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 void 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
ch341_carrier_raised(struct usb_serial_port * port)443 static int ch341_carrier_raised(struct usb_serial_port *port)
444 {
445 struct ch341_private *priv = usb_get_serial_port_data(port);
446 if (priv->msr & CH341_BIT_DCD)
447 return 1;
448 return 0;
449 }
450
ch341_dtr_rts(struct usb_serial_port * port,int on)451 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
452 {
453 struct ch341_private *priv = usb_get_serial_port_data(port);
454 unsigned long flags;
455
456 /* drop DTR and RTS */
457 spin_lock_irqsave(&priv->lock, flags);
458 if (on)
459 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
460 else
461 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
462 spin_unlock_irqrestore(&priv->lock, flags);
463 ch341_set_handshake(port->serial->dev, priv->mcr);
464 }
465
ch341_close(struct usb_serial_port * port)466 static void ch341_close(struct usb_serial_port *port)
467 {
468 usb_serial_generic_close(port);
469 usb_kill_urb(port->interrupt_in_urb);
470 }
471
472
473 /* open this device, set default parameters */
ch341_open(struct tty_struct * tty,struct usb_serial_port * port)474 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
475 {
476 struct ch341_private *priv = usb_get_serial_port_data(port);
477 int r;
478
479 if (tty)
480 ch341_set_termios(tty, port, NULL);
481
482 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
483 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
484 if (r) {
485 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
486 __func__, r);
487 return r;
488 }
489
490 r = ch341_get_status(port->serial->dev, priv);
491 if (r < 0) {
492 dev_err(&port->dev, "failed to read modem status: %d\n", r);
493 goto err_kill_interrupt_urb;
494 }
495
496 r = usb_serial_generic_open(tty, port);
497 if (r)
498 goto err_kill_interrupt_urb;
499
500 return 0;
501
502 err_kill_interrupt_urb:
503 usb_kill_urb(port->interrupt_in_urb);
504
505 return r;
506 }
507
508 /* Old_termios contains the original termios settings and
509 * tty->termios contains the new setting to be used.
510 */
ch341_set_termios(struct tty_struct * tty,struct usb_serial_port * port,struct ktermios * old_termios)511 static void ch341_set_termios(struct tty_struct *tty,
512 struct usb_serial_port *port, struct ktermios *old_termios)
513 {
514 struct ch341_private *priv = usb_get_serial_port_data(port);
515 unsigned baud_rate;
516 unsigned long flags;
517 u8 lcr;
518 int r;
519
520 /* redundant changes may cause the chip to lose bytes */
521 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
522 return;
523
524 baud_rate = tty_get_baud_rate(tty);
525
526 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
527
528 switch (C_CSIZE(tty)) {
529 case CS5:
530 lcr |= CH341_LCR_CS5;
531 break;
532 case CS6:
533 lcr |= CH341_LCR_CS6;
534 break;
535 case CS7:
536 lcr |= CH341_LCR_CS7;
537 break;
538 case CS8:
539 lcr |= CH341_LCR_CS8;
540 break;
541 }
542
543 if (C_PARENB(tty)) {
544 lcr |= CH341_LCR_ENABLE_PAR;
545 if (C_PARODD(tty) == 0)
546 lcr |= CH341_LCR_PAR_EVEN;
547 if (C_CMSPAR(tty))
548 lcr |= CH341_LCR_MARK_SPACE;
549 }
550
551 if (C_CSTOPB(tty))
552 lcr |= CH341_LCR_STOP_BITS_2;
553
554 if (baud_rate) {
555 priv->baud_rate = baud_rate;
556
557 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
558 priv->baud_rate, lcr);
559 if (r < 0 && old_termios) {
560 priv->baud_rate = tty_termios_baud_rate(old_termios);
561 tty_termios_copy_hw(&tty->termios, old_termios);
562 } else if (r == 0) {
563 priv->lcr = lcr;
564 }
565 }
566
567 spin_lock_irqsave(&priv->lock, flags);
568 if (C_BAUD(tty) == B0)
569 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
570 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
571 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
572 spin_unlock_irqrestore(&priv->lock, flags);
573
574 ch341_set_handshake(port->serial->dev, priv->mcr);
575 }
576
577 /*
578 * A subset of all CH34x devices don't support a real break condition and
579 * reading CH341_REG_BREAK fails (see also ch341_detect_quirks). This function
580 * simulates a break condition by lowering the baud rate to the minimum
581 * supported by the hardware upon enabling the break condition and sending
582 * a NUL byte.
583 *
584 * Incoming data is corrupted while the break condition is being simulated.
585 *
586 * Normally the duration of the break condition can be controlled individually
587 * by userspace using TIOCSBRK and TIOCCBRK or by passing an argument to
588 * TCSBRKP. Due to how the simulation is implemented the duration can't be
589 * controlled. The duration is always about (1s / 46bd * 9bit) = 196ms.
