xref: /linux/drivers/usb/serial/mct_u232.c (revision 2277ab4a1df50e05bc732fe9488d4e902bb8399a)
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  * TEST STATUS:
24  *   Basic tests have been performed with minicom/zmodem transfers and
25  *   modem dialing under Linux 2.4.0-test10 (for me it works fine).
26  *
27  * 04-Nov-2003 Bill Marr <marr at flex dot com>
28  *   - Mimic Windows driver by sending 2 USB 'device request' messages
29  *     following normal 'baud rate change' message.  This allows data to be
30  *     transmitted to RS-232 devices which don't assert the 'CTS' signal.
31  *
32  * 10-Nov-2001 Wolfgang Grandegger
33  *   - Fixed an endianess problem with the baudrate selection for PowerPC.
34  *
35  * 06-Dec-2001 Martin Hamilton <martinh@gnu.org>
36  *   - Added support for the Belkin F5U109 DB9 adaptor
37  *
38  * 30-May-2001 Greg Kroah-Hartman
39  *   - switched from using spinlock to a semaphore, which fixes lots of
40  *     problems.
41  *
42  * 04-May-2001 Stelian Pop
43  *   - Set the maximum bulk output size for Sitecom U232-P25 model to 16 bytes
44  *     instead of the device reported 32 (using 32 bytes causes many data
45  *     loss, Windows driver uses 16 too).
46  *
47  * 02-May-2001 Stelian Pop
48  *   - Fixed the baud calculation for Sitecom U232-P25 model
49  *
50  * 08-Apr-2001 gb
51  *   - Identify version on module load.
52  *
53  * 06-Jan-2001 Cornel Ciocirlan
54  *   - Added support for Sitecom U232-P25 model (Product Id 0x0230)
55  *   - Added support for D-Link DU-H3SP USB BAY (Product Id 0x0200)
56  *
57  * 29-Nov-2000 Greg Kroah-Hartman
58  *   - Added device id table to fit with 2.4.0-test11 structure.
59  *   - took out DEAL_WITH_TWO_INT_IN_ENDPOINTS #define as it's not needed
60  *     (lots of things will change if/when the usb-serial core changes to
61  *     handle these issues.
62  *
63  * 27-Nov-2000 Wolfgang Grandegge
64  *   A version for kernel 2.4.0-test10 released to the Linux community
65  *   (via linux-usb-devel).
66  */
67 
68 #include <linux/kernel.h>
69 #include <linux/errno.h>
70 #include <linux/init.h>
71 #include <linux/slab.h>
72 #include <linux/tty.h>
73 #include <linux/tty_driver.h>
74 #include <linux/tty_flip.h>
75 #include <linux/module.h>
76 #include <linux/spinlock.h>
77 #include <linux/uaccess.h>
78 #include <linux/usb.h>
79 #include <linux/usb/serial.h>
80 #include "mct_u232.h"
81 
82 /*
83  * Version Information
84  */
85 #define DRIVER_VERSION "z2.1"		/* Linux in-kernel version */
86 #define DRIVER_AUTHOR "Wolfgang Grandegger <wolfgang@ces.ch>"
87 #define DRIVER_DESC "Magic Control Technology USB-RS232 converter driver"
88 
89 static int debug;
90 
91 /*
92  * Function prototypes
93  */
94 static int  mct_u232_startup(struct usb_serial *serial);
95 static void mct_u232_release(struct usb_serial *serial);
96 static int  mct_u232_open(struct tty_struct *tty,
97 			struct usb_serial_port *port, struct file *filp);
98 static void mct_u232_close(struct usb_serial_port *port);
99 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on);
100 static void mct_u232_read_int_callback(struct urb *urb);
101 static void mct_u232_set_termios(struct tty_struct *tty,
102 			struct usb_serial_port *port, struct ktermios *old);
103 static void mct_u232_break_ctl(struct tty_struct *tty, int break_state);
104 static int  mct_u232_tiocmget(struct tty_struct *tty, struct file *file);
105 static int  mct_u232_tiocmset(struct tty_struct *tty, struct file *file,
106 			unsigned int set, unsigned int clear);
107 static void mct_u232_throttle(struct tty_struct *tty);
108 static void mct_u232_unthrottle(struct tty_struct *tty);
109 
110 
111 /*
112  * All of the device info needed for the MCT USB-RS232 converter.
