xref: /linux/drivers/usb/serial/mct_u232.c (revision 93d90ad708b8da6efc0e487b66111aa9db7f70c7)
1 /*
2  * MCT (Magic Control Technology Corp.) USB RS232 Converter Driver
3  *
4  *   Copyright (C) 2000 Wolfgang Grandegger (wolfgang@ces.ch)
5  *
6  *   This program is free software; you can redistribute it and/or modify
7  *   it under the terms of the GNU General Public License as published by
8  *   the Free Software Foundation; either version 2 of the License, or
9  *   (at your option) any later version.
10  *
11  * This program is largely derived from the Belkin USB Serial Adapter Driver
12  * (see belkin_sa.[ch]). All of the information about the device was acquired
13  * by using SniffUSB on Windows98. For technical details see mct_u232.h.
14  *
15  * William G. Greathouse and Greg Kroah-Hartman provided great help on how to
16  * do the reverse engineering and how to write a USB serial device driver.
17  *
18  * TO BE DONE, TO BE CHECKED:
19  *   DTR/RTS signal handling may be incomplete or incorrect. I have mainly
20  *   implemented what I have seen with SniffUSB or found in belkin_sa.c.
21  *   For further TODOs check also belkin_sa.c.
22  */
23 
24 #include <linux/kernel.h>
25 #include <linux/errno.h>
26 #include <linux/slab.h>
27 #include <linux/tty.h>
28 #include <linux/tty_driver.h>
29 #include <linux/tty_flip.h>
30 #include <linux/module.h>
31 #include <linux/spinlock.h>
32 #include <linux/uaccess.h>
33 #include <asm/unaligned.h>
34 #include <linux/usb.h>
35 #include <linux/usb/serial.h>
36 #include <linux/serial.h>
37 #include "mct_u232.h"
38 
39 #define DRIVER_AUTHOR "Wolfgang Grandegger <wolfgang@ces.ch>"
40 #define DRIVER_DESC "Magic Control Technology USB-RS232 converter driver"
41 
42 /*
43  * Function prototypes
44  */
45 static int  mct_u232_port_probe(struct usb_serial_port *port);
46 static int  mct_u232_port_remove(struct usb_serial_port *remove);
47 static int  mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port);
48 static void mct_u232_close(struct usb_serial_port *port);
49 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on);
50 static void mct_u232_read_int_callback(struct urb *urb);
51 static void mct_u232_set_termios(struct tty_struct *tty,
52 			struct usb_serial_port *port, struct ktermios *old);
53 static void mct_u232_break_ctl(struct tty_struct *tty, int break_state);
54 static int  mct_u232_tiocmget(struct tty_struct *tty);
55 static int  mct_u232_tiocmset(struct tty_struct *tty,
56 			unsigned int set, unsigned int clear);
57 static void mct_u232_throttle(struct tty_struct *tty);
58 static void mct_u232_unthrottle(struct tty_struct *tty);
59 
60 
61 /*
62  * All of the device info needed for the MCT USB-RS232 converter.
