xref: /linux/drivers/usb/serial/garmin_gps.c (revision 0c80bdfc9aa624b4a6c33c30ad11e81bf6407c36)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Garmin GPS driver
4  *
5  * Copyright (C) 2006-2011 Hermann Kneissel herkne@gmx.de
6  *
7  * The latest version of the driver can be found at
8  * http://sourceforge.net/projects/garmin-gps/
9  *
10  * This driver has been derived from v2.1 of the visor driver.
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/errno.h>
15 #include <linux/slab.h>
16 #include <linux/timer.h>
17 #include <linux/tty.h>
18 #include <linux/tty_driver.h>
19 #include <linux/tty_flip.h>
20 #include <linux/module.h>
21 #include <linux/spinlock.h>
22 #include <linux/uaccess.h>
23 #include <linux/atomic.h>
24 #include <linux/usb.h>
25 #include <linux/usb/serial.h>
26 
27 /* the mode to be set when the port ist opened */
28 static int initial_mode = 1;
29 
30 #define GARMIN_VENDOR_ID             0x091E
31 
32 /*
33  * Version Information
34  */
35 
36 #define VERSION_MAJOR	0
37 #define VERSION_MINOR	36
38 
39 #define _STR(s) #s
40 #define _DRIVER_VERSION(a, b) "v" _STR(a) "." _STR(b)
41 #define DRIVER_VERSION _DRIVER_VERSION(VERSION_MAJOR, VERSION_MINOR)
42 #define DRIVER_AUTHOR "hermann kneissel"
43 #define DRIVER_DESC "garmin gps driver"
44 
45 /* error codes returned by the driver */
46 #define EINVPKT	1000	/* invalid packet structure */
47 
48 
49 /* size of the header of a packet using the usb protocol */
50 #define GARMIN_PKTHDR_LENGTH	12
51 
52 /* max. possible size of a packet using the serial protocol */
53 #define MAX_SERIAL_PKT_SIZ (3 + 255 + 3)
54 
55 /*  max. possible size of a packet with worst case stuffing */
56 #define MAX_SERIAL_PKT_SIZ_STUFFED (MAX_SERIAL_PKT_SIZ + 256)
57 
58 /* size of a buffer able to hold a complete (no stuffing) packet
59  * (the document protocol does not contain packets with a larger
60  *  size, but in theory a packet may be 64k+12 bytes - if in
61  *  later protocol versions larger packet sizes occur, this value
62  *  should be increased accordingly, so the input buffer is always
63  *  large enough the store a complete packet inclusive header) */
64 #define GPS_IN_BUFSIZ  (GARMIN_PKTHDR_LENGTH+MAX_SERIAL_PKT_SIZ)
65 
66 /* size of a buffer able to hold a complete (incl. stuffing) packet */
67 #define GPS_OUT_BUFSIZ (GARMIN_PKTHDR_LENGTH+MAX_SERIAL_PKT_SIZ_STUFFED)
68 
69 /* where to place the packet id of a serial packet, so we can
70  * prepend the usb-packet header without the need to move the
71  * packets data */
72 #define GSP_INITIAL_OFFSET (GARMIN_PKTHDR_LENGTH-2)
73 
74 /* max. size of incoming private packets (header+1 param) */
75 #define PRIVPKTSIZ (GARMIN_PKTHDR_LENGTH+4)
76 
77 #define GARMIN_LAYERID_TRANSPORT  0
78 #define GARMIN_LAYERID_APPL      20
79 /* our own layer-id to use for some control mechanisms */
80 #define GARMIN_LAYERID_PRIVATE	0x01106E4B
81 
82 #define GARMIN_PKTID_PVT_DATA	51
