xref: /openbmc/linux/drivers/usb/serial/cypress_m8.c (revision 7d545e77)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * USB Cypress M8 driver
4  *
5  * 	Copyright (C) 2004
6  * 	    Lonnie Mendez (dignome@gmail.com)
7  *	Copyright (C) 2003,2004
8  *	    Neil Whelchel (koyama@firstlight.net)
9  *
10  * See Documentation/usb/usb-serial.rst for more information on using this
11  * driver
12  *
13  * See http://geocities.com/i0xox0i for information on this driver and the
14  * earthmate usb device.
15  */
16 
17 /* Thanks to Neil Whelchel for writing the first cypress m8 implementation
18    for linux. */
19 /* Thanks to cypress for providing references for the hid reports. */
20 /* Thanks to Jiang Zhang for providing links and for general help. */
21 /* Code originates and was built up from ftdi_sio, belkin, pl2303 and others.*/
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/moduleparam.h>
32 #include <linux/spinlock.h>
33 #include <linux/usb.h>
34 #include <linux/usb/serial.h>
35 #include <linux/serial.h>
36 #include <linux/kfifo.h>
37 #include <linux/delay.h>
38 #include <linux/uaccess.h>
39 #include <asm/unaligned.h>
40 
41 #include "cypress_m8.h"
42 
43 
44 static bool stats;
45 static int interval;
46 static bool unstable_bauds;
47 
48 #define DRIVER_AUTHOR "Lonnie Mendez <dignome@gmail.com>, Neil Whelchel <koyama@firstlight.net>"
49 #define DRIVER_DESC "Cypress USB to Serial Driver"
50 
51 /* write buffer size defines */
52 #define CYPRESS_BUF_SIZE	1024
53 
54 static const struct usb_device_id id_table_earthmate[] = {
55 	{ USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB) },
56 	{ USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB_LT20) },
57 	{ }						/* Terminating entry */
58 };
59 
60 static const struct usb_device_id id_table_cyphidcomrs232[] = {
61 	{ USB_DEVICE(VENDOR_ID_CYPRESS, PRODUCT_ID_CYPHIDCOM) },
62 	{ USB_DEVICE(VENDOR_ID_POWERCOM, PRODUCT_ID_UPS) },
63 	{ USB_DEVICE(VENDOR_ID_FRWD, PRODUCT_ID_CYPHIDCOM_FRWD) },
64 	{ }						/* Terminating entry */
65 };
66 
67 static const struct usb_device_id id_table_nokiaca42v2[] = {
68 	{ USB_DEVICE(VENDOR_ID_DAZZLE, PRODUCT_ID_CA42) },
69 	{ }						/* Terminating entry */
70 };
71 
72 static const struct usb_device_id id_table_combined[] = {
73 	{ USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB) },
74 	{ USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB_LT20) },
75 	{ USB_DEVICE(VENDOR_ID_CYPRESS, PRODUCT_ID_CYPHIDCOM) },
76 	{ USB_DEVICE(VENDOR_ID_POWERCOM, PRODUCT_ID_UPS) },
77 	{ USB_DEVICE(VENDOR_ID_FRWD, PRODUCT_ID_CYPHIDCOM_FRWD) },
78 	{ USB_DEVICE(VENDOR_ID_DAZZLE, PRODUCT_ID_CA42) },
79 	{ }						/* Terminating entry */
80 };
81 
82 MODULE_DEVICE_TABLE(usb, id_table_combined);
83 
84 enum packet_format {
85 	packet_format_1,  /* b0:status, b1:payload count */
86 	packet_format_2   /* b0[7:3]:status, b0[2:0]:payload count */
87 };
88 
89 struct cypress_private {
90 	spinlock_t lock;		   /* private lock */
91 	int chiptype;			   /* identifier of device, for quirks/etc */
92 	int bytes_in;			   /* used for statistics */
93 	int bytes_out;			   /* used for statistics */
94 	int cmd_count;			   /* used for statistics */
95 	int cmd_ctrl;			   /* always set this to 1 before issuing a command */
96 	struct kfifo write_fifo;	   /* write fifo */
97 	int write_urb_in_use;		   /* write urb in use indicator */
98 	int write_urb_interval;            /* interval to use for write urb */
99 	int read_urb_interval;             /* interval to use for read urb */
100 	int comm_is_ok;                    /* true if communication is (still) ok */
101 	__u8 line_control;	   	   /* holds dtr / rts value */
102 	__u8 current_status;	   	   /* received from last read - info on dsr,cts,cd,ri,etc */
103 	__u8 current_config;	   	   /* stores the current configuration byte */
104 	__u8 rx_flags;			   /* throttling - used from whiteheat/ftdi_sio */
105 	enum packet_format pkt_fmt;	   /* format to use for packet send / receive */
106 	int get_cfg_unsafe;		   /* If true, the CYPRESS_GET_CONFIG is unsafe */
107 	int baud_rate;			   /* stores current baud rate in
108 					      integer form */
109 	char prev_status;		   /* used for TIOCMIWAIT */
110 };
111 
112 /* function prototypes for the Cypress USB to serial device */
113 static int  cypress_earthmate_port_probe(struct usb_serial_port *port);
114 static int  cypress_hidcom_port_probe(struct usb_serial_port *port);
115 static int  cypress_ca42v2_port_probe(struct usb_serial_port *port);
116 static int  cypress_port_remove(struct usb_serial_port *port);
117 static int  cypress_open(struct tty_struct *tty, struct usb_serial_port *port);
118 static void cypress_close(struct usb_serial_port *port);
119 static void cypress_dtr_rts(struct usb_serial_port *port, int on);
120 static int  cypress_write(struct tty_struct *tty, struct usb_serial_port *port,
121 			const unsigned char *buf, int count);
122 static void cypress_send(struct usb_serial_port *port);
123 static int  cypress_write_room(struct tty_struct *tty);
124 static void cypress_earthmate_init_termios(struct tty_struct *tty);
125 static void cypress_set_termios(struct tty_struct *tty,
126 			struct usb_serial_port *port, struct ktermios *old);
