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/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/kstrtox.h>
  28 #include <linux/kthread.h>
  29 #include <linux/workqueue.h>
  30 #include <linux/kfifo.h>
  31
  32 #include "u_serial.h"
  33
  34
  35 /*
  36  * This component encapsulates the TTY layer glue needed to provide basic
  37  * "serial port" functionality through the USB gadget stack.  Each such
  38  * port is exposed through a /dev/ttyGS* node.
  39  *
  40  * After this module has been loaded, the individual TTY port can be requested
  41  * (gserial_alloc_line()) and it will stay available until they are removed
  42  * (gserial_free_line()). Each one may be connected to a USB function
  43  * (gserial_connect), or disconnected (with gserial_disconnect) when the USB
  44  * host issues a config change event. Data can only flow when the port is
  45  * connected to the host.
  46  *
  47  * A given TTY port can be made available in multiple configurations.
  48  * For example, each one might expose a ttyGS0 node which provides a
  49  * login application.  In one case that might use CDC ACM interface 0,
  50  * while another configuration might use interface 3 for that.  The
  51  * work to handle that (including descriptor management) is not part
  52  * of this component.
  53  *
  54  * Configurations may expose more than one TTY port.  For example, if
  55  * ttyGS0 provides login service, then ttyGS1 might provide dialer access
  56  * for a telephone or fax link.  And ttyGS2 might be something that just
  57  * needs a simple byte stream interface for some messaging protocol that
  58  * is managed in userspace ... OBEX, PTP, and MTP have been mentioned.
  59  *
  60  *
  61  * gserial is the lifecycle interface, used by USB functions
  62  * gs_port is the I/O nexus, used by the tty driver
  63  * tty_struct links to the tty/filesystem framework
  64  *
  65  * gserial <---> gs_port ... links will be null when the USB link is
  66  * inactive; managed by gserial_{connect,disconnect}().  each gserial
  67  * instance can wrap its own USB control protocol.
  68  *      gserial->ioport == usb_ep->driver_data ... gs_port
  69  *      gs_port->port_usb ... gserial
  70  *
  71  * gs_port <---> tty_struct ... links will be null when the TTY file
  72  * isn't opened; managed by gs_open()/gs_close()
  73  *      gserial->port_tty ... tty_struct
  74  *      tty_struct->driver_data ... gserial
  75  */
  76
  77 /* RX and TX queues can buffer QUEUE_SIZE packets before they hit the
  78  * next layer of buffering.  For TX that's a circular buffer; for RX
  79  * consider it a NOP.  A third layer is provided by the TTY code.
  80  */
  81 #define QUEUE_SIZE              16
  82 #define WRITE_BUF_SIZE          8192            /* TX only */
  83 #define GS_CONSOLE_BUF_SIZE     8192
  84
  85 /* Prevents race conditions while accessing gser->ioport */
  86 static DEFINE_SPINLOCK(serial_port_lock);
  87
  88 /* console info */
  89 struct gs_console {
  90         struct console          console;
  91         struct work_struct      work;
  92         spinlock_t              lock;
  93         struct usb_request      *req;
  94         struct kfifo            buf;
  95         size_t                  missed;
  96 };
  97
  98 /*
  99  * The port structure holds info for each port, one for each minor number
 100  * (and thus for each /dev/ node).
 101  */
 102 struct gs_port {
 103         struct tty_port         port;
 104         spinlock_t              port_lock;      /* guard port_* access */
 105
 106         struct gserial          *port_usb;
 107 #ifdef CONFIG_U_SERIAL_CONSOLE
 108         struct gs_console       *console;
 109 #endif
 110
 111         u8                      port_num;
 112
 113         struct list_head        read_pool;
 114         int read_started;
 115         int read_allocated;
 116         struct list_head        read_queue;
 117         unsigned                n_read;
 118         struct delayed_work     push;
 119
 120         struct list_head        write_pool;
 121         int write_started;
 122         int write_allocated;
 123         struct kfifo            port_write_buf;
 124         wait_queue_head_t       drain_wait;     /* wait while writes drain */
 125         bool                    write_busy;
 126         wait_queue_head_t       close_wait;
 127         bool                    suspended;      /* port suspended */
 128         bool                    start_delayed;  /* delay start when suspended */
 129
 130         /* REVISIT this state ... */
 131         struct usb_cdc_line_coding port_line_coding;    /* 8-N-1 etc */
 132 };
 133
 134 static struct portmaster {
 135         struct mutex    lock;                   /* protect open/close */
 136         struct gs_port  *port;
 137 } ports[MAX_U_SERIAL_PORTS];
 138
 139 #define GS_CLOSE_TIMEOUT                15              /* seconds */
 140
 141
 142
 143 #ifdef VERBOSE_DEBUG
 144 #ifndef pr_vdebug
 145 #define pr_vdebug(fmt, arg...) \
 146         pr_debug(fmt, ##arg)
 147 #endif /* pr_vdebug */
 148 #else
 149 #ifndef pr_vdebug
 150 #define pr_vdebug(fmt, arg...) \
 151         ({ if (0) pr_debug(fmt, ##arg); })
 152 #endif /* pr_vdebug */
 153 #endif
 154
 155 /*-------------------------------------------------------------------------*/
 156
 157 /* I/O glue between TTY (upper) and USB function (lower) driver layers */
 158
 159 /*
 160  * gs_alloc_req
 161  *
 162  * Allocate a usb_request and its buffer.  Returns a pointer to the
 163  * usb_request or NULL if there is an error.
 164  */
 165 struct usb_request *
 166 gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t kmalloc_flags)
 167 {
 168         struct usb_request *req;
 169
 170         req = usb_ep_alloc_request(ep, kmalloc_flags);
 171
 172         if (req != NULL) {
 173                 req->length = len;
 174                 req->buf = kmalloc(len, kmalloc_flags);
 175                 if (req->buf == NULL) {
 176                         usb_ep_free_request(ep, req);
 177                         return NULL;
 178                 }
 179         }
 180
 181         return req;
 182 }
 183 EXPORT_SYMBOL_GPL(gs_alloc_req);
 184
 185 /*
 186  * gs_free_req
 187  *
 188  * Free a usb_request and its buffer.
 189  */
 190 void gs_free_req(struct usb_ep *ep, struct usb_request *req)
 191 {
 192         kfree(req->buf);
 193         usb_ep_free_request(ep, req);
 194 }
 195 EXPORT_SYMBOL_GPL(gs_free_req);
 196
 197 /*
 198  * gs_send_packet
 199  *
 200  * If there is data to send, a packet is built in the given
 201  * buffer and the size is returned.  If there is no data to
 202  * send, 0 is returned.
