drivers/usb/gadget/function/u_serial.c

   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/interrupt.h>
  20 #include <linux/device.h>
  21 #include <linux/delay.h>
  22 #include <linux/tty.h>
  23 #include <linux/tty_flip.h>
  24 #include <linux/slab.h>
  25 #include <linux/export.h>
  26 #include <linux/module.h>
  27 #include <linux/console.h>
  28 #include <linux/kthread.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 */
  85 struct gscons_info {
  86         struct gs_port          *port;
  87         struct task_struct      *console_thread;
  88         struct kfifo            con_buf;
  89         /* protect the buf and busy flag */
  90         spinlock_t              con_lock;
  91         int                     req_busy;
  92         struct usb_request      *console_req;
  93 };
  94
  95 /*
  96  * The port structure holds info for each port, one for each minor number
  97  * (and thus for each /dev/ node).
  98  */
  99 struct gs_port {
 100         struct tty_port         port;
 101         spinlock_t              port_lock;      /* guard port_* access */
 102
 103         struct gserial          *port_usb;
 104
 105         bool                    openclose;      /* open/close in progress */
 106         u8                      port_num;
 107
 108         struct list_head        read_pool;
 109         int read_started;
 110         int read_allocated;
 111         struct list_head        read_queue;
 112         unsigned                n_read;
 113         struct tasklet_struct   push;
 114
 115         struct list_head        write_pool;
 116         int write_started;
 117         int write_allocated;
 118         struct kfifo            port_write_buf;
 119         wait_queue_head_t       drain_wait;     /* wait while writes drain */
 120         bool                    write_busy;
 121         wait_queue_head_t       close_wait;
 122
 123         /* REVISIT this state ... */
 124         struct usb_cdc_line_coding port_line_coding;    /* 8-N-1 etc */
 125 };
 126
 127 static struct portmaster {
 128         struct mutex    lock;                   /* protect open/close */
 129         struct gs_port  *port;
 130 } ports[MAX_U_SERIAL_PORTS];
 131
 132 #define GS_CLOSE_TIMEOUT                15              /* seconds */
 133
 134
 135
 136 #ifdef VERBOSE_DEBUG
 137 #ifndef pr_vdebug
 138 #define pr_vdebug(fmt, arg...) \
 139         pr_debug(fmt, ##arg)
 140 #endif /* pr_vdebug */
 141 #else
 142 #ifndef pr_vdebug
 143 #define pr_vdebug(fmt, arg...) \
 144         ({ if (0) pr_debug(fmt, ##arg); })
 145 #endif /* pr_vdebug */
 146 #endif
 147
 148 /*-------------------------------------------------------------------------*/
 149
 150 /* I/O glue between TTY (upper) and USB function (lower) driver layers */
 151
 152 /*
 153  * gs_alloc_req
 154  *
 155  * Allocate a usb_request and its buffer.  Returns a pointer to the
 156  * usb_request or NULL if there is an error.
 157  */
 158 struct usb_request *
 159 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
 160 {
 161         struct usb_request *req;
 162
 163         req = usb_ep_alloc_request(ep, kmalloc_flags);
 164
 165         if (req != NULL) {
 166                 req->length = len;
 167                 req->buf = kmalloc(len, kmalloc_flags);
 168                 if (req->buf == NULL) {
 169                         usb_ep_free_request(ep, req);
 170                         return NULL;
 171                 }
 172         }
 173
 174         return req;
 175 }
 176 EXPORT_SYMBOL_GPL(gs_alloc_req);
 177
 178 /*
 179  * gs_free_req
 180  *
 181  * Free a usb_request and its buffer.
 182  */
 183 void gs_free_req(struct usb_ep *ep, struct usb_request *req)
 184 {
 185         kfree(req->buf);
 186         usb_ep_free_request(ep, req);
 187 }
 188 EXPORT_SYMBOL_GPL(gs_free_req);
 189
 190 /*
 191  * gs_send_packet
 192  *
 193  * If there is data to send, a packet is built in the given
 194  * buffer and the size is returned.  If there is no data to
 195  * send, 0 is returned.
 196  *
 197  * Called with port_lock held.
 198  */
 199 static unsigned
 200 gs_send_packet(struct gs_port *port, char *packet, unsigned size)
 201 {
 202         unsigned len;
 203
 204         len = kfifo_len(&port->port_write_buf);
 205         if (len < size)
 206                 size = len;
 207         if (size != 0)
 208                 size = kfifo_out(&port->port_write_buf, packet, size);
 209         return size;
 210 }
 211
 212 /*
 213  * gs_start_tx
 214  *
 215  * This function finds available write requests, calls
 216  * gs_send_packet to fill these packets with data, and
 217  * continues until either there are no more write requests
 218  * available or no more data to send.  This function is
 219  * run whenever data arrives or write requests are available.
 220  *
 221  * Context: caller owns port_lock; port_usb is non-null.
 222  */
 223 static int gs_start_tx(struct gs_port *port)
 224 /*
 225 __releases(&port->port_lock)
 226 __acquires(&port->port_lock)
 227 */
 228 {
 229         struct list_head        *pool = &port->write_pool;
 230         struct usb_ep           *in;
 231         int                     status = 0;
 232         bool                    do_tty_wake = false;
 233
 234         if (!port->port_usb)
 235                 return status;
 236
 237         in = port->port_usb->in;
 238
 239         while (!port->write_busy && !list_empty(pool)) {
 240                 struct usb_request      *req;
 241                 int                     len;
 242
 243                 if (port->write_started >= QUEUE_SIZE)
 244                         break;
 245
 246                 req = list_entry(pool->next, struct usb_request, list);
 247                 len = gs_send_packet(port, req->buf, in->maxpacket);
 248                 if (len == 0) {
 249                         wake_up_interruptible(&port->drain_wait);
 250                         break;
 251                 }
 252                 do_tty_wake = true;
 253
 254                 req->length = len;
 255                 list_del(&req->list);
 256                 req->zero = kfifo_is_empty(&port->port_write_buf);
 257
 258                 pr_vdebug("ttyGS%d: tx len=%d, 0x%02x 0x%02x 0x%02x ...\n",
 259                           port->port_num, len, *((u8 *)req->buf),
 260                           *((u8 *)req->buf+1), *((u8 *)req->buf+2));
 261
 262                 /* Drop lock while we call out of driver; completions
 263                  * could be issued while we do so.  Disconnection may
 264                  * happen too; maybe immediately before we queue this!