127 static int  cypress_tiocmget(struct tty_struct *tty);
128 static int  cypress_tiocmset(struct tty_struct *tty,
129 			unsigned int set, unsigned int clear);
130 static int  cypress_chars_in_buffer(struct tty_struct *tty);
131 static void cypress_throttle(struct tty_struct *tty);
132 static void cypress_unthrottle(struct tty_struct *tty);
133 static void cypress_set_dead(struct usb_serial_port *port);
134 static void cypress_read_int_callback(struct urb *urb);
135 static void cypress_write_int_callback(struct urb *urb);
136 
137 static struct usb_serial_driver cypress_earthmate_device = {
138 	.driver = {
139 		.owner =		THIS_MODULE,
140 		.name =			"earthmate",
141 	},
142 	.description =			"DeLorme Earthmate USB",
143 	.id_table =			id_table_earthmate,
144 	.num_ports =			1,
145 	.port_probe =			cypress_earthmate_port_probe,
146 	.port_remove =			cypress_port_remove,
147 	.open =				cypress_open,
148 	.close =			cypress_close,
149 	.dtr_rts =			cypress_dtr_rts,
150 	.write =			cypress_write,
151 	.write_room =			cypress_write_room,
152 	.init_termios =			cypress_earthmate_init_termios,
153 	.set_termios =			cypress_set_termios,
154 	.tiocmget =			cypress_tiocmget,
155 	.tiocmset =			cypress_tiocmset,
156 	.tiocmiwait =			usb_serial_generic_tiocmiwait,
157 	.chars_in_buffer =		cypress_chars_in_buffer,
158 	.throttle =		 	cypress_throttle,
159 	.unthrottle =			cypress_unthrottle,
160 	.read_int_callback =		cypress_read_int_callback,
161 	.write_int_callback =		cypress_write_int_callback,
162 };
163 
164 static struct usb_serial_driver cypress_hidcom_device = {
165 	.driver = {
166 		.owner =		THIS_MODULE,
167 		.name =			"cyphidcom",
168 	},
169 	.description =			"HID->COM RS232 Adapter",
170 	.id_table =			id_table_cyphidcomrs232,
171 	.num_ports =			1,
172 	.port_probe =			cypress_hidcom_port_probe,
173 	.port_remove =			cypress_port_remove,
174 	.open =				cypress_open,
175 	.close =			cypress_close,
176 	.dtr_rts =			cypress_dtr_rts,
177 	.write =			cypress_write,
178 	.write_room =			cypress_write_room,
179 	.set_termios =			cypress_set_termios,
180 	.tiocmget =			cypress_tiocmget,
181 	.tiocmset =			cypress_tiocmset,
182 	.tiocmiwait =			usb_serial_generic_tiocmiwait,
183 	.chars_in_buffer =		cypress_chars_in_buffer,
184 	.throttle =			cypress_throttle,
185 	.unthrottle =			cypress_unthrottle,
186 	.read_int_callback =		cypress_read_int_callback,
187 	.write_int_callback =		cypress_write_int_callback,
188 };
189 
190 static struct usb_serial_driver cypress_ca42v2_device = {
191 	.driver = {
192 		.owner =		THIS_MODULE,
193 		.name =			"nokiaca42v2",
194 	},
195 	.description =			"Nokia CA-42 V2 Adapter",
196 	.id_table =			id_table_nokiaca42v2,
197 	.num_ports =			1,
198 	.port_probe =			cypress_ca42v2_port_probe,
199 	.port_remove =			cypress_port_remove,
200 	.open =				cypress_open,
201 	.close =			cypress_close,
202 	.dtr_rts =			cypress_dtr_rts,
203 	.write =			cypress_write,
204 	.write_room =			cypress_write_room,
205 	.set_termios =			cypress_set_termios,
206 	.tiocmget =			cypress_tiocmget,
207 	.tiocmset =			cypress_tiocmset,
208 	.tiocmiwait =			usb_serial_generic_tiocmiwait,
209 	.chars_in_buffer =		cypress_chars_in_buffer,
210 	.throttle =			cypress_throttle,
211 	.unthrottle =			cypress_unthrottle,
212 	.read_int_callback =		cypress_read_int_callback,
213 	.write_int_callback =		cypress_write_int_callback,
214 };
215 
216 static struct usb_serial_driver * const serial_drivers[] = {
217 	&cypress_earthmate_device, &cypress_hidcom_device,
218 	&cypress_ca42v2_device, NULL
219 };
220 
221 /*****************************************************************************
222  * Cypress serial helper functions
223  *****************************************************************************/
224 
225 /* FRWD Dongle hidcom needs to skip reset and speed checks */
226 static inline bool is_frwd(struct usb_device *dev)
227 {
228 	return ((le16_to_cpu(dev->descriptor.idVendor) == VENDOR_ID_FRWD) &&
229 		(le16_to_cpu(dev->descriptor.idProduct) == PRODUCT_ID_CYPHIDCOM_FRWD));
230 }
231 
232 static int analyze_baud_rate(struct usb_serial_port *port, speed_t new_rate)
233 {
234 	struct cypress_private *priv;
235 	priv = usb_get_serial_port_data(port);
236 
237 	if (unstable_bauds)
238 		return new_rate;
239 
240 	/* FRWD Dongle uses 115200 bps */
241 	if (is_frwd(port->serial->dev))
242 		return new_rate;
243 
244 	/*
245 	 * The general purpose firmware for the Cypress M8 allows for
246 	 * a maximum speed of 57600bps (I have no idea whether DeLorme
247 	 * chose to use the general purpose firmware or not), if you
248 	 * need to modify this speed setting for your own project
249 	 * please add your own chiptype and modify the code likewise.
250 	 * The Cypress HID->COM device will work successfully up to
251 	 * 115200bps (but the actual throughput is around 3kBps).
252 	 */
253 	if (port->serial->dev->speed == USB_SPEED_LOW) {
254 		/*
255 		 * Mike Isely <isely@pobox.com> 2-Feb-2008: The
256 		 * Cypress app note that describes this mechanism
257 		 * states the the low-speed part can't handle more
258 		 * than 800 bytes/sec, in which case 4800 baud is the
259 		 * safest speed for a part like that.
