3  * u_serial.c - utilities for USB gadget "serial port"/TTY support
39  * "serial port" functionality through the USB gadget stack.  Each such
40  * port is exposed through a /dev/ttyGS* node.
42  * After this module has been loaded, the individual TTY port can be requested
46  * host issues a config change event. Data can only flow when the port is
49  * A given TTY port can be made available in multiple configurations.
56  * Configurations may expose more than one TTY port.  For example, if
101  * The port structure holds info for each port, one for each minor number
105 	struct tty_port		port;  member
129 	bool			suspended;	/* port suspended */
139 	struct gs_port	*port;  member
210 gs_send_packet(struct gs_port *port, char *packet, unsigned size)  in gs_send_packet()  argument
214 	len = kfifo_len(&port->port_write_buf);  in gs_send_packet()
218 		size = kfifo_out(&port->port_write_buf, packet, size);  in gs_send_packet()
233 static int gs_start_tx(struct gs_port *port)  in gs_start_tx()  argument
235 __releases(&port->port_lock)  in gs_start_tx()
236 __acquires(&port->port_lock)  in gs_start_tx()
239 	struct list_head	*pool = &port->write_pool;  in gs_start_tx()
244 	if (!port->port_usb)  in gs_start_tx()
247 	in = port->port_usb->in;  in gs_start_tx()
249 	while (!port->write_busy && !list_empty(pool)) {  in gs_start_tx()
253 		if (port->write_started >= QUEUE_SIZE)  in gs_start_tx()
257 		len = gs_send_packet(port, req->buf, in->maxpacket);  in gs_start_tx()
259 			wake_up_interruptible(&port->drain_wait);  in gs_start_tx()
263 		port->icount.tx += len;  in gs_start_tx()
267 		req->zero = kfifo_is_empty(&port->port_write_buf);  in gs_start_tx()
269 		pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);  in gs_start_tx()
278 		port->write_busy = true;  in gs_start_tx()
279 		spin_unlock(&port->port_lock);  in gs_start_tx()
281 		spin_lock(&port->port_lock);  in gs_start_tx()
282 		port->write_busy = false;  in gs_start_tx()
291 		port->write_started++;  in gs_start_tx()
294 		if (!port->port_usb)  in gs_start_tx()
298 	if (do_tty_wake && port->port.tty)  in gs_start_tx()
299 		tty_wakeup(port->port.tty);  in gs_start_tx()
306 static unsigned gs_start_rx(struct gs_port *port)  in gs_start_rx()  argument
308 __releases(&port->port_lock)  in gs_start_rx()
309 __acquires(&port->port_lock)  in gs_start_rx()
312 	struct list_head	*pool = &port->read_pool;  in gs_start_rx()
313 	struct usb_ep		*out = port->port_usb->out;  in gs_start_rx()
321 		tty = port->port.tty;  in gs_start_rx()
325 		if (port->read_started >= QUEUE_SIZE)  in gs_start_rx()
335 		spin_unlock(&port->port_lock);  in gs_start_rx()
337 		spin_lock(&port->port_lock);  in gs_start_rx()
345 		port->read_started++;  in gs_start_rx()
348 		if (!port->port_usb)  in gs_start_rx()
351 	return port->read_started;  in gs_start_rx()
367 	struct gs_port		*port = container_of(w, struct gs_port, push);  in gs_rx_push()  local
369 	struct list_head	*queue = &port->read_queue;  in gs_rx_push()
374 	spin_lock_irq(&port->port_lock);  in gs_rx_push()
375 	tty = port->port.tty;  in gs_rx_push()
388 			pr_vdebug("ttyGS%d: shutdown\n", port->port_num);  in gs_rx_push()
394 				port->port_num, req->status);  in gs_rx_push()
409 			n = port->n_read;  in gs_rx_push()
415 			port->icount.rx += size;  in gs_rx_push()
416 			count = tty_insert_flip_string(&port->port, packet,  in gs_rx_push()
422 				port->n_read += count;  in gs_rx_push()
424 					  port->port_num, count, req->actual);  in gs_rx_push()
427 			port->n_read = 0;  in gs_rx_push()
430 		list_move(&req->list, &port->read_pool);  in gs_rx_push()
431 		port->read_started--;  in gs_rx_push()
438 		tty_flip_buffer_push(&port->port);  in gs_rx_push()
449 		schedule_delayed_work(&port->push, 1);  in gs_rx_push()
452 	if (!disconnect && port->port_usb)  in gs_rx_push()
453 		gs_start_rx(port);  in gs_rx_push()
