kernel/drivers/staging/gdm724x/gdm_mux.c

   1 /*
   2  * Copyright (c) 2012 GCT Semiconductor, Inc. All rights reserved.
   3  *
   4  * This software is licensed under the terms of the GNU General Public
   5  * License version 2, as published by the Free Software Foundation, and
   6  * may be copied, distributed, and modified under those terms.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/usb.h>
  19 #include <linux/errno.h>
  20 #include <linux/init.h>
  21 #include <linux/tty.h>
  22 #include <linux/tty_driver.h>
  23 #include <linux/tty_flip.h>
  24 #include <linux/slab.h>
  25 #include <linux/usb/cdc.h>
  26
  27 #include "gdm_mux.h"
  28
  29 static struct workqueue_struct *mux_rx_wq;
  30
  31 static u16 packet_type[TTY_MAX_COUNT] = {0xF011, 0xF010};
  32
  33 #define USB_DEVICE_CDC_DATA(vid, pid) \
  34         .match_flags = \
  35                 USB_DEVICE_ID_MATCH_DEVICE |\
  36                 USB_DEVICE_ID_MATCH_INT_CLASS |\
  37                 USB_DEVICE_ID_MATCH_INT_SUBCLASS,\
  38         .idVendor = vid,\
  39         .idProduct = pid,\
  40         .bInterfaceClass = USB_CLASS_COMM,\
  41         .bInterfaceSubClass = USB_CDC_SUBCLASS_ACM
  42
  43 static const struct usb_device_id id_table[] = {
  44         { USB_DEVICE_CDC_DATA(0x1076, 0x8000) }, /* GCT GDM7240 */
  45         { USB_DEVICE_CDC_DATA(0x1076, 0x8f00) }, /* GCT GDM7243 */
  46         { USB_DEVICE_CDC_DATA(0x1076, 0x9000) }, /* GCT GDM7243 */
  47         { USB_DEVICE_CDC_DATA(0x1d74, 0x2300) }, /* LGIT Phoenix */
  48         {}
  49 };
  50
  51 MODULE_DEVICE_TABLE(usb, id_table);
  52
  53 static int packet_type_to_index(u16 packetType)
  54 {
  55         int i;
  56
  57         for (i = 0; i < TTY_MAX_COUNT; i++) {
  58                 if (packet_type[i] == packetType)
  59                         return i;
  60         }
  61
  62         return -1;
  63 }
  64
  65 static struct mux_tx *alloc_mux_tx(int len)
  66 {
  67         struct mux_tx *t = NULL;
  68
  69         t = kzalloc(sizeof(*t), GFP_ATOMIC);
  70         if (!t)
  71                 return NULL;
  72
  73         t->urb = usb_alloc_urb(0, GFP_ATOMIC);
  74         t->buf = kmalloc(MUX_TX_MAX_SIZE, GFP_ATOMIC);
  75         if (!t->urb || !t->buf) {
  76                 usb_free_urb(t->urb);
  77                 kfree(t->buf);
  78                 kfree(t);
  79                 return NULL;
  80         }
  81
  82         return t;
  83 }
  84
  85 static void free_mux_tx(struct mux_tx *t)
  86 {
  87         if (t) {
  88                 usb_free_urb(t->urb);
  89                 kfree(t->buf);
  90                 kfree(t);
  91         }
  92 }
  93
  94 static struct mux_rx *alloc_mux_rx(void)
  95 {
  96         struct mux_rx *r = NULL;
  97
  98         r = kzalloc(sizeof(*r), GFP_KERNEL);
  99         if (!r)
 100                 return NULL;
 101
 102         r->urb = usb_alloc_urb(0, GFP_KERNEL);
 103         r->buf = kmalloc(MUX_RX_MAX_SIZE, GFP_KERNEL);
 104         if (!r->urb || !r->buf) {
 105                 usb_free_urb(r->urb);
 106                 kfree(r->buf);
 107                 kfree(r);
 108                 return NULL;
 109         }
 110
 111         return r;
 112 }
 113
 114 static void free_mux_rx(struct mux_rx *r)
 115 {
 116         if (r) {
 117                 usb_free_urb(r->urb);
 118                 kfree(r->buf);
 119                 kfree(r);
 120         }
 121 }
 122
 123 static struct mux_rx *get_rx_struct(struct rx_cxt *rx)
 124 {
 125         struct mux_rx *r;
 126         unsigned long flags;
 127
 128         spin_lock_irqsave(&rx->free_list_lock, flags);
 129
 130         if (list_empty(&rx->rx_free_list)) {
 131                 spin_unlock_irqrestore(&rx->free_list_lock, flags);
 132                 return NULL;
 133         }
 134
 135         r = list_entry(rx->rx_free_list.prev, struct mux_rx, free_list);