260 		 */
261 		if (new_rate > 4800) {
262 			dev_dbg(&port->dev,
263 				"%s - failed setting baud rate, device incapable speed %d\n",
264 				__func__, new_rate);
265 			return -1;
266 		}
267 	}
268 	switch (priv->chiptype) {
269 	case CT_EARTHMATE:
270 		if (new_rate <= 600) {
271 			/* 300 and 600 baud rates are supported under
272 			 * the generic firmware, but are not used with
273 			 * NMEA and SiRF protocols */
274 			dev_dbg(&port->dev,
275 				"%s - failed setting baud rate, unsupported speed of %d on Earthmate GPS\n",
276 				__func__, new_rate);
277 			return -1;
278 		}
279 		break;
280 	default:
281 		break;
282 	}
283 	return new_rate;
284 }
285 
286 
287 /* This function can either set or retrieve the current serial line settings */
288 static int cypress_serial_control(struct tty_struct *tty,
289 	struct usb_serial_port *port, speed_t baud_rate, int data_bits,
290 	int stop_bits, int parity_enable, int parity_type, int reset,
291 	int cypress_request_type)
292 {
293 	int new_baudrate = 0, retval = 0, tries = 0;
294 	struct cypress_private *priv;
295 	struct device *dev = &port->dev;
296 	u8 *feature_buffer;
297 	const unsigned int feature_len = 5;
298 	unsigned long flags;
299 
300 	priv = usb_get_serial_port_data(port);
301 
302 	if (!priv->comm_is_ok)
303 		return -ENODEV;
304 
305 	feature_buffer = kcalloc(feature_len, sizeof(u8), GFP_KERNEL);
306 	if (!feature_buffer)
307 		return -ENOMEM;
308 
309 	switch (cypress_request_type) {
310 	case CYPRESS_SET_CONFIG:
311 		/* 0 means 'Hang up' so doesn't change the true bit rate */
312 		new_baudrate = priv->baud_rate;
313 		if (baud_rate && baud_rate != priv->baud_rate) {
314 			dev_dbg(dev, "%s - baud rate is changing\n", __func__);
315 			retval = analyze_baud_rate(port, baud_rate);
316 			if (retval >= 0) {
317 				new_baudrate = retval;
318 				dev_dbg(dev, "%s - New baud rate set to %d\n",
319 					__func__, new_baudrate);
320 			}
321 		}
322 		dev_dbg(dev, "%s - baud rate is being sent as %d\n", __func__,
323 			new_baudrate);
324 
325 		/* fill the feature_buffer with new configuration */
326 		put_unaligned_le32(new_baudrate, feature_buffer);
327 		feature_buffer[4] |= data_bits;   /* assign data bits in 2 bit space ( max 3 ) */
328 		/* 1 bit gap */
329 		feature_buffer[4] |= (stop_bits << 3);   /* assign stop bits in 1 bit space */
330 		feature_buffer[4] |= (parity_enable << 4);   /* assign parity flag in 1 bit space */
331 		feature_buffer[4] |= (parity_type << 5);   /* assign parity type in 1 bit space */
332 		/* 1 bit gap */
333 		feature_buffer[4] |= (reset << 7);   /* assign reset at end of byte, 1 bit space */
334 
335 		dev_dbg(dev, "%s - device is being sent this feature report:\n", __func__);
336 		dev_dbg(dev, "%s - %02X - %02X - %02X - %02X - %02X\n", __func__,
337 			feature_buffer[0], feature_buffer[1],
338 			feature_buffer[2], feature_buffer[3],
339 			feature_buffer[4]);
340 
341 		do {
342 			retval = usb_control_msg(port->serial->dev,
343 					usb_sndctrlpipe(port->serial->dev, 0),
344 					HID_REQ_SET_REPORT,
345 					USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
346 					0x0300, 0, feature_buffer,
347 					feature_len, 500);
348 
349 			if (tries++ >= 3)
350 				break;
351 
352 		} while (retval != feature_len &&
353 			 retval != -ENODEV);
354 
355 		if (retval != feature_len) {
356 			dev_err(dev, "%s - failed sending serial line settings - %d\n",
357 				__func__, retval);
358 			cypress_set_dead(port);
359 		} else {
360 			spin_lock_irqsave(&priv->lock, flags);
361 			priv->baud_rate = new_baudrate;
362 			priv->current_config = feature_buffer[4];
363 			spin_unlock_irqrestore(&priv->lock, flags);
364 			/* If we asked for a speed change encode it */
365 			if (baud_rate)
366 				tty_encode_baud_rate(tty,
367 					new_baudrate, new_baudrate);
368 		}
369 	break;
370 	case CYPRESS_GET_CONFIG:
371 		if (priv->get_cfg_unsafe) {
372 			/* Not implemented for this device,
373 			   and if we try to do it we're likely
374 			   to crash the hardware. */
375 			retval = -ENOTTY;
376 			goto out;
377 		}
378 		dev_dbg(dev, "%s - retrieving serial line settings\n", __func__);
379 		do {
380 			retval = usb_control_msg(port->serial->dev,
381 					usb_rcvctrlpipe(port->serial->dev, 0),
382 					HID_REQ_GET_REPORT,
383 					USB_DIR_IN | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
384 					0x0300, 0, feature_buffer,
385 					feature_len, 500);
386 
387 			if (tries++ >= 3)
388 				break;
389 		} while (retval != feature_len
390 						&& retval != -ENODEV);
391 
392 		if (retval != feature_len) {
393 			dev_err(dev, "%s - failed to retrieve serial line settings - %d\n",
394 				__func__, retval);
395 			cypress_set_dead(port);
396 			goto out;
397 		} else {
398 			spin_lock_irqsave(&priv->lock, flags);
399 			/* store the config in one byte, and later
400 			   use bit masks to check values */
401 			priv->current_config = feature_buffer[4];
402 			priv->baud_rate = get_unaligned_le32(feature_buffer);
403 			spin_unlock_irqrestore(&priv->lock, flags);
404 		}
405 	}
406 	spin_lock_irqsave(&priv->lock, flags);
407 	++priv->cmd_count;
408 	spin_unlock_irqrestore(&priv->lock, flags);
409 out:
410 	kfree(feature_buffer);
411 	return retval;
412 } /* cypress_serial_control */
413 
414 
415 static void cypress_set_dead(struct usb_serial_port *port)
416 {
417 	struct cypress_private *priv = usb_get_serial_port_data(port);
418 	unsigned long flags;
419 
420 	spin_lock_irqsave(&priv->lock, flags);
421 	if (!priv->comm_is_ok) {
422 		spin_unlock_irqrestore(&priv->lock, flags);
423 		return;
424 	}
425 	priv->comm_is_ok = 0;
426 	spin_unlock_irqrestore(&priv->lock, flags);
427 
428 	dev_err(&port->dev, "cypress_m8 suspending failing port %d - "
429 		"interval might be too short\n", port->port_number);
430 }
431 
432 
433 /*****************************************************************************
434  * Cypress serial driver functions
435  *****************************************************************************/
436 
437 
438 static int cypress_generic_port_probe(struct usb_serial_port *port)
439 {
440 	struct usb_serial *serial = port->serial;
441 	struct cypress_private *priv;
442 
443 	if (!port->interrupt_out_urb || !port->interrupt_in_urb) {
444 		dev_err(&port->dev, "required endpoint is missing\n");
445 		return -ENODEV;
446 	}
447 
448 	priv = kzalloc(sizeof(struct cypress_private), GFP_KERNEL);
449 	if (!priv)
450 		return -ENOMEM;
451 
452 	priv->comm_is_ok = !0;
453 	spin_lock_init(&priv->lock);
454 	if (kfifo_alloc(&priv->write_fifo, CYPRESS_BUF_SIZE, GFP_KERNEL)) {
455 		kfree(priv);
456 		return -ENOMEM;
457 	}
458 
459 	/* Skip reset for FRWD device. It is a workaound:
460 	   device hangs if it receives SET_CONFIGURE in Configured
461 	   state. */
462 	if (!is_frwd(serial->dev))
463 		usb_reset_configuration(serial->dev);
464 
465 	priv->cmd_ctrl = 0;
466 	priv->line_control = 0;
467 	priv->rx_flags = 0;
468 	/* Default packet format setting is determined by packet size.
