cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
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u_serial.c (37049B)


      1// SPDX-License-Identifier: GPL-2.0+
      2/*
      3 * u_serial.c - utilities for USB gadget "serial port"/TTY support
      4 *
      5 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
      6 * Copyright (C) 2008 David Brownell
      7 * Copyright (C) 2008 by Nokia Corporation
      8 *
      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)
     13 */
     14
     15/* #define VERBOSE_DEBUG */
     16
     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>
     30
     31#include "u_serial.h"
     32
     33
     34/*
     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.
     38 *
     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.
     45 *
     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
     51 * of this component.
     52 *
     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.
     58 *
     59 *
     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
     63 *
     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
     69 *
     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
     74 */
     75
     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.
     79 */
     80#define QUEUE_SIZE		16
     81#define WRITE_BUF_SIZE		8192		/* TX only */
     82#define GS_CONSOLE_BUF_SIZE	8192
     83
     84/* console info */
     85struct gs_console {
     86	struct console		console;
     87	struct work_struct	work;
     88	spinlock_t		lock;
     89	struct usb_request	*req;
     90	struct kfifo		buf;
     91	size_t			missed;
     92};
     93
     94/*
     95 * The port structure holds info for each port, one for each minor number
     96 * (and thus for each /dev/ node).
     97 */
     98struct gs_port {
     99	struct tty_port		port;
    100	spinlock_t		port_lock;	/* guard port_* access */
    101
    102	struct gserial		*port_usb;
    103#ifdef CONFIG_U_SERIAL_CONSOLE
    104	struct gs_console	*console;
    105#endif
    106
    107	u8			port_num;
    108
    109	struct list_head	read_pool;
    110	int read_started;
    111	int read_allocated;
    112	struct list_head	read_queue;
    113	unsigned		n_read;
    114	struct delayed_work	push;
    115
    116	struct list_head	write_pool;
    117	int write_started;
    118	int write_allocated;
    119	struct kfifo		port_write_buf;
    120	wait_queue_head_t	drain_wait;	/* wait while writes drain */
    121	bool                    write_busy;
    122	wait_queue_head_t	close_wait;
    123	bool			suspended;	/* port suspended */
    124	bool			start_delayed;	/* delay start when suspended */
    125
    126	/* REVISIT this state ... */
    127	struct usb_cdc_line_coding port_line_coding;	/* 8-N-1 etc */
    128};
    129
    130static struct portmaster {
    131	struct mutex	lock;			/* protect open/close */
    132	struct gs_port	*port;
    133} ports[MAX_U_SERIAL_PORTS];
    134
    135#define GS_CLOSE_TIMEOUT		15		/* seconds */
    136
    137
    138
    139#ifdef VERBOSE_DEBUG
    140#ifndef pr_vdebug
    141#define pr_vdebug(fmt, arg...) \
    142	pr_debug(fmt, ##arg)
    143#endif /* pr_vdebug */
    144#else
    145#ifndef pr_vdebug
    146#define pr_vdebug(fmt, arg...) \
    147	({ if (0) pr_debug(fmt, ##arg); })
    148#endif /* pr_vdebug */
    149#endif
    150
    151/*-------------------------------------------------------------------------*/
    152
    153/* I/O glue between TTY (upper) and USB function (lower) driver layers */
    154
    155/*
    156 * gs_alloc_req
    157 *
    158 * Allocate a usb_request and its buffer.  Returns a pointer to the
    159 * usb_request or NULL if there is an error.
    160 */
    161struct usb_request *
    162gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
    163{
    164	struct usb_request *req;
    165
    166	req = usb_ep_alloc_request(ep, kmalloc_flags);
    167
    168	if (req != NULL) {
    169		req->length = len;
    170		req->buf = kmalloc(len, kmalloc_flags);
    171		if (req->buf == NULL) {
    172			usb_ep_free_request(ep, req);
    173			return NULL;
    174		}
    175	}
    176
    177	return req;
    178}
    179EXPORT_SYMBOL_GPL(gs_alloc_req);
    180
    181/*
    182 * gs_free_req
    183 *
    184 * Free a usb_request and its buffer.
    185 */
    186void gs_free_req(struct usb_ep *ep, struct usb_request *req)
    187{
    188	kfree(req->buf);
    189	usb_ep_free_request(ep, req);
    190}
    191EXPORT_SYMBOL_GPL(gs_free_req);
    192
    193/*
    194 * gs_send_packet
    195 *
    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.
    199 *
    200 * Called with port_lock held.
    201 */
    202static unsigned
    203gs_send_packet(struct gs_port *port, char *packet, unsigned size)
    204{
    205	unsigned len;
    206
    207	len = kfifo_len(&port->port_write_buf);
    208	if (len < size)
    209		size = len;
    210	if (size != 0)
    211		size = kfifo_out(&port->port_write_buf, packet, size);
    212	return size;
    213}
    214
    215/*
    216 * gs_start_tx
    217 *
    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.
