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, 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 };
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
101 unsigned long quirks;
102 u8 version;
103
104 unsigned long break_end;
105 };
106
107 static void ch341_set_termios(struct tty_struct *tty,
108 struct usb_serial_port *port,
109 const struct ktermios *old_termios);
110
ch341_control_out(struct usb_device * dev,u8 request,u16 value,u16 index)111 static int ch341_control_out(struct usb_device *dev, u8 request,
112 u16 value, u16 index)
113 {
114 int r;
115
116 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
117 request, value, index);
118
119 r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
120 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
121 value, index, NULL, 0, DEFAULT_TIMEOUT);
122 if (r < 0)
123 dev_err(&dev->dev, "failed to send control message: %d\n", r);
124
125 return r;
126 }
127
ch341_control_in(struct usb_device * dev,u8 request,u16 value,u16 index,char * buf,unsigned bufsize)128 static int ch341_control_in(struct usb_device *dev,
129 u8 request, u16 value, u16 index,
130 char *buf, unsigned bufsize)
131 {
132 int r;
133
134 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
135 request, value, index, bufsize);
136
137 r = usb_control_msg_recv(dev, 0, request,
138 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
139 value, index, buf, bufsize, DEFAULT_TIMEOUT,
140 GFP_KERNEL);
141 if (r) {
142 dev_err(&dev->dev, "failed to receive control message: %d\n",
143 r);
144 return r;
145 }
146
147 return 0;
148 }
149
150 #define CH341_CLKRATE 48000000
151 #define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
152 #define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
153
154 static const speed_t ch341_min_rates[] = {
155 CH341_MIN_RATE(0),
156 CH341_MIN_RATE(1),
157 CH341_MIN_RATE(2),
158 CH341_MIN_RATE(3),
159 };
160
161 /* Supported range is 46 to 3000000 bps. */
162 #define CH341_MIN_BPS DIV_ROUND_UP(CH341_CLKRATE, CH341_CLK_DIV(0, 0) * 256)
163 #define CH341_MAX_BPS (CH341_CLKRATE / (CH341_CLK_DIV(3, 0) * 2))
164
165 /*
166 * The device line speed is given by the following equation:
167 *
168 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
169 *
170 * 0 <= ps <= 3,
171 * 0 <= fact <= 1,
172 * 2 <= div <= 256 if fact = 0, or
173 * 9 <= div <= 256 if fact = 1
174 */
ch341_get_divisor(struct ch341_private * priv,speed_t speed)175 static int ch341_get_divisor(struct ch341_private *priv, speed_t speed)
176 {
177 unsigned int fact, div, clk_div;
178 bool force_fact0 = false;
179 int ps;
180
181 /*
182 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
183 * sanity checks below redundant.
184 */
185 speed = clamp_val(speed, CH341_MIN_BPS, CH341_MAX_BPS);
186
187 /*
188 * Start with highest possible base clock (fact = 1) that will give a
189 * divisor strictly less than 512.
190 */
191 fact = 1;
192 for (ps = 3; ps >= 0; ps--) {
193 if (speed > ch341_min_rates[ps])
194 break;
195 }
196
197 if (ps < 0)
198 return -EINVAL;
199
200 /* Determine corresponding divisor, rounding down. */
201 clk_div = CH341_CLK_DIV(ps, fact);
202 div = CH341_CLKRATE / (clk_div * speed);
203
204 /* Some devices require a lower base clock if ps < 3. */
205 if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER))
206 force_fact0 = true;
207
208 /* Halve base clock (fact = 0) if required. */
209 if (div < 9 || div > 255 || force_fact0) {
210 div /= 2;
211 clk_div *= 2;
212 fact = 0;
213 }
214
215 if (div < 2)
216 return -EINVAL;
217
218 /*
219 * Pick next divisor if resulting rate is closer to the requested one,
220 * scale up to avoid rounding errors on low rates.
221 */
222 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
223 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
224 div++;
225
226 /*
227 * Prefer lower base clock (fact = 0) if even divisor.
