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/uaccess.h>
21#include <linux/kfifo.h>
22#include <linux/serial.h>
23
24#ifdef CONFIG_USB_SERIAL_GENERIC
25
26static __u16 vendor = 0x05f9;
27static __u16 product = 0xffff;
28
29module_param(vendor, ushort, 0);
30MODULE_PARM_DESC(vendor, "User specified USB idVendor");
31
32module_param(product, ushort, 0);
33MODULE_PARM_DESC(product, "User specified USB idProduct");
34
35static struct usb_device_id generic_device_ids[2]; /* Initially all zeroes. */
36
37static int usb_serial_generic_probe(struct usb_serial *serial,
38 const struct usb_device_id *id)
39{
40 struct device *dev = &serial->interface->dev;
41
42 dev_info(dev, "The \"generic\" usb-serial driver is only for testing and one-off prototypes.\n");
43 dev_info(dev, "Tell linux-usb@vger.kernel.org to add your device to a proper driver.\n");
44
45 return 0;
46}
47
48static int usb_serial_generic_calc_num_ports(struct usb_serial *serial,
49 struct usb_serial_endpoints *epds)
50{
51 struct device *dev = &serial->interface->dev;
52 int num_ports;
53
54 num_ports = max(epds->num_bulk_in, epds->num_bulk_out);
55
56 if (num_ports == 0) {
57 dev_err(dev, "device has no bulk endpoints\n");
58 return -ENODEV;
59 }
60
61 return num_ports;
62}
63
64static struct usb_serial_driver usb_serial_generic_device = {
65 .driver = {
66 .name = "generic",
67 },
68 .id_table = generic_device_ids,
69 .probe = usb_serial_generic_probe,
70 .calc_num_ports = usb_serial_generic_calc_num_ports,
71 .throttle = usb_serial_generic_throttle,
72 .unthrottle = usb_serial_generic_unthrottle,
73 .resume = usb_serial_generic_resume,
74};
75
76static struct usb_serial_driver * const serial_drivers[] = {
77 &usb_serial_generic_device, NULL
78};
79
80#endif
81
82int usb_serial_generic_register(void)
83{
84 int retval = 0;
85
86#ifdef CONFIG_USB_SERIAL_GENERIC
87 generic_device_ids[0].idVendor = vendor;
88 generic_device_ids[0].idProduct = product;
89 generic_device_ids[0].match_flags =
90 USB_DEVICE_ID_MATCH_VENDOR | USB_DEVICE_ID_MATCH_PRODUCT;
91
92 retval = usb_serial_register_drivers(serial_drivers,
93 "usbserial_generic", generic_device_ids);
94#endif
95 return retval;
96}
97
98void usb_serial_generic_deregister(void)
99{
100#ifdef CONFIG_USB_SERIAL_GENERIC
101 usb_serial_deregister_drivers(serial_drivers);
102#endif
103}
104
105int usb_serial_generic_open(struct tty_struct *tty, struct usb_serial_port *port)
106{
107 int result = 0;
108
109 clear_bit(USB_SERIAL_THROTTLED, addr: &port->flags);
110
111 if (port->bulk_in_size)
112 result = usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
113
114 return result;
115}
116EXPORT_SYMBOL_GPL(usb_serial_generic_open);
117
118void usb_serial_generic_close(struct usb_serial_port *port)
119{
120 unsigned long flags;
121 int i;
122
123 if (port->bulk_out_size) {
124 for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
125 usb_kill_urb(urb: port->write_urbs[i]);
126
127 spin_lock_irqsave(&port->lock, flags);
128 kfifo_reset_out(&port->write_fifo);
129 spin_unlock_irqrestore(lock: &port->lock, flags);
130 }
131 if (port->bulk_in_size) {
132 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i)
133 usb_kill_urb(urb: port->read_urbs[i]);
134 }
135}
136EXPORT_SYMBOL_GPL(usb_serial_generic_close);
137
138int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
139 void *dest, size_t size)
140{
141 return kfifo_out_locked(&port->write_fifo, dest, size, &port->lock);
142}
143
144/**
145 * usb_serial_generic_write_start - start writing buffered data
146 * @port: usb-serial port
147 * @mem_flags: flags to use for memory allocations
148 *
149 * Serialised using USB_SERIAL_WRITE_BUSY flag.