469 	   Anything with a size larger then 9 must have a separate
470 	   count field since the 3 bit count field is otherwise too
471 	   small.  Otherwise we can use the slightly more compact
472 	   format.  This is in accordance with the cypress_m8 serial
473 	   converter app note. */
474 	if (port->interrupt_out_size > 9)
475 		priv->pkt_fmt = packet_format_1;
476 	else
477 		priv->pkt_fmt = packet_format_2;
478 
479 	if (interval > 0) {
480 		priv->write_urb_interval = interval;
481 		priv->read_urb_interval = interval;
482 		dev_dbg(&port->dev, "%s - read & write intervals forced to %d\n",
483 			__func__, interval);
484 	} else {
485 		priv->write_urb_interval = port->interrupt_out_urb->interval;
486 		priv->read_urb_interval = port->interrupt_in_urb->interval;
487 		dev_dbg(&port->dev, "%s - intervals: read=%d write=%d\n",
488 			__func__, priv->read_urb_interval,
489 			priv->write_urb_interval);
490 	}
491 	usb_set_serial_port_data(port, priv);
492 
493 	port->port.drain_delay = 256;
494 
495 	return 0;
496 }
497 
498 
499 static int cypress_earthmate_port_probe(struct usb_serial_port *port)
500 {
501 	struct usb_serial *serial = port->serial;
502 	struct cypress_private *priv;
503 	int ret;
504 
505 	ret = cypress_generic_port_probe(port);
506 	if (ret) {
507 		dev_dbg(&port->dev, "%s - Failed setting up port\n", __func__);
508 		return ret;
509 	}
510 
511 	priv = usb_get_serial_port_data(port);
512 	priv->chiptype = CT_EARTHMATE;
513 	/* All Earthmate devices use the separated-count packet
514 	   format!  Idiotic. */
515 	priv->pkt_fmt = packet_format_1;
516 	if (serial->dev->descriptor.idProduct !=
517 				cpu_to_le16(PRODUCT_ID_EARTHMATEUSB)) {
518 		/* The old original USB Earthmate seemed able to
519 		   handle GET_CONFIG requests; everything they've
520 		   produced since that time crashes if this command is
521 		   attempted :-( */
522 		dev_dbg(&port->dev,
523 			"%s - Marking this device as unsafe for GET_CONFIG commands\n",
524 			__func__);
525 		priv->get_cfg_unsafe = !0;
526 	}
527 
528 	return 0;
529 }
530 
531 static int cypress_hidcom_port_probe(struct usb_serial_port *port)
532 {
533 	struct cypress_private *priv;
534 	int ret;
535 
536 	ret = cypress_generic_port_probe(port);
537 	if (ret) {
538 		dev_dbg(&port->dev, "%s - Failed setting up port\n", __func__);
539 		return ret;
540 	}
541 
542 	priv = usb_get_serial_port_data(port);
543 	priv->chiptype = CT_CYPHIDCOM;
544 
545 	return 0;
546 }
547 
548 static int cypress_ca42v2_port_probe(struct usb_serial_port *port)
549 {
550 	struct cypress_private *priv;
551 	int ret;
552 
553 	ret = cypress_generic_port_probe(port);
554 	if (ret) {
555 		dev_dbg(&port->dev, "%s - Failed setting up port\n", __func__);
556 		return ret;
557 	}
558 
559 	priv = usb_get_serial_port_data(port);
560 	priv->chiptype = CT_CA42V2;
561 
562 	return 0;
563 }
564 
565 static int cypress_port_remove(struct usb_serial_port *port)
566 {
567 	struct cypress_private *priv;
568 
569 	priv = usb_get_serial_port_data(port);
570 
571 	kfifo_free(&priv->write_fifo);
572 	kfree(priv);
573 
574 	return 0;
575 }
576 
577 static int cypress_open(struct tty_struct *tty, struct usb_serial_port *port)
578 {
579 	struct cypress_private *priv = usb_get_serial_port_data(port);
580 	struct usb_serial *serial = port->serial;
581 	unsigned long flags;
582 	int result = 0;
583 
584 	if (!priv->comm_is_ok)
585 		return -EIO;
586 
587 	/* clear halts before open */
588 	usb_clear_halt(serial->dev, 0x81);
589 	usb_clear_halt(serial->dev, 0x02);
590 
591 	spin_lock_irqsave(&priv->lock, flags);
592 	/* reset read/write statistics */
593 	priv->bytes_in = 0;
594 	priv->bytes_out = 0;
595 	priv->cmd_count = 0;
596 	priv->rx_flags = 0;
597 	spin_unlock_irqrestore(&priv->lock, flags);
598 
599 	/* Set termios */
600 	cypress_send(port);
601 
602 	if (tty)
603 		cypress_set_termios(tty, port, NULL);
604 
605 	/* setup the port and start reading from the device */
606 	usb_fill_int_urb(port->interrupt_in_urb, serial->dev,
607 		usb_rcvintpipe(serial->dev, port->interrupt_in_endpointAddress),
608 		port->interrupt_in_urb->transfer_buffer,
609 		port->interrupt_in_urb->transfer_buffer_length,
610 		cypress_read_int_callback, port, priv->read_urb_interval);
611 	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
612 
613 	if (result) {
614 		dev_err(&port->dev,
615 			"%s - failed submitting read urb, error %d\n",
616 							__func__, result);
617 		cypress_set_dead(port);
618 	}
619 
620 	return result;
621 } /* cypress_open */
622 
623 static void cypress_dtr_rts(struct usb_serial_port *port, int on)
624 {
625 	struct cypress_private *priv = usb_get_serial_port_data(port);
626 	/* drop dtr and rts */
627 	spin_lock_irq(&priv->lock);
628 	if (on == 0)
629 		priv->line_control = 0;
630 	else