 136         list_del(&r->free_list);
 137
 138         spin_unlock_irqrestore(&rx->free_list_lock, flags);
 139
 140         return r;
 141 }
 142
 143 static void put_rx_struct(struct rx_cxt *rx, struct mux_rx *r)
 144 {
 145         unsigned long flags;
 146
 147         spin_lock_irqsave(&rx->free_list_lock, flags);
 148         list_add_tail(&r->free_list, &rx->rx_free_list);
 149         spin_unlock_irqrestore(&rx->free_list_lock, flags);
 150 }
 151
 152 static int up_to_host(struct mux_rx *r)
 153 {
 154         struct mux_dev *mux_dev = r->mux_dev;
 155         struct mux_pkt_header *mux_header;
 156         unsigned int start_flag;
 157         unsigned int payload_size;
 158         unsigned short packet_type;
 159         int total_len;
 160         u32 packet_size_sum = r->offset;
 161         int index;
 162         int ret = TO_HOST_INVALID_PACKET;
 163         int len = r->len;
 164
 165         while (1) {
 166                 mux_header = (struct mux_pkt_header *)(r->buf +
 167                                                        packet_size_sum);
 168                 start_flag = __le32_to_cpu(mux_header->start_flag);
 169                 payload_size = __le32_to_cpu(mux_header->payload_size);
 170                 packet_type = __le16_to_cpu(mux_header->packet_type);
 171
 172                 if (start_flag != START_FLAG) {
 173                         pr_err("invalid START_FLAG %x\n", start_flag);
 174                         break;
 175                 }
 176
 177                 total_len = ALIGN(MUX_HEADER_SIZE + payload_size, 4);
 178
 179                 if (len - packet_size_sum <
 180                         total_len) {
 181                         pr_err("invalid payload : %d %d %04x\n",
 182                                payload_size, len, packet_type);
 183                         break;
 184                 }
 185
 186                 index = packet_type_to_index(packet_type);
 187                 if (index < 0) {
 188                         pr_err("invalid index %d\n", index);
 189                         break;
 190                 }
 191
 192                 ret = r->callback(mux_header->data,
 193                                 payload_size,
 194                                 index,
 195                                 mux_dev->tty_dev,
 196                                 RECV_PACKET_PROCESS_CONTINUE
 197                                 );
 198                 if (ret == TO_HOST_BUFFER_REQUEST_FAIL) {
 199                         r->offset += packet_size_sum;
 200                         break;
 201                 }
 202
 203                 packet_size_sum += total_len;
 204                 if (len - packet_size_sum <= MUX_HEADER_SIZE + 2) {
 205                         ret = r->callback(NULL,
 206                                         0,
 207                                         index,
 208                                         mux_dev->tty_dev,
 209                                         RECV_PACKET_PROCESS_COMPLETE
 210                                         );
 211                         break;
 212                 }
 213         }
 214
 215         return ret;
 216 }
 217
 218 static void do_rx(struct work_struct *work)
 219 {
 220         struct mux_dev *mux_dev =
 221                 container_of(work, struct mux_dev, work_rx.work);
 222         struct mux_rx *r;
 223         struct rx_cxt *rx = &mux_dev->rx;
 224         unsigned long flags;
 225         int ret = 0;
 226
 227         while (1) {
 228                 spin_lock_irqsave(&rx->to_host_lock, flags);
 229                 if (list_empty(&rx->to_host_list)) {
 230                         spin_unlock_irqrestore(&rx->to_host_lock, flags);
 231                         break;
 232                 }
 233                 r = list_entry(rx->to_host_list.next, struct mux_rx,
