1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * USB Serial Converter Generic functions 4 * 5 * Copyright (C) 2010 - 2013 Johan Hovold (jhovold@gmail.com) 6 * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com) 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/sched/signal.h> 11 #include <linux/errno.h> 12 #include <linux/slab.h> 13 #include <linux/sysrq.h> 14 #include <linux/tty.h> 15 #include <linux/tty_flip.h> 16 #include <linux/module.h> 17 #include <linux/moduleparam.h> 18 #include <linux/usb.h> 19 #include <linux/usb/serial.h> 20 #include <linux/kfifo.h> 21 #include <linux/serial.h> 22 23 #ifdef CONFIG_USB_SERIAL_GENERIC 24 25 static __u16 vendor = 0x05f9; 26 static __u16 product = 0xffff; 27 28 module_param(vendor, ushort, 0); 29 MODULE_PARM_DESC(vendor, "User specified USB idVendor"); 30 31 module_param(product, ushort, 0); 32 MODULE_PARM_DESC(product, "User specified USB idProduct"); 33 34 static struct usb_device_id generic_device_ids[2]; /* Initially all zeroes. */ 35 36 static int usb_serial_generic_probe(struct usb_serial *serial, 37 const struct usb_device_id *id) 38 { 39 struct device *dev = &serial->interface->dev; 40 41 dev_info(dev, "The \"generic\" usb-serial driver is only for testing and one-off prototypes.\n"); 42 dev_info(dev, "Tell linux-usb@vger.kernel.org to add your device to a proper driver.\n"); 43 44 return 0; 45 } 46 47 static int usb_serial_generic_calc_num_ports(struct usb_serial *serial, 48 struct usb_serial_endpoints *epds) 49 { 50 struct device *dev = &serial->interface->dev; 51 int num_ports; 52 53 num_ports = max(epds->num_bulk_in, epds->num_bulk_out); 54 55 if (num_ports == 0) { 56 dev_err(dev, "device has no bulk endpoints\n"); 57 return -ENODEV; 58 } 59 60 return num_ports; 61 } 62 63 static struct usb_serial_driver usb_serial_generic_device = { 64 .driver = { 65 .name = "generic", 66 }, 67 .id_table = generic_device_ids, 68 .probe = usb_serial_generic_probe, 69 .calc_num_ports = usb_serial_generic_calc_num_ports, 70 .throttle = usb_serial_generic_throttle, 71 .unthrottle = usb_serial_generic_unthrottle, 72 .resume = usb_serial_generic_resume, 73 }; 74 75 static struct usb_serial_driver * const serial_drivers[] = { 76 &usb_serial_generic_device, NULL 77 }; 78 79 #endif 80 81 int usb_serial_generic_register(void) 82 { 83 int retval = 0; 84 85 #ifdef CONFIG_USB_SERIAL_GENERIC 86 generic_device_ids[0].idVendor = vendor; 87 generic_device_ids[0].idProduct = product; 88 generic_device_ids[0].match_flags = 89 USB_DEVICE_ID_MATCH_VENDOR | USB_DEVICE_ID_MATCH_PRODUCT; 90 91 retval = usb_serial_register_drivers(serial_drivers, 92 "usbserial_generic", generic_device_ids); 93 #endif 94 return retval; 95 } 96 97 void usb_serial_generic_deregister(void) 98 { 99 #ifdef CONFIG_USB_SERIAL_GENERIC 100 usb_serial_deregister_drivers(serial_drivers); 101 #endif 102 } 103 104 int usb_serial_generic_open(struct tty_struct *tty, struct usb_serial_port *port) 105 { 106 int result = 0; 107 108 clear_bit(USB_SERIAL_THROTTLED, &port->flags); 109 110 if (port->bulk_in_size) 111 result = usb_serial_generic_submit_read_urbs(port, GFP_KERNEL); 112 113 return result; 114 } 115 EXPORT_SYMBOL_GPL(usb_serial_generic_open); 116 117 void usb_serial_generic_close(struct usb_serial_port *port) 118 { 119 unsigned long flags; 120 int i; 121 122 if (port->bulk_out_size) { 123 for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) 124 usb_kill_urb(port->write_urbs[i]); 125 126 spin_lock_irqsave(&port->lock, flags); 127 kfifo_reset_out(&port->write_fifo); 128 spin_unlock_irqrestore(&port->lock, flags); 129 } 130 if (port->bulk_in_size) { 131 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) 