631 		priv->line_control = CONTROL_DTR | CONTROL_RTS;
632 	priv->cmd_ctrl = 1;
633 	spin_unlock_irq(&priv->lock);
634 	cypress_write(NULL, port, NULL, 0);
635 }
636 
637 static void cypress_close(struct usb_serial_port *port)
638 {
639 	struct cypress_private *priv = usb_get_serial_port_data(port);
640 	unsigned long flags;
641 
642 	spin_lock_irqsave(&priv->lock, flags);
643 	kfifo_reset_out(&priv->write_fifo);
644 	spin_unlock_irqrestore(&priv->lock, flags);
645 
646 	dev_dbg(&port->dev, "%s - stopping urbs\n", __func__);
647 	usb_kill_urb(port->interrupt_in_urb);
648 	usb_kill_urb(port->interrupt_out_urb);
649 
650 	if (stats)
651 		dev_info(&port->dev, "Statistics: %d Bytes In | %d Bytes Out | %d Commands Issued\n",
652 			priv->bytes_in, priv->bytes_out, priv->cmd_count);
653 } /* cypress_close */
654 
655 
656 static int cypress_write(struct tty_struct *tty, struct usb_serial_port *port,
657 					const unsigned char *buf, int count)
658 {
659 	struct cypress_private *priv = usb_get_serial_port_data(port);
660 
661 	dev_dbg(&port->dev, "%s - %d bytes\n", __func__, count);
662 
663 	/* line control commands, which need to be executed immediately,
664 	   are not put into the buffer for obvious reasons.
665 	 */
666 	if (priv->cmd_ctrl) {
667 		count = 0;
668 		goto finish;
669 	}
670 
671 	if (!count)
672 		return count;
673 
674 	count = kfifo_in_locked(&priv->write_fifo, buf, count, &priv->lock);
675 
676 finish:
677 	cypress_send(port);
678 
679 	return count;
680 } /* cypress_write */
681 
682 
683 static void cypress_send(struct usb_serial_port *port)
684 {
685 	int count = 0, result, offset, actual_size;
686 	struct cypress_private *priv = usb_get_serial_port_data(port);
687 	struct device *dev = &port->dev;
688 	unsigned long flags;
689 
690 	if (!priv->comm_is_ok)
691 		return;
692 
693 	dev_dbg(dev, "%s - interrupt out size is %d\n", __func__,
694 		port->interrupt_out_size);
695 
696 	spin_lock_irqsave(&priv->lock, flags);
697 	if (priv->write_urb_in_use) {
698 		dev_dbg(dev, "%s - can't write, urb in use\n", __func__);
699 		spin_unlock_irqrestore(&priv->lock, flags);
700 		return;
701 	}
702 	spin_unlock_irqrestore(&priv->lock, flags);
703 
704 	/* clear buffer */
705 	memset(port->interrupt_out_urb->transfer_buffer, 0,
706 						port->interrupt_out_size);
707 
708 	spin_lock_irqsave(&priv->lock, flags);
709 	switch (priv->pkt_fmt) {
710 	default:
711 	case packet_format_1:
712 		/* this is for the CY7C64013... */
713 		offset = 2;
714 		port->interrupt_out_buffer[0] = priv->line_control;
715 		break;
716 	case packet_format_2:
717 		/* this is for the CY7C63743... */
718 		offset = 1;
719 		port->interrupt_out_buffer[0] = priv->line_control;
720 		break;
721 	}
722 
723 	if (priv->line_control & CONTROL_RESET)
724 		priv->line_control &= ~CONTROL_RESET;
725 
726 	if (priv->cmd_ctrl) {
727 		priv->cmd_count++;
728 		dev_dbg(dev, "%s - line control command being issued\n", __func__);
729 		spin_unlock_irqrestore(&priv->lock, flags);
730 		goto send;
731 	} else
732 		spin_unlock_irqrestore(&priv->lock, flags);
733 
734 	count = kfifo_out_locked(&priv->write_fifo,
735 					&port->interrupt_out_buffer[offset],
736 					port->interrupt_out_size - offset,
737 					&priv->lock);
738 	if (count == 0)
739 		return;
740 
741 	switch (priv->pkt_fmt) {
742 	default:
743 	case packet_format_1:
744 		port->interrupt_out_buffer[1] = count;
745 		break;
746 	case packet_format_2:
747 		port->interrupt_out_buffer[0] |= count;
748 	}
749 
750 	dev_dbg(dev, "%s - count is %d\n", __func__, count);
751 
752 send:
753 	spin_lock_irqsave(&priv->lock, flags);
754 	priv->write_urb_in_use = 1;
755 	spin_unlock_irqrestore(&priv->lock, flags);
756 
757 	if (priv->cmd_ctrl)
758 		actual_size = 1;
759 	else
760 		actual_size = count +
761 			      (priv->pkt_fmt == packet_format_1 ? 2 : 1);
762 
763 	usb_serial_debug_data(dev, __func__, port->interrupt_out_size,
764 			      port->interrupt_out_urb->transfer_buffer);
765 
766 	usb_fill_int_urb(port->interrupt_out_urb, port->serial->dev,
767 		usb_sndintpipe(port->serial->dev, port->interrupt_out_endpointAddress),
768 		port->interrupt_out_buffer, actual_size,
769 		cypress_write_int_callback, port, priv->write_urb_interval);
770 	result = usb_submit_urb(port->interrupt_out_urb, GFP_ATOMIC);
771 	if (result) {
772 		dev_err_console(port,
773 				"%s - failed submitting write urb, error %d\n",
774 							__func__, result);
775 		priv->write_urb_in_use = 0;
776 		cypress_set_dead(port);
777 	}
778 
779 	spin_lock_irqsave(&priv->lock, flags);
780 	if (priv->cmd_ctrl)
781 		priv->cmd_ctrl = 0;
782 
783 	/* do not count the line control and size bytes */
784 	priv->bytes_out += count;
785 	spin_unlock_irqrestore(&priv->lock, flags);
786 
787 	usb_serial_port_softint(port);
788 } /* cypress_send */
