1 // SPDX-License-Identifier: GPL-2.0+
3 * u_serial.c - utilities for USB gadget "serial port"/TTY support
5 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
6 * Copyright (C) 2008 David Brownell
7 * Copyright (C) 2008 by Nokia Corporation
9 * This code also borrows from usbserial.c, which is
10 * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
11 * Copyright (C) 2000 Peter Berger (pberger@brimson.com)
12 * Copyright (C) 2000 Al Borchers (alborchers@steinerpoint.com)
15 /* #define VERBOSE_DEBUG */
17 #include <linux/kernel.h>
18 #include <linux/sched.h>
19 #include <linux/device.h>
20 #include <linux/delay.h>
21 #include <linux/tty.h>
22 #include <linux/tty_flip.h>
23 #include <linux/slab.h>
24 #include <linux/export.h>
25 #include <linux/module.h>
26 #include <linux/console.h>
27 #include <linux/kthread.h>
28 #include <linux/workqueue.h>
29 #include <linux/kfifo.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 */
82 #define GS_CONSOLE_BUF_SIZE 8192
86 struct console console;
87 struct work_struct work;
89 struct usb_request *req;
95 * The port structure holds info for each port, one for each minor number
96 * (and thus for each /dev/ node).
100 spinlock_t port_lock; /* guard port_* access */
102 struct gserial *port_usb;
103 #ifdef CONFIG_U_SERIAL_CONSOLE
104 struct gs_console *console;
109 struct list_head read_pool;
112 struct list_head read_queue;
114 struct delayed_work push;
116 struct list_head write_pool;
119 struct kfifo port_write_buf;
120 wait_queue_head_t drain_wait; /* wait while writes drain */
122 wait_queue_head_t close_wait;
123 bool suspended; /* port suspended */
124 bool start_delayed; /* delay start when suspended */
126 /* REVISIT this state ... */
127 struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
130 static struct portmaster {
131 struct mutex lock; /* protect open/close */
132 struct gs_port *port;
133 } ports[MAX_U_SERIAL_PORTS];
135 #define GS_CLOSE_TIMEOUT 15 /* seconds */
141 #define pr_vdebug(fmt, arg...) \
143 #endif /* pr_vdebug */
146 #define pr_vdebug(fmt, arg...) \
147 ({ if (0) pr_debug(fmt, ##arg); })
148 #endif /* pr_vdebug */
151 /*-------------------------------------------------------------------------*/
153 /* I/O glue between TTY (upper) and USB function (lower) driver layers */
158 * Allocate a usb_request and its buffer. Returns a pointer to the
159 * usb_request or NULL if there is an error.
162 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
164 struct usb_request *req;
166 req = usb_ep_alloc_request(ep, kmalloc_flags);
170 req->buf = kmalloc(len, kmalloc_flags);
171 if (req->buf == NULL) {
172 usb_ep_free_request(ep, req);
179 EXPORT_SYMBOL_GPL(gs_alloc_req);
184 * Free a usb_request and its buffer.
186 void gs_free_req(struct usb_ep *ep, struct usb_request *req)
189 usb_ep_free_request(ep, req);
191 EXPORT_SYMBOL_GPL(gs_free_req);
196 * If there is data to send, a packet is built in the given
197 * buffer and the size is returned. If there is no data to
198 * send, 0 is returned.
200 * Called with port_lock held.
203 gs_send_packet(struct gs_port *port, char *packet, unsigned size)
207 len = kfifo_len(&port->port_write_buf);
211 size = kfifo_out(&port->port_write_buf, packet, size);
218 * This function finds available write requests, calls
219 * gs_send_packet to fill these packets with data, and
220 * continues until either there are no more write requests
221 * available or no more data to send. This function is
222 * run whenever data arrives or write requests are available.
224 * Context: caller owns port_lock; port_usb is non-null.
