drivers/usb/host/xhci-dbgtty.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * xhci-dbgtty.c - tty glue for xHCI debug capability
   4  *
   5  * Copyright (C) 2017 Intel Corporation
   6  *
   7  * Author: Lu Baolu <baolu.lu@linux.intel.com>
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/tty.h>
  12 #include <linux/tty_flip.h>
  13 #include <linux/idr.h>
  14
  15 #include "xhci.h"
  16 #include "xhci-dbgcap.h"
  17
  18 static struct tty_driver *dbc_tty_driver;
  19 static struct idr dbc_tty_minors;
  20 static DEFINE_MUTEX(dbc_tty_minors_lock);
  21
  22 static inline struct dbc_port *dbc_to_port(struct xhci_dbc *dbc)
  23 {
  24         return dbc->priv;
  25 }
  26
  27 static unsigned int
  28 dbc_send_packet(struct dbc_port *port, char *packet, unsigned int size)
  29 {
  30         unsigned int            len;
  31
  32         len = kfifo_len(&port->write_fifo);
  33         if (len < size)
  34                 size = len;
  35         if (size != 0)
  36                 size = kfifo_out(&port->write_fifo, packet, size);
  37         return size;
  38 }
  39
  40 static int dbc_start_tx(struct dbc_port *port)
  41         __releases(&port->port_lock)
  42         __acquires(&port->port_lock)
  43 {
  44         int                     len;
  45         struct dbc_request      *req;
  46         int                     status = 0;
  47         bool                    do_tty_wake = false;
  48         struct list_head        *pool = &port->write_pool;
  49
  50         while (!list_empty(pool)) {
  51                 req = list_entry(pool->next, struct dbc_request, list_pool);
  52                 len = dbc_send_packet(port, req->buf, DBC_MAX_PACKET);
  53                 if (len == 0)
  54                         break;
  55                 do_tty_wake = true;
  56
  57                 req->length = len;
  58                 list_del(&req->list_pool);
  59
  60                 spin_unlock(&port->port_lock);
  61                 status = dbc_ep_queue(req);
  62                 spin_lock(&port->port_lock);
  63
  64                 if (status) {
  65                         list_add(&req->list_pool, pool);
  66                         break;
  67                 }
  68         }
  69
  70         if (do_tty_wake && port->port.tty)
  71                 tty_wakeup(port->port.tty);
  72
  73         return status;
  74 }
  75
  76 static void dbc_start_rx(struct dbc_port *port)
  77         __releases(&port->port_lock)
  78         __acquires(&port->port_lock)
  79 {
  80         struct dbc_request      *req;
  81         int                     status;
  82         struct list_head        *pool = &port->read_pool;
  83
  84         while (!list_empty(pool)) {
  85                 if (!port->port.tty)
  86                         break;
  87
  88                 req = list_entry(pool->next, struct dbc_request, list_pool);
  89                 list_del(&req->list_pool);
  90                 req->length = DBC_MAX_PACKET;
  91
  92                 spin_unlock(&port->port_lock);
  93                 status = dbc_ep_queue(req);
  94                 spin_lock(&port->port_lock);
  95
  96                 if (status) {
  97                         list_add(&req->list_pool, pool);
  98                         break;
  99                 }
 100         }
 101 }
 102
 103 static void
 104 dbc_read_complete(struct xhci_dbc *dbc, struct dbc_request *req)
 105 {
 106         unsigned long           flags;
 107         struct dbc_port         *port = dbc_to_port(dbc);
 108
 109         spin_lock_irqsave(&port->port_lock, flags);
 110         list_add_tail(&req->list_pool, &port->read_queue);
 111         tasklet_schedule(&port->push);
 112         spin_unlock_irqrestore(&port->port_lock, flags);
 113 }
 114
 115 static void dbc_write_complete(struct xhci_dbc *dbc, struct dbc_request *req)
 116 {
 117         unsigned long           flags;
 118         struct dbc_port         *port = dbc_to_port(dbc);
 119
 120         spin_lock_irqsave(&port->port_lock, flags);
