3  * u_serial.c - utilities for USB gadget "serial port"/TTY support
37  * "serial port" functionality through the USB gadget stack.  Each such
38  * port is exposed through a /dev/ttyGS* node.
40  * After this module has been loaded, the individual TTY port can be requested
44  * host issues a config change event. Data can only flow when the port is
47  * A given TTY port can be made available in multiple configurations.
54  * Configurations may expose more than one TTY port.  For example, if
99  * The port structure holds info for each port, one for each minor number
103 	struct tty_port		port;  member
127 	bool			suspended;	/* port suspended */
136 	struct gs_port	*port;  member
207 gs_send_packet(struct gs_port *port, char *packet, unsigned size)  in gs_send_packet()  argument
211 	len = kfifo_len(&port->port_write_buf);  in gs_send_packet()
215 		size = kfifo_out(&port->port_write_buf, packet, size);  in gs_send_packet()
230 static int gs_start_tx(struct gs_port *port)  in gs_start_tx()  argument
232 __releases(&port->port_lock)  in gs_start_tx()
233 __acquires(&port->port_lock)  in gs_start_tx()
236 	struct list_head	*pool = &port->write_pool;  in gs_start_tx()
241 	if (!port->port_usb)  in gs_start_tx()
244 	in = port->port_usb->in;  in gs_start_tx()
246 	while (!port->write_busy && !list_empty(pool)) {  in gs_start_tx()
250 		if (port->write_started >= QUEUE_SIZE)  in gs_start_tx()
254 		len = gs_send_packet(port, req->buf, in->maxpacket);  in gs_start_tx()
256 			wake_up_interruptible(&port->drain_wait);  in gs_start_tx()
263 		req->zero = kfifo_is_empty(&port->port_write_buf);  in gs_start_tx()
265 		pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);  in gs_start_tx()
274 		port->write_busy = true;  in gs_start_tx()
275 		spin_unlock(&port->port_lock);  in gs_start_tx()
277 		spin_lock(&port->port_lock);  in gs_start_tx()
278 		port->write_busy = false;  in gs_start_tx()
287 		port->write_started++;  in gs_start_tx()
290 		if (!port->port_usb)  in gs_start_tx()
294 	if (do_tty_wake && port->port.tty)  in gs_start_tx()
295 		tty_wakeup(port->port.tty);  in gs_start_tx()
302 static unsigned gs_start_rx(struct gs_port *port)  in gs_start_rx()  argument
304 __releases(&port->port_lock)  in gs_start_rx()
305 __acquires(&port->port_lock)  in gs_start_rx()
308 	struct list_head	*pool = &port->read_pool;  in gs_start_rx()
309 	struct usb_ep		*out = port->port_usb->out;  in gs_start_rx()
317 		tty = port->port.tty;  in gs_start_rx()
321 		if (port->read_started >= QUEUE_SIZE)  in gs_start_rx()
331 		spin_unlock(&port->port_lock);  in gs_start_rx()
333 		spin_lock(&port->port_lock);  in gs_start_rx()
341 		port->read_started++;  in gs_start_rx()
344 		if (!port->port_usb)  in gs_start_rx()
347 	return port->read_started;  in gs_start_rx()
363 	struct gs_port		*port = container_of(w, struct gs_port, push);  in gs_rx_push()  local
365 	struct list_head	*queue = &port->read_queue;  in gs_rx_push()
370 	spin_lock_irq(&port->port_lock);  in gs_rx_push()
371 	tty = port->port.tty;  in gs_rx_push()
384 			pr_vdebug("ttyGS%d: shutdown\n", port->port_num);  in gs_rx_push()
390 				port->port_num, req->status);  in gs_rx_push()
405 			n = port->n_read;  in gs_rx_push()
411 			count = tty_insert_flip_string(&port->port, packet,  in gs_rx_push()
417 				port->n_read += count;  in gs_rx_push()
419 					  port->port_num, count, req->actual);  in gs_rx_push()
422 			port->n_read = 0;  in gs_rx_push()
425 		list_move(&req->list, &port->read_pool);  in gs_rx_push()
426 		port->read_started--;  in gs_rx_push()
433 		tty_flip_buffer_push(&port->port);  in gs_rx_push()
444 		schedule_delayed_work(&port->push, 1);  in gs_rx_push()
447 	if (!disconnect && port->port_usb)  in gs_rx_push()
448 		gs_start_rx(port);  in gs_rx_push()
