs_buf_space_avail(&port->port_write_buf);
947 spin_unlock_irqrestore(&port->port_lock, flags);
949 pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
950 port->port_num, tty, room);
955 static int gs_chars_in_buffer(struct tty_struct *tty)
957 struct gs_port *port = tty->driver_data;
961 spin_lock_irqsave(&port->port_lock, flags);
962 chars = gs_buf_data_avail(&port->port_write_buf);
963 spin_unlock_irqrestore(&port->port_lock, flags);
965 pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
966 port->port_num, tty, chars);
971 /* undo side effects of setting TTY_THROTTLED */
972 static void gs_unthrottle(struct tty_struct *tty)
974 struct gs_port *port = tty->driver_data;
977 spin_lock_irqsave(&port->port_lock, flags);
978 if (port->port_usb) {
979 /* Kickstart read queue processing. We don't do xon/xoff,
980 * rts/cts, or other handshaking with the host, but if the
981 * read queue backs up enough we'll be NAKing OUT packets.
983 tasklet_schedule(&port->push);
984 pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
986 spin_unlock_irqrestore(&port->port_lock, flags);
989 static int gs_break_ctl(struct tty_struct *tty, int duration)
991 struct gs_port *port = tty->driver_data;
993 struct gserial *gser;
995 pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
996 port->port_num, duration);
998 spin_lock_irq(&port->port_lock);
999 gser = port->port_usb;
1000 if (gser && gser->send_break)
1001 status = gser->send_break(gser, duration);
1002 spin_unlock_irq(&port->port_lock);
1007 static const struct tty_operations gs_tty_ops = {
1011 .put_char = gs_put_char,
1012 .flush_chars = gs_flush_chars,
1013 .write_room = gs_write_room,
1014 .chars_in_buffer = gs_chars_in_buffer,
1015 .unthrottle = gs_unthrottle,
1016 .break_ctl = gs_break_ctl,
1019 /*-------------------------------------------------------------------------*/
1021 static struct tty_driver *gs_tty_driver;
1024 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1026 struct gs_port *port;
1029 mutex_lock(&ports[port_num].lock);
1030 if (ports[port_num].port) {
1035 port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1041 tty_port_init(&port->port);
1042 spin_lock_init(&port->port_lock);
1043 init_waitqueue_head(&port->drain_wait);
1045 tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
1047 INIT_LIST_HEAD(&port->read_pool);
1048 INIT_LIST_HEAD(&port->read_queue);
1049 INIT_LIST_HEAD(&port->write_pool);
1051 port->port_num = port_num;
1052 port->port_line_coding = *coding;
1054 ports[port_num].port = port;
1056 mutex_unlock(&ports[port_num].lock);
1060 static int gs_closed(struct gs_port *port)
1064 spin_lock_irq(&port->port_lock);
1065 cond = (port->port.count == 0) && !port->openclose;
1066 spin_unlock_irq(&port->port_lock);
1070 static void gserial_free_port(struct gs_port *port)
1072 tasklet_kill(&port->push);
1073 /* wait for old opens to finish */
1074 wait_event(port->port.close_wait, gs_closed(port));
1075 WARN_ON(port->port_usb != NULL);
1076 tty_port_destroy(&port->port);
1080 void gserial_free_line(unsigned char port_num)
1082 struct gs_port *port;
1084 mutex_lock(&ports[port_num].lock);
1085 if (WARN_ON(!ports[port_num].port)) {
1086 mutex_unlock(&ports[port_num].lock);
1089 port = ports[port_num].port;
1090 ports[port_num].port = NULL;
1091 mutex_unlock(&ports[port_num].lock);
1093 gserial_free_port(port);
1094 tty_unregister_device(gs_tty_driver, port_num);
1096 EXPORT_SYMBOL_GPL(gserial_free_line);
1098 int gserial_alloc_line(unsigned char *line_num)
1100 struct usb_cdc_line_coding coding;
1101 struct device *tty_dev;
1105 coding.dwDTERate = cpu_to_le32(9600);
1106 coding.bCharFormat = 8;
1107 coding.bParityType = USB_CDC_NO_PARITY;
1108 coding.bDataBits = USB_CDC_1_STOP_BITS;
1110 for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1111 ret = gs_port_alloc(port_num, &coding);
1121 /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1123 tty_dev = tty_port_register_device(&ports[port_num].port->port,
1124 gs_tty_driver, port_num, NULL);
1125 if (IS_ERR(tty_dev)) {
1126 struct gs_port *port;
1127 pr_err("%s: failed to register tty for port %d, err %ld\n",
1128 __func__, port_num, PTR_ERR(tty_dev));
1130 ret = PTR_ERR(tty_dev);
1131 port = ports[port_num].port;
1132 ports[port_num].port = NULL;
1133 gserial_free_port(port);
1136 *line_num = port_num;
1140 EXPORT_SYMBOL_GPL(gserial_alloc_line);
1143 * gserial_connect - notify TTY I/O glue that USB link is active
1144 * @gser: the function, set up with endpoints and descriptors
1145 * @port_num: which port is active
1146 * Context: any (usually from irq)
1148 * This is called activate endpoints and let the TTY layer know that
1149 * the connection is active ... not unlike "carrier detect". It won't
1150 * necessarily start I/O queues; unless the TTY is held open by any
1151 * task, there would be no point. However, the endpoints will be
1152 * activated so the USB host can perform I/O, subject to basic USB
1153 * hardware flow control.