226 static int gs_start_tx(struct gs_port *port)
228 __releases(&port->port_lock)
229 __acquires(&port->port_lock)
232 struct list_head *pool = &port->write_pool;
235 bool do_tty_wake = false;
240 in = port->port_usb->in;
242 while (!port->write_busy && !list_empty(pool)) {
243 struct usb_request *req;
246 if (port->write_started >= QUEUE_SIZE)
249 req = list_entry(pool->next, struct usb_request, list);
250 len = gs_send_packet(port, req->buf, in->maxpacket);
252 wake_up_interruptible(&port->drain_wait);
258 list_del(&req->list);
259 req->zero = kfifo_is_empty(&port->port_write_buf);
261 pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);
263 /* Drop lock while we call out of driver; completions
264 * could be issued while we do so. Disconnection may
265 * happen too; maybe immediately before we queue this!
267 * NOTE that we may keep sending data for a while after
268 * the TTY closed (dev->ioport->port_tty is NULL).
270 port->write_busy = true;
271 spin_unlock(&port->port_lock);
272 status = usb_ep_queue(in, req, GFP_ATOMIC);
273 spin_lock(&port->port_lock);
274 port->write_busy = false;
277 pr_debug("%s: %s %s err %d\n",
278 __func__, "queue", in->name, status);
279 list_add(&req->list, pool);
283 port->write_started++;
285 /* abort immediately after disconnect */
290 if (do_tty_wake && port->port.tty)
291 tty_wakeup(port->port.tty);
296 * Context: caller owns port_lock, and port_usb is set
298 static unsigned gs_start_rx(struct gs_port *port)
300 __releases(&port->port_lock)
301 __acquires(&port->port_lock)
304 struct list_head *pool = &port->read_pool;
305 struct usb_ep *out = port->port_usb->out;
307 while (!list_empty(pool)) {
308 struct usb_request *req;
310 struct tty_struct *tty;
312 /* no more rx if closed */
313 tty = port->port.tty;
317 if (port->read_started >= QUEUE_SIZE)
320 req = list_entry(pool->next, struct usb_request, list);
321 list_del(&req->list);
322 req->length = out->maxpacket;
324 /* drop lock while we call out; the controller driver
325 * may need to call us back (e.g. for disconnect)
327 spin_unlock(&port->port_lock);
328 status = usb_ep_queue(out, req, GFP_ATOMIC);
329 spin_lock(&port->port_lock);
332 pr_debug("%s: %s %s err %d\n",
333 __func__, "queue", out->name, status);
334 list_add(&req->list, pool);
337 port->read_started++;
339 /* abort immediately after disconnect */
343 return port->read_started;
347 * RX work takes data out of the RX queue and hands it up to the TTY
348 * layer until it refuses to take any more data (or is throttled back).
349 * Then it issues reads for any further data.
351 * If the RX queue becomes full enough that no usb_request is queued,
352 * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
353 * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
354 * can be buffered before the TTY layer's buffers (currently 64 KB).
356 static void gs_rx_push(struct work_struct *work)
358 struct delayed_work *w = to_delayed_work(work);
359 struct gs_port *port = container_of(w, struct gs_port, push);
360 struct tty_struct *tty;
361 struct list_head *queue = &port->read_queue;
362 bool disconnect = false;
363 bool do_push = false;
365 /* hand any queued data to the tty */
366 spin_lock_irq(&port->port_lock);
367 tty = port->port.tty;
368 while (!list_empty(queue)) {
369 struct usb_request *req;
371 req = list_first_entry(queue, struct usb_request, list);
373 /* leave data queued if tty was rx throttled */
374 if (tty && tty_throttled(tty))
377 switch (req->status) {
380 pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
384 /* presumably a transient fault */
385 pr_warn("ttyGS%d: unexpected RX status %d\n",
386 port->port_num, req->status);
389 /* normal completion */
393 /* push data to (open) tty */
394 if (req->actual && tty) {
395 char *packet = req->buf;
396 unsigned size = req->actual;
400 /* we may have pushed part of this packet already... */
407 count = tty_insert_flip_string(&port->port, packet,
412 /* stop pushing; TTY layer can't handle more */
413 port->n_read += count;
414 pr_vdebug("ttyGS%d: rx block %d/%d\n",
415 port->port_num, count, req->actual);
421 list_move(&req->list, &port->read_pool);
422 port->read_started--;
425 /* Push from tty to ldisc; this is handled by a workqueue,
426 * so we won't get callbacks and can hold port_lock
429 tty_flip_buffer_push(&port->port);
432 /* We want our data queue to become empty ASAP, keeping data
433 * in the tty and ldisc (not here). If we couldn't push any
434 * this time around, RX may be starved, so wait until next jiffy.
