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>
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 this module has been loaded, the individual TTY port can be requested
39 * (gserial_alloc_line()) and it will stay available until they are removed
40 * (gserial_free_line()). Each one may be connected to a USB function
41 * (gserial_connect), or disconnected (with gserial_disconnect) when the USB
42 * host issues a config change event. Data can only flow when the port is
43 * connected to the host.
45 * A given TTY port can be made available in multiple configurations.
46 * For example, each one might expose a ttyGS0 node which provides a
47 * login application. In one case that might use CDC ACM interface 0,
48 * while another configuration might use interface 3 for that. The
49 * work to handle that (including descriptor management) is not part
52 * Configurations may expose more than one TTY port. For example, if
53 * ttyGS0 provides login service, then ttyGS1 might provide dialer access
54 * for a telephone or fax link. And ttyGS2 might be something that just
55 * needs a simple byte stream interface for some messaging protocol that
56 * is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
59 #define PREFIX "ttyGS"
62 * gserial is the lifecycle interface, used by USB functions
63 * gs_port is the I/O nexus, used by the tty driver
64 * tty_struct links to the tty/filesystem framework
66 * gserial <---> gs_port ... links will be null when the USB link is
67 * inactive; managed by gserial_{connect,disconnect}(). each gserial
68 * instance can wrap its own USB control protocol.
69 * gserial->ioport == usb_ep->driver_data ... gs_port
70 * gs_port->port_usb ... gserial
72 * gs_port <---> tty_struct ... links will be null when the TTY file
73 * isn't opened; managed by gs_open()/gs_close()
74 * gserial->port_tty ... tty_struct
75 * tty_struct->driver_data ... gserial
78 /* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
79 * next layer of buffering. For TX that's a circular buffer; for RX
80 * consider it a NOP. A third layer is provided by the TTY code.
83 #define WRITE_BUF_SIZE (2*1024) /* 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 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 */
133 #define pr_vdebug(fmt, arg...) \
135 #endif /* pr_vdebug */
138 #define pr_vdebug(fmt, arg...) \
139 ({ if (0) pr_debug(fmt, ##arg); })
140 #endif /* pr_vdebug */
143 /*-------------------------------------------------------------------------*/
145 /* Circular Buffer */
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)
159 gb->buf_put = gb->buf_buf;
160 gb->buf_get = gb->buf_buf;
168 * Free the buffer and all associated memory.
170 static void gs_buf_free(struct gs_buf *gb)
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 */
190 * Return the number of bytes of data written into the circular
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;
201 * Return the number of bytes of space available in the circular
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;
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.
218 gs_buf_put(struct gs_buf *gb, const char *buf, unsigned count)
222 len = gs_buf_space_avail(gb);
229 len = gb->buf_buf + gb->buf_size - gb->buf_put;
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;
235 memcpy(gb->buf_put, buf, count);
237 gb->buf_put += count;
238 else /* count == len */
239 gb->buf_put = gb->buf_buf;
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.
254 gs_buf_get(struct gs_buf *gb, char *buf, unsigned count)
258 len = gs_buf_data_avail(gb);
265 len = gb->buf_buf + gb->buf_size - gb->buf_get;
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;
271 memcpy(buf, gb->buf_get, count);
273 gb->buf_get += count;
274 else /* count == len */
275 gb->buf_get = gb->buf_buf;
281 /*-------------------------------------------------------------------------*/
283 /* I/O glue between TTY (upper) and USB function (lower) driver layers */
288 * Allocate a usb_request and its buffer. Returns a pointer to the
289 * usb_request or NULL if there is an error.
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);
300 req->buf = kmalloc(len, kmalloc_flags);
301 if (req->buf == NULL) {
302 usb_ep_free_request(ep, req);
309 EXPORT_SYMBOL_GPL(gs_alloc_req);
314 * Free a usb_request and its buffer.
316 void gs_free_req(struct usb_ep *ep, struct usb_request *req)
319 usb_ep_free_request(ep, req);
321 EXPORT_SYMBOL_GPL(gs_free_req);
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.