 234                                to_host_list);
 235                 list_del(&r->to_host_list);
 236                 spin_unlock_irqrestore(&rx->to_host_lock, flags);
 237
 238                 ret = up_to_host(r);
 239                 if (ret == TO_HOST_BUFFER_REQUEST_FAIL)
 240                         pr_err("failed to send mux data to host\n");
 241                 else
 242                         put_rx_struct(rx, r);
 243         }
 244 }
 245
 246 static void remove_rx_submit_list(struct mux_rx *r, struct rx_cxt *rx)
 247 {
 248         unsigned long flags;
 249         struct mux_rx   *r_remove, *r_remove_next;
 250
 251         spin_lock_irqsave(&rx->submit_list_lock, flags);
 252         list_for_each_entry_safe(r_remove, r_remove_next, &rx->rx_submit_list,
 253                                  rx_submit_list) {
 254                 if (r == r_remove)
 255                         list_del(&r->rx_submit_list);
 256         }
 257         spin_unlock_irqrestore(&rx->submit_list_lock, flags);
 258 }
 259
 260 static void gdm_mux_rcv_complete(struct urb *urb)
 261 {
 262         struct mux_rx *r = urb->context;
 263         struct mux_dev *mux_dev = r->mux_dev;
 264         struct rx_cxt *rx = &mux_dev->rx;
 265         unsigned long flags;
 266
 267         remove_rx_submit_list(r, rx);
 268
 269         if (urb->status) {
 270                 if (mux_dev->usb_state == PM_NORMAL)
 271                         dev_err(&urb->dev->dev, "%s: urb status error %d\n",
 272                                 __func__, urb->status);
 273                 put_rx_struct(rx, r);
 274         } else {
 275                 r->len = r->urb->actual_length;
 276                 spin_lock_irqsave(&rx->to_host_lock, flags);
 277                 list_add_tail(&r->to_host_list, &rx->to_host_list);
 278                 queue_work(mux_rx_wq, &mux_dev->work_rx.work);
 279                 spin_unlock_irqrestore(&rx->to_host_lock, flags);
 280         }
 281 }
 282
 283 static int gdm_mux_recv(void *priv_dev, int (*cb)(void *data, int len,
 284                         int tty_index, struct tty_dev *tty_dev, int complete))
 285 {
 286         struct mux_dev *mux_dev = priv_dev;
 287         struct usb_device *usbdev = mux_dev->usbdev;
 288         struct mux_rx *r;
 289         struct rx_cxt *rx = &mux_dev->rx;
 290         unsigned long flags;
 291         int ret;
 292
 293         if (!usbdev) {
 294                 pr_err("device is disconnected\n");
 295                 return -ENODEV;
 296         }
 297
 298         r = get_rx_struct(rx);
 299         if (!r) {
 300                 pr_err("get_rx_struct fail\n");
 301                 return -ENOMEM;
 302         }
 303
 304         r->offset = 0;
 305         r->mux_dev = (void *)mux_dev;
 306         r->callback = cb;
 307         mux_dev->rx_cb = cb;
 308
 309         usb_fill_bulk_urb(r->urb,
 310                           usbdev,
 311                           usb_rcvbulkpipe(usbdev, 0x86),
 312                           r->buf,
 313                           MUX_RX_MAX_SIZE,
 314                           gdm_mux_rcv_complete,
 315                           r);
 316
 317         spin_lock_irqsave(&rx->submit_list_lock, flags);
 318         list_add_tail(&r->rx_submit_list, &rx->rx_submit_list);
 319         spin_unlock_irqrestore(&rx->submit_list_lock, flags);
 320
 321         ret = usb_submit_urb(r->urb, GFP_KERNEL);
 322
 323         if (ret) {
 324                 spin_lock_irqsave(&rx->submit_list_lock, flags);
 325                 list_del(&r->rx_submit_list);
 326                 spin_unlock_irqrestore(&rx->submit_list_lock, flags);
 327
 328                 put_rx_struct(rx, r);
 329
 330                 pr_err("usb_submit_urb ret=%d\n", ret);
 331         }
 332
 333         usb_mark_last_busy(usbdev);
 334
 335         return ret;
 336 }
 337
 338 static void gdm_mux_send_complete(struct urb *urb)