455 	spin_unlock_irq(&port->port_lock);  in gs_rx_push()
460 	struct gs_port	*port = ep->driver_data;  in gs_read_complete()  local
463 	spin_lock(&port->port_lock);  in gs_read_complete()
464 	list_add_tail(&req->list, &port->read_queue);  in gs_read_complete()
465 	schedule_delayed_work(&port->push, 0);  in gs_read_complete()
466 	spin_unlock(&port->port_lock);  in gs_read_complete()
471 	struct gs_port	*port = ep->driver_data;  in gs_write_complete()  local
473 	spin_lock(&port->port_lock);  in gs_write_complete()
474 	list_add(&req->list, &port->write_pool);  in gs_write_complete()
475 	port->write_started--;  in gs_write_complete()
485 		gs_start_tx(port);  in gs_write_complete()
494 	spin_unlock(&port->port_lock);  in gs_write_complete()
537  * @port: port to use
541  * this port.  If nothing is listening on the host side, we may
544 static int gs_start_io(struct gs_port *port)  in gs_start_io()  argument
546 	struct list_head	*head = &port->read_pool;  in gs_start_io()
551 	if (!port->port_usb || !port->port.tty)  in gs_start_io()
557 	 * configurations may use different endpoints with a given port;  in gs_start_io()
560 	ep = port->port_usb->out;  in gs_start_io()
562 		&port->read_allocated);  in gs_start_io()
566 	status = gs_alloc_requests(port->port_usb->in, &port->write_pool,  in gs_start_io()
567 			gs_write_complete, &port->write_allocated);  in gs_start_io()
569 		gs_free_requests(ep, head, &port->read_allocated);  in gs_start_io()
574 	port->n_read = 0;  in gs_start_io()
575 	started = gs_start_rx(port);  in gs_start_io()
578 		gs_start_tx(port);  in gs_start_io()
581 		tty_wakeup(port->port.tty);  in gs_start_io()
584 		if (port->port_usb) {  in gs_start_io()
585 			gs_free_requests(ep, head, &port->read_allocated);  in gs_start_io()
586 			gs_free_requests(port->port_usb->in, &port->write_pool,  in gs_start_io()
587 				&port->write_allocated);  in gs_start_io()
607 	struct gs_port	*port;  in gs_open()  local
611 	port = ports[port_num].port;  in gs_open()
612 	if (!port) {  in gs_open()
617 	spin_lock_irq(&port->port_lock);  in gs_open()
620 	if (!kfifo_initialized(&port->port_write_buf)) {  in gs_open()
622 		spin_unlock_irq(&port->port_lock);  in gs_open()
629 		status = kfifo_alloc(&port->port_write_buf,  in gs_open()
637 		spin_lock_irq(&port->port_lock);  in gs_open()
641 	if (port->port.count++)  in gs_open()
644 	tty->driver_data = port;  in gs_open()
645 	port->port.tty = tty;  in gs_open()
648 	if (port->port_usb) {  in gs_open()
649 		/* if port is suspended, wait resume to start I/0 stream */  in gs_open()
650 		if (!port->suspended) {  in gs_open()
651 			struct gserial	*gser = port->port_usb;  in gs_open()
653 			pr_debug("gs_open: start ttyGS%d\n", port->port_num);  in gs_open()
654 			gs_start_io(port);  in gs_open()
659 			pr_debug("delay start of ttyGS%d\n", port->port_num);  in gs_open()
660 			port->start_delayed = true;  in gs_open()
664 	pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);  in gs_open()
667 	spin_unlock_irq(&port->port_lock);  in gs_open()
680 		p->port.count > 1;  in gs_close_flush_done()
688 	struct gs_port *port = tty->driver_data;  in gs_close()  local
691 	spin_lock_irq(&port->port_lock);  in gs_close()
693 	if (port->port.count != 1) {  in gs_close()
695 		if (port->port.count == 0)  in gs_close()
698 			--port->port.count;  in gs_close()
702 	pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);  in gs_close()
704 	gser = port->port_usb;  in gs_close()
705 	if (gser && !port->suspended && gser->disconnect)  in gs_close()
711 	if (kfifo_len(&port->port_write_buf) > 0 && gser) {  in gs_close()
712 		spin_unlock_irq(&port->port_lock);  in gs_close()
713 		wait_event_interruptible_timeout(port->drain_wait,  in gs_close()
714 					gs_close_flush_done(port),  in gs_close()
716 		spin_lock_irq(&port->port_lock);  in gs_close()