 121         list_add(&req->list_pool, &port->write_pool);
 122         switch (req->status) {
 123         case 0:
 124                 dbc_start_tx(port);
 125                 break;
 126         case -ESHUTDOWN:
 127                 break;
 128         default:
 129                 dev_warn(dbc->dev, "unexpected write complete status %d\n",
 130                           req->status);
 131                 break;
 132         }
 133         spin_unlock_irqrestore(&port->port_lock, flags);
 134 }
 135
 136 static void xhci_dbc_free_req(struct dbc_request *req)
 137 {
 138         kfree(req->buf);
 139         dbc_free_request(req);
 140 }
 141
 142 static int
 143 xhci_dbc_alloc_requests(struct xhci_dbc *dbc, unsigned int direction,
 144                         struct list_head *head,
 145                         void (*fn)(struct xhci_dbc *, struct dbc_request *))
 146 {
 147         int                     i;
 148         struct dbc_request      *req;
 149
 150         for (i = 0; i < DBC_QUEUE_SIZE; i++) {
 151                 req = dbc_alloc_request(dbc, direction, GFP_KERNEL);
 152                 if (!req)
 153                         break;
 154
 155                 req->length = DBC_MAX_PACKET;
 156                 req->buf = kmalloc(req->length, GFP_KERNEL);
 157                 if (!req->buf) {
 158                         dbc_free_request(req);
 159                         break;
 160                 }
 161
 162                 req->complete = fn;
 163                 list_add_tail(&req->list_pool, head);
 164         }
 165
 166         return list_empty(head) ? -ENOMEM : 0;
 167 }
 168
 169 static void
 170 xhci_dbc_free_requests(struct list_head *head)
 171 {
 172         struct dbc_request      *req;
 173
 174         while (!list_empty(head)) {
 175                 req = list_entry(head->next, struct dbc_request, list_pool);
 176                 list_del(&req->list_pool);
 177                 xhci_dbc_free_req(req);
 178         }
 179 }
 180
 181 static int dbc_tty_install(struct tty_driver *driver, struct tty_struct *tty)
 182 {
 183         struct dbc_port         *port;
 184
 185         mutex_lock(&dbc_tty_minors_lock);
 186         port = idr_find(&dbc_tty_minors, tty->index);
 187         mutex_unlock(&dbc_tty_minors_lock);
 188
 189         if (!port)
 190                 return -ENXIO;
 191
 192         tty->driver_data = port;
 193
 194         return tty_port_install(&port->port, driver, tty);
 195 }
 196
 197 static int dbc_tty_open(struct tty_struct *tty, struct file *file)
 198 {
 199         struct dbc_port         *port = tty->driver_data;
 200
 201         return tty_port_open(&port->port, tty, file);
 202 }
 203
 204 static void dbc_tty_close(struct tty_struct *tty, struct file *file)
 205 {
 206         struct dbc_port         *port = tty->driver_data;
 207
 208         tty_port_close(&port->port, tty, file);
 209 }
 210
 211 static int dbc_tty_write(struct tty_struct *tty,
 212                          const unsigned char *buf,
 213                          int count)
 214 {
 215         struct dbc_port         *port = tty->driver_data;
 216         unsigned long           flags;
 217
 218         spin_lock_irqsave(&port->port_lock, flags);
 219         if (count)
 220                 count = kfifo_in(&port->write_fifo, buf, count);
 221         dbc_start_tx(port);
 222         spin_unlock_irqrestore(&port->port_lock, flags);
 223
 224         return count;
 225 }
 226
 227 static int dbc_tty_put_char(struct tty_struct *tty, unsigned char ch)
 228 {
 229         struct dbc_port         *port = tty->driver_data;
 230         unsigned long           flags;
 231         int                     status;
 232
 233         spin_lock_irqsave(&port->port_lock, flags);
 234         status = kfifo_put(&port->write_fifo, ch);
 235         spin_unlock_irqrestore(&port->port_lock, flags);
 236
 237         return status;
 238 }
 239
 240 static void dbc_tty_flush_chars(struct tty_struct *tty)
