xref: /linux/drivers/usb/serial/mct_u232.c (revision d2912cb15bdda8ba4a5dd73396ad62641af2f520)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * MCT (Magic Control Technology Corp.) USB RS232 Converter Driver
4  *
5  *   Copyright (C) 2000 Wolfgang Grandegger (wolfgang@ces.ch)
6  *
7  * This program is largely derived from the Belkin USB Serial Adapter Driver
8  * (see belkin_sa.[ch]). All of the information about the device was acquired
9  * by using SniffUSB on Windows98. For technical details see mct_u232.h.
10  *
11  * William G. Greathouse and Greg Kroah-Hartman provided great help on how to
12  * do the reverse engineering and how to write a USB serial device driver.
13  *
14  * TO BE DONE, TO BE CHECKED:
15  *   DTR/RTS signal handling may be incomplete or incorrect. I have mainly
16  *   implemented what I have seen with SniffUSB or found in belkin_sa.c.
17  *   For further TODOs check also belkin_sa.c.
18  */
19 
20 #include <linux/kernel.h>
21 #include <linux/errno.h>
22 #include <linux/slab.h>
23 #include <linux/tty.h>
24 #include <linux/tty_driver.h>
25 #include <linux/tty_flip.h>
26 #include <linux/module.h>
27 #include <linux/spinlock.h>
28 #include <linux/uaccess.h>
29 #include <asm/unaligned.h>
30 #include <linux/usb.h>
31 #include <linux/usb/serial.h>
32 #include <linux/serial.h>
33 #include "mct_u232.h"
34 
35 #define DRIVER_AUTHOR "Wolfgang Grandegger <wolfgang@ces.ch>"
36 #define DRIVER_DESC "Magic Control Technology USB-RS232 converter driver"
37 
38 /*
39  * Function prototypes
40  */
41 static int  mct_u232_port_probe(struct usb_serial_port *port);
42 static int  mct_u232_port_remove(struct usb_serial_port *remove);
43 static int  mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port);
44 static void mct_u232_close(struct usb_serial_port *port);
45 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on);
46 static void mct_u232_read_int_callback(struct urb *urb);
47 static void mct_u232_set_termios(struct tty_struct *tty,
48 			struct usb_serial_port *port, struct ktermios *old);
49 static void mct_u232_break_ctl(struct tty_struct *tty, int break_state);
50 static int  mct_u232_tiocmget(struct tty_struct *tty);
51 static int  mct_u232_tiocmset(struct tty_struct *tty,
52 			unsigned int set, unsigned int clear);
53 static void mct_u232_throttle(struct tty_struct *tty);
54 static void mct_u232_unthrottle(struct tty_struct *tty);
55 
56 
57 /*
58  * All of the device info needed for the MCT USB-RS232 converter.
59  */
60 static const struct usb_device_id id_table[] = {
61 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_PID) },
62 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_SITECOM_PID) },
63 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_DU_H3SP_PID) },
64 	{ USB_DEVICE(MCT_U232_BELKIN_F5U109_VID, MCT_U232_BELKIN_F5U109_PID) },
65 	{ }		/* Terminating entry */
66 };
67 MODULE_DEVICE_TABLE(usb, id_table);
68 
69 static struct usb_serial_driver mct_u232_device = {
70 	.driver = {
71 		.owner =	THIS_MODULE,
72 		.name =		"mct_u232",
73 	},
74 	.description =	     "MCT U232",
75 	.id_table =	     id_table,
76 	.num_ports =	     1,
77 	.open =		     mct_u232_open,
78 	.close =	     mct_u232_close,
79 	.dtr_rts =	     mct_u232_dtr_rts,
80 	.throttle =	     mct_u232_throttle,
81 	.unthrottle =	     mct_u232_unthrottle,
82 	.read_int_callback = mct_u232_read_int_callback,
83 	.set_termios =	     mct_u232_set_termios,
84 	.break_ctl =	     mct_u232_break_ctl,
85 	.tiocmget =	     mct_u232_tiocmget,
86 	.tiocmset =	     mct_u232_tiocmset,
87 	.tiocmiwait =        usb_serial_generic_tiocmiwait,
88 	.port_probe =        mct_u232_port_probe,
89 	.port_remove =       mct_u232_port_remove,
90 	.get_icount =        usb_serial_generic_get_icount,
91 };
92 
93 static struct usb_serial_driver * const serial_drivers[] = {
94 	&mct_u232_device, NULL
95 };
96 
97 struct mct_u232_private {
98 	struct urb *read_urb;
99 	spinlock_t lock;
100 	unsigned int	     control_state; /* Modem Line Setting (TIOCM) */
101 	unsigned char        last_lcr;      /* Line Control Register */
102 	unsigned char	     last_lsr;      /* Line Status Register */
103 	unsigned char	     last_msr;      /* Modem Status Register */
104 	unsigned int	     rx_flags;      /* Throttling flags */
105 };
106 
107 #define THROTTLED		0x01
108 
109 /*
110  * Handle vendor specific USB requests
111  */
112 
113 #define WDR_TIMEOUT 5000 /* default urb timeout */
114 
115 /*
116  * Later day 2.6.0-test kernels have new baud rates like B230400 which
117  * we do not know how to support. We ignore them for the moment.