450 	spin_unlock_irq(&port->port_lock);  in gs_rx_push()
455 	struct gs_port	*port = ep->driver_data;  in gs_read_complete()  local
458 	spin_lock(&port->port_lock);  in gs_read_complete()
459 	list_add_tail(&req->list, &port->read_queue);  in gs_read_complete()
460 	schedule_delayed_work(&port->push, 0);  in gs_read_complete()
461 	spin_unlock(&port->port_lock);  in gs_read_complete()
466 	struct gs_port	*port = ep->driver_data;  in gs_write_complete()  local
468 	spin_lock(&port->port_lock);  in gs_write_complete()
469 	list_add(&req->list, &port->write_pool);  in gs_write_complete()
470 	port->write_started--;  in gs_write_complete()
480 		gs_start_tx(port);  in gs_write_complete()
489 	spin_unlock(&port->port_lock);  in gs_write_complete()
532  * @port: port to use
536  * this port.  If nothing is listening on the host side, we may
539 static int gs_start_io(struct gs_port *port)  in gs_start_io()  argument
541 	struct list_head	*head = &port->read_pool;  in gs_start_io()
546 	if (!port->port_usb || !port->port.tty)  in gs_start_io()
552 	 * configurations may use different endpoints with a given port;  in gs_start_io()
555 	ep = port->port_usb->out;  in gs_start_io()
557 		&port->read_allocated);  in gs_start_io()
561 	status = gs_alloc_requests(port->port_usb->in, &port->write_pool,  in gs_start_io()
562 			gs_write_complete, &port->write_allocated);  in gs_start_io()
564 		gs_free_requests(ep, head, &port->read_allocated);  in gs_start_io()
569 	port->n_read = 0;  in gs_start_io()
570 	started = gs_start_rx(port);  in gs_start_io()
573 		gs_start_tx(port);  in gs_start_io()
576 		tty_wakeup(port->port.tty);  in gs_start_io()
579 		if (port->port_usb) {  in gs_start_io()
580 			gs_free_requests(ep, head, &port->read_allocated);  in gs_start_io()
581 			gs_free_requests(port->port_usb->in, &port->write_pool,  in gs_start_io()
582 				&port->write_allocated);  in gs_start_io()
602 	struct gs_port	*port;  in gs_open()  local
606 	port = ports[port_num].port;  in gs_open()
607 	if (!port) {  in gs_open()
612 	spin_lock_irq(&port->port_lock);  in gs_open()
615 	if (!kfifo_initialized(&port->port_write_buf)) {  in gs_open()
617 		spin_unlock_irq(&port->port_lock);  in gs_open()
624 		status = kfifo_alloc(&port->port_write_buf,  in gs_open()
632 		spin_lock_irq(&port->port_lock);  in gs_open()
636 	if (port->port.count++)  in gs_open()
639 	tty->driver_data = port;  in gs_open()
640 	port->port.tty = tty;  in gs_open()
643 	if (port->port_usb) {  in gs_open()
644 		/* if port is suspended, wait resume to start I/0 stream */  in gs_open()
645 		if (!port->suspended) {  in gs_open()
646 			struct gserial	*gser = port->port_usb;  in gs_open()
648 			pr_debug("gs_open: start ttyGS%d\n", port->port_num);  in gs_open()
649 			gs_start_io(port);  in gs_open()
654 			pr_debug("delay start of ttyGS%d\n", port->port_num);  in gs_open()
655 			port->start_delayed = true;  in gs_open()
659 	pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);  in gs_open()
662 	spin_unlock_irq(&port->port_lock);  in gs_open()
675 		p->port.count > 1;  in gs_close_flush_done()
683 	struct gs_port *port = tty->driver_data;  in gs_close()  local
686 	spin_lock_irq(&port->port_lock);  in gs_close()
688 	if (port->port.count != 1) {  in gs_close()
690 		if (port->port.count == 0)  in gs_close()
693 			--port->port.count;  in gs_close()
697 	pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);  in gs_close()
699 	gser = port->port_usb;  in gs_close()
700 	if (gser && !port->suspended && gser->disconnect)  in gs_close()
706 	if (kfifo_len(&port->port_write_buf) > 0 && gser) {  in gs_close()
707 		spin_unlock_irq(&port->port_lock);  in gs_close()
708 		wait_event_interruptible_timeout(port->drain_wait,  in gs_close()
709 					gs_close_flush_done(port),  in gs_close()