436 * We may leave non-empty queue only when there is a tty, and
437 * either it is throttled or there is no more room in flip buffer.
439 if (!list_empty(queue) && !tty_throttled(tty))
440 schedule_delayed_work(&port->push, 1);
442 /* If we're still connected, refill the USB RX queue. */
443 if (!disconnect && port->port_usb)
446 spin_unlock_irq(&port->port_lock);
449 static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
451 struct gs_port *port = ep->driver_data;
453 /* Queue all received data until the tty layer is ready for it. */
454 spin_lock(&port->port_lock);
455 list_add_tail(&req->list, &port->read_queue);
456 schedule_delayed_work(&port->push, 0);
457 spin_unlock(&port->port_lock);
460 static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
462 struct gs_port *port = ep->driver_data;
464 spin_lock(&port->port_lock);
465 list_add(&req->list, &port->write_pool);
466 port->write_started--;
468 switch (req->status) {
470 /* presumably a transient fault */
471 pr_warn("%s: unexpected %s status %d\n",
472 __func__, ep->name, req->status);
475 /* normal completion */
481 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
485 spin_unlock(&port->port_lock);
488 static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
491 struct usb_request *req;
493 while (!list_empty(head)) {
494 req = list_entry(head->next, struct usb_request, list);
495 list_del(&req->list);
496 gs_free_req(ep, req);
502 static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
503 void (*fn)(struct usb_ep *, struct usb_request *),
507 struct usb_request *req;
508 int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
510 /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
511 * do quite that many this time, don't fail ... we just won't
512 * be as speedy as we might otherwise be.
514 for (i = 0; i < n; i++) {
515 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
517 return list_empty(head) ? -ENOMEM : 0;
519 list_add_tail(&req->list, head);
527 * gs_start_io - start USB I/O streams
529 * Context: holding port_lock; port_tty and port_usb are non-null
531 * We only start I/O when something is connected to both sides of
532 * this port. If nothing is listening on the host side, we may
533 * be pointlessly filling up our TX buffers and FIFO.
535 static int gs_start_io(struct gs_port *port)
537 struct list_head *head = &port->read_pool;
538 struct usb_ep *ep = port->port_usb->out;
542 /* Allocate RX and TX I/O buffers. We can't easily do this much
543 * earlier (with GFP_KERNEL) because the requests are coupled to
544 * endpoints, as are the packet sizes we'll be using. Different
545 * configurations may use different endpoints with a given port;
546 * and high speed vs full speed changes packet sizes too.
548 status = gs_alloc_requests(ep, head, gs_read_complete,
549 &port->read_allocated);
553 status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
554 gs_write_complete, &port->write_allocated);
556 gs_free_requests(ep, head, &port->read_allocated);
560 /* queue read requests */
562 started = gs_start_rx(port);
566 /* Unblock any pending writes into our circular buffer, in case
567 * we didn't in gs_start_tx() */
568 tty_wakeup(port->port.tty);
570 gs_free_requests(ep, head, &port->read_allocated);
571 gs_free_requests(port->port_usb->in, &port->write_pool,
572 &port->write_allocated);
579 /*-------------------------------------------------------------------------*/
584 * gs_open sets up the link between a gs_port and its associated TTY.
585 * That link is broken *only* by TTY close(), and all driver methods
588 static int gs_open(struct tty_struct *tty, struct file *file)
590 int port_num = tty->index;
591 struct gs_port *port;
594 mutex_lock(&ports[port_num].lock);
595 port = ports[port_num].port;
601 spin_lock_irq(&port->port_lock);
603 /* allocate circular buffer on first open */
604 if (!kfifo_initialized(&port->port_write_buf)) {
606 spin_unlock_irq(&port->port_lock);
609 * portmaster's mutex still protects from simultaneous open(),
610 * and close() can't happen, yet.