118  */
119 static int mct_u232_calculate_baud_rate(struct usb_serial *serial,
120 					speed_t value, speed_t *result)
121 {
122 	*result = value;
123 
124 	if (le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_SITECOM_PID
125 		|| le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_BELKIN_F5U109_PID) {
126 		switch (value) {
127 		case 300:
128 			return 0x01;
129 		case 600:
130 			return 0x02; /* this one not tested */
131 		case 1200:
132 			return 0x03;
133 		case 2400:
134 			return 0x04;
135 		case 4800:
136 			return 0x06;
137 		case 9600:
138 			return 0x08;
139 		case 19200:
140 			return 0x09;
141 		case 38400:
142 			return 0x0a;
143 		case 57600:
144 			return 0x0b;
145 		case 115200:
146 			return 0x0c;
147 		default:
148 			*result = 9600;
149 			return 0x08;
150 		}
151 	} else {
152 		/* FIXME: Can we use any divider - should we do
153 		   divider = 115200/value;
154 		   real baud = 115200/divider */
155 		switch (value) {
156 		case 300: break;
157 		case 600: break;
158 		case 1200: break;
159 		case 2400: break;
160 		case 4800: break;
161 		case 9600: break;
162 		case 19200: break;
163 		case 38400: break;
164 		case 57600: break;
165 		case 115200: break;
166 		default:
167 			value = 9600;
168 			*result = 9600;
169 		}
170 		return 115200/value;
171 	}
172 }
173 
174 static int mct_u232_set_baud_rate(struct tty_struct *tty,
175 	struct usb_serial *serial, struct usb_serial_port *port, speed_t value)
176 {
177 	unsigned int divisor;
178 	int rc;
179 	unsigned char *buf;
180 	unsigned char cts_enable_byte = 0;
181 	speed_t speed;
182 
183 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
184 	if (buf == NULL)
185 		return -ENOMEM;
186 
187 	divisor = mct_u232_calculate_baud_rate(serial, value, &speed);
188 	put_unaligned_le32(divisor, buf);
189 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
190 				MCT_U232_SET_BAUD_RATE_REQUEST,
191 				MCT_U232_SET_REQUEST_TYPE,
192 				0, 0, buf, MCT_U232_SET_BAUD_RATE_SIZE,
193 				WDR_TIMEOUT);
194 	if (rc < 0)	/*FIXME: What value speed results */
195 		dev_err(&port->dev, "Set BAUD RATE %d failed (error = %d)\n",
196 			value, rc);
197 	else
198 		tty_encode_baud_rate(tty, speed, speed);
199 	dev_dbg(&port->dev, "set_baud_rate: value: 0x%x, divisor: 0x%x\n", value, divisor);
200 
201 	/* Mimic the MCT-supplied Windows driver (version 1.21P.0104), which
202 	   always sends two extra USB 'device request' messages after the
203 	   'baud rate change' message.  The actual functionality of the
204 	   request codes in these messages is not fully understood but these
205 	   particular codes are never seen in any operation besides a baud
206 	   rate change.  Both of these messages send a single byte of data.
207 	   In the first message, the value of this byte is always zero.
208 
209 	   The second message has been determined experimentally to control
210 	   whether data will be transmitted to a device which is not asserting
211 	   the 'CTS' signal.  If the second message's data byte is zero, data
212 	   will be transmitted even if 'CTS' is not asserted (i.e. no hardware
213 	   flow control).  if the second message's data byte is nonzero (a
214 	   value of 1 is used by this driver), data will not be transmitted to
215 	   a device which is not asserting 'CTS'.
