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
  14 #include "xhci.h"
  15 #include "xhci-dbgcap.h"
  16
  17 static int dbc_tty_init(void);
  18 static void dbc_tty_exit(void);
  19
  20 static struct tty_driver *dbc_tty_driver;
  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 = driver->driver_state;
 184
 185         tty->driver_data = port;
 186
 187         return tty_port_install(&port->port, driver, tty);
 188 }
 189
 190 static int dbc_tty_open(struct tty_struct *tty, struct file *file)
 191 {
 192         struct dbc_port         *port = tty->driver_data;
 193
 194         return tty_port_open(&port->port, tty, file);
 195 }
 196
 197 static void dbc_tty_close(struct tty_struct *tty, struct file *file)
 198 {
 199         struct dbc_port         *port = tty->driver_data;
 200
 201         tty_port_close(&port->port, tty, file);
 202 }
 203
 204 static int dbc_tty_write(struct tty_struct *tty,
 205                          const unsigned char *buf,
 206                          int count)
 207 {
 208         struct dbc_port         *port = tty->driver_data;
 209         unsigned long           flags;
 210
 211         spin_lock_irqsave(&port->port_lock, flags);
 212         if (count)
 213                 count = kfifo_in(&port->write_fifo, buf, count);
 214         dbc_start_tx(port);
 215         spin_unlock_irqrestore(&port->port_lock, flags);
 216
 217         return count;
 218 }
 219
 220 static int dbc_tty_put_char(struct tty_struct *tty, unsigned char ch)
 221 {
 222         struct dbc_port         *port = tty->driver_data;
 223         unsigned long           flags;
 224         int                     status;
 225
 226         spin_lock_irqsave(&port->port_lock, flags);
 227         status = kfifo_put(&port->write_fifo, ch);
 228         spin_unlock_irqrestore(&port->port_lock, flags);
 229
 230         return status;
 231 }
 232
 233 static void dbc_tty_flush_chars(struct tty_struct *tty)
 234 {
 235         struct dbc_port         *port = tty->driver_data;
 236         unsigned long           flags;
 237
 238         spin_lock_irqsave(&port->port_lock, flags);
 239         dbc_start_tx(port);
 240         spin_unlock_irqrestore(&port->port_lock, flags);
 241 }
 242
 243 static unsigned int dbc_tty_write_room(struct tty_struct *tty)
 244 {
 245         struct dbc_port         *port = tty->driver_data;
 246         unsigned long           flags;
 247         unsigned int            room;
 248
 249         spin_lock_irqsave(&port->port_lock, flags);
 250         room = kfifo_avail(&port->write_fifo);
 251         spin_unlock_irqrestore(&port->port_lock, flags);
 252
 253         return room;
 254 }
 255
 256 static unsigned int dbc_tty_chars_in_buffer(struct tty_struct *tty)
 257 {
 258         struct dbc_port         *port = tty->driver_data;
 259         unsigned long           flags;
 260         unsigned int            chars;
 261
 262         spin_lock_irqsave(&port->port_lock, flags);
 263         chars = kfifo_len(&port->write_fifo);
 264         spin_unlock_irqrestore(&port->port_lock, flags);
 265
 266         return chars;
 267 }
 268
 269 static void dbc_tty_unthrottle(struct tty_struct *tty)
 270 {
 271         struct dbc_port         *port = tty->driver_data;
 272         unsigned long           flags;
 273
 274         spin_lock_irqsave(&port->port_lock, flags);
 275         tasklet_schedule(&port->push);
 276         spin_unlock_irqrestore(&port->port_lock, flags);
 277 }
 278
 279 static const struct tty_operations dbc_tty_ops = {
 280         .install                = dbc_tty_install,
 281         .open                   = dbc_tty_open,
 282         .close                  = dbc_tty_close,
 283         .write                  = dbc_tty_write,
 284         .put_char               = dbc_tty_put_char,
 285         .flush_chars            = dbc_tty_flush_chars,
 286         .write_room             = dbc_tty_write_room,
 287         .chars_in_buffer        = dbc_tty_chars_in_buffer,
 288         .unthrottle             = dbc_tty_unthrottle,
 289 };
 290
 291 static void dbc_rx_push(struct tasklet_struct *t)
 292 {
 293         struct dbc_request      *req;
 294         struct tty_struct       *tty;
 295         unsigned long           flags;
 296         bool                    do_push = false;
 297         bool                    disconnect = false;
 298         struct dbc_port         *port = from_tasklet(port, t, push);