 203  *
 204  * Called with port_lock held.
 205  */
 206 static unsigned
 207 gs_send_packet(struct gs_port *port, char *packet, unsigned size)
 208 {
 209         unsigned len;
 210
 211         len = kfifo_len(&port->port_write_buf);
 212         if (len < size)
 213                 size = len;
 214         if (size != 0)
 215                 size = kfifo_out(&port->port_write_buf, packet, size);
 216         return size;
 217 }
 218
 219 /*
 220  * gs_start_tx
 221  *
 222  * This function finds available write requests, calls
 223  * gs_send_packet to fill these packets with data, and
 224  * continues until either there are no more write requests
 225  * available or no more data to send.  This function is
 226  * run whenever data arrives or write requests are available.
 227  *
 228  * Context: caller owns port_lock; port_usb is non-null.
 229  */
 230 static int gs_start_tx(struct gs_port *port)
 231 /*
 232 __releases(&port->port_lock)
 233 __acquires(&port->port_lock)
 234 */
 235 {
 236         struct list_head        *pool = &port->write_pool;
 237         struct usb_ep           *in;
 238         int                     status = 0;
 239         bool                    do_tty_wake = false;
 240
 241         if (!port->port_usb)
 242                 return status;
 243
 244         in = port->port_usb->in;
 245
 246         while (!port->write_busy && !list_empty(pool)) {
 247                 struct usb_request      *req;
 248                 int                     len;
 249
 250                 if (port->write_started >= QUEUE_SIZE)
 251                         break;
 252
 253                 req = list_entry(pool->next, struct usb_request, list);
 254                 len = gs_send_packet(port, req->buf, in->maxpacket);
 255                 if (len == 0) {
 256                         wake_up_interruptible(&port->drain_wait);
 257                         break;
 258                 }
 259                 do_tty_wake = true;
 260
 261                 req->length = len;
 262                 list_del(&req->list);
 263                 req->zero = kfifo_is_empty(&port->port_write_buf);
 264
 265                 pr_vdebug("ttyGS%d: tx len=%d, %3ph ...\n", port->port_num, len, req->buf);
 266
 267                 /* Drop lock while we call out of driver; completions
 268                  * could be issued while we do so.  Disconnection may
 269                  * happen too; maybe immediately before we queue this!
 270                  *
 271                  * NOTE that we may keep sending data for a while after
 272                  * the TTY closed (dev->ioport->port_tty is NULL).
 273                  */
 274                 port->write_busy = true;
 275                 spin_unlock(&port->port_lock);
 276                 status = usb_ep_queue(in, req, GFP_ATOMIC);
 277                 spin_lock(&port->port_lock);
 278                 port->write_busy = false;
 279
 280                 if (status) {
 281                         pr_debug("%s: %s %s err %d\n",
 282                                         __func__, "queue", in->name, status);
 283                         list_add(&req->list, pool);
 284                         break;
 285                 }
 286
 287                 port->write_started++;
 288
 289                 /* abort immediately after disconnect */
 290                 if (!port->port_usb)
 291                         break;
 292         }
 293
 294         if (do_tty_wake && port->port.tty)
 295                 tty_wakeup(port->port.tty);
 296         return status;
 297 }
 298
 299 /*
 300  * Context: caller owns port_lock, and port_usb is set
 301  */
 302 static unsigned gs_start_rx(struct gs_port *port)
 303 /*
 304 __releases(&port->port_lock)
 305 __acquires(&port->port_lock)
 306 */
 307 {
 308         struct list_head        *pool = &port->read_pool;
 309         struct usb_ep           *out = port->port_usb->out;
 310
 311         while (!list_empty(pool)) {
 312                 struct usb_request      *req;
 313                 int                     status;
 314                 struct tty_struct       *tty;
 315
 316                 /* no more rx if closed */
 317                 tty = port->port.tty;
 318                 if (!tty)
 319                         break;
 320
 321                 if (port->read_started >= QUEUE_SIZE)
 322                         break;
 323
 324                 req = list_entry(pool->next, struct usb_request, list);
 325                 list_del(&req->list);
 326                 req->length = out->maxpacket;
 327
 328                 /* drop lock while we call out; the controller driver
 329                  * may need to call us back (e.g. for disconnect)
 330                  */
 331                 spin_unlock(&port->port_lock);
 332                 status = usb_ep_queue(out, req, GFP_ATOMIC);
 333                 spin_lock(&port->port_lock);
 334
 335                 if (status) {
 336                         pr_debug("%s: %s %s err %d\n",
 337                                         __func__, "queue", out->name, status);
 338                         list_add(&req->list, pool);
 339                         break;
 340                 }
 341                 port->read_started++;
 342
 343                 /* abort immediately after disconnect */
 344                 if (!port->port_usb)
 345                         break;
 346         }
 347         return port->read_started;
 348 }
 349
 350 /*
 351  * RX work takes data out of the RX queue and hands it up to the TTY
 352  * layer until it refuses to take any more data (or is throttled back).
 353  * Then it issues reads for any further data.
 354  *
 355  * If the RX queue becomes full enough that no usb_request is queued,
 356  * the OUT endpoint may begin NAKing as soon as its FIFO fills up.
 357  * So QUEUE_SIZE packets plus however many the FIFO holds (usually two)
 358  * can be buffered before the TTY layer's buffers (currently 64 KB).
