xref: /linux/drivers/usb/serial/mct_u232.c (revision 182fff3a2aafe4e7f3717a0be9df2fe2ed1a77de)
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 <linux/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 void 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,
49 				 const struct ktermios *old_termios);
50 static int  mct_u232_break_ctl(struct tty_struct *tty, int break_state);
51 static int  mct_u232_tiocmget(struct tty_struct *tty);
52 static int  mct_u232_tiocmset(struct tty_struct *tty,
53 			unsigned int set, unsigned int clear);
54 static void mct_u232_throttle(struct tty_struct *tty);
55 static void mct_u232_unthrottle(struct tty_struct *tty);
56 
57 
58 /*
59  * All of the device info needed for the MCT USB-RS232 converter.
60  */
61 static const struct usb_device_id id_table[] = {
62 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_PID) },
63 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_SITECOM_PID) },
64 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_DU_H3SP_PID) },
65 	{ USB_DEVICE(MCT_U232_BELKIN_F5U109_VID, MCT_U232_BELKIN_F5U109_PID) },
66 	{ }		/* Terminating entry */
67 };
68 MODULE_DEVICE_TABLE(usb, id_table);
69 
70 static struct usb_serial_driver mct_u232_device = {
71 	.driver = {
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 void 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 
411 static int  mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port)
412 {
413 	struct usb_serial *serial = port->serial;
414 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
415 	int retval = 0;
416 	unsigned int control_state;
417 	unsigned long flags;
418 	unsigned char last_lcr;
419 	unsigned char last_msr;
420 
421 	/* Compensate for a hardware bug: although the Sitecom U232-P25
422 	 * device reports a maximum output packet size of 32 bytes,
423 	 * it seems to be able to accept only 16 bytes (and that's what
424 	 * SniffUSB says too...)
425 	 */
426 	if (le16_to_cpu(serial->dev->descriptor.idProduct)
427 						== MCT_U232_SITECOM_PID)
428 		port->bulk_out_size = 16;
429 
430 	/* Do a defined restart: the normal serial device seems to
431 	 * always turn on DTR and RTS here, so do the same. I'm not
432 	 * sure if this is really necessary. But it should not harm
433 	 * either.
434 	 */
435 	spin_lock_irqsave(&priv->lock, flags);
436 	if (tty && C_BAUD(tty))
437 		priv->control_state = TIOCM_DTR | TIOCM_RTS;
438 	else
439 		priv->control_state = 0;
440 
441 	priv->last_lcr = (MCT_U232_DATA_BITS_8 |
442 			  MCT_U232_PARITY_NONE |
443 			  MCT_U232_STOP_BITS_1);
444 	control_state = priv->control_state;
445 	last_lcr = priv->last_lcr;
446 	spin_unlock_irqrestore(&priv->lock, flags);
447 	mct_u232_set_modem_ctrl(port, control_state);
448 	mct_u232_set_line_ctrl(port, last_lcr);
449 
450 	/* Read modem status and update control state */
451 	mct_u232_get_modem_stat(port, &last_msr);
452 	spin_lock_irqsave(&priv->lock, flags);
453 	priv->last_msr = last_msr;
454 	mct_u232_msr_to_state(port, &priv->control_state, priv->last_msr);
455 	spin_unlock_irqrestore(&priv->lock, flags);
456 
457 	retval = usb_submit_urb(priv->read_urb, GFP_KERNEL);
458 	if (retval) {
459 		dev_err(&port->dev,
460 			"usb_submit_urb(read) failed pipe 0x%x err %d\n",
461 			port->read_urb->pipe, retval);
462 		goto error;
463 	}
464 
465 	retval = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
466 	if (retval) {
467 		usb_kill_urb(priv->read_urb);
468 		dev_err(&port->dev,
469 			"usb_submit_urb(read int) failed pipe 0x%x err %d",
470 			port->interrupt_in_urb->pipe, retval);
471 		goto error;
472 	}
473 	return 0;
474 
475 error:
476 	return retval;
477 } /* mct_u232_open */
478 
479 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on)
480 {
481 	unsigned int control_state;
482 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
483 
484 	spin_lock_irq(&priv->lock);
485 	if (on)
486 		priv->control_state |= TIOCM_DTR | TIOCM_RTS;
487 	else
488 		priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
489 	control_state = priv->control_state;
490 	spin_unlock_irq(&priv->lock);
491 
492 	mct_u232_set_modem_ctrl(port, control_state);
493 }
494 
495 static void mct_u232_close(struct usb_serial_port *port)
496 {
497 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
498 
499 	usb_kill_urb(priv->read_urb);
500 	usb_kill_urb(port->interrupt_in_urb);
501 
502 	usb_serial_generic_close(port);
503 } /* mct_u232_close */
504 
505 
506 static void mct_u232_read_int_callback(struct urb *urb)
507 {
508 	struct usb_serial_port *port = urb->context;
509 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
510 	unsigned char *data = urb->transfer_buffer;
511 	int retval;
512 	int status = urb->status;
513 	unsigned long flags;
514 
515 	switch (status) {
516 	case 0:
517 		/* success */
518 		break;
519 	case -ECONNRESET:
520 	case -ENOENT:
521 	case -ESHUTDOWN:
522 		/* this urb is terminated, clean up */
523 		dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
524 			__func__, status);
525 		return;
526 	default:
527 		dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
528 			__func__, status);
529 		goto exit;
530 	}
531 
532 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
533 
534 	/*
535 	 * Work-a-round: handle the 'usual' bulk-in pipe here
536 	 */
537 	if (urb->transfer_buffer_length > 2) {
538 		if (urb->actual_length) {
539 			tty_insert_flip_string(&port->port, data,
540 					urb->actual_length);
541 			tty_flip_buffer_push(&port->port);
542 		}
543 		goto exit;
544 	}
545 
546 	/*
547 	 * The interrupt-in pipe signals exceptional conditions (modem line
548 	 * signal changes and errors). data[0] holds MSR, data[1] holds LSR.
