xref: /linux/drivers/usb/serial/cypress_m8.c (revision 4b132aacb0768ac1e652cf517097ea6f237214b9)
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_SAI, PRODUCT_ID_CYPHIDCOM) },
63 	{ USB_DEVICE(VENDOR_ID_POWERCOM, PRODUCT_ID_UPS) },
64 	{ USB_DEVICE(VENDOR_ID_FRWD, PRODUCT_ID_CYPHIDCOM_FRWD) },
65 	{ }						/* Terminating entry */
66 };
67 
68 static const struct usb_device_id id_table_nokiaca42v2[] = {
69 	{ USB_DEVICE(VENDOR_ID_DAZZLE, PRODUCT_ID_CA42) },
70 	{ }						/* Terminating entry */
71 };
72 
73 static const struct usb_device_id id_table_combined[] = {
74 	{ USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB) },
75 	{ USB_DEVICE(VENDOR_ID_DELORME, PRODUCT_ID_EARTHMATEUSB_LT20) },
76 	{ USB_DEVICE(VENDOR_ID_CYPRESS, PRODUCT_ID_CYPHIDCOM) },
77 	{ USB_DEVICE(VENDOR_ID_SAI, PRODUCT_ID_CYPHIDCOM) },
78 	{ USB_DEVICE(VENDOR_ID_POWERCOM, PRODUCT_ID_UPS) },
79 	{ USB_DEVICE(VENDOR_ID_FRWD, PRODUCT_ID_CYPHIDCOM_FRWD) },
80 	{ USB_DEVICE(VENDOR_ID_DAZZLE, PRODUCT_ID_CA42) },
81 	{ }						/* Terminating entry */
82 };
83 
84 MODULE_DEVICE_TABLE(usb, id_table_combined);
85 
86 enum packet_format {
87 	packet_format_1,  /* b0:status, b1:payload count */
88 	packet_format_2   /* b0[7:3]:status, b0[2:0]:payload count */
89 };
90 
91 struct cypress_private {
92 	spinlock_t lock;		   /* private lock */
93 	int chiptype;			   /* identifier of device, for quirks/etc */
94 	int bytes_in;			   /* used for statistics */
95 	int bytes_out;			   /* used for statistics */
96 	int cmd_count;			   /* used for statistics */
97 	int cmd_ctrl;			   /* always set this to 1 before issuing a command */
98 	struct kfifo write_fifo;	   /* write fifo */
99 	int write_urb_in_use;		   /* write urb in use indicator */
100 	int write_urb_interval;            /* interval to use for write urb */
101 	int read_urb_interval;             /* interval to use for read urb */
102 	int comm_is_ok;                    /* true if communication is (still) ok */
103 	__u8 line_control;	   	   /* holds dtr / rts value */
104 	__u8 current_status;	   	   /* received from last read - info on dsr,cts,cd,ri,etc */
105 	__u8 current_config;	   	   /* stores the current configuration byte */
106 	__u8 rx_flags;			   /* throttling - used from whiteheat/ftdi_sio */
107 	enum packet_format pkt_fmt;	   /* format to use for packet send / receive */
108 	int get_cfg_unsafe;		   /* If true, the CYPRESS_GET_CONFIG is unsafe */
109 	int baud_rate;			   /* stores current baud rate in
110 					      integer form */
111 	char prev_status;		   /* used for TIOCMIWAIT */
112 };
113 
114 /* function prototypes for the Cypress USB to serial device */
115 static int  cypress_earthmate_port_probe(struct usb_serial_port *port);
116 static int  cypress_hidcom_port_probe(struct usb_serial_port *port);
117 static int  cypress_ca42v2_port_probe(struct usb_serial_port *port);
118 static void cypress_port_remove(struct usb_serial_port *port);
119 static int  cypress_open(struct tty_struct *tty, struct usb_serial_port *port);
120 static void cypress_close(struct usb_serial_port *port);
121 static void cypress_dtr_rts(struct usb_serial_port *port, int on);
122 static int  cypress_write(struct tty_struct *tty, struct usb_serial_port *port,
123 			const unsigned char *buf, int count);
124 static void cypress_send(struct usb_serial_port *port);
125 static unsigned int cypress_write_room(struct tty_struct *tty);
126 static void cypress_earthmate_init_termios(struct tty_struct *tty);
127 static void cypress_set_termios(struct tty_struct *tty,
128 				struct usb_serial_port *port,
129 				const struct ktermios *old_termios);
130 static int  cypress_tiocmget(struct tty_struct *tty);
131 static int  cypress_tiocmset(struct tty_struct *tty,
132 			unsigned int set, unsigned int clear);
133 static unsigned int cypress_chars_in_buffer(struct tty_struct *tty);
134 static void cypress_throttle(struct tty_struct *tty);
135 static void cypress_unthrottle(struct tty_struct *tty);
136 static void cypress_set_dead(struct usb_serial_port *port);
137 static void cypress_read_int_callback(struct urb *urb);
138 static void cypress_write_int_callback(struct urb *urb);
139 
140 static struct usb_serial_driver cypress_earthmate_device = {
141 	.driver = {
142 		.owner =		THIS_MODULE,
143 		.name =			"earthmate",
144 	},
145 	.description =			"DeLorme Earthmate USB",
146 	.id_table =			id_table_earthmate,
147 	.num_ports =			1,