 359  */
 360 static void gs_rx_push(struct work_struct *work)
 361 {
 362         struct delayed_work     *w = to_delayed_work(work);
 363         struct gs_port          *port = container_of(w, struct gs_port, push);
 364         struct tty_struct       *tty;
 365         struct list_head        *queue = &port->read_queue;
 366         bool                    disconnect = false;
 367         bool                    do_push = false;
 368
 369         /* hand any queued data to the tty */
 370         spin_lock_irq(&port->port_lock);
 371         tty = port->port.tty;
 372         while (!list_empty(queue)) {
 373                 struct usb_request      *req;
 374
 375                 req = list_first_entry(queue, struct usb_request, list);
 376
 377                 /* leave data queued if tty was rx throttled */
 378                 if (tty && tty_throttled(tty))
 379                         break;
 380
 381                 switch (req->status) {
 382                 case -ESHUTDOWN:
 383                         disconnect = true;
 384                         pr_vdebug("ttyGS%d: shutdown\n", port->port_num);
 385                         break;
 386
 387                 default:
 388                         /* presumably a transient fault */
 389                         pr_warn("ttyGS%d: unexpected RX status %d\n",
 390                                 port->port_num, req->status);
 391                         fallthrough;
 392                 case 0:
 393                         /* normal completion */
 394                         break;
 395                 }
 396
 397                 /* push data to (open) tty */
 398                 if (req->actual && tty) {
 399                         char            *packet = req->buf;
 400                         unsigned        size = req->actual;
 401                         unsigned        n;
 402                         int             count;
 403
 404                         /* we may have pushed part of this packet already... */
 405                         n = port->n_read;
 406                         if (n) {
 407                                 packet += n;
 408                                 size -= n;
 409                         }
 410
 411                         count = tty_insert_flip_string(&port->port, packet,
 412                                         size);
 413                         if (count)
 414                                 do_push = true;
 415                         if (count != size) {
 416                                 /* stop pushing; TTY layer can't handle more */
 417                                 port->n_read += count;
 418                                 pr_vdebug("ttyGS%d: rx block %d/%d\n",
 419                                           port->port_num, count, req->actual);
 420                                 break;
 421                         }
 422                         port->n_read = 0;
 423                 }
 424
 425                 list_move(&req->list, &port->read_pool);
 426                 port->read_started--;
 427         }
 428
 429         /* Push from tty to ldisc; this is handled by a workqueue,
 430          * so we won't get callbacks and can hold port_lock
 431          */
 432         if (do_push)
 433                 tty_flip_buffer_push(&port->port);
 434
 435
 436         /* We want our data queue to become empty ASAP, keeping data
 437          * in the tty and ldisc (not here).  If we couldn't push any
 438          * this time around, RX may be starved, so wait until next jiffy.
 439          *
 440          * We may leave non-empty queue only when there is a tty, and
 441          * either it is throttled or there is no more room in flip buffer.
 442          */
 443         if (!list_empty(queue) && !tty_throttled(tty))
 444                 schedule_delayed_work(&port->push, 1);
 445
 446         /* If we're still connected, refill the USB RX queue. */
 447         if (!disconnect && port->port_usb)
 448                 gs_start_rx(port);
 449
 450         spin_unlock_irq(&port->port_lock);
 451 }
 452
 453 static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
 454 {
 455         struct gs_port  *port = ep->driver_data;
 456
 457         /* Queue all received data until the tty layer is ready for it. */
 458         spin_lock(&port->port_lock);
 459         list_add_tail(&req->list, &port->read_queue);
 460         schedule_delayed_work(&port->push, 0);
 461         spin_unlock(&port->port_lock);
 462 }
 463
 464 static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
 465 {
 466         struct gs_port  *port = ep->driver_data;
 467
 468         spin_lock(&port->port_lock);
 469         list_add(&req->list, &port->write_pool);
 470         port->write_started--;
 471
 472         switch (req->status) {
 473         default:
 474                 /* presumably a transient fault */
 475                 pr_warn("%s: unexpected %s status %d\n",
 476                         __func__, ep->name, req->status);
 477                 fallthrough;
 478         case 0:
 479                 /* normal completion */
 480                 gs_start_tx(port);
 481                 break;
 482
 483         case -ESHUTDOWN:
 484                 /* disconnect */
 485                 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
 486                 break;
 487         }
 488
 489         spin_unlock(&port->port_lock);
 490 }
 491
 492 static void gs_free_requests(struct usb_ep *ep, struct list_head *head,
 493                                                          int *allocated)
 494 {
 495         struct usb_request      *req;
 496
 497         while (!list_empty(head)) {
 498                 req = list_entry(head->next, struct usb_request, list);
 499                 list_del(&req->list);
 500                 gs_free_req(ep, req);
 501                 if (allocated)
 502                         (*allocated)--;
 503         }
 504 }
 505
 506 static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
 507                 void (*fn)(struct usb_ep *, struct usb_request *),
 508                 int *allocated)
 509 {
 510         int                     i;
 511         struct usb_request      *req;
 512         int n = allocated ? QUEUE_SIZE - *allocated : QUEUE_SIZE;
 513
 514         /* Pre-allocate up to QUEUE_SIZE transfers, but if we can't
 515          * do quite that many this time, don't fail ... we just won't
 516          * be as speedy as we might otherwise be.
 517          */
 518         for (i = 0; i < n; i++) {
 519                 req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
 520                 if (!req)
 521                         return list_empty(head) ? -ENOMEM : 0;
 522                 req->complete = fn;
 523                 list_add_tail(&req->list, head);
 524                 if (allocated)
 525                         (*allocated)++;
 526         }
 527         return 0;
 528 }
 529
 530 /**
 531  * gs_start_io - start USB I/O streams
 532  * @port: port to use
 533  * Context: holding port_lock; port_tty and port_usb are non-null
 534  *
 535  * We only start I/O when something is connected to both sides of
 536  * this port.  If nothing is listening on the host side, we may
 537  * be pointlessly filling up our TX buffers and FIFO.
 538  */
 539 static int gs_start_io(struct gs_port *port)
 540 {
 541         struct list_head        *head = &port->read_pool;
 542         struct usb_ep           *ep;
 543         int                     status;
 544         unsigned                started;
 545
 546         if (!port->port_usb || !port->port.tty)
 547                 return -EIO;
 548
 549         /* Allocate RX and TX I/O buffers.  We can't easily do this much
 550          * earlier (with GFP_KERNEL) because the requests are coupled to
 551          * endpoints, as are the packet sizes we'll be using.  Different
 552          * configurations may use different endpoints with a given port;
 553          * and high speed vs full speed changes packet sizes too.
 554          */
 555         ep = port->port_usb->out;
 556         status = gs_alloc_requests(ep, head, gs_read_complete,
 557                 &port->read_allocated);
 558         if (status)
 559                 return status;
 560
 561         status = gs_alloc_requests(port->port_usb->in, &port->write_pool,
 562                         gs_write_complete, &port->write_allocated);
 563         if (status) {
 564                 gs_free_requests(ep, head, &port->read_allocated);
 565                 return status;
 566         }
 567
 568         /* queue read requests */
 569         port->n_read = 0;
 570         started = gs_start_rx(port);
 571
 572         if (started) {
 573                 gs_start_tx(port);
 574                 /* Unblock any pending writes into our circular buffer, in case
 575                  * we didn't in gs_start_tx() */
 576                 tty_wakeup(port->port.tty);
 577         } else {
 578                 gs_free_requests(ep, head, &port->read_allocated);
 579                 gs_free_requests(port->port_usb->in, &port->write_pool,
 580                         &port->write_allocated);
 581                 status = -EIO;
 582         }
 583
 584         return status;
 585 }
 586
 587 /*-------------------------------------------------------------------------*/
 588
 589 /* TTY Driver */
 590
 591 /*
 592  * gs_open sets up the link between a gs_port and its associated TTY.