549 	 */
550 	spin_lock_irqsave(&priv->lock, flags);
551 	priv->last_msr = data[MCT_U232_MSR_INDEX];
552 
553 	/* Record Control Line states */
554 	mct_u232_msr_to_state(port, &priv->control_state, priv->last_msr);
555 
556 	mct_u232_msr_to_icount(&port->icount, priv->last_msr);
557 
558 #if 0
559 	/* Not yet handled. See belkin_sa.c for further information */
560 	/* Now to report any errors */
561 	priv->last_lsr = data[MCT_U232_LSR_INDEX];
562 	/*
563 	 * fill in the flip buffer here, but I do not know the relation
564 	 * to the current/next receive buffer or characters.  I need
565 	 * to look in to this before committing any code.
566 	 */
567 	if (priv->last_lsr & MCT_U232_LSR_ERR) {
568 		tty = tty_port_tty_get(&port->port);
569 		/* Overrun Error */
570 		if (priv->last_lsr & MCT_U232_LSR_OE) {
571 		}
572 		/* Parity Error */
573 		if (priv->last_lsr & MCT_U232_LSR_PE) {
574 		}
575 		/* Framing Error */
576 		if (priv->last_lsr & MCT_U232_LSR_FE) {
577 		}
578 		/* Break Indicator */
579 		if (priv->last_lsr & MCT_U232_LSR_BI) {
580 		}
581 		tty_kref_put(tty);
582 	}
583 #endif
584 	wake_up_interruptible(&port->port.delta_msr_wait);
585 	spin_unlock_irqrestore(&priv->lock, flags);
586 exit:
587 	retval = usb_submit_urb(urb, GFP_ATOMIC);
588 	if (retval)
589 		dev_err(&port->dev,
590 			"%s - usb_submit_urb failed with result %d\n",
591 			__func__, retval);
592 } /* mct_u232_read_int_callback */
593 
594 static void mct_u232_set_termios(struct tty_struct *tty,
595 				 struct usb_serial_port *port,
596 				 const struct ktermios *old_termios)
597 {
598 	struct usb_serial *serial = port->serial;
599 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
600 	struct ktermios *termios = &tty->termios;
601 	unsigned int cflag = termios->c_cflag;
602 	unsigned int old_cflag = old_termios->c_cflag;
603 	unsigned long flags;
604 	unsigned int control_state;
605 	unsigned char last_lcr;
606 
607 	/* get a local copy of the current port settings */
608 	spin_lock_irqsave(&priv->lock, flags);
609 	control_state = priv->control_state;
610 	spin_unlock_irqrestore(&priv->lock, flags);
611 	last_lcr = 0;
612 
613 	/*
614 	 * Update baud rate.
615 	 * Do not attempt to cache old rates and skip settings,
616 	 * disconnects screw such tricks up completely.
617 	 * Premature optimization is the root of all evil.
618 	 */
619 
620 	/* reassert DTR and RTS on transition from B0 */
621 	if ((old_cflag & CBAUD) == B0) {
622 		dev_dbg(&port->dev, "%s: baud was B0\n", __func__);
623 		control_state |= TIOCM_DTR | TIOCM_RTS;
624 		mct_u232_set_modem_ctrl(port, control_state);
625 	}
626 
627 	mct_u232_set_baud_rate(tty, serial, port, tty_get_baud_rate(tty));
628 
629 	if ((cflag & CBAUD) == B0) {
630 		dev_dbg(&port->dev, "%s: baud is B0\n", __func__);
631 		/* Drop RTS and DTR */
632 		control_state &= ~(TIOCM_DTR | TIOCM_RTS);
633 		mct_u232_set_modem_ctrl(port, control_state);
634 	}
635 
636 	/*
637 	 * Update line control register (LCR)
638 	 */
639 
640 	/* set the parity */
641 	if (cflag & PARENB)
642 		last_lcr |= (cflag & PARODD) ?
