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 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(dev, usb_rcvctrlpipe(dev, 0), request,
138 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
139 value, index, buf, bufsize, DEFAULT_TIMEOUT);
140 if (r < (int)bufsize) {
141 if (r >= 0) {
142 dev_err(&dev->dev,
143 "short control message received (%d < %u)\n",
144 r, bufsize);
145 r = -EIO;
146 }
147
148 dev_err(&dev->dev, "failed to receive control message: %d\n",
149 r);
150 return r;
151 }
152
153 return 0;
154 }
155
156 #define CH341_CLKRATE 48000000
157 #define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
158 #define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
159
160 static const speed_t ch341_min_rates[] = {
161 CH341_MIN_RATE(0),
162 CH341_MIN_RATE(1),
163 CH341_MIN_RATE(2),
164 CH341_MIN_RATE(3),
165 };
166
167 /* Supported range is 46 to 3000000 bps. */
168 #define CH341_MIN_BPS DIV_ROUND_UP(CH341_CLKRATE, CH341_CLK_DIV(0, 0) * 256)
169 #define CH341_MAX_BPS (CH341_CLKRATE / (CH341_CLK_DIV(3, 0) * 2))
170
171 /*
172 * The device line speed is given by the following equation:
173 *
174 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
175 *
176 * 0 <= ps <= 3,
177 * 0 <= fact <= 1,
178 * 2 <= div <= 256 if fact = 0, or
179 * 9 <= div <= 256 if fact = 1
180 */
ch341_get_divisor(struct ch341_private * priv,speed_t speed)181 static int ch341_get_divisor(struct ch341_private *priv, speed_t speed)
182 {
183 unsigned int fact, div, clk_div;
184 bool force_fact0 = false;
185 int ps;
186
187 /*
188 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
189 * sanity checks below redundant.
190 */
191 speed = clamp_val(speed, CH341_MIN_BPS, CH341_MAX_BPS);
192
193 /*
194 * Start with highest possible base clock (fact = 1) that will give a
195 * divisor strictly less than 512.
196 */
197 fact = 1;
198 for (ps = 3; ps >= 0; ps--) {
199 if (speed > ch341_min_rates[ps])
200 break;
201 }
202
203 if (ps < 0)
204 return -EINVAL;
205
206 /* Determine corresponding divisor, rounding down. */
207 clk_div = CH341_CLK_DIV(ps, fact);
208 div = CH341_CLKRATE / (clk_div * speed);
209
210 /* Some devices require a lower base clock if ps < 3. */
211 if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER))
212 force_fact0 = true;
213
214 /* Halve base clock (fact = 0) if required. */
215 if (div < 9 || div > 255 || force_fact0) {
216 div /= 2;
217 clk_div *= 2;
218 fact = 0;
219 }
220
221 if (div < 2)
222 return -EINVAL;
223
224 /*
225 * Pick next divisor if resulting rate is closer to the requested one,
226 * scale up to avoid rounding errors on low rates.
227 */
228 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
229 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
230 div++;
231
232 /*
233 * Prefer lower base clock (fact = 0) if even divisor.
234 *
235 * Note that this makes the receiver more tolerant to errors.
236 */
237 if (fact == 1 && div % 2 == 0) {
238 div /= 2;
239 fact = 0;
240 }
241
242 return (0x100 - div) << 8 | fact << 2 | ps;
243 }
244
ch341_set_baudrate_lcr(struct usb_device * dev,struct ch341_private * priv,speed_t baud_rate,u8 lcr)245 static int ch341_set_baudrate_lcr(struct usb_device *dev,
246 struct ch341_private *priv,
247 speed_t baud_rate, u8 lcr)
248 {
249 int val;
250 int r;
251
252 if (!baud_rate)
253 return -EINVAL;
254
255 val = ch341_get_divisor(priv, baud_rate);
256 if (val < 0)
257 return -EINVAL;
258
259 /*
260 * CH341A buffers data until a full endpoint-size packet (32 bytes)
261 * has been received unless bit 7 is set.
262 *
263 * At least one device with version 0x27 appears to have this bit
264 * inverted.