228 *
229 * Note that this makes the receiver more tolerant to errors.
230 */
231 if (fact == 1 && div % 2 == 0) {
232 div /= 2;
233 fact = 0;
234 }
235
236 return (0x100 - div) << 8 | fact << 2 | ps;
237 }
238
ch341_set_baudrate_lcr(struct usb_device * dev,struct ch341_private * priv,speed_t baud_rate,u8 lcr)239 static int ch341_set_baudrate_lcr(struct usb_device *dev,
240 struct ch341_private *priv,
241 speed_t baud_rate, u8 lcr)
242 {
243 int val;
244 int r;
245
246 if (!baud_rate)
247 return -EINVAL;
248
249 val = ch341_get_divisor(priv, baud_rate);
250 if (val < 0)
251 return -EINVAL;
252
253 /*
254 * CH341A buffers data until a full endpoint-size packet (32 bytes)
255 * has been received unless bit 7 is set.
256 *
257 * At least one device with version 0x27 appears to have this bit
258 * inverted.
259 */
260 if (priv->version > 0x27)
261 val |= BIT(7);
262
263 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
264 CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
265 val);
266 if (r)
267 return r;
268
269 /*
270 * Chip versions before version 0x30 as read using
271 * CH341_REQ_READ_VERSION used separate registers for line control
272 * (stop bits, parity and word length). Version 0x30 and above use
273 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
274 */
275 if (priv->version < 0x30)
276 return 0;
277
278 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
279 CH341_REG_LCR2 << 8 | CH341_REG_LCR, lcr);
280 if (r)
281 return r;
282
283 return r;
284 }
285
ch341_set_handshake(struct usb_device * dev,u8 control)286 static int ch341_set_handshake(struct usb_device *dev, u8 control)
287 {
288 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
289 }
290
ch341_get_status(struct usb_device * dev,struct ch341_private * priv)291 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
292 {
293 const unsigned int size = 2;
294 u8 buffer[2];
295 int r;
296 unsigned long flags;
297
298 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
299 if (r)
300 return r;
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 return 0;
307 }
308
309 /* -------------------------------------------------------------------------- */
310
ch341_configure(struct usb_device * dev,struct ch341_private * priv)311 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
312 {
313 const unsigned int size = 2;
314 u8 buffer[2];
315 int r;
316
317 /* expect two bytes 0x27 0x00 */
318 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
319 if (r)
320 return r;
321
322 priv->version = buffer[0];
323 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", priv->version);
324
325 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
326 if (r < 0)
327 return r;
328
329 r = ch341_set_baudrate_lcr(dev, priv, priv->baud_rate, priv->lcr);
330 if (r < 0)
331 return r;
332
333 r = ch341_set_handshake(dev, priv->mcr);
334 if (r < 0)
335 return r;
336
337 return 0;
338 }
339
ch341_detect_quirks(struct usb_serial_port * port)340 static int ch341_detect_quirks(struct usb_serial_port *port)
341 {
342 struct ch341_private *priv = usb_get_serial_port_data(port);
343 struct usb_device *udev = port->serial->dev;
344 const unsigned int size = 2;
345 unsigned long quirks = 0;
346 u8 buffer[2];
347 int r;
348
349 /*
350 * A subset of CH34x devices does not support all features. The
351 * prescaler is limited and there is no support for sending a RS232
352 * break condition. A read failure when trying to set up the latter is
353 * used to detect these devices.