    223 *
    224 * Context: caller owns port_lock; port_usb is non-null.
    225 */
    226static int gs_start_tx(struct gs_port *port)
    227/*
    228__releases(&port->port_lock)
    229__acquires(&port->port_lock)
    230*/
    231{
    232	struct list_head	*pool = &port->write_pool;
    233	struct usb_ep		*in;
    234	int			status = 0;
    235	bool			do_tty_wake = false;
    236
    237	if (!port->port_usb)
    238		return status;
    239
    240	in = port->port_usb->in;
    241
    242	while (!port->write_busy && !list_empty(pool)) {
    243		struct usb_request	*req;
    244		int			len;
    245
    246		if (port->write_started >= QUEUE_SIZE)
    247			break;
    248
    249		req = list_entry(pool->next, struct usb_request, list);
    250		len = gs_send_packet(port, req->buf, in->maxpacket);
    251		if (len == 0) {
    252			wake_up_interruptible(&port->drain_wait);
    253			break;
    254		}
    255		do_tty_wake = true;
    256
    257		req->length = len;
    258		list_del(&req->list);
    259		req->zero = kfifo_is_empty(&port->port_write_buf);
    260
    261		pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);
    262
    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!
    266		 *
    267		 * NOTE that we may keep sending data for a while after
    268		 * the TTY closed (dev->ioport->port_tty is NULL).
    269		 */
    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;
    275
    276		if (status) {
    277			pr_debug("%s: %s %s err %d\n",
    278					__func__, "queue", in->name, status);
    279			list_add(&req->list, pool);
    280			break;
    281		}
    282
    283		port->write_started++;
    284
    285		/* abort immediately after disconnect */
    286		if (!port->port_usb)
    287			break;
    288	}
    289
    290	if (do_tty_wake && port->port.tty)
    291		tty_wakeup(port->port.tty);
    292	return status;
    293}
    294
    295/*
    296 * Context: caller owns port_lock, and port_usb is set
    297 */
    298static unsigned gs_start_rx(struct gs_port *port)
    299/*
    300__releases(&port->port_lock)
    301__acquires(&port->port_lock)
    302*/
    303{
    304	struct list_head	*pool = &port->read_pool;
    305	struct usb_ep		*out = port->port_usb->out;
    306
    307	while (!list_empty(pool)) {
    308		struct usb_request	*req;
    309		int			status;
    310		struct tty_struct	*tty;
    311
    312		/* no more rx if closed */
    313		tty = port->port.tty;
    314		if (!tty)
    315			break;
    316
    317		if (port->read_started >= QUEUE_SIZE)
    318			break;
    319
    320		req = list_entry(pool->next, struct usb_request, list);
    321		list_del(&req->list);
    322		req->length = out->maxpacket;
    323
    324		/* drop lock while we call out; the controller driver
    325		 * may need to call us back (e.g. for disconnect)
    326		 */
    327		spin_unlock(&port->port_lock);
    328		status = usb_ep_queue(out, req, GFP_ATOMIC);
    329		spin_lock(&port->port_lock);
    330
    331		if (status) {
    332			pr_debug("%s: %s %s err %d\n",
    333					__func__, "queue", out->name, status);
    334			list_add(&req->list, pool);
    335			break;
    336		}
    337		port->read_started++;
    338
    339		/* abort immediately after disconnect */
    340		if (!port->port_usb)
    341			break;
    342	}
    343	return port->read_started;
    344}
    345
    346/*
    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.
    350 *
    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).
    355 */
    356static void gs_rx_push(struct work_struct *work)
    357{
    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;
    364
    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;
    370
    371		req = list_first_entry(queue, struct usb_request, list);
    372
    373		/* leave data queued if tty was rx throttled */
    374		if (tty && tty_throttled(tty))
    375			break;
    376
    377		switch (req->status) {
    378		case -ESHUTDOWN:
    379			disconnect = true;
    380			pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
    381			break;
    382
    383		default:
    384			/* presumably a transient fault */
    385			pr_warn("ttyGS%d: unexpected RX status %d\n",
    386				port->port_num, req->status);
    387			fallthrough;
    388		case 0:
    389			/* normal completion */
    390			break;
    391		}
    392
    393		/* push data to (open) tty */
    394		if (req->actual && tty) {
    395			char		*packet = req->buf;
    396			unsigned	size = req->actual;
    397			unsigned	n;
    398			int		count;
    399
    400			/* we may have pushed part of this packet already... */
    401			n = port->n_read;
    402			if (n) {
    403				packet += n;
    404				size -= n;
    405			}
    406
    407			count = tty_insert_flip_string(&port->port, packet,
    408					size);
    409			if (count)
    410				do_push = true;
    411			if (count != size) {
    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);
    416				break;
    417			}
    418			port->n_read = 0;
    419		}
    420
    421		list_move(&req->list, &port->read_pool);
    422		port->read_started--;
    423	}
    424
    425	/* Push from tty to ldisc; this is handled by a workqueue,
    426	 * so we won't get callbacks and can hold port_lock
    427	 */
    428	if (do_push)
    429		tty_flip_buffer_push(&port->port);
    430
    431
    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.