 593  * That link is broken *only* by TTY close(), and all driver methods
 594  * know that.
 595  */
 596 static int gs_open(struct tty_struct *tty, struct file *file)
 597 {
 598         int             port_num = tty->index;
 599         struct gs_port  *port;
 600         int             status = 0;
 601
 602         mutex_lock(&ports[port_num].lock);
 603         port = ports[port_num].port;
 604         if (!port) {
 605                 status = -ENODEV;
 606                 goto out;
 607         }
 608
 609         spin_lock_irq(&port->port_lock);
 610
 611         /* allocate circular buffer on first open */
 612         if (!kfifo_initialized(&port->port_write_buf)) {
 613
 614                 spin_unlock_irq(&port->port_lock);
 615
 616                 /*
 617                  * portmaster's mutex still protects from simultaneous open(),
 618                  * and close() can't happen, yet.
 619                  */
 620
 621                 status = kfifo_alloc(&port->port_write_buf,
 622                                      WRITE_BUF_SIZE, GFP_KERNEL);
 623                 if (status) {
 624                         pr_debug("gs_open: ttyGS%d (%p,%p) no buffer\n",
 625                                  port_num, tty, file);
 626                         goto out;
 627                 }
 628
 629                 spin_lock_irq(&port->port_lock);
 630         }
 631
 632         /* already open?  Great. */
 633         if (port->port.count++)
 634                 goto exit_unlock_port;
 635
 636         tty->driver_data = port;
 637         port->port.tty = tty;
 638
 639         /* if connected, start the I/O stream */
 640         if (port->port_usb) {
 641                 /* if port is suspended, wait resume to start I/0 stream */
 642                 if (!port->suspended) {
 643                         struct gserial  *gser = port->port_usb;
 644
 645                         pr_debug("gs_open: start ttyGS%d\n", port->port_num);
 646                         gs_start_io(port);
 647
 648                         if (gser->connect)
 649                                 gser->connect(gser);
 650                 } else {
 651                         pr_debug("delay start of ttyGS%d\n", port->port_num);
 652                         port->start_delayed = true;
 653                 }
 654         }
 655
 656         pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
 657
 658 exit_unlock_port:
 659         spin_unlock_irq(&port->port_lock);
 660 out:
 661         mutex_unlock(&ports[port_num].lock);
 662         return status;
 663 }
 664
 665 static int gs_close_flush_done(struct gs_port *p)
 666 {
 667         int cond;
 668
 669         /* return true on disconnect or empty buffer or if raced with open() */
 670         spin_lock_irq(&p->port_lock);
 671         cond = p->port_usb == NULL || !kfifo_len(&p->port_write_buf) ||
 672                 p->port.count > 1;
 673         spin_unlock_irq(&p->port_lock);
 674
 675         return cond;
 676 }
 677
 678 static void gs_close(struct tty_struct *tty, struct file *file)
 679 {
 680         struct gs_port *port = tty->driver_data;
 681         struct gserial  *gser;
 682
 683         spin_lock_irq(&port->port_lock);
 684
 685         if (port->port.count != 1) {
 686 raced_with_open:
 687                 if (port->port.count == 0)
 688                         WARN_ON(1);
 689                 else
 690                         --port->port.count;
 691                 goto exit;
 692         }
 693
 694         pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);
 695
 696         gser = port->port_usb;
 697         if (gser && !port->suspended && gser->disconnect)
 698                 gser->disconnect(gser);
 699
 700         /* wait for circular write buffer to drain, disconnect, or at
 701          * most GS_CLOSE_TIMEOUT seconds; then discard the rest
 702          */
 703         if (kfifo_len(&port->port_write_buf) > 0 && gser) {
 704                 spin_unlock_irq(&port->port_lock);
 705                 wait_event_interruptible_timeout(port->drain_wait,
 706                                         gs_close_flush_done(port),
 707                                         GS_CLOSE_TIMEOUT * HZ);
 708                 spin_lock_irq(&port->port_lock);
 709
 710                 if (port->port.count != 1)
 711                         goto raced_with_open;
 712
 713                 gser = port->port_usb;
 714         }
 715
 716         /* Iff we're disconnected, there can be no I/O in flight so it's
 717          * ok to free the circular buffer; else just scrub it.  And don't
 718          * let the push async work fire again until we're re-opened.
 719          */
 720         if (gser == NULL)
 721                 kfifo_free(&port->port_write_buf);
 722         else
 723                 kfifo_reset(&port->port_write_buf);
 724
 725         port->start_delayed = false;
 726         port->port.count = 0;
 727         port->port.tty = NULL;
 728
 729         pr_debug("gs_close: ttyGS%d (%p,%p) done!\n",
 730                         port->port_num, tty, file);
 731
 732         wake_up(&port->close_wait);
 733 exit:
 734         spin_unlock_irq(&port->port_lock);
 735 }
 736
 737 static ssize_t gs_write(struct tty_struct *tty, const u8 *buf, size_t count)
 738 {
 739         struct gs_port  *port = tty->driver_data;
 740         unsigned long   flags;
 741
 742         pr_vdebug("gs_write: ttyGS%d (%p) writing %zu bytes\n",
 743                         port->port_num, tty, count);
 744
 745         spin_lock_irqsave(&port->port_lock, flags);
 746         if (count)
 747                 count = kfifo_in(&port->port_write_buf, buf, count);
 748         /* treat count == 0 as flush_chars() */
 749         if (port->port_usb)
 750                 gs_start_tx(port);
 751         spin_unlock_irqrestore(&port->port_lock, flags);
 752
 753         return count;
 754 }
 755
 756 static int gs_put_char(struct tty_struct *tty, u8 ch)
 757 {
 758         struct gs_port  *port = tty->driver_data;
 759         unsigned long   flags;
 760         int             status;
 761
 762         pr_vdebug("gs_put_char: (%d,%p) char=0x%x, called from %ps\n",
 763                 port->port_num, tty, ch, __builtin_return_address(0));
 764
 765         spin_lock_irqsave(&port->port_lock, flags);