789 
790 
791 /* returns how much space is available in the soft buffer */
792 static int cypress_write_room(struct tty_struct *tty)
793 {
794 	struct usb_serial_port *port = tty->driver_data;
795 	struct cypress_private *priv = usb_get_serial_port_data(port);
796 	int room = 0;
797 	unsigned long flags;
798 
799 	spin_lock_irqsave(&priv->lock, flags);
800 	room = kfifo_avail(&priv->write_fifo);
801 	spin_unlock_irqrestore(&priv->lock, flags);
802 
803 	dev_dbg(&port->dev, "%s - returns %d\n", __func__, room);
804 	return room;
805 }
806 
807 
808 static int cypress_tiocmget(struct tty_struct *tty)
809 {
810 	struct usb_serial_port *port = tty->driver_data;
811 	struct cypress_private *priv = usb_get_serial_port_data(port);
812 	__u8 status, control;
813 	unsigned int result = 0;
814 	unsigned long flags;
815 
816 	spin_lock_irqsave(&priv->lock, flags);
817 	control = priv->line_control;
818 	status = priv->current_status;
819 	spin_unlock_irqrestore(&priv->lock, flags);
820 
821 	result = ((control & CONTROL_DTR)        ? TIOCM_DTR : 0)
822 		| ((control & CONTROL_RTS)       ? TIOCM_RTS : 0)
823 		| ((status & UART_CTS)        ? TIOCM_CTS : 0)
824 		| ((status & UART_DSR)        ? TIOCM_DSR : 0)
825 		| ((status & UART_RI)         ? TIOCM_RI  : 0)
826 		| ((status & UART_CD)         ? TIOCM_CD  : 0);
827 
828 	dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
829 
830 	return result;
831 }
832 
833 
834 static int cypress_tiocmset(struct tty_struct *tty,
835 			       unsigned int set, unsigned int clear)
836 {
837 	struct usb_serial_port *port = tty->driver_data;
838 	struct cypress_private *priv = usb_get_serial_port_data(port);
839 	unsigned long flags;
840 
841 	spin_lock_irqsave(&priv->lock, flags);
842 	if (set & TIOCM_RTS)
843 		priv->line_control |= CONTROL_RTS;
844 	if (set & TIOCM_DTR)
845 		priv->line_control |= CONTROL_DTR;
846 	if (clear & TIOCM_RTS)
847 		priv->line_control &= ~CONTROL_RTS;
848 	if (clear & TIOCM_DTR)
849 		priv->line_control &= ~CONTROL_DTR;
850 	priv->cmd_ctrl = 1;
851 	spin_unlock_irqrestore(&priv->lock, flags);
852 
853 	return cypress_write(tty, port, NULL, 0);
854 }
855 
856 static void cypress_earthmate_init_termios(struct tty_struct *tty)
857 {
858 	tty_encode_baud_rate(tty, 4800, 4800);
859 }
860 
861 static void cypress_set_termios(struct tty_struct *tty,
862 	struct usb_serial_port *port, struct ktermios *old_termios)
863 {
864 	struct cypress_private *priv = usb_get_serial_port_data(port);
865 	struct device *dev = &port->dev;
866 	int data_bits, stop_bits, parity_type, parity_enable;
867 	unsigned int cflag;
868 	unsigned long flags;
869 	__u8 oldlines;
870 	int linechange = 0;
871 
872 	/* Unsupported features need clearing */
873 	tty->termios.c_cflag &= ~(CMSPAR|CRTSCTS);
874 
875 	cflag = tty->termios.c_cflag;
876 
877 	/* set number of data bits, parity, stop bits */
878 	/* when parity is disabled the parity type bit is ignored */
879 
880 	/* 1 means 2 stop bits, 0 means 1 stop bit */
881 	stop_bits = cflag & CSTOPB ? 1 : 0;
882 
883 	if (cflag & PARENB) {
884 		parity_enable = 1;
885 		/* 1 means odd parity, 0 means even parity */
886 		parity_type = cflag & PARODD ? 1 : 0;
887 	} else
888 		parity_enable = parity_type = 0;
889 
890 	switch (cflag & CSIZE) {
891 	case CS5:
892 		data_bits = 0;
893 		break;
894 	case CS6:
895 		data_bits = 1;
896 		break;
897 	case CS7:
898 		data_bits = 2;
899 		break;
900 	case CS8:
901 		data_bits = 3;
902 		break;
903 	default:
904 		dev_err(dev, "%s - CSIZE was set, but not CS5-CS8\n", __func__);
905 		data_bits = 3;
906 	}
907 	spin_lock_irqsave(&priv->lock, flags);
908 	oldlines = priv->line_control;
909 	if ((cflag & CBAUD) == B0) {
910 		/* drop dtr and rts */
911 		dev_dbg(dev, "%s - dropping the lines, baud rate 0bps\n", __func__);
912 		priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
913 	} else
914 		priv->line_control = (CONTROL_DTR | CONTROL_RTS);
915 	spin_unlock_irqrestore(&priv->lock, flags);
916 
917 	dev_dbg(dev, "%s - sending %d stop_bits, %d parity_enable, %d parity_type, %d data_bits (+5)\n",
918 		__func__, stop_bits, parity_enable, parity_type, data_bits);
919 
920 	cypress_serial_control(tty, port, tty_get_baud_rate(tty),
921 			data_bits, stop_bits,
922 			parity_enable, parity_type,
923 			0, CYPRESS_SET_CONFIG);
924 
925 	/* we perform a CYPRESS_GET_CONFIG so that the current settings are
926 	 * filled into the private structure this should confirm that all is
927 	 * working if it returns what we just set */
928 	cypress_serial_control(tty, port, 0, 0, 0, 0, 0, 0, CYPRESS_GET_CONFIG);
929 
930 	/* Here we can define custom tty settings for devices; the main tty
931 	 * termios flag base comes from empeg.c */
932 
933 	spin_lock_irqsave(&priv->lock, flags);
934 	if (priv->chiptype == CT_EARTHMATE && priv->baud_rate == 4800) {