 265                  *
 266                  * NOTE that we may keep sending data for a while after
 267                  * the TTY closed (dev->ioport->port_tty is NULL).
 268                  */
 269                 port->write_busy = true;
 270                 spin_unlock(&port->port_lock);
 271                 status = usb_ep_queue(in, req, GFP_ATOMIC);
 272                 spin_lock(&port->port_lock);
 273                 port->write_busy = false;
 274
 275                 if (status) {
 276                         pr_debug("%s: %s %s err %d\n",
 277                                         __func__, "queue", in->name, status);
 278                         list_add(&req->list, pool);
 279                         break;
 280                 }
 281
 282                 port->write_started++;
 283
 284                 /* abort immediately after disconnect */
 285                 if (!port->port_usb)
 286                         break;
 287         }
 288
 289         if (do_tty_wake && port->port.tty)
 290                 tty_wakeup(port->port.tty);
 291         return status;
 292 }
 293
 294 /*
 295  * Context: caller owns port_lock, and port_usb is set
 296  */
 297 static unsigned gs_start_rx(struct gs_port *port)
 298 /*
 299 __releases(&port->port_lock)
 300 __acquires(&port->port_lock)
 301 */
 302 {
 303         struct list_head        *pool = &port->read_pool;
 304         struct usb_ep           *out = port->port_usb->out;
 305
 306         while (!list_empty(pool)) {
 307                 struct usb_request      *req;
 308                 int                     status;
 309                 struct tty_struct       *tty;
 310
 311                 /* no more rx if closed */
 312                 tty = port->port.tty;
 313                 if (!tty)
 314                         break;
 315
 316                 if (port->read_started >= QUEUE_SIZE)
 317                         break;
 318
 319                 req = list_entry(pool->next, struct usb_request, list);
 320                 list_del(&req->list);
 321                 req->length = out->maxpacket;
 322
 323                 /* drop lock while we call out; the controller driver
 324                  * may need to call us back (e.g. for disconnect)
 325                  */
 326                 spin_unlock(&port->port_lock);
 327                 status = usb_ep_queue(out, req, GFP_ATOMIC);
 328                 spin_lock(&port->port_lock);
 329
 330                 if (status) {
 331                         pr_debug("%s: %s %s err %d\n",
 332                                         __func__, "queue", out->name, status);
 333                         list_add(&req->list, pool);
 334                         break;
 335                 }
 336                 port->read_started++;
 337
 338                 /* abort immediately after disconnect */
 339                 if (!port->port_usb)
 340                         break;
 341         }
 342         return port->read_started;
 343 }
 344
 345 /*
 346  * RX tasklet takes data out of the RX queue and hands it up to the TTY
 347  * layer until it refuses to take any more data (or is throttled back).
 348  * Then it issues reads for any further data.
 349  *
 350  * If the RX queue becomes full enough that no usb_request is queued,
 351  * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
 352  * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
 353  * can be buffered before the TTY layer's buffers (currently 64 KB).
 354  */
 355 static void gs_rx_push(unsigned long _port)
 356 {
 357         struct gs_port          *port = (void *)_port;
 358         struct tty_struct       *tty;
 359         struct list_head        *queue = &port->read_queue;
 360         bool                    disconnect = false;
 361         bool                    do_push = false;
 362
 363         /* hand any queued data to the tty */
 364         spin_lock_irq(&port->port_lock);
 365         tty = port->port.tty;
 366         while (!list_empty(queue)) {
 367                 struct usb_request      *req;
 368
 369                 req = list_first_entry(queue, struct usb_request, list);
 370
 371                 /* leave data queued if tty was rx throttled */
 372                 if (tty && tty_throttled(tty))
 373                         break;
 374
 375                 switch (req->status) {
 376                 case -ESHUTDOWN:
 377                         disconnect = true;
 378                         pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
 379                         break;
 380
 381                 default:
 382                         /* presumably a transient fault */
 383                         pr_warn("ttyGS%d: unexpected RX status %d\n",
 384                                 port->port_num, req->status);
 385                         /* FALLTHROUGH */
 386                 case 0:
 387                         /* normal completion */
 388                         break;
 389                 }
 390
 391                 /* push data to (open) tty */
 392                 if (req->actual && tty) {
 393                         char            *packet = req->buf;
 394                         unsigned        size = req->actual;
 395                         unsigned        n;
 396                         int             count;
 397
 398                         /* we may have pushed part of this packet already... */
 399                         n = port->n_read;
 400                         if (n) {
 401                                 packet += n;
 402                                 size -= n;
 403                         }
 404
 405                         count = tty_insert_flip_string(&port->port, packet,
 406                                         size);
 407                         if (count)
 408                                 do_push = true;
 409                         if (count != size) {
 410                                 /* stop pushing; TTY layer can't handle more */
 411                                 port->n_read += count;
 412                                 pr_vdebug("ttyGS%d: rx block %d/%d\n",
 413                                           port->port_num, count, req->actual);
 414                                 break;
 415                         }
 416                         port->n_read = 0;
 417                 }
 418
 419                 list_move(&req->list, &port->read_pool);
 420                 port->read_started--;
 421         }
 422
 423         /* Push from tty to ldisc; this is handled by a workqueue,
 424          * so we won't get callbacks and can hold port_lock
 425          */
 426         if (do_push)
 427                 tty_flip_buffer_push(&port->port);
 428
 429
 430         /* We want our data queue to become empty ASAP, keeping data
 431          * in the tty and ldisc (not here).  If we couldn't push any
 432          * this time around, there may be trouble unless there's an
 433          * implicit tty_unthrottle() call on its way...