 299         struct list_head        *queue = &port->read_queue;
 300
 301         spin_lock_irqsave(&port->port_lock, flags);
 302         tty = port->port.tty;
 303         while (!list_empty(queue)) {
 304                 req = list_first_entry(queue, struct dbc_request, list_pool);
 305
 306                 if (tty && tty_throttled(tty))
 307                         break;
 308
 309                 switch (req->status) {
 310                 case 0:
 311                         break;
 312                 case -ESHUTDOWN:
 313                         disconnect = true;
 314                         break;
 315                 default:
 316                         pr_warn("ttyDBC0: unexpected RX status %d\n",
 317                                 req->status);
 318                         break;
 319                 }
 320
 321                 if (req->actual) {
 322                         char            *packet = req->buf;
 323                         unsigned int    n, size = req->actual;
 324                         int             count;
 325
 326                         n = port->n_read;
 327                         if (n) {
 328                                 packet += n;
 329                                 size -= n;
 330                         }
 331
 332                         count = tty_insert_flip_string(&port->port, packet,
 333                                                        size);
 334                         if (count)
 335                                 do_push = true;
 336                         if (count != size) {
 337                                 port->n_read += count;
 338                                 break;
 339                         }
 340                         port->n_read = 0;
 341                 }
 342
 343                 list_move(&req->list_pool, &port->read_pool);
 344         }
 345
 346         if (do_push)
 347                 tty_flip_buffer_push(&port->port);
 348
 349         if (!list_empty(queue) && tty) {
 350                 if (!tty_throttled(tty)) {
 351                         if (do_push)
 352                                 tasklet_schedule(&port->push);
 353                         else
 354                                 pr_warn("ttyDBC0: RX not scheduled?\n");
 355                 }
 356         }
 357
 358         if (!disconnect)
 359                 dbc_start_rx(port);
 360
 361         spin_unlock_irqrestore(&port->port_lock, flags);
 362 }
 363
 364 static int dbc_port_activate(struct tty_port *_port, struct tty_struct *tty)
 365 {
 366         unsigned long   flags;
 367         struct dbc_port *port = container_of(_port, struct dbc_port, port);
 368
 369         spin_lock_irqsave(&port->port_lock, flags);
 370         dbc_start_rx(port);
 371         spin_unlock_irqrestore(&port->port_lock, flags);
 372
 373         return 0;
 374 }
 375
 376 static const struct tty_port_operations dbc_port_ops = {
 377         .activate =     dbc_port_activate,
 378 };
 379
 380 static void
 381 xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port)
 382 {
 383         tty_port_init(&port->port);
 384         spin_lock_init(&port->port_lock);
 385         tasklet_setup(&port->push, dbc_rx_push);
 386         INIT_LIST_HEAD(&port->read_pool);
 387         INIT_LIST_HEAD(&port->read_queue);
 388         INIT_LIST_HEAD(&port->write_pool);
 389
 390         port->port.ops =        &dbc_port_ops;
 391         port->n_read =          0;
 392 }
 393
 394 static void
 395 xhci_dbc_tty_exit_port(struct dbc_port *port)
 396 {
 397         tasklet_kill(&port->push);
 398         tty_port_destroy(&port->port);
 399 }
 400
 401 static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
 402 {
 403         int                     ret;
 404         struct device           *tty_dev;
 405         struct dbc_port         *port = dbc_to_port(dbc);
 406
 407         if (port->registered)
 408                 return -EBUSY;
 409
 410         xhci_dbc_tty_init_port(dbc, port);
 411
 412         ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
 413         if (ret)
 414                 goto err_exit_port;
 415
 416         ret = xhci_dbc_alloc_requests(dbc, BULK_IN, &port->read_pool,
 417                                       dbc_read_complete);
 418         if (ret)
 419                 goto err_free_fifo;
 420
 421         ret = xhci_dbc_alloc_requests(dbc, BULK_OUT, &port->write_pool,
 422                                       dbc_write_complete);