718 		if (port->port.count != 1)  in gs_close()
721 		gser = port->port_usb;  in gs_close()
729 		kfifo_free(&port->port_write_buf);  in gs_close()
731 		kfifo_reset(&port->port_write_buf);  in gs_close()
733 	port->start_delayed = false;  in gs_close()
734 	port->port.count = 0;  in gs_close()
735 	port->port.tty = NULL;  in gs_close()
738 			port->port_num, tty, file);  in gs_close()
740 	wake_up(&port->close_wait);  in gs_close()
742 	spin_unlock_irq(&port->port_lock);  in gs_close()
747 	struct gs_port	*port = tty->driver_data;  in gs_write()  local
751 			port->port_num, tty, count);  in gs_write()
753 	spin_lock_irqsave(&port->port_lock, flags);  in gs_write()
755 		count = kfifo_in(&port->port_write_buf, buf, count);  in gs_write()
757 	if (port->port_usb)  in gs_write()
758 		gs_start_tx(port);  in gs_write()
759 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_write()
766 	struct gs_port	*port = tty->driver_data;  in gs_put_char()  local
771 		port->port_num, tty, ch, __builtin_return_address(0));  in gs_put_char()
773 	spin_lock_irqsave(&port->port_lock, flags);  in gs_put_char()
774 	status = kfifo_put(&port->port_write_buf, ch);  in gs_put_char()
775 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_put_char()
782 	struct gs_port	*port = tty->driver_data;  in gs_flush_chars()  local
785 	pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);  in gs_flush_chars()
787 	spin_lock_irqsave(&port->port_lock, flags);  in gs_flush_chars()
788 	if (port->port_usb)  in gs_flush_chars()
789 		gs_start_tx(port);  in gs_flush_chars()
790 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_flush_chars()
795 	struct gs_port	*port = tty->driver_data;  in gs_write_room()  local
799 	spin_lock_irqsave(&port->port_lock, flags);  in gs_write_room()
800 	if (port->port_usb)  in gs_write_room()
801 		room = kfifo_avail(&port->port_write_buf);  in gs_write_room()
802 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_write_room()
805 		port->port_num, tty, room);  in gs_write_room()
812 	struct gs_port	*port = tty->driver_data;  in gs_chars_in_buffer()  local
816 	spin_lock_irqsave(&port->port_lock, flags);  in gs_chars_in_buffer()
817 	chars = kfifo_len(&port->port_write_buf);  in gs_chars_in_buffer()
818 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_chars_in_buffer()
821 		port->port_num, tty, chars);  in gs_chars_in_buffer()
829 	struct gs_port		*port = tty->driver_data;  in gs_unthrottle()  local
832 	spin_lock_irqsave(&port->port_lock, flags);  in gs_unthrottle()
833 	if (port->port_usb) {  in gs_unthrottle()
838 		pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);  in gs_unthrottle()
839 		schedule_delayed_work(&port->push, 0);  in gs_unthrottle()
841 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_unthrottle()
846 	struct gs_port	*port = tty->driver_data;  in gs_break_ctl()  local
851 			port->port_num, duration);  in gs_break_ctl()
853 	spin_lock_irq(&port->port_lock);  in gs_break_ctl()
854 	gser = port->port_usb;  in gs_break_ctl()
857 	spin_unlock_irq(&port->port_lock);  in gs_break_ctl()
865 	struct gs_port *port = tty->driver_data;  in gs_get_icount()  local
869 	spin_lock_irqsave(&port->port_lock, flags);  in gs_get_icount()
870 	cnow = port->icount;  in gs_get_icount()
871 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_get_icount()
992 static int gs_console_connect(struct gs_port *port)  in gs_console_connect()  argument
994 	struct gs_console *cons = port->console;  in gs_console_connect()
1001 	ep = port->port_usb->in;  in gs_console_connect()
1014 	pr_debug("ttyGS%d: console connected!\n", port->port_num);  in gs_console_connect()
1021 static void gs_console_disconnect(struct gs_port *port)  in gs_console_disconnect()  argument
1023 	struct gs_console *cons = port->console;  in gs_console_disconnect()
1045 static int gs_console_init(struct gs_port *port)  in gs_console_init()  argument