 766         status = kfifo_put(&port->port_write_buf, ch);
 767         spin_unlock_irqrestore(&port->port_lock, flags);
 768
 769         return status;
 770 }
 771
 772 static void gs_flush_chars(struct tty_struct *tty)
 773 {
 774         struct gs_port  *port = tty->driver_data;
 775         unsigned long   flags;
 776
 777         pr_vdebug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);
 778
 779         spin_lock_irqsave(&port->port_lock, flags);
 780         if (port->port_usb)
 781                 gs_start_tx(port);
 782         spin_unlock_irqrestore(&port->port_lock, flags);
 783 }
 784
 785 static unsigned int gs_write_room(struct tty_struct *tty)
 786 {
 787         struct gs_port  *port = tty->driver_data;
 788         unsigned long   flags;
 789         unsigned int room = 0;
 790
 791         spin_lock_irqsave(&port->port_lock, flags);
 792         if (port->port_usb)
 793                 room = kfifo_avail(&port->port_write_buf);
 794         spin_unlock_irqrestore(&port->port_lock, flags);
 795
 796         pr_vdebug("gs_write_room: (%d,%p) room=%u\n",
 797                 port->port_num, tty, room);
 798
 799         return room;
 800 }
 801
 802 static unsigned int gs_chars_in_buffer(struct tty_struct *tty)
 803 {
 804         struct gs_port  *port = tty->driver_data;
 805         unsigned long   flags;
 806         unsigned int    chars;
 807
 808         spin_lock_irqsave(&port->port_lock, flags);
 809         chars = kfifo_len(&port->port_write_buf);
 810         spin_unlock_irqrestore(&port->port_lock, flags);
 811
 812         pr_vdebug("gs_chars_in_buffer: (%d,%p) chars=%u\n",
 813                 port->port_num, tty, chars);
 814
 815         return chars;
 816 }
 817
 818 /* undo side effects of setting TTY_THROTTLED */
 819 static void gs_unthrottle(struct tty_struct *tty)
 820 {
 821         struct gs_port          *port = tty->driver_data;
 822         unsigned long           flags;
 823
 824         spin_lock_irqsave(&port->port_lock, flags);
 825         if (port->port_usb) {
 826                 /* Kickstart read queue processing.  We don't do xon/xoff,
 827                  * rts/cts, or other handshaking with the host, but if the
 828                  * read queue backs up enough we'll be NAKing OUT packets.
 829                  */
 830                 pr_vdebug("ttyGS%d: unthrottle\n", port->port_num);
 831                 schedule_delayed_work(&port->push, 0);
 832         }
 833         spin_unlock_irqrestore(&port->port_lock, flags);
 834 }
 835
 836 static int gs_break_ctl(struct tty_struct *tty, int duration)
 837 {
 838         struct gs_port  *port = tty->driver_data;
 839         int             status = 0;
 840         struct gserial  *gser;
 841
 842         pr_vdebug("gs_break_ctl: ttyGS%d, send break (%d) \n",
 843                         port->port_num, duration);
 844
 845         spin_lock_irq(&port->port_lock);
 846         gser = port->port_usb;
 847         if (gser && gser->send_break)
 848                 status = gser->send_break(gser, duration);
 849         spin_unlock_irq(&port->port_lock);
 850
 851         return status;
 852 }
 853
 854 static const struct tty_operations gs_tty_ops = {
 855         .open =                 gs_open,
 856         .close =                gs_close,
 857         .write =                gs_write,
 858         .put_char =             gs_put_char,
 859         .flush_chars =          gs_flush_chars,
 860         .write_room =           gs_write_room,
 861         .chars_in_buffer =      gs_chars_in_buffer,
 862         .unthrottle =           gs_unthrottle,
 863         .break_ctl =            gs_break_ctl,
 864 };
 865
 866 /*-------------------------------------------------------------------------*/
 867
 868 static struct tty_driver *gs_tty_driver;
 869
 870 #ifdef CONFIG_U_SERIAL_CONSOLE
 871
 872 static void gs_console_complete_out(struct usb_ep *ep, struct usb_request *req)
 873 {
 874         struct gs_console *cons = req->context;
 875
 876         switch (req->status) {
 877         default:
 878                 pr_warn("%s: unexpected %s status %d\n",
 879                         __func__, ep->name, req->status);
 880                 fallthrough;
 881         case 0:
 882                 /* normal completion */
 883                 spin_lock(&cons->lock);
 884                 req->length = 0;
 885                 schedule_work(&cons->work);
 886                 spin_unlock(&cons->lock);
 887                 break;
 888         case -ECONNRESET:
 889         case -ESHUTDOWN:
 890                 /* disconnect */
 891                 pr_vdebug("%s: %s shutdown\n", __func__, ep->name);
 892                 break;
 893         }
 894 }
 895
 896 static void __gs_console_push(struct gs_console *cons)
 897 {
 898         struct usb_request *req = cons->req;
 899         struct usb_ep *ep;
 900         size_t size;
 901
 902         if (!req)
 903                 return; /* disconnected */
 904
 905         if (req->length)
 906                 return; /* busy */
 907
 908         ep = cons->console.data;
 909         size = kfifo_out(&cons->buf, req->buf, ep->maxpacket);
 910         if (!size)
 911                 return;
 912
 913         if (cons->missed && ep->maxpacket >= 64) {
 914                 char buf[64];
 915                 size_t len;
 916
 917                 len = sprintf(buf, "\n[missed %zu bytes]\n", cons->missed);
 918                 kfifo_in(&cons->buf, buf, len);
 919                 cons->missed = 0;
 920         }
 921
 922         req->length = size;
 923
 924         spin_unlock_irq(&cons->lock);
 925         if (usb_ep_queue(ep, req, GFP_ATOMIC))
 926                 req->length = 0;
 927         spin_lock_irq(&cons->lock);
 928 }
 929
 930 static void gs_console_work(struct work_struct *work)
 931 {
 932         struct gs_console *cons = container_of(work, struct gs_console, work);
 933
 934         spin_lock_irq(&cons->lock);
 935
 936         __gs_console_push(cons);
 937
 938         spin_unlock_irq(&cons->lock);
 939 }
 940
 941 static void gs_console_write(struct console *co,
 942                              const char *buf, unsigned count)
 943 {
 944         struct gs_console *cons = container_of(co, struct gs_console, console);
 945         unsigned long flags;
 946         size_t n;