333 gs_send_packet(struct gs_port *port, char *packet, unsigned size)
337 len = gs_buf_data_avail(&port->port_write_buf);
341 size = gs_buf_get(&port->port_write_buf, packet, size);
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;
365 bool do_tty_wake = false;
367 while (!list_empty(pool)) {
368 struct usb_request *req;
371 if (port->write_started >= QUEUE_SIZE)
374 req = list_entry(pool->next, struct usb_request, list);
375 len = gs_send_packet(port, req->buf, WRITE_BUF_SIZE);
377 wake_up_interruptible(&port->drain_wait);
383 list_del(&req->list);
384 if(len >= in->maxpacket)
385 req->zero = ((len%in->maxpacket) == 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 /* leave data queued if tty was rx throttled */
499 if (tty && test_bit(TTY_THROTTLED, &tty->flags))
502 switch (req->status) {
505 pr_vdebug(PREFIX "%d: shutdown\n", port->port_num);
509 /* presumably a transient fault */
510 pr_warning(PREFIX "%d: unexpected RX status %d\n",
511 port->port_num, req->status);
514 /* normal completion */
518 /* push data to (open) tty */
520 char *packet = req->buf;
521 unsigned size = req->actual;
525 /* we may have pushed part of this packet already... */
532 count = tty_insert_flip_string(&port->port, packet,
537 /* stop pushing; TTY layer can't handle more */
538 port->n_read += count;
539 pr_vdebug(PREFIX "%d: rx block %d/%d\n",
547 list_move(&req->list, &port->read_pool);
548 port->read_started--;
551 /* Push from tty to ldisc; without low_latency set this is handled by
552 * a workqueue, so we won't get callbacks and can hold port_lock
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)) {
569 tasklet_schedule(&port->push);
571 pr_warning(PREFIX "%d: RX not scheduled?\n",
576 /* If we're still connected, refill the USB RX queue. */
577 if (!disconnect && port->port_usb)
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 spin_unlock(&port->port_lock);
591 tasklet_schedule(&port->push);
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) {
604 /* presumably a transient fault */
605 pr_warning("%s: unexpected %s status %d\n",
606 __func__, ep->name, req->status);
609 /* normal completion */
615 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
619 spin_unlock(&port->port_lock);
622 static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
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);
636 static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
637 void (*fn)(struct usb_ep *, struct usb_request *),
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, WRITE_BUF_SIZE, GFP_ATOMIC);
651 return list_empty(head) ? -ENOMEM : 0;
653 list_add_tail(&req->list, head);
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;
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);
687 status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
688 gs_write_complete, &port->write_allocated);
690 gs_free_requests(ep, head, &port->read_allocated);
694 /* queue read requests */
696 started = gs_start_rx(port);
698 /* unblock any pending writes into our circular buffer */
701 tty_wakeup(port->port.tty);
703 gs_free_requests(ep, head, &port->read_allocated);
704 gs_free_requests(port->port_usb->in, &port->write_pool,
705 &port->write_allocated);
712 /*-------------------------------------------------------------------------*/
717 * gs_open sets up the link between a gs_port and its associated TTY.
718 * That link is broken *only* by TTY close(), and all driver methods
721 static int gs_open(struct tty_struct *tty, struct file *file)
723 int port_num = tty->index;
724 struct gs_port *port;
728 mutex_lock(&ports[port_num].lock);
729 port = ports[port_num].port;
733 spin_lock_irq(&port->port_lock);
735 /* already open? Great. */
736 if (port->port.count) {
740 /* currently opening/closing? wait ... */
741 } else if (port->openclose) {
744 /* ... else we do the work */
747 port->openclose = true;
749 spin_unlock_irq(&port->port_lock);
751 mutex_unlock(&ports[port_num].lock);
758 /* must do the work */
761 /* wait for EAGAIN task to finish */
763 /* REVISIT could have a waitchannel here, if
764 * concurrent open performance is important
768 } while (status != -EAGAIN);
770 /* Do the "real open" */
771 spin_lock_irq(&port->port_lock);
773 /* allocate circular buffer on first open */
774 if (port->port_write_buf.buf_buf == NULL) {
776 spin_unlock_irq(&port->port_lock);
777 status = gs_buf_alloc(&port->port_write_buf, WRITE_BUF_SIZE);
778 spin_lock_irq(&port->port_lock);
781 pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
782 port->port_num, tty, file);
783 port->openclose = false;
784 goto exit_unlock_port;
788 /* REVISIT if REMOVED (ports[].port NULL), abort the open
789 * to let rmmod work faster (but this way isn't wrong).