113  */
114 static struct usb_device_id id_table_combined [] = {
115 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_PID) },
116 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_SITECOM_PID) },
117 	{ USB_DEVICE(MCT_U232_VID, MCT_U232_DU_H3SP_PID) },
118 	{ USB_DEVICE(MCT_U232_BELKIN_F5U109_VID, MCT_U232_BELKIN_F5U109_PID) },
119 	{ }		/* Terminating entry */
120 };
121 
122 MODULE_DEVICE_TABLE(usb, id_table_combined);
123 
124 static struct usb_driver mct_u232_driver = {
125 	.name =		"mct_u232",
126 	.probe =	usb_serial_probe,
127 	.disconnect =	usb_serial_disconnect,
128 	.id_table =	id_table_combined,
129 	.no_dynamic_id = 	1,
130 };
131 
132 static struct usb_serial_driver mct_u232_device = {
133 	.driver = {
134 		.owner =	THIS_MODULE,
135 		.name =		"mct_u232",
136 	},
137 	.description =	     "MCT U232",
138 	.usb_driver = 	     &mct_u232_driver,
139 	.id_table =	     id_table_combined,
140 	.num_ports =	     1,
141 	.open =		     mct_u232_open,
142 	.close =	     mct_u232_close,
143 	.dtr_rts =	     mct_u232_dtr_rts,
144 	.throttle =	     mct_u232_throttle,
145 	.unthrottle =	     mct_u232_unthrottle,
146 	.read_int_callback = mct_u232_read_int_callback,
147 	.set_termios =	     mct_u232_set_termios,
148 	.break_ctl =	     mct_u232_break_ctl,
149 	.tiocmget =	     mct_u232_tiocmget,
150 	.tiocmset =	     mct_u232_tiocmset,
151 	.attach =	     mct_u232_startup,
152 	.release =	     mct_u232_release,
153 };
154 
155 
156 struct mct_u232_private {
157 	spinlock_t lock;
158 	unsigned int	     control_state; /* Modem Line Setting (TIOCM) */
159 	unsigned char        last_lcr;      /* Line Control Register */
160 	unsigned char	     last_lsr;      /* Line Status Register */
161 	unsigned char	     last_msr;      /* Modem Status Register */
162 	unsigned int	     rx_flags;      /* Throttling flags */
163 };
164 
165 #define THROTTLED		0x01
166 
167 /*
168  * Handle vendor specific USB requests
169  */
170 
171 #define WDR_TIMEOUT 5000 /* default urb timeout */
172 
173 /*
174  * Later day 2.6.0-test kernels have new baud rates like B230400 which
175  * we do not know how to support. We ignore them for the moment.
176  */
177 static int mct_u232_calculate_baud_rate(struct usb_serial *serial,
178 					speed_t value, speed_t *result)
179 {
180 	*result = value;
181 
182 	if (le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_SITECOM_PID
183 		|| le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_BELKIN_F5U109_PID) {
184 		switch (value) {
185 		case 300:
186 			return 0x01;
187 		case 600:
188 			return 0x02; /* this one not tested */
189 		case 1200:
190 			return 0x03;
191 		case 2400:
192 			return 0x04;
193 		case 4800:
194 			return 0x06;
195 		case 9600:
196 			return 0x08;
197 		case 19200:
198 			return 0x09;
199 		case 38400:
200 			return 0x0a;
201 		case 57600:
202 			return 0x0b;
203 		case 115200:
204 			return 0x0c;
205 		default:
206 			*result = 9600;
207 			return 0x08;
208 		}
209 	} else {
210 		/* FIXME: Can we use any divider - should we do
211 		   divider = 115200/value;
212 		   real baud = 115200/divider */
213 		switch (value) {
214 		case 300: break;
215 		case 600: break;
216 		case 1200: break;
217 		case 2400: break;
218 		case 4800: break;
219 		case 9600: break;
220 		case 19200: break;
221 		case 38400: break;
222 		case 57600: break;
223 		case 115200: break;
224 		default:
225 			value = 9600;
226 			*result = 9600;
227 		}
228 		return 115200/value;
229 	}
230 }
231 
232 static int mct_u232_set_baud_rate(struct tty_struct *tty,