 947
 948         spin_lock_irqsave(&cons->lock, flags);
 949
 950         n = kfifo_in(&cons->buf, buf, count);
 951         if (n < count)
 952                 cons->missed += count - n;
 953
 954         if (cons->req && !cons->req->length)
 955                 schedule_work(&cons->work);
 956
 957         spin_unlock_irqrestore(&cons->lock, flags);
 958 }
 959
 960 static struct tty_driver *gs_console_device(struct console *co, int *index)
 961 {
 962         *index = co->index;
 963         return gs_tty_driver;
 964 }
 965
 966 static int gs_console_connect(struct gs_port *port)
 967 {
 968         struct gs_console *cons = port->console;
 969         struct usb_request *req;
 970         struct usb_ep *ep;
 971
 972         if (!cons)
 973                 return 0;
 974
 975         ep = port->port_usb->in;
 976         req = gs_alloc_req(ep, ep->maxpacket, GFP_ATOMIC);
 977         if (!req)
 978                 return -ENOMEM;
 979         req->complete = gs_console_complete_out;
 980         req->context = cons;
 981         req->length = 0;
 982
 983         spin_lock(&cons->lock);
 984         cons->req = req;
 985         cons->console.data = ep;
 986         spin_unlock(&cons->lock);
 987
 988         pr_debug("ttyGS%d: console connected!\n", port->port_num);
 989
 990         schedule_work(&cons->work);
 991
 992         return 0;
 993 }
 994
 995 static void gs_console_disconnect(struct gs_port *port)
 996 {
 997         struct gs_console *cons = port->console;
 998         struct usb_request *req;
 999         struct usb_ep *ep;
1000
1001         if (!cons)
1002                 return;
1003
1004         spin_lock(&cons->lock);
1005
1006         req = cons->req;
1007         ep = cons->console.data;
1008         cons->req = NULL;
1009
1010         spin_unlock(&cons->lock);
1011
1012         if (!req)
1013                 return;
1014
1015         usb_ep_dequeue(ep, req);
1016         gs_free_req(ep, req);
1017 }
1018
1019 static int gs_console_init(struct gs_port *port)
1020 {
1021         struct gs_console *cons;
1022         int err;
1023
1024         if (port->console)
1025                 return 0;
1026
1027         cons = kzalloc(sizeof(*port->console), GFP_KERNEL);
1028         if (!cons)
1029                 return -ENOMEM;
1030
1031         strcpy(cons->console.name, "ttyGS");
1032         cons->console.write = gs_console_write;
1033         cons->console.device = gs_console_device;
1034         cons->console.flags = CON_PRINTBUFFER;
1035         cons->console.index = port->port_num;
1036
1037         INIT_WORK(&cons->work, gs_console_work);
1038         spin_lock_init(&cons->lock);
1039
1040         err = kfifo_alloc(&cons->buf, GS_CONSOLE_BUF_SIZE, GFP_KERNEL);
1041         if (err) {
1042                 pr_err("ttyGS%d: allocate console buffer failed\n", port->port_num);
1043                 kfree(cons);
1044                 return err;
1045         }
1046
1047         port->console = cons;
1048         register_console(&cons->console);
1049
1050         spin_lock_irq(&port->port_lock);
1051         if (port->port_usb)
1052                 gs_console_connect(port);
1053         spin_unlock_irq(&port->port_lock);
1054
1055         return 0;
1056 }
1057
1058 static void gs_console_exit(struct gs_port *port)
1059 {
1060         struct gs_console *cons = port->console;
1061
1062         if (!cons)
1063                 return;
1064
1065         unregister_console(&cons->console);
1066
1067         spin_lock_irq(&port->port_lock);
1068         if (cons->req)
1069                 gs_console_disconnect(port);
1070         spin_unlock_irq(&port->port_lock);
1071
1072         cancel_work_sync(&cons->work);
1073         kfifo_free(&cons->buf);
1074         kfree(cons);
1075         port->console = NULL;
1076 }
1077
1078 ssize_t gserial_set_console(unsigned char port_num, const char *page, size_t count)
1079 {
1080         struct gs_port *port;
1081         bool enable;
1082         int ret;
1083
1084         ret = kstrtobool(page, &enable);
1085         if (ret)
1086                 return ret;
1087
1088         mutex_lock(&ports[port_num].lock);
1089         port = ports[port_num].port;
1090
1091         if (WARN_ON(port == NULL)) {
1092                 ret = -ENXIO;
1093                 goto out;
1094         }
1095
1096         if (enable)
1097                 ret = gs_console_init(port);
1098         else
1099                 gs_console_exit(port);
1100 out:
1101         mutex_unlock(&ports[port_num].lock);
1102
1103         return ret < 0 ? ret : count;
1104 }
1105 EXPORT_SYMBOL_GPL(gserial_set_console);
1106
1107 ssize_t gserial_get_console(unsigned char port_num, char *page)
1108 {
1109         struct gs_port *port;
1110         ssize_t ret;
1111
1112         mutex_lock(&ports[port_num].lock);
1113         port = ports[port_num].port;
1114
1115         if (WARN_ON(port == NULL))
1116                 ret = -ENXIO;
1117         else
1118                 ret = sprintf(page, "%u\n", !!port->console);
1119
1120         mutex_unlock(&ports[port_num].lock);
1121
1122         return ret;
1123 }
1124 EXPORT_SYMBOL_GPL(gserial_get_console);
1125
1126 #else
1127
1128 static int gs_console_connect(struct gs_port *port)
1129 {
1130         return 0;
1131 }
1132
1133 static void gs_console_disconnect(struct gs_port *port)
1134 {
1135 }
1136
1137 static int gs_console_init(struct gs_port *port)
1138 {
1139         return -ENOSYS;
1140 }
1141
1142 static void gs_console_exit(struct gs_port *port)
1143 {
1144 }
1145
1146 #endif
1147
1148 static int
1149 gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)
1150 {
1151         struct gs_port  *port;
1152         int             ret = 0;
1153
1154         mutex_lock(&ports[port_num].lock);
1155         if (ports[port_num].port) {
1156                 ret = -EBUSY;
1157                 goto out;
1158         }
1159
1160         port = kzalloc(sizeof(struct gs_port), GFP_KERNEL);
1161         if (port == NULL) {
1162                 ret = -ENOMEM;
1163                 goto out;
1164         }
1165
1166         tty_port_init(&port->port);
1167         spin_lock_init(&port->port_lock);
1168         init_waitqueue_head(&port->drain_wait);
1169         init_waitqueue_head(&port->close_wait);
1170
1171         INIT_DELAYED_WORK(&port->push, gs_rx_push);
1172