590 */
ch341_simulate_break(struct tty_struct * tty,int break_state)591 static void ch341_simulate_break(struct tty_struct *tty, int break_state)
592 {
593 struct usb_serial_port *port = tty->driver_data;
594 struct ch341_private *priv = usb_get_serial_port_data(port);
595 unsigned long now, delay;
596 int r;
597
598 if (break_state != 0) {
599 dev_dbg(&port->dev, "enter break state requested\n");
600
601 r = ch341_set_baudrate_lcr(port->serial->dev, priv,
602 CH341_MIN_BPS,
603 CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8);
604 if (r < 0) {
605 dev_err(&port->dev,
606 "failed to change baud rate to %u: %d\n",
607 CH341_MIN_BPS, r);
608 goto restore;
609 }
610
611 r = tty_put_char(tty, '\0');
612 if (r < 0) {
613 dev_err(&port->dev,
614 "failed to write NUL byte for simulated break condition: %d\n",
615 r);
616 goto restore;
617 }
618
619 /*
620 * Compute expected transmission duration including safety
621 * margin. The original baud rate is only restored after the
622 * computed point in time.
623 *
624 * 11 bits = 1 start, 8 data, 1 stop, 1 margin
625 */
626 priv->break_end = jiffies + (11 * HZ / CH341_MIN_BPS);
627
628 return;
629 }
630
631 dev_dbg(&port->dev, "leave break state requested\n");
632
633 now = jiffies;
634
635 if (time_before(now, priv->break_end)) {
636 /* Wait until NUL byte is written */
637 delay = priv->break_end - now;
638 dev_dbg(&port->dev,
639 "wait %d ms while transmitting NUL byte at %u baud\n",
640 jiffies_to_msecs(delay), CH341_MIN_BPS);
641 schedule_timeout_interruptible(delay);
642 }
643
644 restore:
645 /* Restore original baud rate */
646 r = ch341_set_baudrate_lcr(port->serial->dev, priv, priv->baud_rate,
647 priv->lcr);
648 if (r < 0)
649 dev_err(&port->dev,
650 "restoring original baud rate of %u failed: %d\n",
651 priv->baud_rate, r);
652 }
653
ch341_break_ctl(struct tty_struct * tty,int break_state)654 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
655 {
656 const uint16_t ch341_break_reg =
657 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
658 struct usb_serial_port *port = tty->driver_data;
659 struct ch341_private *priv = usb_get_serial_port_data(port);
660 int r;
661 uint16_t reg_contents;
662 uint8_t *break_reg;
663
664 if (priv->quirks & CH341_QUIRK_SIMULATE_BREAK) {
665 ch341_simulate_break(tty, break_state);
666 return;
667 }
668
669 break_reg = kmalloc(2, GFP_KERNEL);
670 if (!break_reg)
671 return;
672
673 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
674 ch341_break_reg, 0, break_reg, 2);
675 if (r < 0) {
676 dev_err(&port->dev, "%s - USB control read error (%d)\n",
677 __func__, r);
678 goto out;
679 }
680 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
681 __func__, break_reg[0], break_reg[1]);
682 if (break_state != 0) {
683 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
684 break_reg[0] &= ~CH341_NBREAK_BITS;
685 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
686 } else {
687 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
688 break_reg[0] |= CH341_NBREAK_BITS;
689 break_reg[1] |= CH341_LCR_ENABLE_TX;
690 }
691 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
692 __func__, break_reg[0], break_reg[1]);
693 reg_contents = get_unaligned_le16(break_reg);
694 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
695 ch341_break_reg, reg_contents);
696 if (r < 0)
697 dev_err(&port->dev, "%s - USB control write error (%d)\n",
698 __func__, r);
699 out:
700 kfree(break_reg);
701 }
702
ch341_tiocmset(struct tty_struct * tty,unsigned int set,unsigned int clear)703 static int ch341_tiocmset(struct tty_struct *tty,
704 unsigned int set, unsigned int clear)
705 {
706 struct usb_serial_port *port = tty->driver_data;
707 struct ch341_private *priv = usb_get_serial_port_data(port);
708 unsigned long flags;
709 u8 control;
710
711 spin_lock_irqsave(&priv->lock, flags);
712 if (set & TIOCM_RTS)
713 priv->mcr |= CH341_BIT_RTS;
714 if (set & TIOCM_DTR)
715 priv->mcr |= CH341_BIT_DTR;
716 if (clear & TIOCM_RTS)
717 priv->mcr &= ~CH341_BIT_RTS;
718 if (clear & TIOCM_DTR)
719 priv->mcr &= ~CH341_BIT_DTR;
720 control = priv->mcr;
721 spin_unlock_irqrestore(&priv->lock, flags);
722
723 return ch341_set_handshake(port->serial->dev, control);
724 }
725
ch341_update_status(struct usb_serial_port * port,unsigned char * data,size_t len)726 static void ch341_update_status(struct usb_serial_port *port,
727 unsigned char *data, size_t len)
728 {