265 */
266 if (priv->version > 0x27)
267 val |= BIT(7);
268
269 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
270 CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
271 val);
272 if (r)
273 return r;
274
275 /*
276 * Chip versions before version 0x30 as read using
277 * CH341_REQ_READ_VERSION used separate registers for line control
278 * (stop bits, parity and word length). Version 0x30 and above use
279 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
280 */
281 if (priv->version < 0x30)
282 return 0;
283
284 r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
285 CH341_REG_LCR2 << 8 | CH341_REG_LCR, lcr);
286 if (r)
287 return r;
288
289 return r;
290 }
291
ch341_set_handshake(struct usb_device * dev,u8 control)292 static int ch341_set_handshake(struct usb_device *dev, u8 control)
293 {
294 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
295 }
296
ch341_get_status(struct usb_device * dev,struct ch341_private * priv)297 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
298 {
299 const unsigned int size = 2;
300 char *buffer;
301 int r;
302 unsigned long flags;
303
304 buffer = kmalloc(size, GFP_KERNEL);
305 if (!buffer)
306 return -ENOMEM;
307
308 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
309 if (r < 0)
310 goto out;
311
312 spin_lock_irqsave(&priv->lock, flags);
313 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
314 spin_unlock_irqrestore(&priv->lock, flags);
315
316 out: kfree(buffer);
317 return r;
318 }
319
320 /* -------------------------------------------------------------------------- */
321
ch341_configure(struct usb_device * dev,struct ch341_private * priv)322 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
323 {
324 const unsigned int size = 2;
325 char *buffer;
326 int r;
327
328 buffer = kmalloc(size, GFP_KERNEL);
329 if (!buffer)
330 return -ENOMEM;
331
332 /* expect two bytes 0x27 0x00 */
333 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
334 if (r < 0)
335 goto out;
336
337 priv->version = buffer[0];
338 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", priv->version);
339
340 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
341 if (r < 0)
342 goto out;
343
344 r = ch341_set_baudrate_lcr(dev, priv, priv->baud_rate, priv->lcr);
345 if (r < 0)
346 goto out;
347
348 r = ch341_set_handshake(dev, priv->mcr);
349
350 out: kfree(buffer);
351 return r;
352 }
353
ch341_detect_quirks(struct usb_serial_port * port)354 static int ch341_detect_quirks(struct usb_serial_port *port)
355 {
356 struct ch341_private *priv = usb_get_serial_port_data(port);
357 struct usb_device *udev = port->serial->dev;
358 const unsigned int size = 2;
359 unsigned long quirks = 0;
360 char *buffer;
361 int r;
362
363 buffer = kmalloc(size, GFP_KERNEL);
364 if (!buffer)
365 return -ENOMEM;
366
367 /*
368 * A subset of CH34x devices does not support all features. The
369 * prescaler is limited and there is no support for sending a RS232
370 * break condition. A read failure when trying to set up the latter is
371 * used to detect these devices.
372 */
373 r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG,
374 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
375 CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT);
376 if (r == -EPIPE) {
377 dev_info(&port->dev, "break control not supported, using simulated break\n");
378 quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK;
379 r = 0;
380 goto out;
381 }
382
383 if (r != size) {
384 if (r >= 0)
385 r = -EIO;
386 dev_err(&port->dev, "failed to read break control: %d\n", r);
387 goto out;
388 }
389
390 r = 0;
391 out:
392 kfree(buffer);
393
394 if (quirks) {
395 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
396 priv->quirks |= quirks;
397 }
398
399 return r;
400 }
401
ch341_port_probe(struct usb_serial_port * port)402 static int ch341_port_probe(struct usb_serial_port *port)
403 {
404 struct ch341_private *priv;
405 int r;
406
407 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
408 if (!priv)
409 return -ENOMEM;
410
411 spin_lock_init(&priv->lock);
412 priv->baud_rate = DEFAULT_BAUD_RATE;
413 /*
414 * Some CH340 devices appear unable to change the initial LCR
415 * settings, so set a sane 8N1 default.