1173         INIT_LIST_HEAD(&port->read_pool);
1174         INIT_LIST_HEAD(&port->read_queue);
1175         INIT_LIST_HEAD(&port->write_pool);
1176
1177         port->port_num = port_num;
1178         port->port_line_coding = *coding;
1179
1180         ports[port_num].port = port;
1181 out:
1182         mutex_unlock(&ports[port_num].lock);
1183         return ret;
1184 }
1185
1186 static int gs_closed(struct gs_port *port)
1187 {
1188         int cond;
1189
1190         spin_lock_irq(&port->port_lock);
1191         cond = port->port.count == 0;
1192         spin_unlock_irq(&port->port_lock);
1193
1194         return cond;
1195 }
1196
1197 static void gserial_free_port(struct gs_port *port)
1198 {
1199         cancel_delayed_work_sync(&port->push);
1200         /* wait for old opens to finish */
1201         wait_event(port->close_wait, gs_closed(port));
1202         WARN_ON(port->port_usb != NULL);
1203         tty_port_destroy(&port->port);
1204         kfree(port);
1205 }
1206
1207 void gserial_free_line(unsigned char port_num)
1208 {
1209         struct gs_port  *port;
1210
1211         mutex_lock(&ports[port_num].lock);
1212         if (!ports[port_num].port) {
1213                 mutex_unlock(&ports[port_num].lock);
1214                 return;
1215         }
1216         port = ports[port_num].port;
1217         gs_console_exit(port);
1218         ports[port_num].port = NULL;
1219         mutex_unlock(&ports[port_num].lock);
1220
1221         gserial_free_port(port);
1222         tty_unregister_device(gs_tty_driver, port_num);
1223 }
1224 EXPORT_SYMBOL_GPL(gserial_free_line);
1225
1226 int gserial_alloc_line_no_console(unsigned char *line_num)
1227 {
1228         struct usb_cdc_line_coding      coding;
1229         struct gs_port                  *port;
1230         struct device                   *tty_dev;
1231         int                             ret;
1232         int                             port_num;
1233
1234         coding.dwDTERate = cpu_to_le32(9600);
1235         coding.bCharFormat = 8;
1236         coding.bParityType = USB_CDC_NO_PARITY;
1237         coding.bDataBits = USB_CDC_1_STOP_BITS;
1238
1239         for (port_num = 0; port_num < MAX_U_SERIAL_PORTS; port_num++) {
1240                 ret = gs_port_alloc(port_num, &coding);
1241                 if (ret == -EBUSY)
1242                         continue;
1243                 if (ret)
1244                         return ret;
1245                 break;
1246         }
1247         if (ret)
1248                 return ret;
1249
1250         /* ... and sysfs class devices, so mdev/udev make /dev/ttyGS* */
1251
1252         port = ports[port_num].port;
1253         tty_dev = tty_port_register_device(&port->port,
1254                         gs_tty_driver, port_num, NULL);
1255         if (IS_ERR(tty_dev)) {
1256                 pr_err("%s: failed to register tty for port %d, err %ld\n",
1257                                 __func__, port_num, PTR_ERR(tty_dev));
1258
1259                 ret = PTR_ERR(tty_dev);
1260                 mutex_lock(&ports[port_num].lock);
1261                 ports[port_num].port = NULL;
1262                 mutex_unlock(&ports[port_num].lock);
1263                 gserial_free_port(port);
1264                 goto err;
1265         }
1266         *line_num = port_num;
1267 err:
1268         return ret;
1269 }
1270 EXPORT_SYMBOL_GPL(gserial_alloc_line_no_console);
1271
1272 int gserial_alloc_line(unsigned char *line_num)
1273 {
1274         int ret = gserial_alloc_line_no_console(line_num);
1275
1276         if (!ret && !*line_num)
1277                 gs_console_init(ports[*line_num].port);
1278
1279         return ret;
1280 }
1281 EXPORT_SYMBOL_GPL(gserial_alloc_line);
1282
1283 /**
1284  * gserial_connect - notify TTY I/O glue that USB link is active
1285  * @gser: the function, set up with endpoints and descriptors
1286  * @port_num: which port is active
1287  * Context: any (usually from irq)
1288  *
1289  * This is called activate endpoints and let the TTY layer know that
1290  * the connection is active ... not unlike "carrier detect".  It won't
1291  * necessarily start I/O queues; unless the TTY is held open by any
1292  * task, there would be no point.  However, the endpoints will be
1293  * activated so the USB host can perform I/O, subject to basic USB
1294  * hardware flow control.
1295  *
1296  * Caller needs to have set up the endpoints and USB function in @dev
1297  * before calling this, as well as the appropriate (speed-specific)
1298  * endpoint descriptors, and also have allocate @port_num by calling
1299  * @gserial_alloc_line().
1300  *
1301  * Returns negative errno or zero.
1302  * On success, ep->driver_data will be overwritten.
1303  */
1304 int gserial_connect(struct gserial *gser, u8 port_num)
1305 {
1306         struct gs_port  *port;
1307         unsigned long   flags;
1308         int             status;
1309
1310         if (port_num >= MAX_U_SERIAL_PORTS)
1311                 return -ENXIO;
1312
1313         port = ports[port_num].port;
1314         if (!port) {
1315                 pr_err("serial line %d not allocated.\n", port_num);
1316                 return -EINVAL;
1317         }
1318         if (port->port_usb) {
1319                 pr_err("serial line %d is in use.\n", port_num);
1320                 return -EBUSY;
1321         }
1322
1323         /* activate the endpoints */
1324         status = usb_ep_enable(gser->in);
1325         if (status < 0)
1326                 return status;
1327         gser->in->driver_data = port;
1328
1329         status = usb_ep_enable(gser->out);
1330         if (status < 0)
1331                 goto fail_out;
1332         gser->out->driver_data = port;
1333
1334         /* then tell the tty glue that I/O can work */
1335         spin_lock_irqsave(&port->port_lock, flags);
1336         gser->ioport = port;
1337         port->port_usb = gser;
1338
1339         /* REVISIT unclear how best to handle this state...
1340          * we don't really couple it with the Linux TTY.
1341          */
1342         gser->port_line_coding = port->port_line_coding;
1343
1344         /* REVISIT if waiting on "carrier detect", signal. */
1345
1346         /* if it's already open, start I/O ... and notify the serial
1347          * protocol about open/close status (connect/disconnect).