613 status = kfifo_alloc(&port->port_write_buf,
614 WRITE_BUF_SIZE, GFP_KERNEL);
616 pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
617 port_num, tty, file);
621 spin_lock_irq(&port->port_lock);
624 /* already open? Great. */
625 if (port->port.count++)
626 goto exit_unlock_port;
628 tty->driver_data = port;
629 port->port.tty = tty;
631 /* if connected, start the I/O stream */
632 if (port->port_usb) {
633 /* if port is suspended, wait resume to start I/0 stream */
634 if (!port->suspended) {
635 struct gserial *gser = port->port_usb;
637 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
643 pr_debug("delay start of ttyGS%d\n", port->port_num);
644 port->start_delayed = true;
648 pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
651 spin_unlock_irq(&port->port_lock);
653 mutex_unlock(&ports[port_num].lock);
657 static int gs_close_flush_done(struct gs_port *p)
661 /* return true on disconnect or empty buffer or if raced with open() */
662 spin_lock_irq(&p->port_lock);
663 cond = p->port_usb == NULL || !kfifo_len(&p->port_write_buf) ||
665 spin_unlock_irq(&p->port_lock);
670 static void gs_close(struct tty_struct *tty, struct file *file)
672 struct gs_port *port = tty->driver_data;
673 struct gserial *gser;
675 spin_lock_irq(&port->port_lock);
677 if (port->port.count != 1) {
679 if (port->port.count == 0)
686 pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
688 gser = port->port_usb;
689 if (gser && !port->suspended && gser->disconnect)
690 gser->disconnect(gser);
692 /* wait for circular write buffer to drain, disconnect, or at
693 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
695 if (kfifo_len(&port->port_write_buf) > 0 && gser) {
696 spin_unlock_irq(&port->port_lock);
697 wait_event_interruptible_timeout(port->drain_wait,
698 gs_close_flush_done(port),
699 GS_CLOSE_TIMEOUT * HZ);
700 spin_lock_irq(&port->port_lock);
702 if (port->port.count != 1)
703 goto raced_with_open;
705 gser = port->port_usb;
708 /* Iff we're disconnected, there can be no I/O in flight so it's
709 * ok to free the circular buffer; else just scrub it. And don't
710 * let the push async work fire again until we're re-opened.
713 kfifo_free(&port->port_write_buf);
715 kfifo_reset(&port->port_write_buf);
717 port->start_delayed = false;
718 port->port.count = 0;
719 port->port.tty = NULL;
721 pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
722 port->port_num, tty, file);
724 wake_up(&port->close_wait);
726 spin_unlock_irq(&port->port_lock);
729 static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
731 struct gs_port *port = tty->driver_data;
734 pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
735 port->port_num, tty, count);
737 spin_lock_irqsave(&port->port_lock, flags);
739 count = kfifo_in(&port->port_write_buf, buf, count);
740 /* treat count == 0 as flush_chars() */
743 spin_unlock_irqrestore(&port->port_lock, flags);
748 static int gs_put_char(struct tty_struct *tty, unsigned char ch)
750 struct gs_port *port = tty->driver_data;
754 pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
755 port->port_num, tty, ch, __builtin_return_address(0));
757 spin_lock_irqsave(&port->port_lock, flags);
758 status = kfifo_put(&port->port_write_buf, ch);
759 spin_unlock_irqrestore(&port->port_lock, flags);
764 static void gs_flush_chars(struct tty_struct *tty)
766 struct gs_port *port = tty->driver_data;
769 pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
771 spin_lock_irqsave(&port->port_lock, flags);
774 spin_unlock_irqrestore(&port->port_lock, flags);
777 static unsigned int gs_write_room(struct tty_struct *tty)
779 struct gs_port *port = tty->driver_data;
781 unsigned int room = 0;
783 spin_lock_irqsave(&port->port_lock, flags);
785 room = kfifo_avail(&port->port_write_buf);
786 spin_unlock_irqrestore(&port->port_lock, flags);
788 pr_vdebug("gs_write_room: (%d,%p) room=%u\n",
789 port->port_num, tty, room);
794 static unsigned int gs_chars_in_buffer(struct tty_struct *tty)
796 struct gs_port *port = tty->driver_data;
800 spin_lock_irqsave(&port->port_lock, flags);
801 chars = kfifo_len(&port->port_write_buf);
802 spin_unlock_irqrestore(&port->port_lock, flags);
804 pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%u\n",
805 port->port_num, tty, chars);
810 /* undo side effects of setting TTY_THROTTLED */
811 static void gs_unthrottle(struct tty_struct *tty)
813 struct gs_port *port = tty->driver_data;
816 spin_lock_irqsave(&port->port_lock, flags);
817 if (port->port_usb) {
818 /* Kickstart read queue processing. We don't do xon/xoff,
819 * rts/cts, or other handshaking with the host, but if the
820 * read queue backs up enough we'll be NAKing OUT packets.