711 		spin_lock_irq(&port->port_lock);  in gs_close()
713 		if (port->port.count != 1)  in gs_close()
716 		gser = port->port_usb;  in gs_close()
724 		kfifo_free(&port->port_write_buf);  in gs_close()
726 		kfifo_reset(&port->port_write_buf);  in gs_close()
728 	port->start_delayed = false;  in gs_close()
729 	port->port.count = 0;  in gs_close()
730 	port->port.tty = NULL;  in gs_close()
733 			port->port_num, tty, file);  in gs_close()
735 	wake_up(&port->close_wait);  in gs_close()
737 	spin_unlock_irq(&port->port_lock);  in gs_close()
742 	struct gs_port	*port = tty->driver_data;  in gs_write()  local
746 			port->port_num, tty, count);  in gs_write()
748 	spin_lock_irqsave(&port->port_lock, flags);  in gs_write()
750 		count = kfifo_in(&port->port_write_buf, buf, count);  in gs_write()
752 	if (port->port_usb)  in gs_write()
753 		gs_start_tx(port);  in gs_write()
754 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_write()
761 	struct gs_port	*port = tty->driver_data;  in gs_put_char()  local
766 		port->port_num, tty, ch, __builtin_return_address(0));  in gs_put_char()
768 	spin_lock_irqsave(&port->port_lock, flags);  in gs_put_char()
769 	status = kfifo_put(&port->port_write_buf, ch);  in gs_put_char()
770 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_put_char()
777 	struct gs_port	*port = tty->driver_data;  in gs_flush_chars()  local
780 	pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);  in gs_flush_chars()
782 	spin_lock_irqsave(&port->port_lock, flags);  in gs_flush_chars()
783 	if (port->port_usb)  in gs_flush_chars()
784 		gs_start_tx(port);  in gs_flush_chars()
785 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_flush_chars()
790 	struct gs_port	*port = tty->driver_data;  in gs_write_room()  local
794 	spin_lock_irqsave(&port->port_lock, flags);  in gs_write_room()
795 	if (port->port_usb)  in gs_write_room()
796 		room = kfifo_avail(&port->port_write_buf);  in gs_write_room()
797 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_write_room()
800 		port->port_num, tty, room);  in gs_write_room()
807 	struct gs_port	*port = tty->driver_data;  in gs_chars_in_buffer()  local
811 	spin_lock_irqsave(&port->port_lock, flags);  in gs_chars_in_buffer()
812 	chars = kfifo_len(&port->port_write_buf);  in gs_chars_in_buffer()
813 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_chars_in_buffer()
816 		port->port_num, tty, chars);  in gs_chars_in_buffer()
824 	struct gs_port		*port = tty->driver_data;  in gs_unthrottle()  local
827 	spin_lock_irqsave(&port->port_lock, flags);  in gs_unthrottle()
828 	if (port->port_usb) {  in gs_unthrottle()
833 		pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);  in gs_unthrottle()
834 		schedule_delayed_work(&port->push, 0);  in gs_unthrottle()
836 	spin_unlock_irqrestore(&port->port_lock, flags);  in gs_unthrottle()
841 	struct gs_port	*port = tty->driver_data;  in gs_break_ctl()  local
846 			port->port_num, duration);  in gs_break_ctl()
848 	spin_lock_irq(&port->port_lock);  in gs_break_ctl()
849 	gser = port->port_usb;  in gs_break_ctl()
852 	spin_unlock_irq(&port->port_lock);  in gs_break_ctl()
969 static int gs_console_connect(struct gs_port *port)  in gs_console_connect()  argument
971 	struct gs_console *cons = port->console;  in gs_console_connect()
978 	ep = port->port_usb->in;  in gs_console_connect()
991 	pr_debug("ttyGS%d: console connected!\n", port->port_num);  in gs_console_connect()
998 static void gs_console_disconnect(struct gs_port *port)  in gs_console_disconnect()  argument
1000 	struct gs_console *cons = port->console;  in gs_console_disconnect()
1022 static int gs_console_init(struct gs_port *port)  in gs_console_init()  argument
1027 	if (port->console)  in gs_console_init()
1030 	cons = kzalloc(sizeof(*port->console), GFP_KERNEL);  in gs_console_init()
