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 <linux/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#define CH341_REG_FLOW_CTL 0x27
67
68#define CH341_NBREAK_BITS 0x01
69
70#define CH341_LCR_ENABLE_RX 0x80
71#define CH341_LCR_ENABLE_TX 0x40
72#define CH341_LCR_MARK_SPACE 0x20
73#define CH341_LCR_PAR_EVEN 0x10
74#define CH341_LCR_ENABLE_PAR 0x08
75#define CH341_LCR_STOP_BITS_2 0x04
76#define CH341_LCR_CS8 0x03
77#define CH341_LCR_CS7 0x02
78#define CH341_LCR_CS6 0x01
79#define CH341_LCR_CS5 0x00
80
81#define CH341_FLOW_CTL_NONE 0x00
82#define CH341_FLOW_CTL_RTSCTS 0x01
83
84#define CH341_QUIRK_LIMITED_PRESCALER BIT(0)
85#define CH341_QUIRK_SIMULATE_BREAK BIT(1)
86
87static const struct usb_device_id id_table[] = {
88 { USB_DEVICE(0x1a86, 0x5523) },
89 { USB_DEVICE(0x1a86, 0x7522) },
90 { USB_DEVICE(0x1a86, 0x7523) },
91 { USB_DEVICE(0x2184, 0x0057) },
92 { USB_DEVICE(0x4348, 0x5523) },
93 { USB_DEVICE(0x9986, 0x7523) },
94 { },
95};
96MODULE_DEVICE_TABLE(usb, id_table);
97
98struct ch341_private {
99 spinlock_t lock; /* access lock */
100 unsigned baud_rate; /* set baud rate */
101 u8 mcr;
102 u8 msr;
103 u8 lcr;
104
105 unsigned long quirks;
106 u8 version;
107
108 unsigned long break_end;
109};
110
111static void ch341_set_termios(struct tty_struct *tty,
112 struct usb_serial_port *port,
113 const struct ktermios *old_termios);
114
115static int ch341_control_out(struct usb_device *dev, u8 request,
116 u16 value, u16 index)
117{
118 int r;
119
120 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
121 request, value, index);
122
123 r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
124 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
125 value, index, NULL, size: 0, DEFAULT_TIMEOUT);
126 if (r < 0)
127 dev_err(&dev->dev, "failed to send control message: %d\n", r);
128
129 return r;
130}
131
132static int ch341_control_in(struct usb_device *dev,
133 u8 request, u16 value, u16 index,
134 char *buf, unsigned bufsize)
135{
136 int r;
137
138 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
139 request, value, index, bufsize);
140
141 r = usb_control_msg_recv(dev, endpoint: 0, request,
142 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
143 value, index, data: buf, size: bufsize, DEFAULT_TIMEOUT,
144 GFP_KERNEL);
145 if (r) {
146 dev_err(&dev->dev, "failed to receive control message: %d\n",
147 r);
148 return r;
149 }
150
151 return 0;
152}
153
154#define CH341_CLKRATE 48000000
155#define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
156#define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
157
158static const speed_t ch341_min_rates[] = {
159 CH341_MIN_RATE(0),
160 CH341_MIN_RATE(1),
161 CH341_MIN_RATE(2),
162 CH341_MIN_RATE(3),
163};
164
165/* Supported range is 46 to 3000000 bps. */
166#define CH341_MIN_BPS DIV_ROUND_UP(CH341_CLKRATE, CH341_CLK_DIV(0, 0) * 256)
167#define CH341_MAX_BPS (CH341_CLKRATE / (CH341_CLK_DIV(3, 0) * 2))
168
169/*
170 * The device line speed is given by the following equation:
171 *
172 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
173 *
174 * 0 <= ps <= 3,
175 * 0 <= fact <= 1,
176 * 2 <= div <= 256 if fact = 0, or
177 * 9 <= div <= 256 if fact = 1
178 */
179static int ch341_get_divisor(struct ch341_private *priv, speed_t speed)
180{
181 unsigned int fact, div, clk_div;
182 bool force_fact0 = false;
183 int ps;
184
185 /*
186 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
187 * sanity checks below redundant.
188 */
189 speed = clamp_val(speed, CH341_MIN_BPS, CH341_MAX_BPS);
190
191 /*
192 * Start with highest possible base clock (fact = 1) that will give a
193 * divisor strictly less than 512.