216 	*/
217 
218 	buf[0] = 0;
219 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
220 				MCT_U232_SET_UNKNOWN1_REQUEST,
221 				MCT_U232_SET_REQUEST_TYPE,
222 				0, 0, buf, MCT_U232_SET_UNKNOWN1_SIZE,
223 				WDR_TIMEOUT);
224 	if (rc < 0)
225 		dev_err(&port->dev, "Sending USB device request code %d "
226 			"failed (error = %d)\n", MCT_U232_SET_UNKNOWN1_REQUEST,
227 			rc);
228 
229 	if (port && C_CRTSCTS(tty))
230 	   cts_enable_byte = 1;
231 
232 	dev_dbg(&port->dev, "set_baud_rate: send second control message, data = %02X\n",
233 		cts_enable_byte);
234 	buf[0] = cts_enable_byte;
235 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
236 			MCT_U232_SET_CTS_REQUEST,
237 			MCT_U232_SET_REQUEST_TYPE,
238 			0, 0, buf, MCT_U232_SET_CTS_SIZE,
239 			WDR_TIMEOUT);
240 	if (rc < 0)
241 		dev_err(&port->dev, "Sending USB device request code %d "
242 			"failed (error = %d)\n", MCT_U232_SET_CTS_REQUEST, rc);
243 
244 	kfree(buf);
245 	return rc;
246 } /* mct_u232_set_baud_rate */
247 
248 static int mct_u232_set_line_ctrl(struct usb_serial_port *port,
249 				  unsigned char lcr)
250 {
251 	int rc;
252 	unsigned char *buf;
253 
254 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
255 	if (buf == NULL)
256 		return -ENOMEM;
257 
258 	buf[0] = lcr;
259 	rc = usb_control_msg(port->serial->dev, usb_sndctrlpipe(port->serial->dev, 0),
260 			MCT_U232_SET_LINE_CTRL_REQUEST,
261 			MCT_U232_SET_REQUEST_TYPE,
262 			0, 0, buf, MCT_U232_SET_LINE_CTRL_SIZE,
263 			WDR_TIMEOUT);
264 	if (rc < 0)
265 		dev_err(&port->dev, "Set LINE CTRL 0x%x failed (error = %d)\n", lcr, rc);
266 	dev_dbg(&port->dev, "set_line_ctrl: 0x%x\n", lcr);
267 	kfree(buf);
268 	return rc;
269 } /* mct_u232_set_line_ctrl */
270 
271 static int mct_u232_set_modem_ctrl(struct usb_serial_port *port,
272 				   unsigned int control_state)
273 {
274 	int rc;
275 	unsigned char mcr;
276 	unsigned char *buf;
277 
278 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
279 	if (buf == NULL)
280 		return -ENOMEM;
281 
282 	mcr = MCT_U232_MCR_NONE;
283 	if (control_state & TIOCM_DTR)
284 		mcr |= MCT_U232_MCR_DTR;
285 	if (control_state & TIOCM_RTS)
286 		mcr |= MCT_U232_MCR_RTS;
287 
288 	buf[0] = mcr;
289 	rc = usb_control_msg(port->serial->dev, usb_sndctrlpipe(port->serial->dev, 0),
290 			MCT_U232_SET_MODEM_CTRL_REQUEST,
291 			MCT_U232_SET_REQUEST_TYPE,
292 			0, 0, buf, MCT_U232_SET_MODEM_CTRL_SIZE,
293 			WDR_TIMEOUT);
294 	kfree(buf);
295 
296 	dev_dbg(&port->dev, "set_modem_ctrl: state=0x%x ==> mcr=0x%x\n", control_state, mcr);
297 
298 	if (rc < 0) {
299 		dev_err(&port->dev, "Set MODEM CTRL 0x%x failed (error = %d)\n", mcr, rc);
300 		return rc;
301 	}
302 	return 0;
303 } /* mct_u232_set_modem_ctrl */
304 
305 static int mct_u232_get_modem_stat(struct usb_serial_port *port,
306 				   unsigned char *msr)
307 {
308 	int rc;
309 	unsigned char *buf;
310 
311 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
312 	if (buf == NULL) {
313 		*msr = 0;
314 		return -ENOMEM;
315 	}
316 	rc = usb_control_msg(port->serial->dev, usb_rcvctrlpipe(port->serial->dev, 0),
317 			MCT_U232_GET_MODEM_STAT_REQUEST,
318 			MCT_U232_GET_REQUEST_TYPE,