1155 * Caller needs to have set up the endpoints and USB function in @dev
1156 * before calling this, as well as the appropriate (speed-specific)
1157 * endpoint descriptors, and also have allocate @port_num by calling
1158 * @gserial_alloc_line().
1160 * Returns negative errno or zero.
1161 * On success, ep->driver_data will be overwritten.
1163 int gserial_connect(struct gserial *gser, u8 port_num)
1165 struct gs_port *port;
1166 unsigned long flags;
1169 if (port_num >= MAX_U_SERIAL_PORTS)
1172 port = ports[port_num].port;
1174 pr_err("serial line %d not allocated.\n", port_num);
1177 if (port->port_usb) {
1178 pr_err("serial line %d is in use.\n", port_num);
1182 /* activate the endpoints */
1183 status = usb_ep_enable(gser->in);
1186 gser->in->driver_data = port;
1188 status = usb_ep_enable(gser->out);
1191 gser->out->driver_data = port;
1193 /* then tell the tty glue that I/O can work */
1194 spin_lock_irqsave(&port->port_lock, flags);
1195 gser->ioport = port;
1196 port->port_usb = gser;
1198 /* REVISIT unclear how best to handle this state...
1199 * we don't really couple it with the Linux TTY.
1201 gser->port_line_coding = port->port_line_coding;
1203 /* REVISIT if waiting on "carrier detect", signal. */
1205 /* if it's already open, start I/O ... and notify the serial
1206 * protocol about open/close status (connect/disconnect).
1208 if (port->port.count) {
1209 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1212 gser->connect(gser);
1214 if (gser->disconnect)
1215 gser->disconnect(gser);
1218 spin_unlock_irqrestore(&port->port_lock, flags);
1223 usb_ep_disable(gser->in);
1224 gser->in->driver_data = NULL;
1227 EXPORT_SYMBOL_GPL(gserial_connect);
1229 * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1230 * @gser: the function, on which gserial_connect() was called
1231 * Context: any (usually from irq)
1233 * This is called to deactivate endpoints and let the TTY layer know
1234 * that the connection went inactive ... not unlike "hangup".
1236 * On return, the state is as if gserial_connect() had never been called;
1237 * there is no active USB I/O on these endpoints.
1239 void gserial_disconnect(struct gserial *gser)
1241 struct gs_port *port = gser->ioport;
1242 unsigned long flags;
1247 /* tell the TTY glue not to do I/O here any more */
1248 spin_lock_irqsave(&port->port_lock, flags);
1250 /* REVISIT as above: how best to track this? */
1251 port->port_line_coding = gser->port_line_coding;
1253 port->port_usb = NULL;
1254 gser->ioport = NULL;
1255 if (port->port.count > 0 || port->openclose) {
1256 wake_up_interruptible(&port->drain_wait);
1258 tty_hangup(port->port.tty);
1260 spin_unlock_irqrestore(&port->port_lock, flags);
1262 /* disable endpoints, aborting down any active I/O */
1263 usb_ep_disable(gser->out);
1264 gser->out->driver_data = NULL;
1266 usb_ep_disable(gser->in);
1267 gser->in->driver_data = NULL;
1269 /* finally, free any unused/unusable I/O buffers */
1270 spin_lock_irqsave(&port->port_lock, flags);
1271 if (port->port.count == 0 && !port->openclose)
1272 gs_buf_free(&port->port_write_buf);
1273 gs_free_requests(gser->out, &port->read_pool, NULL);
1274 gs_free_requests(gser->out, &port->read_queue, NULL);
1275 gs_free_requests(gser->in, &port->write_pool, NULL);
1277 port->read_allocated = port->read_started =
1278 port->write_allocated = port->write_started = 0;
1280 spin_unlock_irqrestore(&port->port_lock, flags);
1282 EXPORT_SYMBOL_GPL(gserial_disconnect);
1284 static int userial_init(void)
1289 gs_tty_driver = alloc_tty_driver(MAX_U_SERIAL_PORTS);
1293 gs_tty_driver->driver_name = "g_serial";
1294 gs_tty_driver->name = "ttyGS";
1295 /* uses dynamically assigned dev_t values */
1297 gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
1298 gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
1299 gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
1300 gs_tty_driver->init_termios = tty_std_termios;
1302 /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1303 * MS-Windows. Otherwise, most of these flags shouldn't affect
1304 * anything unless we were to actually hook up to a serial line.
1306 gs_tty_driver->init_termios.c_cflag =
1307 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1308 gs_tty_driver->init_termios.c_ispeed = 9600;
1309 gs_tty_driver->init_termios.c_ospeed = 9600;
1311 tty_set_operations(gs_tty_driver, &gs_tty_ops);
1312 for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1313 mutex_init(&ports[i].lock);
1315 /* export the driver ... */
1316 status = tty_register_driver(gs_tty_driver);
1318 pr_err("%s: cannot register, err %d\n",
1323 pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1325 (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1329 put_tty_driver(gs_tty_driver);
1330 gs_tty_driver = NULL;
1333 module_init(userial_init);
1335 static void userial_cleanup(void)
1337 tty_unregister_driver(gs_tty_driver);
1338 put_tty_driver(gs_tty_driver);
1339 gs_tty_driver = NULL;
1341 module_exit(userial_cleanup);
1343 MODULE_LICENSE("GPL");