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 ssize_t dbc_tty_write(struct tty_struct *tty, const u8 *buf,
 212                              size_t count)
 213 {
 214         struct dbc_port         *port = tty->driver_data;
 215         unsigned long           flags;
 216
 217         spin_lock_irqsave(&port->port_lock, flags);
 218         if (count)
 219                 count = kfifo_in(&port->write_fifo, buf, count);
 220         dbc_start_tx(port);
 221         spin_unlock_irqrestore(&port->port_lock, flags);
 222
 223         return count;
 224 }
 225
 226 static int dbc_tty_put_char(struct tty_struct *tty, u8 ch)
 227 {
 228         struct dbc_port         *port = tty->driver_data;
 229         unsigned long           flags;
 230         int                     status;
 231
 232         spin_lock_irqsave(&port->port_lock, flags);
 233         status = kfifo_put(&port->write_fifo, ch);
 234         spin_unlock_irqrestore(&port->port_lock, flags);
 235
 236         return status;
 237 }
 238
 239 static void dbc_tty_flush_chars(struct tty_struct *tty)
 240 {
 241         struct dbc_port         *port = tty->driver_data;
 242         unsigned long           flags;
 243
 244         spin_lock_irqsave(&port->port_lock, flags);
 245         dbc_start_tx(port);
 246         spin_unlock_irqrestore(&port->port_lock, flags);
 247 }
 248
 249 static unsigned int dbc_tty_write_room(struct tty_struct *tty)
 250 {
 251         struct dbc_port         *port = tty->driver_data;
 252         unsigned long           flags;
 253         unsigned int            room;
 254
 255         spin_lock_irqsave(&port->port_lock, flags);
 256         room = kfifo_avail(&port->write_fifo);
 257         spin_unlock_irqrestore(&port->port_lock, flags);
 258
 259         return room;
 260 }
 261
 262 static unsigned int dbc_tty_chars_in_buffer(struct tty_struct *tty)
 263 {
 264         struct dbc_port         *port = tty->driver_data;
 265         unsigned long           flags;
 266         unsigned int            chars;
 267
 268         spin_lock_irqsave(&port->port_lock, flags);
 269         chars = kfifo_len(&port->write_fifo);
 270         spin_unlock_irqrestore(&port->port_lock, flags);
 271
 272         return chars;
 273 }
 274
 275 static void dbc_tty_unthrottle(struct tty_struct *tty)
 276 {
 277         struct dbc_port         *port = tty->driver_data;
 278         unsigned long           flags;
 279
 280         spin_lock_irqsave(&port->port_lock, flags);
 281         tasklet_schedule(&port->push);
 282         spin_unlock_irqrestore(&port->port_lock, flags);
 283 }
 284
 285 static const struct tty_operations dbc_tty_ops = {
 286         .install                = dbc_tty_install,
 287         .open                   = dbc_tty_open,
 288         .close                  = dbc_tty_close,
 289         .write                  = dbc_tty_write,
 290         .put_char               = dbc_tty_put_char,
 291         .flush_chars            = dbc_tty_flush_chars,
 292         .write_room             = dbc_tty_write_room,
 293         .chars_in_buffer        = dbc_tty_chars_in_buffer,
 294         .unthrottle             = dbc_tty_unthrottle,
 295 };
 296
 297 static void dbc_rx_push(struct tasklet_struct *t)
 298 {
 299         struct dbc_request      *req;
 300         struct tty_struct       *tty;
 301         unsigned long           flags;
 302         bool                    do_push = false;
 303         bool                    disconnect = false;
 304         struct dbc_port         *port = from_tasklet(port, t, push);
 305         struct list_head        *queue = &port->read_queue;
 306
 307         spin_lock_irqsave(&port->port_lock, flags);
 308         tty = port->port.tty;
 309         while (!list_empty(queue)) {
 310                 req = list_first_entry(queue, struct dbc_request, list_pool);
 311
 312                 if (tty && tty_throttled(tty))
 313                         break;
 314
 315                 switch (req->status) {
 316                 case 0:
 317                         break;
 318                 case -ESHUTDOWN:
 319                         disconnect = true;
 320                         break;
 321                 default:
 322                         pr_warn("ttyDBC0: unexpected RX status %d\n",
 323                                 req->status);
 324                         break;