319 			0, 0, buf, MCT_U232_GET_MODEM_STAT_SIZE,
320 			WDR_TIMEOUT);
321 	if (rc < MCT_U232_GET_MODEM_STAT_SIZE) {
322 		dev_err(&port->dev, "Get MODEM STATus failed (error = %d)\n", rc);
323 
324 		if (rc >= 0)
325 			rc = -EIO;
326 
327 		*msr = 0;
328 	} else {
329 		*msr = buf[0];
330 	}
331 	dev_dbg(&port->dev, "get_modem_stat: 0x%x\n", *msr);
332 	kfree(buf);
333 	return rc;
334 } /* mct_u232_get_modem_stat */
335 
336 static void mct_u232_msr_to_icount(struct async_icount *icount,
337 						unsigned char msr)
338 {
339 	/* Translate Control Line states */
340 	if (msr & MCT_U232_MSR_DDSR)
341 		icount->dsr++;
342 	if (msr & MCT_U232_MSR_DCTS)
343 		icount->cts++;
344 	if (msr & MCT_U232_MSR_DRI)
345 		icount->rng++;
346 	if (msr & MCT_U232_MSR_DCD)
347 		icount->dcd++;
348 } /* mct_u232_msr_to_icount */
349 
350 static void mct_u232_msr_to_state(struct usb_serial_port *port,
351 				  unsigned int *control_state, unsigned char msr)
352 {
353 	/* Translate Control Line states */
354 	if (msr & MCT_U232_MSR_DSR)
355 		*control_state |=  TIOCM_DSR;
356 	else
357 		*control_state &= ~TIOCM_DSR;
358 	if (msr & MCT_U232_MSR_CTS)
359 		*control_state |=  TIOCM_CTS;
360 	else
361 		*control_state &= ~TIOCM_CTS;
362 	if (msr & MCT_U232_MSR_RI)
363 		*control_state |=  TIOCM_RI;
364 	else
365 		*control_state &= ~TIOCM_RI;
366 	if (msr & MCT_U232_MSR_CD)
367 		*control_state |=  TIOCM_CD;
368 	else
369 		*control_state &= ~TIOCM_CD;
370 	dev_dbg(&port->dev, "msr_to_state: msr=0x%x ==> state=0x%x\n", msr, *control_state);
371 } /* mct_u232_msr_to_state */
372 
373 /*
374  * Driver's tty interface functions
375  */
376 
377 static int mct_u232_port_probe(struct usb_serial_port *port)
378 {
379 	struct usb_serial *serial = port->serial;
380 	struct mct_u232_private *priv;
381 
382 	/* check first to simplify error handling */
383 	if (!serial->port[1] || !serial->port[1]->interrupt_in_urb) {
384 		dev_err(&port->dev, "expected endpoint missing\n");
385 		return -ENODEV;
386 	}
387 
388 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
389 	if (!priv)
390 		return -ENOMEM;
391 
392 	/* Use second interrupt-in endpoint for reading. */
393 	priv->read_urb = serial->port[1]->interrupt_in_urb;
394 	priv->read_urb->context = port;
395 
396 	spin_lock_init(&priv->lock);
397 
398 	usb_set_serial_port_data(port, priv);
399 
400 	return 0;
401 }
402 
403 static int mct_u232_port_remove(struct usb_serial_port *port)
404 {
405 	struct mct_u232_private *priv;
406 
407 	priv = usb_get_serial_port_data(port);
408 	kfree(priv);
409 
410 	return 0;
411 }
412 
413 static int  mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port)
414 {
415 	struct usb_serial *serial = port->serial;
416 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
417 	int retval = 0;
418 	unsigned int control_state;
419 	unsigned long flags;
420 	unsigned char last_lcr;
421 	unsigned char last_msr;
422 
423 	/* Compensate for a hardware bug: although the Sitecom U232-P25
424 	 * device reports a maximum output packet size of 32 bytes,
425 	 * it seems to be able to accept only 16 bytes (and that's what
426 	 * SniffUSB says too...)