935 		dev_dbg(dev, "Using custom termios settings for a baud rate of 4800bps.\n");
936 		/* define custom termios settings for NMEA protocol */
937 
938 		tty->termios.c_iflag /* input modes - */
939 			&= ~(IGNBRK  /* disable ignore break */
940 			| BRKINT     /* disable break causes interrupt */
941 			| PARMRK     /* disable mark parity errors */
942 			| ISTRIP     /* disable clear high bit of input char */
943 			| INLCR      /* disable translate NL to CR */
944 			| IGNCR      /* disable ignore CR */
945 			| ICRNL      /* disable translate CR to NL */
946 			| IXON);     /* disable enable XON/XOFF flow control */
947 
948 		tty->termios.c_oflag /* output modes */
949 			&= ~OPOST;    /* disable postprocess output char */
950 
951 		tty->termios.c_lflag /* line discipline modes */
952 			&= ~(ECHO     /* disable echo input characters */
953 			| ECHONL      /* disable echo new line */
954 			| ICANON      /* disable erase, kill, werase, and rprnt
955 					 special characters */
956 			| ISIG        /* disable interrupt, quit, and suspend
957 					 special characters */
958 			| IEXTEN);    /* disable non-POSIX special characters */
959 	} /* CT_CYPHIDCOM: Application should handle this for device */
960 
961 	linechange = (priv->line_control != oldlines);
962 	spin_unlock_irqrestore(&priv->lock, flags);
963 
964 	/* if necessary, set lines */
965 	if (linechange) {
966 		priv->cmd_ctrl = 1;
967 		cypress_write(tty, port, NULL, 0);
968 	}
969 } /* cypress_set_termios */
970 
971 
972 /* returns amount of data still left in soft buffer */
973 static int cypress_chars_in_buffer(struct tty_struct *tty)
974 {
975 	struct usb_serial_port *port = tty->driver_data;
976 	struct cypress_private *priv = usb_get_serial_port_data(port);
977 	int chars = 0;
978 	unsigned long flags;
979 
980 	spin_lock_irqsave(&priv->lock, flags);
981 	chars = kfifo_len(&priv->write_fifo);
982 	spin_unlock_irqrestore(&priv->lock, flags);
983 
984 	dev_dbg(&port->dev, "%s - returns %d\n", __func__, chars);
985 	return chars;
986 }
987 
988 
989 static void cypress_throttle(struct tty_struct *tty)
990 {
991 	struct usb_serial_port *port = tty->driver_data;
992 	struct cypress_private *priv = usb_get_serial_port_data(port);
993 
994 	spin_lock_irq(&priv->lock);
995 	priv->rx_flags = THROTTLED;
996 	spin_unlock_irq(&priv->lock);
997 }
998 
999 
1000 static void cypress_unthrottle(struct tty_struct *tty)
1001 {
1002 	struct usb_serial_port *port = tty->driver_data;
1003 	struct cypress_private *priv = usb_get_serial_port_data(port);
1004 	int actually_throttled, result;
1005 
1006 	spin_lock_irq(&priv->lock);
1007 	actually_throttled = priv->rx_flags & ACTUALLY_THROTTLED;
1008 	priv->rx_flags = 0;
1009 	spin_unlock_irq(&priv->lock);
1010 
1011 	if (!priv->comm_is_ok)
1012 		return;
1013 
1014 	if (actually_throttled) {
1015 		result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
1016 		if (result) {
1017 			dev_err(&port->dev, "%s - failed submitting read urb, "
1018 					"error %d\n", __func__, result);
1019 			cypress_set_dead(port);
1020 		}
1021 	}
1022 }
1023 
1024 
1025 static void cypress_read_int_callback(struct urb *urb)
1026 {
1027 	struct usb_serial_port *port = urb->context;
1028 	struct cypress_private *priv = usb_get_serial_port_data(port);
1029 	struct device *dev = &urb->dev->dev;
1030 	struct tty_struct *tty;
1031 	unsigned char *data = urb->transfer_buffer;
1032 	unsigned long flags;
1033 	char tty_flag = TTY_NORMAL;
1034 	int bytes = 0;
1035 	int result;
1036 	int i = 0;
1037 	int status = urb->status;
1038 
1039 	switch (status) {
1040 	case 0: /* success */
1041 		break;
1042 	case -ECONNRESET:
1043 	case -ENOENT:
1044 	case -ESHUTDOWN:
1045 		/* precursor to disconnect so just go away */
1046 		return;
1047 	case -EPIPE:
1048 		/* Can't call usb_clear_halt while in_interrupt */
1049 		/* FALLS THROUGH */
1050 	default:
1051 		/* something ugly is going on... */
1052 		dev_err(dev, "%s - unexpected nonzero read status received: %d\n",
1053 			__func__, status);
1054 		cypress_set_dead(port);
1055 		return;
1056 	}
1057 
1058 	spin_lock_irqsave(&priv->lock, flags);
1059 	if (priv->rx_flags & THROTTLED) {
1060 		dev_dbg(dev, "%s - now throttling\n", __func__);
1061 		priv->rx_flags |= ACTUALLY_THROTTLED;
1062 		spin_unlock_irqrestore(&priv->lock, flags);
1063 		return;
1064 	}
1065 	spin_unlock_irqrestore(&priv->lock, flags);
1066 
1067 	tty = tty_port_tty_get(&port->port);
1068 	if (!tty) {
1069 		dev_dbg(dev, "%s - bad tty pointer - exiting\n", __func__);
1070 		return;
1071 	}
1072 
1073 	spin_lock_irqsave(&priv->lock, flags);
1074 	result = urb->actual_length;
1075 	switch (priv->pkt_fmt) {
1076 	default:
1077 	case packet_format_1:
1078 		/* This is for the CY7C64013... */