822 pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
823 schedule_delayed_work(&port->push, 0);
825 spin_unlock_irqrestore(&port->port_lock, flags);
828 static int gs_break_ctl(struct tty_struct *tty, int duration)
830 struct gs_port *port = tty->driver_data;
832 struct gserial *gser;
834 pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
835 port->port_num, duration);
837 spin_lock_irq(&port->port_lock);
838 gser = port->port_usb;
839 if (gser && gser->send_break)
840 status = gser->send_break(gser, duration);
841 spin_unlock_irq(&port->port_lock);
846 static const struct tty_operations gs_tty_ops = {
850 .put_char = gs_put_char,
851 .flush_chars = gs_flush_chars,
852 .write_room = gs_write_room,
853 .chars_in_buffer = gs_chars_in_buffer,
854 .unthrottle = gs_unthrottle,
855 .break_ctl = gs_break_ctl,
858 /*-------------------------------------------------------------------------*/
860 static struct tty_driver *gs_tty_driver;
862 #ifdef CONFIG_U_SERIAL_CONSOLE
864 static void gs_console_complete_out(struct usb_ep *ep, struct usb_request *req)
866 struct gs_console *cons = req->context;
868 switch (req->status) {
870 pr_warn("%s: unexpected %s status %d\n",
871 __func__, ep->name, req->status);
874 /* normal completion */
875 spin_lock(&cons->lock);
877 schedule_work(&cons->work);
878 spin_unlock(&cons->lock);
883 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
888 static void __gs_console_push(struct gs_console *cons)
890 struct usb_request *req = cons->req;
895 return; /* disconnected */
900 ep = cons->console.data;
901 size = kfifo_out(&cons->buf, req->buf, ep->maxpacket);
905 if (cons->missed && ep->maxpacket >= 64) {
909 len = sprintf(buf, "\n[missed %zu bytes]\n", cons->missed);
910 kfifo_in(&cons->buf, buf, len);
915 if (usb_ep_queue(ep, req, GFP_ATOMIC))
919 static void gs_console_work(struct work_struct *work)
921 struct gs_console *cons = container_of(work, struct gs_console, work);
923 spin_lock_irq(&cons->lock);
925 __gs_console_push(cons);
927 spin_unlock_irq(&cons->lock);
930 static void gs_console_write(struct console *co,
931 const char *buf, unsigned count)
933 struct gs_console *cons = container_of(co, struct gs_console, console);
937 spin_lock_irqsave(&cons->lock, flags);
939 n = kfifo_in(&cons->buf, buf, count);
941 cons->missed += count - n;
943 if (cons->req && !cons->req->length)
944 schedule_work(&cons->work);
946 spin_unlock_irqrestore(&cons->lock, flags);
949 static struct tty_driver *gs_console_device(struct console *co, int *index)
952 return gs_tty_driver;
955 static int gs_console_connect(struct gs_port *port)
957 struct gs_console *cons = port->console;
958 struct usb_request *req;
964 ep = port->port_usb->in;
965 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
968 req->complete = gs_console_complete_out;
972 spin_lock(&cons->lock);
974 cons->console.data = ep;
975 spin_unlock(&cons->lock);
977 pr_debug("ttyGS%d: console connected!\n", port->port_num);
979 schedule_work(&cons->work);
984 static void gs_console_disconnect(struct gs_port *port)
986 struct gs_console *cons = port->console;
987 struct usb_request *req;
993 spin_lock(&cons->lock);
996 ep = cons->console.data;
999 spin_unlock(&cons->lock);
1004 usb_ep_dequeue(ep, req);
1005 gs_free_req(ep, req);
1008 static int gs_console_init(struct gs_port *port)
1010 struct gs_console *cons;
1016 cons = kzalloc(sizeof(*port->console), GFP_KERNEL);
1020 strcpy(cons->console.name, "ttyGS");
1021 cons->console.write = gs_console_write;
1022 cons->console.device = gs_console_device;
1023 cons->console.flags = CON_PRINTBUFFER;