427 	 */
428 	if (le16_to_cpu(serial->dev->descriptor.idProduct)
429 						== MCT_U232_SITECOM_PID)
430 		port->bulk_out_size = 16;
431 
432 	/* Do a defined restart: the normal serial device seems to
433 	 * always turn on DTR and RTS here, so do the same. I'm not
434 	 * sure if this is really necessary. But it should not harm
435 	 * either.
436 	 */
437 	spin_lock_irqsave(&priv->lock, flags);
438 	if (tty && C_BAUD(tty))
439 		priv->control_state = TIOCM_DTR | TIOCM_RTS;
440 	else
441 		priv->control_state = 0;
442 
443 	priv->last_lcr = (MCT_U232_DATA_BITS_8 |
444 			  MCT_U232_PARITY_NONE |
445 			  MCT_U232_STOP_BITS_1);
446 	control_state = priv->control_state;
447 	last_lcr = priv->last_lcr;
448 	spin_unlock_irqrestore(&priv->lock, flags);
449 	mct_u232_set_modem_ctrl(port, control_state);
450 	mct_u232_set_line_ctrl(port, last_lcr);
451 
452 	/* Read modem status and update control state */
453 	mct_u232_get_modem_stat(port, &last_msr);
454 	spin_lock_irqsave(&priv->lock, flags);
455 	priv->last_msr = last_msr;
456 	mct_u232_msr_to_state(port, &priv->control_state, priv->last_msr);
457 	spin_unlock_irqrestore(&priv->lock, flags);
458 
459 	retval = usb_submit_urb(priv->read_urb, GFP_KERNEL);
460 	if (retval) {
461 		dev_err(&port->dev,
462 			"usb_submit_urb(read) failed pipe 0x%x err %d\n",
463 			port->read_urb->pipe, retval);
464 		goto error;
465 	}
466 
467 	retval = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
468 	if (retval) {
469 		usb_kill_urb(priv->read_urb);
470 		dev_err(&port->dev,
471 			"usb_submit_urb(read int) failed pipe 0x%x err %d",
472 			port->interrupt_in_urb->pipe, retval);
473 		goto error;
474 	}
475 	return 0;
476 
477 error:
478 	return retval;
479 } /* mct_u232_open */
480 
481 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on)
482 {
483 	unsigned int control_state;
484 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
485 
486 	spin_lock_irq(&priv->lock);
487 	if (on)
488 		priv->control_state |= TIOCM_DTR | TIOCM_RTS;
489 	else
490 		priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
491 	control_state = priv->control_state;
492 	spin_unlock_irq(&priv->lock);
493 
494 	mct_u232_set_modem_ctrl(port, control_state);
495 }
496 
497 static void mct_u232_close(struct usb_serial_port *port)
498 {
499 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
500 
501 	usb_kill_urb(priv->read_urb);
502 	usb_kill_urb(port->interrupt_in_urb);
503 
504 	usb_serial_generic_close(port);
505 } /* mct_u232_close */
506 
507 
508 static void mct_u232_read_int_callback(struct urb *urb)
509 {
510 	struct usb_serial_port *port = urb->context;
511 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
512 	unsigned char *data = urb->transfer_buffer;
513 	int retval;
514 	int status = urb->status;
515 	unsigned long flags;
516 
517 	switch (status) {
518 	case 0:
519 		/* success */
520 		break;
521 	case -ECONNRESET:
522 	case -ENOENT:
523 	case -ESHUTDOWN:
524 		/* this urb is terminated, clean up */
525 		dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
526 			__func__, status);
527 		return;
528 	default:
529 		dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
530 			__func__, status);
531 		goto exit;
532 	}
533 
534 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
535 
536 	/*
537 	 * Work-a-round: handle the 'usual' bulk-in pipe here
538 	 */
539 	if (urb->transfer_buffer_length > 2) {
540 		if (urb->actual_length) {
541 			tty_insert_flip_string(&port->port, data,
542 					urb->actual_length);
543 			tty_flip_buffer_push(&port->port);
544 		}
545 		goto exit;
546 	}
547 
548 	/*
549 	 * The interrupt-in pipe signals exceptional conditions (modem line
550 	 * signal changes and errors). data[0] holds MSR, data[1] holds LSR.