354 */
355 r = usb_control_msg_recv(udev, 0, CH341_REQ_READ_REG,
356 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
357 CH341_REG_BREAK, 0, &buffer, size,
358 DEFAULT_TIMEOUT, GFP_KERNEL);
359 if (r == -EPIPE) {
360 dev_info(&port->dev, "break control not supported, using simulated break\n");
361 quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK;
362 r = 0;
363 } else if (r) {
364 dev_err(&port->dev, "failed to read break control: %d\n", r);
365 }
366
367 if (quirks) {
368 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
369 priv->quirks |= quirks;
370 }
371
372 return r;
373 }
374
ch341_port_probe(struct usb_serial_port * port)375 static int ch341_port_probe(struct usb_serial_port *port)
376 {
377 struct ch341_private *priv;
378 int r;
379
380 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
381 if (!priv)
382 return -ENOMEM;
383
384 spin_lock_init(&priv->lock);
385 priv->baud_rate = DEFAULT_BAUD_RATE;
386 /*
387 * Some CH340 devices appear unable to change the initial LCR
388 * settings, so set a sane 8N1 default.
389 */
390 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
391
392 r = ch341_configure(port->serial->dev, priv);
393 if (r < 0)
394 goto error;
395
396 usb_set_serial_port_data(port, priv);
397
398 r = ch341_detect_quirks(port);
399 if (r < 0)
400 goto error;
401
402 return 0;
403
404 error: kfree(priv);
405 return r;
406 }
407
ch341_port_remove(struct usb_serial_port * port)408 static void ch341_port_remove(struct usb_serial_port *port)
409 {
410 struct ch341_private *priv;
411
412 priv = usb_get_serial_port_data(port);
413 kfree(priv);
414 }
415
ch341_carrier_raised(struct usb_serial_port * port)416 static int ch341_carrier_raised(struct usb_serial_port *port)
417 {
418 struct ch341_private *priv = usb_get_serial_port_data(port);
419 if (priv->msr & CH341_BIT_DCD)
420 return 1;
421 return 0;
422 }
423
ch341_dtr_rts(struct usb_serial_port * port,int on)424 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
425 {
426 struct ch341_private *priv = usb_get_serial_port_data(port);
427 unsigned long flags;
428
429 /* drop DTR and RTS */
430 spin_lock_irqsave(&priv->lock, flags);
431 if (on)
432 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
433 else
434 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
435 spin_unlock_irqrestore(&priv->lock, flags);
436 ch341_set_handshake(port->serial->dev, priv->mcr);
437 }
438
ch341_close(struct usb_serial_port * port)439 static void ch341_close(struct usb_serial_port *port)
440 {
441 usb_serial_generic_close(port);
442 usb_kill_urb(port->interrupt_in_urb);
443 }
444
445
446 /* open this device, set default parameters */
ch341_open(struct tty_struct * tty,struct usb_serial_port * port)447 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
448 {
449 struct ch341_private *priv = usb_get_serial_port_data(port);
450 int r;
451
452 if (tty)
453 ch341_set_termios(tty, port, NULL);
454
455 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
456 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
457 if (r) {
458 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
459 __func__, r);
460 return r;
461 }
462
463 r = ch341_get_status(port->serial->dev, priv);
464 if (r < 0) {
465 dev_err(&port->dev, "failed to read modem status: %d\n", r);
466 goto err_kill_interrupt_urb;
467 }
468
469 r = usb_serial_generic_open(tty, port);
470 if (r)
471 goto err_kill_interrupt_urb;
472
473 return 0;
474
475 err_kill_interrupt_urb:
476 usb_kill_urb(port->interrupt_in_urb);
477
478 return r;
479 }
480
481 /* Old_termios contains the original termios settings and
482 * tty->termios contains the new setting to be used.