1050 	if (port->console)  in gs_console_init()
1053 	cons = kzalloc(sizeof(*port->console), GFP_KERNEL);  in gs_console_init()
1061 	cons->console.index = port->port_num;  in gs_console_init()
1068 		pr_err("ttyGS%d: allocate console buffer failed\n", port->port_num);  in gs_console_init()
1073 	port->console = cons;  in gs_console_init()
1076 	spin_lock_irq(&port->port_lock);  in gs_console_init()
1077 	if (port->port_usb)  in gs_console_init()
1078 		gs_console_connect(port);  in gs_console_init()
1079 	spin_unlock_irq(&port->port_lock);  in gs_console_init()
1084 static void gs_console_exit(struct gs_port *port)  in gs_console_exit()  argument
1086 	struct gs_console *cons = port->console;  in gs_console_exit()
1093 	spin_lock_irq(&port->port_lock);  in gs_console_exit()
1095 		gs_console_disconnect(port);  in gs_console_exit()
1096 	spin_unlock_irq(&port->port_lock);  in gs_console_exit()
1101 	port->console = NULL;  in gs_console_exit()
1106 	struct gs_port *port;  in gserial_set_console()  local
1115 	port = ports[port_num].port;  in gserial_set_console()
1117 	if (WARN_ON(port == NULL)) {  in gserial_set_console()
1123 		ret = gs_console_init(port);  in gserial_set_console()
1125 		gs_console_exit(port);  in gserial_set_console()
1135 	struct gs_port *port;  in gserial_get_console()  local
1139 	port = ports[port_num].port;  in gserial_get_console()
1141 	if (WARN_ON(port == NULL))  in gserial_get_console()
1144 		ret = sprintf(page, "%u\n", !!port->console);  in gserial_get_console()
1154 static int gs_console_connect(struct gs_port *port)  in gs_console_connect()  argument
1159 static void gs_console_disconnect(struct gs_port *port)  in gs_console_disconnect()  argument
1163 static int gs_console_init(struct gs_port *port)  in gs_console_init()  argument
1168 static void gs_console_exit(struct gs_port *port)  in gs_console_exit()  argument
1177 	struct gs_port	*port;  in gs_port_alloc()  local
1181 	if (ports[port_num].port) {  in gs_port_alloc()
1186 	port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);  in gs_port_alloc()
1187 	if (port == NULL) {  in gs_port_alloc()
1192 	tty_port_init(&port->port);  in gs_port_alloc()
1193 	spin_lock_init(&port->port_lock);  in gs_port_alloc()
1194 	init_waitqueue_head(&port->drain_wait);  in gs_port_alloc()
1195 	init_waitqueue_head(&port->close_wait);  in gs_port_alloc()
1197 	INIT_DELAYED_WORK(&port->push, gs_rx_push);  in gs_port_alloc()
1199 	INIT_LIST_HEAD(&port->read_pool);  in gs_port_alloc()
1200 	INIT_LIST_HEAD(&port->read_queue);  in gs_port_alloc()
1201 	INIT_LIST_HEAD(&port->write_pool);  in gs_port_alloc()
1203 	port->port_num = port_num;  in gs_port_alloc()
1204 	port->port_line_coding = *coding;  in gs_port_alloc()
1206 	ports[port_num].port = port;  in gs_port_alloc()
1212 static int gs_closed(struct gs_port *port)  in gs_closed()  argument
1216 	spin_lock_irq(&port->port_lock);  in gs_closed()
1217 	cond = port->port.count == 0;  in gs_closed()
1218 	spin_unlock_irq(&port->port_lock);  in gs_closed()
1223 static void gserial_free_port(struct gs_port *port)  in gserial_free_port()  argument
1225 	cancel_delayed_work_sync(&port->push);  in gserial_free_port()
1227 	wait_event(port->close_wait, gs_closed(port));  in gserial_free_port()
1228 	WARN_ON(port->port_usb != NULL);  in gserial_free_port()
1229 	tty_port_destroy(&port->port);  in gserial_free_port()
1230 	kfree(port);  in gserial_free_port()
1235 	struct gs_port	*port;  in gserial_free_line()  local
1238 	if (!ports[port_num].port) {  in gserial_free_line()
1242 	port = ports[port_num].port;  in gserial_free_line()
1243 	gs_console_exit(port);  in gserial_free_line()
1244 	ports[port_num].port = NULL;  in gserial_free_line()
1247 	gserial_free_port(port);  in gserial_free_line()
1255 	struct gs_port			*port;  in gserial_alloc_line_no_console()  local