551 	 */
552 	spin_lock_irqsave(&priv->lock, flags);
553 	priv->last_msr = data[MCT_U232_MSR_INDEX];
554 
555 	/* Record Control Line states */
556 	mct_u232_msr_to_state(port, &priv->control_state, priv->last_msr);
557 
558 	mct_u232_msr_to_icount(&port->icount, priv->last_msr);
559 
560 #if 0
561 	/* Not yet handled. See belkin_sa.c for further information */
562 	/* Now to report any errors */
563 	priv->last_lsr = data[MCT_U232_LSR_INDEX];
564 	/*
565 	 * fill in the flip buffer here, but I do not know the relation
566 	 * to the current/next receive buffer or characters.  I need
567 	 * to look in to this before committing any code.
568 	 */
569 	if (priv->last_lsr & MCT_U232_LSR_ERR) {
570 		tty = tty_port_tty_get(&port->port);
571 		/* Overrun Error */
572 		if (priv->last_lsr & MCT_U232_LSR_OE) {
573 		}
574 		/* Parity Error */
575 		if (priv->last_lsr & MCT_U232_LSR_PE) {
576 		}
577 		/* Framing Error */
578 		if (priv->last_lsr & MCT_U232_LSR_FE) {
579 		}
580 		/* Break Indicator */
581 		if (priv->last_lsr & MCT_U232_LSR_BI) {
582 		}
583 		tty_kref_put(tty);
584 	}
585 #endif
586 	wake_up_interruptible(&port->port.delta_msr_wait);
587 	spin_unlock_irqrestore(&priv->lock, flags);
588 exit:
589 	retval = usb_submit_urb(urb, GFP_ATOMIC);
590 	if (retval)
591 		dev_err(&port->dev,
592 			"%s - usb_submit_urb failed with result %d\n",
593 			__func__, retval);
594 } /* mct_u232_read_int_callback */
595 
596 static void mct_u232_set_termios(struct tty_struct *tty,
597 				 struct usb_serial_port *port,
598 				 struct ktermios *old_termios)
599 {
600 	struct usb_serial *serial = port->serial;
601 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
602 	struct ktermios *termios = &tty->termios;
603 	unsigned int cflag = termios->c_cflag;
604 	unsigned int old_cflag = old_termios->c_cflag;
605 	unsigned long flags;
606 	unsigned int control_state;
607 	unsigned char last_lcr;
608 
609 	/* get a local copy of the current port settings */
610 	spin_lock_irqsave(&priv->lock, flags);
611 	control_state = priv->control_state;
612 	spin_unlock_irqrestore(&priv->lock, flags);
613 	last_lcr = 0;
614 
615 	/*
616 	 * Update baud rate.
617 	 * Do not attempt to cache old rates and skip settings,
618 	 * disconnects screw such tricks up completely.
619 	 * Premature optimization is the root of all evil.
620 	 */
621 
622 	/* reassert DTR and RTS on transition from B0 */
623 	if ((old_cflag & CBAUD) == B0) {
624 		dev_dbg(&port->dev, "%s: baud was B0\n", __func__);
625 		control_state |= TIOCM_DTR | TIOCM_RTS;
626 		mct_u232_set_modem_ctrl(port, control_state);
627 	}
628 
629 	mct_u232_set_baud_rate(tty, serial, port, tty_get_baud_rate(tty));
630 
631 	if ((cflag & CBAUD) == B0) {
632 		dev_dbg(&port->dev, "%s: baud is B0\n", __func__);
633 		/* Drop RTS and DTR */
634 		control_state &= ~(TIOCM_DTR | TIOCM_RTS);
635 		mct_u232_set_modem_ctrl(port, control_state);
636 	}
637 
638 	/*
639 	 * Update line control register (LCR)
640 	 */
641 
642 	/* set the parity */
643 	if (cflag & PARENB)
644 		last_lcr |= (cflag & PARODD) ?
645 			MCT_U232_PARITY_ODD : MCT_U232_PARITY_EVEN;
646 	else
647 		last_lcr |= MCT_U232_PARITY_NONE;
648 
649 	/* set the number of data bits */
650 	switch (cflag & CSIZE) {
651 	case CS5:
652 		last_lcr |= MCT_U232_DATA_BITS_5; break;
653 	case CS6:
654 		last_lcr |= MCT_U232_DATA_BITS_6; break;
655 	case CS7:
656 		last_lcr |= MCT_U232_DATA_BITS_7; break;
657 	case CS8:
658 		last_lcr |= MCT_U232_DATA_BITS_8; break;
659 	default:
660 		dev_err(&port->dev,
661 			"CSIZE was not CS5-CS8, using default of 8\n");
662 		last_lcr |= MCT_U232_DATA_BITS_8;
663 		break;
664 	}
665 
666 	termios->c_cflag &= ~CMSPAR;
667 
668 	/* set the number of stop bits */
669 	last_lcr |= (cflag & CSTOPB) ?