1038 	cons->console.index = port->port_num;  in gs_console_init()
1045 		pr_err("ttyGS%d: allocate console buffer failed\n", port->port_num);  in gs_console_init()
1050 	port->console = cons;  in gs_console_init()
1053 	spin_lock_irq(&port->port_lock);  in gs_console_init()
1054 	if (port->port_usb)  in gs_console_init()
1055 		gs_console_connect(port);  in gs_console_init()
1056 	spin_unlock_irq(&port->port_lock);  in gs_console_init()
1061 static void gs_console_exit(struct gs_port *port)  in gs_console_exit()  argument
1063 	struct gs_console *cons = port->console;  in gs_console_exit()
1070 	spin_lock_irq(&port->port_lock);  in gs_console_exit()
1072 		gs_console_disconnect(port);  in gs_console_exit()
1073 	spin_unlock_irq(&port->port_lock);  in gs_console_exit()
1078 	port->console = NULL;  in gs_console_exit()
1083 	struct gs_port *port;  in gserial_set_console()  local
1092 	port = ports[port_num].port;  in gserial_set_console()
1094 	if (WARN_ON(port == NULL)) {  in gserial_set_console()
1100 		ret = gs_console_init(port);  in gserial_set_console()
1102 		gs_console_exit(port);  in gserial_set_console()
1112 	struct gs_port *port;  in gserial_get_console()  local
1116 	port = ports[port_num].port;  in gserial_get_console()
1118 	if (WARN_ON(port == NULL))  in gserial_get_console()
1121 		ret = sprintf(page, "%u\n", !!port->console);  in gserial_get_console()
1131 static int gs_console_connect(struct gs_port *port)  in gs_console_connect()  argument
1136 static void gs_console_disconnect(struct gs_port *port)  in gs_console_disconnect()  argument
1140 static int gs_console_init(struct gs_port *port)  in gs_console_init()  argument
1145 static void gs_console_exit(struct gs_port *port)  in gs_console_exit()  argument
1154 	struct gs_port	*port;  in gs_port_alloc()  local
1158 	if (ports[port_num].port) {  in gs_port_alloc()
1163 	port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);  in gs_port_alloc()
1164 	if (port == NULL) {  in gs_port_alloc()
1169 	tty_port_init(&port->port);  in gs_port_alloc()
1170 	spin_lock_init(&port->port_lock);  in gs_port_alloc()
1171 	init_waitqueue_head(&port->drain_wait);  in gs_port_alloc()
1172 	init_waitqueue_head(&port->close_wait);  in gs_port_alloc()
1174 	INIT_DELAYED_WORK(&port->push, gs_rx_push);  in gs_port_alloc()
1176 	INIT_LIST_HEAD(&port->read_pool);  in gs_port_alloc()
1177 	INIT_LIST_HEAD(&port->read_queue);  in gs_port_alloc()
1178 	INIT_LIST_HEAD(&port->write_pool);  in gs_port_alloc()
1180 	port->port_num = port_num;  in gs_port_alloc()
1181 	port->port_line_coding = *coding;  in gs_port_alloc()
1183 	ports[port_num].port = port;  in gs_port_alloc()
1189 static int gs_closed(struct gs_port *port)  in gs_closed()  argument
1193 	spin_lock_irq(&port->port_lock);  in gs_closed()
1194 	cond = port->port.count == 0;  in gs_closed()
1195 	spin_unlock_irq(&port->port_lock);  in gs_closed()
1200 static void gserial_free_port(struct gs_port *port)  in gserial_free_port()  argument
1202 	cancel_delayed_work_sync(&port->push);  in gserial_free_port()
1204 	wait_event(port->close_wait, gs_closed(port));  in gserial_free_port()
1205 	WARN_ON(port->port_usb != NULL);  in gserial_free_port()
1206 	tty_port_destroy(&port->port);  in gserial_free_port()
1207 	kfree(port);  in gserial_free_port()
1212 	struct gs_port	*port;  in gserial_free_line()  local
1215 	if (!ports[port_num].port) {  in gserial_free_line()
1219 	port = ports[port_num].port;  in gserial_free_line()
1220 	gs_console_exit(port);  in gserial_free_line()
1221 	ports[port_num].port = NULL;  in gserial_free_line()
1224 	gserial_free_port(port);  in gserial_free_line()
1232 	struct gs_port			*port;  in gserial_alloc_line_no_console()  local
1255 	port = ports[port_num].port;  in gserial_alloc_line_no_console()