83 #define GARMIN_PKTID_L001_COMMAND_DATA 10
84 
85 #define CMND_ABORT_TRANSFER 0
86 
87 /* packet ids used in private layer */
88 #define PRIV_PKTID_SET_DEBUG	1
89 #define PRIV_PKTID_SET_MODE	2
90 #define PRIV_PKTID_INFO_REQ	3
91 #define PRIV_PKTID_INFO_RESP	4
92 #define PRIV_PKTID_RESET_REQ	5
93 #define PRIV_PKTID_SET_DEF_MODE	6
94 
95 
96 #define ETX	0x03
97 #define DLE	0x10
98 #define ACK	0x06
99 #define NAK	0x15
100 
101 /* structure used to queue incoming packets */
102 struct garmin_packet {
103 	struct list_head  list;
104 	int               seq;
105 	/* the real size of the data array, always > 0 */
106 	int               size;
107 	__u8              data[] __counted_by(size);
108 };
109 
110 /* structure used to keep the current state of the driver */
111 struct garmin_data {
112 	__u8   state;
113 	__u16  flags;
114 	__u8   mode;
115 	__u8   count;
116 	__u8   pkt_id;
117 	__u32  serial_num;
118 	struct timer_list timer;
119 	struct usb_serial_port *port;
120 	int    seq_counter;
121 	int    insize;
122 	int    outsize;
123 	__u8   inbuffer [GPS_IN_BUFSIZ];  /* tty -> usb */
124 	__u8   outbuffer[GPS_OUT_BUFSIZ]; /* usb -> tty */
125 	__u8   privpkt[4*6];
126 	spinlock_t lock;
127 	struct list_head pktlist;
128 	struct usb_anchor write_urbs;
129 };
130 
131 
132 #define STATE_NEW            0
133 #define STATE_INITIAL_DELAY  1
134 #define STATE_TIMEOUT        2
135 #define STATE_SESSION_REQ1   3
136 #define STATE_SESSION_REQ2   4
137 #define STATE_ACTIVE         5
138 
139 #define STATE_RESET	     8
140 #define STATE_DISCONNECTED   9
141 #define STATE_WAIT_TTY_ACK  10
142 #define STATE_GSP_WAIT_DATA 11
143 
144 #define MODE_NATIVE          0
145 #define MODE_GARMIN_SERIAL   1
146 
147 /* Flags used in garmin_data.flags: */
148 #define FLAGS_SESSION_REPLY_MASK  0x00C0
149 #define FLAGS_SESSION_REPLY1_SEEN 0x0080
150 #define FLAGS_SESSION_REPLY2_SEEN 0x0040
151 #define FLAGS_BULK_IN_ACTIVE      0x0020
152 #define FLAGS_BULK_IN_RESTART     0x0010
153 #define FLAGS_THROTTLED           0x0008
154 #define APP_REQ_SEEN              0x0004
155 #define APP_RESP_SEEN             0x0002
156 #define CLEAR_HALT_REQUIRED       0x0001
157 
158 #define FLAGS_QUEUING             0x0100
159 #define FLAGS_DROP_DATA           0x0800
160 
161 #define FLAGS_GSP_SKIP            0x1000
162 #define FLAGS_GSP_DLESEEN         0x2000
163 
164 
165 
166 
167 
168 
169 /* function prototypes */
170 static int gsp_next_packet(struct garmin_data *garmin_data_p);
171 static int garmin_write_bulk(struct usb_serial_port *port,
172 			     const unsigned char *buf, int count,
173 			     int dismiss_ack);
174 
175 /* some special packets to be send or received */
176 static unsigned char const GARMIN_START_SESSION_REQ[]
177 	= { 0, 0, 0, 0,  5, 0, 0, 0, 0, 0, 0, 0 };
178 static unsigned char const GARMIN_START_SESSION_REPLY[]
179 	= { 0, 0, 0, 0,  6, 0, 0, 0, 4, 0, 0, 0 };
180 static unsigned char const GARMIN_BULK_IN_AVAIL_REPLY[]