63  */
64 static const struct usb_device_id id_table[] = {
65 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_PID) },
66 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_SITECOM_PID) },
67 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_DU_H3SP_PID) },
68 	{ USB_DEVICE(MCT_U232_BELKIN_F5U109_VID, MCT_U232_BELKIN_F5U109_PID) },
69 	{ }		/* Terminating entry */
70 };
71 MODULE_DEVICE_TABLE(usb, id_table);
72 
73 static struct usb_serial_driver mct_u232_device = {
74 	.driver = {
75 		.owner =	THIS_MODULE,
76 		.name =		"mct_u232",
77 	},
78 	.description =	     "MCT U232",
79 	.id_table =	     id_table,
80 	.num_ports =	     1,
81 	.open =		     mct_u232_open,
82 	.close =	     mct_u232_close,
83 	.dtr_rts =	     mct_u232_dtr_rts,
84 	.throttle =	     mct_u232_throttle,
85 	.unthrottle =	     mct_u232_unthrottle,
86 	.read_int_callback = mct_u232_read_int_callback,
87 	.set_termios =	     mct_u232_set_termios,
88 	.break_ctl =	     mct_u232_break_ctl,
89 	.tiocmget =	     mct_u232_tiocmget,
90 	.tiocmset =	     mct_u232_tiocmset,
91 	.tiocmiwait =        usb_serial_generic_tiocmiwait,
92 	.port_probe =        mct_u232_port_probe,
93 	.port_remove =       mct_u232_port_remove,
94 	.get_icount =        usb_serial_generic_get_icount,
95 };
96 
97 static struct usb_serial_driver * const serial_drivers[] = {
98 	&mct_u232_device, NULL
99 };
100 
101 struct mct_u232_private {
102 	struct urb *read_urb;
103 	spinlock_t lock;
104 	unsigned int	     control_state; /* Modem Line Setting (TIOCM) */
105 	unsigned char        last_lcr;      /* Line Control Register */
106 	unsigned char	     last_lsr;      /* Line Status Register */
107 	unsigned char	     last_msr;      /* Modem Status Register */
108 	unsigned int	     rx_flags;      /* Throttling flags */
109 };
110 
111 #define THROTTLED		0x01
112 
113 /*
114  * Handle vendor specific USB requests
115  */
116 
117 #define WDR_TIMEOUT 5000 /* default urb timeout */
118 
119 /*
120  * Later day 2.6.0-test kernels have new baud rates like B230400 which
121  * we do not know how to support. We ignore them for the moment.
122  */
123 static int mct_u232_calculate_baud_rate(struct usb_serial *serial,
124 					speed_t value, speed_t *result)
125 {
126 	*result = value;
127 
128 	if (le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_SITECOM_PID
129 		|| le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_BELKIN_F5U109_PID) {
130 		switch (value) {
131 		case 300:
132 			return 0x01;
133 		case 600:
134 			return 0x02; /* this one not tested */
135 		case 1200:
136 			return 0x03;
137 		case 2400:
138 			return 0x04;
139 		case 4800:
140 			return 0x06;
141 		case 9600:
142 			return 0x08;
143 		case 19200:
144 			return 0x09;
145 		case 38400:
146 			return 0x0a;
147 		case 57600:
148 			return 0x0b;
149 		case 115200:
150 			return 0x0c;
151 		default:
152 			*result = 9600;
153 			return 0x08;
154 		}
155 	} else {
156 		/* FIXME: Can we use any divider - should we do
157 		   divider = 115200/value;
158 		   real baud = 115200/divider */
159 		switch (value) {
160 		case 300: break;
161 		case 600: break;
162 		case 1200: break;
163 		case 2400: break;
164 		case 4800: break;
165 		case 9600: break;
166 		case 19200: break;
167 		case 38400: break;
168 		case 57600: break;
169 		case 115200: break;
170 		default:
171 			value = 9600;
172 			*result = 9600;
173 		}
174 		return 115200/value;
175 	}
176 }
177 
178 static int mct_u232_set_baud_rate(struct tty_struct *tty,
179 	struct usb_serial *serial, struct usb_serial_port *port, speed_t value)
180 {
181 	unsigned int divisor;
182 	int rc;
183 	unsigned char *buf;
184 	unsigned char cts_enable_byte = 0;
185 	speed_t speed;
186 
187 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
188 	if (buf == NULL)
189 		return -ENOMEM;
190 
191 	divisor = mct_u232_calculate_baud_rate(serial, value, &speed);
192 	put_unaligned_le32(cpu_to_le32(divisor), buf);
193 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
194 				MCT_U232_SET_BAUD_RATE_REQUEST,
195 				MCT_U232_SET_REQUEST_TYPE,
196 				0, 0, buf, MCT_U232_SET_BAUD_RATE_SIZE,
197 				WDR_TIMEOUT);
198 	if (rc < 0)	/*FIXME: What value speed results */
199 		dev_err(&port->dev, "Set BAUD RATE %d failed (error = %d)\n",
200 			value, rc);
201 	else
202 		tty_encode_baud_rate(tty, speed, speed);
203 	dev_dbg(&port->dev, "set_baud_rate: value: 0x%x, divisor: 0x%x\n", value, divisor);
204 
205 	/* Mimic the MCT-supplied Windows driver (version 1.21P.0104), which
206 	   always sends two extra USB 'device request' messages after the
207 	   'baud rate change' message.  The actual functionality of the
208 	   request codes in these messages is not fully understood but these
209 	   particular codes are never seen in any operation besides a baud
210 	   rate change.  Both of these messages send a single byte of data.
