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
83 static const struct usb_device_id id_table[] = {
84 { USB_DEVICE(0x1a86, 0x5512) },
85 { USB_DEVICE(0x1a86, 0x5523) },
86 { USB_DEVICE(0x1a86, 0x7522) },
87 { USB_DEVICE(0x1a86, 0x7523) },
88 { USB_DEVICE(0x4348, 0x5523) },
89 { USB_DEVICE(0x9986, 0x7523) },
90 { },
91 };
92 MODULE_DEVICE_TABLE(usb, id_table);
93
94 struct 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
104 static void ch341_set_termios(struct tty_struct *tty,
105 struct usb_serial_port *port,
106 struct ktermios *old_termios);
107
ch341_control_out(struct usb_device * dev,u8 request,u16 value,u16 index)108 static 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
ch341_control_in(struct usb_device * dev,u8 request,u16 value,u16 index,char * buf,unsigned bufsize)125 static 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(dev, usb_rcvctrlpipe(dev, 0), request,
135 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
136 value, index, buf, bufsize, DEFAULT_TIMEOUT);
137 if (r < (int)bufsize) {
138 if (r >= 0) {
139 dev_err(&dev->dev,
140 "short control message received (%d < %u)\n",
141 r, bufsize);
142 r = -EIO;
143 }
144
145 dev_err(&dev->dev, "failed to receive control message: %d\n",
146 r);
147 return r;
148 }
149
150 return 0;
151 }
152
153 #define CH341_CLKRATE 48000000
154 #define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
155 #define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
156
157 static const speed_t ch341_min_rates[] = {
158 CH341_MIN_RATE(0),
159 CH341_MIN_RATE(1),
160 CH341_MIN_RATE(2),
161 CH341_MIN_RATE(3),
162 };
163
164 /* Supported range is 46 to 3000000 bps. */
165 #define CH341_MIN_BPS DIV_ROUND_UP(CH341_CLKRATE, CH341_CLK_DIV(0, 0) * 256)
166 #define CH341_MAX_BPS (CH341_CLKRATE / (CH341_CLK_DIV(3, 0) * 2))
167
168 /*
169 * The device line speed is given by the following equation:
170 *
171 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
172 *
173 * 0 <= ps <= 3,
174 * 0 <= fact <= 1,
175 * 2 <= div <= 256 if fact = 0, or
176 * 9 <= div <= 256 if fact = 1
177 */
ch341_get_divisor(struct ch341_private * priv,speed_t speed)178 static int ch341_get_divisor(struct ch341_private *priv, speed_t speed)
179 {
180 unsigned int fact, div, clk_div;
181 bool force_fact0 = false;
182 int ps;
183
184 /*
185 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
186 * sanity checks below redundant.
187 */
188 speed = clamp_val(speed, CH341_MIN_BPS, CH341_MAX_BPS);
189
190 /*
191 * Start with highest possible base clock (fact = 1) that will give a
192 * divisor strictly less than 512.
193 */
194 fact = 1;
195 for (ps = 3; ps >= 0; ps--) {
196 if (speed > ch341_min_rates[ps])
197 break;
198 }
199
200 if (ps < 0)
201 return -EINVAL;
202
203 /* Determine corresponding divisor, rounding down. */
204 clk_div = CH341_CLK_DIV(ps, fact);
205 div = CH341_CLKRATE / (clk_div * speed);
206
207 /* Some devices require a lower base clock if ps < 3. */
208 if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER))
209 force_fact0 = true;
210
211 /* Halve base clock (fact = 0) if required. */
212 if (div < 9 || div > 255 || force_fact0) {
213 div /= 2;
214 clk_div *= 2;
215 fact = 0;
216 }
217
218 if (div < 2)
219 return -EINVAL;
220
221 /*
222 * Pick next divisor if resulting rate is closer to the requested one,
223 * scale up to avoid rounding errors on low rates.
224 */
225 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
226 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
227 div++;
228
229 /*
230 * Prefer lower base clock (fact = 0) if even divisor.