    435	 *
    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.
    438	 */
    439	if (!list_empty(queue) && !tty_throttled(tty))
    440		schedule_delayed_work(&port->push, 1);
    441
    442	/* If we're still connected, refill the USB RX queue. */
    443	if (!disconnect && port->port_usb)
    444		gs_start_rx(port);
    445
    446	spin_unlock_irq(&port->port_lock);
    447}
    448
    449static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
    450{
    451	struct gs_port	*port = ep->driver_data;
    452
    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);
    458}
    459
    460static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
    461{
    462	struct gs_port	*port = ep->driver_data;
    463
    464	spin_lock(&port->port_lock);
    465	list_add(&req->list, &port->write_pool);
    466	port->write_started--;
    467
    468	switch (req->status) {
    469	default:
    470		/* presumably a transient fault */
    471		pr_warn("%s: unexpected %s status %d\n",
    472			__func__, ep->name, req->status);
    473		fallthrough;
    474	case 0:
    475		/* normal completion */
    476		gs_start_tx(port);
    477		break;
    478
    479	case -ESHUTDOWN:
    480		/* disconnect */
    481		pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
    482		break;
    483	}
    484
    485	spin_unlock(&port->port_lock);
    486}
    487
    488static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
    489							 int *allocated)
    490{
    491	struct usb_request	*req;
    492
    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);
    497		if (allocated)
    498			(*allocated)--;
    499	}
    500}
    501
    502static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
    503		void (*fn)(struct usb_ep *, struct usb_request *),
    504		int *allocated)
    505{
    506	int			i;
    507	struct usb_request	*req;
    508	int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
    509
    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.
    513	 */
    514	for (i = 0; i < n; i++) {
    515		req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
    516		if (!req)
    517			return list_empty(head) ? -ENOMEM : 0;
    518		req->complete = fn;
    519		list_add_tail(&req->list, head);
    520		if (allocated)
    521			(*allocated)++;
    522	}
    523	return 0;
    524}
    525
    526/**
    527 * gs_start_io - start USB I/O streams
    528 * @port: port to use
    529 * Context: holding port_lock; port_tty and port_usb are non-null
    530 *
    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.
    534 */
    535static int gs_start_io(struct gs_port *port)
    536{
    537	struct list_head	*head = &port->read_pool;
    538	struct usb_ep		*ep = port->port_usb->out;
    539	int			status;
    540	unsigned		started;
    541
    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.
    547	 */
    548	status = gs_alloc_requests(ep, head, gs_read_complete,
    549		&port->read_allocated);
    550	if (status)
    551		return status;
    552
    553	status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
    554			gs_write_complete, &port->write_allocated);
    555	if (status) {
    556		gs_free_requests(ep, head, &port->read_allocated);
    557		return status;
    558	}
    559
    560	/* queue read requests */
    561	port->n_read = 0;
    562	started = gs_start_rx(port);
    563
    564	if (started) {
    565		gs_start_tx(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);
    569	} else {
    570		gs_free_requests(ep, head, &port->read_allocated);
    571		gs_free_requests(port->port_usb->in, &port->write_pool,
    572			&port->write_allocated);
    573		status = -EIO;
    574	}
    575
    576	return status;
    577}
    578
    579/*-------------------------------------------------------------------------*/
    580
    581/* TTY Driver */
    582
    583/*
    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
    586 * know that.
    587 */
    588static int gs_open(struct tty_struct *tty, struct file *file)
    589{
    590	int		port_num = tty->index;
    591	struct gs_port	*port;
    592	int		status = 0;
    593
    594	mutex_lock(&ports[port_num].lock);
    595	port = ports[port_num].port;
    596	if (!port) {
    597		status = -ENODEV;
    598		goto out;
    599	}
    600
    601	spin_lock_irq(&port->port_lock);
    602
    603	/* allocate circular buffer on first open */
    604	if (!kfifo_initialized(&port->port_write_buf)) {
    605
    606		spin_unlock_irq(&port->port_lock);
    607
    608		/*
    609		 * portmaster's mutex still protects from simultaneous open(),
    610		 * and close() can't happen, yet.