 339 {
 340         struct mux_tx *t = urb->context;
 341
 342         if (urb->status == -ECONNRESET) {
 343                 dev_info(&urb->dev->dev, "CONNRESET\n");
 344                 free_mux_tx(t);
 345                 return;
 346         }
 347
 348         if (t->callback)
 349                 t->callback(t->cb_data);
 350
 351         free_mux_tx(t);
 352 }
 353
 354 static int gdm_mux_send(void *priv_dev, void *data, int len, int tty_index,
 355                         void (*cb)(void *data), void *cb_data)
 356 {
 357         struct mux_dev *mux_dev = priv_dev;
 358         struct usb_device *usbdev = mux_dev->usbdev;
 359         struct mux_pkt_header *mux_header;
 360         struct mux_tx *t = NULL;
 361         static u32 seq_num = 1;
 362         int total_len;
 363         int ret;
 364         unsigned long flags;
 365
 366         if (mux_dev->usb_state == PM_SUSPEND) {
 367                 ret = usb_autopm_get_interface(mux_dev->intf);
 368                 if (!ret)
 369                         usb_autopm_put_interface(mux_dev->intf);
 370         }
 371
 372         spin_lock_irqsave(&mux_dev->write_lock, flags);
 373
 374         total_len = ALIGN(MUX_HEADER_SIZE + len, 4);
 375
 376         t = alloc_mux_tx(total_len);
 377         if (!t) {
 378                 pr_err("alloc_mux_tx fail\n");
 379                 spin_unlock_irqrestore(&mux_dev->write_lock, flags);
 380                 return -ENOMEM;
 381         }
 382
 383         mux_header = (struct mux_pkt_header *)t->buf;
 384         mux_header->start_flag = __cpu_to_le32(START_FLAG);
 385         mux_header->seq_num = __cpu_to_le32(seq_num++);
 386         mux_header->payload_size = __cpu_to_le32((u32)len);
 387         mux_header->packet_type = __cpu_to_le16(packet_type[tty_index]);
 388
 389         memcpy(t->buf + MUX_HEADER_SIZE, data, len);
 390         memset(t->buf + MUX_HEADER_SIZE + len, 0, total_len - MUX_HEADER_SIZE -
 391                len);
 392
 393         t->len = total_len;
 394         t->callback = cb;
 395         t->cb_data = cb_data;
 396
 397         usb_fill_bulk_urb(t->urb,
 398                           usbdev,
 399                           usb_sndbulkpipe(usbdev, 5),
 400                           t->buf,
 401                           total_len,
 402                           gdm_mux_send_complete,
 403                           t);
 404
 405         ret = usb_submit_urb(t->urb, GFP_ATOMIC);
 406
 407         spin_unlock_irqrestore(&mux_dev->write_lock, flags);
 408
 409         if (ret)
 410                 pr_err("usb_submit_urb Error: %d\n", ret);
 411
 412         usb_mark_last_busy(usbdev);
 413
 414         return ret;
 415 }
 416
 417 static int gdm_mux_send_control(void *priv_dev, int request, int value,
 418                                 void *buf, int len)
 419 {
 420         struct mux_dev *mux_dev = priv_dev;
 421         struct usb_device *usbdev = mux_dev->usbdev;
 422         int ret;
 423
 424         ret = usb_control_msg(usbdev,
 425                               usb_sndctrlpipe(usbdev, 0),
 426                               request,
 427                               USB_RT_ACM,
 428                               value,
 429                               2,
 430                               buf,
 431                               len,
 432                               5000
 433                              );
 434
 435         if (ret < 0)
 436                 pr_err("usb_control_msg error: %d\n", ret);
 437
 438         return ret < 0 ? ret : 0;
 439 }
 440
 441 static void release_usb(struct mux_dev *mux_dev)
 442 {
 443         struct rx_cxt           *rx = &mux_dev->rx;
 444         struct mux_rx           *r, *r_next;
 445         unsigned long           flags;
 446
 447         cancel_delayed_work(&mux_dev->work_rx);
 448
 449         spin_lock_irqsave(&rx->submit_list_lock, flags);