233 	struct usb_serial *serial, struct usb_serial_port *port, speed_t value)
234 {
235 	__le32 divisor;
236 	int rc;
237 	unsigned char zero_byte = 0;
238 	unsigned char cts_enable_byte = 0;
239 	speed_t speed;
240 
241 	divisor = cpu_to_le32(mct_u232_calculate_baud_rate(serial, value,
242 								&speed));
243 
244 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
245 				MCT_U232_SET_BAUD_RATE_REQUEST,
246 				MCT_U232_SET_REQUEST_TYPE,
247 				0, 0, &divisor, MCT_U232_SET_BAUD_RATE_SIZE,
248 				WDR_TIMEOUT);
249 	if (rc < 0)	/*FIXME: What value speed results */
250 		dev_err(&port->dev, "Set BAUD RATE %d failed (error = %d)\n",
251 			value, rc);
252 	else
253 		tty_encode_baud_rate(tty, speed, speed);
254 	dbg("set_baud_rate: value: 0x%x, divisor: 0x%x", value, divisor);
255 
256 	/* Mimic the MCT-supplied Windows driver (version 1.21P.0104), which
257 	   always sends two extra USB 'device request' messages after the
258 	   'baud rate change' message.  The actual functionality of the
259 	   request codes in these messages is not fully understood but these
260 	   particular codes are never seen in any operation besides a baud
261 	   rate change.  Both of these messages send a single byte of data.
262 	   In the first message, the value of this byte is always zero.
263 
264 	   The second message has been determined experimentally to control
265 	   whether data will be transmitted to a device which is not asserting
266 	   the 'CTS' signal.  If the second message's data byte is zero, data
267 	   will be transmitted even if 'CTS' is not asserted (i.e. no hardware
268 	   flow control).  if the second message's data byte is nonzero (a
269 	   value of 1 is used by this driver), data will not be transmitted to
270 	   a device which is not asserting 'CTS'.
271 	*/
272 
273 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
274 				MCT_U232_SET_UNKNOWN1_REQUEST,
275 				MCT_U232_SET_REQUEST_TYPE,
276 				0, 0, &zero_byte, MCT_U232_SET_UNKNOWN1_SIZE,
277 				WDR_TIMEOUT);
278 	if (rc < 0)
279 		dev_err(&port->dev, "Sending USB device request code %d "
280 			"failed (error = %d)\n", MCT_U232_SET_UNKNOWN1_REQUEST,
281 			rc);
282 
283 	if (port && C_CRTSCTS(tty))
284 	   cts_enable_byte = 1;
285 
286 	dbg("set_baud_rate: send second control message, data = %02X",
287 							cts_enable_byte);
288 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
289 			MCT_U232_SET_CTS_REQUEST,
290 			MCT_U232_SET_REQUEST_TYPE,
291 			0, 0, &cts_enable_byte, MCT_U232_SET_CTS_SIZE,
292 			WDR_TIMEOUT);
293 	if (rc < 0)
294 		dev_err(&port->dev, "Sending USB device request code %d "
295 			"failed (error = %d)\n", MCT_U232_SET_CTS_REQUEST, rc);
296 
297 	return rc;
298 } /* mct_u232_set_baud_rate */
299 
300 static int mct_u232_set_line_ctrl(struct usb_serial *serial, unsigned char lcr)
301 {
302 	int rc;
303 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
304 			MCT_U232_SET_LINE_CTRL_REQUEST,
305 			MCT_U232_SET_REQUEST_TYPE,
306 			0, 0, &lcr, MCT_U232_SET_LINE_CTRL_SIZE,
307 			WDR_TIMEOUT);
308 	if (rc < 0)
309 		dev_err(&serial->dev->dev,
310 			"Set LINE CTRL 0x%x failed (error = %d)\n", lcr, rc);
311 	dbg("set_line_ctrl: 0x%x", lcr);
312 	return rc;
313 } /* mct_u232_set_line_ctrl */
314 
315 static int mct_u232_set_modem_ctrl(struct usb_serial *serial,
316 				   unsigned int control_state)
317 {
318 	int rc;
319 	unsigned char mcr = MCT_U232_MCR_NONE;
320 
321 	if (control_state & TIOCM_DTR)
322 		mcr |= MCT_U232_MCR_DTR;
323 	if (control_state & TIOCM_RTS)
324 		mcr |= MCT_U232_MCR_RTS;