    611		 */
    612
    613		status = kfifo_alloc(&port->port_write_buf,
    614				     WRITE_BUF_SIZE, GFP_KERNEL);
    615		if (status) {
    616			pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
    617				 port_num, tty, file);
    618			goto out;
    619		}
    620
    621		spin_lock_irq(&port->port_lock);
    622	}
    623
    624	/* already open?  Great. */
    625	if (port->port.count++)
    626		goto exit_unlock_port;
    627
    628	tty->driver_data = port;
    629	port->port.tty = tty;
    630
    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;
    636
    637			pr_debug("gs_open: start ttyGS%d\n", port->port_num);
    638			gs_start_io(port);
    639
    640			if (gser->connect)
    641				gser->connect(gser);
    642		} else {
    643			pr_debug("delay start of ttyGS%d\n", port->port_num);
    644			port->start_delayed = true;
    645		}
    646	}
    647
    648	pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
    649
    650exit_unlock_port:
    651	spin_unlock_irq(&port->port_lock);
    652out:
    653	mutex_unlock(&ports[port_num].lock);
    654	return status;
    655}
    656
    657static int gs_close_flush_done(struct gs_port *p)
    658{
    659	int cond;
    660
    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) ||
    664		p->port.count > 1;
    665	spin_unlock_irq(&p->port_lock);
    666
    667	return cond;
    668}
    669
    670static void gs_close(struct tty_struct *tty, struct file *file)
    671{
    672	struct gs_port *port = tty->driver_data;
    673	struct gserial	*gser;
    674
    675	spin_lock_irq(&port->port_lock);
    676
    677	if (port->port.count != 1) {
    678raced_with_open:
    679		if (port->port.count == 0)
    680			WARN_ON(1);
    681		else
    682			--port->port.count;
    683		goto exit;
    684	}
    685
    686	pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
    687
    688	gser = port->port_usb;
    689	if (gser && !port->suspended && gser->disconnect)
    690		gser->disconnect(gser);
    691
    692	/* wait for circular write buffer to drain, disconnect, or at
    693	 * most GS_CLOSE_TIMEOUT seconds; then discard the rest
    694	 */
    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);
    701
    702		if (port->port.count != 1)
    703			goto raced_with_open;
    704
    705		gser = port->port_usb;
    706	}
    707
    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.
    711	 */
    712	if (gser == NULL)
    713		kfifo_free(&port->port_write_buf);
    714	else
    715		kfifo_reset(&port->port_write_buf);
    716
    717	port->start_delayed = false;
    718	port->port.count = 0;
    719	port->port.tty = NULL;
    720
    721	pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
    722			port->port_num, tty, file);
    723
    724	wake_up(&port->close_wait);
    725exit:
    726	spin_unlock_irq(&port->port_lock);
    727}
    728
    729static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
    730{
    731	struct gs_port	*port = tty->driver_data;
    732	unsigned long	flags;
    733
    734	pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
    735			port->port_num, tty, count);
    736
    737	spin_lock_irqsave(&port->port_lock, flags);
    738	if (count)
    739		count = kfifo_in(&port->port_write_buf, buf, count);
    740	/* treat count == 0 as flush_chars() */
    741	if (port->port_usb)
    742		gs_start_tx(port);
    743	spin_unlock_irqrestore(&port->port_lock, flags);
    744
    745	return count;
    746}
    747
    748static int gs_put_char(struct tty_struct *tty, unsigned char ch)
    749{
    750	struct gs_port	*port = tty->driver_data;
    751	unsigned long	flags;
    752	int		status;
    753
    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));
    756
    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);
    760
    761	return status;
    762}
    763
    764static void gs_flush_chars(struct tty_struct *tty)
    765{
    766	struct gs_port	*port = tty->driver_data;
    767	unsigned long	flags;
    768
    769	pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
    770
    771	spin_lock_irqsave(&port->port_lock, flags);
    772	if (port->port_usb)
    773		gs_start_tx(port);
    774	spin_unlock_irqrestore(&port->port_lock, flags);
    775}
    776
    777static unsigned int gs_write_room(struct tty_struct *tty)
    778{
    779	struct gs_port	*port = tty->driver_data;
    780	unsigned long	flags;
    781	unsigned int room = 0;
    782
    783	spin_lock_irqsave(&port->port_lock, flags);
    784	if (port->port_usb)
    785		room = kfifo_avail(&port->port_write_buf);
    786	spin_unlock_irqrestore(&port->port_lock, flags);
    787
    788	pr_vdebug("gs_write_room: (%d,%p) room=%u\n",
    789		port->port_num, tty, room);
    790
    791	return room;
    792}
    793
    794static unsigned int gs_chars_in_buffer(struct tty_struct *tty)
    795{
    796	struct gs_port	*port = tty->driver_data;
    797	unsigned long	flags;
    798	unsigned int	chars;
    799
    800	spin_lock_irqsave(&port->port_lock, flags);
    801	chars = kfifo_len(&port->port_write_buf);
    802	spin_unlock_irqrestore(&port->port_lock, flags);
    803
    804	pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%u\n",
    805		port->port_num, tty, chars);
    806
    807	return chars;
    808}
    809
    810/* undo side effects of setting TTY_THROTTLED */
    811static void gs_unthrottle(struct tty_struct *tty)
    812{
    813	struct gs_port		*port = tty->driver_data;
    814	unsigned long		flags;
    815
    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.