 434          *
 435          * REVISIT we should probably add a timer to keep the tasklet
 436          * from starving ... but it's not clear that case ever happens.
 437          */
 438         if (!list_empty(queue) && tty) {
 439                 if (!tty_throttled(tty)) {
 440                         if (do_push)
 441                                 tasklet_schedule(&port->push);
 442                         else
 443                                 pr_warn("ttyGS%d: RX not scheduled?\n",
 444                                         port->port_num);
 445                 }
 446         }
 447
 448         /* If we're still connected, refill the USB RX queue. */
 449         if (!disconnect && port->port_usb)
 450                 gs_start_rx(port);
 451
 452         spin_unlock_irq(&port->port_lock);
 453 }
 454
 455 static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
 456 {
 457         struct gs_port  *port = ep->driver_data;
 458
 459         /* Queue all received data until the tty layer is ready for it. */
 460         spin_lock(&port->port_lock);
 461         list_add_tail(&req->list, &port->read_queue);
 462         tasklet_schedule(&port->push);
 463         spin_unlock(&port->port_lock);
 464 }
 465
 466 static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
 467 {
 468         struct gs_port  *port = ep->driver_data;
 469
 470         spin_lock(&port->port_lock);
 471         list_add(&req->list, &port->write_pool);
 472         port->write_started--;
 473
 474         switch (req->status) {
 475         default:
 476                 /* presumably a transient fault */
 477                 pr_warn("%s: unexpected %s status %d\n",
 478                         __func__, ep->name, req->status);
 479                 /* FALL THROUGH */
 480         case 0:
 481                 /* normal completion */
 482                 gs_start_tx(port);
 483                 break;
 484
 485         case -ESHUTDOWN:
 486                 /* disconnect */
 487                 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
 488                 break;
 489         }
 490
 491         spin_unlock(&port->port_lock);
 492 }
 493
 494 static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
 495                                                          int *allocated)
 496 {
 497         struct usb_request      *req;
 498
 499         while (!list_empty(head)) {
 500                 req = list_entry(head->next, struct usb_request, list);
 501                 list_del(&req->list);
 502                 gs_free_req(ep, req);
 503                 if (allocated)
 504                         (*allocated)--;
 505         }
 506 }
 507
 508 static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
 509                 void (*fn)(struct usb_ep *, struct usb_request *),
 510                 int *allocated)
 511 {
 512         int                     i;
 513         struct usb_request      *req;
 514         int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
 515
 516         /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
 517          * do quite that many this time, don't fail ... we just won't
 518          * be as speedy as we might otherwise be.
 519          */
 520         for (i = 0; i < n; i++) {
 521                 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
 522                 if (!req)
 523                         return list_empty(head) ? -ENOMEM : 0;
 524                 req->complete = fn;
 525                 list_add_tail(&req->list, head);
 526                 if (allocated)
 527                         (*allocated)++;
 528         }
 529         return 0;
 530 }
 531
 532 /**
 533  * gs_start_io - start USB I/O streams
 534  * @dev: encapsulates endpoints to use
 535  * Context: holding port_lock; port_tty and port_usb are non-null
 536  *
 537  * We only start I/O when something is connected to both sides of
 538  * this port.  If nothing is listening on the host side, we may
 539  * be pointlessly filling up our TX buffers and FIFO.
 540  */
 541 static int gs_start_io(struct gs_port *port)
 542 {
 543         struct list_head        *head = &port->read_pool;
 544         struct usb_ep           *ep = port->port_usb->out;
 545         int                     status;
 546         unsigned                started;
 547
 548         /* Allocate RX and TX I/O buffers.  We can't easily do this much
 549          * earlier (with GFP_KERNEL) because the requests are coupled to
 550          * endpoints, as are the packet sizes we'll be using.  Different
 551          * configurations may use different endpoints with a given port;
 552          * and high speed vs full speed changes packet sizes too.
 553          */
 554         status = gs_alloc_requests(ep, head, gs_read_complete,
 555                 &port->read_allocated);
 556         if (status)
 557                 return status;
 558
 559         status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
 560                         gs_write_complete, &port->write_allocated);
 561         if (status) {
 562                 gs_free_requests(ep, head, &port->read_allocated);
 563                 return status;
 564         }
 565
 566         /* queue read requests */
 567         port->n_read = 0;
 568         started = gs_start_rx(port);
 569
 570         if (started) {
 571                 gs_start_tx(port);
 572                 /* Unblock any pending writes into our circular buffer, in case
 573                  * we didn't in gs_start_tx() */
 574                 tty_wakeup(port->port.tty);
 575         } else {
 576                 gs_free_requests(ep, head, &port->read_allocated);
 577                 gs_free_requests(port->port_usb->in, &port->write_pool,
 578                         &port->write_allocated);
 579                 status = -EIO;
 580         }
 581
 582         return status;
 583 }
 584
 585 /*-------------------------------------------------------------------------*/
 586
 587 /* TTY Driver */
 588
 589 /*
 590  * gs_open sets up the link between a gs_port and its associated TTY.
 591  * That link is broken *only* by TTY close(), and all driver methods
 592  * know that.