148 	.port_probe =			cypress_earthmate_port_probe,
149 	.port_remove =			cypress_port_remove,
150 	.open =				cypress_open,
151 	.close =			cypress_close,
152 	.dtr_rts =			cypress_dtr_rts,
153 	.write =			cypress_write,
154 	.write_room =			cypress_write_room,
155 	.init_termios =			cypress_earthmate_init_termios,
156 	.set_termios =			cypress_set_termios,
157 	.tiocmget =			cypress_tiocmget,
158 	.tiocmset =			cypress_tiocmset,
159 	.tiocmiwait =			usb_serial_generic_tiocmiwait,
160 	.chars_in_buffer =		cypress_chars_in_buffer,
161 	.throttle =		 	cypress_throttle,
162 	.unthrottle =			cypress_unthrottle,
163 	.read_int_callback =		cypress_read_int_callback,
164 	.write_int_callback =		cypress_write_int_callback,
165 };
166 
167 static struct usb_serial_driver cypress_hidcom_device = {
168 	.driver = {
169 		.owner =		THIS_MODULE,
170 		.name =			"cyphidcom",
171 	},
172 	.description =			"HID->COM RS232 Adapter",
173 	.id_table =			id_table_cyphidcomrs232,
174 	.num_ports =			1,
175 	.port_probe =			cypress_hidcom_port_probe,
176 	.port_remove =			cypress_port_remove,
177 	.open =				cypress_open,
178 	.close =			cypress_close,
179 	.dtr_rts =			cypress_dtr_rts,
180 	.write =			cypress_write,
181 	.write_room =			cypress_write_room,
182 	.set_termios =			cypress_set_termios,
183 	.tiocmget =			cypress_tiocmget,
184 	.tiocmset =			cypress_tiocmset,
185 	.tiocmiwait =			usb_serial_generic_tiocmiwait,
186 	.chars_in_buffer =		cypress_chars_in_buffer,
187 	.throttle =			cypress_throttle,
188 	.unthrottle =			cypress_unthrottle,
189 	.read_int_callback =		cypress_read_int_callback,
190 	.write_int_callback =		cypress_write_int_callback,
191 };
192 
193 static struct usb_serial_driver cypress_ca42v2_device = {
194 	.driver = {
195 		.owner =		THIS_MODULE,
196 		.name =			"nokiaca42v2",
197 	},
198 	.description =			"Nokia CA-42 V2 Adapter",
199 	.id_table =			id_table_nokiaca42v2,
200 	.num_ports =			1,
201 	.port_probe =			cypress_ca42v2_port_probe,
202 	.port_remove =			cypress_port_remove,
203 	.open =				cypress_open,
204 	.close =			cypress_close,
205 	.dtr_rts =			cypress_dtr_rts,
206 	.write =			cypress_write,
207 	.write_room =			cypress_write_room,
208 	.set_termios =			cypress_set_termios,
209 	.tiocmget =			cypress_tiocmget,
210 	.tiocmset =			cypress_tiocmset,
211 	.tiocmiwait =			usb_serial_generic_tiocmiwait,
212 	.chars_in_buffer =		cypress_chars_in_buffer,
213 	.throttle =			cypress_throttle,
214 	.unthrottle =			cypress_unthrottle,
215 	.read_int_callback =		cypress_read_int_callback,
216 	.write_int_callback =		cypress_write_int_callback,
217 };
218 
219 static struct usb_serial_driver * const serial_drivers[] = {
220 	&cypress_earthmate_device, &cypress_hidcom_device,
221 	&cypress_ca42v2_device, NULL
222 };
223 
224 /*****************************************************************************
225  * Cypress serial helper functions
226  *****************************************************************************/
227 
228 /* FRWD Dongle hidcom needs to skip reset and speed checks */
229 static inline bool is_frwd(struct usb_device *dev)
230 {
231 	return ((le16_to_cpu(dev->descriptor.idVendor) == VENDOR_ID_FRWD) &&
232 		(le16_to_cpu(dev->descriptor.idProduct) == PRODUCT_ID_CYPHIDCOM_FRWD));
233 }
234 
235 static int analyze_baud_rate(struct usb_serial_port *port, speed_t new_rate)
236 {
237 	struct cypress_private *priv;
238 	priv = usb_get_serial_port_data(port);
239 
240 	if (unstable_bauds)
241 		return new_rate;
242 
243 	/* FRWD Dongle uses 115200 bps */
244 	if (is_frwd(port->serial->dev))
245 		return new_rate;
246 
247 	/*
248 	 * The general purpose firmware for the Cypress M8 allows for
249 	 * a maximum speed of 57600bps (I have no idea whether DeLorme
250 	 * chose to use the general purpose firmware or not), if you
251 	 * need to modify this speed setting for your own project
252 	 * please add your own chiptype and modify the code likewise.
253 	 * The Cypress HID->COM device will work successfully up to
254 	 * 115200bps (but the actual throughput is around 3kBps).
255 	 */
256 	if (port->serial->dev->speed == USB_SPEED_LOW) {
257 		/*
258 		 * Mike Isely <isely@pobox.com> 2-Feb-2008: The
259 		 * Cypress app note that describes this mechanism
260 		 * states that the low-speed part can't handle more
261 		 * than 800 bytes/sec, in which case 4800 baud is the
262 		 * safest speed for a part like that.