 325                 }
 326
 327                 if (req->actual) {
 328                         char            *packet = req->buf;
 329                         unsigned int    n, size = req->actual;
 330                         int             count;
 331
 332                         n = port->n_read;
 333                         if (n) {
 334                                 packet += n;
 335                                 size -= n;
 336                         }
 337
 338                         count = tty_insert_flip_string(&port->port, packet,
 339                                                        size);
 340                         if (count)
 341                                 do_push = true;
 342                         if (count != size) {
 343                                 port->n_read += count;
 344                                 break;
 345                         }
 346                         port->n_read = 0;
 347                 }
 348
 349                 list_move(&req->list_pool, &port->read_pool);
 350         }
 351
 352         if (do_push)
 353                 tty_flip_buffer_push(&port->port);
 354
 355         if (!list_empty(queue) && tty) {
 356                 if (!tty_throttled(tty)) {
 357                         if (do_push)
 358                                 tasklet_schedule(&port->push);
 359                         else
 360                                 pr_warn("ttyDBC0: RX not scheduled?\n");
 361                 }
 362         }
 363
 364         if (!disconnect)
 365                 dbc_start_rx(port);
 366
 367         spin_unlock_irqrestore(&port->port_lock, flags);
 368 }
 369
 370 static int dbc_port_activate(struct tty_port *_port, struct tty_struct *tty)
 371 {
 372         unsigned long   flags;
 373         struct dbc_port *port = container_of(_port, struct dbc_port, port);
 374
 375         spin_lock_irqsave(&port->port_lock, flags);
 376         dbc_start_rx(port);
 377         spin_unlock_irqrestore(&port->port_lock, flags);
 378
 379         return 0;
 380 }
 381
 382 static const struct tty_port_operations dbc_port_ops = {
 383         .activate =     dbc_port_activate,
 384 };
 385
 386 static void
 387 xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port)
 388 {
 389         tty_port_init(&port->port);
 390         spin_lock_init(&port->port_lock);
 391         tasklet_setup(&port->push, dbc_rx_push);
 392         INIT_LIST_HEAD(&port->read_pool);
 393         INIT_LIST_HEAD(&port->read_queue);
 394         INIT_LIST_HEAD(&port->write_pool);
 395
 396         port->port.ops =        &dbc_port_ops;
 397         port->n_read =          0;
 398 }
 399
 400 static void
 401 xhci_dbc_tty_exit_port(struct dbc_port *port)
 402 {
 403         tasklet_kill(&port->push);
 404         tty_port_destroy(&port->port);
 405 }
 406
 407 static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
 408 {
 409         int                     ret;
 410         struct device           *tty_dev;
 411         struct dbc_port         *port = dbc_to_port(dbc);
 412
 413         if (port->registered)
 414                 return -EBUSY;
 415
 416         xhci_dbc_tty_init_port(dbc, port);
 417
 418         mutex_lock(&dbc_tty_minors_lock);
 419         port->minor = idr_alloc(&dbc_tty_minors, port, 0, 64, GFP_KERNEL);
 420         mutex_unlock(&dbc_tty_minors_lock);
 421
 422         if (port->minor < 0) {
 423                 ret = port->minor;
 424                 goto err_idr;
 425         }
 426
 427         ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
 428         if (ret)
 429                 goto err_exit_port;
 430
 431         ret = xhci_dbc_alloc_requests(dbc, BULK_IN, &port->read_pool,
 432                                       dbc_read_complete);
 433         if (ret)
 434                 goto err_free_fifo;
 435
 436         ret = xhci_dbc_alloc_requests(dbc, BULK_OUT, &port->write_pool,
 437                                       dbc_write_complete);
 438         if (ret)
 439                 goto err_free_requests;
 440
 441         tty_dev = tty_port_register_device(&port->port,
 442                                            dbc_tty_driver, port->minor, NULL);
 443         if (IS_ERR(tty_dev)) {
 444                 ret = PTR_ERR(tty_dev);
 445                 goto err_free_requests;
 446         }