 593  */
 594 static int gs_open(struct tty_struct *tty, struct file *file)
 595 {
 596         int             port_num = tty->index;
 597         struct gs_port  *port;
 598         int             status;
 599
 600         do {
 601                 mutex_lock(&ports[port_num].lock);
 602                 port = ports[port_num].port;
 603                 if (!port)
 604                         status = -ENODEV;
 605                 else {
 606                         spin_lock_irq(&port->port_lock);
 607
 608                         /* already open?  Great. */
 609                         if (port->port.count) {
 610                                 status = 0;
 611                                 port->port.count++;
 612
 613                         /* currently opening/closing? wait ... */
 614                         } else if (port->openclose) {
 615                                 status = -EBUSY;
 616
 617                         /* ... else we do the work */
 618                         } else {
 619                                 status = -EAGAIN;
 620                                 port->openclose = true;
 621                         }
 622                         spin_unlock_irq(&port->port_lock);
 623                 }
 624                 mutex_unlock(&ports[port_num].lock);
 625
 626                 switch (status) {
 627                 default:
 628                         /* fully handled */
 629                         return status;
 630                 case -EAGAIN:
 631                         /* must do the work */
 632                         break;
 633                 case -EBUSY:
 634                         /* wait for EAGAIN task to finish */
 635                         msleep(1);
 636                         /* REVISIT could have a waitchannel here, if
 637                          * concurrent open performance is important
 638                          */
 639                         break;
 640                 }
 641         } while (status != -EAGAIN);
 642
 643         /* Do the "real open" */
 644         spin_lock_irq(&port->port_lock);
 645
 646         /* allocate circular buffer on first open */
 647         if (!kfifo_initialized(&port->port_write_buf)) {
 648
 649                 spin_unlock_irq(&port->port_lock);
 650                 status = kfifo_alloc(&port->port_write_buf,
 651                                      WRITE_BUF_SIZE, GFP_KERNEL);
 652                 spin_lock_irq(&port->port_lock);
 653
 654                 if (status) {
 655                         pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
 656                                 port->port_num, tty, file);
 657                         port->openclose = false;
 658                         goto exit_unlock_port;
 659                 }
 660         }
 661
 662         /* REVISIT if REMOVED (ports[].port NULL), abort the open
 663          * to let rmmod work faster (but this way isn't wrong).
 664          */
 665
 666         /* REVISIT maybe wait for "carrier detect" */
 667
 668         tty->driver_data = port;
 669         port->port.tty = tty;
 670
 671         port->port.count = 1;
 672         port->openclose = false;
 673
 674         /* if connected, start the I/O stream */
 675         if (port->port_usb) {
 676                 struct gserial  *gser = port->port_usb;
 677
 678                 pr_debug("gs_open: start ttyGS%d\n", port->port_num);
 679                 gs_start_io(port);
 680
 681                 if (gser->connect)
 682                         gser->connect(gser);
 683         }
 684
 685         pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
 686
 687         status = 0;
 688
 689 exit_unlock_port:
 690         spin_unlock_irq(&port->port_lock);
 691         return status;
 692 }
 693
 694 static int gs_writes_finished(struct gs_port *p)
 695 {
 696         int cond;
 697
 698         /* return true on disconnect or empty buffer */
 699         spin_lock_irq(&p->port_lock);
 700         cond = (p->port_usb == NULL) || !kfifo_len(&p->port_write_buf);
 701         spin_unlock_irq(&p->port_lock);
 702
 703         return cond;
 704 }
 705
 706 static void gs_close(struct tty_struct *tty, struct file *file)
 707 {
 708         struct gs_port *port = tty->driver_data;
 709         struct gserial  *gser;
 710
 711         spin_lock_irq(&port->port_lock);
 712
 713         if (port->port.count != 1) {
 714                 if (port->port.count == 0)
 715                         WARN_ON(1);
 716                 else
 717                         --port->port.count;
 718                 goto exit;
 719         }
 720
 721         pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
 722
 723         /* mark port as closing but in use; we can drop port lock
 724          * and sleep if necessary
 725          */
 726         port->openclose = true;
 727         port->port.count = 0;
 728
 729         gser = port->port_usb;
 730         if (gser && gser->disconnect)
 731                 gser->disconnect(gser);
 732
 733         /* wait for circular write buffer to drain, disconnect, or at
 734          * most GS_CLOSE_TIMEOUT seconds; then discard the rest
 735          */
 736         if (kfifo_len(&port->port_write_buf) > 0 && gser) {
 737                 spin_unlock_irq(&port->port_lock);
 738                 wait_event_interruptible_timeout(port->drain_wait,
 739                                         gs_writes_finished(port),
 740                                         GS_CLOSE_TIMEOUT * HZ);
 741                 spin_lock_irq(&port->port_lock);
 742                 gser = port->port_usb;
 743         }
 744
 745         /* Iff we're disconnected, there can be no I/O in flight so it's
 746          * ok to free the circular buffer; else just scrub it.  And don't
 747          * let the push tasklet fire again until we're re-opened.