263 		 */
264 		if (new_rate > 4800) {
265 			dev_dbg(&port->dev,
266 				"%s - failed setting baud rate, device incapable speed %d\n",
267 				__func__, new_rate);
268 			return -1;
269 		}
270 	}
271 	switch (priv->chiptype) {
272 	case CT_EARTHMATE:
273 		if (new_rate <= 600) {
274 			/* 300 and 600 baud rates are supported under
275 			 * the generic firmware, but are not used with
276 			 * NMEA and SiRF protocols */
277 			dev_dbg(&port->dev,
278 				"%s - failed setting baud rate, unsupported speed of %d on Earthmate GPS\n",
279 				__func__, new_rate);
280 			return -1;
281 		}
282 		break;
283 	default:
284 		break;
285 	}
286 	return new_rate;
287 }
288 
289 
290 /* This function can either set or retrieve the current serial line settings */
291 static int cypress_serial_control(struct tty_struct *tty,
292 	struct usb_serial_port *port, speed_t baud_rate, int data_bits,
293 	int stop_bits, int parity_enable, int parity_type, int reset,
294 	int cypress_request_type)
295 {
296 	int new_baudrate = 0, retval = 0, tries = 0;
297 	struct cypress_private *priv;
298 	struct device *dev = &port->dev;
299 	u8 *feature_buffer;
300 	const unsigned int feature_len = 5;
301 	unsigned long flags;
302 
303 	priv = usb_get_serial_port_data(port);
304 
305 	if (!priv->comm_is_ok)
306 		return -ENODEV;
307 
308 	feature_buffer = kcalloc(feature_len, sizeof(u8), GFP_KERNEL);
309 	if (!feature_buffer)
310 		return -ENOMEM;
311 
312 	switch (cypress_request_type) {
313 	case CYPRESS_SET_CONFIG:
314 		/* 0 means 'Hang up' so doesn't change the true bit rate */
315 		new_baudrate = priv->baud_rate;
316 		if (baud_rate && baud_rate != priv->baud_rate) {
317 			dev_dbg(dev, "%s - baud rate is changing\n", __func__);
318 			retval = analyze_baud_rate(port, baud_rate);
319 			if (retval >= 0) {
320 				new_baudrate = retval;
321 				dev_dbg(dev, "%s - New baud rate set to %d\n",
322 					__func__, new_baudrate);
323 			}
324 		}
325 		dev_dbg(dev, "%s - baud rate is being sent as %d\n", __func__,
326 			new_baudrate);
327 
328 		/* fill the feature_buffer with new configuration */
329 		put_unaligned_le32(new_baudrate, feature_buffer);
330 		feature_buffer[4] |= data_bits - 5;   /* assign data bits in 2 bit space ( max 3 ) */
331 		/* 1 bit gap */
332 		feature_buffer[4] |= (stop_bits << 3);   /* assign stop bits in 1 bit space */
333 		feature_buffer[4] |= (parity_enable << 4);   /* assign parity flag in 1 bit space */
334 		feature_buffer[4] |= (parity_type << 5);   /* assign parity type in 1 bit space */
335 		/* 1 bit gap */
336 		feature_buffer[4] |= (reset << 7);   /* assign reset at end of byte, 1 bit space */
337 
338 		dev_dbg(dev, "%s - device is being sent this feature report:\n", __func__);
339 		dev_dbg(dev, "%s - %02X - %02X - %02X - %02X - %02X\n", __func__,
340 			feature_buffer[0], feature_buffer[1],
341 			feature_buffer[2], feature_buffer[3],
342 			feature_buffer[4]);
343 
344 		do {
345 			retval = usb_control_msg(port->serial->dev,
346 					usb_sndctrlpipe(port->serial->dev, 0),
347 					HID_REQ_SET_REPORT,
348 					USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
349 					0x0300, 0, feature_buffer,
350 					feature_len, 500);
351 
352 			if (tries++ >= 3)
353 				break;
354 
355 		} while (retval != feature_len &&
356 			 retval != -ENODEV);
357 
358 		if (retval != feature_len) {
359 			dev_err(dev, "%s - failed sending serial line settings - %d\n",
360 				__func__, retval);
361 			cypress_set_dead(port);
362 		} else {
363 			spin_lock_irqsave(&priv->lock, flags);
364 			priv->baud_rate = new_baudrate;
365 			priv->current_config = feature_buffer[4];
366 			spin_unlock_irqrestore(&priv->lock, flags);
367 			/* If we asked for a speed change encode it */
368 			if (baud_rate)
369 				tty_encode_baud_rate(tty,
370 					new_baudrate, new_baudrate);
371 		}
372 	break;
373 	case CYPRESS_GET_CONFIG:
374 		if (priv->get_cfg_unsafe) {
375 			/* Not implemented for this device,
376 			   and if we try to do it we're likely
377 			   to crash the hardware. */
378 			retval = -ENOTTY;
379 			goto out;
380 		}
381 		dev_dbg(dev, "%s - retrieving serial line settings\n", __func__);
382 		do {
383 			retval = usb_control_msg(port->serial->dev,
384 					usb_rcvctrlpipe(port->serial->dev, 0),
385 					HID_REQ_GET_REPORT,
386 					USB_DIR_IN | USB_RECIP_INTERFACE | USB_TYPE_CLASS,
387 					0x0300, 0, feature_buffer,
388 					feature_len, 500);
389 
390 			if (tries++ >= 3)
391 				break;
392 		} while (retval != feature_len
393 						&& retval != -ENODEV);
394 
395 		if (retval != feature_len) {
396 			dev_err(dev, "%s - failed to retrieve serial line settings - %d\n",
397 				__func__, retval);
398 			cypress_set_dead(port);
399 			goto out;
400 		} else {
401 			spin_lock_irqsave(&priv->lock, flags);
402 			/* store the config in one byte, and later
403 			   use bit masks to check values */
404 			priv->current_config = feature_buffer[4];
405 			priv->baud_rate = get_unaligned_le32(feature_buffer);
406 			spin_unlock_irqrestore(&priv->lock, flags);
407 		}
408 	}
409 	spin_lock_irqsave(&priv->lock, flags);
410 	++priv->cmd_count;
411 	spin_unlock_irqrestore(&priv->lock, flags);
412 out:
413 	kfree(feature_buffer);
414 	return retval;
415 } /* cypress_serial_control */
416 
417 
418 static void cypress_set_dead(struct usb_serial_port *port)
419 {
420 	struct cypress_private *priv = usb_get_serial_port_data(port);
421 	unsigned long flags;
422 
423 	spin_lock_irqsave(&priv->lock, flags);
424 	if (!priv->comm_is_ok) {
425 		spin_unlock_irqrestore(&priv->lock, flags);
426 		return;
427 	}
428 	priv->comm_is_ok = 0;
429 	spin_unlock_irqrestore(&priv->lock, flags);
430 
431 	dev_err(&port->dev, "cypress_m8 suspending failing port %d - "
432 		"interval might be too short\n", port->port_number);
433 }
434 
435 
436 /*****************************************************************************
437  * Cypress serial driver functions
438  *****************************************************************************/
439 
440 
441 static int cypress_generic_port_probe(struct usb_serial_port *port)
442 {
443 	struct usb_serial *serial = port->serial;
444 	struct cypress_private *priv;
445 
446 	if (!port->interrupt_out_urb || !port->interrupt_in_urb) {
447 		dev_err(&port->dev, "required endpoint is missing\n");
448 		return -ENODEV;
449 	}
450 
451 	priv = kzalloc(sizeof(struct cypress_private), GFP_KERNEL);
452 	if (!priv)
453 		return -ENOMEM;
454 
455 	priv->comm_is_ok = !0;
456 	spin_lock_init(&priv->lock);
457 	if (kfifo_alloc(&priv->write_fifo, CYPRESS_BUF_SIZE, GFP_KERNEL)) {
458 		kfree(priv);
459 		return -ENOMEM;
460 	}
461 
462 	/* Skip reset for FRWD device. It is a workaound:
463 	   device hangs if it receives SET_CONFIGURE in Configured
464 	   state. */
465 	if (!is_frwd(serial->dev))
466 		usb_reset_configuration(serial->dev);
467 
468 	priv->cmd_ctrl = 0;
469 	priv->line_control = 0;
470 	priv->rx_flags = 0;
471 	/* Default packet format setting is determined by packet size.