211 	   In the first message, the value of this byte is always zero.
212 
213 	   The second message has been determined experimentally to control
214 	   whether data will be transmitted to a device which is not asserting
215 	   the 'CTS' signal.  If the second message's data byte is zero, data
216 	   will be transmitted even if 'CTS' is not asserted (i.e. no hardware
217 	   flow control).  if the second message's data byte is nonzero (a
218 	   value of 1 is used by this driver), data will not be transmitted to
219 	   a device which is not asserting 'CTS'.
220 	*/
221 
222 	buf[0] = 0;
223 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
224 				MCT_U232_SET_UNKNOWN1_REQUEST,
225 				MCT_U232_SET_REQUEST_TYPE,
226 				0, 0, buf, MCT_U232_SET_UNKNOWN1_SIZE,
227 				WDR_TIMEOUT);
228 	if (rc < 0)
229 		dev_err(&port->dev, "Sending USB device request code %d "
230 			"failed (error = %d)\n", MCT_U232_SET_UNKNOWN1_REQUEST,
231 			rc);
232 
233 	if (port && C_CRTSCTS(tty))
234 	   cts_enable_byte = 1;
235 
236 	dev_dbg(&port->dev, "set_baud_rate: send second control message, data = %02X\n",
237 		cts_enable_byte);
238 	buf[0] = cts_enable_byte;
239 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
240 			MCT_U232_SET_CTS_REQUEST,
241 			MCT_U232_SET_REQUEST_TYPE,
242 			0, 0, buf, MCT_U232_SET_CTS_SIZE,
243 			WDR_TIMEOUT);
244 	if (rc < 0)
245 		dev_err(&port->dev, "Sending USB device request code %d "
246 			"failed (error = %d)\n", MCT_U232_SET_CTS_REQUEST, rc);
247 
248 	kfree(buf);
249 	return rc;
250 } /* mct_u232_set_baud_rate */
251 
252 static int mct_u232_set_line_ctrl(struct usb_serial_port *port,
253 				  unsigned char lcr)
254 {
255 	int rc;
256 	unsigned char *buf;
257 
258 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
259 	if (buf == NULL)
260 		return -ENOMEM;
261 
262 	buf[0] = lcr;
263 	rc = usb_control_msg(port->serial->dev, usb_sndctrlpipe(port->serial->dev, 0),
264 			MCT_U232_SET_LINE_CTRL_REQUEST,
265 			MCT_U232_SET_REQUEST_TYPE,
266 			0, 0, buf, MCT_U232_SET_LINE_CTRL_SIZE,
267 			WDR_TIMEOUT);
268 	if (rc < 0)
269 		dev_err(&port->dev, "Set LINE CTRL 0x%x failed (error = %d)\n", lcr, rc);
270 	dev_dbg(&port->dev, "set_line_ctrl: 0x%x\n", lcr);
271 	kfree(buf);
272 	return rc;
273 } /* mct_u232_set_line_ctrl */
274 
275 static int mct_u232_set_modem_ctrl(struct usb_serial_port *port,
276 				   unsigned int control_state)
277 {
278 	int rc;
279 	unsigned char mcr;
280 	unsigned char *buf;
281 
282 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
283 	if (buf == NULL)
284 		return -ENOMEM;
285 
286 	mcr = MCT_U232_MCR_NONE;
287 	if (control_state & TIOCM_DTR)
288 		mcr |= MCT_U232_MCR_DTR;
289 	if (control_state & TIOCM_RTS)