 748          */
 749         if (gser == NULL)
 750                 kfifo_free(&port->port_write_buf);
 751         else
 752                 kfifo_reset(&port->port_write_buf);
 753
 754         port->port.tty = NULL;
 755
 756         port->openclose = false;
 757
 758         pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
 759                         port->port_num, tty, file);
 760
 761         wake_up(&port->close_wait);
 762 exit:
 763         spin_unlock_irq(&port->port_lock);
 764 }
 765
 766 static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
 767 {
 768         struct gs_port  *port = tty->driver_data;
 769         unsigned long   flags;
 770
 771         pr_vdebug("gs_write: ttyGS%d (%p) writing %d bytes\n",
 772                         port->port_num, tty, count);
 773
 774         spin_lock_irqsave(&port->port_lock, flags);
 775         if (count)
 776                 count = kfifo_in(&port->port_write_buf, buf, count);
 777         /* treat count == 0 as flush_chars() */
 778         if (port->port_usb)
 779                 gs_start_tx(port);
 780         spin_unlock_irqrestore(&port->port_lock, flags);
 781
 782         return count;
 783 }
 784
 785 static int gs_put_char(struct tty_struct *tty, unsigned char ch)
 786 {
 787         struct gs_port  *port = tty->driver_data;
 788         unsigned long   flags;
 789         int             status;
 790
 791         pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
 792                 port->port_num, tty, ch, __builtin_return_address(0));
 793
 794         spin_lock_irqsave(&port->port_lock, flags);
 795         status = kfifo_put(&port->port_write_buf, ch);
 796         spin_unlock_irqrestore(&port->port_lock, flags);
 797
 798         return status;
 799 }
 800
 801 static void gs_flush_chars(struct tty_struct *tty)
 802 {
 803         struct gs_port  *port = tty->driver_data;
 804         unsigned long   flags;
 805
 806         pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
 807
 808         spin_lock_irqsave(&port->port_lock, flags);
 809         if (port->port_usb)
 810                 gs_start_tx(port);
 811         spin_unlock_irqrestore(&port->port_lock, flags);
 812 }
 813
 814 static int gs_write_room(struct tty_struct *tty)
 815 {
 816         struct gs_port  *port = tty->driver_data;
 817         unsigned long   flags;
 818         int             room = 0;
 819
 820         spin_lock_irqsave(&port->port_lock, flags);
 821         if (port->port_usb)
 822                 room = kfifo_avail(&port->port_write_buf);
 823         spin_unlock_irqrestore(&port->port_lock, flags);
 824
 825         pr_vdebug("gs_write_room: (%d,%p) room=%d\n",
 826                 port->port_num, tty, room);
 827
 828         return room;
 829 }
 830
 831 static int gs_chars_in_buffer(struct tty_struct *tty)
 832 {
 833         struct gs_port  *port = tty->driver_data;
 834         unsigned long   flags;
 835         int             chars = 0;
 836
 837         spin_lock_irqsave(&port->port_lock, flags);
 838         chars = kfifo_len(&port->port_write_buf);
 839         spin_unlock_irqrestore(&port->port_lock, flags);
 840
 841         pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
 842                 port->port_num, tty, chars);
 843
 844         return chars;
 845 }
 846
 847 /* undo side effects of setting TTY_THROTTLED */
 848 static void gs_unthrottle(struct tty_struct *tty)
 849 {
 850         struct gs_port          *port = tty->driver_data;
 851         unsigned long           flags;
 852
 853         spin_lock_irqsave(&port->port_lock, flags);
 854         if (port->port_usb) {
 855                 /* Kickstart read queue processing.  We don't do xon/xoff,
 856                  * rts/cts, or other handshaking with the host, but if the
 857                  * read queue backs up enough we'll be NAKing OUT packets.
 858                  */
 859                 tasklet_schedule(&port->push);
 860                 pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
 861         }
 862         spin_unlock_irqrestore(&port->port_lock, flags);
 863 }
 864
 865 static int gs_break_ctl(struct tty_struct *tty, int duration)
 866 {
 867         struct gs_port  *port = tty->driver_data;
 868         int             status = 0;
 869         struct gserial  *gser;
 870
 871         pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
 872                         port->port_num, duration);
 873
 874         spin_lock_irq(&port->port_lock);
 875         gser = port->port_usb;
 876         if (gser && gser->send_break)
 877                 status = gser->send_break(gser, duration);
 878         spin_unlock_irq(&port->port_lock);
 879
 880         return status;
 881 }
 882
 883 static const struct tty_operations gs_tty_ops = {
 884         .open =                 gs_open,
 885         .close =                gs_close,
 886         .write =                gs_write,
 887         .put_char =             gs_put_char,
 888         .flush_chars =          gs_flush_chars,
 889         .write_room =           gs_write_room,
 890         .chars_in_buffer =      gs_chars_in_buffer,
 891         .unthrottle =           gs_unthrottle,
 892         .break_ctl =            gs_break_ctl,
 893 };
 894
 895 /*-------------------------------------------------------------------------*/
 896
 897 static struct tty_driver *gs_tty_driver;
 898
 899 #ifdef CONFIG_U_SERIAL_CONSOLE
 900
 901 static struct gscons_info gscons_info;
 902 static struct console gserial_cons;
 903
 904 static struct usb_request *gs_request_new(struct usb_ep *ep)
 905 {
 906         struct usb_request *req = usb_ep_alloc_request(ep, GFP_ATOMIC);
 907         if (!req)
 908                 return NULL;
 909
 910         req->buf = kmalloc(ep->maxpacket, GFP_ATOMIC);
 911         if (!req->buf) {
 912                 usb_ep_free_request(ep, req);
 913                 return NULL;
 914         }
 915
 916         return req;
 917 }
 918
 919 static void gs_request_free(struct usb_request *req, struct usb_ep *ep)
 920 {
 921         if (!req)
 922                 return;
 923
 924         kfree(req->buf);
 925         usb_ep_free_request(ep, req);