792 /* REVISIT maybe wait for "carrier detect" */
794 tty->driver_data = port;
795 port->port.tty = tty;
797 port->port.count = 1;
798 port->openclose = false;
800 /* if connected, start the I/O stream */
801 if (port->port_usb) {
802 struct gserial *gser = port->port_usb;
804 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
811 pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
816 spin_unlock_irq(&port->port_lock);
820 static int gs_writes_finished(struct gs_port *p)
824 /* return true on disconnect or empty buffer */
825 spin_lock_irq(&p->port_lock);
826 cond = (p->port_usb == NULL) || !gs_buf_data_avail(&p->port_write_buf);
827 spin_unlock_irq(&p->port_lock);
832 static void gs_close(struct tty_struct *tty, struct file *file)
834 struct gs_port *port = tty->driver_data;
835 struct gserial *gser;
837 spin_lock_irq(&port->port_lock);
839 if (port->port.count != 1) {
840 if (port->port.count == 0)
847 pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
849 /* mark port as closing but in use; we can drop port lock
850 * and sleep if necessary
852 port->openclose = true;
853 port->port.count = 0;
855 gser = port->port_usb;
856 if (gser && gser->disconnect)
857 gser->disconnect(gser);
859 /* wait for circular write buffer to drain, disconnect, or at
860 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
862 if (gs_buf_data_avail(&port->port_write_buf) > 0 && gser) {
863 spin_unlock_irq(&port->port_lock);
864 wait_event_interruptible_timeout(port->drain_wait,
865 gs_writes_finished(port),
866 GS_CLOSE_TIMEOUT * HZ);
867 spin_lock_irq(&port->port_lock);
868 gser = port->port_usb;
871 /* Iff we're disconnected, there can be no I/O in flight so it's
872 * ok to free the circular buffer; else just scrub it. And don't
873 * let the push tasklet fire again until we're re-opened.
876 gs_buf_free(&port->port_write_buf);
878 gs_buf_clear(&port->port_write_buf);
880 tty->driver_data = NULL;
881 port->port.tty = NULL;
883 port->openclose = false;
885 pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
886 port->port_num, tty, file);
888 wake_up(&port->port.close_wait);
890 spin_unlock_irq(&port->port_lock);
893 static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
895 struct gs_port *port = tty->driver_data;
900 pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
901 port->port_num, tty, count);
903 spin_lock_irqsave(&port->port_lock, flags);
905 count = gs_buf_put(&port->port_write_buf, buf, count);
906 /* treat count == 0 as flush_chars() */
908 status = gs_start_tx(port);
909 spin_unlock_irqrestore(&port->port_lock, flags);
914 static int gs_put_char(struct tty_struct *tty, unsigned char ch)
916 struct gs_port *port = tty->driver_data;
922 pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %pf\n",
923 port->port_num, tty, ch, __builtin_return_address(0));
925 spin_lock_irqsave(&port->port_lock, flags);
926 status = gs_buf_put(&port->port_write_buf, &ch, 1);
927 spin_unlock_irqrestore(&port->port_lock, flags);
932 static void gs_flush_chars(struct tty_struct *tty)
934 struct gs_port *port = tty->driver_data;
939 pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
941 spin_lock_irqsave(&port->port_lock, flags);
944 spin_unlock_irqrestore(&port->port_lock, flags);
947 static int gs_write_room(struct tty_struct *tty)
949 struct gs_port *port = tty->driver_data;
954 spin_lock_irqsave(&port->port_lock, flags);
956 room = gs_buf_space_avail(&port->port_write_buf);
957 spin_unlock_irqrestore(&port->port_lock, flags);
959 pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
960 port->port_num, tty, room);
965 static int gs_chars_in_buffer(struct tty_struct *tty)
967 struct gs_port *port = tty->driver_data;
973 spin_lock_irqsave(&port->port_lock, flags);
974 chars = gs_buf_data_avail(&port->port_write_buf);
975 spin_unlock_irqrestore(&port->port_lock, flags);
977 pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
978 port->port_num, tty, chars);
983 /* undo side effects of setting TTY_THROTTLED */
984 static void gs_unthrottle(struct tty_struct *tty)
986 struct gs_port *port = tty->driver_data;
991 spin_lock_irqsave(&port->port_lock, flags);
992 if (port->port_usb) {
993 /* Kickstart read queue processing. We don't do xon/xoff,
994 * rts/cts, or other handshaking with the host, but if the
995 * read queue backs up enough we'll be NAKing OUT packets.