194 */
195 fact = 1;
196 for (ps = 3; ps >= 0; ps--) {
197 if (speed > ch341_min_rates[ps])
198 break;
199 }
200
201 if (ps < 0)
202 return -EINVAL;
203
204 /* Determine corresponding divisor, rounding down. */
205 clk_div = CH341_CLK_DIV(ps, fact);
206 div = CH341_CLKRATE / (clk_div * speed);
207
208 /* Some devices require a lower base clock if ps < 3. */
209 if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER))
210 force_fact0 = true;
211
212 /* Halve base clock (fact = 0) if required. */
213 if (div < 9 || div > 255 || force_fact0) {
214 div /= 2;
215 clk_div *= 2;
216 fact = 0;
217 }
218
219 if (div < 2)
220 return -EINVAL;
221
222 /*
223 * Pick next divisor if resulting rate is closer to the requested one,
224 * scale up to avoid rounding errors on low rates.
225 */
226 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
227 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
228 div++;
229
230 /*
231 * Prefer lower base clock (fact = 0) if even divisor.
232 *
233 * Note that this makes the receiver more tolerant to errors.
234 */
235 if (fact == 1 && div % 2 == 0) {
236 div /= 2;
237 fact = 0;
238 }
239
240 return (0x100 - div) << 8 | fact << 2 | ps;
241}
242
243static int ch341_set_baudrate_lcr(struct usb_device *dev,
244 struct ch341_private *priv,
245 speed_t baud_rate, u8 lcr)
246{
247 int val;
248 int r;
249
250 if (!baud_rate)
251 return -EINVAL;
252
253 val = ch341_get_divisor(priv, speed: baud_rate);
254 if (val < 0)
255 return -EINVAL;
256
257 /*
258 * CH341A buffers data until a full endpoint-size packet (32 bytes)
259 * has been received unless bit 7 is set.
260 *
261 * At least one device with version 0x27 appears to have this bit
262 * inverted.
263 */
264 if (priv->version > 0x27)
265 val |= BIT(7);
266
267 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
268 CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
269 index: val);
270 if (r)
271 return r;
272
273 /*
274 * Chip versions before version 0x30 as read using
275 * CH341_REQ_READ_VERSION used separate registers for line control
276 * (stop bits, parity and word length). Version 0x30 and above use
277 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
278 */
279 if (priv->version < 0x30)
280 return 0;
281
282 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
283 CH341_REG_LCR2 << 8 | CH341_REG_LCR, index: lcr);
284 if (r)
285 return r;
286
287 return r;
288}
289
290static int ch341_set_handshake(struct usb_device *dev, u8 control)
291{
292 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, value: ~control, index: 0);
293}
294
295static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
296{
297 const unsigned int size = 2;
298 u8 buffer[2];
299 int r;
300 unsigned long flags;
301
302 r = ch341_control_in(dev, CH341_REQ_READ_REG, value: 0x0706, index: 0, buf: buffer, bufsize: size);
303 if (r)
304 return r;
305
306 spin_lock_irqsave(&priv->lock, flags);
307 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
308 spin_unlock_irqrestore(lock: &priv->lock, flags);
309
310 return 0;
311}
312
313/* -------------------------------------------------------------------------- */
314
315static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
316{
317 const unsigned int size = 2;
318 u8 buffer[2];
319 int r;
320
321 /* expect two bytes 0x27 0x00 */
322 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, value: 0, index: 0, buf: buffer, bufsize: size);
323 if (r)
324 return r;
325
326 priv->version = buffer[0];
327 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", priv->version);
328
329 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, value: 0, index: 0);
330 if (r < 0)
331 return r;
332
333 r = ch341_set_baudrate_lcr(dev, priv, baud_rate: priv->baud_rate, lcr: priv->lcr);
334 if (r < 0)
335 return r;
336
337 r = ch341_set_handshake(dev, control: priv->mcr);
338 if (r < 0)
339 return r;
340
341 return 0;
342}
343
344static int ch341_detect_quirks(struct usb_serial_port *port)
345{
346 struct ch341_private *priv = usb_get_serial_port_data(port);
347 struct usb_device *udev = port->serial->dev;
348 const unsigned int size = 2;
349 unsigned long quirks = 0;
350 u8 buffer[2];
351 int r;
352
353 /*
354 * A subset of CH34x devices does not support all features. The
355 * prescaler is limited and there is no support for sending a RS232
356 * break condition. A read failure when trying to set up the latter is
357 * used to detect these devices.