290 		mcr |= MCT_U232_MCR_RTS;
291 
292 	buf[0] = mcr;
293 	rc = usb_control_msg(port->serial->dev, usb_sndctrlpipe(port->serial->dev, 0),
294 			MCT_U232_SET_MODEM_CTRL_REQUEST,
295 			MCT_U232_SET_REQUEST_TYPE,
296 			0, 0, buf, MCT_U232_SET_MODEM_CTRL_SIZE,
297 			WDR_TIMEOUT);
298 	kfree(buf);
299 
300 	dev_dbg(&port->dev, "set_modem_ctrl: state=0x%x ==> mcr=0x%x\n", control_state, mcr);
301 
302 	if (rc < 0) {
303 		dev_err(&port->dev, "Set MODEM CTRL 0x%x failed (error = %d)\n", mcr, rc);
304 		return rc;
305 	}
306 	return 0;
307 } /* mct_u232_set_modem_ctrl */
308 
309 static int mct_u232_get_modem_stat(struct usb_serial_port *port,
310 				   unsigned char *msr)
311 {
312 	int rc;
313 	unsigned char *buf;
314 
315 	buf = kmalloc(MCT_U232_MAX_SIZE, GFP_KERNEL);
316 	if (buf == NULL) {
317 		*msr = 0;
318 		return -ENOMEM;
319 	}
320 	rc = usb_control_msg(port->serial->dev, usb_rcvctrlpipe(port->serial->dev, 0),
321 			MCT_U232_GET_MODEM_STAT_REQUEST,
322 			MCT_U232_GET_REQUEST_TYPE,
323 			0, 0, buf, MCT_U232_GET_MODEM_STAT_SIZE,
324 			WDR_TIMEOUT);
325 	if (rc < 0) {
326 		dev_err(&port->dev, "Get MODEM STATus failed (error = %d)\n", rc);
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 mct_u232_private *priv;
380 
381 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
382 	if (!priv)
383 		return -ENOMEM;
384 
385 	/* Use second interrupt-in endpoint for reading. */
386 	priv->read_urb = port->serial->port[1]->interrupt_in_urb;
387 	priv->read_urb->context = port;
388 
389 	spin_lock_init(&priv->lock);
390 
391 	usb_set_serial_port_data(port, priv);
392 
393 	return 0;
394 }
395 
396 static int mct_u232_port_remove(struct usb_serial_port *port)
397 {
398 	struct mct_u232_private *priv;
399 
400 	priv = usb_get_serial_port_data(port);
401 	kfree(priv);
402 
403 	return 0;
404 }
405 
406 static int  mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port)
407 {
408 	struct usb_serial *serial = port->serial;
409 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
410 	int retval = 0;
411 	unsigned int control_state;
412 	unsigned long flags;
413 	unsigned char last_lcr;
414 	unsigned char last_msr;
415 
416 	/* Compensate for a hardware bug: although the Sitecom U232-P25
417 	 * device reports a maximum output packet size of 32 bytes,
418 	 * it seems to be able to accept only 16 bytes (and that's what
419 	 * SniffUSB says too...)
420 	 */
421 	if (le16_to_cpu(serial->dev->descriptor.idProduct)
422 						== MCT_U232_SITECOM_PID)
423 		port->bulk_out_size = 16;
424 
425 	/* Do a defined restart: the normal serial device seems to
426 	 * always turn on DTR and RTS here, so do the same. I'm not
427 	 * sure if this is really necessary. But it should not harm
428 	 * either.