181 	= { 0, 0, 0, 0,  2, 0, 0, 0, 0, 0, 0, 0 };
182 static unsigned char const GARMIN_STOP_TRANSFER_REQ[]
183 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 0, 0 };
184 static unsigned char const GARMIN_STOP_TRANSFER_REQ_V2[]
185 	= { 20, 0, 0, 0,  10, 0, 0, 0, 1, 0, 0, 0, 0 };
186 
187 /* packets currently unused, left as documentation */
188 #if 0
189 static unsigned char const GARMIN_APP_LAYER_REPLY[]
190 	= { 0x14, 0, 0, 0 };
191 static unsigned char const GARMIN_START_PVT_REQ[]
192 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 49, 0 };
193 static unsigned char const GARMIN_STOP_PVT_REQ[]
194 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 50, 0 };
195 static unsigned char const PRIVATE_REQ[]
196 	=    { 0x4B, 0x6E, 0x10, 0x01,  0xFF, 0, 0, 0, 0xFF, 0, 0, 0 };
197 #endif
198 
199 
200 static const struct usb_device_id id_table[] = {
201 	/* the same device id seems to be used by all
202 	   usb enabled GPS devices */
203 	{ USB_DEVICE(GARMIN_VENDOR_ID, 3) },
204 	{ }					/* Terminating entry */
205 };
206 MODULE_DEVICE_TABLE(usb, id_table);
207 
208 
209 static inline int getLayerId(const __u8 *usbPacket)
210 {
211 	return __le32_to_cpup((__le32 *)(usbPacket));
212 }
213 
214 static inline int getPacketId(const __u8 *usbPacket)
215 {
216 	return __le32_to_cpup((__le32 *)(usbPacket+4));
217 }
218 
219 static inline int getDataLength(const __u8 *usbPacket)
220 {
221 	return __le32_to_cpup((__le32 *)(usbPacket+8));
222 }
223 
224 
225 /*
226  * check if the usb-packet in buf contains an abort-transfer command.
227  * (if yes, all queued data will be dropped)
228  */
229 static inline int isAbortTrfCmnd(const unsigned char *buf)
230 {
231 	if (memcmp(buf, GARMIN_STOP_TRANSFER_REQ,
232 			sizeof(GARMIN_STOP_TRANSFER_REQ)) == 0 ||
233 	    memcmp(buf, GARMIN_STOP_TRANSFER_REQ_V2,
234 			sizeof(GARMIN_STOP_TRANSFER_REQ_V2)) == 0)
235 		return 1;
236 	else
237 		return 0;
238 }
239 
240 
241 
242 static void send_to_tty(struct usb_serial_port *port,
243 			char *data, unsigned int actual_length)
244 {
245 	if (actual_length) {
246 		usb_serial_debug_data(&port->dev, __func__, actual_length, data);
247 		tty_insert_flip_string(&port->port, data, actual_length);
248 		tty_flip_buffer_push(&port->port);
249 	}
250 }
251 
252 
253 /******************************************************************************
254  * packet queue handling
255  ******************************************************************************/
256 
257 /*
258  * queue a received (usb-)packet for later processing
259  */
260 static int pkt_add(struct garmin_data *garmin_data_p,
261 		   unsigned char *data, unsigned int data_length)
262 {
263 	int state = 0;
264 	int result = 0;
265 	unsigned long flags;
266 	struct garmin_packet *pkt;
267 
268 	/* process only packets containing data ... */
269 	if (data_length) {
270 		pkt = kmalloc(struct_size(pkt, data, data_length), GFP_ATOMIC);
271 		if (!pkt)