231 *
232 * Note that this makes the receiver more tolerant to errors.
233 */
234 if (fact == 1 && div % 2 == 0) {
235 div /= 2;
236 fact = 0;
237 }
238
239 return (0x100 - div) << 8 | fact << 2 | ps;
240 }
241
ch341_set_baudrate_lcr(struct usb_device * dev,struct ch341_private * priv,speed_t baud_rate,u8 lcr)242 static int ch341_set_baudrate_lcr(struct usb_device *dev,
243 struct ch341_private *priv,
244 speed_t baud_rate, u8 lcr)
245 {
246 int val;
247 int r;
248
249 if (!baud_rate)
250 return -EINVAL;
251
252 val = ch341_get_divisor(priv, baud_rate);
253 if (val < 0)
254 return -EINVAL;
255
256 /*
257 * CH341A buffers data until a full endpoint-size packet (32 bytes)
258 * has been received unless bit 7 is set.
259 */
260 val |= BIT(7);
261
262 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
263 CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
264 val);
265 if (r)
266 return r;
267
268 /*
269 * Chip versions before version 0x30 as read using
270 * CH341_REQ_READ_VERSION used separate registers for line control
271 * (stop bits, parity and word length). Version 0x30 and above use
272 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
273 */
274 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
275 CH341_REG_LCR2 << 8 | CH341_REG_LCR, lcr);
276 if (r)
277 return r;
278
279 return r;
280 }
281
ch341_set_handshake(struct usb_device * dev,u8 control)282 static int ch341_set_handshake(struct usb_device *dev, u8 control)
283 {
284 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
285 }
286
ch341_get_status(struct usb_device * dev,struct ch341_private * priv)287 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
288 {
289 const unsigned int size = 2;
290 char *buffer;
291 int r;
292 unsigned long flags;
293
294 buffer = kmalloc(size, GFP_KERNEL);
295 if (!buffer)
296 return -ENOMEM;
297
298 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
299 if (r < 0)
300 goto out;
301
302 spin_lock_irqsave(&priv->lock, flags);
303 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
304 spin_unlock_irqrestore(&priv->lock, flags);
305
306 out: kfree(buffer);
307 return r;
308 }
309
310 /* -------------------------------------------------------------------------- */
311
ch341_configure(struct usb_device * dev,struct ch341_private * priv)312 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
313 {
314 const unsigned int size = 2;
315 char *buffer;
316 int r;
317
318 buffer = kmalloc(size, GFP_KERNEL);
319 if (!buffer)
320 return -ENOMEM;
321
322 /* expect two bytes 0x27 0x00 */
323 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
324 if (r < 0)
325 goto out;
326 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
327
328 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
329 if (r < 0)
330 goto out;
331
332 r = ch341_set_baudrate_lcr(dev, priv, priv->baud_rate, priv->lcr);
333 if (r < 0)
334 goto out;
335
336 r = ch341_set_handshake(dev, priv->mcr);
337
338 out: kfree(buffer);
339 return r;
340 }
341
ch341_detect_quirks(struct usb_serial_port * port)342 static int ch341_detect_quirks(struct usb_serial_port *port)
343 {
344 struct ch341_private *priv = usb_get_serial_port_data(port);
345 struct usb_device *udev = port->serial->dev;
346 const unsigned int size = 2;
347 unsigned long quirks = 0;
348 char *buffer;
349 int r;
350
351 buffer = kmalloc(size, GFP_KERNEL);
352 if (!buffer)
353 return -ENOMEM;
354
355 /*
356 * A subset of CH34x devices does not support all features. The
357 * prescaler is limited and there is no support for sending a RS232
358 * break condition. A read failure when trying to set up the latter is
359 * used to detect these devices.