1256 	tty_dev = tty_port_register_device(&port->port,  in gserial_alloc_line_no_console()
1259 		pr_err("%s: failed to register tty for port %d, err %ld\n",  in gserial_alloc_line_no_console()
1264 		ports[port_num].port = NULL;  in gserial_alloc_line_no_console()
1266 		gserial_free_port(port);  in gserial_alloc_line_no_console()
1280 		gs_console_init(ports[*line_num].port);  in gserial_alloc_line()
1289  * @port_num: which port is active
1309 	struct gs_port	*port;  in gserial_connect()  local
1316 	port = ports[port_num].port;  in gserial_connect()
1317 	if (!port) {  in gserial_connect()
1321 	if (port->port_usb) {  in gserial_connect()
1330 	gser->in->driver_data = port;  in gserial_connect()
1335 	gser->out->driver_data = port;  in gserial_connect()
1338 	spin_lock_irqsave(&port->port_lock, flags);  in gserial_connect()
1339 	gser->ioport = port;  in gserial_connect()
1340 	port->port_usb = gser;  in gserial_connect()
1345 	gser->port_line_coding = port->port_line_coding;  in gserial_connect()
1352 	if (port->port.count) {  in gserial_connect()
1353 		pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);  in gserial_connect()
1354 		gs_start_io(port);  in gserial_connect()
1362 	status = gs_console_connect(port);  in gserial_connect()
1363 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_connect()
1385 	struct gs_port	*port = gser->ioport;  in gserial_disconnect()  local
1388 	if (!port)  in gserial_disconnect()
1394 	spin_lock(&port->port_lock);  in gserial_disconnect()
1396 	gs_console_disconnect(port);  in gserial_disconnect()
1399 	port->port_line_coding = gser->port_line_coding;  in gserial_disconnect()
1401 	port->port_usb = NULL;  in gserial_disconnect()
1403 	if (port->port.count > 0) {  in gserial_disconnect()
1404 		wake_up_interruptible(&port->drain_wait);  in gserial_disconnect()
1405 		if (port->port.tty)  in gserial_disconnect()
1406 			tty_hangup(port->port.tty);  in gserial_disconnect()
1408 	port->suspended = false;  in gserial_disconnect()
1409 	spin_unlock(&port->port_lock);  in gserial_disconnect()
1417 	spin_lock_irqsave(&port->port_lock, flags);  in gserial_disconnect()
1418 	if (port->port.count == 0)  in gserial_disconnect()
1419 		kfifo_free(&port->port_write_buf);  in gserial_disconnect()
1420 	gs_free_requests(gser->out, &port->read_pool, NULL);  in gserial_disconnect()
1421 	gs_free_requests(gser->out, &port->read_queue, NULL);  in gserial_disconnect()
1422 	gs_free_requests(gser->in, &port->write_pool, NULL);  in gserial_disconnect()
1424 	port->read_allocated = port->read_started =  in gserial_disconnect()
1425 		port->write_allocated = port->write_started = 0;  in gserial_disconnect()
1427 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_disconnect()
1433 	struct gs_port	*port;  in gserial_suspend()  local
1437 	port = gser->ioport;  in gserial_suspend()
1439 	if (!port) {  in gserial_suspend()
1444 	spin_lock(&port->port_lock);  in gserial_suspend()
1446 	port->suspended = true;  in gserial_suspend()
1447 	port->start_delayed = true;  in gserial_suspend()
1448 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_suspend()
1454 	struct gs_port *port;  in gserial_resume()  local
1458 	port = gser->ioport;  in gserial_resume()
1460 	if (!port) {  in gserial_resume()
1465 	spin_lock(&port->port_lock);  in gserial_resume()
1467 	port->suspended = false;  in gserial_resume()
1468 	if (!port->start_delayed) {  in gserial_resume()
1469 		spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_resume()
1473 	pr_debug("delayed start ttyGS%d\n", port->port_num);  in gserial_resume()
1474 	gs_start_io(port);  in gserial_resume()
1477 	port->start_delayed = false;  in gserial_resume()
1478 	spin_unlock_irqrestore(&port->port_lock, flags);  in gserial_resume()