1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
4 * Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
5 * Copyright 2009, Boris Hajduk <boris@hajduk.org>
6 *
7 * ch341.c implements a serial port driver for the Winchiphead CH341.
8 *
9 * The CH341 device can be used to implement an RS232 asynchronous
10 * serial port, an IEEE-1284 parallel printer port or a memory-like
11 * interface. In all cases the CH341 supports an I2C interface as well.
12 * This driver only supports the asynchronous serial interface.
13 */
14
15#include <linux/kernel.h>
16#include <linux/tty.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/usb.h>
20#include <linux/usb/serial.h>
21#include <linux/serial.h>
22#include <asm/unaligned.h>
23
24#define DEFAULT_BAUD_RATE 9600
25#define DEFAULT_TIMEOUT 1000
26
27/* flags for IO-Bits */
28#define CH341_BIT_RTS (1 << 6)
29#define CH341_BIT_DTR (1 << 5)
30
31/******************************/
32/* interrupt pipe definitions */
33/******************************/
34/* always 4 interrupt bytes */
35/* first irq byte normally 0x08 */
36/* second irq byte base 0x7d + below */
37/* third irq byte base 0x94 + below */
38/* fourth irq byte normally 0xee */
39
40/* second interrupt byte */
41#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
42
43/* status returned in third interrupt answer byte, inverted in data
44 from irq */
45#define CH341_BIT_CTS 0x01
46#define CH341_BIT_DSR 0x02
47#define CH341_BIT_RI 0x04
48#define CH341_BIT_DCD 0x08
49#define CH341_BITS_MODEM_STAT 0x0f /* all bits */
50
51/* Break support - the information used to implement this was gleaned from
52 * the Net/FreeBSD uchcom.c driver by Takanori Watanabe. Domo arigato.
53 */
54
55#define CH341_REQ_READ_VERSION 0x5F
56#define CH341_REQ_WRITE_REG 0x9A
57#define CH341_REQ_READ_REG 0x95
58#define CH341_REQ_SERIAL_INIT 0xA1
59#define CH341_REQ_MODEM_CTRL 0xA4
60
61#define CH341_REG_BREAK 0x05
62#define CH341_REG_PRESCALER 0x12
63#define CH341_REG_DIVISOR 0x13
64#define CH341_REG_LCR 0x18
65#define CH341_REG_LCR2 0x25
66
67#define CH341_NBREAK_BITS 0x01
68
69#define CH341_LCR_ENABLE_RX 0x80
70#define CH341_LCR_ENABLE_TX 0x40
71#define CH341_LCR_MARK_SPACE 0x20
72#define CH341_LCR_PAR_EVEN 0x10
73#define CH341_LCR_ENABLE_PAR 0x08
74#define CH341_LCR_STOP_BITS_2 0x04
75#define CH341_LCR_CS8 0x03
76#define CH341_LCR_CS7 0x02
77#define CH341_LCR_CS6 0x01
78#define CH341_LCR_CS5 0x00
79
80#define CH341_QUIRK_LIMITED_PRESCALER BIT(0)
81#define CH341_QUIRK_SIMULATE_BREAK BIT(1)
82
83static const struct usb_device_id id_table[] = {
84 { USB_DEVICE(0x1a86, 0x5523) },
85 { USB_DEVICE(0x1a86, 0x7522) },
86 { USB_DEVICE(0x1a86, 0x7523) },
87 { USB_DEVICE(0x2184, 0x0057) },
88 { USB_DEVICE(0x4348, 0x5523) },
89 { USB_DEVICE(0x9986, 0x7523) },
90 { },
91};
92MODULE_DEVICE_TABLE(usb, id_table);
93
94struct ch341_private {
95 spinlock_t lock; /* access lock */
96 unsigned baud_rate; /* set baud rate */
97 u8 mcr;
98 u8 msr;
99 u8 lcr;
100 unsigned long quirks;
101 unsigned long break_end;
102};
103
104static void ch341_set_termios(struct tty_struct *tty,
105 struct usb_serial_port *port,
106 struct ktermios *old_termios);
107
108static int ch341_control_out(struct usb_device *dev, u8 request,
109 u16 value, u16 index)
110{
111 int r;
112
113 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
114 request, value, index);
115
116 r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
117 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
118 value, index, NULL, 0, DEFAULT_TIMEOUT);