360 */
361 r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG,
362 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
363 CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT);
364 if (r == -EPIPE) {
365 dev_info(&port->dev, "break control not supported, using simulated break\n");
366 quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK;
367 r = 0;
368 goto out;
369 }
370
371 if (r != size) {
372 if (r >= 0)
373 r = -EIO;
374 dev_err(&port->dev, "failed to read break control: %d\n", r);
375 goto out;
376 }
377
378 r = 0;
379 out:
380 kfree(buffer);
381
382 if (quirks) {
383 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
384 priv->quirks |= quirks;
385 }
386
387 return r;
388 }
389
ch341_port_probe(struct usb_serial_port * port)390 static int ch341_port_probe(struct usb_serial_port *port)
391 {
392 struct ch341_private *priv;
393 int r;
394
395 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
396 if (!priv)
397 return -ENOMEM;
398
399 spin_lock_init(&priv->lock);
400 priv->baud_rate = DEFAULT_BAUD_RATE;
401 /*
402 * Some CH340 devices appear unable to change the initial LCR
403 * settings, so set a sane 8N1 default.
404 */
405 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
406
407 r = ch341_configure(port->serial->dev, priv);
408 if (r < 0)
409 goto error;
410
411 usb_set_serial_port_data(port, priv);
412
413 r = ch341_detect_quirks(port);
414 if (r < 0)
415 goto error;
416
417 return 0;
418
419 error: kfree(priv);
420 return r;
421 }
422
ch341_port_remove(struct usb_serial_port * port)423 static int ch341_port_remove(struct usb_serial_port *port)
424 {
425 struct ch341_private *priv;
426
427 priv = usb_get_serial_port_data(port);
428 kfree(priv);
429
430 return 0;
431 }
432
ch341_carrier_raised(struct usb_serial_port * port)433 static int ch341_carrier_raised(struct usb_serial_port *port)
434 {
435 struct ch341_private *priv = usb_get_serial_port_data(port);
436 if (priv->msr & CH341_BIT_DCD)
437 return 1;
438 return 0;
439 }
440
ch341_dtr_rts(struct usb_serial_port * port,int on)441 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
442 {
443 struct ch341_private *priv = usb_get_serial_port_data(port);
444 unsigned long flags;
445
446 /* drop DTR and RTS */
447 spin_lock_irqsave(&priv->lock, flags);
448 if (on)
449 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
450 else
451 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
452 spin_unlock_irqrestore(&priv->lock, flags);
453 ch341_set_handshake(port->serial->dev, priv->mcr);
454 }
455
ch341_close(struct usb_serial_port * port)456 static void ch341_close(struct usb_serial_port *port)
457 {
458 usb_serial_generic_close(port);
459 usb_kill_urb(port->interrupt_in_urb);
460 }
461
462
463 /* open this device, set default parameters */
ch341_open(struct tty_struct * tty,struct usb_serial_port * port)464 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
465 {
466 struct ch341_private *priv = usb_get_serial_port_data(port);
467 int r;
468
469 if (tty)
470 ch341_set_termios(tty, port, NULL);
471
472 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
473 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
474 if (r) {
475 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
476 __func__, r);
477 return r;
478 }
479
480 r = ch341_get_status(port->serial->dev, priv);
481 if (r < 0) {
482 dev_err(&port->dev, "failed to read modem status: %d\n", r);
483 goto err_kill_interrupt_urb;
484 }
485
486 r = usb_serial_generic_open(tty, port);
487 if (r)
488 goto err_kill_interrupt_urb;
489
490 return 0;
491
492 err_kill_interrupt_urb:
493 usb_kill_urb(port->interrupt_in_urb);
494
495 return r;
496 }
497
498 /* Old_termios contains the original termios settings and
499 * tty->termios contains the new setting to be used.