472 	   Anything with a size larger then 9 must have a separate
473 	   count field since the 3 bit count field is otherwise too
474 	   small.  Otherwise we can use the slightly more compact
475 	   format.  This is in accordance with the cypress_m8 serial
476 	   converter app note. */
477 	if (port->interrupt_out_size > 9)
478 		priv->pkt_fmt = packet_format_1;
479 	else
480 		priv->pkt_fmt = packet_format_2;
481 
482 	if (interval > 0) {
483 		priv->write_urb_interval = interval;
484 		priv->read_urb_interval = interval;
485 		dev_dbg(&port->dev, "%s - read & write intervals forced to %d\n",
486 			__func__, interval);
487 	} else {
488 		priv->write_urb_interval = port->interrupt_out_urb->interval;
489 		priv->read_urb_interval = port->interrupt_in_urb->interval;
490 		dev_dbg(&port->dev, "%s - intervals: read=%d write=%d\n",
491 			__func__, priv->read_urb_interval,
492 			priv->write_urb_interval);
493 	}
494 	usb_set_serial_port_data(port, priv);
495 
496 	port->port.drain_delay = 256;
497 
498 	return 0;
499 }
500 
501 
502 static int cypress_earthmate_port_probe(struct usb_serial_port *port)
503 {
504 	struct usb_serial *serial = port->serial;
505 	struct cypress_private *priv;
506 	int ret;
507 
508 	ret = cypress_generic_port_probe(port);
509 	if (ret) {
510 		dev_dbg(&port->dev, "%s - Failed setting up port\n", __func__);
511 		return ret;
512 	}
513 
514 	priv = usb_get_serial_port_data(port);
515 	priv->chiptype = CT_EARTHMATE;
516 	/* All Earthmate devices use the separated-count packet
517 	   format!  Idiotic. */
518 	priv->pkt_fmt = packet_format_1;
519 	if (serial->dev->descriptor.idProduct !=
520 				cpu_to_le16(PRODUCT_ID_EARTHMATEUSB)) {
521 		/* The old original USB Earthmate seemed able to
522 		   handle GET_CONFIG requests; everything they've
523 		   produced since that time crashes if this command is
524 		   attempted :-( */
525 		dev_dbg(&port->dev,
526 			"%s - Marking this device as unsafe for GET_CONFIG commands\n",
527 			__func__);
528 		priv->get_cfg_unsafe = !0;
529 	}
530 
531 	return 0;
532 }
533 
534 static int cypress_hidcom_port_probe(struct usb_serial_port *port)
535 {
536 	struct cypress_private *priv;
537 	int ret;
538 
539 	ret = cypress_generic_port_probe(port);
540 	if (ret) {
541 		dev_dbg(&port->dev, "%s - Failed setting up port\n", __func__);
542 		return ret;
543 	}
544 
545 	priv = usb_get_serial_port_data(port);
546 	priv->chiptype = CT_CYPHIDCOM;
547 
548 	return 0;
549 }
550 
551 static int cypress_ca42v2_port_probe(struct usb_serial_port *port)
552 {
553 	struct cypress_private *priv;
554 	int ret;
555 
556 	ret = cypress_generic_port_probe(port);
557 	if (ret) {
558 		dev_dbg(&port->dev, "%s - Failed setting up port\n", __func__);
559 		return ret;
560 	}
561 
562 	priv = usb_get_serial_port_data(port);
563 	priv->chiptype = CT_CA42V2;
564 
565 	return 0;
566 }
567 
568 static void cypress_port_remove(struct usb_serial_port *port)
569 {
570 	struct cypress_private *priv;
571 
572 	priv = usb_get_serial_port_data(port);
573 
574 	kfifo_free(&priv->write_fifo);
575 	kfree(priv);
576 }
577 
578 static int cypress_open(struct tty_struct *tty, struct usb_serial_port *port)
579 {
580 	struct cypress_private *priv = usb_get_serial_port_data(port);
581 	struct usb_serial *serial = port->serial;
582 	unsigned long flags;
583 	int result = 0;
584 
585 	if (!priv->comm_is_ok)
586 		return -EIO;
587 
588 	/* clear halts before open */
589 	usb_clear_halt(serial->dev, 0x81);
590 	usb_clear_halt(serial->dev, 0x02);
591 
592 	spin_lock_irqsave(&priv->lock, flags);
593 	/* reset read/write statistics */
594 	priv->bytes_in = 0;
595 	priv->bytes_out = 0;
596 	priv->cmd_count = 0;
597 	priv->rx_flags = 0;
598 	spin_unlock_irqrestore(&priv->lock, flags);
599 
600 	/* Set termios */
601 	cypress_send(port);
602 
603 	if (tty)
604 		cypress_set_termios(tty, port, NULL);
605 
606 	/* setup the port and start reading from the device */
607 	usb_fill_int_urb(port->interrupt_in_urb, serial->dev,
608 		usb_rcvintpipe(serial->dev, port->interrupt_in_endpointAddress),
609 		port->interrupt_in_urb->transfer_buffer,
610 		port->interrupt_in_urb->transfer_buffer_length,
611 		cypress_read_int_callback, port, priv->read_urb_interval);
612 	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
613 
614 	if (result) {
615 		dev_err(&port->dev,
616 			"%s - failed submitting read urb, error %d\n",
617 							__func__, result);
618 		cypress_set_dead(port);
619 	}
620 
621 	return result;
622 } /* cypress_open */
623 
624 static void cypress_dtr_rts(struct usb_serial_port *port, int on)
625 {
626 	struct cypress_private *priv = usb_get_serial_port_data(port);
627 	/* drop dtr and rts */
628 	spin_lock_irq(&priv->lock);
629 	if (on == 0)