 926 }
 927
 928 static void gs_complete_out(struct usb_ep *ep, struct usb_request *req)
 929 {
 930         struct gscons_info *info = &gscons_info;
 931
 932         switch (req->status) {
 933         default:
 934                 pr_warn("%s: unexpected %s status %d\n",
 935                         __func__, ep->name, req->status);
 936                 /* fall through */
 937         case 0:
 938                 /* normal completion */
 939                 spin_lock(&info->con_lock);
 940                 info->req_busy = 0;
 941                 spin_unlock(&info->con_lock);
 942
 943                 wake_up_process(info->console_thread);
 944                 break;
 945         case -ESHUTDOWN:
 946                 /* disconnect */
 947                 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
 948                 break;
 949         }
 950 }
 951
 952 static int gs_console_connect(int port_num)
 953 {
 954         struct gscons_info *info = &gscons_info;
 955         struct gs_port *port;
 956         struct usb_ep *ep;
 957
 958         if (port_num != gserial_cons.index) {
 959                 pr_err("%s: port num [%d] is not support console\n",
 960                        __func__, port_num);
 961                 return -ENXIO;
 962         }
 963
 964         port = ports[port_num].port;
 965         ep = port->port_usb->in;
 966         if (!info->console_req) {
 967                 info->console_req = gs_request_new(ep);
 968                 if (!info->console_req)
 969                         return -ENOMEM;
 970                 info->console_req->complete = gs_complete_out;
 971         }
 972
 973         info->port = port;
 974         spin_lock(&info->con_lock);
 975         info->req_busy = 0;
 976         spin_unlock(&info->con_lock);
 977         pr_vdebug("port[%d] console connect!\n", port_num);
 978         return 0;
 979 }
 980
 981 static void gs_console_disconnect(struct usb_ep *ep)
 982 {
 983         struct gscons_info *info = &gscons_info;
 984         struct usb_request *req = info->console_req;
 985
 986         gs_request_free(req, ep);
 987         info->console_req = NULL;
 988 }
 989
 990 static int gs_console_thread(void *data)
 991 {
 992         struct gscons_info *info = &gscons_info;
 993         struct gs_port *port;
 994         struct usb_request *req;
 995         struct usb_ep *ep;
 996         int xfer, ret, count, size;
 997
 998         do {
 999                 port = info->port;
1000                 set_current_state(TASK_INTERRUPTIBLE);
1001                 if (!port || !port->port_usb
1002                     || !port->port_usb->in || !info->console_req)
1003                         goto sched;
1004
1005                 req = info->console_req;
1006                 ep = port->port_usb->in;
1007
1008                 spin_lock_irq(&info->con_lock);
1009                 count = kfifo_len(&info->con_buf);
1010                 size = ep->maxpacket;
1011
1012                 if (count > 0 && !info->req_busy) {
1013                         set_current_state(TASK_RUNNING);
1014                         if (count < size)
1015                                 size = count;
1016
1017                         xfer = kfifo_out(&info->con_buf, req->buf, size);
1018                         req->length = xfer;
1019
1020                         spin_unlock(&info->con_lock);
1021                         ret = usb_ep_queue(ep, req, GFP_ATOMIC);
1022                         spin_lock(&info->con_lock);
1023                         if (ret < 0)
1024                                 info->req_busy = 0;
1025                         else
1026                                 info->req_busy = 1;
1027
1028                         spin_unlock_irq(&info->con_lock);
1029                 } else {
1030                         spin_unlock_irq(&info->con_lock);
1031 sched:
1032                         if (kthread_should_stop()) {
1033                                 set_current_state(TASK_RUNNING);
1034                                 break;
1035                         }
1036                         schedule();
1037                 }
1038         } while (1);
1039
1040         return 0;
1041 }
1042
1043 static int gs_console_setup(struct console *co, char *options)
1044 {
1045         struct gscons_info *info = &gscons_info;
1046         int status;
1047
1048         info->port = NULL;
1049         info->console_req = NULL;
1050         info->req_busy = 0;
1051         spin_lock_init(&info->con_lock);
1052
1053         status = kfifo_alloc(&info->con_buf, GS_CONSOLE_BUF_SIZE, GFP_KERNEL);
1054         if (status) {
1055                 pr_err("%s: allocate console buffer failed\n", __func__);
1056                 return status;
1057         }
1058
1059         info->console_thread = kthread_create(gs_console_thread,
1060                                               co, "gs_console");
1061         if (IS_ERR(info->console_thread)) {
1062                 pr_err("%s: cannot create console thread\n", __func__);
1063                 kfifo_free(&info->con_buf);
1064                 return PTR_ERR(info->console_thread);
1065         }
1066         wake_up_process(info->console_thread);
1067
1068         return 0;
1069 }
1070
1071 static void gs_console_write(struct console *co,
1072                              const char *buf, unsigned count)
1073 {
1074         struct gscons_info *info = &gscons_info;
1075         unsigned long flags;
1076
1077         spin_lock_irqsave(&info->con_lock, flags);
1078         kfifo_in(&info->con_buf, buf, count);
1079         spin_unlock_irqrestore(&info->con_lock, flags);
1080
1081         wake_up_process(info->console_thread);
1082 }
1083
1084 static struct tty_driver *gs_console_device(struct console *co, int *index)
1085 {
1086         struct tty_driver **p = (struct tty_driver **)co->data;
1087
1088         if (!*p)
1089                 return NULL;
1090
1091         *index = co->index;
1092         return *p;
1093 }
1094
1095 static struct console gserial_cons = {
1096         .name =         "ttyGS",
1097         .write =        gs_console_write,
1098         .device =       gs_console_device,