500 */
ch341_set_termios(struct tty_struct * tty,struct usb_serial_port * port,struct ktermios * old_termios)501 static void ch341_set_termios(struct tty_struct *tty,
502 struct usb_serial_port *port, struct ktermios *old_termios)
503 {
504 struct ch341_private *priv = usb_get_serial_port_data(port);
505 unsigned baud_rate;
506 unsigned long flags;
507 u8 lcr;
508 int r;
509
510 /* redundant changes may cause the chip to lose bytes */
511 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
512 return;
513
514 baud_rate = tty_get_baud_rate(tty);
515
516 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
517
518 switch (C_CSIZE(tty)) {
519 case CS5:
520 lcr |= CH341_LCR_CS5;
521 break;
522 case CS6:
523 lcr |= CH341_LCR_CS6;
524 break;
525 case CS7:
526 lcr |= CH341_LCR_CS7;
527 break;
528 case CS8:
529 lcr |= CH341_LCR_CS8;
530 break;
531 }
532
533 if (C_PARENB(tty)) {
534 lcr |= CH341_LCR_ENABLE_PAR;
535 if (C_PARODD(tty) == 0)
536 lcr |= CH341_LCR_PAR_EVEN;
537 if (C_CMSPAR(tty))
538 lcr |= CH341_LCR_MARK_SPACE;
539 }
540
541 if (C_CSTOPB(tty))
542 lcr |= CH341_LCR_STOP_BITS_2;
543
544 if (baud_rate) {
545 priv->baud_rate = baud_rate;
546
547 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
548 priv->baud_rate, lcr);
549 if (r < 0 && old_termios) {
550 priv->baud_rate = tty_termios_baud_rate(old_termios);
551 tty_termios_copy_hw(&tty->termios, old_termios);
552 } else if (r == 0) {
553 priv->lcr = lcr;
554 }
555 }
556
557 spin_lock_irqsave(&priv->lock, flags);
558 if (C_BAUD(tty) == B0)
559 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
560 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
561 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
562 spin_unlock_irqrestore(&priv->lock, flags);
563
564 ch341_set_handshake(port->serial->dev, priv->mcr);
565 }
566
567 /*
568 * A subset of all CH34x devices don't support a real break condition and
569 * reading CH341_REG_BREAK fails (see also ch341_detect_quirks). This function
570 * simulates a break condition by lowering the baud rate to the minimum
571 * supported by the hardware upon enabling the break condition and sending
572 * a NUL byte.
573 *
574 * Incoming data is corrupted while the break condition is being simulated.
575 *
576 * Normally the duration of the break condition can be controlled individually
577 * by userspace using TIOCSBRK and TIOCCBRK or by passing an argument to
578 * TCSBRKP. Due to how the simulation is implemented the duration can't be
579 * controlled. The duration is always about (1s / 46bd * 9bit) = 196ms.
580 */
ch341_simulate_break(struct tty_struct * tty,int break_state)581 static void ch341_simulate_break(struct tty_struct *tty, int break_state)
582 {
583 struct usb_serial_port *port = tty->driver_data;
584 struct ch341_private *priv = usb_get_serial_port_data(port);
585 unsigned long now, delay;
586 int r;
587
588 if (break_state != 0) {
589 dev_dbg(&port->dev, "enter break state requested\n");
590
591 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
592 CH341_MIN_BPS,
593 CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8);
594 if (r < 0) {
595 dev_err(&port->dev,
596 "failed to change baud rate to %u: %d\n",
597 CH341_MIN_BPS, r);
598 goto restore;
599 }
600
601 r = tty_put_char(tty, '\0');
602 if (r < 0) {
603 dev_err(&port->dev,
604 "failed to write NUL byte for simulated break condition: %d\n",
605 r);
606 goto restore;
607 }
608
609 /*
610 * Compute expected transmission duration including safety
611 * margin. The original baud rate is only restored after the
612 * computed point in time.