325 
326 	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
327 			MCT_U232_SET_MODEM_CTRL_REQUEST,
328 			MCT_U232_SET_REQUEST_TYPE,
329 			0, 0, &mcr, MCT_U232_SET_MODEM_CTRL_SIZE,
330 			WDR_TIMEOUT);
331 	if (rc < 0)
332 		dev_err(&serial->dev->dev,
333 			"Set MODEM CTRL 0x%x failed (error = %d)\n", mcr, rc);
334 	dbg("set_modem_ctrl: state=0x%x ==> mcr=0x%x", control_state, mcr);
335 
336 	return rc;
337 } /* mct_u232_set_modem_ctrl */
338 
339 static int mct_u232_get_modem_stat(struct usb_serial *serial,
340 						unsigned char *msr)
341 {
342 	int rc;
343 	rc = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
344 			MCT_U232_GET_MODEM_STAT_REQUEST,
345 			MCT_U232_GET_REQUEST_TYPE,
346 			0, 0, msr, MCT_U232_GET_MODEM_STAT_SIZE,
347 			WDR_TIMEOUT);
348 	if (rc < 0) {
349 		dev_err(&serial->dev->dev,
350 			"Get MODEM STATus failed (error = %d)\n", rc);
351 		*msr = 0;
352 	}
353 	dbg("get_modem_stat: 0x%x", *msr);
354 	return rc;
355 } /* mct_u232_get_modem_stat */
356 
357 static void mct_u232_msr_to_state(unsigned int *control_state,
358 						unsigned char msr)
359 {
360 	/* Translate Control Line states */
361 	if (msr & MCT_U232_MSR_DSR)
362 		*control_state |=  TIOCM_DSR;
363 	else
364 		*control_state &= ~TIOCM_DSR;
365 	if (msr & MCT_U232_MSR_CTS)
366 		*control_state |=  TIOCM_CTS;
367 	else
368 		*control_state &= ~TIOCM_CTS;
369 	if (msr & MCT_U232_MSR_RI)
370 		*control_state |=  TIOCM_RI;
371 	else
372 		*control_state &= ~TIOCM_RI;
373 	if (msr & MCT_U232_MSR_CD)
374 		*control_state |=  TIOCM_CD;
375 	else
376 		*control_state &= ~TIOCM_CD;
377 	dbg("msr_to_state: msr=0x%x ==> state=0x%x", msr, *control_state);
378 } /* mct_u232_msr_to_state */
379 
380 /*
381  * Driver's tty interface functions
382  */
383 
384 static int mct_u232_startup(struct usb_serial *serial)
385 {
386 	struct mct_u232_private *priv;
387 	struct usb_serial_port *port, *rport;
388 
389 	priv = kzalloc(sizeof(struct mct_u232_private), GFP_KERNEL);
390 	if (!priv)
391 		return -ENOMEM;
392 	spin_lock_init(&priv->lock);
393 	usb_set_serial_port_data(serial->port[0], priv);
394 
395 	init_waitqueue_head(&serial->port[0]->write_wait);
396 
397 	/* Puh, that's dirty */
398 	port = serial->port[0];
399 	rport = serial->port[1];
400 	/* No unlinking, it wasn't submitted yet. */
401 	usb_free_urb(port->read_urb);
402 	port->read_urb = rport->interrupt_in_urb;
403 	rport->interrupt_in_urb = NULL;
404 	port->read_urb->context = port;
405 
406 	return 0;
407 } /* mct_u232_startup */
408 
409 
410 static void mct_u232_release(struct usb_serial *serial)
411 {
412 	struct mct_u232_private *priv;
413 	int i;
414 
415 	dbg("%s", __func__);
416 
417 	for (i = 0; i < serial->num_ports; ++i) {
418 		/* My special items, the standard routines free my urbs */
419 		priv = usb_get_serial_port_data(serial->port[i]);
420 		kfree(priv);
421 	}
422 } /* mct_u232_release */
423 
424 static int  mct_u232_open(struct tty_struct *tty,
425 			struct usb_serial_port *port, struct file *filp)
426 {
427 	struct usb_serial *serial = port->serial;
428 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
429 	int retval = 0;
430 	unsigned int control_state;
431 	unsigned long flags;
432 	unsigned char last_lcr;
433 	unsigned char last_msr;
434 
435 	dbg("%s port %d", __func__, port->number);
436 
437 	/* Compensate for a hardware bug: although the Sitecom U232-P25
438 	 * device reports a maximum output packet size of 32 bytes,
439 	 * it seems to be able to accept only 16 bytes (and that's what
440 	 * SniffUSB says too...)
