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 { },
90 };
91 MODULE_DEVICE_TABLE(usb, id_table);
92
93 struct ch341_private {
94 spinlock_t lock; /* access lock */
95 unsigned baud_rate; /* set baud rate */
96 u8 mcr;
97 u8 msr;
98 u8 lcr;
99 unsigned long quirks;
100 unsigned long break_end;
101 };
102
103 static void ch341_set_termios(struct tty_struct *tty,
104 struct usb_serial_port *port,
105 struct ktermios *old_termios);
106
ch341_control_out(struct usb_device * dev,u8 request,u16 value,u16 index)107 static int ch341_control_out(struct usb_device *dev, u8 request,
108 u16 value, u16 index)
109 {
110 int r;
111
112 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
113 request, value, index);
114
115 r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
116 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
117 value, index, NULL, 0, DEFAULT_TIMEOUT);
118 if (r < 0)
119 dev_err(&dev->dev, "failed to send control message: %d\n", r);
120
121 return r;
122 }
123
ch341_control_in(struct usb_device * dev,u8 request,u16 value,u16 index,char * buf,unsigned bufsize)124 static int ch341_control_in(struct usb_device *dev,
125 u8 request, u16 value, u16 index,
126 char *buf, unsigned bufsize)
127 {
128 int r;
129
130 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
131 request, value, index, bufsize);
132
133 r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
134 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
135 value, index, buf, bufsize, DEFAULT_TIMEOUT);
136 if (r < (int)bufsize) {
137 if (r >= 0) {
138 dev_err(&dev->dev,
139 "short control message received (%d < %u)\n",
140 r, bufsize);
141 r = -EIO;
142 }
143
144 dev_err(&dev->dev, "failed to receive control message: %d\n",
145 r);
146 return r;
147 }
148
149 return 0;
150 }
151
152 #define CH341_CLKRATE 48000000
153 #define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
154 #define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
155
156 static const speed_t ch341_min_rates[] = {
157 CH341_MIN_RATE(0),
158 CH341_MIN_RATE(1),
159 CH341_MIN_RATE(2),
160 CH341_MIN_RATE(3),
161 };
162
163 /* Supported range is 46 to 3000000 bps. */
164 #define CH341_MIN_BPS DIV_ROUND_UP(CH341_CLKRATE, CH341_CLK_DIV(0, 0) * 256)
165 #define CH341_MAX_BPS (CH341_CLKRATE / (CH341_CLK_DIV(3, 0) * 2))
166
167 /*
168 * The device line speed is given by the following equation:
169 *
170 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
171 *
172 * 0 <= ps <= 3,
173 * 0 <= fact <= 1,
174 * 2 <= div <= 256 if fact = 0, or
175 * 9 <= div <= 256 if fact = 1
176 */
ch341_get_divisor(struct ch341_private * priv,speed_t speed)177 static int ch341_get_divisor(struct ch341_private *priv, speed_t speed)
178 {
179 unsigned int fact, div, clk_div;
180 bool force_fact0 = false;
181 int ps;
182
183 /*
184 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
185 * sanity checks below redundant.
186 */
187 speed = clamp_val(speed, CH341_MIN_BPS, CH341_MAX_BPS);
188
189 /*
190 * Start with highest possible base clock (fact = 1) that will give a
191 * divisor strictly less than 512.
192 */
193 fact = 1;
194 for (ps = 3; ps >= 0; ps--) {
195 if (speed > ch341_min_rates[ps])
196 break;
197 }
198
199 if (ps < 0)
200 return -EINVAL;
201
202 /* Determine corresponding divisor, rounding down. */
203 clk_div = CH341_CLK_DIV(ps, fact);
204 div = CH341_CLKRATE / (clk_div * speed);
205
206 /* Some devices require a lower base clock if ps < 3. */
207 if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER))
208 force_fact0 = true;
209
210 /* Halve base clock (fact = 0) if required. */
211 if (div < 9 || div > 255 || force_fact0) {
212 div /= 2;
213 clk_div *= 2;
214 fact = 0;
215 }
216
217 if (div < 2)
218 return -EINVAL;
219
220 /*
221 * Pick next divisor if resulting rate is closer to the requested one,
222 * scale up to avoid rounding errors on low rates.