429 	 */
430 	spin_lock_irqsave(&priv->lock, flags);
431 	if (tty && (tty->termios.c_cflag & CBAUD))
432 		priv->control_state = TIOCM_DTR | TIOCM_RTS;
433 	else
434 		priv->control_state = 0;
435 
436 	priv->last_lcr = (MCT_U232_DATA_BITS_8 |
437 			  MCT_U232_PARITY_NONE |
438 			  MCT_U232_STOP_BITS_1);
439 	control_state = priv->control_state;
440 	last_lcr = priv->last_lcr;
441 	spin_unlock_irqrestore(&priv->lock, flags);
442 	mct_u232_set_modem_ctrl(port, control_state);
443 	mct_u232_set_line_ctrl(port, last_lcr);
444 
445 	/* Read modem status and update control state */
446 	mct_u232_get_modem_stat(port, &last_msr);
447 	spin_lock_irqsave(&priv->lock, flags);
448 	priv->last_msr = last_msr;
449 	mct_u232_msr_to_state(port, &priv->control_state, priv->last_msr);
450 	spin_unlock_irqrestore(&priv->lock, flags);
451 
452 	retval = usb_submit_urb(priv->read_urb, GFP_KERNEL);
453 	if (retval) {
454 		dev_err(&port->dev,
455 			"usb_submit_urb(read) failed pipe 0x%x err %d\n",
456 			port->read_urb->pipe, retval);
457 		goto error;
458 	}
459 
460 	retval = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
461 	if (retval) {
462 		usb_kill_urb(priv->read_urb);
463 		dev_err(&port->dev,
464 			"usb_submit_urb(read int) failed pipe 0x%x err %d",
465 			port->interrupt_in_urb->pipe, retval);
466 		goto error;
467 	}
468 	return 0;
469 
470 error:
471 	return retval;
472 } /* mct_u232_open */
473 
474 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on)
475 {
476 	unsigned int control_state;
477 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
478 
479 	spin_lock_irq(&priv->lock);
480 	if (on)
481 		priv->control_state |= TIOCM_DTR | TIOCM_RTS;
482 	else
483 		priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
484 	control_state = priv->control_state;
485 	spin_unlock_irq(&priv->lock);
486 
487 	mct_u232_set_modem_ctrl(port, control_state);
488 }
489 
490 static void mct_u232_close(struct usb_serial_port *port)
491 {
492 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
493 
494 	usb_kill_urb(priv->read_urb);
495 	usb_kill_urb(port->interrupt_in_urb);
496 
497 	usb_serial_generic_close(port);
498 } /* mct_u232_close */
499 
500 
501 static void mct_u232_read_int_callback(struct urb *urb)
502 {
503 	struct usb_serial_port *port = urb->context;
504 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
505 	unsigned char *data = urb->transfer_buffer;
506 	int retval;
507 	int status = urb->status;
508 	unsigned long flags;
509 
510 	switch (status) {
511 	case 0:
512 		/* success */
513 		break;
514 	case -ECONNRESET:
515 	case -ENOENT:
516 	case -ESHUTDOWN:
517 		/* this urb is terminated, clean up */
518 		dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
519 			__func__, status);
520 		return;
521 	default:
522 		dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
523 			__func__, status);
524 		goto exit;
525 	}
526 
527 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
528 
529 	/*
530 	 * Work-a-round: handle the 'usual' bulk-in pipe here
531 	 */
532 	if (urb->transfer_buffer_length > 2) {
533 		if (urb->actual_length) {
534 			tty_insert_flip_string(&port->port, data,
535 					urb->actual_length);
536 			tty_flip_buffer_push(&port->port);
537 		}
538 		goto exit;
539 	}
540 
541 	/*
542 	 * The interrupt-in pipe signals exceptional conditions (modem line
543 	 * signal changes and errors). data[0] holds MSR, data[1] holds LSR.
544 	 */
545 	spin_lock_irqsave(&priv->lock, flags);
546 	priv->last_msr = data[MCT_U232_MSR_INDEX];
547 
548 	/* Record Control Line states */
549 	mct_u232_msr_to_state(port, &priv->control_state, priv->last_msr);
550 
551 	mct_u232_msr_to_icount(&port->icount, priv->last_msr);
552 
553 #if 0
554 	/* Not yet handled. See belkin_sa.c for further information */
555 	/* Now to report any errors */
556 	priv->last_lsr = data[MCT_U232_LSR_INDEX];
557 	/*
558 	 * fill in the flip buffer here, but I do not know the relation
559 	 * to the current/next receive buffer or characters.  I need
560 	 * to look in to this before committing any code.