272 			return 0;
273 
274 		pkt->size = data_length;
275 		memcpy(pkt->data, data, data_length);
276 
277 		spin_lock_irqsave(&garmin_data_p->lock, flags);
278 		garmin_data_p->flags |= FLAGS_QUEUING;
279 		result = list_empty(&garmin_data_p->pktlist);
280 		pkt->seq = garmin_data_p->seq_counter++;
281 		list_add_tail(&pkt->list, &garmin_data_p->pktlist);
282 		state = garmin_data_p->state;
283 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
284 
285 		dev_dbg(&garmin_data_p->port->dev,
286 			"%s - added: pkt: %d - %d bytes\n", __func__,
287 			pkt->seq, data_length);
288 
289 		/* in serial mode, if someone is waiting for data from
290 		   the device, convert and send the next packet to tty. */
291 		if (result && (state == STATE_GSP_WAIT_DATA))
292 			gsp_next_packet(garmin_data_p);
293 	}
294 	return result;
295 }
296 
297 
298 /* get the next pending packet */
299 static struct garmin_packet *pkt_pop(struct garmin_data *garmin_data_p)
300 {
301 	unsigned long flags;
302 	struct garmin_packet *result = NULL;
303 
304 	spin_lock_irqsave(&garmin_data_p->lock, flags);
305 	if (!list_empty(&garmin_data_p->pktlist)) {
306 		result = (struct garmin_packet *)garmin_data_p->pktlist.next;
307 		list_del(&result->list);
308 	}
309 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
310 	return result;
311 }
312 
313 
314 /* free up all queued data */
315 static void pkt_clear(struct garmin_data *garmin_data_p)
316 {
317 	unsigned long flags;
318 	struct garmin_packet *result = NULL;
319 
320 	spin_lock_irqsave(&garmin_data_p->lock, flags);
321 	while (!list_empty(&garmin_data_p->pktlist)) {
322 		result = (struct garmin_packet *)garmin_data_p->pktlist.next;
323 		list_del(&result->list);
324 		kfree(result);
325 	}
326 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
327 }
328 
329 
330 /******************************************************************************
331  * garmin serial protocol handling handling
332  ******************************************************************************/
333 
334 /* send an ack packet back to the tty */
335 static int gsp_send_ack(struct garmin_data *garmin_data_p, __u8 pkt_id)
336 {
337 	__u8 pkt[10];
338 	__u8 cksum = 0;
339 	__u8 *ptr = pkt;
340 	unsigned  l = 0;
341 
342 	dev_dbg(&garmin_data_p->port->dev, "%s - pkt-id: 0x%X.\n", __func__,
343 			pkt_id);
344 
345 	*ptr++ = DLE;
346 	*ptr++ = ACK;
347 	cksum += ACK;
348 
349 	*ptr++ = 2;
350 	cksum += 2;
351 
352 	*ptr++ = pkt_id;
353 	cksum += pkt_id;
354 
355 	if (pkt_id == DLE)
356 		*ptr++ = DLE;
357 
358 	*ptr++ = 0;
359 	*ptr++ = (-cksum) & 0xFF;
360 	*ptr++ = DLE;
361 	*ptr++ = ETX;
362 
363 	l = ptr-pkt;
364 
365 	send_to_tty(garmin_data_p->port, pkt, l);
366 	return 0;
367 }
368 
369 
370 
371 /*
372  * called for a complete packet received from tty layer
373  *
374  * the complete packet (pktid ... cksum) is in garmin_data_p->inbuf starting
375  * at GSP_INITIAL_OFFSET.