630 		priv->line_control = 0;
631 	else
632 		priv->line_control = CONTROL_DTR | CONTROL_RTS;
633 	priv->cmd_ctrl = 1;
634 	spin_unlock_irq(&priv->lock);
635 	cypress_write(NULL, port, NULL, 0);
636 }
637 
638 static void cypress_close(struct usb_serial_port *port)
639 {
640 	struct cypress_private *priv = usb_get_serial_port_data(port);
641 	unsigned long flags;
642 
643 	spin_lock_irqsave(&priv->lock, flags);
644 	kfifo_reset_out(&priv->write_fifo);
645 	spin_unlock_irqrestore(&priv->lock, flags);
646 
647 	dev_dbg(&port->dev, "%s - stopping urbs\n", __func__);
648 	usb_kill_urb(port->interrupt_in_urb);
649 	usb_kill_urb(port->interrupt_out_urb);
650 
651 	if (stats)
652 		dev_info(&port->dev, "Statistics: %d Bytes In | %d Bytes Out | %d Commands Issued\n",
653 			priv->bytes_in, priv->bytes_out, priv->cmd_count);
654 } /* cypress_close */
655 
656 
657 static int cypress_write(struct tty_struct *tty, struct usb_serial_port *port,
658 					const unsigned char *buf, int count)
659 {
660 	struct cypress_private *priv = usb_get_serial_port_data(port);
661 
662 	dev_dbg(&port->dev, "%s - %d bytes\n", __func__, count);
663 
664 	/* line control commands, which need to be executed immediately,
665 	   are not put into the buffer for obvious reasons.
666 	 */
667 	if (priv->cmd_ctrl) {
668 		count = 0;
669 		goto finish;
670 	}
671 
672 	if (!count)
673 		return count;
674 
675 	count = kfifo_in_locked(&priv->write_fifo, buf, count, &priv->lock);
676 
677 finish:
678 	cypress_send(port);
679 
680 	return count;
681 } /* cypress_write */
682 
683 
684 static void cypress_send(struct usb_serial_port *port)
685 {
686 	int count = 0, result, offset, actual_size;
687 	struct cypress_private *priv = usb_get_serial_port_data(port);
688 	struct device *dev = &port->dev;
689 	unsigned long flags;
690 
691 	if (!priv->comm_is_ok)
692 		return;
693 
694 	dev_dbg(dev, "%s - interrupt out size is %d\n", __func__,
695 		port->interrupt_out_size);
696 
697 	spin_lock_irqsave(&priv->lock, flags);
698 	if (priv->write_urb_in_use) {
699 		dev_dbg(dev, "%s - can't write, urb in use\n", __func__);
700 		spin_unlock_irqrestore(&priv->lock, flags);
701 		return;
702 	}
703 	spin_unlock_irqrestore(&priv->lock, flags);
704 
705 	/* clear buffer */
706 	memset(port->interrupt_out_urb->transfer_buffer, 0,
707 						port->interrupt_out_size);
708 
709 	spin_lock_irqsave(&priv->lock, flags);
710 	switch (priv->pkt_fmt) {
711 	default:
712 	case packet_format_1:
713 		/* this is for the CY7C64013... */
714 		offset = 2;
715 		port->interrupt_out_buffer[0] = priv->line_control;
716 		break;
717 	case packet_format_2:
718 		/* this is for the CY7C63743... */
719 		offset = 1;
720 		port->interrupt_out_buffer[0] = priv->line_control;
721 		break;
722 	}
723 
724 	if (priv->line_control & CONTROL_RESET)
725 		priv->line_control &= ~CONTROL_RESET;
726 
727 	if (priv->cmd_ctrl) {
728 		priv->cmd_count++;
729 		dev_dbg(dev, "%s - line control command being issued\n", __func__);
730 		spin_unlock_irqrestore(&priv->lock, flags);
731 		goto send;
732 	} else
733 		spin_unlock_irqrestore(&priv->lock, flags);
734 
735 	count = kfifo_out_locked(&priv->write_fifo,
736 					&port->interrupt_out_buffer[offset],
737 					port->interrupt_out_size - offset,
738 					&priv->lock);
739 	if (count == 0)
740 		return;
741 
742 	switch (priv->pkt_fmt) {
743 	default:
744 	case packet_format_1:
745 		port->interrupt_out_buffer[1] = count;
746 		break;
747 	case packet_format_2:
748 		port->interrupt_out_buffer[0] |= count;
749 	}
750 
751 	dev_dbg(dev, "%s - count is %d\n", __func__, count);
752 
753 send:
754 	spin_lock_irqsave(&priv->lock, flags);
755 	priv->write_urb_in_use = 1;
756 	spin_unlock_irqrestore(&priv->lock, flags);
757 
758 	if (priv->cmd_ctrl)
759 		actual_size = 1;
760 	else
761 		actual_size = count +
762 			      (priv->pkt_fmt == packet_format_1 ? 2 : 1);
763 
764 	usb_serial_debug_data(dev, __func__, port->interrupt_out_size,
765 			      port->interrupt_out_urb->transfer_buffer);
766 
767 	usb_fill_int_urb(port->interrupt_out_urb, port->serial->dev,
768 		usb_sndintpipe(port->serial->dev, port->interrupt_out_endpointAddress),
769 		port->interrupt_out_buffer, actual_size,
770 		cypress_write_int_callback, port, priv->write_urb_interval);
771 	result = usb_submit_urb(port->interrupt_out_urb, GFP_ATOMIC);
772 	if (result) {
773 		dev_err_console(port,
774 				"%s - failed submitting write urb, error %d\n",
775 							__func__, result);
776 		priv->write_urb_in_use = 0;
777 		cypress_set_dead(port);
778 	}
779 
780 	spin_lock_irqsave(&priv->lock, flags);
781 	if (priv->cmd_ctrl)
782 		priv->cmd_ctrl = 0;
783 
784 	/* do not count the line control and size bytes */
785 	priv->bytes_out += count;