1024 cons->console.index = port->port_num;
1026 INIT_WORK(&cons->work, gs_console_work);
1027 spin_lock_init(&cons->lock);
1029 err = kfifo_alloc(&cons->buf, GS_CONSOLE_BUF_SIZE, GFP_KERNEL);
1031 pr_err("ttyGS%d: allocate console buffer failed\n", port->port_num);
1036 port->console = cons;
1037 register_console(&cons->console);
1039 spin_lock_irq(&port->port_lock);
1041 gs_console_connect(port);
1042 spin_unlock_irq(&port->port_lock);
1047 static void gs_console_exit(struct gs_port *port)
1049 struct gs_console *cons = port->console;
1054 unregister_console(&cons->console);
1056 spin_lock_irq(&port->port_lock);
1058 gs_console_disconnect(port);
1059 spin_unlock_irq(&port->port_lock);
1061 cancel_work_sync(&cons->work);
1062 kfifo_free(&cons->buf);
1064 port->console = NULL;
1067 ssize_t gserial_set_console(unsigned char port_num, const char *page, size_t count)
1069 struct gs_port *port;
1073 ret = strtobool(page, &enable);
1077 mutex_lock(&ports[port_num].lock);
1078 port = ports[port_num].port;
1080 if (WARN_ON(port == NULL)) {
1086 ret = gs_console_init(port);
1088 gs_console_exit(port);
1090 mutex_unlock(&ports[port_num].lock);
1092 return ret < 0 ? ret : count;
1094 EXPORT_SYMBOL_GPL(gserial_set_console);
1096 ssize_t gserial_get_console(unsigned char port_num, char *page)
1098 struct gs_port *port;
1101 mutex_lock(&ports[port_num].lock);
1102 port = ports[port_num].port;
1104 if (WARN_ON(port == NULL))
1107 ret = sprintf(page, "%u\n", !!port->console);
1109 mutex_unlock(&ports[port_num].lock);
1113 EXPORT_SYMBOL_GPL(gserial_get_console);
1117 static int gs_console_connect(struct gs_port *port)
1122 static void gs_console_disconnect(struct gs_port *port)
1126 static int gs_console_init(struct gs_port *port)
1131 static void gs_console_exit(struct gs_port *port)
1138 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1140 struct gs_port *port;
1143 mutex_lock(&ports[port_num].lock);
1144 if (ports[port_num].port) {
1149 port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1155 tty_port_init(&port->port);
1156 spin_lock_init(&port->port_lock);
1157 init_waitqueue_head(&port->drain_wait);
1158 init_waitqueue_head(&port->close_wait);
1160 INIT_DELAYED_WORK(&port->push, gs_rx_push);
1162 INIT_LIST_HEAD(&port->read_pool);
1163 INIT_LIST_HEAD(&port->read_queue);
1164 INIT_LIST_HEAD(&port->write_pool);
1166 port->port_num = port_num;
1167 port->port_line_coding = *coding;
1169 ports[port_num].port = port;
1171 mutex_unlock(&ports[port_num].lock);
1175 static int gs_closed(struct gs_port *port)
1179 spin_lock_irq(&port->port_lock);
1180 cond = port->port.count == 0;
1181 spin_unlock_irq(&port->port_lock);
1186 static void gserial_free_port(struct gs_port *port)
1188 cancel_delayed_work_sync(&port->push);
1189 /* wait for old opens to finish */
1190 wait_event(port->close_wait, gs_closed(port));
1191 WARN_ON(port->port_usb != NULL);
1192 tty_port_destroy(&port->port);
1196 void gserial_free_line(unsigned char port_num)
1198 struct gs_port *port;
1200 mutex_lock(&ports[port_num].lock);
1201 if (!ports[port_num].port) {
1202 mutex_unlock(&ports[port_num].lock);
1205 port = ports[port_num].port;
1206 gs_console_exit(port);
1207 ports[port_num].port = NULL;
1208 mutex_unlock(&ports[port_num].lock);
1210 gserial_free_port(port);
1211 tty_unregister_device(gs_tty_driver, port_num);
1213 EXPORT_SYMBOL_GPL(gserial_free_line);
1215 int gserial_alloc_line_no_console(unsigned char *line_num)
1217 struct usb_cdc_line_coding coding;
1218 struct gs_port *port;
1219 struct device *tty_dev;
1223 coding.dwDTERate = cpu_to_le32(9600);
1224 coding.bCharFormat = 8;