 450         list_for_each_entry_safe(r, r_next, &rx->rx_submit_list,
 451                                  rx_submit_list) {
 452                 spin_unlock_irqrestore(&rx->submit_list_lock, flags);
 453                 usb_kill_urb(r->urb);
 454                 spin_lock_irqsave(&rx->submit_list_lock, flags);
 455         }
 456         spin_unlock_irqrestore(&rx->submit_list_lock, flags);
 457
 458         spin_lock_irqsave(&rx->free_list_lock, flags);
 459         list_for_each_entry_safe(r, r_next, &rx->rx_free_list, free_list) {
 460                 list_del(&r->free_list);
 461                 free_mux_rx(r);
 462         }
 463         spin_unlock_irqrestore(&rx->free_list_lock, flags);
 464
 465         spin_lock_irqsave(&rx->to_host_lock, flags);
 466         list_for_each_entry_safe(r, r_next, &rx->to_host_list, to_host_list) {
 467                 if (r->mux_dev == (void *)mux_dev) {
 468                         list_del(&r->to_host_list);
 469                         free_mux_rx(r);
 470                 }
 471         }
 472         spin_unlock_irqrestore(&rx->to_host_lock, flags);
 473 }
 474
 475 static int init_usb(struct mux_dev *mux_dev)
 476 {
 477         struct mux_rx *r;
 478         struct rx_cxt *rx = &mux_dev->rx;
 479         int ret = 0;
 480         int i;
 481
 482         spin_lock_init(&mux_dev->write_lock);
 483         INIT_LIST_HEAD(&rx->to_host_list);
 484         INIT_LIST_HEAD(&rx->rx_submit_list);
 485         INIT_LIST_HEAD(&rx->rx_free_list);
 486         spin_lock_init(&rx->to_host_lock);
 487         spin_lock_init(&rx->submit_list_lock);
 488         spin_lock_init(&rx->free_list_lock);
 489
 490         for (i = 0; i < MAX_ISSUE_NUM * 2; i++) {
 491                 r = alloc_mux_rx();
 492                 if (!r) {
 493                         ret = -ENOMEM;
 494                         break;
 495                 }
 496
 497                 list_add(&r->free_list, &rx->rx_free_list);
 498         }
 499
 500         INIT_DELAYED_WORK(&mux_dev->work_rx, do_rx);
 501
 502         return ret;
 503 }
 504
 505 static int gdm_mux_probe(struct usb_interface *intf,
 506                          const struct usb_device_id *id)
 507 {
 508         struct mux_dev *mux_dev;
 509         struct tty_dev *tty_dev;
 510         u16 idVendor, idProduct;
 511         int bInterfaceNumber;
 512         int ret;
 513         int i;
 514         struct usb_device *usbdev = interface_to_usbdev(intf);
 515
 516         bInterfaceNumber = intf->cur_altsetting->desc.bInterfaceNumber;
 517
 518         idVendor = __le16_to_cpu(usbdev->descriptor.idVendor);
 519         idProduct = __le16_to_cpu(usbdev->descriptor.idProduct);
 520
 521         pr_info("mux vid = 0x%04x pid = 0x%04x\n", idVendor, idProduct);
 522
 523         if (bInterfaceNumber != 2)
 524                 return -ENODEV;
 525
 526         mux_dev = kzalloc(sizeof(*mux_dev), GFP_KERNEL);
 527         if (!mux_dev)
 528                 return -ENOMEM;
 529
 530         tty_dev = kzalloc(sizeof(*tty_dev), GFP_KERNEL);
 531         if (!tty_dev) {
 532                 ret = -ENOMEM;
 533                 goto err_free_mux;
 534         }
 535
 536         mux_dev->usbdev = usbdev;
 537         mux_dev->control_intf = intf;
 538
 539         ret = init_usb(mux_dev);
 540         if (ret)
 541                 goto err_free_usb;
 542
 543         tty_dev->priv_dev = (void *)mux_dev;
 544         tty_dev->send_func = gdm_mux_send;
 545         tty_dev->recv_func = gdm_mux_recv;
 546         tty_dev->send_control = gdm_mux_send_control;
 547
 548         ret = register_lte_tty_device(tty_dev, &intf->dev);
 549         if (ret)
 550                 goto err_unregister_tty;
 551
 552         for (i = 0; i < TTY_MAX_COUNT; i++)
 553                 mux_dev->tty_dev = tty_dev;
 554
 555         mux_dev->intf = intf;