 423         if (ret)
 424                 goto err_free_requests;
 425
 426         tty_dev = tty_port_register_device(&port->port,
 427                                            dbc_tty_driver, 0, NULL);
 428         if (IS_ERR(tty_dev)) {
 429                 ret = PTR_ERR(tty_dev);
 430                 goto err_free_requests;
 431         }
 432
 433         port->registered = true;
 434
 435         return 0;
 436
 437 err_free_requests:
 438         xhci_dbc_free_requests(&port->read_pool);
 439         xhci_dbc_free_requests(&port->write_pool);
 440 err_free_fifo:
 441         kfifo_free(&port->write_fifo);
 442 err_exit_port:
 443         xhci_dbc_tty_exit_port(port);
 444
 445         dev_err(dbc->dev, "can't register tty port, err %d\n", ret);
 446
 447         return ret;
 448 }
 449
 450 static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
 451 {
 452         struct dbc_port         *port = dbc_to_port(dbc);
 453
 454         if (!port->registered)
 455                 return;
 456         tty_unregister_device(dbc_tty_driver, 0);
 457         xhci_dbc_tty_exit_port(port);
 458         port->registered = false;
 459
 460         kfifo_free(&port->write_fifo);
 461         xhci_dbc_free_requests(&port->read_pool);
 462         xhci_dbc_free_requests(&port->read_queue);
 463         xhci_dbc_free_requests(&port->write_pool);
 464 }
 465
 466 static const struct dbc_driver dbc_driver = {
 467         .configure              = xhci_dbc_tty_register_device,
 468         .disconnect             = xhci_dbc_tty_unregister_device,
 469 };
 470
 471 int xhci_dbc_tty_probe(struct xhci_hcd *xhci)
 472 {
 473         struct xhci_dbc         *dbc = xhci->dbc;
 474         struct dbc_port         *port;
 475         int                     status;
 476
 477         /* dbc_tty_init will be called by module init() in the future */
 478         status = dbc_tty_init();
 479         if (status)
 480                 return status;
 481
 482         port = kzalloc(sizeof(*port), GFP_KERNEL);
 483         if (!port) {
 484                 status = -ENOMEM;
 485                 goto out;
 486         }
 487
 488         dbc->driver = &dbc_driver;
 489         dbc->priv = port;
 490
 491
 492         dbc_tty_driver->driver_state = port;
 493
 494         return 0;
 495 out:
 496         /* dbc_tty_exit will be called by module_exit() in the future */
 497         dbc_tty_exit();
 498         return status;
 499 }
 500
 501 /*
 502  * undo what probe did, assume dbc is stopped already.
 503  * we also assume tty_unregister_device() is called before this
 504  */
 505 void xhci_dbc_tty_remove(struct xhci_dbc *dbc)
 506 {
 507         struct dbc_port         *port = dbc_to_port(dbc);
 508
 509         dbc->driver = NULL;
 510         dbc->priv = NULL;
 511         kfree(port);
 512
 513         /* dbc_tty_exit will be called by  module_exit() in the future */
 514         dbc_tty_exit();
 515 }
 516
 517 static int dbc_tty_init(void)
 518 {
 519         int             ret;
 520
 521         dbc_tty_driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW |
 522                                           TTY_DRIVER_DYNAMIC_DEV);
 523         if (IS_ERR(dbc_tty_driver))
 524                 return PTR_ERR(dbc_tty_driver);
 525
 526         dbc_tty_driver->driver_name = "dbc_serial";
 527         dbc_tty_driver->name = "ttyDBC";
 528
 529         dbc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 530         dbc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
 531         dbc_tty_driver->init_termios = tty_std_termios;
 532         dbc_tty_driver->init_termios.c_cflag =
 533                         B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 534         dbc_tty_driver->init_termios.c_ispeed = 9600;
 535         dbc_tty_driver->init_termios.c_ospeed = 9600;
 536
 537         tty_set_operations(dbc_tty_driver, &dbc_tty_ops);
 538
 539         ret = tty_register_driver(dbc_tty_driver);
 540         if (ret) {
 541                 pr_err("Can't register dbc tty driver\n");
 542                 tty_driver_kref_put(dbc_tty_driver);
 543         }
 544         return ret;
 545 }
 546
 547 static void dbc_tty_exit(void)
 548 {
 549         if (dbc_tty_driver) {
 550                 tty_unregister_driver(dbc_tty_driver);
 551                 tty_driver_kref_put(dbc_tty_driver);
 552                 dbc_tty_driver = NULL;
 553         }
 554 }