119 if (r < 0)
120 dev_err(&dev->dev, "failed to send control message: %d\n", r);
121
122 return r;
123}
124
125static int ch341_control_in(struct usb_device *dev,
126 u8 request, u16 value, u16 index,
127 char *buf, unsigned bufsize)
128{
129 int r;
130
131 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
132 request, value, index, bufsize);
133
134 r = usb_control_msg_recv(dev, 0, request,
135 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
136 value, index, buf, bufsize, DEFAULT_TIMEOUT,
137 GFP_KERNEL);
138 if (r) {
139 dev_err(&dev->dev, "failed to receive control message: %d\n",
140 r);
141 return r;
142 }
143
144 return 0;
145}
146
147#define CH341_CLKRATE 48000000
148#define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
149#define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
150
151static const speed_t ch341_min_rates[] = {
152 CH341_MIN_RATE(0),
153 CH341_MIN_RATE(1),
154 CH341_MIN_RATE(2),
155 CH341_MIN_RATE(3),
156};
157
158/* Supported range is 46 to 3000000 bps. */
159#define CH341_MIN_BPS DIV_ROUND_UP(CH341_CLKRATE, CH341_CLK_DIV(0, 0) * 256)
160#define CH341_MAX_BPS (CH341_CLKRATE / (CH341_CLK_DIV(3, 0) * 2))
161
162/*
163 * The device line speed is given by the following equation:
164 *
165 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
166 *
167 * 0 <= ps <= 3,
168 * 0 <= fact <= 1,
169 * 2 <= div <= 256 if fact = 0, or
170 * 9 <= div <= 256 if fact = 1
171 */
172static int ch341_get_divisor(struct ch341_private *priv, speed_t speed)
173{
174 unsigned int fact, div, clk_div;
175 bool force_fact0 = false;
176 int ps;
177
178 /*
179 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
180 * sanity checks below redundant.
181 */
182 speed = clamp_val(speed, CH341_MIN_BPS, CH341_MAX_BPS);
183
184 /*
185 * Start with highest possible base clock (fact = 1) that will give a
186 * divisor strictly less than 512.
187 */
188 fact = 1;
189 for (ps = 3; ps >= 0; ps--) {
190 if (speed > ch341_min_rates[ps])
191 break;
192 }
193
194 if (ps < 0)
195 return -EINVAL;
196
197 /* Determine corresponding divisor, rounding down. */
198 clk_div = CH341_CLK_DIV(ps, fact);
199 div = CH341_CLKRATE / (clk_div * speed);
200
201 /* Some devices require a lower base clock if ps < 3. */
202 if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER))
203 force_fact0 = true;
204
205 /* Halve base clock (fact = 0) if required. */
206 if (div < 9 || div > 255 || force_fact0) {
207 div /= 2;
208 clk_div *= 2;
209 fact = 0;
210 }
211
212 if (div < 2)
213 return -EINVAL;
214
215 /*
216 * Pick next divisor if resulting rate is closer to the requested one,
217 * scale up to avoid rounding errors on low rates.
218 */
219 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
220 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
221 div++;
222
223 /*
224 * Prefer lower base clock (fact = 0) if even divisor.
225 *
226 * Note that this makes the receiver more tolerant to errors.
227 */
228 if (fact == 1 && div % 2 == 0) {
229 div /= 2;
230 fact = 0;
231 }
232
233 return (0x100 - div) << 8 | fact << 2 | ps;
234}
235
236static int ch341_set_baudrate_lcr(struct usb_device *dev,
237 struct ch341_private *priv,
238 speed_t baud_rate, u8 lcr)
239{
240 int val;
241 int r;
242
243 if (!baud_rate)
244 return -EINVAL;
245
246 val = ch341_get_divisor(priv, baud_rate);
247 if (val < 0)
248 return -EINVAL;
249
250 /*
251 * CH341A buffers data until a full endpoint-size packet (32 bytes)
252 * has been received unless bit 7 is set.