    821		 */
    822		pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
    823		schedule_delayed_work(&port->push, 0);
    824	}
    825	spin_unlock_irqrestore(&port->port_lock, flags);
    826}
    827
    828static int gs_break_ctl(struct tty_struct *tty, int duration)
    829{
    830	struct gs_port	*port = tty->driver_data;
    831	int		status = 0;
    832	struct gserial	*gser;
    833
    834	pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
    835			port->port_num, duration);
    836
    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);
    842
    843	return status;
    844}
    845
    846static const struct tty_operations gs_tty_ops = {
    847	.open =			gs_open,
    848	.close =		gs_close,
    849	.write =		gs_write,
    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,
    856};
    857
    858/*-------------------------------------------------------------------------*/
    859
    860static struct tty_driver *gs_tty_driver;
    861
    862#ifdef CONFIG_U_SERIAL_CONSOLE
    863
    864static void gs_console_complete_out(struct usb_ep *ep, struct usb_request *req)
    865{
    866	struct gs_console *cons = req->context;
    867
    868	switch (req->status) {
    869	default:
    870		pr_warn("%s: unexpected %s status %d\n",
    871			__func__, ep->name, req->status);
    872		fallthrough;
    873	case 0:
    874		/* normal completion */
    875		spin_lock(&cons->lock);
    876		req->length = 0;
    877		schedule_work(&cons->work);
    878		spin_unlock(&cons->lock);
    879		break;
    880	case -ECONNRESET:
    881	case -ESHUTDOWN:
    882		/* disconnect */
    883		pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
    884		break;
    885	}
    886}
    887
    888static void __gs_console_push(struct gs_console *cons)
    889{
    890	struct usb_request *req = cons->req;
    891	struct usb_ep *ep;
    892	size_t size;
    893
    894	if (!req)
    895		return;	/* disconnected */
    896
    897	if (req->length)
    898		return;	/* busy */
    899
    900	ep = cons->console.data;
    901	size = kfifo_out(&cons->buf, req->buf, ep->maxpacket);
    902	if (!size)
    903		return;
    904
    905	if (cons->missed && ep->maxpacket >= 64) {
    906		char buf[64];
    907		size_t len;
    908
    909		len = sprintf(buf, "\n[missed %zu bytes]\n", cons->missed);
    910		kfifo_in(&cons->buf, buf, len);
    911		cons->missed = 0;
    912	}
    913
    914	req->length = size;
    915	if (usb_ep_queue(ep, req, GFP_ATOMIC))
    916		req->length = 0;
    917}
    918
    919static void gs_console_work(struct work_struct *work)
    920{
    921	struct gs_console *cons = container_of(work, struct gs_console, work);
    922
    923	spin_lock_irq(&cons->lock);
    924
    925	__gs_console_push(cons);
    926
    927	spin_unlock_irq(&cons->lock);
    928}
    929
    930static void gs_console_write(struct console *co,
    931			     const char *buf, unsigned count)
    932{
    933	struct gs_console *cons = container_of(co, struct gs_console, console);
    934	unsigned long flags;
    935	size_t n;
    936
    937	spin_lock_irqsave(&cons->lock, flags);
    938
    939	n = kfifo_in(&cons->buf, buf, count);
    940	if (n < count)
    941		cons->missed += count - n;
    942
    943	if (cons->req && !cons->req->length)
    944		schedule_work(&cons->work);
    945
    946	spin_unlock_irqrestore(&cons->lock, flags);
    947}
    948
    949static struct tty_driver *gs_console_device(struct console *co, int *index)
    950{
    951	*index = co->index;
    952	return gs_tty_driver;
    953}
    954
    955static int gs_console_connect(struct gs_port *port)
    956{
    957	struct gs_console *cons = port->console;
    958	struct usb_request *req;
    959	struct usb_ep *ep;
    960
    961	if (!cons)
    962		return 0;
    963
    964	ep = port->port_usb->in;
    965	req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
    966	if (!req)
    967		return -ENOMEM;
    968	req->complete = gs_console_complete_out;
    969	req->context = cons;
    970	req->length = 0;
    971
    972	spin_lock(&cons->lock);
    973	cons->req = req;
    974	cons->console.data = ep;
    975	spin_unlock(&cons->lock);
    976
    977	pr_debug("ttyGS%d: console connected!\n", port->port_num);
    978
    979	schedule_work(&cons->work);
    980
    981	return 0;
    982}
    983
    984static void gs_console_disconnect(struct gs_port *port)
    985{
    986	struct gs_console *cons = port->console;
    987	struct usb_request *req;