132 usb_kill_urb(port->read_urbs[i]); 133 } 134 } 135 EXPORT_SYMBOL_GPL(usb_serial_generic_close); 136 137 int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port, 138 void *dest, size_t size) 139 { 140 return kfifo_out_locked(&port->write_fifo, dest, size, &port->lock); 141 } 142 143 /** 144 * usb_serial_generic_write_start - start writing buffered data 145 * @port: usb-serial port 146 * @mem_flags: flags to use for memory allocations 147 * 148 * Serialised using USB_SERIAL_WRITE_BUSY flag. 149 * 150 * Return: Zero on success or if busy, otherwise a negative errno value. 151 */ 152 int usb_serial_generic_write_start(struct usb_serial_port *port, 153 gfp_t mem_flags) 154 { 155 struct urb *urb; 156 int count, result; 157 unsigned long flags; 158 int i; 159 160 if (test_and_set_bit_lock(USB_SERIAL_WRITE_BUSY, &port->flags)) 161 return 0; 162 retry: 163 spin_lock_irqsave(&port->lock, flags); 164 if (!port->write_urbs_free || !kfifo_len(&port->write_fifo)) { 165 clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags); 166 spin_unlock_irqrestore(&port->lock, flags); 167 return 0; 168 } 169 i = (int)find_first_bit(&port->write_urbs_free, 170 ARRAY_SIZE(port->write_urbs)); 171 spin_unlock_irqrestore(&port->lock, flags); 172 173 urb = port->write_urbs[i]; 174 count = port->serial->type->prepare_write_buffer(port, 175 urb->transfer_buffer, 176 port->bulk_out_size); 177 urb->transfer_buffer_length = count; 178 usb_serial_debug_data(&port->dev, __func__, count, urb->transfer_buffer); 179 spin_lock_irqsave(&port->lock, flags); 180 port->tx_bytes += count; 181 spin_unlock_irqrestore(&port->lock, flags); 182 183 clear_bit(i, &port->write_urbs_free); 184 result = usb_submit_urb(urb, mem_flags); 185 if (result) { 186 dev_err_console(port, "%s - error submitting urb: %d\n", 187 __func__, result); 188 set_bit(i, &port->write_urbs_free); 189 spin_lock_irqsave(&port->lock, flags); 190 port->tx_bytes -= count; 191 spin_unlock_irqrestore(&port->lock, flags); 192 193 clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags); 194 return result; 195 } 196 197 goto retry; /* try sending off another urb */ 198 } 199 EXPORT_SYMBOL_GPL(usb_serial_generic_write_start); 200 201 /** 202 * usb_serial_generic_write - generic write function 203 * @tty: tty for the port 204 * @port: usb-serial port 205 * @buf: data to write 206 * @count: number of bytes to write 207 * 208 * Return: The number of characters buffered, which may be anything from 209 * zero to @count, or a negative errno value. 210 */ 211 int usb_serial_generic_write(struct tty_struct *tty, 212 struct usb_serial_port *port, const unsigned char *buf, int count) 213 { 214 int result; 215 216 if (!port->bulk_out_size) 217 return -ENODEV; 218 219 if (!count) 220 return 0; 221 222 count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock); 223 result = usb_serial_generic_write_start(port, GFP_ATOMIC); 224 if (result) 225 return result; 226 227 return count; 228 } 229 EXPORT_SYMBOL_GPL(usb_serial_generic_write); 230 231 unsigned int usb_serial_generic_write_room(struct tty_struct *tty) 232 { 233 struct usb_serial_port *port = tty->driver_data; 234 unsigned long flags; 235 unsigned int room; 236 237 if (!port->bulk_out_size) 238 return 0; 239 240 spin_lock_irqsave(&port->lock, flags); 241 room = kfifo_avail(&port->write_fifo); 242 spin_unlock_irqrestore(&port->lock, flags); 243 244 dev_dbg(&port->dev, "%s - returns %u\n", __func__, room); 245 return room; 246 } 247 248 unsigned int usb_serial_generic_chars_in_buffer(struct tty_struct *tty) 249 { 250 struct usb_serial_port *port = tty->driver_data; 251 unsigned long flags; 252 unsigned int chars; 253 254 if (!port->bulk_out_size) 