441 	 */
442 	if (le16_to_cpu(serial->dev->descriptor.idProduct)
443 						== MCT_U232_SITECOM_PID)
444 		port->bulk_out_size = 16;
445 
446 	/* Do a defined restart: the normal serial device seems to
447 	 * always turn on DTR and RTS here, so do the same. I'm not
448 	 * sure if this is really necessary. But it should not harm
449 	 * either.
450 	 */
451 	spin_lock_irqsave(&priv->lock, flags);
452 	if (tty && (tty->termios->c_cflag & CBAUD))
453 		priv->control_state = TIOCM_DTR | TIOCM_RTS;
454 	else
455 		priv->control_state = 0;
456 
457 	priv->last_lcr = (MCT_U232_DATA_BITS_8 |
458 			  MCT_U232_PARITY_NONE |
459 			  MCT_U232_STOP_BITS_1);
460 	control_state = priv->control_state;
461 	last_lcr = priv->last_lcr;
462 	spin_unlock_irqrestore(&priv->lock, flags);
463 	mct_u232_set_modem_ctrl(serial, control_state);
464 	mct_u232_set_line_ctrl(serial, last_lcr);
465 
466 	/* Read modem status and update control state */
467 	mct_u232_get_modem_stat(serial, &last_msr);
468 	spin_lock_irqsave(&priv->lock, flags);
469 	priv->last_msr = last_msr;
470 	mct_u232_msr_to_state(&priv->control_state, priv->last_msr);
471 	spin_unlock_irqrestore(&priv->lock, flags);
472 
473 	port->read_urb->dev = port->serial->dev;
474 	retval = usb_submit_urb(port->read_urb, GFP_KERNEL);
475 	if (retval) {
476 		dev_err(&port->dev,
477 			"usb_submit_urb(read bulk) failed pipe 0x%x err %d\n",
478 			port->read_urb->pipe, retval);
479 		goto error;
480 	}
481 
482 	port->interrupt_in_urb->dev = port->serial->dev;
483 	retval = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
484 	if (retval) {
485 		usb_kill_urb(port->read_urb);
486 		dev_err(&port->dev,
487 			"usb_submit_urb(read int) failed pipe 0x%x err %d",
488 			port->interrupt_in_urb->pipe, retval);
489 		goto error;
490 	}
491 	return 0;
492 
493 error:
494 	return retval;
495 } /* mct_u232_open */
496 
497 static void mct_u232_dtr_rts(struct usb_serial_port *port, int on)
498 {
499 	unsigned int control_state;
500 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
501 
502 	mutex_lock(&port->serial->disc_mutex);
503 	if (!port->serial->disconnected) {
504 		/* drop DTR and RTS */
505 		spin_lock_irq(&priv->lock);
506 		if (on)
507 			priv->control_state |= TIOCM_DTR | TIOCM_RTS;
508 		else
509 			priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
510 		control_state = priv->control_state;
511 		spin_unlock_irq(&priv->lock);
512 		mct_u232_set_modem_ctrl(port->serial, control_state);
513 	}
514 	mutex_unlock(&port->serial->disc_mutex);
515 }
516 
517 static void mct_u232_close(struct usb_serial_port *port)
518 {
519 	dbg("%s port %d", __func__, port->number);
520 
521 	if (port->serial->dev) {
522 		/* shutdown our urbs */
523 		usb_kill_urb(port->write_urb);
524 		usb_kill_urb(port->read_urb);
525 		usb_kill_urb(port->interrupt_in_urb);
526 	}
527 } /* mct_u232_close */
528 
529 
530 static void mct_u232_read_int_callback(struct urb *urb)
531 {
532 	struct usb_serial_port *port = urb->context;
533 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
534 	struct usb_serial *serial = port->serial;
535 	struct tty_struct *tty;
536 	unsigned char *data = urb->transfer_buffer;
537 	int retval;
538 	int status = urb->status;