1225 coding.bParityType = USB_CDC_NO_PARITY;
1226 coding.bDataBits = USB_CDC_1_STOP_BITS;
1228 for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1229 ret = gs_port_alloc(port_num, &coding);
1239 /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1241 port = ports[port_num].port;
1242 tty_dev = tty_port_register_device(&port->port,
1243 gs_tty_driver, port_num, NULL);
1244 if (IS_ERR(tty_dev)) {
1245 pr_err("%s: failed to register tty for port %d, err %ld\n",
1246 __func__, port_num, PTR_ERR(tty_dev));
1248 ret = PTR_ERR(tty_dev);
1249 mutex_lock(&ports[port_num].lock);
1250 ports[port_num].port = NULL;
1251 mutex_unlock(&ports[port_num].lock);
1252 gserial_free_port(port);
1255 *line_num = port_num;
1259 EXPORT_SYMBOL_GPL(gserial_alloc_line_no_console);
1261 int gserial_alloc_line(unsigned char *line_num)
1263 int ret = gserial_alloc_line_no_console(line_num);
1265 if (!ret && !*line_num)
1266 gs_console_init(ports[*line_num].port);
1270 EXPORT_SYMBOL_GPL(gserial_alloc_line);
1273 * gserial_connect - notify TTY I/O glue that USB link is active
1274 * @gser: the function, set up with endpoints and descriptors
1275 * @port_num: which port is active
1276 * Context: any (usually from irq)
1278 * This is called activate endpoints and let the TTY layer know that
1279 * the connection is active ... not unlike "carrier detect". It won't
1280 * necessarily start I/O queues; unless the TTY is held open by any
1281 * task, there would be no point. However, the endpoints will be
1282 * activated so the USB host can perform I/O, subject to basic USB
1283 * hardware flow control.
1285 * Caller needs to have set up the endpoints and USB function in @dev
1286 * before calling this, as well as the appropriate (speed-specific)
1287 * endpoint descriptors, and also have allocate @port_num by calling
1288 * @gserial_alloc_line().
1290 * Returns negative errno or zero.
1291 * On success, ep->driver_data will be overwritten.
1293 int gserial_connect(struct gserial *gser, u8 port_num)
1295 struct gs_port *port;
1296 unsigned long flags;
1299 if (port_num >= MAX_U_SERIAL_PORTS)
1302 port = ports[port_num].port;
1304 pr_err("serial line %d not allocated.\n", port_num);
1307 if (port->port_usb) {
1308 pr_err("serial line %d is in use.\n", port_num);
1312 /* activate the endpoints */
1313 status = usb_ep_enable(gser->in);
1316 gser->in->driver_data = port;
1318 status = usb_ep_enable(gser->out);
1321 gser->out->driver_data = port;
1323 /* then tell the tty glue that I/O can work */
1324 spin_lock_irqsave(&port->port_lock, flags);
1325 gser->ioport = port;
1326 port->port_usb = gser;
1328 /* REVISIT unclear how best to handle this state...
1329 * we don't really couple it with the Linux TTY.
1331 gser->port_line_coding = port->port_line_coding;
1333 /* REVISIT if waiting on "carrier detect", signal. */
1335 /* if it's already open, start I/O ... and notify the serial
1336 * protocol about open/close status (connect/disconnect).
1338 if (port->port.count) {
1339 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1342 gser->connect(gser);
1344 if (gser->disconnect)
1345 gser->disconnect(gser);
1348 status = gs_console_connect(port);
1349 spin_unlock_irqrestore(&port->port_lock, flags);
1354 usb_ep_disable(gser->in);
1357 EXPORT_SYMBOL_GPL(gserial_connect);
1359 * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1360 * @gser: the function, on which gserial_connect() was called
1361 * Context: any (usually from irq)
1363 * This is called to deactivate endpoints and let the TTY layer know
1364 * that the connection went inactive ... not unlike "hangup".