1348          */
1349         if (port->port.count) {
1350                 pr_debug("gserial_connect: start ttyGS%d\n", port->port_num);
1351                 gs_start_io(port);
1352                 if (gser->connect)
1353                         gser->connect(gser);
1354         } else {
1355                 if (gser->disconnect)
1356                         gser->disconnect(gser);
1357         }
1358
1359         status = gs_console_connect(port);
1360         spin_unlock_irqrestore(&port->port_lock, flags);
1361
1362         return status;
1363
1364 fail_out:
1365         usb_ep_disable(gser->in);
1366         return status;
1367 }
1368 EXPORT_SYMBOL_GPL(gserial_connect);
1369 /**
1370  * gserial_disconnect - notify TTY I/O glue that USB link is inactive
1371  * @gser: the function, on which gserial_connect() was called
1372  * Context: any (usually from irq)
1373  *
1374  * This is called to deactivate endpoints and let the TTY layer know
1375  * that the connection went inactive ... not unlike "hangup".
1376  *
1377  * On return, the state is as if gserial_connect() had never been called;
1378  * there is no active USB I/O on these endpoints.
1379  */
1380 void gserial_disconnect(struct gserial *gser)
1381 {
1382         struct gs_port  *port = gser->ioport;
1383         unsigned long   flags;
1384
1385         if (!port)
1386                 return;
1387
1388         spin_lock_irqsave(&serial_port_lock, flags);
1389
1390         /* tell the TTY glue not to do I/O here any more */
1391         spin_lock(&port->port_lock);
1392
1393         gs_console_disconnect(port);
1394
1395         /* REVISIT as above: how best to track this? */
1396         port->port_line_coding = gser->port_line_coding;
1397
1398         port->port_usb = NULL;
1399         gser->ioport = NULL;
1400         if (port->port.count > 0) {
1401                 wake_up_interruptible(&port->drain_wait);
1402                 if (port->port.tty)
1403                         tty_hangup(port->port.tty);
1404         }
1405         port->suspended = false;
1406         spin_unlock(&port->port_lock);
1407         spin_unlock_irqrestore(&serial_port_lock, flags);
1408
1409         /* disable endpoints, aborting down any active I/O */
1410         usb_ep_disable(gser->out);
1411         usb_ep_disable(gser->in);
1412
1413         /* finally, free any unused/unusable I/O buffers */
1414         spin_lock_irqsave(&port->port_lock, flags);
1415         if (port->port.count == 0)
1416                 kfifo_free(&port->port_write_buf);
1417         gs_free_requests(gser->out, &port->read_pool, NULL);
1418         gs_free_requests(gser->out, &port->read_queue, NULL);
1419         gs_free_requests(gser->in, &port->write_pool, NULL);
1420
1421         port->read_allocated = port->read_started =
1422                 port->write_allocated = port->write_started = 0;
1423
1424         spin_unlock_irqrestore(&port->port_lock, flags);
1425 }
1426 EXPORT_SYMBOL_GPL(gserial_disconnect);
1427
1428 void gserial_suspend(struct gserial *gser)
1429 {
1430         struct gs_port  *port;
1431         unsigned long   flags;
1432
1433         spin_lock_irqsave(&serial_port_lock, flags);
1434         port = gser->ioport;
1435
1436         if (!port) {
1437                 spin_unlock_irqrestore(&serial_port_lock, flags);
1438                 return;
1439         }
1440
1441         spin_lock(&port->port_lock);
1442         spin_unlock(&serial_port_lock);
1443         port->suspended = true;
1444         spin_unlock_irqrestore(&port->port_lock, flags);
1445 }
1446 EXPORT_SYMBOL_GPL(gserial_suspend);
1447
1448 void gserial_resume(struct gserial *gser)
1449 {
1450         struct gs_port *port;
1451         unsigned long   flags;
1452
1453         spin_lock_irqsave(&serial_port_lock, flags);
1454         port = gser->ioport;
1455
1456         if (!port) {
1457                 spin_unlock_irqrestore(&serial_port_lock, flags);
1458                 return;
1459         }
1460
1461         spin_lock(&port->port_lock);
1462         spin_unlock(&serial_port_lock);
1463         port->suspended = false;
1464         if (!port->start_delayed) {
1465                 spin_unlock_irqrestore(&port->port_lock, flags);
1466                 return;
1467         }
1468
1469         pr_debug("delayed start ttyGS%d\n", port->port_num);
1470         gs_start_io(port);
1471         if (gser->connect)
1472                 gser->connect(gser);
1473         port->start_delayed = false;
1474         spin_unlock_irqrestore(&port->port_lock, flags);
1475 }
1476 EXPORT_SYMBOL_GPL(gserial_resume);
1477
1478 static int __init userial_init(void)
1479 {
1480         struct tty_driver *driver;
1481         unsigned                        i;
1482         int                             status;
1483
1484         driver = tty_alloc_driver(MAX_U_SERIAL_PORTS, TTY_DRIVER_REAL_RAW |
1485                         TTY_DRIVER_DYNAMIC_DEV);
1486         if (IS_ERR(driver))
1487                 return PTR_ERR(driver);
1488
1489         driver->driver_name = "g_serial";
1490         driver->name = "ttyGS";
1491         /* uses dynamically assigned dev_t values */
1492
1493         driver->type = TTY_DRIVER_TYPE_SERIAL;
1494         driver->subtype = SERIAL_TYPE_NORMAL;
1495         driver->init_termios = tty_std_termios;
1496
1497         /* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
1498          * MS-Windows.  Otherwise, most of these flags shouldn't affect
1499          * anything unless we were to actually hook up to a serial line.
1500          */
1501         driver->init_termios.c_cflag =
1502                         B9600 | CS8 | CREAD | HUPCL | CLOCAL;
1503         driver->init_termios.c_ispeed = 9600;
1504         driver->init_termios.c_ospeed = 9600;
1505
1506         tty_set_operations(driver, &gs_tty_ops);
1507         for (i = 0; i < MAX_U_SERIAL_PORTS; i++)
1508                 mutex_init(&ports[i].lock);
1509
1510         /* export the driver ... */
1511         status = tty_register_driver(driver);
1512         if (status) {
1513                 pr_err("%s: cannot register, err %d\n",
1514                                 __func__, status);
1515                 goto fail;
1516         }
1517
1518         gs_tty_driver = driver;
1519
1520         pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
1521                         MAX_U_SERIAL_PORTS,
1522                         (MAX_U_SERIAL_PORTS == 1) ? "" : "s");
1523
1524         return status;
1525 fail:
1526         tty_driver_kref_put(driver);
1527         return status;
1528 }
1529 module_init(userial_init);
1530
1531 static void __exit userial_cleanup(void)
1532 {
1533         tty_unregister_driver(gs_tty_driver);
1534         tty_driver_kref_put(gs_tty_driver);
1535         gs_tty_driver = NULL;
1536 }
1537 module_exit(userial_cleanup);
1538
1539 MODULE_LICENSE("GPL");