786 	spin_unlock_irqrestore(&priv->lock, flags);
787 
788 	usb_serial_port_softint(port);
789 } /* cypress_send */
790 
791 
792 /* returns how much space is available in the soft buffer */
793 static unsigned int cypress_write_room(struct tty_struct *tty)
794 {
795 	struct usb_serial_port *port = tty->driver_data;
796 	struct cypress_private *priv = usb_get_serial_port_data(port);
797 	unsigned int room;
798 	unsigned long flags;
799 
800 	spin_lock_irqsave(&priv->lock, flags);
801 	room = kfifo_avail(&priv->write_fifo);
802 	spin_unlock_irqrestore(&priv->lock, flags);
803 
804 	dev_dbg(&port->dev, "%s - returns %u\n", __func__, room);
805 	return room;
806 }
807 
808 
809 static int cypress_tiocmget(struct tty_struct *tty)
810 {
811 	struct usb_serial_port *port = tty->driver_data;
812 	struct cypress_private *priv = usb_get_serial_port_data(port);
813 	__u8 status, control;
814 	unsigned int result = 0;
815 	unsigned long flags;
816 
817 	spin_lock_irqsave(&priv->lock, flags);
818 	control = priv->line_control;
819 	status = priv->current_status;
820 	spin_unlock_irqrestore(&priv->lock, flags);
821 
822 	result = ((control & CONTROL_DTR)        ? TIOCM_DTR : 0)
823 		| ((control & CONTROL_RTS)       ? TIOCM_RTS : 0)
824 		| ((status & UART_CTS)        ? TIOCM_CTS : 0)
825 		| ((status & UART_DSR)        ? TIOCM_DSR : 0)
826 		| ((status & UART_RI)         ? TIOCM_RI  : 0)
827 		| ((status & UART_CD)         ? TIOCM_CD  : 0);
828 
829 	dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
830 
831 	return result;
832 }
833 
834 
835 static int cypress_tiocmset(struct tty_struct *tty,
836 			       unsigned int set, unsigned int clear)
837 {
838 	struct usb_serial_port *port = tty->driver_data;
839 	struct cypress_private *priv = usb_get_serial_port_data(port);
840 	unsigned long flags;
841 
842 	spin_lock_irqsave(&priv->lock, flags);
843 	if (set & TIOCM_RTS)
844 		priv->line_control |= CONTROL_RTS;
845 	if (set & TIOCM_DTR)
846 		priv->line_control |= CONTROL_DTR;
847 	if (clear & TIOCM_RTS)
848 		priv->line_control &= ~CONTROL_RTS;
849 	if (clear & TIOCM_DTR)
850 		priv->line_control &= ~CONTROL_DTR;
851 	priv->cmd_ctrl = 1;
852 	spin_unlock_irqrestore(&priv->lock, flags);
853 
854 	return cypress_write(tty, port, NULL, 0);
855 }
856 
857 static void cypress_earthmate_init_termios(struct tty_struct *tty)
858 {
859 	tty_encode_baud_rate(tty, 4800, 4800);
860 }
861 
862 static void cypress_set_termios(struct tty_struct *tty,
863 				struct usb_serial_port *port,
864 				const struct ktermios *old_termios)
865 {
866 	struct cypress_private *priv = usb_get_serial_port_data(port);
867 	struct device *dev = &port->dev;
868 	int data_bits, stop_bits, parity_type, parity_enable;
869 	unsigned int cflag;
870 	unsigned long flags;
871 	__u8 oldlines;
872 	int linechange = 0;
873 
874 	/* Unsupported features need clearing */
875 	tty->termios.c_cflag &= ~(CMSPAR|CRTSCTS);
876 
877 	cflag = tty->termios.c_cflag;
878 
879 	/* set number of data bits, parity, stop bits */
880 	/* when parity is disabled the parity type bit is ignored */
881 
882 	/* 1 means 2 stop bits, 0 means 1 stop bit */
883 	stop_bits = cflag & CSTOPB ? 1 : 0;
884 
885 	if (cflag & PARENB) {
886 		parity_enable = 1;
887 		/* 1 means odd parity, 0 means even parity */
888 		parity_type = cflag & PARODD ? 1 : 0;
889 	} else
890 		parity_enable = parity_type = 0;
891 
892 	data_bits = tty_get_char_size(cflag);
893 
894 	spin_lock_irqsave(&priv->lock, flags);
895 	oldlines = priv->line_control;
896 	if ((cflag & CBAUD) == B0) {
897 		/* drop dtr and rts */
898 		dev_dbg(dev, "%s - dropping the lines, baud rate 0bps\n", __func__);
899 		priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
900 	} else
901 		priv->line_control = (CONTROL_DTR | CONTROL_RTS);
902 	spin_unlock_irqrestore(&priv->lock, flags);
903 
904 	dev_dbg(dev, "%s - sending %d stop_bits, %d parity_enable, %d parity_type, %d data_bits (+5)\n",
905 		__func__, stop_bits, parity_enable, parity_type, data_bits);
906 
907 	cypress_serial_control(tty, port, tty_get_baud_rate(tty),
908 			data_bits, stop_bits,
909 			parity_enable, parity_type,
910 			0, CYPRESS_SET_CONFIG);
911 
912 	/* we perform a CYPRESS_GET_CONFIG so that the current settings are
913 	 * filled into the private structure this should confirm that all is
914 	 * working if it returns what we just set */
915 	cypress_serial_control(tty, port, 0, 0, 0, 0, 0, 0, CYPRESS_GET_CONFIG);
916 
917 	/* Here we can define custom tty settings for devices; the main tty
918 	 * termios flag base comes from empeg.c */
919 
920 	spin_lock_irqsave(&priv->lock, flags);
921 	if (priv->chiptype == CT_EARTHMATE && priv->baud_rate == 4800) {
922 		dev_dbg(dev, "Using custom termios settings for a baud rate of 4800bps.\n");