483 */
ch341_set_termios(struct tty_struct * tty,struct usb_serial_port * port,const struct ktermios * old_termios)484 static void ch341_set_termios(struct tty_struct *tty,
485 struct usb_serial_port *port,
486 const struct ktermios *old_termios)
487 {
488 struct ch341_private *priv = usb_get_serial_port_data(port);
489 unsigned baud_rate;
490 unsigned long flags;
491 u8 lcr;
492 int r;
493
494 /* redundant changes may cause the chip to lose bytes */
495 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
496 return;
497
498 baud_rate = tty_get_baud_rate(tty);
499
500 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
501
502 switch (C_CSIZE(tty)) {
503 case CS5:
504 lcr |= CH341_LCR_CS5;
505 break;
506 case CS6:
507 lcr |= CH341_LCR_CS6;
508 break;
509 case CS7:
510 lcr |= CH341_LCR_CS7;
511 break;
512 case CS8:
513 lcr |= CH341_LCR_CS8;
514 break;
515 }
516
517 if (C_PARENB(tty)) {
518 lcr |= CH341_LCR_ENABLE_PAR;
519 if (C_PARODD(tty) == 0)
520 lcr |= CH341_LCR_PAR_EVEN;
521 if (C_CMSPAR(tty))
522 lcr |= CH341_LCR_MARK_SPACE;
523 }
524
525 if (C_CSTOPB(tty))
526 lcr |= CH341_LCR_STOP_BITS_2;
527
528 if (baud_rate) {
529 priv->baud_rate = baud_rate;
530
531 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
532 priv->baud_rate, lcr);
533 if (r < 0 && old_termios) {
534 priv->baud_rate = tty_termios_baud_rate(old_termios);
535 tty_termios_copy_hw(&tty->termios, old_termios);
536 } else if (r == 0) {
537 priv->lcr = lcr;
538 }
539 }
540
541 spin_lock_irqsave(&priv->lock, flags);
542 if (C_BAUD(tty) == B0)
543 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
544 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
545 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
546 spin_unlock_irqrestore(&priv->lock, flags);
547
548 ch341_set_handshake(port->serial->dev, priv->mcr);
549 }
550
551 /*
552 * A subset of all CH34x devices don't support a real break condition and
553 * reading CH341_REG_BREAK fails (see also ch341_detect_quirks). This function
554 * simulates a break condition by lowering the baud rate to the minimum
555 * supported by the hardware upon enabling the break condition and sending
556 * a NUL byte.
557 *
558 * Incoming data is corrupted while the break condition is being simulated.
559 *
560 * Normally the duration of the break condition can be controlled individually
561 * by userspace using TIOCSBRK and TIOCCBRK or by passing an argument to
562 * TCSBRKP. Due to how the simulation is implemented the duration can't be
563 * controlled. The duration is always about (1s / 46bd * 9bit) = 196ms.
564 */
ch341_simulate_break(struct tty_struct * tty,int break_state)565 static int ch341_simulate_break(struct tty_struct *tty, int break_state)
566 {
567 struct usb_serial_port *port = tty->driver_data;
568 struct ch341_private *priv = usb_get_serial_port_data(port);
569 unsigned long now, delay;
570 int r, r2;
571
572 if (break_state != 0) {
573 dev_dbg(&port->dev, "enter break state requested\n");
574
575 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
576 CH341_MIN_BPS,
577 CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8);
578 if (r < 0) {
579 dev_err(&port->dev,
580 "failed to change baud rate to %u: %d\n",
581 CH341_MIN_BPS, r);
582 goto restore;
583 }
584
585 r = tty_put_char(tty, '\0');
586 if (r < 0) {
587 dev_err(&port->dev,
588 "failed to write NUL byte for simulated break condition: %d\n",
589 r);
590 goto restore;
591 }
592
593 /*
594 * Compute expected transmission duration including safety
595 * margin. The original baud rate is only restored after the
596 * computed point in time.