643 			MCT_U232_PARITY_ODD : MCT_U232_PARITY_EVEN;
644 	else
645 		last_lcr |= MCT_U232_PARITY_NONE;
646 
647 	/* set the number of data bits */
648 	switch (cflag & CSIZE) {
649 	case CS5:
650 		last_lcr |= MCT_U232_DATA_BITS_5; break;
651 	case CS6:
652 		last_lcr |= MCT_U232_DATA_BITS_6; break;
653 	case CS7:
654 		last_lcr |= MCT_U232_DATA_BITS_7; break;
655 	case CS8:
656 		last_lcr |= MCT_U232_DATA_BITS_8; break;
657 	default:
658 		dev_err(&port->dev,
659 			"CSIZE was not CS5-CS8, using default of 8\n");
660 		last_lcr |= MCT_U232_DATA_BITS_8;
661 		break;
662 	}
663 
664 	termios->c_cflag &= ~CMSPAR;
665 
666 	/* set the number of stop bits */
667 	last_lcr |= (cflag & CSTOPB) ?
668 		MCT_U232_STOP_BITS_2 : MCT_U232_STOP_BITS_1;
669 
670 	mct_u232_set_line_ctrl(port, last_lcr);
671 
672 	/* save off the modified port settings */
673 	spin_lock_irqsave(&priv->lock, flags);
674 	priv->control_state = control_state;
675 	priv->last_lcr = last_lcr;
676 	spin_unlock_irqrestore(&priv->lock, flags);
677 } /* mct_u232_set_termios */
678 
679 static int mct_u232_break_ctl(struct tty_struct *tty, int break_state)
680 {
681 	struct usb_serial_port *port = tty->driver_data;
682 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
683 	unsigned char lcr;
684 	unsigned long flags;
685 
686 	spin_lock_irqsave(&priv->lock, flags);
687 	lcr = priv->last_lcr;
688 
689 	if (break_state)
690 		lcr |= MCT_U232_SET_BREAK;
691 	spin_unlock_irqrestore(&priv->lock, flags);
692 
693 	return mct_u232_set_line_ctrl(port, lcr);
694 } /* mct_u232_break_ctl */
695 
696 
697 static int mct_u232_tiocmget(struct tty_struct *tty)
698 {
699 	struct usb_serial_port *port = tty->driver_data;
700 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
701 	unsigned int control_state;
702 	unsigned long flags;
703 
704 	spin_lock_irqsave(&priv->lock, flags);
705 	control_state = priv->control_state;
706 	spin_unlock_irqrestore(&priv->lock, flags);
707 
708 	return control_state;
709 }
710 
711 static int mct_u232_tiocmset(struct tty_struct *tty,
712 			      unsigned int set, unsigned int clear)
713 {
714 	struct usb_serial_port *port = tty->driver_data;
715 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
716 	unsigned int control_state;
717 	unsigned long flags;
718 
719 	spin_lock_irqsave(&priv->lock, flags);
720 	control_state = priv->control_state;
721 
722 	if (set & TIOCM_RTS)
723 		control_state |= TIOCM_RTS;
724 	if (set & TIOCM_DTR)
725 		control_state |= TIOCM_DTR;
726 	if (clear & TIOCM_RTS)
727 		control_state &= ~TIOCM_RTS;
728 	if (clear & TIOCM_DTR)
729 		control_state &= ~TIOCM_DTR;
730 
731 	priv->control_state = control_state;
732 	spin_unlock_irqrestore(&priv->lock, flags);
733 	return mct_u232_set_modem_ctrl(port, control_state);
734 }
735 
736 static void mct_u232_throttle(struct tty_struct *tty)
737 {
738 	struct usb_serial_port *port = tty->driver_data;
739 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
740 	unsigned int control_state;
741 
742 	spin_lock_irq(&priv->lock);
743 	priv->rx_flags |= THROTTLED;
744 	if (C_CRTSCTS(tty)) {
745 		priv->control_state &= ~TIOCM_RTS;
746 		control_state = priv->control_state;
747 		spin_unlock_irq(&priv->lock);
748 		mct_u232_set_modem_ctrl(port, control_state);
749 	} else {
750 		spin_unlock_irq(&priv->lock);
751 	}
752 }
753 
754 static void mct_u232_unthrottle(struct tty_struct *tty)
755 {
756 	struct usb_serial_port *port = tty->driver_data;
757 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
758 	unsigned int control_state;
759 
760 	spin_lock_irq(&priv->lock);
761 	if ((priv->rx_flags & THROTTLED) && C_CRTSCTS(tty)) {
762 		priv->rx_flags &= ~THROTTLED;
763 		priv->control_state |= TIOCM_RTS;
764 		control_state = priv->control_state;
765 		spin_unlock_irq(&priv->lock);
766 		mct_u232_set_modem_ctrl(port, control_state);
767 	} else {
768 		spin_unlock_irq(&priv->lock);
769 	}
770 }
771 
772 module_usb_serial_driver(serial_drivers, id_table);
773 
774 MODULE_AUTHOR(DRIVER_AUTHOR);
775 MODULE_DESCRIPTION(DRIVER_DESC);
776 MODULE_LICENSE("GPL");
777