997 tasklet_schedule(&port->push);
998 pr_vdebug(PREFIX "%d: unthrottle\n", port->port_num);
1000 spin_unlock_irqrestore(&port->port_lock, flags);
1003 static int gs_break_ctl(struct tty_struct *tty, int duration)
1005 struct gs_port *port = tty->driver_data;
1007 struct gserial *gser;
1011 pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
1012 port->port_num, duration);
1014 spin_lock_irq(&port->port_lock);
1015 gser = port->port_usb;
1016 if (gser && gser->send_break)
1017 status = gser->send_break(gser, duration);
1018 spin_unlock_irq(&port->port_lock);
1023 static const struct tty_operations gs_tty_ops = {
1027 .put_char = gs_put_char,
1028 .flush_chars = gs_flush_chars,
1029 .write_room = gs_write_room,
1030 .chars_in_buffer = gs_chars_in_buffer,
1031 .unthrottle = gs_unthrottle,
1032 .break_ctl = gs_break_ctl,
1035 /*-------------------------------------------------------------------------*/
1037 static struct tty_driver *gs_tty_driver;
1040 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1042 struct gs_port *port;
1045 mutex_lock(&ports[port_num].lock);
1046 if (ports[port_num].port) {
1051 port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1057 tty_port_init(&port->port);
1058 spin_lock_init(&port->port_lock);
1059 init_waitqueue_head(&port->drain_wait);
1061 tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
1063 INIT_LIST_HEAD(&port->read_pool);
1064 INIT_LIST_HEAD(&port->read_queue);
1065 INIT_LIST_HEAD(&port->write_pool);
1067 port->port_num = port_num;
1068 port->port_line_coding = *coding;
1070 ports[port_num].port = port;
1072 mutex_unlock(&ports[port_num].lock);
1076 static int gs_closed(struct gs_port *port)
1080 spin_lock_irq(&port->port_lock);
1081 cond = (port->port.count == 0) && !port->openclose;
1082 spin_unlock_irq(&port->port_lock);
1086 static void gserial_free_port(struct gs_port *port)
1088 tasklet_kill(&port->push);
1089 /* wait for old opens to finish */
1090 wait_event(port->port.close_wait, gs_closed(port));
1091 WARN_ON(port->port_usb != NULL);
1092 tty_port_destroy(&port->port);
1096 void gserial_free_line(unsigned char port_num)
1098 struct gs_port *port;
1100 mutex_lock(&ports[port_num].lock);
1101 if (WARN_ON(!ports[port_num].port)) {
1102 mutex_unlock(&ports[port_num].lock);
1105 port = ports[port_num].port;
1106 ports[port_num].port = NULL;
1107 mutex_unlock(&ports[port_num].lock);
1109 gserial_free_port(port);
1110 tty_unregister_device(gs_tty_driver, port_num);
1112 EXPORT_SYMBOL_GPL(gserial_free_line);
1114 int gserial_alloc_line(unsigned char *line_num)
1116 struct usb_cdc_line_coding coding;
1117 struct device *tty_dev;
1121 coding.dwDTERate = cpu_to_le32(9600);
1122 coding.bCharFormat = 8;
1123 coding.bParityType = USB_CDC_NO_PARITY;
1124 coding.bDataBits = USB_CDC_1_STOP_BITS;
1126 for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1127 ret = gs_port_alloc(port_num, &coding);
1137 /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1139 tty_dev = tty_port_register_device(&ports[port_num].port->port,
1140 gs_tty_driver, port_num, NULL);
1142 if (IS_ERR(tty_dev)) {
1143 struct gs_port *port;
1144 pr_err("%s: failed to register tty for port %d, err %ld\n",
1145 __func__, port_num, PTR_ERR(tty_dev));
1147 ret = PTR_ERR(tty_dev);
1148 port = ports[port_num].port;
1149 ports[port_num].port = NULL;
1150 gserial_free_port(port);
1153 *line_num = port_num;
1157 EXPORT_SYMBOL_GPL(gserial_alloc_line);
1160 * gserial_connect - notify TTY I/O glue that USB link is active
1161 * @gser: the function, set up with endpoints and descriptors
1162 * @port_num: which port is active
1163 * Context: any (usually from irq)
1165 * This is called activate endpoints and let the TTY layer know that
1166 * the connection is active ... not unlike "carrier detect". It won't
1167 * necessarily start I/O queues; unless the TTY is held open by any
1168 * task, there would be no point. However, the endpoints will be
1169 * activated so the USB host can perform I/O, subject to basic USB
1170 * hardware flow control.
1172 * Caller needs to have set up the endpoints and USB function in @dev
1173 * before calling this, as well as the appropriate (speed-specific)
1174 * endpoint descriptors, and also have allocate @port_num by calling
1175 * @gserial_alloc_line().
1177 * Returns negative errno or zero.
1178 * On success, ep->driver_data will be overwritten.