223 */
224 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
225 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
226 div++;
227
228 /*
229 * Prefer lower base clock (fact = 0) if even divisor.
230 *
231 * Note that this makes the receiver more tolerant to errors.
232 */
233 if (fact == 1 && div % 2 == 0) {
234 div /= 2;
235 fact = 0;
236 }
237
238 return (0x100 - div) << 8 | fact << 2 | ps;
239 }
240
ch341_set_baudrate_lcr(struct usb_device * dev,struct ch341_private * priv,speed_t baud_rate,u8 lcr)241 static int ch341_set_baudrate_lcr(struct usb_device *dev,
242 struct ch341_private *priv,
243 speed_t baud_rate, u8 lcr)
244 {
245 int val;
246 int r;
247
248 if (!baud_rate)
249 return -EINVAL;
250
251 val = ch341_get_divisor(priv, baud_rate);
252 if (val < 0)
253 return -EINVAL;
254
255 /*
256 * CH341A buffers data until a full endpoint-size packet (32 bytes)
257 * has been received unless bit 7 is set.
258 */
259 val |= BIT(7);
260
261 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
262 CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
263 val);
264 if (r)
265 return r;
266
267 /*
268 * Chip versions before version 0x30 as read using
269 * CH341_REQ_READ_VERSION used separate registers for line control
270 * (stop bits, parity and word length). Version 0x30 and above use
271 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
272 */
273 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
274 CH341_REG_LCR2 << 8 | CH341_REG_LCR, lcr);
275 if (r)
276 return r;
277
278 return r;
279 }
280
ch341_set_handshake(struct usb_device * dev,u8 control)281 static int ch341_set_handshake(struct usb_device *dev, u8 control)
282 {
283 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
284 }
285
ch341_get_status(struct usb_device * dev,struct ch341_private * priv)286 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
287 {
288 const unsigned int size = 2;
289 char *buffer;
290 int r;
291 unsigned long flags;
292
293 buffer = kmalloc(size, GFP_KERNEL);
294 if (!buffer)
295 return -ENOMEM;
296
297 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
298 if (r < 0)
299 goto out;
300
301 spin_lock_irqsave(&priv->lock, flags);
302 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
303 spin_unlock_irqrestore(&priv->lock, flags);
304
305 out: kfree(buffer);
306 return r;
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 char *buffer;
315 int r;
316
317 buffer = kmalloc(size, GFP_KERNEL);
318 if (!buffer)
319 return -ENOMEM;
320
321 /* expect two bytes 0x27 0x00 */
322 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
323 if (r < 0)
324 goto out;
325 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
326
327 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
328 if (r < 0)
329 goto out;
330
331 r = ch341_set_baudrate_lcr(dev, priv, priv->baud_rate, priv->lcr);
332 if (r < 0)
333 goto out;
334
335 r = ch341_set_handshake(dev, priv->mcr);
336
337 out: kfree(buffer);
338 return r;
339 }
340
ch341_detect_quirks(struct usb_serial_port * port)341 static int ch341_detect_quirks(struct usb_serial_port *port)
342 {
343 struct ch341_private *priv = usb_get_serial_port_data(port);
344 struct usb_device *udev = port->serial->dev;
345 const unsigned int size = 2;
346 unsigned long quirks = 0;
347 char *buffer;
348 int r;
349
350 buffer = kmalloc(size, GFP_KERNEL);
351 if (!buffer)
352 return -ENOMEM;
353
354 /*
355 * A subset of CH34x devices does not support all features. The
356 * prescaler is limited and there is no support for sending a RS232
357 * break condition. A read failure when trying to set up the latter is
358 * used to detect these devices.