 556         mux_dev->usb_state = PM_NORMAL;
 557
 558         usb_get_dev(usbdev);
 559         usb_set_intfdata(intf, tty_dev);
 560
 561         return 0;
 562
 563 err_unregister_tty:
 564         unregister_lte_tty_device(tty_dev);
 565 err_free_usb:
 566         release_usb(mux_dev);
 567         kfree(tty_dev);
 568 err_free_mux:
 569         kfree(mux_dev);
 570
 571         return ret;
 572 }
 573
 574 static void gdm_mux_disconnect(struct usb_interface *intf)
 575 {
 576         struct tty_dev *tty_dev;
 577         struct mux_dev *mux_dev;
 578         struct usb_device *usbdev = interface_to_usbdev(intf);
 579
 580         tty_dev = usb_get_intfdata(intf);
 581
 582         mux_dev = tty_dev->priv_dev;
 583
 584         release_usb(mux_dev);
 585         unregister_lte_tty_device(tty_dev);
 586
 587         kfree(mux_dev);
 588         kfree(tty_dev);
 589
 590         usb_put_dev(usbdev);
 591 }
 592
 593 static int gdm_mux_suspend(struct usb_interface *intf, pm_message_t pm_msg)
 594 {
 595         struct tty_dev *tty_dev;
 596         struct mux_dev *mux_dev;
 597         struct rx_cxt *rx;
 598         struct mux_rx *r, *r_next;
 599         unsigned long flags;
 600
 601         tty_dev = usb_get_intfdata(intf);
 602         mux_dev = tty_dev->priv_dev;
 603         rx = &mux_dev->rx;
 604
 605         if (mux_dev->usb_state != PM_NORMAL) {
 606                 dev_err(intf->usb_dev, "usb suspend - invalid state\n");
 607                 return -1;
 608         }
 609
 610         mux_dev->usb_state = PM_SUSPEND;
 611
 612         spin_lock_irqsave(&rx->submit_list_lock, flags);
 613         list_for_each_entry_safe(r, r_next, &rx->rx_submit_list,
 614                                  rx_submit_list) {
 615                 spin_unlock_irqrestore(&rx->submit_list_lock, flags);
 616                 usb_kill_urb(r->urb);
 617                 spin_lock_irqsave(&rx->submit_list_lock, flags);
 618         }
 619         spin_unlock_irqrestore(&rx->submit_list_lock, flags);
 620
 621         return 0;
 622 }
 623
 624 static int gdm_mux_resume(struct usb_interface *intf)
 625 {
 626         struct tty_dev *tty_dev;
 627         struct mux_dev *mux_dev;
 628         u8 i;
 629
 630         tty_dev = usb_get_intfdata(intf);
 631         mux_dev = tty_dev->priv_dev;
 632
 633         if (mux_dev->usb_state != PM_SUSPEND) {
 634                 dev_err(intf->usb_dev, "usb resume - invalid state\n");
 635                 return -1;
 636         }
 637
 638         mux_dev->usb_state = PM_NORMAL;
 639
 640         for (i = 0; i < MAX_ISSUE_NUM; i++)
 641                 gdm_mux_recv(mux_dev, mux_dev->rx_cb);
 642
 643         return 0;
 644 }
 645
 646 static struct usb_driver gdm_mux_driver = {
 647         .name = "gdm_mux",
 648         .probe = gdm_mux_probe,
 649         .disconnect = gdm_mux_disconnect,
 650         .id_table = id_table,
 651         .supports_autosuspend = 1,
 652         .suspend = gdm_mux_suspend,
 653         .resume = gdm_mux_resume,
 654         .reset_resume = gdm_mux_resume,
 655 };
 656
 657 static int __init gdm_usb_mux_init(void)
 658 {
 659
 660         mux_rx_wq = create_workqueue("mux_rx_wq");
 661         if (!mux_rx_wq) {
 662                 pr_err("work queue create fail\n");
 663                 return -1;
 664         }
 665
 666         register_lte_tty_driver();
 667
 668         return usb_register(&gdm_mux_driver);
 669 }
 670
 671 static void __exit gdm_usb_mux_exit(void)
 672 {
 673         unregister_lte_tty_driver();
 674
 675         if (mux_rx_wq) {
 676                 flush_workqueue(mux_rx_wq);
 677                 destroy_workqueue(mux_rx_wq);
 678         }
 679
 680         usb_deregister(&gdm_mux_driver);
 681 }
 682
 683 module_init(gdm_usb_mux_init);
 684 module_exit(gdm_usb_mux_exit);
 685
 686 MODULE_DESCRIPTION("GCT LTE TTY Device Driver");
 687 MODULE_LICENSE("GPL");