358 */
359 r = usb_control_msg_recv(dev: udev, endpoint: 0, CH341_REQ_READ_REG,
360 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
361 CH341_REG_BREAK, index: 0, data: &buffer, size,
362 DEFAULT_TIMEOUT, GFP_KERNEL);
363 if (r == -EPIPE) {
364 dev_info(&port->dev, "break control not supported, using simulated break\n");
365 quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK;
366 r = 0;
367 } else if (r) {
368 dev_err(&port->dev, "failed to read break control: %d\n", r);
369 }
370
371 if (quirks) {
372 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
373 priv->quirks |= quirks;
374 }
375
376 return r;
377}
378
379static int ch341_port_probe(struct usb_serial_port *port)
380{
381 struct ch341_private *priv;
382 int r;
383
384 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
385 if (!priv)
386 return -ENOMEM;
387
388 spin_lock_init(&priv->lock);
389 priv->baud_rate = DEFAULT_BAUD_RATE;
390 /*
391 * Some CH340 devices appear unable to change the initial LCR
392 * settings, so set a sane 8N1 default.
393 */
394 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
395
396 r = ch341_configure(dev: port->serial->dev, priv);
397 if (r < 0)
398 goto error;
399
400 usb_set_serial_port_data(port, data: priv);
401
402 r = ch341_detect_quirks(port);
403 if (r < 0)
404 goto error;
405
406 return 0;
407
408error: kfree(objp: priv);
409 return r;
410}
411
412static void ch341_port_remove(struct usb_serial_port *port)
413{
414 struct ch341_private *priv;
415
416 priv = usb_get_serial_port_data(port);
417 kfree(objp: priv);
418}
419
420static int ch341_carrier_raised(struct usb_serial_port *port)
421{
422 struct ch341_private *priv = usb_get_serial_port_data(port);
423 if (priv->msr & CH341_BIT_DCD)
424 return 1;
425 return 0;
426}
427
428static void ch341_dtr_rts(struct usb_serial_port *port, int on)
429{
430 struct ch341_private *priv = usb_get_serial_port_data(port);
431 unsigned long flags;
432
433 /* drop DTR and RTS */
434 spin_lock_irqsave(&priv->lock, flags);
435 if (on)
436 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
437 else
438 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
439 spin_unlock_irqrestore(lock: &priv->lock, flags);
440 ch341_set_handshake(dev: port->serial->dev, control: priv->mcr);
441}
442
443static void ch341_close(struct usb_serial_port *port)
444{
445 usb_serial_generic_close(port);
446 usb_kill_urb(urb: port->interrupt_in_urb);
447}
448
449
450/* open this device, set default parameters */
451static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
452{
453 struct ch341_private *priv = usb_get_serial_port_data(port);
454 int r;
455
456 if (tty)
457 ch341_set_termios(tty, port, NULL);
458
459 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
460 r = usb_submit_urb(urb: port->interrupt_in_urb, GFP_KERNEL);
461 if (r) {
462 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
463 __func__, r);
464 return r;
465 }
466
467 r = ch341_get_status(dev: port->serial->dev, priv);
468 if (r < 0) {
469 dev_err(&port->dev, "failed to read modem status: %d\n", r);
470 goto err_kill_interrupt_urb;
471 }
472
473 r = usb_serial_generic_open(tty, port);
474 if (r)
475 goto err_kill_interrupt_urb;
476
477 return 0;
478
479err_kill_interrupt_urb:
480 usb_kill_urb(urb: port->interrupt_in_urb);
481
482 return r;
483}
484
485static void ch341_set_flow_control(struct tty_struct *tty,
486 struct usb_serial_port *port,
487 const struct ktermios *old_termios)
488{
489 u16 flow_ctl;
490 int r;
491
492 if (C_CRTSCTS(tty))
493 flow_ctl = CH341_FLOW_CTL_RTSCTS;
494 else
495 flow_ctl = CH341_FLOW_CTL_NONE;
496
497 r = ch341_control_out(dev: port->serial->dev,
498 CH341_REQ_WRITE_REG,
499 value: (CH341_REG_FLOW_CTL << 8) | CH341_REG_FLOW_CTL,
500 index: (flow_ctl << 8) | flow_ctl);
501 if (r < 0 && old_termios) {
502 tty->termios.c_cflag &= ~CRTSCTS;
503 tty->termios.c_cflag |= (old_termios->c_cflag & CRTSCTS);
504 }
505}
506
507/* Old_termios contains the original termios settings and
508 * tty->termios contains the new setting to be used.