    988	struct usb_ep *ep;
    989
    990	if (!cons)
    991		return;
    992
    993	spin_lock(&cons->lock);
    994
    995	req = cons->req;
    996	ep = cons->console.data;
    997	cons->req = NULL;
    998
    999	spin_unlock(&cons->lock);
   1000
   1001	if (!req)
   1002		return;
   1003
   1004	usb_ep_dequeue(ep, req);
   1005	gs_free_req(ep, req);
   1006}
   1007
   1008static int gs_console_init(struct gs_port *port)
   1009{
   1010	struct gs_console *cons;
   1011	int err;
   1012
   1013	if (port->console)
   1014		return 0;
   1015
   1016	cons = kzalloc(sizeof(*port->console), GFP_KERNEL);
   1017	if (!cons)
   1018		return -ENOMEM;
   1019
   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;
   1025
   1026	INIT_WORK(&cons->work, gs_console_work);
   1027	spin_lock_init(&cons->lock);
   1028
   1029	err = kfifo_alloc(&cons->buf, GS_CONSOLE_BUF_SIZE, GFP_KERNEL);
   1030	if (err) {
   1031		pr_err("ttyGS%d: allocate console buffer failed\n", port->port_num);
   1032		kfree(cons);
   1033		return err;
   1034	}
   1035
   1036	port->console = cons;
   1037	register_console(&cons->console);
   1038
   1039	spin_lock_irq(&port->port_lock);
   1040	if (port->port_usb)
   1041		gs_console_connect(port);
   1042	spin_unlock_irq(&port->port_lock);
   1043
   1044	return 0;
   1045}
   1046
   1047static void gs_console_exit(struct gs_port *port)
   1048{
   1049	struct gs_console *cons = port->console;
   1050
   1051	if (!cons)
   1052		return;
   1053
   1054	unregister_console(&cons->console);
   1055
   1056	spin_lock_irq(&port->port_lock);
   1057	if (cons->req)
   1058		gs_console_disconnect(port);
   1059	spin_unlock_irq(&port->port_lock);
   1060
   1061	cancel_work_sync(&cons->work);
   1062	kfifo_free(&cons->buf);
   1063	kfree(cons);
   1064	port->console = NULL;
   1065}
   1066
   1067ssize_t gserial_set_console(unsigned char port_num, const char *page, size_t count)
   1068{
   1069	struct gs_port *port;
   1070	bool enable;
   1071	int ret;
   1072
   1073	ret = strtobool(page, &enable);
   1074	if (ret)
   1075		return ret;
   1076
   1077	mutex_lock(&ports[port_num].lock);
   1078	port = ports[port_num].port;
   1079
   1080	if (WARN_ON(port == NULL)) {
   1081		ret = -ENXIO;
   1082		goto out;
   1083	}
   1084
   1085	if (enable)
   1086		ret = gs_console_init(port);
   1087	else
   1088		gs_console_exit(port);
   1089out:
   1090	mutex_unlock(&ports[port_num].lock);
   1091
   1092	return ret < 0 ? ret : count;
   1093}
   1094EXPORT_SYMBOL_GPL(gserial_set_console);
   1095
   1096ssize_t gserial_get_console(unsigned char port_num, char *page)
   1097{
   1098	struct gs_port *port;
   1099	ssize_t ret;
   1100
   1101	mutex_lock(&ports[port_num].lock);
   1102	port = ports[port_num].port;
   1103
   1104	if (WARN_ON(port == NULL))
   1105		ret = -ENXIO;
   1106	else
   1107		ret = sprintf(page, "%u\n", !!port->console);
   1108
   1109	mutex_unlock(&ports[port_num].lock);
   1110
   1111	return ret;
   1112}
   1113EXPORT_SYMBOL_GPL(gserial_get_console);
   1114
   1115#else
   1116
   1117static int gs_console_connect(struct gs_port *port)
   1118{
   1119	return 0;
   1120}
   1121
   1122static void gs_console_disconnect(struct gs_port *port)
   1123{
   1124}
   1125
   1126static int gs_console_init(struct gs_port *port)
   1127{
   1128	return -ENOSYS;
   1129}
   1130
   1131static void gs_console_exit(struct gs_port *port)
   1132{
   1133}
   1134
   1135#endif
   1136
   1137static int
   1138gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
   1139{
   1140	struct gs_port	*port;
   1141	int		ret = 0;
   1142
   1143	mutex_lock(&ports[port_num].lock);
   1144	if (ports[port_num].port) {
   1145		ret = -EBUSY;
   1146		goto out;
   1147	}
   1148
   1149	port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
   1150	if (port == NULL) {
   1151		ret = -ENOMEM;
   1152		goto out;
   1153	}
   1154
   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);
   1159
   1160	INIT_DELAYED_WORK(&port->push, gs_rx_push);
   1161
   1162	INIT_LIST_HEAD(&port->read_pool);
   1163	INIT_LIST_HEAD(&port->read_queue);
   1164	INIT_LIST_HEAD(&port->write_pool);
   1165
   1166	port->port_num = port_num;
   1167	port->port_line_coding = *coding;
   1168
   1169	ports[port_num].port = port;
   1170out:
   1171	mutex_unlock(&ports[port_num].lock);
   1172	return ret;
   1173}
   1174
   1175static int gs_closed(struct gs_port *port)
   1176{
   1177	int cond;
   1178
   1179	spin_lock_irq(&port->port_lock);