416 */
417 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
418
419 r = ch341_configure(port->serial->dev, priv);
420 if (r < 0)
421 goto error;
422
423 usb_set_serial_port_data(port, priv);
424
425 r = ch341_detect_quirks(port);
426 if (r < 0)
427 goto error;
428
429 return 0;
430
431 error: kfree(priv);
432 return r;
433 }
434
ch341_port_remove(struct usb_serial_port * port)435 static int ch341_port_remove(struct usb_serial_port *port)
436 {
437 struct ch341_private *priv;
438
439 priv = usb_get_serial_port_data(port);
440 kfree(priv);
441
442 return 0;
443 }
444
ch341_carrier_raised(struct usb_serial_port * port)445 static int ch341_carrier_raised(struct usb_serial_port *port)
446 {
447 struct ch341_private *priv = usb_get_serial_port_data(port);
448 if (priv->msr & CH341_BIT_DCD)
449 return 1;
450 return 0;
451 }
452
ch341_dtr_rts(struct usb_serial_port * port,int on)453 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
454 {
455 struct ch341_private *priv = usb_get_serial_port_data(port);
456 unsigned long flags;
457
458 /* drop DTR and RTS */
459 spin_lock_irqsave(&priv->lock, flags);
460 if (on)
461 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
462 else
463 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
464 spin_unlock_irqrestore(&priv->lock, flags);
465 ch341_set_handshake(port->serial->dev, priv->mcr);
466 }
467
ch341_close(struct usb_serial_port * port)468 static void ch341_close(struct usb_serial_port *port)
469 {
470 usb_serial_generic_close(port);
471 usb_kill_urb(port->interrupt_in_urb);
472 }
473
474
475 /* open this device, set default parameters */
ch341_open(struct tty_struct * tty,struct usb_serial_port * port)476 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
477 {
478 struct ch341_private *priv = usb_get_serial_port_data(port);
479 int r;
480
481 if (tty)
482 ch341_set_termios(tty, port, NULL);
483
484 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
485 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
486 if (r) {
487 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
488 __func__, r);
489 return r;
490 }
491
492 r = ch341_get_status(port->serial->dev, priv);
493 if (r < 0) {
494 dev_err(&port->dev, "failed to read modem status: %d\n", r);
495 goto err_kill_interrupt_urb;
496 }
497
498 r = usb_serial_generic_open(tty, port);
499 if (r)
500 goto err_kill_interrupt_urb;
501
502 return 0;
503
504 err_kill_interrupt_urb:
505 usb_kill_urb(port->interrupt_in_urb);
506
507 return r;
508 }
509
510 /* Old_termios contains the original termios settings and
511 * tty->termios contains the new setting to be used.
512 */
ch341_set_termios(struct tty_struct * tty,struct usb_serial_port * port,struct ktermios * old_termios)513 static void ch341_set_termios(struct tty_struct *tty,
514 struct usb_serial_port *port, struct ktermios *old_termios)
515 {
516 struct ch341_private *priv = usb_get_serial_port_data(port);
517 unsigned baud_rate;
518 unsigned long flags;
519 u8 lcr;
520 int r;
521
522 /* redundant changes may cause the chip to lose bytes */
523 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
524 return;
525
526 baud_rate = tty_get_baud_rate(tty);
527
528 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
529
530 switch (C_CSIZE(tty)) {
531 case CS5:
532 lcr |= CH341_LCR_CS5;
533 break;
534 case CS6:
535 lcr |= CH341_LCR_CS6;
536 break;
537 case CS7:
538 lcr |= CH341_LCR_CS7;
539 break;
540 case CS8:
541 lcr |= CH341_LCR_CS8;
542 break;
543 }
544
545 if (C_PARENB(tty)) {
546 lcr |= CH341_LCR_ENABLE_PAR;
547 if (C_PARODD(tty) == 0)
548 lcr |= CH341_LCR_PAR_EVEN;
549 if (C_CMSPAR(tty))
550 lcr |= CH341_LCR_MARK_SPACE;
551 }
552
553 if (C_CSTOPB(tty))
554 lcr |= CH341_LCR_STOP_BITS_2;
555
556 if (baud_rate) {
557 priv->baud_rate = baud_rate;
558
559 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
560 priv->baud_rate, lcr);
561 if (r < 0 && old_termios) {