359 */
360 r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG,
361 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
362 CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT);
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 goto out;
368 }
369
370 if (r != size) {
371 if (r >= 0)
372 r = -EIO;
373 dev_err(&port->dev, "failed to read break control: %d\n", r);
374 goto out;
375 }
376
377 r = 0;
378 out:
379 kfree(buffer);
380
381 if (quirks) {
382 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
383 priv->quirks |= quirks;
384 }
385
386 return r;
387 }
388
ch341_port_probe(struct usb_serial_port * port)389 static int ch341_port_probe(struct usb_serial_port *port)
390 {
391 struct ch341_private *priv;
392 int r;
393
394 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
395 if (!priv)
396 return -ENOMEM;
397
398 spin_lock_init(&priv->lock);
399 priv->baud_rate = DEFAULT_BAUD_RATE;
400 /*
401 * Some CH340 devices appear unable to change the initial LCR
402 * settings, so set a sane 8N1 default.
403 */
404 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
405
406 r = ch341_configure(port->serial->dev, priv);
407 if (r < 0)
408 goto error;
409
410 usb_set_serial_port_data(port, priv);
411
412 r = ch341_detect_quirks(port);
413 if (r < 0)
414 goto error;
415
416 return 0;
417
418 error: kfree(priv);
419 return r;
420 }
421
ch341_port_remove(struct usb_serial_port * port)422 static int ch341_port_remove(struct usb_serial_port *port)
423 {
424 struct ch341_private *priv;
425
426 priv = usb_get_serial_port_data(port);
427 kfree(priv);
428
429 return 0;
430 }
431
ch341_carrier_raised(struct usb_serial_port * port)432 static int ch341_carrier_raised(struct usb_serial_port *port)
433 {
434 struct ch341_private *priv = usb_get_serial_port_data(port);
435 if (priv->msr & CH341_BIT_DCD)
436 return 1;
437 return 0;
438 }
439
ch341_dtr_rts(struct usb_serial_port * port,int on)440 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
441 {
442 struct ch341_private *priv = usb_get_serial_port_data(port);
443 unsigned long flags;
444
445 /* drop DTR and RTS */
446 spin_lock_irqsave(&priv->lock, flags);
447 if (on)
448 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
449 else
450 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
451 spin_unlock_irqrestore(&priv->lock, flags);
452 ch341_set_handshake(port->serial->dev, priv->mcr);
453 }
454
ch341_close(struct usb_serial_port * port)455 static void ch341_close(struct usb_serial_port *port)
456 {
457 usb_serial_generic_close(port);
458 usb_kill_urb(port->interrupt_in_urb);
459 }
460
461
462 /* open this device, set default parameters */
ch341_open(struct tty_struct * tty,struct usb_serial_port * port)463 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
464 {
465 struct ch341_private *priv = usb_get_serial_port_data(port);
466 int r;
467
468 if (tty)
469 ch341_set_termios(tty, port, NULL);
470
471 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
472 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
473 if (r) {
474 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
475 __func__, r);
476 return r;
477 }
478
479 r = ch341_get_status(port->serial->dev, priv);
480 if (r < 0) {
481 dev_err(&port->dev, "failed to read modem status: %d\n", r);
482 goto err_kill_interrupt_urb;
483 }
484
485 r = usb_serial_generic_open(tty, port);
486 if (r)
487 goto err_kill_interrupt_urb;
488
489 return 0;
490
491 err_kill_interrupt_urb:
492 usb_kill_urb(port->interrupt_in_urb);
493
494 return r;
495 }
496
497 /* Old_termios contains the original termios settings and
498 * tty->termios contains the new setting to be used.