 447
 448         port->registered = true;
 449
 450         return 0;
 451
 452 err_free_requests:
 453         xhci_dbc_free_requests(&port->read_pool);
 454         xhci_dbc_free_requests(&port->write_pool);
 455 err_free_fifo:
 456         kfifo_free(&port->write_fifo);
 457 err_exit_port:
 458         idr_remove(&dbc_tty_minors, port->minor);
 459 err_idr:
 460         xhci_dbc_tty_exit_port(port);
 461
 462         dev_err(dbc->dev, "can't register tty port, err %d\n", ret);
 463
 464         return ret;
 465 }
 466
 467 static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
 468 {
 469         struct dbc_port         *port = dbc_to_port(dbc);
 470
 471         if (!port->registered)
 472                 return;
 473         tty_unregister_device(dbc_tty_driver, port->minor);
 474         xhci_dbc_tty_exit_port(port);
 475         port->registered = false;
 476
 477         mutex_lock(&dbc_tty_minors_lock);
 478         idr_remove(&dbc_tty_minors, port->minor);
 479         mutex_unlock(&dbc_tty_minors_lock);
 480
 481         kfifo_free(&port->write_fifo);
 482         xhci_dbc_free_requests(&port->read_pool);
 483         xhci_dbc_free_requests(&port->read_queue);
 484         xhci_dbc_free_requests(&port->write_pool);
 485 }
 486
 487 static const struct dbc_driver dbc_driver = {
 488         .configure              = xhci_dbc_tty_register_device,
 489         .disconnect             = xhci_dbc_tty_unregister_device,
 490 };
 491
 492 int xhci_dbc_tty_probe(struct device *dev, void __iomem *base, struct xhci_hcd *xhci)
 493 {
 494         struct xhci_dbc         *dbc;
 495         struct dbc_port         *port;
 496         int                     status;
 497
 498         if (!dbc_tty_driver)
 499                 return -ENODEV;
 500
 501         port = kzalloc(sizeof(*port), GFP_KERNEL);
 502         if (!port)
 503                 return -ENOMEM;
 504
 505         dbc = xhci_alloc_dbc(dev, base, &dbc_driver);
 506
 507         if (!dbc) {
 508                 status = -ENOMEM;
 509                 goto out2;
 510         }
 511
 512         dbc->priv = port;
 513
 514         /* get rid of xhci once this is a real driver binding to a device */
 515         xhci->dbc = dbc;
 516
 517         return 0;
 518 out2:
 519         kfree(port);
 520
 521         return status;
 522 }
 523
 524 /*
 525  * undo what probe did, assume dbc is stopped already.
 526  * we also assume tty_unregister_device() is called before this
 527  */
 528 void xhci_dbc_tty_remove(struct xhci_dbc *dbc)
 529 {
 530         struct dbc_port         *port = dbc_to_port(dbc);
 531
 532         xhci_dbc_remove(dbc);
 533         kfree(port);
 534 }
 535
 536 int dbc_tty_init(void)
 537 {
 538         int             ret;
 539
 540         idr_init(&dbc_tty_minors);
 541
 542         dbc_tty_driver = tty_alloc_driver(64, TTY_DRIVER_REAL_RAW |
 543                                           TTY_DRIVER_DYNAMIC_DEV);
 544         if (IS_ERR(dbc_tty_driver)) {
 545                 idr_destroy(&dbc_tty_minors);
 546                 return PTR_ERR(dbc_tty_driver);
 547         }
 548
 549         dbc_tty_driver->driver_name = "dbc_serial";
 550         dbc_tty_driver->name = "ttyDBC";
 551
 552         dbc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 553         dbc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
 554         dbc_tty_driver->init_termios = tty_std_termios;
 555         dbc_tty_driver->init_termios.c_cflag =
 556                         B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 557         dbc_tty_driver->init_termios.c_ispeed = 9600;
 558         dbc_tty_driver->init_termios.c_ospeed = 9600;
 559
 560         tty_set_operations(dbc_tty_driver, &dbc_tty_ops);
 561
 562         ret = tty_register_driver(dbc_tty_driver);
 563         if (ret) {
 564                 pr_err("Can't register dbc tty driver\n");
 565                 tty_driver_kref_put(dbc_tty_driver);
 566                 idr_destroy(&dbc_tty_minors);
 567         }
 568
 569         return ret;
 570 }
 571
 572 void dbc_tty_exit(void)
 573 {
 574         if (dbc_tty_driver) {
 575                 tty_unregister_driver(dbc_tty_driver);
 576                 tty_driver_kref_put(dbc_tty_driver);
 577                 dbc_tty_driver = NULL;
 578         }
 579
 580         idr_destroy(&dbc_tty_minors);
 581 }