376  *
377  * count - number of bytes in the input buffer including space reserved for
378  *         the usb header: GSP_INITIAL_OFFSET + number of bytes in packet
379  *         (including pkt-id, data-length a. cksum)
380  */
381 static int gsp_rec_packet(struct garmin_data *garmin_data_p, int count)
382 {
383 	struct device *dev = &garmin_data_p->port->dev;
384 	unsigned long flags;
385 	const __u8 *recpkt = garmin_data_p->inbuffer+GSP_INITIAL_OFFSET;
386 	__le32 *usbdata = (__le32 *) garmin_data_p->inbuffer;
387 	int cksum = 0;
388 	int n = 0;
389 	int pktid = recpkt[0];
390 	int size = recpkt[1];
391 
392 	usb_serial_debug_data(&garmin_data_p->port->dev, __func__,
393 			      count-GSP_INITIAL_OFFSET, recpkt);
394 
395 	if (size != (count-GSP_INITIAL_OFFSET-3)) {
396 		dev_dbg(dev, "%s - invalid size, expected %d bytes, got %d\n",
397 			__func__, size, (count-GSP_INITIAL_OFFSET-3));
398 		return -EINVPKT;
399 	}
400 
401 	cksum += *recpkt++;
402 	cksum += *recpkt++;
403 
404 	/* sanity check, remove after test ... */
405 	if ((__u8 *)&(usbdata[3]) != recpkt) {
406 		dev_dbg(dev, "%s - ptr mismatch %p - %p\n", __func__,
407 			&(usbdata[4]), recpkt);
408 		return -EINVPKT;
409 	}
410 
411 	while (n < size) {
412 		cksum += *recpkt++;
413 		n++;
414 	}
415 
416 	if (((cksum + *recpkt) & 0xff) != 0) {
417 		dev_dbg(dev, "%s - invalid checksum, expected %02x, got %02x\n",
418 			__func__, -cksum & 0xff, *recpkt);
419 		return -EINVPKT;
420 	}
421 
422 	usbdata[0] = __cpu_to_le32(GARMIN_LAYERID_APPL);
423 	usbdata[1] = __cpu_to_le32(pktid);
424 	usbdata[2] = __cpu_to_le32(size);
425 
426 	garmin_write_bulk(garmin_data_p->port, garmin_data_p->inbuffer,
427 			   GARMIN_PKTHDR_LENGTH+size, 0);
428 
429 	/* if this was an abort-transfer command, flush all
430 	   queued data. */
431 	if (isAbortTrfCmnd(garmin_data_p->inbuffer)) {
432 		spin_lock_irqsave(&garmin_data_p->lock, flags);
433 		garmin_data_p->flags |= FLAGS_DROP_DATA;
434 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
435 		pkt_clear(garmin_data_p);
436 	}
437 
438 	return count;
439 }
440 
441 
442 
443 /*
444  * Called for data received from tty
445  *
446  * buf contains the data read, it may span more than one packet or even
447  * incomplete packets
448  *
449  * input record should be a serial-record, but it may not be complete.
450  * Copy it into our local buffer, until an etx is seen (or an error
451  * occurs).
452  * Once the record is complete, convert into a usb packet and send it
453  * to the bulk pipe, send an ack back to the tty.
454  *
455  * If the input is an ack, just send the last queued packet to the
456  * tty layer.
457  *
458  * if the input is an abort command, drop all queued data.
459  */
460 
461 static int gsp_receive(struct garmin_data *garmin_data_p,
462 		       const unsigned char *buf, int count)
463 {
464 	struct device *dev = &garmin_data_p->port->dev;
465 	unsigned long flags;
466 	int offs = 0;
467 	int ack_or_nak_seen = 0;
468 	__u8 *dest;
469 	int size;
470 	/* dleSeen: set if last byte read was a DLE */
471 	int dleSeen;
472 	/* skip: if set, skip incoming data until possible start of
473 	 *       new packet
474 	 */
475 	int skip;
476 	__u8 data;
477 
478 	spin_lock_irqsave(&garmin_data_p->lock, flags);