509 */
510static void ch341_set_termios(struct tty_struct *tty,
511 struct usb_serial_port *port,
512 const struct ktermios *old_termios)
513{
514 struct ch341_private *priv = usb_get_serial_port_data(port);
515 unsigned baud_rate;
516 unsigned long flags;
517 u8 lcr;
518 int r;
519
520 /* redundant changes may cause the chip to lose bytes */
521 if (old_termios && !tty_termios_hw_change(a: &tty->termios, b: old_termios))
522 return;
523
524 baud_rate = tty_get_baud_rate(tty);
525
526 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
527
528 switch (C_CSIZE(tty)) {
529 case CS5:
530 lcr |= CH341_LCR_CS5;
531 break;
532 case CS6:
533 lcr |= CH341_LCR_CS6;
534 break;
535 case CS7:
536 lcr |= CH341_LCR_CS7;
537 break;
538 case CS8:
539 lcr |= CH341_LCR_CS8;
540 break;
541 }
542
543 if (C_PARENB(tty)) {
544 lcr |= CH341_LCR_ENABLE_PAR;
545 if (C_PARODD(tty) == 0)
546 lcr |= CH341_LCR_PAR_EVEN;
547 if (C_CMSPAR(tty))
548 lcr |= CH341_LCR_MARK_SPACE;
549 }
550
551 if (C_CSTOPB(tty))
552 lcr |= CH341_LCR_STOP_BITS_2;
553
554 if (baud_rate) {
555 priv->baud_rate = baud_rate;
556
557 r = ch341_set_baudrate_lcr(dev: port->serial->dev, priv,
558 baud_rate: priv->baud_rate, lcr);
559 if (r < 0 && old_termios) {
560 priv->baud_rate = tty_termios_baud_rate(termios: old_termios);
561 tty_termios_copy_hw(new: &tty->termios, old: old_termios);
562 } else if (r == 0) {
563 priv->lcr = lcr;
564 }
565 }
566
567 spin_lock_irqsave(&priv->lock, flags);
568 if (C_BAUD(tty) == B0)
569 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
570 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
571 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
572 spin_unlock_irqrestore(lock: &priv->lock, flags);
573
574 ch341_set_handshake(dev: port->serial->dev, control: priv->mcr);
575
576 ch341_set_flow_control(tty, port, old_termios);
577}
578
579/*
580 * A subset of all CH34x devices don't support a real break condition and
581 * reading CH341_REG_BREAK fails (see also ch341_detect_quirks). This function
582 * simulates a break condition by lowering the baud rate to the minimum
583 * supported by the hardware upon enabling the break condition and sending
584 * a NUL byte.
585 *
586 * Incoming data is corrupted while the break condition is being simulated.
587 *
588 * Normally the duration of the break condition can be controlled individually
589 * by userspace using TIOCSBRK and TIOCCBRK or by passing an argument to
590 * TCSBRKP. Due to how the simulation is implemented the duration can't be
591 * controlled. The duration is always about (1s / 46bd * 9bit) = 196ms.
592 */
593static int ch341_simulate_break(struct tty_struct *tty, int break_state)
594{
595 struct usb_serial_port *port = tty->driver_data;
596 struct ch341_private *priv = usb_get_serial_port_data(port);
597 unsigned long now, delay;
598 int r, r2;
599
600 if (break_state != 0) {
601 dev_dbg(&port->dev, "enter break state requested\n");
602
603 r = ch341_set_baudrate_lcr(dev: port->serial->dev, priv,
604 CH341_MIN_BPS,
605 CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8);
606 if (r < 0) {
607 dev_err(&port->dev,
608 "failed to change baud rate to %u: %d\n",
609 CH341_MIN_BPS, r);
610 goto restore;
611 }
612
613 r = tty_put_char(tty, c: '\0');
614 if (r < 0) {
615 dev_err(&port->dev,
616 "failed to write NUL byte for simulated break condition: %d\n",
617 r);
618 goto restore;
619 }
620
621 /*
622 * Compute expected transmission duration including safety
623 * margin. The original baud rate is only restored after the
624 * computed point in time.