562 priv->baud_rate = tty_termios_baud_rate(old_termios);
563 tty_termios_copy_hw(&tty->termios, old_termios);
564 } else if (r == 0) {
565 priv->lcr = lcr;
566 }
567 }
568
569 spin_lock_irqsave(&priv->lock, flags);
570 if (C_BAUD(tty) == B0)
571 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
572 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
573 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
574 spin_unlock_irqrestore(&priv->lock, flags);
575
576 ch341_set_handshake(port->serial->dev, priv->mcr);
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 */
ch341_simulate_break(struct tty_struct * tty,int break_state)593 static void 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;
599
600 if (break_state != 0) {
601 dev_dbg(&port->dev, "enter break state requested\n");
602
603 r = ch341_set_baudrate_lcr(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, '\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;
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(delay);
644 }
645
646 restore:
647 /* Restore original baud rate */
648 r = ch341_set_baudrate_lcr(port->serial->dev, priv, priv->baud_rate,
649 priv->lcr);
650 if (r < 0)
651 dev_err(&port->dev,
652 "restoring original baud rate of %u failed: %d\n",
653 priv->baud_rate, r);
654 }
655
ch341_break_ctl(struct tty_struct * tty,int break_state)656 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
657 {
658 const uint16_t ch341_break_reg =
659 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
660 struct usb_serial_port *port = tty->driver_data;
661 struct ch341_private *priv = usb_get_serial_port_data(port);
662 int r;
663 uint16_t reg_contents;
664 uint8_t *break_reg;
665
666 if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK) {
667 ch341_simulate_break(tty, break_state);
668 return;
669 }
670
671 break_reg = kmalloc(2, GFP_KERNEL);
672 if (!break_reg)
673 return;
674
675 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
676 ch341_break_reg, 0, break_reg, 2);
677 if (r < 0) {
678 dev_err(&port->dev, "%s - USB control read error (%d)\n",
679 __func__, r);
680 goto out;
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(break_reg);
696 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
697 ch341_break_reg, reg_contents);
698 if (r < 0)
699 dev_err(&port->dev, "%s - USB control write error (%d)\n",
700 __func__, r);
701 out:
702 kfree(break_reg);
703 }
704
ch341_tiocmset(struct tty_struct * tty,unsigned int set,unsigned int clear)705 static int ch341_tiocmset(struct tty_struct *tty,
706 unsigned int set, unsigned int clear)
707 {
708 struct usb_serial_port *port = tty->driver_data;
709 struct ch341_private *priv = usb_get_serial_port_data(port);
710 unsigned long flags;
711 u8 control;
712
713 spin_lock_irqsave(&priv->lock, flags);
714 if (set & TIOCM_RTS)
715 priv->mcr |= CH341_BIT_RTS;
716 if (set & TIOCM_DTR)
717 priv->mcr |= CH341_BIT_DTR;
718 if (clear & TIOCM_RTS)
719 priv->mcr &= ~CH341_BIT_RTS;
720 if (clear & TIOCM_DTR)
721 priv->mcr &= ~CH341_BIT_DTR;
722 control = priv->mcr;
723 spin_unlock_irqrestore(&priv->lock, flags);
724
725 return ch341_set_handshake(port->serial->dev, control);
726 }
727
ch341_update_status(struct usb_serial_port * port,unsigned char * data,size_t len)728 static void ch341_update_status(struct usb_serial_port *port,
729 unsigned char *data, size_t len)
730 {
731 struct ch341_private *priv = usb_get_serial_port_data(port);
732 struct tty_struct *tty;
733 unsigned long flags;
734 u8 status;
735 u8 delta;
736
737 if (len < 4)
738 return;
739
740 status = ~data[2] & CH341_BITS_MODEM_STAT;
741
742 spin_lock_irqsave(&priv->lock, flags);
743 delta = status ^ priv->msr;
744 priv->msr = status;
745 spin_unlock_irqrestore(&priv->lock, flags);
746
747 if (data[1] & CH341_MULT_STAT)
748 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
749
750 if (!delta)
751 return;
752
753 if (delta & CH341_BIT_CTS)