255 return 0; 256 257 spin_lock_irqsave(&port->lock, flags); 258 chars = kfifo_len(&port->write_fifo) + port->tx_bytes; 259 spin_unlock_irqrestore(&port->lock, flags); 260 261 dev_dbg(&port->dev, "%s - returns %u\n", __func__, chars); 262 return chars; 263 } 264 EXPORT_SYMBOL_GPL(usb_serial_generic_chars_in_buffer); 265 266 void usb_serial_generic_wait_until_sent(struct tty_struct *tty, long timeout) 267 { 268 struct usb_serial_port *port = tty->driver_data; 269 unsigned int bps; 270 unsigned long period; 271 unsigned long expire; 272 273 bps = tty_get_baud_rate(tty); 274 if (!bps) 275 bps = 9600; /* B0 */ 276 /* 277 * Use a poll-period of roughly the time it takes to send one 278 * character or at least one jiffy. 279 */ 280 period = max_t(unsigned long, (10 * HZ / bps), 1); 281 if (timeout) 282 period = min_t(unsigned long, period, timeout); 283 284 dev_dbg(&port->dev, "%s - timeout = %u ms, period = %u ms\n", 285 __func__, jiffies_to_msecs(timeout), 286 jiffies_to_msecs(period)); 287 expire = jiffies + timeout; 288 while (!port->serial->type->tx_empty(port)) { 289 schedule_timeout_interruptible(period); 290 if (signal_pending(current)) 291 break; 292 if (timeout && time_after(jiffies, expire)) 293 break; 294 } 295 } 296 EXPORT_SYMBOL_GPL(usb_serial_generic_wait_until_sent); 297 298 static int usb_serial_generic_submit_read_urb(struct usb_serial_port *port, 299 int index, gfp_t mem_flags) 300 { 301 int res; 302 303 if (!test_and_clear_bit(index, &port->read_urbs_free)) 304 return 0; 305 306 dev_dbg(&port->dev, "%s - urb %d\n", __func__, index); 307 308 res = usb_submit_urb(port->read_urbs[index], mem_flags); 309 if (res) { 310 if (res != -EPERM && res != -ENODEV) { 311 dev_err(&port->dev, 312 "%s - usb_submit_urb failed: %d\n", 313 __func__, res); 314 } 315 set_bit(index, &port->read_urbs_free); 316 return res; 317 } 318 319 return 0; 320 } 321 322 int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port, 323 gfp_t mem_flags) 324 { 325 int res; 326 int i; 327 328 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) { 329 res = usb_serial_generic_submit_read_urb(port, i, mem_flags); 330 if (res) 331 goto err; 332 } 333 334 return 0; 335 err: 336 for (; i >= 0; --i) 337 usb_kill_urb(port->read_urbs[i]); 338 339 return res; 340 } 341 EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urbs); 342 343 void usb_serial_generic_process_read_urb(struct urb *urb) 344 { 345 struct usb_serial_port *port = urb->context; 346 char *ch = urb->transfer_buffer; 347 int i; 348 349 if (!urb->actual_length) 350 return; 351 /* 352 * The per character mucking around with sysrq path it too slow for 353 * stuff like 3G modems, so shortcircuit it in the 99.9999999% of 354 * cases where the USB serial is not a console anyway. 355 */ 356 if (port->sysrq) { 357 for (i = 0; i < urb->actual_length; i++, ch++) { 358 if (!usb_serial_handle_sysrq_char(port, *ch)) 359 tty_insert_flip_char(&port->port, *ch, TTY_NORMAL); 360 } 361 } else { 362 tty_insert_flip_string(&port->port, ch, urb->actual_length); 363 } 364 tty_flip_buffer_push(&port->port); 365 } 366 EXPORT_SYMBOL_GPL(usb_serial_generic_process_read_urb); 367 368 void usb_serial_generic_read_bulk_callback(struct urb *urb) 369 { 370 struct usb_serial_port *port = urb->context; 371 unsigned char *data = urb->transfer_buffer; 372 bool stopped = false; 373 int status = urb->status; 374 int i; 375 376 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) { 377 if (urb == port->read_urbs[i]) 378 break; 379 } 380 381 dev_dbg(&port->dev, "%s - urb %d, len %d\n", __func__, i, 382 urb->actual_length); 383 switch (status) { 384 case 0: 385 usb_serial_debug_data(&port->dev, __func__, urb->actual_length, 