479 	dest = garmin_data_p->inbuffer;
480 	size = garmin_data_p->insize;
481 	dleSeen = garmin_data_p->flags & FLAGS_GSP_DLESEEN;
482 	skip = garmin_data_p->flags & FLAGS_GSP_SKIP;
483 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
484 
485 	/* dev_dbg(dev, "%s - dle=%d skip=%d size=%d count=%d\n",
486 		__func__, dleSeen, skip, size, count); */
487 
488 	if (size == 0)
489 		size = GSP_INITIAL_OFFSET;
490 
491 	while (offs < count) {
492 
493 		data = *(buf+offs);
494 		offs++;
495 
496 		if (data == DLE) {
497 			if (skip) { /* start of a new pkt */
498 				skip = 0;
499 				size = GSP_INITIAL_OFFSET;
500 				dleSeen = 1;
501 			} else if (dleSeen) {
502 				dest[size++] = data;
503 				dleSeen = 0;
504 			} else {
505 				dleSeen = 1;
506 			}
507 		} else if (data == ETX) {
508 			if (dleSeen) {
509 				/* packet complete */
510 
511 				data = dest[GSP_INITIAL_OFFSET];
512 
513 				if (data == ACK) {
514 					ack_or_nak_seen = ACK;
515 					dev_dbg(dev, "ACK packet complete.\n");
516 				} else if (data == NAK) {
517 					ack_or_nak_seen = NAK;
518 					dev_dbg(dev, "NAK packet complete.\n");
519 				} else {
520 					dev_dbg(dev, "packet complete - id=0x%X.\n",
521 							data);
522 					gsp_rec_packet(garmin_data_p, size);
523 				}
524 
525 				skip = 1;
526 				size = GSP_INITIAL_OFFSET;
527 				dleSeen = 0;
528 			} else {
529 				dest[size++] = data;
530 			}
531 		} else if (!skip) {
532 
533 			if (dleSeen) {
534 				size = GSP_INITIAL_OFFSET;
535 				dleSeen = 0;
536 			}
537 
538 			dest[size++] = data;
539 		}
540 
541 		if (size >= GPS_IN_BUFSIZ) {
542 			dev_dbg(dev, "%s - packet too large.\n", __func__);
543 			skip = 1;
544 			size = GSP_INITIAL_OFFSET;
545 			dleSeen = 0;
546 		}
547 	}
548 
549 	spin_lock_irqsave(&garmin_data_p->lock, flags);
550 
551 	garmin_data_p->insize = size;
552 
553 	/* copy flags back to structure */
554 	if (skip)
555 		garmin_data_p->flags |= FLAGS_GSP_SKIP;
556 	else
557 		garmin_data_p->flags &= ~FLAGS_GSP_SKIP;
558 
559 	if (dleSeen)
560 		garmin_data_p->flags |= FLAGS_GSP_DLESEEN;
561 	else
562 		garmin_data_p->flags &= ~FLAGS_GSP_DLESEEN;
563 
564 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
565 
566 	if (ack_or_nak_seen) {
567 		if (gsp_next_packet(garmin_data_p) > 0)
568 			garmin_data_p->state = STATE_ACTIVE;
569 		else
570 			garmin_data_p->state = STATE_GSP_WAIT_DATA;
571 	}
572 	return count;
573 }
574 
575 
576 
577 /*
578  * Sends a usb packet to the tty
579  *
580  * Assumes, that all packages and at an usb-packet boundary.
581  *
582  * return <0 on error, 0 if packet is incomplete or > 0 if packet was sent
583  */
584 static int gsp_send(struct garmin_data *garmin_data_p,
585 		    const unsigned char *buf, int count)
586 {
587 	struct device *dev = &garmin_data_p->port->dev;
588 	const unsigned char *src;
589 	unsigned char *dst;
590 	int pktid = 0;
591 	int datalen = 0;
592 	int cksum = 0;
593 	int i = 0;
594 	int k;
595 
596 	dev_dbg(dev, "%s - state %d - %d bytes.\n", __func__,
597 		garmin_data_p->state, count);
598 
599 	k = garmin_data_p->outsize;
600 	if ((k+count) > GPS_OUT_BUFSIZ) {
601 		dev_dbg(dev, "packet too large\n");
602 		garmin_data_p->outsize = 0;
603 		return -4;
604 	}