754 port->icount.cts++;
755 if (delta & CH341_BIT_DSR)
756 port->icount.dsr++;
757 if (delta & CH341_BIT_RI)
758 port->icount.rng++;
759 if (delta & CH341_BIT_DCD) {
760 port->icount.dcd++;
761 tty = tty_port_tty_get(&port->port);
762 if (tty) {
763 usb_serial_handle_dcd_change(port, tty,
764 status & CH341_BIT_DCD);
765 tty_kref_put(tty);
766 }
767 }
768
769 wake_up_interruptible(&port->port.delta_msr_wait);
770 }
771
ch341_read_int_callback(struct urb * urb)772 static void ch341_read_int_callback(struct urb *urb)
773 {
774 struct usb_serial_port *port = urb->context;
775 unsigned char *data = urb->transfer_buffer;
776 unsigned int len = urb->actual_length;
777 int status;
778
779 switch (urb->status) {
780 case 0:
781 /* success */
782 break;
783 case -ECONNRESET:
784 case -ENOENT:
785 case -ESHUTDOWN:
786 /* this urb is terminated, clean up */
787 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
788 __func__, urb->status);
789 return;
790 default:
791 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
792 __func__, urb->status);
793 goto exit;
794 }
795
796 usb_serial_debug_data(&port->dev, __func__, len, data);
797 ch341_update_status(port, data, len);
798 exit:
799 status = usb_submit_urb(urb, GFP_ATOMIC);
800 if (status) {
801 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
802 __func__, status);
803 }
804 }
805
ch341_tiocmget(struct tty_struct * tty)806 static int ch341_tiocmget(struct tty_struct *tty)
807 {
808 struct usb_serial_port *port = tty->driver_data;
809 struct ch341_private *priv = usb_get_serial_port_data(port);
810 unsigned long flags;
811 u8 mcr;
812 u8 status;
813 unsigned int result;
814
815 spin_lock_irqsave(&priv->lock, flags);
816 mcr = priv->mcr;
817 status = priv->msr;
818 spin_unlock_irqrestore(&priv->lock, flags);
819
820 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
821 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
822 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
823 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
824 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
825 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
826
827 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
828
829 return result;
830 }
831
ch341_reset_resume(struct usb_serial * serial)832 static int ch341_reset_resume(struct usb_serial *serial)
833 {
834 struct usb_serial_port *port = serial->port[0];
835 struct ch341_private *priv;
836 int ret;
837
838 priv = usb_get_serial_port_data(port);
839 if (!priv)
840 return 0;
841
842 /* reconfigure ch341 serial port after bus-reset */
843 ch341_configure(serial->dev, priv);
844
845 if (tty_port_initialized(&port->port)) {
846 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
847 if (ret) {
848 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
849 ret);
850 return ret;
851 }
852
853 ret = ch341_get_status(port->serial->dev, priv);
854 if (ret < 0) {
855 dev_err(&port->dev, "failed to read modem status: %d\n",
856 ret);
857 }
858 }
859
860 return usb_serial_generic_resume(serial);
861 }
862
863 static struct usb_serial_driver ch341_device = {
864 .driver = {
865 .owner = THIS_MODULE,
866 .name = "ch341-uart",
867 },
868 .id_table = id_table,
869 .num_ports = 1,
870 .open = ch341_open,
871 .dtr_rts = ch341_dtr_rts,
872 .carrier_raised = ch341_carrier_raised,
873 .close = ch341_close,
874 .set_termios = ch341_set_termios,
875 .break_ctl = ch341_break_ctl,
876 .tiocmget = ch341_tiocmget,
877 .tiocmset = ch341_tiocmset,
878 .tiocmiwait = usb_serial_generic_tiocmiwait,
879 .read_int_callback = ch341_read_int_callback,
880 .port_probe = ch341_port_probe,
881 .port_remove = ch341_port_remove,
882 .reset_resume = ch341_reset_resume,
883 };
884
885 static struct usb_serial_driver * const serial_drivers[] = {
886 &ch341_device, NULL
887 };
888
889 module_usb_serial_driver(serial_drivers, id_table);
890
891 MODULE_LICENSE("GPL v2");
892