625 *
626 * 11 bits = 1 start, 8 data, 1 stop, 1 margin
627 */
628 priv->break_end = jiffies + (11 * HZ / CH341_MIN_BPS);
629
630 return 0;
631 }
632
633 dev_dbg(&port->dev, "leave break state requested\n");
634
635 now = jiffies;
636
637 if (time_before(now, priv->break_end)) {
638 /* Wait until NUL byte is written */
639 delay = priv->break_end - now;
640 dev_dbg(&port->dev,
641 "wait %d ms while transmitting NUL byte at %u baud\n",
642 jiffies_to_msecs(delay), CH341_MIN_BPS);
643 schedule_timeout_interruptible(timeout: delay);
644 }
645
646 r = 0;
647restore:
648 /* Restore original baud rate */
649 r2 = ch341_set_baudrate_lcr(dev: port->serial->dev, priv, baud_rate: priv->baud_rate,
650 lcr: priv->lcr);
651 if (r2 < 0) {
652 dev_err(&port->dev,
653 "restoring original baud rate of %u failed: %d\n",
654 priv->baud_rate, r2);
655 return r2;
656 }
657
658 return r;
659}
660
661static int ch341_break_ctl(struct tty_struct *tty, int break_state)
662{
663 const u16 ch341_break_reg = (CH341_REG_LCR << 8) | CH341_REG_BREAK;
664 struct usb_serial_port *port = tty->driver_data;
665 struct ch341_private *priv = usb_get_serial_port_data(port);
666 u16 reg_contents;
667 u8 break_reg[2];
668 int r;
669
670 if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK)
671 return ch341_simulate_break(tty, break_state);
672
673 r = ch341_control_in(dev: port->serial->dev, CH341_REQ_READ_REG,
674 value: ch341_break_reg, index: 0, buf: break_reg, bufsize: 2);
675 if (r) {
676 dev_err(&port->dev, "%s - USB control read error (%d)\n",
677 __func__, r);
678 if (r > 0)
679 r = -EIO;
680 return r;
681 }
682 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
683 __func__, break_reg[0], break_reg[1]);
684 if (break_state != 0) {
685 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
686 break_reg[0] &= ~CH341_NBREAK_BITS;
687 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
688 } else {
689 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
690 break_reg[0] |= CH341_NBREAK_BITS;
691 break_reg[1] |= CH341_LCR_ENABLE_TX;
692 }
693 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
694 __func__, break_reg[0], break_reg[1]);
695 reg_contents = get_unaligned_le16(p: break_reg);
696 r = ch341_control_out(dev: port->serial->dev, CH341_REQ_WRITE_REG,
697 value: ch341_break_reg, index: reg_contents);
698 if (r < 0) {
699 dev_err(&port->dev, "%s - USB control write error (%d)\n",
700 __func__, r);
701 return r;
702 }
703
704 return 0;
705}
706
707static int ch341_tiocmset(struct tty_struct *tty,
708 unsigned int set, unsigned int clear)
709{
710 struct usb_serial_port *port = tty->driver_data;
711 struct ch341_private *priv = usb_get_serial_port_data(port);
712 unsigned long flags;
713 u8 control;
714
715 spin_lock_irqsave(&priv->lock, flags);
716 if (set & TIOCM_RTS)
717 priv->mcr |= CH341_BIT_RTS;
718 if (set & TIOCM_DTR)
719 priv->mcr |= CH341_BIT_DTR;
720 if (clear & TIOCM_RTS)
721 priv->mcr &= ~CH341_BIT_RTS;
722 if (clear & TIOCM_DTR)
723 priv->mcr &= ~CH341_BIT_DTR;
724 control = priv->mcr;
725 spin_unlock_irqrestore(lock: &priv->lock, flags);
726
727 return ch341_set_handshake(dev: port->serial->dev, control);
728}
729
730static void ch341_update_status(struct usb_serial_port *port,
731 unsigned char *data, size_t len)
732{
733 struct ch341_private *priv = usb_get_serial_port_data(port);
734 struct tty_struct *tty;
735 unsigned long flags;
736 u8 status;
737 u8 delta;
738
739 if (len < 4)
740 return;
741
742 status = ~data[2] & CH341_BITS_MODEM_STAT;
743
744 spin_lock_irqsave(&priv->lock, flags);
745 delta = status ^ priv->msr;
746 priv->msr = status;
747 spin_unlock_irqrestore(lock: &priv->lock, flags);
748
749 if (data[1] & CH341_MULT_STAT)
750 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
751
752 if (!delta)
753 return;
754
755 if (delta & CH341_BIT_CTS)
756 port->icount.cts++;
757 if (delta & CH341_BIT_DSR)