539 	unsigned long flags;
540 
541 	switch (status) {
542 	case 0:
543 		/* success */
544 		break;
545 	case -ECONNRESET:
546 	case -ENOENT:
547 	case -ESHUTDOWN:
548 		/* this urb is terminated, clean up */
549 		dbg("%s - urb shutting down with status: %d",
550 		    __func__, status);
551 		return;
552 	default:
553 		dbg("%s - nonzero urb status received: %d",
554 		    __func__, status);
555 		goto exit;
556 	}
557 
558 	if (!serial) {
559 		dbg("%s - bad serial pointer, exiting", __func__);
560 		return;
561 	}
562 
563 	dbg("%s - port %d", __func__, port->number);
564 	usb_serial_debug_data(debug, &port->dev, __func__,
565 					urb->actual_length, data);
566 
567 	/*
568 	 * Work-a-round: handle the 'usual' bulk-in pipe here
569 	 */
570 	if (urb->transfer_buffer_length > 2) {
571 		tty = tty_port_tty_get(&port->port);
572 		if (urb->actual_length) {
573 			tty_insert_flip_string(tty, data, urb->actual_length);
574 			tty_flip_buffer_push(tty);
575 			tty_kref_put(tty);
576 		}
577 		goto exit;
578 	}
579 
580 	/*
581 	 * The interrupt-in pipe signals exceptional conditions (modem line
582 	 * signal changes and errors). data[0] holds MSR, data[1] holds LSR.
583 	 */
584 	spin_lock_irqsave(&priv->lock, flags);
585 	priv->last_msr = data[MCT_U232_MSR_INDEX];
586 
587 	/* Record Control Line states */
588 	mct_u232_msr_to_state(&priv->control_state, priv->last_msr);
589 
590 #if 0
591 	/* Not yet handled. See belkin_sa.c for further information */
592 	/* Now to report any errors */
593 	priv->last_lsr = data[MCT_U232_LSR_INDEX];
594 	/*
595 	 * fill in the flip buffer here, but I do not know the relation
596 	 * to the current/next receive buffer or characters.  I need
597 	 * to look in to this before committing any code.
598 	 */
599 	if (priv->last_lsr & MCT_U232_LSR_ERR) {
600 		tty = tty_port_tty_get(&port->port);
601 		/* Overrun Error */
602 		if (priv->last_lsr & MCT_U232_LSR_OE) {
603 		}
604 		/* Parity Error */
605 		if (priv->last_lsr & MCT_U232_LSR_PE) {
606 		}
607 		/* Framing Error */
608 		if (priv->last_lsr & MCT_U232_LSR_FE) {
609 		}
610 		/* Break Indicator */
611 		if (priv->last_lsr & MCT_U232_LSR_BI) {
612 		}
613 		tty_kref_put(tty);
614 	}
615 #endif
616 	spin_unlock_irqrestore(&priv->lock, flags);
617 exit:
618 	retval = usb_submit_urb(urb, GFP_ATOMIC);
619 	if (retval)
620 		dev_err(&port->dev,
621 			"%s - usb_submit_urb failed with result %d\n",
622 			__func__, retval);
623 } /* mct_u232_read_int_callback */
624 
625 static void mct_u232_set_termios(struct tty_struct *tty,
626 				 struct usb_serial_port *port,
627 				 struct ktermios *old_termios)
628 {
629 	struct usb_serial *serial = port->serial;
630 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
631 	struct ktermios *termios = tty->termios;
632 	unsigned int cflag = termios->c_cflag;
633 	unsigned int old_cflag = old_termios->c_cflag;
634 	unsigned long flags;
635 	unsigned int control_state;
636 	unsigned char last_lcr;
637 
638 	/* get a local copy of the current port settings */
639 	spin_lock_irqsave(&priv->lock, flags);
640 	control_state = priv->control_state;
641 	spin_unlock_irqrestore(&priv->lock, flags);
642 	last_lcr = 0;
643 
644 	/*
645 	 * Update baud rate.