150 *
151 * Return: Zero on success or if busy, otherwise a negative errno value.
152 */
153int usb_serial_generic_write_start(struct usb_serial_port *port,
154 gfp_t mem_flags)
155{
156 struct urb *urb;
157 int count, result;
158 unsigned long flags;
159 int i;
160
161 if (test_and_set_bit_lock(USB_SERIAL_WRITE_BUSY, addr: &port->flags))
162 return 0;
163retry:
164 spin_lock_irqsave(&port->lock, flags);
165 if (!port->write_urbs_free || !kfifo_len(&port->write_fifo)) {
166 clear_bit_unlock(USB_SERIAL_WRITE_BUSY, addr: &port->flags);
167 spin_unlock_irqrestore(lock: &port->lock, flags);
168 return 0;
169 }
170 i = (int)find_first_bit(addr: &port->write_urbs_free,
171 ARRAY_SIZE(port->write_urbs));
172 spin_unlock_irqrestore(lock: &port->lock, flags);
173
174 urb = port->write_urbs[i];
175 count = port->serial->type->prepare_write_buffer(port,
176 urb->transfer_buffer,
177 port->bulk_out_size);
178 urb->transfer_buffer_length = count;
179 usb_serial_debug_data(dev: &port->dev, function: __func__, size: count, data: urb->transfer_buffer);
180 spin_lock_irqsave(&port->lock, flags);
181 port->tx_bytes += count;
182 spin_unlock_irqrestore(lock: &port->lock, flags);
183
184 clear_bit(nr: i, addr: &port->write_urbs_free);
185 result = usb_submit_urb(urb, mem_flags);
186 if (result) {
187 dev_err_console(port, "%s - error submitting urb: %d\n",
188 __func__, result);
189 set_bit(nr: i, addr: &port->write_urbs_free);
190 spin_lock_irqsave(&port->lock, flags);
191 port->tx_bytes -= count;
192 spin_unlock_irqrestore(lock: &port->lock, flags);
193
194 clear_bit_unlock(USB_SERIAL_WRITE_BUSY, addr: &port->flags);
195 return result;
196 }
197
198 goto retry; /* try sending off another urb */
199}
200EXPORT_SYMBOL_GPL(usb_serial_generic_write_start);
201
202/**
203 * usb_serial_generic_write - generic write function
204 * @tty: tty for the port
205 * @port: usb-serial port
206 * @buf: data to write
207 * @count: number of bytes to write
208 *
209 * Return: The number of characters buffered, which may be anything from
210 * zero to @count, or a negative errno value.
211 */
212int usb_serial_generic_write(struct tty_struct *tty,
213 struct usb_serial_port *port, const unsigned char *buf, int count)
214{
215 int result;
216
217 if (!port->bulk_out_size)
218 return -ENODEV;
219
220 if (!count)
221 return 0;
222
223 count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
224 result = usb_serial_generic_write_start(port, GFP_ATOMIC);
225 if (result)
226 return result;
227
228 return count;
229}
230EXPORT_SYMBOL_GPL(usb_serial_generic_write);
231
232unsigned int usb_serial_generic_write_room(struct tty_struct *tty)
233{
234 struct usb_serial_port *port = tty->driver_data;
235 unsigned long flags;
236 unsigned int room;
237
238 if (!port->bulk_out_size)
239 return 0;
240
241 spin_lock_irqsave(&port->lock, flags);
242 room = kfifo_avail(&port->write_fifo);
243 spin_unlock_irqrestore(lock: &port->lock, flags);
244
245 dev_dbg(&port->dev, "%s - returns %u\n", __func__, room);
246 return room;
247}
248
249unsigned int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
250{
251 struct usb_serial_port *port = tty->driver_data;
252 unsigned long flags;
253 unsigned int chars;
254
255 if (!port->bulk_out_size)
256 return 0;
257
258 spin_lock_irqsave(&port->lock, flags);
259 chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
260 spin_unlock_irqrestore(lock: &port->lock, flags);
261
262 dev_dbg(&port->dev, "%s - returns %u\n", __func__, chars);
263 return chars;
264}
265EXPORT_SYMBOL_GPL(usb_serial_generic_chars_in_buffer);
266
267void usb_serial_generic_wait_until_sent(struct tty_struct *tty, long timeout)
268{
269 struct usb_serial_port *port = tty->driver_data;
270 unsigned int bps;
271 unsigned long period;
272 unsigned long expire;
273
274 bps = tty_get_baud_rate(tty);
275 if (!bps)
276 bps = 9600; /* B0 */
277 /*
278 * Use a poll-period of roughly the time it takes to send one
279 * character or at least one jiffy.