386 data); 387 port->serial->type->process_read_urb(urb); 388 break; 389 case -ENOENT: 390 case -ECONNRESET: 391 case -ESHUTDOWN: 392 dev_dbg(&port->dev, "%s - urb stopped: %d\n", 393 __func__, status); 394 stopped = true; 395 break; 396 case -EPIPE: 397 dev_err(&port->dev, "%s - urb stopped: %d\n", 398 __func__, status); 399 stopped = true; 400 break; 401 default: 402 dev_dbg(&port->dev, "%s - nonzero urb status: %d\n", 403 __func__, status); 404 break; 405 } 406 407 /* 408 * Make sure URB processing is done before marking as free to avoid 409 * racing with unthrottle() on another CPU. Matches the barriers 410 * implied by the test_and_clear_bit() in 411 * usb_serial_generic_submit_read_urb(). 412 */ 413 smp_mb__before_atomic(); 414 set_bit(i, &port->read_urbs_free); 415 /* 416 * Make sure URB is marked as free before checking the throttled flag 417 * to avoid racing with unthrottle() on another CPU. Matches the 418 * smp_mb__after_atomic() in unthrottle(). 419 */ 420 smp_mb__after_atomic(); 421 422 if (stopped) 423 return; 424 425 if (test_bit(USB_SERIAL_THROTTLED, &port->flags)) 426 return; 427 428 usb_serial_generic_submit_read_urb(port, i, GFP_ATOMIC); 429 } 430 EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback); 431 432 void usb_serial_generic_write_bulk_callback(struct urb *urb) 433 { 434 unsigned long flags; 435 struct usb_serial_port *port = urb->context; 436 int status = urb->status; 437 int i; 438 439 for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) { 440 if (port->write_urbs[i] == urb) 441 break; 442 } 443 spin_lock_irqsave(&port->lock, flags); 444 port->tx_bytes -= urb->transfer_buffer_length; 445 set_bit(i, &port->write_urbs_free); 446 spin_unlock_irqrestore(&port->lock, flags); 447 448 switch (status) { 449 case 0: 450 break; 451 case -ENOENT: 452 case -ECONNRESET: 453 case -ESHUTDOWN: 454 dev_dbg(&port->dev, "%s - urb stopped: %d\n", 455 __func__, status); 456 return; 457 case -EPIPE: 458 dev_err_console(port, "%s - urb stopped: %d\n", 459 __func__, status); 460 return; 461 default: 462 dev_err_console(port, "%s - nonzero urb status: %d\n", 463 __func__, status); 464 break; 465 } 466 467 usb_serial_generic_write_start(port, GFP_ATOMIC); 468 usb_serial_port_softint(port); 469 } 470 EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback); 471 472 void usb_serial_generic_throttle(struct tty_struct *tty) 473 { 474 struct usb_serial_port *port = tty->driver_data; 475 476 set_bit(USB_SERIAL_THROTTLED, &port->flags); 477 } 478 EXPORT_SYMBOL_GPL(usb_serial_generic_throttle); 479 480 void usb_serial_generic_unthrottle(struct tty_struct *tty) 481 { 482 struct usb_serial_port *port = tty->driver_data; 483 484 clear_bit(USB_SERIAL_THROTTLED, &port->flags); 485 486 /* 487 * Matches the smp_mb__after_atomic() in 488 * usb_serial_generic_read_bulk_callback(). 489 */ 490 smp_mb__after_atomic(); 491 492 usb_serial_generic_submit_read_urbs(port, GFP_KERNEL); 493 } 494 EXPORT_SYMBOL_GPL(usb_serial_generic_unthrottle); 495 496 static bool usb_serial_generic_msr_changed(struct tty_struct *tty, 497 unsigned long arg, struct async_icount *cprev) 498 { 499 struct usb_serial_port *port = tty->driver_data; 500 struct async_icount cnow; 501 unsigned long flags; 502 bool ret; 503 504 /* 505 * Use tty-port initialised flag to detect all hangups including the 506 * one generated at USB-device disconnect. 