561 	 */
562 	if (priv->last_lsr & MCT_U232_LSR_ERR) {
563 		tty = tty_port_tty_get(&port->port);
564 		/* Overrun Error */
565 		if (priv->last_lsr & MCT_U232_LSR_OE) {
566 		}
567 		/* Parity Error */
568 		if (priv->last_lsr & MCT_U232_LSR_PE) {
569 		}
570 		/* Framing Error */
571 		if (priv->last_lsr & MCT_U232_LSR_FE) {
572 		}
573 		/* Break Indicator */
574 		if (priv->last_lsr & MCT_U232_LSR_BI) {
575 		}
576 		tty_kref_put(tty);
577 	}
578 #endif
579 	wake_up_interruptible(&port->port.delta_msr_wait);
580 	spin_unlock_irqrestore(&priv->lock, flags);
581 exit:
582 	retval = usb_submit_urb(urb, GFP_ATOMIC);
583 	if (retval)
584 		dev_err(&port->dev,
585 			"%s - usb_submit_urb failed with result %d\n",
586 			__func__, retval);
587 } /* mct_u232_read_int_callback */
588 
589 static void mct_u232_set_termios(struct tty_struct *tty,
590 				 struct usb_serial_port *port,
591 				 struct ktermios *old_termios)
592 {
593 	struct usb_serial *serial = port->serial;
594 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
595 	struct ktermios *termios = &tty->termios;
596 	unsigned int cflag = termios->c_cflag;
597 	unsigned int old_cflag = old_termios->c_cflag;
598 	unsigned long flags;
599 	unsigned int control_state;
600 	unsigned char last_lcr;
601 
602 	/* get a local copy of the current port settings */
603 	spin_lock_irqsave(&priv->lock, flags);
604 	control_state = priv->control_state;
605 	spin_unlock_irqrestore(&priv->lock, flags);
606 	last_lcr = 0;
607 
608 	/*
609 	 * Update baud rate.
610 	 * Do not attempt to cache old rates and skip settings,
611 	 * disconnects screw such tricks up completely.
612 	 * Premature optimization is the root of all evil.
613 	 */
614 
615 	/* reassert DTR and RTS on transition from B0 */
616 	if ((old_cflag & CBAUD) == B0) {
617 		dev_dbg(&port->dev, "%s: baud was B0\n", __func__);
618 		control_state |= TIOCM_DTR | TIOCM_RTS;
619 		mct_u232_set_modem_ctrl(port, control_state);
620 	}
621 
622 	mct_u232_set_baud_rate(tty, serial, port, tty_get_baud_rate(tty));
623 
624 	if ((cflag & CBAUD) == B0) {
625 		dev_dbg(&port->dev, "%s: baud is B0\n", __func__);
626 		/* Drop RTS and DTR */
627 		control_state &= ~(TIOCM_DTR | TIOCM_RTS);
628 		mct_u232_set_modem_ctrl(port, control_state);
629 	}
630 
631 	/*
632 	 * Update line control register (LCR)
633 	 */
634 
635 	/* set the parity */
636 	if (cflag & PARENB)
637 		last_lcr |= (cflag & PARODD) ?
638 			MCT_U232_PARITY_ODD : MCT_U232_PARITY_EVEN;
639 	else
640 		last_lcr |= MCT_U232_PARITY_NONE;
641 
642 	/* set the number of data bits */
643 	switch (cflag & CSIZE) {
644 	case CS5:
645 		last_lcr |= MCT_U232_DATA_BITS_5; break;
646 	case CS6:
647 		last_lcr |= MCT_U232_DATA_BITS_6; break;
648 	case CS7:
649 		last_lcr |= MCT_U232_DATA_BITS_7; break;
650 	case CS8:
651 		last_lcr |= MCT_U232_DATA_BITS_8; break;
652 	default:
653 		dev_err(&port->dev,
654 			"CSIZE was not CS5-CS8, using default of 8\n");
655 		last_lcr |= MCT_U232_DATA_BITS_8;
656 		break;
657 	}
658 
659 	termios->c_cflag &= ~CMSPAR;
660 
661 	/* set the number of stop bits */
662 	last_lcr |= (cflag & CSTOPB) ?