280 */
281 period = max_t(unsigned long, (10 * HZ / bps), 1);
282 if (timeout)
283 period = min_t(unsigned long, period, timeout);
284
285 dev_dbg(&port->dev, "%s - timeout = %u ms, period = %u ms\n",
286 __func__, jiffies_to_msecs(timeout),
287 jiffies_to_msecs(period));
288 expire = jiffies + timeout;
289 while (!port->serial->type->tx_empty(port)) {
290 schedule_timeout_interruptible(timeout: period);
291 if (signal_pending(current))
292 break;
293 if (timeout && time_after(jiffies, expire))
294 break;
295 }
296}
297EXPORT_SYMBOL_GPL(usb_serial_generic_wait_until_sent);
298
299static int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
300 int index, gfp_t mem_flags)
301{
302 int res;
303
304 if (!test_and_clear_bit(nr: index, addr: &port->read_urbs_free))
305 return 0;
306
307 dev_dbg(&port->dev, "%s - urb %d\n", __func__, index);
308
309 res = usb_submit_urb(urb: port->read_urbs[index], mem_flags);
310 if (res) {
311 if (res != -EPERM && res != -ENODEV) {
312 dev_err(&port->dev,
313 "%s - usb_submit_urb failed: %d\n",
314 __func__, res);
315 }
316 set_bit(nr: index, addr: &port->read_urbs_free);
317 return res;
318 }
319
320 return 0;
321}
322
323int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port,
324 gfp_t mem_flags)
325{
326 int res;
327 int i;
328
329 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
330 res = usb_serial_generic_submit_read_urb(port, index: i, mem_flags);
331 if (res)
332 goto err;
333 }
334
335 return 0;
336err:
337 for (; i >= 0; --i)
338 usb_kill_urb(urb: port->read_urbs[i]);
339
340 return res;
341}
342EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urbs);
343
344void usb_serial_generic_process_read_urb(struct urb *urb)
345{
346 struct usb_serial_port *port = urb->context;
347 char *ch = urb->transfer_buffer;
348 int i;
349
350 if (!urb->actual_length)
351 return;
352 /*
353 * The per character mucking around with sysrq path it too slow for
354 * stuff like 3G modems, so shortcircuit it in the 99.9999999% of
355 * cases where the USB serial is not a console anyway.
356 */
357 if (port->sysrq) {
358 for (i = 0; i < urb->actual_length; i++, ch++) {
359 if (!usb_serial_handle_sysrq_char(port, ch: *ch))
360 tty_insert_flip_char(port: &port->port, ch: *ch, TTY_NORMAL);
361 }
362 } else {
363 tty_insert_flip_string(port: &port->port, chars: ch, size: urb->actual_length);
364 }
365 tty_flip_buffer_push(port: &port->port);
366}
367EXPORT_SYMBOL_GPL(usb_serial_generic_process_read_urb);
368
369void usb_serial_generic_read_bulk_callback(struct urb *urb)
370{
371 struct usb_serial_port *port = urb->context;
372 unsigned char *data = urb->transfer_buffer;
373 bool stopped = false;
374 int status = urb->status;
375 int i;
376
377 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
378 if (urb == port->read_urbs[i])
379 break;
380 }
381
382 dev_dbg(&port->dev, "%s - urb %d, len %d\n", __func__, i,
383 urb->actual_length);
384 switch (status) {
385 case 0:
386 usb_serial_debug_data(dev: &port->dev, function: __func__, size: urb->actual_length,
387 data);
388 port->serial->type->process_read_urb(urb);
389 break;
390 case -ENOENT:
391 case -ECONNRESET:
392 case -ESHUTDOWN:
393 dev_dbg(&port->dev, "%s - urb stopped: %d\n",
394 __func__, status);
395 stopped = true;
396 break;
397 case -EPIPE:
398 dev_err(&port->dev, "%s - urb stopped: %d\n",
399 __func__, status);
400 stopped = true;
401 break;
402 default:
403 dev_dbg(&port->dev, "%s - nonzero urb status: %d\n",
404 __func__, status);
405 break;
406 }
407
408 /*
409 * Make sure URB processing is done before marking as free to avoid
410 * racing with unthrottle() on another CPU. Matches the barriers
411 * implied by the test_and_clear_bit() in
412 * usb_serial_generic_submit_read_urb().