1278 	port = ports[port_num].port;  in gserial_alloc_line_no_console()
1279 	tty_dev = tty_port_register_device(&port->port,  in gserial_alloc_line_no_console()
1282 		pr_err("%s: failed to register tty for port %d, err %ld\n",  in gserial_alloc_line_no_console()
1287 		ports[port_num].port = NULL;  in gserial_alloc_line_no_console()
1289 		gserial_free_port(port);  in gserial_alloc_line_no_console()
1303 		gs_console_init(ports[*line_num].port);  in gserial_alloc_line()
1312  * @port_num: which port is active
1332 	struct gs_port	*port;  in gserial_connect()  local
1339 	port = ports[port_num].port;  in gserial_connect()
1340 	if (!port) {  in gserial_connect()
1344 	if (port->port_usb) {  in gserial_connect()
1353 	gser->in->driver_data = port;  in gserial_connect()
1358 	gser->out->driver_data = port;  in gserial_connect()
1361 	spin_lock_irqsave(&port->port_lock, flags);  in gserial_connect()
1362 	gser->ioport = port;  in gserial_connect()
1363 	port->port_usb = gser;  in gserial_connect()
1368 	gser->port_line_coding = port->port_line_coding;  in gserial_connect()
1375 	if (port->port.count) {  in gserial_connect()
1376 		pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);  in gserial_connect()
1377 		gs_start_io(port);  in gserial_connect()
1385 	status = gs_console_connect(port);  in gserial_connect()
1386 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_connect()
1408 	struct gs_port	*port = gser->ioport;  in gserial_disconnect()  local
1411 	if (!port)  in gserial_disconnect()
1417 	spin_lock(&port->port_lock);  in gserial_disconnect()
1419 	gs_console_disconnect(port);  in gserial_disconnect()
1422 	port->port_line_coding = gser->port_line_coding;  in gserial_disconnect()
1424 	port->port_usb = NULL;  in gserial_disconnect()
1426 	if (port->port.count > 0) {  in gserial_disconnect()
1427 		wake_up_interruptible(&port->drain_wait);  in gserial_disconnect()
1428 		if (port->port.tty)  in gserial_disconnect()
1429 			tty_hangup(port->port.tty);  in gserial_disconnect()
1431 	port->suspended = false;  in gserial_disconnect()
1432 	spin_unlock(&port->port_lock);  in gserial_disconnect()
1440 	spin_lock_irqsave(&port->port_lock, flags);  in gserial_disconnect()
1441 	if (port->port.count == 0)  in gserial_disconnect()
1442 		kfifo_free(&port->port_write_buf);  in gserial_disconnect()
1443 	gs_free_requests(gser->out, &port->read_pool, NULL);  in gserial_disconnect()
1444 	gs_free_requests(gser->out, &port->read_queue, NULL);  in gserial_disconnect()
1445 	gs_free_requests(gser->in, &port->write_pool, NULL);  in gserial_disconnect()
1447 	port->read_allocated = port->read_started =  in gserial_disconnect()
1448 		port->write_allocated = port->write_started = 0;  in gserial_disconnect()
1450 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_disconnect()
1456 	struct gs_port	*port;  in gserial_suspend()  local
1460 	port = gser->ioport;  in gserial_suspend()
1462 	if (!port) {  in gserial_suspend()
1467 	spin_lock(&port->port_lock);  in gserial_suspend()
1469 	port->suspended = true;  in gserial_suspend()
1470 	port->start_delayed = true;  in gserial_suspend()
1471 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_suspend()
1477 	struct gs_port *port;  in gserial_resume()  local
1481 	port = gser->ioport;  in gserial_resume()
1483 	if (!port) {  in gserial_resume()
1488 	spin_lock(&port->port_lock);  in gserial_resume()
1490 	port->suspended = false;  in gserial_resume()
1491 	if (!port->start_delayed) {  in gserial_resume()
1492 		spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_resume()
1496 	pr_debug("delayed start ttyGS%d\n", port->port_num);  in gserial_resume()
1497 	gs_start_io(port);  in gserial_resume()
1500 	port->start_delayed = false;  in gserial_resume()
1501 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_resume()
1566 MODULE_DESCRIPTION("utilities for USB gadget \"serial port\"/TTY support");