646 	 * Do not attempt to cache old rates and skip settings,
647 	 * disconnects screw such tricks up completely.
648 	 * Premature optimization is the root of all evil.
649 	 */
650 
651 	/* reassert DTR and RTS on transition from B0 */
652 	if ((old_cflag & CBAUD) == B0) {
653 		dbg("%s: baud was B0", __func__);
654 		control_state |= TIOCM_DTR | TIOCM_RTS;
655 		mct_u232_set_modem_ctrl(serial, control_state);
656 	}
657 
658 	mct_u232_set_baud_rate(tty, serial, port, tty_get_baud_rate(tty));
659 
660 	if ((cflag & CBAUD) == B0) {
661 		dbg("%s: baud is B0", __func__);
662 		/* Drop RTS and DTR */
663 		control_state &= ~(TIOCM_DTR | TIOCM_RTS);
664 		mct_u232_set_modem_ctrl(serial, control_state);
665 	}
666 
667 	/*
668 	 * Update line control register (LCR)
669 	 */
670 
671 	/* set the parity */
672 	if (cflag & PARENB)
673 		last_lcr |= (cflag & PARODD) ?
674 			MCT_U232_PARITY_ODD : MCT_U232_PARITY_EVEN;
675 	else
676 		last_lcr |= MCT_U232_PARITY_NONE;
677 
678 	/* set the number of data bits */
679 	switch (cflag & CSIZE) {
680 	case CS5:
681 		last_lcr |= MCT_U232_DATA_BITS_5; break;
682 	case CS6:
683 		last_lcr |= MCT_U232_DATA_BITS_6; break;
684 	case CS7:
685 		last_lcr |= MCT_U232_DATA_BITS_7; break;
686 	case CS8:
687 		last_lcr |= MCT_U232_DATA_BITS_8; break;
688 	default:
689 		dev_err(&port->dev,
690 			"CSIZE was not CS5-CS8, using default of 8\n");
691 		last_lcr |= MCT_U232_DATA_BITS_8;
692 		break;
693 	}
694 
695 	termios->c_cflag &= ~CMSPAR;
696 
697 	/* set the number of stop bits */
698 	last_lcr |= (cflag & CSTOPB) ?
699 		MCT_U232_STOP_BITS_2 : MCT_U232_STOP_BITS_1;
700 
701 	mct_u232_set_line_ctrl(serial, last_lcr);
702 
703 	/* save off the modified port settings */
704 	spin_lock_irqsave(&priv->lock, flags);
705 	priv->control_state = control_state;
706 	priv->last_lcr = last_lcr;
707 	spin_unlock_irqrestore(&priv->lock, flags);
708 } /* mct_u232_set_termios */
709 
710 static void mct_u232_break_ctl(struct tty_struct *tty, int break_state)
711 {
712 	struct usb_serial_port *port = tty->driver_data;
713 	struct usb_serial *serial = port->serial;
714 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
715 	unsigned char lcr;
716 	unsigned long flags;
717 
718 	dbg("%sstate=%d", __func__, break_state);
719 
720 	spin_lock_irqsave(&priv->lock, flags);
721 	lcr = priv->last_lcr;
722 
723 	if (break_state)
724 		lcr |= MCT_U232_SET_BREAK;
725 	spin_unlock_irqrestore(&priv->lock, flags);
726 
727 	mct_u232_set_line_ctrl(serial, lcr);
728 } /* mct_u232_break_ctl */
729 
730 
731 static int mct_u232_tiocmget(struct tty_struct *tty, struct file *file)
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 	unsigned long flags;
737 
738 	dbg("%s", __func__);
739 
740 	spin_lock_irqsave(&priv->lock, flags);
741 	control_state = priv->control_state;
742 	spin_unlock_irqrestore(&priv->lock, flags);
743 
744 	return control_state;
745 }
746 
747 static int mct_u232_tiocmset(struct tty_struct *tty, struct file *file,
748 			      unsigned int set, unsigned int clear)
749 {
750 	struct usb_serial_port *port = tty->driver_data;