613 *
614 * 11 bits = 1 start, 8 data, 1 stop, 1 margin
615 */
616 priv->break_end = jiffies + (11 * HZ / CH341_MIN_BPS);
617
618 return;
619 }
620
621 dev_dbg(&port->dev, "leave break state requested\n");
622
623 now = jiffies;
624
625 if (time_before(now, priv->break_end)) {
626 /* Wait until NUL byte is written */
627 delay = priv->break_end - now;
628 dev_dbg(&port->dev,
629 "wait %d ms while transmitting NUL byte at %u baud\n",
630 jiffies_to_msecs(delay), CH341_MIN_BPS);
631 schedule_timeout_interruptible(delay);
632 }
633
634 restore:
635 /* Restore original baud rate */
636 r = ch341_set_baudrate_lcr(port->serial->dev, priv, priv->baud_rate,
637 priv->lcr);
638 if (r < 0)
639 dev_err(&port->dev,
640 "restoring original baud rate of %u failed: %d\n",
641 priv->baud_rate, r);
642 }
643
ch341_break_ctl(struct tty_struct * tty,int break_state)644 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
645 {
646 const uint16_t ch341_break_reg =
647 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
648 struct usb_serial_port *port = tty->driver_data;
649 struct ch341_private *priv = usb_get_serial_port_data(port);
650 int r;
651 uint16_t reg_contents;
652 uint8_t *break_reg;
653
654 if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK) {
655 ch341_simulate_break(tty, break_state);
656 return;
657 }
658
659 break_reg = kmalloc(2, GFP_KERNEL);
660 if (!break_reg)
661 return;
662
663 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
664 ch341_break_reg, 0, break_reg, 2);
665 if (r < 0) {
666 dev_err(&port->dev, "%s - USB control read error (%d)\n",
667 __func__, r);
668 goto out;
669 }
670 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
671 __func__, break_reg[0], break_reg[1]);
672 if (break_state != 0) {
673 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
674 break_reg[0] &= ~CH341_NBREAK_BITS;
675 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
676 } else {
677 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
678 break_reg[0] |= CH341_NBREAK_BITS;
679 break_reg[1] |= CH341_LCR_ENABLE_TX;
680 }
681 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
682 __func__, break_reg[0], break_reg[1]);
683 reg_contents = get_unaligned_le16(break_reg);
684 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
685 ch341_break_reg, reg_contents);
686 if (r < 0)
687 dev_err(&port->dev, "%s - USB control write error (%d)\n",
688 __func__, r);
689 out:
690 kfree(break_reg);
691 }
692
ch341_tiocmset(struct tty_struct * tty,unsigned int set,unsigned int clear)693 static int ch341_tiocmset(struct tty_struct *tty,
694 unsigned int set, unsigned int clear)
695 {
696 struct usb_serial_port *port = tty->driver_data;
697 struct ch341_private *priv = usb_get_serial_port_data(port);
698 unsigned long flags;
699 u8 control;
700
701 spin_lock_irqsave(&priv->lock, flags);
702 if (set & TIOCM_RTS)
703 priv->mcr |= CH341_BIT_RTS;
704 if (set & TIOCM_DTR)
705 priv->mcr |= CH341_BIT_DTR;
706 if (clear & TIOCM_RTS)
707 priv->mcr &= ~CH341_BIT_RTS;
708 if (clear & TIOCM_DTR)
709 priv->mcr &= ~CH341_BIT_DTR;
710 control = priv->mcr;
711 spin_unlock_irqrestore(&priv->lock, flags);
712
713 return ch341_set_handshake(port->serial->dev, control);
714 }
715
ch341_update_status(struct usb_serial_port * port,unsigned char * data,size_t len)716 static void ch341_update_status(struct usb_serial_port *port,
717 unsigned char *data, size_t len)
718 {
719 struct ch341_private *priv = usb_get_serial_port_data(port);
720 struct tty_struct *tty;
721 unsigned long flags;
722 u8 status;
723 u8 delta;
724
725 if (len < 4)
726 return;
727
728 status = ~data[2] & CH341_BITS_MODEM_STAT;
729
730 spin_lock_irqsave(&priv->lock, flags);
731 delta = status ^ priv->msr;
732 priv->msr = status;
733 spin_unlock_irqrestore(&priv->lock, flags);
734
735 if (data[1] & CH341_MULT_STAT)
736 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
737
738 if (!delta)
739 return;
740