923 		/* define custom termios settings for NMEA protocol */
924 
925 		tty->termios.c_iflag /* input modes - */
926 			&= ~(IGNBRK  /* disable ignore break */
927 			| BRKINT     /* disable break causes interrupt */
928 			| PARMRK     /* disable mark parity errors */
929 			| ISTRIP     /* disable clear high bit of input char */
930 			| INLCR      /* disable translate NL to CR */
931 			| IGNCR      /* disable ignore CR */
932 			| ICRNL      /* disable translate CR to NL */
933 			| IXON);     /* disable enable XON/XOFF flow control */
934 
935 		tty->termios.c_oflag /* output modes */
936 			&= ~OPOST;    /* disable postprocess output char */
937 
938 		tty->termios.c_lflag /* line discipline modes */
939 			&= ~(ECHO     /* disable echo input characters */
940 			| ECHONL      /* disable echo new line */
941 			| ICANON      /* disable erase, kill, werase, and rprnt
942 					 special characters */
943 			| ISIG        /* disable interrupt, quit, and suspend
944 					 special characters */
945 			| IEXTEN);    /* disable non-POSIX special characters */
946 	} /* CT_CYPHIDCOM: Application should handle this for device */
947 
948 	linechange = (priv->line_control != oldlines);
949 	spin_unlock_irqrestore(&priv->lock, flags);
950 
951 	/* if necessary, set lines */
952 	if (linechange) {
953 		priv->cmd_ctrl = 1;
954 		cypress_write(tty, port, NULL, 0);
955 	}
956 } /* cypress_set_termios */
957 
958 
959 /* returns amount of data still left in soft buffer */
960 static unsigned int cypress_chars_in_buffer(struct tty_struct *tty)
961 {
962 	struct usb_serial_port *port = tty->driver_data;
963 	struct cypress_private *priv = usb_get_serial_port_data(port);
964 	unsigned int chars;
965 	unsigned long flags;
966 
967 	spin_lock_irqsave(&priv->lock, flags);
968 	chars = kfifo_len(&priv->write_fifo);
969 	spin_unlock_irqrestore(&priv->lock, flags);
970 
971 	dev_dbg(&port->dev, "%s - returns %u\n", __func__, chars);
972 	return chars;
973 }
974 
975 
976 static void cypress_throttle(struct tty_struct *tty)
977 {
978 	struct usb_serial_port *port = tty->driver_data;
979 	struct cypress_private *priv = usb_get_serial_port_data(port);
980 
981 	spin_lock_irq(&priv->lock);
982 	priv->rx_flags = THROTTLED;
983 	spin_unlock_irq(&priv->lock);
984 }
985 
986 
987 static void cypress_unthrottle(struct tty_struct *tty)
988 {
989 	struct usb_serial_port *port = tty->driver_data;
990 	struct cypress_private *priv = usb_get_serial_port_data(port);
991 	int actually_throttled, result;
992 
993 	spin_lock_irq(&priv->lock);
994 	actually_throttled = priv->rx_flags & ACTUALLY_THROTTLED;
995 	priv->rx_flags = 0;
996 	spin_unlock_irq(&priv->lock);
997 
998 	if (!priv->comm_is_ok)
999 		return;
1000 
1001 	if (actually_throttled) {
1002 		result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
1003 		if (result) {
1004 			dev_err(&port->dev, "%s - failed submitting read urb, "
1005 					"error %d\n", __func__, result);
1006 			cypress_set_dead(port);
1007 		}
1008 	}
1009 }
1010 
1011 
1012 static void cypress_read_int_callback(struct urb *urb)
1013 {
1014 	struct usb_serial_port *port = urb->context;
1015 	struct cypress_private *priv = usb_get_serial_port_data(port);
1016 	struct device *dev = &urb->dev->dev;
1017 	struct tty_struct *tty;
1018 	unsigned char *data = urb->transfer_buffer;
1019 	unsigned long flags;
1020 	char tty_flag = TTY_NORMAL;
1021 	int bytes = 0;
1022 	int result;
1023 	int i = 0;
1024 	int status = urb->status;
1025 
1026 	switch (status) {
1027 	case 0: /* success */
1028 		break;
1029 	case -ECONNRESET:
1030 	case -ENOENT:
1031 	case -ESHUTDOWN:
1032 		/* precursor to disconnect so just go away */
1033 		return;
1034 	case -EPIPE:
1035 		/* Can't call usb_clear_halt while in_interrupt */
1036 		fallthrough;
1037 	default:
1038 		/* something ugly is going on... */
1039 		dev_err(dev, "%s - unexpected nonzero read status received: %d\n",
1040 			__func__, status);
1041 		cypress_set_dead(port);
1042 		return;
1043 	}
1044 
1045 	spin_lock_irqsave(&priv->lock, flags);
1046 	if (priv->rx_flags & THROTTLED) {
1047 		dev_dbg(dev, "%s - now throttling\n", __func__);
1048 		priv->rx_flags |= ACTUALLY_THROTTLED;
1049 		spin_unlock_irqrestore(&priv->lock, flags);
1050 		return;
1051 	}
1052 	spin_unlock_irqrestore(&priv->lock, flags);
1053 
1054 	tty = tty_port_tty_get(&port->port);
1055 	if (!tty) {
1056 		dev_dbg(dev, "%s - bad tty pointer - exiting\n", __func__);
1057 		return;
1058 	}
1059 
1060 	spin_lock_irqsave(&priv->lock, flags);
1061 	result = urb->actual_length;
1062 	switch (priv->pkt_fmt) {
1063 	default:
1064 	case packet_format_1:
1065 		/* This is for the CY7C64013... */
1066 		priv->current_status = data[0] & 0xF8;