253 */
254 val |= BIT(7);
255
256 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
257 CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
258 val);
259 if (r)
260 return r;
261
262 /*
263 * Chip versions before version 0x30 as read using
264 * CH341_REQ_READ_VERSION used separate registers for line control
265 * (stop bits, parity and word length). Version 0x30 and above use
266 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
267 */
268 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
269 CH341_REG_LCR2 << 8 | CH341_REG_LCR, lcr);
270 if (r)
271 return r;
272
273 return r;
274}
275
276static int ch341_set_handshake(struct usb_device *dev, u8 control)
277{
278 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
279}
280
281static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
282{
283 const unsigned int size = 2;
284 u8 buffer[2];
285 int r;
286 unsigned long flags;
287
288 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
289 if (r)
290 return r;
291
292 spin_lock_irqsave(&priv->lock, flags);
293 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
294 spin_unlock_irqrestore(&priv->lock, flags);
295
296 return 0;
297}
298
299/* -------------------------------------------------------------------------- */
300
301static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
302{
303 const unsigned int size = 2;
304 u8 buffer[2];
305 int r;
306
307 /* expect two bytes 0x27 0x00 */
308 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
309 if (r)
310 return r;
311 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
312
313 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
314 if (r < 0)
315 return r;
316
317 r = ch341_set_baudrate_lcr(dev, priv, priv->baud_rate, priv->lcr);
318 if (r < 0)
319 return r;
320
321 r = ch341_set_handshake(dev, priv->mcr);
322 if (r < 0)
323 return r;
324
325 return 0;
326}
327
328static int ch341_detect_quirks(struct usb_serial_port *port)
329{
330 struct ch341_private *priv = usb_get_serial_port_data(port);
331 struct usb_device *udev = port->serial->dev;
332 const unsigned int size = 2;
333 unsigned long quirks = 0;
334 u8 buffer[2];
335 int r;
336
337 /*
338 * A subset of CH34x devices does not support all features. The
339 * prescaler is limited and there is no support for sending a RS232
340 * break condition. A read failure when trying to set up the latter is
341 * used to detect these devices.
342 */
343 r = usb_control_msg_recv(udev, 0, CH341_REQ_READ_REG,
344 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
345 CH341_REG_BREAK, 0, &buffer, size,
346 DEFAULT_TIMEOUT, GFP_KERNEL);
347 if (r == -EPIPE) {
348 dev_info(&port->dev, "break control not supported, using simulated break\n");
349 quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK;
350 r = 0;
351 } else if (r) {
352 dev_err(&port->dev, "failed to read break control: %d\n", r);
353 }
354
355 if (quirks) {
356 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
357 priv->quirks |= quirks;
358 }
359
360 return r;
361}
362
363static int ch341_port_probe(struct usb_serial_port *port)
364{
365 struct ch341_private *priv;
366 int r;
367
368 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
369 if (!priv)
370 return -ENOMEM;
371
372 spin_lock_init(&priv->lock);
373 priv->baud_rate = DEFAULT_BAUD_RATE;
374 /*
375 * Some CH340 devices appear unable to change the initial LCR
376 * settings, so set a sane 8N1 default.
377 */
378 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
379
380 r = ch341_configure(port->serial->dev, priv);
381 if (r < 0)
382 goto error;
383
384 usb_set_serial_port_data(port, priv);
385
386 r = ch341_detect_quirks(port);
387 if (r < 0)
388 goto error;
389
390 return 0;
391
392error: kfree(priv);
393 return r;
394}
395
396static void ch341_port_remove(struct usb_serial_port *port)
397{
398 struct ch341_private *priv;
399
400 priv = usb_get_serial_port_data(port);
401 kfree(priv);
402}
403
404static int ch341_carrier_raised(struct usb_serial_port *port)
405{
406 struct ch341_private *priv = usb_get_serial_port_data(port);
407 if (priv->msr & CH341_BIT_DCD)
408 return 1;
409 return 0;
410}
411
412static void ch341_dtr_rts(struct usb_serial_port *port, int on)
413{
414 struct ch341_private *priv = usb_get_serial_port_data(port);
415 unsigned long flags;
416
417 /* drop DTR and RTS */
418 spin_lock_irqsave(&priv->lock, flags);
419 if (on)
420 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
421 else
422 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
423 spin_unlock_irqrestore(&priv->lock, flags);
424 ch341_set_handshake(port->serial->dev, priv->mcr);
425}
426
427static void ch341_close(struct usb_serial_port *port)
428{
429 usb_serial_generic_close(port);
430 usb_kill_urb(port->interrupt_in_urb);
431}
432
433
434/* open this device, set default parameters */
435static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
436{
437 struct ch341_private *priv = usb_get_serial_port_data(port);
438 int r;
439
440 if (tty)
441 ch341_set_termios(tty, port, NULL);
442
443 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
444 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
445 if (r) {
446 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
447 __func__, r);
448 return r;
449 }
450
451 r = ch341_get_status(port->serial->dev, priv);
452 if (r < 0) {
453 dev_err(&port->dev, "failed to read modem status: %d\n", r);
454 goto err_kill_interrupt_urb;
455 }
456
457 r = usb_serial_generic_open(tty, port);
458 if (r)
459 goto err_kill_interrupt_urb;
460
461 return 0;
462
463err_kill_interrupt_urb:
464 usb_kill_urb(port->interrupt_in_urb);
465
466 return r;
467}
468
469/* Old_termios contains the original termios settings and
470 * tty->termios contains the new setting to be used.