413 */
414 smp_mb__before_atomic();
415 set_bit(nr: i, addr: &port->read_urbs_free);
416 /*
417 * Make sure URB is marked as free before checking the throttled flag
418 * to avoid racing with unthrottle() on another CPU. Matches the
419 * smp_mb__after_atomic() in unthrottle().
420 */
421 smp_mb__after_atomic();
422
423 if (stopped)
424 return;
425
426 if (test_bit(USB_SERIAL_THROTTLED, &port->flags))
427 return;
428
429 usb_serial_generic_submit_read_urb(port, index: i, GFP_ATOMIC);
430}
431EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback);
432
433void usb_serial_generic_write_bulk_callback(struct urb *urb)
434{
435 unsigned long flags;
436 struct usb_serial_port *port = urb->context;
437 int status = urb->status;
438 int i;
439
440 for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) {
441 if (port->write_urbs[i] == urb)
442 break;
443 }
444 spin_lock_irqsave(&port->lock, flags);
445 port->tx_bytes -= urb->transfer_buffer_length;
446 set_bit(nr: i, addr: &port->write_urbs_free);
447 spin_unlock_irqrestore(lock: &port->lock, flags);
448
449 switch (status) {
450 case 0:
451 break;
452 case -ENOENT:
453 case -ECONNRESET:
454 case -ESHUTDOWN:
455 dev_dbg(&port->dev, "%s - urb stopped: %d\n",
456 __func__, status);
457 return;
458 case -EPIPE:
459 dev_err_console(port, "%s - urb stopped: %d\n",
460 __func__, status);
461 return;
462 default:
463 dev_err_console(port, "%s - nonzero urb status: %d\n",
464 __func__, status);
465 break;
466 }
467
468 usb_serial_generic_write_start(port, GFP_ATOMIC);
469 usb_serial_port_softint(port);
470}
471EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback);
472
473void usb_serial_generic_throttle(struct tty_struct *tty)
474{
475 struct usb_serial_port *port = tty->driver_data;
476
477 set_bit(USB_SERIAL_THROTTLED, addr: &port->flags);
478}
479EXPORT_SYMBOL_GPL(usb_serial_generic_throttle);
480
481void usb_serial_generic_unthrottle(struct tty_struct *tty)
482{
483 struct usb_serial_port *port = tty->driver_data;
484
485 clear_bit(USB_SERIAL_THROTTLED, addr: &port->flags);
486
487 /*
488 * Matches the smp_mb__after_atomic() in
489 * usb_serial_generic_read_bulk_callback().
490 */
491 smp_mb__after_atomic();
492
493 usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
494}
495EXPORT_SYMBOL_GPL(usb_serial_generic_unthrottle);
496
497static bool usb_serial_generic_msr_changed(struct tty_struct *tty,
498 unsigned long arg, struct async_icount *cprev)
499{
500 struct usb_serial_port *port = tty->driver_data;
501 struct async_icount cnow;
502 unsigned long flags;
503 bool ret;
504
505 /*
506 * Use tty-port initialised flag to detect all hangups including the
507 * one generated at USB-device disconnect.