 241 {
 242         struct dbc_port         *port = tty->driver_data;
 243         unsigned long           flags;
 244
 245         spin_lock_irqsave(&port->port_lock, flags);
 246         dbc_start_tx(port);
 247         spin_unlock_irqrestore(&port->port_lock, flags);
 248 }
 249
 250 static unsigned int dbc_tty_write_room(struct tty_struct *tty)
 251 {
 252         struct dbc_port         *port = tty->driver_data;
 253         unsigned long           flags;
 254         unsigned int            room;
 255
 256         spin_lock_irqsave(&port->port_lock, flags);
 257         room = kfifo_avail(&port->write_fifo);
 258         spin_unlock_irqrestore(&port->port_lock, flags);
 259
 260         return room;
 261 }
 262
 263 static unsigned int dbc_tty_chars_in_buffer(struct tty_struct *tty)
 264 {
 265         struct dbc_port         *port = tty->driver_data;
 266         unsigned long           flags;
 267         unsigned int            chars;
 268
 269         spin_lock_irqsave(&port->port_lock, flags);
 270         chars = kfifo_len(&port->write_fifo);
 271         spin_unlock_irqrestore(&port->port_lock, flags);
 272
 273         return chars;
 274 }
 275
 276 static void dbc_tty_unthrottle(struct tty_struct *tty)
 277 {
 278         struct dbc_port         *port = tty->driver_data;
 279         unsigned long           flags;
 280
 281         spin_lock_irqsave(&port->port_lock, flags);
 282         tasklet_schedule(&port->push);
 283         spin_unlock_irqrestore(&port->port_lock, flags);
 284 }
 285
 286 static const struct tty_operations dbc_tty_ops = {
 287         .install                = dbc_tty_install,
 288         .open                   = dbc_tty_open,
 289         .close                  = dbc_tty_close,
 290         .write                  = dbc_tty_write,
 291         .put_char               = dbc_tty_put_char,
 292         .flush_chars            = dbc_tty_flush_chars,
 293         .write_room             = dbc_tty_write_room,
 294         .chars_in_buffer        = dbc_tty_chars_in_buffer,
 295         .unthrottle             = dbc_tty_unthrottle,
 296 };
 297
 298 static void dbc_rx_push(struct tasklet_struct *t)
 299 {
 300         struct dbc_request      *req;
 301         struct tty_struct       *tty;
 302         unsigned long           flags;
 303         bool                    do_push = false;
 304         bool                    disconnect = false;
 305         struct dbc_port         *port = from_tasklet(port, t, push);
 306         struct list_head        *queue = &port->read_queue;
 307
 308         spin_lock_irqsave(&port->port_lock, flags);
 309         tty = port->port.tty;
 310         while (!list_empty(queue)) {
 311                 req = list_first_entry(queue, struct dbc_request, list_pool);
 312
 313                 if (tty && tty_throttled(tty))
 314                         break;
 315
 316                 switch (req->status) {
 317                 case 0:
 318                         break;
 319                 case -ESHUTDOWN:
 320                         disconnect = true;
 321                         break;
 322                 default:
 323                         pr_warn("ttyDBC0: unexpected RX status %d\n",
 324                                 req->status);
 325                         break;
 326                 }
 327
 328                 if (req->actual) {
 329                         char            *packet = req->buf;
 330                         unsigned int    n, size = req->actual;
 331                         int             count;
 332
 333                         n = port->n_read;
 334                         if (n) {
 335                                 packet += n;
 336                                 size -= n;
 337                         }
 338
 339                         count = tty_insert_flip_string(&port->port, packet,
 340                                                        size);
 341                         if (count)
 342                                 do_push = true;