499 */
ch341_set_termios(struct tty_struct * tty,struct usb_serial_port * port,struct ktermios * old_termios)500 static void ch341_set_termios(struct tty_struct *tty,
501 struct usb_serial_port *port, struct ktermios *old_termios)
502 {
503 struct ch341_private *priv = usb_get_serial_port_data(port);
504 unsigned baud_rate;
505 unsigned long flags;
506 u8 lcr;
507 int r;
508
509 /* redundant changes may cause the chip to lose bytes */
510 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
511 return;
512
513 baud_rate = tty_get_baud_rate(tty);
514
515 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
516
517 switch (C_CSIZE(tty)) {
518 case CS5:
519 lcr |= CH341_LCR_CS5;
520 break;
521 case CS6:
522 lcr |= CH341_LCR_CS6;
523 break;
524 case CS7:
525 lcr |= CH341_LCR_CS7;
526 break;
527 case CS8:
528 lcr |= CH341_LCR_CS8;
529 break;
530 }
531
532 if (C_PARENB(tty)) {
533 lcr |= CH341_LCR_ENABLE_PAR;
534 if (C_PARODD(tty) == 0)
535 lcr |= CH341_LCR_PAR_EVEN;
536 if (C_CMSPAR(tty))
537 lcr |= CH341_LCR_MARK_SPACE;
538 }
539
540 if (C_CSTOPB(tty))
541 lcr |= CH341_LCR_STOP_BITS_2;
542
543 if (baud_rate) {
544 priv->baud_rate = baud_rate;
545
546 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
547 priv->baud_rate, lcr);
548 if (r < 0 && old_termios) {
549 priv->baud_rate = tty_termios_baud_rate(old_termios);
550 tty_termios_copy_hw(&tty->termios, old_termios);
551 } else if (r == 0) {
552 priv->lcr = lcr;
553 }
554 }
555
556 spin_lock_irqsave(&priv->lock, flags);
557 if (C_BAUD(tty) == B0)
558 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
559 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
560 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
561 spin_unlock_irqrestore(&priv->lock, flags);
562
563 ch341_set_handshake(port->serial->dev, priv->mcr);
564 }
565
566 /*
567 * A subset of all CH34x devices don't support a real break condition and
568 * reading CH341_REG_BREAK fails (see also ch341_detect_quirks). This function
569 * simulates a break condition by lowering the baud rate to the minimum
570 * supported by the hardware upon enabling the break condition and sending
571 * a NUL byte.
572 *
573 * Incoming data is corrupted while the break condition is being simulated.
574 *
575 * Normally the duration of the break condition can be controlled individually
576 * by userspace using TIOCSBRK and TIOCCBRK or by passing an argument to
577 * TCSBRKP. Due to how the simulation is implemented the duration can't be
578 * controlled. The duration is always about (1s / 46bd * 9bit) = 196ms.
579 */
ch341_simulate_break(struct tty_struct * tty,int break_state)580 static void ch341_simulate_break(struct tty_struct *tty, int break_state)
581 {
582 struct usb_serial_port *port = tty->driver_data;
583 struct ch341_private *priv = usb_get_serial_port_data(port);
584 unsigned long now, delay;
585 int r;
586
587 if (break_state != 0) {
588 dev_dbg(&port->dev, "enter break state requested\n");
589
590 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
591 CH341_MIN_BPS,
592 CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8);
593 if (r < 0) {
594 dev_err(&port->dev,
595 "failed to change baud rate to %u: %d\n",
596 CH341_MIN_BPS, r);
597 goto restore;
598 }
599
600 r = tty_put_char(tty, '\0');
601 if (r < 0) {
602 dev_err(&port->dev,
603 "failed to write NUL byte for simulated break condition: %d\n",
604 r);
605 goto restore;
606 }
607
608 /*
609 * Compute expected transmission duration including safety
610 * margin. The original baud rate is only restored after the
611 * computed point in time.
