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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