1099         .setup =        gs_console_setup,
1100         .flags =        CON_PRINTBUFFER,
1101         .index =        -1,
1102         .data =         &gs_tty_driver,
1103 };
1104
1105 static void gserial_console_init(void)
1106 {
1107         register_console(&gserial_cons);
1108 }
1109
1110 static void gserial_console_exit(void)
1111 {
1112         struct gscons_info *info = &gscons_info;
1113
1114         unregister_console(&gserial_cons);
1115         if (!IS_ERR_OR_NULL(info->console_thread))
1116                 kthread_stop(info->console_thread);
1117         kfifo_free(&info->con_buf);
1118 }
1119
1120 #else
1121
1122 static int gs_console_connect(int port_num)
1123 {
1124         return 0;
1125 }
1126
1127 static void gs_console_disconnect(struct usb_ep *ep)
1128 {
1129 }
1130
1131 static void gserial_console_init(void)
1132 {
1133 }
1134
1135 static void gserial_console_exit(void)
1136 {
1137 }
1138
1139 #endif
1140
1141 static int
1142 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1143 {
1144         struct gs_port  *port;
1145         int             ret = 0;
1146
1147         mutex_lock(&ports[port_num].lock);
1148         if (ports[port_num].port) {
1149                 ret = -EBUSY;
1150                 goto out;
1151         }
1152
1153         port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1154         if (port == NULL) {
1155                 ret = -ENOMEM;
1156                 goto out;
1157         }
1158
1159         tty_port_init(&port->port);
1160         spin_lock_init(&port->port_lock);
1161         init_waitqueue_head(&port->drain_wait);
1162         init_waitqueue_head(&port->close_wait);
1163
1164         tasklet_init(&port->push, gs_rx_push, (unsigned long) port);
1165
1166         INIT_LIST_HEAD(&port->read_pool);
1167         INIT_LIST_HEAD(&port->read_queue);
1168         INIT_LIST_HEAD(&port->write_pool);
1169
1170         port->port_num = port_num;
1171         port->port_line_coding = *coding;
1172
1173         ports[port_num].port = port;
1174 out:
1175         mutex_unlock(&ports[port_num].lock);
1176         return ret;
1177 }
1178
1179 static int gs_closed(struct gs_port *port)
1180 {
1181         int cond;
1182
1183         spin_lock_irq(&port->port_lock);
1184         cond = (port->port.count == 0) && !port->openclose;
1185         spin_unlock_irq(&port->port_lock);
1186         return cond;
1187 }
1188
1189 static void gserial_free_port(struct gs_port *port)
1190 {
1191         tasklet_kill(&port->push);
1192         /* wait for old opens to finish */
1193         wait_event(port->close_wait, gs_closed(port));
1194         WARN_ON(port->port_usb != NULL);
1195         tty_port_destroy(&port->port);
1196         kfree(port);
1197 }
1198
1199 void gserial_free_line(unsigned char port_num)
1200 {
1201         struct gs_port  *port;
1202
1203         mutex_lock(&ports[port_num].lock);
1204         if (WARN_ON(!ports[port_num].port)) {
1205                 mutex_unlock(&ports[port_num].lock);
1206                 return;
1207         }
1208         port = ports[port_num].port;
1209         ports[port_num].port = NULL;
1210         mutex_unlock(&ports[port_num].lock);
1211
1212         gserial_free_port(port);
1213         tty_unregister_device(gs_tty_driver, port_num);
1214         gserial_console_exit();
1215 }
1216 EXPORT_SYMBOL_GPL(gserial_free_line);
1217
1218 int gserial_alloc_line(unsigned char *line_num)
1219 {
1220         struct usb_cdc_line_coding      coding;
1221         struct device                   *tty_dev;
1222         int                             ret;
1223         int                             port_num;
1224
1225         coding.dwDTERate = cpu_to_le32(9600);
1226         coding.bCharFormat = 8;
1227         coding.bParityType = USB_CDC_NO_PARITY;
1228         coding.bDataBits = USB_CDC_1_STOP_BITS;
1229
1230         for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1231                 ret = gs_port_alloc(port_num, &coding);
1232                 if (ret == -EBUSY)
1233                         continue;
1234                 if (ret)
1235                         return ret;
1236                 break;
1237         }
1238         if (ret)
1239                 return ret;
1240
1241         /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1242
1243         tty_dev = tty_port_register_device(&ports[port_num].port->port,
1244                         gs_tty_driver, port_num, NULL);
1245         if (IS_ERR(tty_dev)) {
1246                 struct gs_port  *port;
1247                 pr_err("%s: failed to register tty for port %d, err %ld\n",
1248                                 __func__, port_num, PTR_ERR(tty_dev));
1249
1250                 ret = PTR_ERR(tty_dev);
1251                 mutex_lock(&ports[port_num].lock);
1252                 port = ports[port_num].port;
1253                 ports[port_num].port = NULL;
1254                 mutex_unlock(&ports[port_num].lock);
1255                 gserial_free_port(port);
1256                 goto err;
1257         }
1258         *line_num = port_num;
1259         gserial_console_init();
1260 err:
1261         return ret;
1262 }
1263 EXPORT_SYMBOL_GPL(gserial_alloc_line);
1264
1265 /**
1266  * gserial_connect - notify TTY I/O glue that USB link is active
1267  * @gser: the function, set up with endpoints and descriptors
1268  * @port_num: which port is active
1269  * Context: any (usually from irq)
1270  *
1271  * This is called activate endpoints and let the TTY layer know that
1272  * the connection is active ... not unlike "carrier detect".  It won't
1273  * necessarily start I/O queues; unless the TTY is held open by any
1274  * task, there would be no point.  However, the endpoints will be
1275  * activated so the USB host can perform I/O, subject to basic USB
1276  * hardware flow control.
1277  *
1278  * Caller needs to have set up the endpoints and USB function in @dev
1279  * before calling this, as well as the appropriate (speed-specific)
1280  * endpoint descriptors, and also have allocate @port_num by calling
1281  * @gserial_alloc_line().
1282  *
1283  * Returns negative errno or zero.
1284  * On success, ep->driver_data will be overwritten.