612 *
613 * 11 bits = 1 start, 8 data, 1 stop, 1 margin
614 */
615 priv->break_end = jiffies + (11 * HZ / CH341_MIN_BPS);
616
617 return;
618 }
619
620 dev_dbg(&port->dev, "leave break state requested\n");
621
622 now = jiffies;
623
624 if (time_before(now, priv->break_end)) {
625 /* Wait until NUL byte is written */
626 delay = priv->break_end - now;
627 dev_dbg(&port->dev,
628 "wait %d ms while transmitting NUL byte at %u baud\n",
629 jiffies_to_msecs(delay), CH341_MIN_BPS);
630 schedule_timeout_interruptible(delay);
631 }
632
633 restore:
634 /* Restore original baud rate */
635 r = ch341_set_baudrate_lcr(port->serial->dev, priv, priv->baud_rate,
636 priv->lcr);
637 if (r < 0)
638 dev_err(&port->dev,
639 "restoring original baud rate of %u failed: %d\n",
640 priv->baud_rate, r);
641 }
642
ch341_break_ctl(struct tty_struct * tty,int break_state)643 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
644 {
645 const uint16_t ch341_break_reg =
646 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
647 struct usb_serial_port *port = tty->driver_data;
648 struct ch341_private *priv = usb_get_serial_port_data(port);
649 int r;
650 uint16_t reg_contents;
651 uint8_t *break_reg;
652
653 if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK) {
654 ch341_simulate_break(tty, break_state);
655 return;
656 }
657
658 break_reg = kmalloc(2, GFP_KERNEL);
659 if (!break_reg)
660 return;
661
662 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
663 ch341_break_reg, 0, break_reg, 2);
664 if (r < 0) {
665 dev_err(&port->dev, "%s - USB control read error (%d)\n",
666 __func__, r);
667 goto out;
668 }
669 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
670 __func__, break_reg[0], break_reg[1]);
671 if (break_state != 0) {
672 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
673 break_reg[0] &= ~CH341_NBREAK_BITS;
674 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
675 } else {
676 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
677 break_reg[0] |= CH341_NBREAK_BITS;
678 break_reg[1] |= CH341_LCR_ENABLE_TX;
679 }
680 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
681 __func__, break_reg[0], break_reg[1]);
682 reg_contents = get_unaligned_le16(break_reg);
683 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
684 ch341_break_reg, reg_contents);
685 if (r < 0)
686 dev_err(&port->dev, "%s - USB control write error (%d)\n",
687 __func__, r);
688 out:
689 kfree(break_reg);
690 }
691
ch341_tiocmset(struct tty_struct * tty,unsigned int set,unsigned int clear)692 static int ch341_tiocmset(struct tty_struct *tty,
693 unsigned int set, unsigned int clear)
694 {
695 struct usb_serial_port *port = tty->driver_data;
696 struct ch341_private *priv = usb_get_serial_port_data(port);
697 unsigned long flags;
698 u8 control;
699
700 spin_lock_irqsave(&priv->lock, flags);
701 if (set & TIOCM_RTS)
702 priv->mcr |= CH341_BIT_RTS;
703 if (set & TIOCM_DTR)
704 priv->mcr |= CH341_BIT_DTR;
705 if (clear & TIOCM_RTS)
706 priv->mcr &= ~CH341_BIT_RTS;
707 if (clear & TIOCM_DTR)
708 priv->mcr &= ~CH341_BIT_DTR;
709 control = priv->mcr;
710 spin_unlock_irqrestore(&priv->lock, flags);
711
712 return ch341_set_handshake(port->serial->dev, control);
713 }
714
ch341_update_status(struct usb_serial_port * port,unsigned char * data,size_t len)715 static void ch341_update_status(struct usb_serial_port *port,
716 unsigned char *data, size_t len)
717 {
718 struct ch341_private *priv = usb_get_serial_port_data(port);
719 struct tty_struct *tty;
720 unsigned long flags;
721 u8 status;
722 u8 delta;
723
724 if (len < 4)
725 return;
726
727 status = ~data[2] & CH341_BITS_MODEM_STAT;
728
729 spin_lock_irqsave(&priv->lock, flags);
730 delta = status ^ priv->msr;
731 priv->msr = status;
732 spin_unlock_irqrestore(&priv->lock, flags);
733
734 if (data[1] & CH341_MULT_STAT)
735 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
736
737 if (!delta)
738 return;
739