1079 		priv->current_status = data[0] & 0xF8;
1080 		bytes = data[1] + 2;
1081 		i = 2;
1082 		break;
1083 	case packet_format_2:
1084 		/* This is for the CY7C63743... */
1085 		priv->current_status = data[0] & 0xF8;
1086 		bytes = (data[0] & 0x07) + 1;
1087 		i = 1;
1088 		break;
1089 	}
1090 	spin_unlock_irqrestore(&priv->lock, flags);
1091 	if (result < bytes) {
1092 		dev_dbg(dev,
1093 			"%s - wrong packet size - received %d bytes but packet said %d bytes\n",
1094 			__func__, result, bytes);
1095 		goto continue_read;
1096 	}
1097 
1098 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
1099 
1100 	spin_lock_irqsave(&priv->lock, flags);
1101 	/* check to see if status has changed */
1102 	if (priv->current_status != priv->prev_status) {
1103 		u8 delta = priv->current_status ^ priv->prev_status;
1104 
1105 		if (delta & UART_MSR_MASK) {
1106 			if (delta & UART_CTS)
1107 				port->icount.cts++;
1108 			if (delta & UART_DSR)
1109 				port->icount.dsr++;
1110 			if (delta & UART_RI)
1111 				port->icount.rng++;
1112 			if (delta & UART_CD)
1113 				port->icount.dcd++;
1114 
1115 			wake_up_interruptible(&port->port.delta_msr_wait);
1116 		}
1117 
1118 		priv->prev_status = priv->current_status;
1119 	}
1120 	spin_unlock_irqrestore(&priv->lock, flags);
1121 
1122 	/* hangup, as defined in acm.c... this might be a bad place for it
1123 	 * though */
1124 	if (tty && !C_CLOCAL(tty) && !(priv->current_status & UART_CD)) {
1125 		dev_dbg(dev, "%s - calling hangup\n", __func__);
1126 		tty_hangup(tty);
1127 		goto continue_read;
1128 	}
1129 
1130 	/* There is one error bit... I'm assuming it is a parity error
1131 	 * indicator as the generic firmware will set this bit to 1 if a
1132 	 * parity error occurs.
1133 	 * I can not find reference to any other error events. */
1134 	spin_lock_irqsave(&priv->lock, flags);
1135 	if (priv->current_status & CYP_ERROR) {
1136 		spin_unlock_irqrestore(&priv->lock, flags);
1137 		tty_flag = TTY_PARITY;
1138 		dev_dbg(dev, "%s - Parity Error detected\n", __func__);
1139 	} else
1140 		spin_unlock_irqrestore(&priv->lock, flags);
1141 
1142 	/* process read if there is data other than line status */
1143 	if (bytes > i) {
1144 		tty_insert_flip_string_fixed_flag(&port->port, data + i,
1145 				tty_flag, bytes - i);
1146 		tty_flip_buffer_push(&port->port);
1147 	}
1148 
1149 	spin_lock_irqsave(&priv->lock, flags);
1150 	/* control and status byte(s) are also counted */
1151 	priv->bytes_in += bytes;
1152 	spin_unlock_irqrestore(&priv->lock, flags);
1153 
1154 continue_read:
1155 	tty_kref_put(tty);
1156 
1157 	/* Continue trying to always read */
1158 
1159 	if (priv->comm_is_ok) {
1160 		usb_fill_int_urb(port->interrupt_in_urb, port->serial->dev,
1161 				usb_rcvintpipe(port->serial->dev,
1162 					port->interrupt_in_endpointAddress),
1163 				port->interrupt_in_urb->transfer_buffer,
1164 				port->interrupt_in_urb->transfer_buffer_length,
1165 				cypress_read_int_callback, port,
1166 				priv->read_urb_interval);
1167 		result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
1168 		if (result && result != -EPERM) {
1169 			dev_err(dev, "%s - failed resubmitting read urb, error %d\n",
1170 				__func__, result);
1171 			cypress_set_dead(port);
1172 		}
1173 	}
1174 } /* cypress_read_int_callback */
1175 
1176 
1177 static void cypress_write_int_callback(struct urb *urb)
1178 {
1179 	struct usb_serial_port *port = urb->context;
1180 	struct cypress_private *priv = usb_get_serial_port_data(port);
1181 	struct device *dev = &urb->dev->dev;
1182 	int status = urb->status;
1183 
1184 	switch (status) {
1185 	case 0:
1186 		/* success */
1187 		break;
1188 	case -ECONNRESET:
1189 	case -ENOENT:
1190 	case -ESHUTDOWN:
1191 		/* this urb is terminated, clean up */
1192 		dev_dbg(dev, "%s - urb shutting down with status: %d\n",
1193 			__func__, status);
1194 		priv->write_urb_in_use = 0;
1195 		return;
1196 	case -EPIPE:
1197 		/* Cannot call usb_clear_halt while in_interrupt */
1198 		/* FALLTHROUGH */
1199 	default:
1200 		dev_err(dev, "%s - unexpected nonzero write status received: %d\n",
1201 			__func__, status);
1202 		cypress_set_dead(port);
1203 		break;
1204 	}
1205 	priv->write_urb_in_use = 0;
1206 
1207 	/* send any buffered data */
1208 	cypress_send(port);
1209 }
1210 
1211 module_usb_serial_driver(serial_drivers, id_table_combined);
1212 
1213 MODULE_AUTHOR(DRIVER_AUTHOR);
1214 MODULE_DESCRIPTION(DRIVER_DESC);
1215 MODULE_LICENSE("GPL");
1216 
1217 module_param(stats, bool, S_IRUGO | S_IWUSR);
1218 MODULE_PARM_DESC(stats, "Enable statistics or not");
1219 module_param(interval, int, S_IRUGO | S_IWUSR);
1220 MODULE_PARM_DESC(interval, "Overrides interrupt interval");
1221 module_param(unstable_bauds, bool, S_IRUGO | S_IWUSR);
1222 MODULE_PARM_DESC(unstable_bauds, "Allow unstable baud rates");
1223