   1180	cond = port->port.count == 0;
   1181	spin_unlock_irq(&port->port_lock);
   1182
   1183	return cond;
   1184}
   1185
   1186static void gserial_free_port(struct gs_port *port)
   1187{
   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);
   1193	kfree(port);
   1194}
   1195
   1196void gserial_free_line(unsigned char port_num)
   1197{
   1198	struct gs_port	*port;
   1199
   1200	mutex_lock(&ports[port_num].lock);
   1201	if (!ports[port_num].port) {
   1202		mutex_unlock(&ports[port_num].lock);
   1203		return;
   1204	}
   1205	port = ports[port_num].port;
   1206	gs_console_exit(port);
   1207	ports[port_num].port = NULL;
   1208	mutex_unlock(&ports[port_num].lock);
   1209
   1210	gserial_free_port(port);
   1211	tty_unregister_device(gs_tty_driver, port_num);
   1212}
   1213EXPORT_SYMBOL_GPL(gserial_free_line);
   1214
   1215int gserial_alloc_line_no_console(unsigned char *line_num)
   1216{
   1217	struct usb_cdc_line_coding	coding;
   1218	struct gs_port			*port;
   1219	struct device			*tty_dev;
   1220	int				ret;
   1221	int				port_num;
   1222
   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;
   1227
   1228	for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
   1229		ret = gs_port_alloc(port_num, &coding);
   1230		if (ret == -EBUSY)
   1231			continue;
   1232		if (ret)
   1233			return ret;
   1234		break;
   1235	}
   1236	if (ret)
   1237		return ret;
   1238
   1239	/* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
   1240
   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));
   1247
   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);
   1253		goto err;
   1254	}
   1255	*line_num = port_num;
   1256err:
   1257	return ret;
   1258}
   1259EXPORT_SYMBOL_GPL(gserial_alloc_line_no_console);
   1260
   1261int gserial_alloc_line(unsigned char *line_num)
   1262{
   1263	int ret = gserial_alloc_line_no_console(line_num);
   1264
   1265	if (!ret && !*line_num)
   1266		gs_console_init(ports[*line_num].port);
   1267
   1268	return ret;
   1269}
   1270EXPORT_SYMBOL_GPL(gserial_alloc_line);
   1271
   1272/**
   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)
   1277 *
   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.
   1284 *
   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().
   1289 *
   1290 * Returns negative errno or zero.
   1291 * On success, ep->driver_data will be overwritten.
   1292 */
   1293int gserial_connect(struct gserial *gser, u8 port_num)
   1294{
   1295	struct gs_port	*port;
   1296	unsigned long	flags;
   1297	int		status;
   1298
   1299	if (port_num >= MAX_U_SERIAL_PORTS)
   1300		return -ENXIO;
   1301
   1302	port = ports[port_num].port;
   1303	if (!port) {
   1304		pr_err("serial line %d not allocated.\n", port_num);
   1305		return -EINVAL;
   1306	}
   1307	if (port->port_usb) {
   1308		pr_err("serial line %d is in use.\n", port_num);
   1309		return -EBUSY;
   1310	}
   1311
   1312	/* activate the endpoints */
   1313	status = usb_ep_enable(gser->in);
   1314	if (status < 0)
   1315		return status;
   1316	gser->in->driver_data = port;
   1317
   1318	status = usb_ep_enable(gser->out);
   1319	if (status < 0)
   1320		goto fail_out;
   1321	gser->out->driver_data = port;
   1322
   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;
   1327
   1328	/* REVISIT unclear how best to handle this state...
   1329	 * we don't really couple it with the Linux TTY.
   1330	 */
   1331	gser->port_line_coding = port->port_line_coding;
   1332
   1333	/* REVISIT if waiting on "carrier detect", signal. */
   1334
   1335	/* if it's already open, start I/O ... and notify the serial
   1336	 * protocol about open/close status (connect/disconnect).
   1337	 */
   1338	if (port->port.count) {
   1339		pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
   1340		gs_start_io(port);
   1341		if (gser->connect)
   1342			gser->connect(gser);
   1343	} else {
   1344		if (gser->disconnect)
   1345			gser->disconnect(gser);
   1346	}
   1347
   1348	status = gs_console_connect(port);
   1349	spin_unlock_irqrestore(&port->port_lock, flags);
   1350
   1351	return status;
   1352
   1353fail_out:
   1354	usb_ep_disable(gser->in);
   1355	return status;
   1356}
   1357EXPORT_SYMBOL_GPL(gserial_connect);
   1358/**
   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)
   1362 *
   1363 * This is called to deactivate endpoints and let the TTY layer know
   1364 * that the connection went inactive ... not unlike "hangup".