740 if (delta & CH341_BIT_CTS)
741 port->icount.cts++;
742 if (delta & CH341_BIT_DSR)
743 port->icount.dsr++;
744 if (delta & CH341_BIT_RI)
745 port->icount.rng++;
746 if (delta & CH341_BIT_DCD) {
747 port->icount.dcd++;
748 tty = tty_port_tty_get(&port->port);
749 if (tty) {
750 usb_serial_handle_dcd_change(port, tty,
751 status & CH341_BIT_DCD);
752 tty_kref_put(tty);
753 }
754 }
755
756 wake_up_interruptible(&port->port.delta_msr_wait);
757 }
758
ch341_read_int_callback(struct urb * urb)759 static void ch341_read_int_callback(struct urb *urb)
760 {
761 struct usb_serial_port *port = urb->context;
762 unsigned char *data = urb->transfer_buffer;
763 unsigned int len = urb->actual_length;
764 int status;
765
766 switch (urb->status) {
767 case 0:
768 /* success */
769 break;
770 case -ECONNRESET:
771 case -ENOENT:
772 case -ESHUTDOWN:
773 /* this urb is terminated, clean up */
774 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
775 __func__, urb->status);
776 return;
777 default:
778 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
779 __func__, urb->status);
780 goto exit;
781 }
782
783 usb_serial_debug_data(&port->dev, __func__, len, data);
784 ch341_update_status(port, data, len);
785 exit:
786 status = usb_submit_urb(urb, GFP_ATOMIC);
787 if (status) {
788 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
789 __func__, status);
790 }
791 }
792
ch341_tiocmget(struct tty_struct * tty)793 static int ch341_tiocmget(struct tty_struct *tty)
794 {
795 struct usb_serial_port *port = tty->driver_data;
796 struct ch341_private *priv = usb_get_serial_port_data(port);
797 unsigned long flags;
798 u8 mcr;
799 u8 status;
800 unsigned int result;
801
802 spin_lock_irqsave(&priv->lock, flags);
803 mcr = priv->mcr;
804 status = priv->msr;
805 spin_unlock_irqrestore(&priv->lock, flags);
806
807 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
808 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
809 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
810 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
811 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
812 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
813
814 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
815
816 return result;
817 }
818
ch341_reset_resume(struct usb_serial * serial)819 static int ch341_reset_resume(struct usb_serial *serial)
820 {
821 struct usb_serial_port *port = serial->port[0];
822 struct ch341_private *priv;
823 int ret;
824
825 priv = usb_get_serial_port_data(port);
826 if (!priv)
827 return 0;
828
829 /* reconfigure ch341 serial port after bus-reset */
830 ch341_configure(serial->dev, priv);
831
832 if (tty_port_initialized(&port->port)) {
833 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
834 if (ret) {
835 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
836 ret);
837 return ret;
838 }
839
840 ret = ch341_get_status(port->serial->dev, priv);
841 if (ret < 0) {
842 dev_err(&port->dev, "failed to read modem status: %d\n",
843 ret);
844 }
845 }
846
847 return usb_serial_generic_resume(serial);
848 }
849
850 static struct usb_serial_driver ch341_device = {
851 .driver = {
852 .owner = THIS_MODULE,
853 .name = "ch341-uart",
854 },
855 .id_table = id_table,
856 .num_ports = 1,
857 .open = ch341_open,
858 .dtr_rts = ch341_dtr_rts,
859 .carrier_raised = ch341_carrier_raised,
860 .close = ch341_close,
861 .set_termios = ch341_set_termios,
862 .break_ctl = ch341_break_ctl,
863 .tiocmget = ch341_tiocmget,
864 .tiocmset = ch341_tiocmset,
865 .tiocmiwait = usb_serial_generic_tiocmiwait,
866 .read_int_callback = ch341_read_int_callback,
867 .port_probe = ch341_port_probe,
868 .port_remove = ch341_port_remove,
869 .reset_resume = ch341_reset_resume,
870 };
871
872 static struct usb_serial_driver * const serial_drivers[] = {
873 &ch341_device, NULL
874 };
875
876 module_usb_serial_driver(serial_drivers, id_table);
877
878 MODULE_LICENSE("GPL v2");
879