597 *
598 * 11 bits = 1 start, 8 data, 1 stop, 1 margin
599 */
600 priv->break_end = jiffies + (11 * HZ / CH341_MIN_BPS);
601
602 return 0;
603 }
604
605 dev_dbg(&port->dev, "leave break state requested\n");
606
607 now = jiffies;
608
609 if (time_before(now, priv->break_end)) {
610 /* Wait until NUL byte is written */
611 delay = priv->break_end - now;
612 dev_dbg(&port->dev,
613 "wait %d ms while transmitting NUL byte at %u baud\n",
614 jiffies_to_msecs(delay), CH341_MIN_BPS);
615 schedule_timeout_interruptible(delay);
616 }
617
618 r = 0;
619 restore:
620 /* Restore original baud rate */
621 r2 = ch341_set_baudrate_lcr(port->serial->dev, priv, priv->baud_rate,
622 priv->lcr);
623 if (r2 < 0) {
624 dev_err(&port->dev,
625 "restoring original baud rate of %u failed: %d\n",
626 priv->baud_rate, r2);
627 return r2;
628 }
629
630 return r;
631 }
632
ch341_break_ctl(struct tty_struct * tty,int break_state)633 static int ch341_break_ctl(struct tty_struct *tty, int break_state)
634 {
635 const uint16_t ch341_break_reg =
636 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
637 struct usb_serial_port *port = tty->driver_data;
638 struct ch341_private *priv = usb_get_serial_port_data(port);
639 int r;
640 uint16_t reg_contents;
641 uint8_t break_reg[2];
642
643 if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK)
644 return ch341_simulate_break(tty, break_state);
645
646 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
647 ch341_break_reg, 0, break_reg, 2);
648 if (r) {
649 dev_err(&port->dev, "%s - USB control read error (%d)\n",
650 __func__, r);
651 if (r > 0)
652 r = -EIO;
653 return r;
654 }
655 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
656 __func__, break_reg[0], break_reg[1]);
657 if (break_state != 0) {
658 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
659 break_reg[0] &= ~CH341_NBREAK_BITS;
660 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
661 } else {
662 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
663 break_reg[0] |= CH341_NBREAK_BITS;
664 break_reg[1] |= CH341_LCR_ENABLE_TX;
665 }
666 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
667 __func__, break_reg[0], break_reg[1]);
668 reg_contents = get_unaligned_le16(break_reg);
669 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
670 ch341_break_reg, reg_contents);
671 if (r < 0) {
672 dev_err(&port->dev, "%s - USB control write error (%d)\n",
673 __func__, r);
674 return r;
675 }
676
677 return 0;
678 }
679
ch341_tiocmset(struct tty_struct * tty,unsigned int set,unsigned int clear)680 static int ch341_tiocmset(struct tty_struct *tty,
681 unsigned int set, unsigned int clear)
682 {
683 struct usb_serial_port *port = tty->driver_data;
684 struct ch341_private *priv = usb_get_serial_port_data(port);
685 unsigned long flags;
686 u8 control;
687
688 spin_lock_irqsave(&priv->lock, flags);
689 if (set & TIOCM_RTS)
690 priv->mcr |= CH341_BIT_RTS;
691 if (set & TIOCM_DTR)
692 priv->mcr |= CH341_BIT_DTR;
693 if (clear & TIOCM_RTS)
694 priv->mcr &= ~CH341_BIT_RTS;
695 if (clear & TIOCM_DTR)
696 priv->mcr &= ~CH341_BIT_DTR;
697 control = priv->mcr;
698 spin_unlock_irqrestore(&priv->lock, flags);
699
700 return ch341_set_handshake(port->serial->dev, control);
701 }
702
ch341_update_status(struct usb_serial_port * port,unsigned char * data,size_t len)703 static void ch341_update_status(struct usb_serial_port *port,
704 unsigned char *data, size_t len)
705 {
706 struct ch341_private *priv = usb_get_serial_port_data(port);
707 struct tty_struct *tty;
708 unsigned long flags;
709 u8 status;
710 u8 delta;
711
712 if (len < 4)
713 return;
714
715 status = ~data[2] & CH341_BITS_MODEM_STAT;
716
717 spin_lock_irqsave(&priv->lock, flags);
718 delta = status ^ priv->msr;
719 priv->msr = status;
720 spin_unlock_irqrestore(&priv->lock, flags);
721
722 if (data[1] & CH341_MULT_STAT)
723 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
724
725 if (!delta)
726 return;
727