729 struct ch341_private *priv = usb_get_serial_port_data(port);
730 struct tty_struct *tty;
731 unsigned long flags;
732 u8 status;
733 u8 delta;
734
735 if (len < 4)
736 return;
737
738 status = ~data[2] & CH341_BITS_MODEM_STAT;
739
740 spin_lock_irqsave(&priv->lock, flags);
741 delta = status ^ priv->msr;
742 priv->msr = status;
743 spin_unlock_irqrestore(&priv->lock, flags);
744
745 if (data[1] & CH341_MULT_STAT)
746 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
747
748 if (!delta)
749 return;
750
751 if (delta & CH341_BIT_CTS)
752 port->icount.cts++;
753 if (delta & CH341_BIT_DSR)
754 port->icount.dsr++;
755 if (delta & CH341_BIT_RI)
756 port->icount.rng++;
757 if (delta & CH341_BIT_DCD) {
758 port->icount.dcd++;
759 tty = tty_port_tty_get(&port->port);
760 if (tty) {
761 usb_serial_handle_dcd_change(port, tty,
762 status & CH341_BIT_DCD);
763 tty_kref_put(tty);
764 }
765 }
766
767 wake_up_interruptible(&port->port.delta_msr_wait);
768 }
769
ch341_read_int_callback(struct urb * urb)770 static void ch341_read_int_callback(struct urb *urb)
771 {
772 struct usb_serial_port *port = urb->context;
773 unsigned char *data = urb->transfer_buffer;
774 unsigned int len = urb->actual_length;
775 int status;
776
777 switch (urb->status) {
778 case 0:
779 /* success */
780 break;
781 case -ECONNRESET:
782 case -ENOENT:
783 case -ESHUTDOWN:
784 /* this urb is terminated, clean up */
785 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
786 __func__, urb->status);
787 return;
788 default:
789 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
790 __func__, urb->status);
791 goto exit;
792 }
793
794 usb_serial_debug_data(&port->dev, __func__, len, data);
795 ch341_update_status(port, data, len);
796 exit:
797 status = usb_submit_urb(urb, GFP_ATOMIC);
798 if (status) {
799 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
800 __func__, status);
801 }
802 }
803
ch341_tiocmget(struct tty_struct * tty)804 static int ch341_tiocmget(struct tty_struct *tty)
805 {
806 struct usb_serial_port *port = tty->driver_data;
807 struct ch341_private *priv = usb_get_serial_port_data(port);
808 unsigned long flags;
809 u8 mcr;
810 u8 status;
811 unsigned int result;
812
813 spin_lock_irqsave(&priv->lock, flags);
814 mcr = priv->mcr;
815 status = priv->msr;
816 spin_unlock_irqrestore(&priv->lock, flags);
817
818 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
819 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
820 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
821 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
822 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
823 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
824
825 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
826
827 return result;
828 }
829
ch341_reset_resume(struct usb_serial * serial)830 static int ch341_reset_resume(struct usb_serial *serial)
831 {
832 struct usb_serial_port *port = serial->port[0];
833 struct ch341_private *priv;
834 int ret;
835
836 priv = usb_get_serial_port_data(port);
837 if (!priv)
838 return 0;
839
840 /* reconfigure ch341 serial port after bus-reset */
841 ch341_configure(serial->dev, priv);
842
843 if (tty_port_initialized(&port->port)) {
844 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
845 if (ret) {
846 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
847 ret);
848 return ret;
849 }
850
851 ret = ch341_get_status(port->serial->dev, priv);
852 if (ret < 0) {
853 dev_err(&port->dev, "failed to read modem status: %d\n",
854 ret);
855 }
856 }
857
858 return usb_serial_generic_resume(serial);
859 }
860
861 static struct usb_serial_driver ch341_device = {
862 .driver = {
863 .owner = THIS_MODULE,
864 .name = "ch341-uart",
865 },
866 .id_table = id_table,
867 .num_ports = 1,
868 .open = ch341_open,
869 .dtr_rts = ch341_dtr_rts,
870 .carrier_raised = ch341_carrier_raised,
871 .close = ch341_close,
872 .set_termios = ch341_set_termios,
873 .break_ctl = ch341_break_ctl,
874 .tiocmget = ch341_tiocmget,
875 .tiocmset = ch341_tiocmset,
876 .tiocmiwait = usb_serial_generic_tiocmiwait,
877 .read_int_callback = ch341_read_int_callback,
878 .port_probe = ch341_port_probe,
879 .port_remove = ch341_port_remove,
880 .reset_resume = ch341_reset_resume,
881 };
882
883 static struct usb_serial_driver * const serial_drivers[] = {
884 &ch341_device, NULL
885 };
886
887 module_usb_serial_driver(serial_drivers, id_table);
888
889 MODULE_LICENSE("GPL v2");
890