1366 * On return, the state is as if gserial_connect() had never been called;
1367 * there is no active USB I/O on these endpoints.
1369 void gserial_disconnect(struct gserial *gser)
1371 struct gs_port *port = gser->ioport;
1372 unsigned long flags;
1377 /* tell the TTY glue not to do I/O here any more */
1378 spin_lock_irqsave(&port->port_lock, flags);
1380 gs_console_disconnect(port);
1382 /* REVISIT as above: how best to track this? */
1383 port->port_line_coding = gser->port_line_coding;
1385 port->port_usb = NULL;
1386 gser->ioport = NULL;
1387 if (port->port.count > 0) {
1388 wake_up_interruptible(&port->drain_wait);
1390 tty_hangup(port->port.tty);
1392 port->suspended = false;
1393 spin_unlock_irqrestore(&port->port_lock, flags);
1395 /* disable endpoints, aborting down any active I/O */
1396 usb_ep_disable(gser->out);
1397 usb_ep_disable(gser->in);
1399 /* finally, free any unused/unusable I/O buffers */
1400 spin_lock_irqsave(&port->port_lock, flags);
1401 if (port->port.count == 0)
1402 kfifo_free(&port->port_write_buf);
1403 gs_free_requests(gser->out, &port->read_pool, NULL);
1404 gs_free_requests(gser->out, &port->read_queue, NULL);
1405 gs_free_requests(gser->in, &port->write_pool, NULL);
1407 port->read_allocated = port->read_started =
1408 port->write_allocated = port->write_started = 0;
1410 spin_unlock_irqrestore(&port->port_lock, flags);
1412 EXPORT_SYMBOL_GPL(gserial_disconnect);
1414 void gserial_suspend(struct gserial *gser)
1416 struct gs_port *port = gser->ioport;
1417 unsigned long flags;
1419 spin_lock_irqsave(&port->port_lock, flags);
1420 port->suspended = true;
1421 spin_unlock_irqrestore(&port->port_lock, flags);
1423 EXPORT_SYMBOL_GPL(gserial_suspend);
1425 void gserial_resume(struct gserial *gser)
1427 struct gs_port *port = gser->ioport;
1428 unsigned long flags;
1430 spin_lock_irqsave(&port->port_lock, flags);
1431 port->suspended = false;
1432 if (!port->start_delayed) {
1433 spin_unlock_irqrestore(&port->port_lock, flags);
1437 pr_debug("delayed start ttyGS%d\n", port->port_num);
1440 gser->connect(gser);
1441 port->start_delayed = false;
1442 spin_unlock_irqrestore(&port->port_lock, flags);
1444 EXPORT_SYMBOL_GPL(gserial_resume);
1446 static int userial_init(void)
1451 gs_tty_driver = alloc_tty_driver(MAX_U_SERIAL_PORTS);
1455 gs_tty_driver->driver_name = "g_serial";
1456 gs_tty_driver->name = "ttyGS";
1457 /* uses dynamically assigned dev_t values */
1459 gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
1460 gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
1461 gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
1462 gs_tty_driver->init_termios = tty_std_termios;
1464 /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1465 * MS-Windows. Otherwise, most of these flags shouldn't affect
1466 * anything unless we were to actually hook up to a serial line.
1468 gs_tty_driver->init_termios.c_cflag =
1469 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1470 gs_tty_driver->init_termios.c_ispeed = 9600;
1471 gs_tty_driver->init_termios.c_ospeed = 9600;
1473 tty_set_operations(gs_tty_driver, &gs_tty_ops);
1474 for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1475 mutex_init(&ports[i].lock);
1477 /* export the driver ... */
1478 status = tty_register_driver(gs_tty_driver);
1480 pr_err("%s: cannot register, err %d\n",
1485 pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1487 (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1491 put_tty_driver(gs_tty_driver);
1492 gs_tty_driver = NULL;
1495 module_init(userial_init);
1497 static void userial_cleanup(void)
1499 tty_unregister_driver(gs_tty_driver);
1500 put_tty_driver(gs_tty_driver);
1501 gs_tty_driver = NULL;
1503 module_exit(userial_cleanup);
1505 MODULE_LICENSE("GPL");