605 
606 	memcpy(garmin_data_p->outbuffer+k, buf, count);
607 	k += count;
608 	garmin_data_p->outsize = k;
609 
610 	if (k >= GARMIN_PKTHDR_LENGTH) {
611 		pktid  = getPacketId(garmin_data_p->outbuffer);
612 		datalen = getDataLength(garmin_data_p->outbuffer);
613 		i = GARMIN_PKTHDR_LENGTH + datalen;
614 		if (k < i)
615 			return 0;
616 	} else {
617 		return 0;
618 	}
619 
620 	dev_dbg(dev, "%s - %d bytes in buffer, %d bytes in pkt.\n", __func__, k, i);
621 
622 	/* garmin_data_p->outbuffer now contains a complete packet */
623 
624 	usb_serial_debug_data(&garmin_data_p->port->dev, __func__, k,
625 			      garmin_data_p->outbuffer);
626 
627 	garmin_data_p->outsize = 0;
628 
629 	if (getLayerId(garmin_data_p->outbuffer) != GARMIN_LAYERID_APPL) {
630 		dev_dbg(dev, "not an application packet (%d)\n",
631 				getLayerId(garmin_data_p->outbuffer));
632 		return -1;
633 	}
634 
635 	if (pktid > 255) {
636 		dev_dbg(dev, "packet-id %d too large\n", pktid);
637 		return -2;
638 	}
639 
640 	if (datalen > 255) {
641 		dev_dbg(dev, "packet-size %d too large\n", datalen);
642 		return -3;
643 	}
644 
645 	/* the serial protocol should be able to handle this packet */
646 
647 	k = 0;
648 	src = garmin_data_p->outbuffer+GARMIN_PKTHDR_LENGTH;
649 	for (i = 0; i < datalen; i++) {
650 		if (*src++ == DLE)
651 			k++;
652 	}
653 
654 	src = garmin_data_p->outbuffer+GARMIN_PKTHDR_LENGTH;
655 	if (k > (GARMIN_PKTHDR_LENGTH-2)) {
656 		/* can't add stuffing DLEs in place, move data to end
657 		   of buffer ... */
658 		dst = garmin_data_p->outbuffer+GPS_OUT_BUFSIZ-datalen;
659 		memcpy(dst, src, datalen);
660 		src = dst;
661 	}
662 
663 	dst = garmin_data_p->outbuffer;
664 
665 	*dst++ = DLE;
666 	*dst++ = pktid;
667 	cksum += pktid;
668 	*dst++ = datalen;
669 	cksum += datalen;
670 	if (datalen == DLE)
671 		*dst++ = DLE;
672 
673 	for (i = 0; i < datalen; i++) {
674 		__u8 c = *src++;
675 		*dst++ = c;
676 		cksum += c;
677 		if (c == DLE)
678 			*dst++ = DLE;
679 	}
680 
681 	cksum = -cksum & 0xFF;
682 	*dst++ = cksum;
683 	if (cksum == DLE)
684 		*dst++ = DLE;
685 	*dst++ = DLE;
686 	*dst++ = ETX;
687 
688 	i = dst-garmin_data_p->outbuffer;
689 
690 	send_to_tty(garmin_data_p->port, garmin_data_p->outbuffer, i);
691 
692 	garmin_data_p->pkt_id = pktid;
693 	garmin_data_p->state  = STATE_WAIT_TTY_ACK;
694 
695 	return i;
696 }
697 
698 
699 /*
700  * Process the next pending data packet - if there is one
701  */
702 static int gsp_next_packet(struct garmin_data *garmin_data_p)
703 {
704 	int result = 0;
705 	struct garmin_packet *pkt = NULL;
706 
707 	while ((pkt = pkt_pop(garmin_data_p)) != NULL) {
708 		dev_dbg(&garmin_data_p->port->dev, "%s - next pkt: %d\n", __func__, pkt->seq);
709 		result = gsp_send(garmin_data_p, pkt->data, pkt->size);
710 		if (result > 0) {
711 			kfree(pkt);
712 			return result;
713 		}
714 		kfree(pkt);
715 	}
716 	return result;
717 }
718 
719 
720 
721 /******************************************************************************
722  * garmin native mode
723  ******************************************************************************/
724 
725 
726 /*
727  * Called for data received from tty
728  *
729  * The input data is expected to be in garmin usb-packet format.