663 		MCT_U232_STOP_BITS_2 : MCT_U232_STOP_BITS_1;
664 
665 	mct_u232_set_line_ctrl(port, last_lcr);
666 
667 	/* save off the modified port settings */
668 	spin_lock_irqsave(&priv->lock, flags);
669 	priv->control_state = control_state;
670 	priv->last_lcr = last_lcr;
671 	spin_unlock_irqrestore(&priv->lock, flags);
672 } /* mct_u232_set_termios */
673 
674 static void mct_u232_break_ctl(struct tty_struct *tty, int break_state)
675 {
676 	struct usb_serial_port *port = tty->driver_data;
677 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
678 	unsigned char lcr;
679 	unsigned long flags;
680 
681 	spin_lock_irqsave(&priv->lock, flags);
682 	lcr = priv->last_lcr;
683 
684 	if (break_state)
685 		lcr |= MCT_U232_SET_BREAK;
686 	spin_unlock_irqrestore(&priv->lock, flags);
687 
688 	mct_u232_set_line_ctrl(port, lcr);
689 } /* mct_u232_break_ctl */
690 
691 
692 static int mct_u232_tiocmget(struct tty_struct *tty)
693 {
694 	struct usb_serial_port *port = tty->driver_data;
695 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
696 	unsigned int control_state;
697 	unsigned long flags;
698 
699 	spin_lock_irqsave(&priv->lock, flags);
700 	control_state = priv->control_state;
701 	spin_unlock_irqrestore(&priv->lock, flags);
702 
703 	return control_state;
704 }
705 
706 static int mct_u232_tiocmset(struct tty_struct *tty,
707 			      unsigned int set, unsigned int clear)
708 {
709 	struct usb_serial_port *port = tty->driver_data;
710 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
711 	unsigned int control_state;
712 	unsigned long flags;
713 
714 	spin_lock_irqsave(&priv->lock, flags);
715 	control_state = priv->control_state;
716 
717 	if (set & TIOCM_RTS)
718 		control_state |= TIOCM_RTS;
719 	if (set & TIOCM_DTR)
720 		control_state |= TIOCM_DTR;
721 	if (clear & TIOCM_RTS)
722 		control_state &= ~TIOCM_RTS;
723 	if (clear & TIOCM_DTR)
724 		control_state &= ~TIOCM_DTR;
725 
726 	priv->control_state = control_state;
727 	spin_unlock_irqrestore(&priv->lock, flags);
728 	return mct_u232_set_modem_ctrl(port, control_state);
729 }
730 
731 static void mct_u232_throttle(struct tty_struct *tty)
732 {
733 	struct usb_serial_port *port = tty->driver_data;
734 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
735 	unsigned int control_state;
736 
737 	spin_lock_irq(&priv->lock);
738 	priv->rx_flags |= THROTTLED;
739 	if (C_CRTSCTS(tty)) {
740 		priv->control_state &= ~TIOCM_RTS;
741 		control_state = priv->control_state;
742 		spin_unlock_irq(&priv->lock);
743 		mct_u232_set_modem_ctrl(port, control_state);
744 	} else {
745 		spin_unlock_irq(&priv->lock);
746 	}
747 }
748 
749 static void mct_u232_unthrottle(struct tty_struct *tty)
750 {
751 	struct usb_serial_port *port = tty->driver_data;
752 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
753 	unsigned int control_state;
754 
755 	spin_lock_irq(&priv->lock);
756 	if ((priv->rx_flags & THROTTLED) && C_CRTSCTS(tty)) {
757 		priv->rx_flags &= ~THROTTLED;
758 		priv->control_state |= TIOCM_RTS;
759 		control_state = priv->control_state;
760 		spin_unlock_irq(&priv->lock);
761 		mct_u232_set_modem_ctrl(port, control_state);
762 	} else {
763 		spin_unlock_irq(&priv->lock);
764 	}
765 }
766 
767 module_usb_serial_driver(serial_drivers, id_table);
768 
769 MODULE_AUTHOR(DRIVER_AUTHOR);
770 MODULE_DESCRIPTION(DRIVER_DESC);
771 MODULE_LICENSE("GPL");
772