471 */
472static void ch341_set_termios(struct tty_struct *tty,
473 struct usb_serial_port *port, struct ktermios *old_termios)
474{
475 struct ch341_private *priv = usb_get_serial_port_data(port);
476 unsigned baud_rate;
477 unsigned long flags;
478 u8 lcr;
479 int r;
480
481 /* redundant changes may cause the chip to lose bytes */
482 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
483 return;
484
485 baud_rate = tty_get_baud_rate(tty);
486
487 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
488
489 switch (C_CSIZE(tty)) {
490 case CS5:
491 lcr |= CH341_LCR_CS5;
492 break;
493 case CS6:
494 lcr |= CH341_LCR_CS6;
495 break;
496 case CS7:
497 lcr |= CH341_LCR_CS7;
498 break;
499 case CS8:
500 lcr |= CH341_LCR_CS8;
501 break;
502 }
503
504 if (C_PARENB(tty)) {
505 lcr |= CH341_LCR_ENABLE_PAR;
506 if (C_PARODD(tty) == 0)
507 lcr |= CH341_LCR_PAR_EVEN;
508 if (C_CMSPAR(tty))
509 lcr |= CH341_LCR_MARK_SPACE;
510 }
511
512 if (C_CSTOPB(tty))
513 lcr |= CH341_LCR_STOP_BITS_2;
514
515 if (baud_rate) {
516 priv->baud_rate = baud_rate;
517
518 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
519 priv->baud_rate, lcr);
520 if (r < 0 && old_termios) {
521 priv->baud_rate = tty_termios_baud_rate(old_termios);
522 tty_termios_copy_hw(&tty->termios, old_termios);
523 } else if (r == 0) {
524 priv->lcr = lcr;
525 }
526 }
527
528 spin_lock_irqsave(&priv->lock, flags);
529 if (C_BAUD(tty) == B0)
530 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
531 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
532 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
533 spin_unlock_irqrestore(&priv->lock, flags);
534
535 ch341_set_handshake(port->serial->dev, priv->mcr);
536}
537
538/*
539 * A subset of all CH34x devices don't support a real break condition and
540 * reading CH341_REG_BREAK fails (see also ch341_detect_quirks). This function
541 * simulates a break condition by lowering the baud rate to the minimum
542 * supported by the hardware upon enabling the break condition and sending
543 * a NUL byte.
544 *
545 * Incoming data is corrupted while the break condition is being simulated.
546 *
547 * Normally the duration of the break condition can be controlled individually
548 * by userspace using TIOCSBRK and TIOCCBRK or by passing an argument to
549 * TCSBRKP. Due to how the simulation is implemented the duration can't be
550 * controlled. The duration is always about (1s / 46bd * 9bit) = 196ms.
551 */
552static void ch341_simulate_break(struct tty_struct *tty, int break_state)
553{
554 struct usb_serial_port *port = tty->driver_data;
555 struct ch341_private *priv = usb_get_serial_port_data(port);
556 unsigned long now, delay;
557 int r;
558
559 if (break_state != 0) {
560 dev_dbg(&port->dev, "enter break state requested\n");
561
562 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
563 CH341_MIN_BPS,
564 CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8);
565 if (r < 0) {
566 dev_err(&port->dev,
567 "failed to change baud rate to %u: %d\n",
568 CH341_MIN_BPS, r);
569 goto restore;
570 }
571
572 r = tty_put_char(tty, '\0');
573 if (r < 0) {
574 dev_err(&port->dev,
575 "failed to write NUL byte for simulated break condition: %d\n",
576 r);
577 goto restore;
578 }
579
580 /*
581 * Compute expected transmission duration including safety
582 * margin. The original baud rate is only restored after the
583 * computed point in time.