 343                         if (count != size) {
 344                                 port->n_read += count;
 345                                 break;
 346                         }
 347                         port->n_read = 0;
 348                 }
 349
 350                 list_move(&req->list_pool, &port->read_pool);
 351         }
 352
 353         if (do_push)
 354                 tty_flip_buffer_push(&port->port);
 355
 356         if (!list_empty(queue) && tty) {
 357                 if (!tty_throttled(tty)) {
 358                         if (do_push)
 359                                 tasklet_schedule(&port->push);
 360                         else
 361                                 pr_warn("ttyDBC0: RX not scheduled?\n");
 362                 }
 363         }
 364
 365         if (!disconnect)
 366                 dbc_start_rx(port);
 367
 368         spin_unlock_irqrestore(&port->port_lock, flags);
 369 }
 370
 371 static int dbc_port_activate(struct tty_port *_port, struct tty_struct *tty)
 372 {
 373         unsigned long   flags;
 374         struct dbc_port *port = container_of(_port, struct dbc_port, port);
 375
 376         spin_lock_irqsave(&port->port_lock, flags);
 377         dbc_start_rx(port);
 378         spin_unlock_irqrestore(&port->port_lock, flags);
 379
 380         return 0;
 381 }
 382
 383 static const struct tty_port_operations dbc_port_ops = {
 384         .activate =     dbc_port_activate,
 385 };
 386
 387 static void
 388 xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port)
 389 {
 390         tty_port_init(&port->port);
 391         spin_lock_init(&port->port_lock);
 392         tasklet_setup(&port->push, dbc_rx_push);
 393         INIT_LIST_HEAD(&port->read_pool);
 394         INIT_LIST_HEAD(&port->read_queue);
 395         INIT_LIST_HEAD(&port->write_pool);
 396
 397         port->port.ops =        &dbc_port_ops;
 398         port->n_read =          0;
 399 }
 400
 401 static void
 402 xhci_dbc_tty_exit_port(struct dbc_port *port)
 403 {
 404         tasklet_kill(&port->push);
 405         tty_port_destroy(&port->port);
 406 }
 407
 408 static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
 409 {
 410         int                     ret;
 411         struct device           *tty_dev;
 412         struct dbc_port         *port = dbc_to_port(dbc);
 413
 414         if (port->registered)
 415                 return -EBUSY;
 416
 417         xhci_dbc_tty_init_port(dbc, port);
 418
 419         mutex_lock(&dbc_tty_minors_lock);
 420         port->minor = idr_alloc(&dbc_tty_minors, port, 0, 64, GFP_KERNEL);
 421         mutex_unlock(&dbc_tty_minors_lock);
 422
 423         if (port->minor < 0) {
 424                 ret = port->minor;
 425                 goto err_idr;
 426         }
 427
 428         ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
 429         if (ret)
 430                 goto err_exit_port;
 431
 432         ret = xhci_dbc_alloc_requests(dbc, BULK_IN, &port->read_pool,
 433                                       dbc_read_complete);
 434         if (ret)
 435                 goto err_free_fifo;
 436
 437         ret = xhci_dbc_alloc_requests(dbc, BULK_OUT, &port->write_pool,
 438                                       dbc_write_complete);
 439         if (ret)
 440                 goto err_free_requests;
 441
 442         tty_dev = tty_port_register_device(&port->port,
 443                                            dbc_tty_driver, port->minor, NULL);
 444         if (IS_ERR(tty_dev)) {
 445                 ret = PTR_ERR(tty_dev);
 446                 goto err_free_requests;
 447         }
 448
 449         port->registered = true;
 450
 451         return 0;
 452
 453 err_free_requests:
 454         xhci_dbc_free_requests(&port->read_pool);
 455         xhci_dbc_free_requests(&port->write_pool);
 456 err_free_fifo:
 457         kfifo_free(&port->write_fifo);
 458 err_exit_port:
 459         idr_remove(&dbc_tty_minors, port->minor);