1180 int gserial_connect(struct gserial *gser, u8 port_num)
1182 struct gs_port *port;
1183 unsigned long flags;
1186 if (port_num >= MAX_U_SERIAL_PORTS)
1189 port = ports[port_num].port;
1191 pr_err("serial line %d not allocated.\n", port_num);
1194 if (port->port_usb) {
1195 pr_err("serial line %d is in use.\n", port_num);
1199 /* activate the endpoints */
1200 status = usb_ep_enable(gser->in);
1203 gser->in->driver_data = port;
1205 status = usb_ep_enable(gser->out);
1208 gser->out->driver_data = port;
1210 /* then tell the tty glue that I/O can work */
1211 spin_lock_irqsave(&port->port_lock, flags);
1212 gser->ioport = port;
1213 port->port_usb = gser;
1215 /* REVISIT unclear how best to handle this state...
1216 * we don't really couple it with the Linux TTY.
1218 gser->port_line_coding = port->port_line_coding;
1220 /* REVISIT if waiting on "carrier detect", signal. */
1222 /* if it's already open, start I/O ... and notify the serial
1223 * protocol about open/close status (connect/disconnect).
1225 if (port->port.count) {
1226 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1229 gser->connect(gser);
1231 if (gser->disconnect)
1232 gser->disconnect(gser);
1235 spin_unlock_irqrestore(&port->port_lock, flags);
1240 usb_ep_disable(gser->in);
1241 gser->in->driver_data = NULL;
1244 EXPORT_SYMBOL_GPL(gserial_connect);
1246 * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1247 * @gser: the function, on which gserial_connect() was called
1248 * Context: any (usually from irq)
1250 * This is called to deactivate endpoints and let the TTY layer know
1251 * that the connection went inactive ... not unlike "hangup".
1253 * On return, the state is as if gserial_connect() had never been called;
1254 * there is no active USB I/O on these endpoints.
1256 void gserial_disconnect(struct gserial *gser)
1258 struct gs_port *port = gser->ioport;
1259 unsigned long flags;
1264 /* tell the TTY glue not to do I/O here any more */
1265 spin_lock_irqsave(&port->port_lock, flags);
1267 /* REVISIT as above: how best to track this? */
1268 port->port_line_coding = gser->port_line_coding;
1270 port->port_usb = NULL;
1271 gser->ioport = NULL;
1272 if (port->port.count > 0 || port->openclose) {
1273 wake_up_interruptible(&port->drain_wait);
1275 tty_hangup(port->port.tty);
1277 spin_unlock_irqrestore(&port->port_lock, flags);
1279 /* disable endpoints, aborting down any active I/O */
1280 usb_ep_disable(gser->out);
1281 gser->out->driver_data = NULL;
1283 usb_ep_disable(gser->in);
1284 gser->in->driver_data = NULL;
1286 /* finally, free any unused/unusable I/O buffers */
1287 spin_lock_irqsave(&port->port_lock, flags);
1288 if (port->port.count == 0 && !port->openclose)
1289 gs_buf_free(&port->port_write_buf);
1290 gs_free_requests(gser->out, &port->read_pool, NULL);
1291 gs_free_requests(gser->out, &port->read_queue, NULL);
1292 gs_free_requests(gser->in, &port->write_pool, NULL);
1294 port->read_allocated = port->read_started =
1295 port->write_allocated = port->write_started = 0;
1297 spin_unlock_irqrestore(&port->port_lock, flags);
1299 EXPORT_SYMBOL_GPL(gserial_disconnect);
1301 static int userial_init(void)
1306 gs_tty_driver = alloc_tty_driver(MAX_U_SERIAL_PORTS);
1310 gs_tty_driver->driver_name = "g_serial";
1311 gs_tty_driver->name = PREFIX;
1312 /* uses dynamically assigned dev_t values */
1314 gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
1315 gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
1316 gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
1317 gs_tty_driver->init_termios = tty_std_termios;
1319 /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1320 * MS-Windows. Otherwise, most of these flags shouldn't affect
1321 * anything unless we were to actually hook up to a serial line.
1323 gs_tty_driver->init_termios.c_cflag =
1324 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1325 gs_tty_driver->init_termios.c_ispeed = 9600;
1326 gs_tty_driver->init_termios.c_ospeed = 9600;
1328 tty_set_operations(gs_tty_driver, &gs_tty_ops);
1329 for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1330 mutex_init(&ports[i].lock);
1332 /* export the driver ... */
1333 status = tty_register_driver(gs_tty_driver);
1335 pr_err("%s: cannot register, err %d\n",
1340 pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1342 (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1346 put_tty_driver(gs_tty_driver);
1347 gs_tty_driver = NULL;
1350 module_init(userial_init);
1352 static void userial_cleanup(void)
1354 tty_unregister_driver(gs_tty_driver);
1355 put_tty_driver(gs_tty_driver);
1356 gs_tty_driver = NULL;
1358 module_exit(userial_cleanup);
1360 MODULE_LICENSE("GPL");