584 *
585 * 11 bits = 1 start, 8 data, 1 stop, 1 margin
586 */
587 priv->break_end = jiffies + (11 * HZ / CH341_MIN_BPS);
588
589 return;
590 }
591
592 dev_dbg(&port->dev, "leave break state requested\n");
593
594 now = jiffies;
595
596 if (time_before(now, priv->break_end)) {
597 /* Wait until NUL byte is written */
598 delay = priv->break_end - now;
599 dev_dbg(&port->dev,
600 "wait %d ms while transmitting NUL byte at %u baud\n",
601 jiffies_to_msecs(delay), CH341_MIN_BPS);
602 schedule_timeout_interruptible(delay);
603 }
604
605restore:
606 /* Restore original baud rate */
607 r = ch341_set_baudrate_lcr(port->serial->dev, priv, priv->baud_rate,
608 priv->lcr);
609 if (r < 0)
610 dev_err(&port->dev,
611 "restoring original baud rate of %u failed: %d\n",
612 priv->baud_rate, r);
613}
614
615static void ch341_break_ctl(struct tty_struct *tty, int break_state)
616{
617 const uint16_t ch341_break_reg =
618 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
619 struct usb_serial_port *port = tty->driver_data;
620 struct ch341_private *priv = usb_get_serial_port_data(port);
621 int r;
622 uint16_t reg_contents;
623 uint8_t break_reg[2];
624
625 if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK) {
626 ch341_simulate_break(tty, break_state);
627 return;
628 }
629
630 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
631 ch341_break_reg, 0, break_reg, 2);
632 if (r) {
633 dev_err(&port->dev, "%s - USB control read error (%d)\n",
634 __func__, r);
635 return;
636 }
637 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
638 __func__, break_reg[0], break_reg[1]);
639 if (break_state != 0) {
640 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
641 break_reg[0] &= ~CH341_NBREAK_BITS;
642 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
643 } else {
644 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
645 break_reg[0] |= CH341_NBREAK_BITS;
646 break_reg[1] |= CH341_LCR_ENABLE_TX;
647 }
648 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
649 __func__, break_reg[0], break_reg[1]);
650 reg_contents = get_unaligned_le16(break_reg);
651 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
652 ch341_break_reg, reg_contents);
653 if (r < 0)
654 dev_err(&port->dev, "%s - USB control write error (%d)\n",
655 __func__, r);
656}
657
658static int ch341_tiocmset(struct tty_struct *tty,
659 unsigned int set, unsigned int clear)
660{
661 struct usb_serial_port *port = tty->driver_data;
662 struct ch341_private *priv = usb_get_serial_port_data(port);
663 unsigned long flags;
664 u8 control;
665
666 spin_lock_irqsave(&priv->lock, flags);
667 if (set & TIOCM_RTS)
668 priv->mcr |= CH341_BIT_RTS;
669 if (set & TIOCM_DTR)
670 priv->mcr |= CH341_BIT_DTR;
671 if (clear & TIOCM_RTS)
672 priv->mcr &= ~CH341_BIT_RTS;
673 if (clear & TIOCM_DTR)
674 priv->mcr &= ~CH341_BIT_DTR;
675 control = priv->mcr;
676 spin_unlock_irqrestore(&priv->lock, flags);
677
678 return ch341_set_handshake(port->serial->dev, control);
679}
680
681static void ch341_update_status(struct usb_serial_port *port,
682 unsigned char *data, size_t len)
683{
684 struct ch341_private *priv = usb_get_serial_port_data(port);
685 struct tty_struct *tty;
686 unsigned long flags;
687 u8 status;
688 u8 delta;
689
690 if (len < 4)
691 return;
692
693 status = ~data[2] & CH341_BITS_MODEM_STAT;
694
695 spin_lock_irqsave(&priv->lock, flags);
696 delta = status ^ priv->msr;
697 priv->msr = status;
698 spin_unlock_irqrestore(&priv->lock, flags);
699
700 if (data[1] & CH341_MULT_STAT)
701 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
702
703 if (!delta)
704 return;
705
706 if (delta & CH341_BIT_CTS)
707 port->icount.cts++;
708 if (delta & CH341_BIT_DSR)
709 port->icount.dsr++;