758 port->icount.dsr++;
759 if (delta & CH341_BIT_RI)
760 port->icount.rng++;
761 if (delta & CH341_BIT_DCD) {
762 port->icount.dcd++;
763 tty = tty_port_tty_get(port: &port->port);
764 if (tty) {
765 usb_serial_handle_dcd_change(usb_port: port, tty,
766 status: status & CH341_BIT_DCD);
767 tty_kref_put(tty);
768 }
769 }
770
771 wake_up_interruptible(&port->port.delta_msr_wait);
772}
773
774static void ch341_read_int_callback(struct urb *urb)
775{
776 struct usb_serial_port *port = urb->context;
777 unsigned char *data = urb->transfer_buffer;
778 unsigned int len = urb->actual_length;
779 int status;
780
781 switch (urb->status) {
782 case 0:
783 /* success */
784 break;
785 case -ECONNRESET:
786 case -ENOENT:
787 case -ESHUTDOWN:
788 /* this urb is terminated, clean up */
789 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
790 __func__, urb->status);
791 return;
792 default:
793 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
794 __func__, urb->status);
795 goto exit;
796 }
797
798 usb_serial_debug_data(dev: &port->dev, function: __func__, size: len, data);
799 ch341_update_status(port, data, len);
800exit:
801 status = usb_submit_urb(urb, GFP_ATOMIC);
802 if (status) {
803 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
804 __func__, status);
805 }
806}
807
808static int ch341_tiocmget(struct tty_struct *tty)
809{
810 struct usb_serial_port *port = tty->driver_data;
811 struct ch341_private *priv = usb_get_serial_port_data(port);
812 unsigned long flags;
813 u8 mcr;
814 u8 status;
815 unsigned int result;
816
817 spin_lock_irqsave(&priv->lock, flags);
818 mcr = priv->mcr;
819 status = priv->msr;
820 spin_unlock_irqrestore(lock: &priv->lock, flags);
821
822 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
823 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
824 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
825 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
826 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
827 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
828
829 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
830
831 return result;
832}
833
834static int ch341_reset_resume(struct usb_serial *serial)
835{
836 struct usb_serial_port *port = serial->port[0];
837 struct ch341_private *priv;
838 int ret;
839
840 priv = usb_get_serial_port_data(port);
841 if (!priv)
842 return 0;
843
844 /* reconfigure ch341 serial port after bus-reset */
845 ch341_configure(dev: serial->dev, priv);
846
847 if (tty_port_initialized(port: &port->port)) {
848 ret = usb_submit_urb(urb: port->interrupt_in_urb, GFP_NOIO);
849 if (ret) {
850 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
851 ret);
852 return ret;
853 }
854
855 ret = ch341_get_status(dev: port->serial->dev, priv);
856 if (ret < 0) {
857 dev_err(&port->dev, "failed to read modem status: %d\n",
858 ret);
859 }
860 }
861
862 return usb_serial_generic_resume(serial);
863}
864
865static struct usb_serial_driver ch341_device = {
866 .driver = {
867 .name = "ch341-uart",
868 },
869 .id_table = id_table,
870 .num_ports = 1,
871 .open = ch341_open,
872 .dtr_rts = ch341_dtr_rts,
873 .carrier_raised = ch341_carrier_raised,
874 .close = ch341_close,
875 .set_termios = ch341_set_termios,
876 .break_ctl = ch341_break_ctl,
877 .tiocmget = ch341_tiocmget,
878 .tiocmset = ch341_tiocmset,
879 .tiocmiwait = usb_serial_generic_tiocmiwait,
880 .read_int_callback = ch341_read_int_callback,
881 .port_probe = ch341_port_probe,
882 .port_remove = ch341_port_remove,
883 .reset_resume = ch341_reset_resume,
884};
885
886static struct usb_serial_driver * const serial_drivers[] = {
887 &ch341_device, NULL
888};
889
890module_usb_serial_driver(serial_drivers, id_table);
891
892MODULE_DESCRIPTION("Winchiphead CH341 USB Serial driver");
893MODULE_LICENSE("GPL v2");
894

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