1285  */
1286 int gserial_connect(struct gserial *gser, u8 port_num)
1287 {
1288         struct gs_port  *port;
1289         unsigned long   flags;
1290         int             status;
1291
1292         if (port_num >= MAX_U_SERIAL_PORTS)
1293                 return -ENXIO;
1294
1295         port = ports[port_num].port;
1296         if (!port) {
1297                 pr_err("serial line %d not allocated.\n", port_num);
1298                 return -EINVAL;
1299         }
1300         if (port->port_usb) {
1301                 pr_err("serial line %d is in use.\n", port_num);
1302                 return -EBUSY;
1303         }
1304
1305         /* activate the endpoints */
1306         status = usb_ep_enable(gser->in);
1307         if (status < 0)
1308                 return status;
1309         gser->in->driver_data = port;
1310
1311         status = usb_ep_enable(gser->out);
1312         if (status < 0)
1313                 goto fail_out;
1314         gser->out->driver_data = port;
1315
1316         /* then tell the tty glue that I/O can work */
1317         spin_lock_irqsave(&port->port_lock, flags);
1318         gser->ioport = port;
1319         port->port_usb = gser;
1320
1321         /* REVISIT unclear how best to handle this state...
1322          * we don't really couple it with the Linux TTY.
1323          */
1324         gser->port_line_coding = port->port_line_coding;
1325
1326         /* REVISIT if waiting on "carrier detect", signal. */
1327
1328         /* if it's already open, start I/O ... and notify the serial
1329          * protocol about open/close status (connect/disconnect).
1330          */
1331         if (port->port.count) {
1332                 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1333                 gs_start_io(port);
1334                 if (gser->connect)
1335                         gser->connect(gser);
1336         } else {
1337                 if (gser->disconnect)
1338                         gser->disconnect(gser);
1339         }
1340
1341         status = gs_console_connect(port_num);
1342         spin_unlock_irqrestore(&port->port_lock, flags);
1343
1344         return status;
1345
1346 fail_out:
1347         usb_ep_disable(gser->in);
1348         return status;
1349 }
1350 EXPORT_SYMBOL_GPL(gserial_connect);
1351 /**
1352  * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1353  * @gser: the function, on which gserial_connect() was called
1354  * Context: any (usually from irq)
1355  *
1356  * This is called to deactivate endpoints and let the TTY layer know
1357  * that the connection went inactive ... not unlike "hangup".
1358  *
1359  * On return, the state is as if gserial_connect() had never been called;
1360  * there is no active USB I/O on these endpoints.
1361  */
1362 void gserial_disconnect(struct gserial *gser)
1363 {
1364         struct gs_port  *port = gser->ioport;
1365         unsigned long   flags;
1366
1367         if (!port)
1368                 return;
1369
1370         /* tell the TTY glue not to do I/O here any more */
1371         spin_lock_irqsave(&port->port_lock, flags);
1372
1373         /* REVISIT as above: how best to track this? */
1374         port->port_line_coding = gser->port_line_coding;
1375
1376         port->port_usb = NULL;
1377         gser->ioport = NULL;
1378         if (port->port.count > 0 || port->openclose) {
1379                 wake_up_interruptible(&port->drain_wait);
1380                 if (port->port.tty)
1381                         tty_hangup(port->port.tty);
1382         }
1383         spin_unlock_irqrestore(&port->port_lock, flags);
1384
1385         /* disable endpoints, aborting down any active I/O */
1386         usb_ep_disable(gser->out);
1387         usb_ep_disable(gser->in);
1388
1389         /* finally, free any unused/unusable I/O buffers */
1390         spin_lock_irqsave(&port->port_lock, flags);
1391         if (port->port.count == 0 && !port->openclose)
1392                 kfifo_free(&port->port_write_buf);
1393         gs_free_requests(gser->out, &port->read_pool, NULL);
1394         gs_free_requests(gser->out, &port->read_queue, NULL);
1395         gs_free_requests(gser->in, &port->write_pool, NULL);
1396
1397         port->read_allocated = port->read_started =
1398                 port->write_allocated = port->write_started = 0;
1399
1400         gs_console_disconnect(gser->in);
1401         spin_unlock_irqrestore(&port->port_lock, flags);
1402 }
1403 EXPORT_SYMBOL_GPL(gserial_disconnect);
1404
1405 static int userial_init(void)
1406 {
1407         unsigned                        i;
1408         int                             status;
1409
1410         gs_tty_driver = alloc_tty_driver(MAX_U_SERIAL_PORTS);
1411         if (!gs_tty_driver)
1412                 return -ENOMEM;
1413
1414         gs_tty_driver->driver_name = "g_serial";
1415         gs_tty_driver->name = "ttyGS";
1416         /* uses dynamically assigned dev_t values */
1417
1418         gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
1419         gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
1420         gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
1421         gs_tty_driver->init_termios = tty_std_termios;
1422
1423         /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1424          * MS-Windows.  Otherwise, most of these flags shouldn't affect
1425          * anything unless we were to actually hook up to a serial line.
1426          */
1427         gs_tty_driver->init_termios.c_cflag =
1428                         B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1429         gs_tty_driver->init_termios.c_ispeed = 9600;
1430         gs_tty_driver->init_termios.c_ospeed = 9600;
1431
1432         tty_set_operations(gs_tty_driver, &gs_tty_ops);
1433         for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1434                 mutex_init(&ports[i].lock);
1435
1436         /* export the driver ... */
1437         status = tty_register_driver(gs_tty_driver);
1438         if (status) {
1439                 pr_err("%s: cannot register, err %d\n",
1440                                 __func__, status);
1441                 goto fail;
1442         }
1443
1444         pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1445                         MAX_U_SERIAL_PORTS,
1446                         (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1447
1448         return status;
1449 fail:
1450         put_tty_driver(gs_tty_driver);
1451         gs_tty_driver = NULL;
1452         return status;
1453 }
1454 module_init(userial_init);
1455
1456 static void userial_cleanup(void)
1457 {
1458         tty_unregister_driver(gs_tty_driver);
1459         put_tty_driver(gs_tty_driver);
1460         gs_tty_driver = NULL;
1461 }
1462 module_exit(userial_cleanup);
1463
1464 MODULE_LICENSE("GPL");