741 if (delta & CH341_BIT_CTS)
742 port->icount.cts++;
743 if (delta & CH341_BIT_DSR)
744 port->icount.dsr++;
745 if (delta & CH341_BIT_RI)
746 port->icount.rng++;
747 if (delta & CH341_BIT_DCD) {
748 port->icount.dcd++;
749 tty = tty_port_tty_get(&port->port);
750 if (tty) {
751 usb_serial_handle_dcd_change(port, tty,
752 status & CH341_BIT_DCD);
753 tty_kref_put(tty);
754 }
755 }
756
757 wake_up_interruptible(&port->port.delta_msr_wait);
758 }
759
ch341_read_int_callback(struct urb * urb)760 static void ch341_read_int_callback(struct urb *urb)
761 {
762 struct usb_serial_port *port = urb->context;
763 unsigned char *data = urb->transfer_buffer;
764 unsigned int len = urb->actual_length;
765 int status;
766
767 switch (urb->status) {
768 case 0:
769 /* success */
770 break;
771 case -ECONNRESET:
772 case -ENOENT:
773 case -ESHUTDOWN:
774 /* this urb is terminated, clean up */
775 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
776 __func__, urb->status);
777 return;
778 default:
779 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
780 __func__, urb->status);
781 goto exit;
782 }
783
784 usb_serial_debug_data(&port->dev, __func__, len, data);
785 ch341_update_status(port, data, len);
786 exit:
787 status = usb_submit_urb(urb, GFP_ATOMIC);
788 if (status) {
789 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
790 __func__, status);
791 }
792 }
793
ch341_tiocmget(struct tty_struct * tty)794 static int ch341_tiocmget(struct tty_struct *tty)
795 {
796 struct usb_serial_port *port = tty->driver_data;
797 struct ch341_private *priv = usb_get_serial_port_data(port);
798 unsigned long flags;
799 u8 mcr;
800 u8 status;
801 unsigned int result;
802
803 spin_lock_irqsave(&priv->lock, flags);
804 mcr = priv->mcr;
805 status = priv->msr;
806 spin_unlock_irqrestore(&priv->lock, flags);
807
808 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
809 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
810 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
811 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
812 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
813 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
814
815 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
816
817 return result;
818 }
819
ch341_reset_resume(struct usb_serial * serial)820 static int ch341_reset_resume(struct usb_serial *serial)
821 {
822 struct usb_serial_port *port = serial->port[0];
823 struct ch341_private *priv;
824 int ret;
825
826 priv = usb_get_serial_port_data(port);
827 if (!priv)
828 return 0;
829
830 /* reconfigure ch341 serial port after bus-reset */
831 ch341_configure(serial->dev, priv);
832
833 if (tty_port_initialized(&port->port)) {
834 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
835 if (ret) {
836 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
837 ret);
838 return ret;
839 }
840
841 ret = ch341_get_status(port->serial->dev, priv);
842 if (ret < 0) {
843 dev_err(&port->dev, "failed to read modem status: %d\n",
844 ret);
845 }
846 }
847
848 return usb_serial_generic_resume(serial);
849 }
850
851 static struct usb_serial_driver ch341_device = {
852 .driver = {
853 .owner = THIS_MODULE,
854 .name = "ch341-uart",
855 },
856 .id_table = id_table,
857 .num_ports = 1,
858 .open = ch341_open,
859 .dtr_rts = ch341_dtr_rts,
860 .carrier_raised = ch341_carrier_raised,
861 .close = ch341_close,
862 .set_termios = ch341_set_termios,
863 .break_ctl = ch341_break_ctl,
864 .tiocmget = ch341_tiocmget,
865 .tiocmset = ch341_tiocmset,
866 .tiocmiwait = usb_serial_generic_tiocmiwait,
867 .read_int_callback = ch341_read_int_callback,
868 .port_probe = ch341_port_probe,
869 .port_remove = ch341_port_remove,
870 .reset_resume = ch341_reset_resume,
871 };
872
873 static struct usb_serial_driver * const serial_drivers[] = {
874 &ch341_device, NULL
875 };
876
877 module_usb_serial_driver(serial_drivers, id_table);
878
879 MODULE_LICENSE("GPL v2");
880