508 */
509 if (!tty_port_initialized(port: &port->port))
510 return true;
511
512 spin_lock_irqsave(&port->lock, flags);
513 cnow = port->icount; /* atomic copy*/
514 spin_unlock_irqrestore(lock: &port->lock, flags);
515
516 ret = ((arg & TIOCM_RNG) && (cnow.rng != cprev->rng)) ||
517 ((arg & TIOCM_DSR) && (cnow.dsr != cprev->dsr)) ||
518 ((arg & TIOCM_CD) && (cnow.dcd != cprev->dcd)) ||
519 ((arg & TIOCM_CTS) && (cnow.cts != cprev->cts));
520
521 *cprev = cnow;
522
523 return ret;
524}
525
526int usb_serial_generic_tiocmiwait(struct tty_struct *tty, unsigned long arg)
527{
528 struct usb_serial_port *port = tty->driver_data;
529 struct async_icount cnow;
530 unsigned long flags;
531 int ret;
532
533 spin_lock_irqsave(&port->lock, flags);
534 cnow = port->icount; /* atomic copy */
535 spin_unlock_irqrestore(lock: &port->lock, flags);
536
537 ret = wait_event_interruptible(port->port.delta_msr_wait,
538 usb_serial_generic_msr_changed(tty, arg, &cnow));
539 if (!ret && !tty_port_initialized(port: &port->port))
540 ret = -EIO;
541
542 return ret;
543}
544EXPORT_SYMBOL_GPL(usb_serial_generic_tiocmiwait);
545
546int usb_serial_generic_get_icount(struct tty_struct *tty,
547 struct serial_icounter_struct *icount)
548{
549 struct usb_serial_port *port = tty->driver_data;
550 struct async_icount cnow;
551 unsigned long flags;
552
553 spin_lock_irqsave(&port->lock, flags);
554 cnow = port->icount; /* atomic copy */
555 spin_unlock_irqrestore(lock: &port->lock, flags);
556
557 icount->cts = cnow.cts;
558 icount->dsr = cnow.dsr;
559 icount->rng = cnow.rng;
560 icount->dcd = cnow.dcd;
561 icount->tx = cnow.tx;
562 icount->rx = cnow.rx;
563 icount->frame = cnow.frame;
564 icount->parity = cnow.parity;
565 icount->overrun = cnow.overrun;
566 icount->brk = cnow.brk;
567 icount->buf_overrun = cnow.buf_overrun;
568
569 return 0;
570}
571EXPORT_SYMBOL_GPL(usb_serial_generic_get_icount);
572
573#if defined(CONFIG_USB_SERIAL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
574int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
575{
576 if (port->sysrq) {
577 if (ch && time_before(jiffies, port->sysrq)) {
578 handle_sysrq(key: ch);
579 port->sysrq = 0;
580 return 1;
581 }
582 port->sysrq = 0;
583 }
584 return 0;
585}
586EXPORT_SYMBOL_GPL(usb_serial_handle_sysrq_char);
587
588int usb_serial_handle_break(struct usb_serial_port *port)
589{
590 if (!port->port.console)
591 return 0;
592
593 if (!port->sysrq) {
594 port->sysrq = jiffies + HZ*5;
595 return 1;
596 }
597 port->sysrq = 0;
598 return 0;
599}
600EXPORT_SYMBOL_GPL(usb_serial_handle_break);
601#endif
602
603/**
604 * usb_serial_handle_dcd_change - handle a change of carrier detect state
605 * @port: usb-serial port
606 * @tty: tty for the port
607 * @status: new carrier detect status, nonzero if active
608 */
609void usb_serial_handle_dcd_change(struct usb_serial_port *port,
610 struct tty_struct *tty, unsigned int status)
611{
612 dev_dbg(&port->dev, "%s - status %d\n", __func__, status);
613
614 if (tty) {
615 struct tty_ldisc *ld = tty_ldisc_ref(tty);
616
617 if (ld) {
618 if (ld->ops->dcd_change)
619 ld->ops->dcd_change(tty, status);
620 tty_ldisc_deref(ld);
621 }
622 }
623
624 if (status)
625 wake_up_interruptible(&port->port.open_wait);
626 else if (tty && !C_CLOCAL(tty))
627 tty_hangup(tty);
628}
629EXPORT_SYMBOL_GPL(usb_serial_handle_dcd_change);
630
631int usb_serial_generic_resume(struct usb_serial *serial)
632{
633 struct usb_serial_port *port;
634 int i, c = 0, r;
635
636 for (i = 0; i < serial->num_ports; i++) {
637 port = serial->port[i];
638 if (!tty_port_initialized(port: &port->port))
639 continue;
640
641 if (port->bulk_in_size) {
642 r = usb_serial_generic_submit_read_urbs(port,
643 GFP_NOIO);
644 if (r < 0)
645 c++;
646 }
647
648 if (port->bulk_out_size) {
649 r = usb_serial_generic_write_start(port, GFP_NOIO);
650 if (r < 0)
651 c++;
652 }
653 }
654
655 return c ? -EIO : 0;
656}
657EXPORT_SYMBOL_GPL(usb_serial_generic_resume);
658

source code of linux/drivers/usb/serial/generic.c