710 if (delta & CH341_BIT_RI)
711 port->icount.rng++;
712 if (delta & CH341_BIT_DCD) {
713 port->icount.dcd++;
714 tty = tty_port_tty_get(&port->port);
715 if (tty) {
716 usb_serial_handle_dcd_change(port, tty,
717 status & CH341_BIT_DCD);
718 tty_kref_put(tty);
719 }
720 }
721
722 wake_up_interruptible(&port->port.delta_msr_wait);
723}
724
725static void ch341_read_int_callback(struct urb *urb)
726{
727 struct usb_serial_port *port = urb->context;
728 unsigned char *data = urb->transfer_buffer;
729 unsigned int len = urb->actual_length;
730 int status;
731
732 switch (urb->status) {
733 case 0:
734 /* success */
735 break;
736 case -ECONNRESET:
737 case -ENOENT:
738 case -ESHUTDOWN:
739 /* this urb is terminated, clean up */
740 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
741 __func__, urb->status);
742 return;
743 default:
744 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
745 __func__, urb->status);
746 goto exit;
747 }
748
749 usb_serial_debug_data(&port->dev, __func__, len, data);
750 ch341_update_status(port, data, len);
751exit:
752 status = usb_submit_urb(urb, GFP_ATOMIC);
753 if (status) {
754 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
755 __func__, status);
756 }
757}
758
759static int ch341_tiocmget(struct tty_struct *tty)
760{
761 struct usb_serial_port *port = tty->driver_data;
762 struct ch341_private *priv = usb_get_serial_port_data(port);
763 unsigned long flags;
764 u8 mcr;
765 u8 status;
766 unsigned int result;
767
768 spin_lock_irqsave(&priv->lock, flags);
769 mcr = priv->mcr;
770 status = priv->msr;
771 spin_unlock_irqrestore(&priv->lock, flags);
772
773 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
774 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
775 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
776 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
777 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
778 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
779
780 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
781
782 return result;
783}
784
785static int ch341_reset_resume(struct usb_serial *serial)
786{
787 struct usb_serial_port *port = serial->port[0];
788 struct ch341_private *priv;
789 int ret;
790
791 priv = usb_get_serial_port_data(port);
792 if (!priv)
793 return 0;
794
795 /* reconfigure ch341 serial port after bus-reset */
796 ch341_configure(serial->dev, priv);
797
798 if (tty_port_initialized(&port->port)) {
799 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
800 if (ret) {
801 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
802 ret);
803 return ret;
804 }
805
806 ret = ch341_get_status(port->serial->dev, priv);
807 if (ret < 0) {
808 dev_err(&port->dev, "failed to read modem status: %d\n",
809 ret);
810 }
811 }
812
813 return usb_serial_generic_resume(serial);
814}
815
816static struct usb_serial_driver ch341_device = {
817 .driver = {
818 .owner = THIS_MODULE,
819 .name = "ch341-uart",
820 },
821 .id_table = id_table,
822 .num_ports = 1,
823 .open = ch341_open,
824 .dtr_rts = ch341_dtr_rts,
825 .carrier_raised = ch341_carrier_raised,
826 .close = ch341_close,
827 .set_termios = ch341_set_termios,
828 .break_ctl = ch341_break_ctl,
829 .tiocmget = ch341_tiocmget,
830 .tiocmset = ch341_tiocmset,
831 .tiocmiwait = usb_serial_generic_tiocmiwait,
832 .read_int_callback = ch341_read_int_callback,
833 .port_probe = ch341_port_probe,
834 .port_remove = ch341_port_remove,
835 .reset_resume = ch341_reset_resume,
836};
837
838static struct usb_serial_driver * const serial_drivers[] = {
839 &ch341_device, NULL
840};
841
842module_usb_serial_driver(serial_drivers, id_table);
843
844MODULE_LICENSE("GPL v2");
845

source code of linux/drivers/usb/serial/ch341.c