728 if (delta & CH341_BIT_CTS)
729 port->icount.cts++;
730 if (delta & CH341_BIT_DSR)
731 port->icount.dsr++;
732 if (delta & CH341_BIT_RI)
733 port->icount.rng++;
734 if (delta & CH341_BIT_DCD) {
735 port->icount.dcd++;
736 tty = tty_port_tty_get(&port->port);
737 if (tty) {
738 usb_serial_handle_dcd_change(port, tty,
739 status & CH341_BIT_DCD);
740 tty_kref_put(tty);
741 }
742 }
743
744 wake_up_interruptible(&port->port.delta_msr_wait);
745 }
746
ch341_read_int_callback(struct urb * urb)747 static void ch341_read_int_callback(struct urb *urb)
748 {
749 struct usb_serial_port *port = urb->context;
750 unsigned char *data = urb->transfer_buffer;
751 unsigned int len = urb->actual_length;
752 int status;
753
754 switch (urb->status) {
755 case 0:
756 /* success */
757 break;
758 case -ECONNRESET:
759 case -ENOENT:
760 case -ESHUTDOWN:
761 /* this urb is terminated, clean up */
762 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
763 __func__, urb->status);
764 return;
765 default:
766 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
767 __func__, urb->status);
768 goto exit;
769 }
770
771 usb_serial_debug_data(&port->dev, __func__, len, data);
772 ch341_update_status(port, data, len);
773 exit:
774 status = usb_submit_urb(urb, GFP_ATOMIC);
775 if (status) {
776 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
777 __func__, status);
778 }
779 }
780
ch341_tiocmget(struct tty_struct * tty)781 static int ch341_tiocmget(struct tty_struct *tty)
782 {
783 struct usb_serial_port *port = tty->driver_data;
784 struct ch341_private *priv = usb_get_serial_port_data(port);
785 unsigned long flags;
786 u8 mcr;
787 u8 status;
788 unsigned int result;
789
790 spin_lock_irqsave(&priv->lock, flags);
791 mcr = priv->mcr;
792 status = priv->msr;
793 spin_unlock_irqrestore(&priv->lock, flags);
794
795 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
796 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
797 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
798 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
799 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
800 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
801
802 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
803
804 return result;
805 }
806
ch341_reset_resume(struct usb_serial * serial)807 static int ch341_reset_resume(struct usb_serial *serial)
808 {
809 struct usb_serial_port *port = serial->port[0];
810 struct ch341_private *priv;
811 int ret;
812
813 priv = usb_get_serial_port_data(port);
814 if (!priv)
815 return 0;
816
817 /* reconfigure ch341 serial port after bus-reset */
818 ch341_configure(serial->dev, priv);
819
820 if (tty_port_initialized(&port->port)) {
821 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
822 if (ret) {
823 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
824 ret);
825 return ret;
826 }
827
828 ret = ch341_get_status(port->serial->dev, priv);
829 if (ret < 0) {
830 dev_err(&port->dev, "failed to read modem status: %d\n",
831 ret);
832 }
833 }
834
835 return usb_serial_generic_resume(serial);
836 }
837
838 static struct usb_serial_driver ch341_device = {
839 .driver = {
840 .owner = THIS_MODULE,
841 .name = "ch341-uart",
842 },
843 .id_table = id_table,
844 .num_ports = 1,
845 .open = ch341_open,
846 .dtr_rts = ch341_dtr_rts,
847 .carrier_raised = ch341_carrier_raised,
848 .close = ch341_close,
849 .set_termios = ch341_set_termios,
850 .break_ctl = ch341_break_ctl,
851 .tiocmget = ch341_tiocmget,
852 .tiocmset = ch341_tiocmset,
853 .tiocmiwait = usb_serial_generic_tiocmiwait,
854 .read_int_callback = ch341_read_int_callback,
855 .port_probe = ch341_port_probe,
856 .port_remove = ch341_port_remove,
857 .reset_resume = ch341_reset_resume,
858 };
859
860 static struct usb_serial_driver * const serial_drivers[] = {
861 &ch341_device, NULL
862 };
863
864 module_usb_serial_driver(serial_drivers, id_table);
865
866 MODULE_LICENSE("GPL v2");
867