751 	struct usb_serial *serial = port->serial;
752 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
753 	unsigned int control_state;
754 	unsigned long flags;
755 
756 	dbg("%s", __func__);
757 
758 	spin_lock_irqsave(&priv->lock, flags);
759 	control_state = priv->control_state;
760 
761 	if (set & TIOCM_RTS)
762 		control_state |= TIOCM_RTS;
763 	if (set & TIOCM_DTR)
764 		control_state |= TIOCM_DTR;
765 	if (clear & TIOCM_RTS)
766 		control_state &= ~TIOCM_RTS;
767 	if (clear & TIOCM_DTR)
768 		control_state &= ~TIOCM_DTR;
769 
770 	priv->control_state = control_state;
771 	spin_unlock_irqrestore(&priv->lock, flags);
772 	return mct_u232_set_modem_ctrl(serial, control_state);
773 }
774 
775 static void mct_u232_throttle(struct tty_struct *tty)
776 {
777 	struct usb_serial_port *port = tty->driver_data;
778 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
779 	unsigned long flags;
780 	unsigned int control_state;
781 
782 	dbg("%s - port %d", __func__, port->number);
783 
784 	spin_lock_irqsave(&priv->lock, flags);
785 	priv->rx_flags |= THROTTLED;
786 	if (C_CRTSCTS(tty)) {
787 		priv->control_state &= ~TIOCM_RTS;
788 		control_state = priv->control_state;
789 		spin_unlock_irqrestore(&priv->lock, flags);
790 		(void) mct_u232_set_modem_ctrl(port->serial, control_state);
791 	} else {
792 		spin_unlock_irqrestore(&priv->lock, flags);
793 	}
794 }
795 
796 
797 static void mct_u232_unthrottle(struct tty_struct *tty)
798 {
799 	struct usb_serial_port *port = tty->driver_data;
800 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
801 	unsigned long flags;
802 	unsigned int control_state;
803 
804 	dbg("%s - port %d", __func__, port->number);
805 
806 	spin_lock_irqsave(&priv->lock, flags);
807 	if ((priv->rx_flags & THROTTLED) && C_CRTSCTS(tty)) {
808 		priv->rx_flags &= ~THROTTLED;
809 		priv->control_state |= TIOCM_RTS;
810 		control_state = priv->control_state;
811 		spin_unlock_irqrestore(&priv->lock, flags);
812 		(void) mct_u232_set_modem_ctrl(port->serial, control_state);
813 	} else {
814 		spin_unlock_irqrestore(&priv->lock, flags);
815 	}
816 }
817 
818 static int __init mct_u232_init(void)
819 {
820 	int retval;
821 	retval = usb_serial_register(&mct_u232_device);
822 	if (retval)
823 		goto failed_usb_serial_register;
824 	retval = usb_register(&mct_u232_driver);
825 	if (retval)
826 		goto failed_usb_register;
827 	printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
828 	       DRIVER_DESC "\n");
829 	return 0;
830 failed_usb_register:
831 	usb_serial_deregister(&mct_u232_device);
832 failed_usb_serial_register:
833 	return retval;
834 }
835 
836 
837 static void __exit mct_u232_exit(void)
838 {
839 	usb_deregister(&mct_u232_driver);
840 	usb_serial_deregister(&mct_u232_device);
841 }
842 
843 module_init(mct_u232_init);
844 module_exit(mct_u232_exit);
845 
846 MODULE_AUTHOR(DRIVER_AUTHOR);
847 MODULE_DESCRIPTION(DRIVER_DESC);
848 MODULE_LICENSE("GPL");
849 
850 module_param(debug, bool, S_IRUGO | S_IWUSR);
851 MODULE_PARM_DESC(debug, "Debug enabled or not");
852