   1365 *
   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.
   1368 */
   1369void gserial_disconnect(struct gserial *gser)
   1370{
   1371	struct gs_port	*port = gser->ioport;
   1372	unsigned long	flags;
   1373
   1374	if (!port)
   1375		return;
   1376
   1377	/* tell the TTY glue not to do I/O here any more */
   1378	spin_lock_irqsave(&port->port_lock, flags);
   1379
   1380	gs_console_disconnect(port);
   1381
   1382	/* REVISIT as above: how best to track this? */
   1383	port->port_line_coding = gser->port_line_coding;
   1384
   1385	port->port_usb = NULL;
   1386	gser->ioport = NULL;
   1387	if (port->port.count > 0) {
   1388		wake_up_interruptible(&port->drain_wait);
   1389		if (port->port.tty)
   1390			tty_hangup(port->port.tty);
   1391	}
   1392	port->suspended = false;
   1393	spin_unlock_irqrestore(&port->port_lock, flags);
   1394
   1395	/* disable endpoints, aborting down any active I/O */
   1396	usb_ep_disable(gser->out);
   1397	usb_ep_disable(gser->in);
   1398
   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);
   1406
   1407	port->read_allocated = port->read_started =
   1408		port->write_allocated = port->write_started = 0;
   1409
   1410	spin_unlock_irqrestore(&port->port_lock, flags);
   1411}
   1412EXPORT_SYMBOL_GPL(gserial_disconnect);
   1413
   1414void gserial_suspend(struct gserial *gser)
   1415{
   1416	struct gs_port	*port = gser->ioport;
   1417	unsigned long	flags;
   1418
   1419	spin_lock_irqsave(&port->port_lock, flags);
   1420	port->suspended = true;
   1421	spin_unlock_irqrestore(&port->port_lock, flags);
   1422}
   1423EXPORT_SYMBOL_GPL(gserial_suspend);
   1424
   1425void gserial_resume(struct gserial *gser)
   1426{
   1427	struct gs_port *port = gser->ioport;
   1428	unsigned long	flags;
   1429
   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);
   1434		return;
   1435	}
   1436
   1437	pr_debug("delayed start ttyGS%d\n", port->port_num);
   1438	gs_start_io(port);
   1439	if (gser->connect)
   1440		gser->connect(gser);
   1441	port->start_delayed = false;
   1442	spin_unlock_irqrestore(&port->port_lock, flags);
   1443}
   1444EXPORT_SYMBOL_GPL(gserial_resume);
   1445
   1446static int userial_init(void)
   1447{
   1448	struct tty_driver *driver;
   1449	unsigned			i;
   1450	int				status;
   1451
   1452	driver = tty_alloc_driver(MAX_U_SERIAL_PORTS, TTY_DRIVER_REAL_RAW |
   1453			TTY_DRIVER_DYNAMIC_DEV);
   1454	if (IS_ERR(driver))
   1455		return PTR_ERR(driver);
   1456
   1457	driver->driver_name = "g_serial";
   1458	driver->name = "ttyGS";
   1459	/* uses dynamically assigned dev_t values */
   1460
   1461	driver->type = TTY_DRIVER_TYPE_SERIAL;
   1462	driver->subtype = SERIAL_TYPE_NORMAL;
   1463	driver->init_termios = tty_std_termios;
   1464
   1465	/* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
   1466	 * MS-Windows.  Otherwise, most of these flags shouldn't affect
   1467	 * anything unless we were to actually hook up to a serial line.
   1468	 */
   1469	driver->init_termios.c_cflag =
   1470			B9600 | CS8 | CREAD | HUPCL | CLOCAL;
   1471	driver->init_termios.c_ispeed = 9600;
   1472	driver->init_termios.c_ospeed = 9600;
   1473
   1474	tty_set_operations(driver, &gs_tty_ops);
   1475	for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
   1476		mutex_init(&ports[i].lock);
   1477
   1478	/* export the driver ... */
   1479	status = tty_register_driver(driver);
   1480	if (status) {
   1481		pr_err("%s: cannot register, err %d\n",
   1482				__func__, status);
   1483		goto fail;
   1484	}
   1485
   1486	gs_tty_driver = driver;
   1487
   1488	pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
   1489			MAX_U_SERIAL_PORTS,
   1490			(MAX_U_SERIAL_PORTS == 1) ? "" : "s");
   1491
   1492	return status;
   1493fail:
   1494	tty_driver_kref_put(driver);
   1495	return status;
   1496}
   1497module_init(userial_init);
   1498
   1499static void userial_cleanup(void)
   1500{
   1501	tty_unregister_driver(gs_tty_driver);
   1502	tty_driver_kref_put(gs_tty_driver);
   1503	gs_tty_driver = NULL;
   1504}
   1505module_exit(userial_cleanup);
   1506
   1507MODULE_LICENSE("GPL");