507 */ 508 if (!tty_port_initialized(&port->port)) 509 return true; 510 511 spin_lock_irqsave(&port->lock, flags); 512 cnow = port->icount; /* atomic copy*/ 513 spin_unlock_irqrestore(&port->lock, flags); 514 515 ret = ((arg & TIOCM_RNG) && (cnow.rng != cprev->rng)) || 516 ((arg & TIOCM_DSR) && (cnow.dsr != cprev->dsr)) || 517 ((arg & TIOCM_CD) && (cnow.dcd != cprev->dcd)) || 518 ((arg & TIOCM_CTS) && (cnow.cts != cprev->cts)); 519 520 *cprev = cnow; 521 522 return ret; 523 } 524 525 int usb_serial_generic_tiocmiwait(struct tty_struct *tty, unsigned long arg) 526 { 527 struct usb_serial_port *port = tty->driver_data; 528 struct async_icount cnow; 529 unsigned long flags; 530 int ret; 531 532 spin_lock_irqsave(&port->lock, flags); 533 cnow = port->icount; /* atomic copy */ 534 spin_unlock_irqrestore(&port->lock, flags); 535 536 ret = wait_event_interruptible(port->port.delta_msr_wait, 537 usb_serial_generic_msr_changed(tty, arg, &cnow)); 538 if (!ret && !tty_port_initialized(&port->port)) 539 ret = -EIO; 540 541 return ret; 542 } 543 EXPORT_SYMBOL_GPL(usb_serial_generic_tiocmiwait); 544 545 int usb_serial_generic_get_icount(struct tty_struct *tty, 546 struct serial_icounter_struct *icount) 547 { 548 struct usb_serial_port *port = tty->driver_data; 549 struct async_icount cnow; 550 unsigned long flags; 551 552 spin_lock_irqsave(&port->lock, flags); 553 cnow = port->icount; /* atomic copy */ 554 spin_unlock_irqrestore(&port->lock, flags); 555 556 icount->cts = cnow.cts; 557 icount->dsr = cnow.dsr; 558 icount->rng = cnow.rng; 559 icount->dcd = cnow.dcd; 560 icount->tx = cnow.tx; 561 icount->rx = cnow.rx; 562 icount->frame = cnow.frame; 563 icount->parity = cnow.parity; 564 icount->overrun = cnow.overrun; 565 icount->brk = cnow.brk; 566 icount->buf_overrun = cnow.buf_overrun; 567 568 return 0; 569 } 570 EXPORT_SYMBOL_GPL(usb_serial_generic_get_icount); 571 572 #if defined(CONFIG_USB_SERIAL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ) 573 int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch) 574 { 575 if (port->sysrq) { 576 if (ch && time_before(jiffies, port->sysrq)) { 577 handle_sysrq(ch); 578 port->sysrq = 0; 579 return 1; 580 } 581 port->sysrq = 0; 582 } 583 return 0; 584 } 585 EXPORT_SYMBOL_GPL(usb_serial_handle_sysrq_char); 586 587 int usb_serial_handle_break(struct usb_serial_port *port) 588 { 589 if (!port->port.console) 590 return 0; 591 592 if (!port->sysrq) { 593 port->sysrq = jiffies + HZ*5; 594 return 1; 595 } 596 port->sysrq = 0; 597 return 0; 598 } 599 EXPORT_SYMBOL_GPL(usb_serial_handle_break); 600 #endif 601 602 /** 603 * usb_serial_handle_dcd_change - handle a change of carrier detect state 604 * @port: usb-serial port 605 * @tty: tty for the port 606 * @status: new carrier detect status, nonzero if active 607 */ 608 void usb_serial_handle_dcd_change(struct usb_serial_port *port, 609 struct tty_struct *tty, unsigned int status) 610 { 611 dev_dbg(&port->dev, "%s - status %d\n", __func__, status); 612 613 if (tty) { 614 struct tty_ldisc *ld = tty_ldisc_ref(tty); 615 616 if (ld) { 617 if (ld->ops->dcd_change) 618 ld->ops->dcd_change(tty, status); 619 tty_ldisc_deref(ld); 620 } 621 } 622 623 if (status) 624 wake_up_interruptible(&port->port.open_wait); 625 else if (tty && !C_CLOCAL(tty)) 626 tty_hangup(tty); 627 } 628 EXPORT_SYMBOL_GPL(usb_serial_handle_dcd_change); 629 630 int usb_serial_generic_resume(struct usb_serial *serial) 631 { 632 struct usb_serial_port *port; 633 int i, c = 0, r; 634 635 for (i = 0; i < serial->num_ports; i++) { 636 port = serial->port[i]; 637 if (!tty_port_initialized(&port->port)) 638 continue; 639 640 if (port->bulk_in_size) { 641 r = usb_serial_generic_submit_read_urbs(port, 642 GFP_NOIO); 643 if (r < 0) 644 c++; 645 } 646 647 if (port->bulk_out_size) { 648 r = usb_serial_generic_write_start(port, GFP_NOIO); 649 if (r < 0) 650 c++; 651 } 652 } 653 654 return c ? -EIO : 0; 655 } 656 EXPORT_SYMBOL_GPL(usb_serial_generic_resume); 657