670 		MCT_U232_STOP_BITS_2 : MCT_U232_STOP_BITS_1;
671 
672 	mct_u232_set_line_ctrl(port, last_lcr);
673 
674 	/* save off the modified port settings */
675 	spin_lock_irqsave(&priv->lock, flags);
676 	priv->control_state = control_state;
677 	priv->last_lcr = last_lcr;
678 	spin_unlock_irqrestore(&priv->lock, flags);
679 } /* mct_u232_set_termios */
680 
681 static void mct_u232_break_ctl(struct tty_struct *tty, int break_state)
682 {
683 	struct usb_serial_port *port = tty->driver_data;
684 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
685 	unsigned char lcr;
686 	unsigned long flags;
687 
688 	spin_lock_irqsave(&priv->lock, flags);
689 	lcr = priv->last_lcr;
690 
691 	if (break_state)
692 		lcr |= MCT_U232_SET_BREAK;
693 	spin_unlock_irqrestore(&priv->lock, flags);
694 
695 	mct_u232_set_line_ctrl(port, lcr);
696 } /* mct_u232_break_ctl */
697 
698 
699 static int mct_u232_tiocmget(struct tty_struct *tty)
700 {
701 	struct usb_serial_port *port = tty->driver_data;
702 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
703 	unsigned int control_state;
704 	unsigned long flags;
705 
706 	spin_lock_irqsave(&priv->lock, flags);
707 	control_state = priv->control_state;
708 	spin_unlock_irqrestore(&priv->lock, flags);
709 
710 	return control_state;
711 }
712 
713 static int mct_u232_tiocmset(struct tty_struct *tty,
714 			      unsigned int set, unsigned int clear)
715 {
716 	struct usb_serial_port *port = tty->driver_data;
717 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
718 	unsigned int control_state;
719 	unsigned long flags;
720 
721 	spin_lock_irqsave(&priv->lock, flags);
722 	control_state = priv->control_state;
723 
724 	if (set & TIOCM_RTS)
725 		control_state |= TIOCM_RTS;
726 	if (set & TIOCM_DTR)
727 		control_state |= TIOCM_DTR;
728 	if (clear & TIOCM_RTS)
729 		control_state &= ~TIOCM_RTS;
730 	if (clear & TIOCM_DTR)
731 		control_state &= ~TIOCM_DTR;
732 
733 	priv->control_state = control_state;
734 	spin_unlock_irqrestore(&priv->lock, flags);
735 	return mct_u232_set_modem_ctrl(port, control_state);
736 }
737 
738 static void mct_u232_throttle(struct tty_struct *tty)
739 {
740 	struct usb_serial_port *port = tty->driver_data;
741 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
742 	unsigned int control_state;
743 
744 	spin_lock_irq(&priv->lock);
745 	priv->rx_flags |= THROTTLED;
746 	if (C_CRTSCTS(tty)) {
747 		priv->control_state &= ~TIOCM_RTS;
748 		control_state = priv->control_state;
749 		spin_unlock_irq(&priv->lock);
750 		mct_u232_set_modem_ctrl(port, control_state);
751 	} else {
752 		spin_unlock_irq(&priv->lock);
753 	}
754 }
755 
756 static void mct_u232_unthrottle(struct tty_struct *tty)
757 {
758 	struct usb_serial_port *port = tty->driver_data;
759 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
760 	unsigned int control_state;
761 
762 	spin_lock_irq(&priv->lock);
763 	if ((priv->rx_flags & THROTTLED) && C_CRTSCTS(tty)) {
764 		priv->rx_flags &= ~THROTTLED;
765 		priv->control_state |= TIOCM_RTS;
766 		control_state = priv->control_state;
767 		spin_unlock_irq(&priv->lock);
768 		mct_u232_set_modem_ctrl(port, control_state);
769 	} else {
770 		spin_unlock_irq(&priv->lock);
771 	}
772 }
773 
774 module_usb_serial_driver(serial_drivers, id_table);
775 
776 MODULE_AUTHOR(DRIVER_AUTHOR);
777 MODULE_DESCRIPTION(DRIVER_DESC);
778 MODULE_LICENSE("GPL");
779