1067 		bytes = data[1] + 2;
1068 		i = 2;
1069 		break;
1070 	case packet_format_2:
1071 		/* This is for the CY7C63743... */
1072 		priv->current_status = data[0] & 0xF8;
1073 		bytes = (data[0] & 0x07) + 1;
1074 		i = 1;
1075 		break;
1076 	}
1077 	spin_unlock_irqrestore(&priv->lock, flags);
1078 	if (result < bytes) {
1079 		dev_dbg(dev,
1080 			"%s - wrong packet size - received %d bytes but packet said %d bytes\n",
1081 			__func__, result, bytes);
1082 		goto continue_read;
1083 	}
1084 
1085 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
1086 
1087 	spin_lock_irqsave(&priv->lock, flags);
1088 	/* check to see if status has changed */
1089 	if (priv->current_status != priv->prev_status) {
1090 		u8 delta = priv->current_status ^ priv->prev_status;
1091 
1092 		if (delta & UART_MSR_MASK) {
1093 			if (delta & UART_CTS)
1094 				port->icount.cts++;
1095 			if (delta & UART_DSR)
1096 				port->icount.dsr++;
1097 			if (delta & UART_RI)
1098 				port->icount.rng++;
1099 			if (delta & UART_CD)
1100 				port->icount.dcd++;
1101 
1102 			wake_up_interruptible(&port->port.delta_msr_wait);
1103 		}
1104 
1105 		priv->prev_status = priv->current_status;
1106 	}
1107 	spin_unlock_irqrestore(&priv->lock, flags);
1108 
1109 	/* hangup, as defined in acm.c... this might be a bad place for it
1110 	 * though */
1111 	if (tty && !C_CLOCAL(tty) && !(priv->current_status & UART_CD)) {
1112 		dev_dbg(dev, "%s - calling hangup\n", __func__);
1113 		tty_hangup(tty);
1114 		goto continue_read;
1115 	}
1116 
1117 	/* There is one error bit... I'm assuming it is a parity error
1118 	 * indicator as the generic firmware will set this bit to 1 if a
1119 	 * parity error occurs.
1120 	 * I can not find reference to any other error events. */
1121 	spin_lock_irqsave(&priv->lock, flags);
1122 	if (priv->current_status & CYP_ERROR) {
1123 		spin_unlock_irqrestore(&priv->lock, flags);
1124 		tty_flag = TTY_PARITY;
1125 		dev_dbg(dev, "%s - Parity Error detected\n", __func__);
1126 	} else
1127 		spin_unlock_irqrestore(&priv->lock, flags);
1128 
1129 	/* process read if there is data other than line status */
1130 	if (bytes > i) {
1131 		tty_insert_flip_string_fixed_flag(&port->port, data + i,
1132 				tty_flag, bytes - i);
1133 		tty_flip_buffer_push(&port->port);
1134 	}
1135 
1136 	spin_lock_irqsave(&priv->lock, flags);
1137 	/* control and status byte(s) are also counted */
1138 	priv->bytes_in += bytes;
1139 	spin_unlock_irqrestore(&priv->lock, flags);
1140 
1141 continue_read:
1142 	tty_kref_put(tty);
1143 
1144 	/* Continue trying to always read */
1145 
1146 	if (priv->comm_is_ok) {
1147 		usb_fill_int_urb(port->interrupt_in_urb, port->serial->dev,
1148 				usb_rcvintpipe(port->serial->dev,
1149 					port->interrupt_in_endpointAddress),
1150 				port->interrupt_in_urb->transfer_buffer,
1151 				port->interrupt_in_urb->transfer_buffer_length,
1152 				cypress_read_int_callback, port,
1153 				priv->read_urb_interval);
1154 		result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
1155 		if (result && result != -EPERM) {
1156 			dev_err(dev, "%s - failed resubmitting read urb, error %d\n",
1157 				__func__, result);
1158 			cypress_set_dead(port);
1159 		}
1160 	}
1161 } /* cypress_read_int_callback */
1162 
1163 
1164 static void cypress_write_int_callback(struct urb *urb)
1165 {
1166 	struct usb_serial_port *port = urb->context;
1167 	struct cypress_private *priv = usb_get_serial_port_data(port);
1168 	struct device *dev = &urb->dev->dev;
1169 	int status = urb->status;
1170 
1171 	switch (status) {
1172 	case 0:
1173 		/* success */
1174 		break;
1175 	case -ECONNRESET:
1176 	case -ENOENT:
1177 	case -ESHUTDOWN:
1178 		/* this urb is terminated, clean up */
1179 		dev_dbg(dev, "%s - urb shutting down with status: %d\n",
1180 			__func__, status);
1181 		priv->write_urb_in_use = 0;
1182 		return;
1183 	case -EPIPE:
1184 		/* Cannot call usb_clear_halt while in_interrupt */
1185 		fallthrough;
1186 	default:
1187 		dev_err(dev, "%s - unexpected nonzero write status received: %d\n",
1188 			__func__, status);
1189 		cypress_set_dead(port);
1190 		break;
1191 	}
1192 	priv->write_urb_in_use = 0;
1193 
1194 	/* send any buffered data */
1195 	cypress_send(port);
1196 }
1197 
1198 module_usb_serial_driver(serial_drivers, id_table_combined);
1199 
1200 MODULE_AUTHOR(DRIVER_AUTHOR);
1201 MODULE_DESCRIPTION(DRIVER_DESC);
1202 MODULE_LICENSE("GPL");
1203 
1204 module_param(stats, bool, 0644);
1205 MODULE_PARM_DESC(stats, "Enable statistics or not");
1206 module_param(interval, int, 0644);
1207 MODULE_PARM_DESC(interval, "Overrides interrupt interval");
1208 module_param(unstable_bauds, bool, 0644);
1209 MODULE_PARM_DESC(unstable_bauds, "Allow unstable baud rates");
1210