 460 err_idr:
 461         xhci_dbc_tty_exit_port(port);
 462
 463         dev_err(dbc->dev, "can't register tty port, err %d\n", ret);
 464
 465         return ret;
 466 }
 467
 468 static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
 469 {
 470         struct dbc_port         *port = dbc_to_port(dbc);
 471
 472         if (!port->registered)
 473                 return;
 474         tty_unregister_device(dbc_tty_driver, port->minor);
 475         xhci_dbc_tty_exit_port(port);
 476         port->registered = false;
 477
 478         mutex_lock(&dbc_tty_minors_lock);
 479         idr_remove(&dbc_tty_minors, port->minor);
 480         mutex_unlock(&dbc_tty_minors_lock);
 481
 482         kfifo_free(&port->write_fifo);
 483         xhci_dbc_free_requests(&port->read_pool);
 484         xhci_dbc_free_requests(&port->read_queue);
 485         xhci_dbc_free_requests(&port->write_pool);
 486 }
 487
 488 static const struct dbc_driver dbc_driver = {
 489         .configure              = xhci_dbc_tty_register_device,
 490         .disconnect             = xhci_dbc_tty_unregister_device,
 491 };
 492
 493 int xhci_dbc_tty_probe(struct device *dev, void __iomem *base, struct xhci_hcd *xhci)
 494 {
 495         struct xhci_dbc         *dbc;
 496         struct dbc_port         *port;
 497         int                     status;
 498
 499         if (!dbc_tty_driver)
 500                 return -ENODEV;
 501
 502         port = kzalloc(sizeof(*port), GFP_KERNEL);
 503         if (!port)
 504                 return -ENOMEM;
 505
 506         dbc = xhci_alloc_dbc(dev, base, &dbc_driver);
 507
 508         if (!dbc) {
 509                 status = -ENOMEM;
 510                 goto out2;
 511         }
 512
 513         dbc->priv = port;
 514
 515         /* get rid of xhci once this is a real driver binding to a device */
 516         xhci->dbc = dbc;
 517
 518         return 0;
 519 out2:
 520         kfree(port);
 521
 522         return status;
 523 }
 524
 525 /*
 526  * undo what probe did, assume dbc is stopped already.
 527  * we also assume tty_unregister_device() is called before this
 528  */
 529 void xhci_dbc_tty_remove(struct xhci_dbc *dbc)
 530 {
 531         struct dbc_port         *port = dbc_to_port(dbc);
 532
 533         xhci_dbc_remove(dbc);
 534         kfree(port);
 535 }
 536
 537 int dbc_tty_init(void)
 538 {
 539         int             ret;
 540
 541         idr_init(&dbc_tty_minors);
 542
 543         dbc_tty_driver = tty_alloc_driver(64, TTY_DRIVER_REAL_RAW |
 544                                           TTY_DRIVER_DYNAMIC_DEV);
 545         if (IS_ERR(dbc_tty_driver)) {
 546                 idr_destroy(&dbc_tty_minors);
 547                 return PTR_ERR(dbc_tty_driver);
 548         }
 549
 550         dbc_tty_driver->driver_name = "dbc_serial";
 551         dbc_tty_driver->name = "ttyDBC";
 552
 553         dbc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 554         dbc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
 555         dbc_tty_driver->init_termios = tty_std_termios;
 556         dbc_tty_driver->init_termios.c_cflag =
 557                         B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 558         dbc_tty_driver->init_termios.c_ispeed = 9600;
 559         dbc_tty_driver->init_termios.c_ospeed = 9600;
 560
 561         tty_set_operations(dbc_tty_driver, &dbc_tty_ops);
 562
 563         ret = tty_register_driver(dbc_tty_driver);
 564         if (ret) {
 565                 pr_err("Can't register dbc tty driver\n");
 566                 tty_driver_kref_put(dbc_tty_driver);
 567                 idr_destroy(&dbc_tty_minors);
 568         }
 569
 570         return ret;
 571 }
 572
 573 void dbc_tty_exit(void)
 574 {
 575         if (dbc_tty_driver) {
 576                 tty_unregister_driver(dbc_tty_driver);
 577                 tty_driver_kref_put(dbc_tty_driver);
 578                 dbc_tty_driver = NULL;
 579         }
 580
 581         idr_destroy(&dbc_tty_minors);
 582 }