730  *
731  * buf contains the data read, it may span more than one packet
732  * or even incomplete packets
733  */
734 static int nat_receive(struct garmin_data *garmin_data_p,
735 		       const unsigned char *buf, int count)
736 {
737 	unsigned long flags;
738 	__u8 *dest;
739 	int offs = 0;
740 	int result = count;
741 	int len;
742 
743 	while (offs < count) {
744 		/* if buffer contains header, copy rest of data */
745 		if (garmin_data_p->insize >= GARMIN_PKTHDR_LENGTH)
746 			len = GARMIN_PKTHDR_LENGTH
747 			      +getDataLength(garmin_data_p->inbuffer);
748 		else
749 			len = GARMIN_PKTHDR_LENGTH;
750 
751 		if (len >= GPS_IN_BUFSIZ) {
752 			/* seems to be an invalid packet, ignore rest
753 			   of input */
754 			dev_dbg(&garmin_data_p->port->dev,
755 				"%s - packet size too large: %d\n",
756 				__func__, len);
757 			garmin_data_p->insize = 0;
758 			count = 0;
759 			result = -EINVPKT;
760 		} else {
761 			len -= garmin_data_p->insize;
762 			if (len > (count-offs))
763 				len = (count-offs);
764 			if (len > 0) {
765 				dest = garmin_data_p->inbuffer
766 						+ garmin_data_p->insize;
767 				memcpy(dest, buf+offs, len);
768 				garmin_data_p->insize += len;
769 				offs += len;
770 			}
771 		}
772 
773 		/* do we have a complete packet ? */
774 		if (garmin_data_p->insize >= GARMIN_PKTHDR_LENGTH) {
775 			len = GARMIN_PKTHDR_LENGTH+
776 			   getDataLength(garmin_data_p->inbuffer);
777 			if (garmin_data_p->insize >= len) {
778 				garmin_write_bulk(garmin_data_p->port,
779 						   garmin_data_p->inbuffer,
780 						   len, 0);
781 				garmin_data_p->insize = 0;
782 
783 				/* if this was an abort-transfer command,
784 				   flush all queued data. */
785 				if (isAbortTrfCmnd(garmin_data_p->inbuffer)) {
786 					spin_lock_irqsave(&garmin_data_p->lock,
787 									flags);
788 					garmin_data_p->flags |= FLAGS_DROP_DATA;
789 					spin_unlock_irqrestore(
790 						&garmin_data_p->lock, flags);
791 					pkt_clear(garmin_data_p);
792 				}
793 			}
794 		}
795 	}
796 	return result;
797 }
798 
799 
800 /******************************************************************************
801  * private packets
802  ******************************************************************************/
803 
804 static void priv_status_resp(struct usb_serial_port *port)
805 {
806 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
807 	__le32 *pkt = (__le32 *)garmin_data_p->privpkt;
808 
809 	pkt[0] = __cpu_to_le32(GARMIN_LAYERID_PRIVATE);
810 	pkt[1] = __cpu_to_le32(PRIV_PKTID_INFO_RESP);
811 	pkt[2] = __cpu_to_le32(12);
812 	pkt[3] = __cpu_to_le32(VERSION_MAJOR << 16 | VERSION_MINOR);
813 	pkt[4] = __cpu_to_le32(garmin_data_p->mode);
814 	pkt[5] = __cpu_to_le32(garmin_data_p->serial_num);
815 
816 	send_to_tty(port, (__u8 *)pkt, 6 * 4);
817 }
818 
819 
820 /******************************************************************************
821  * Garmin specific driver functions
822  ******************************************************************************/
823 
824 static int process_resetdev_request(struct usb_serial_port *port)
825 {
826 	unsigned long flags;
827 	int status;
828 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
829 
830 	spin_lock_irqsave(&garmin_data_p->lock, flags);
831 	garmin_data_p->flags &= ~(CLEAR_HALT_REQUIRED);
832 	garmin_data_p->state = STATE_RESET;
833 	garmin_data_p->serial_num = 0;
834 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
835 
836 	usb_kill_urb(port->interrupt_in_urb);
837 	dev_dbg(&port->dev, "%s - usb_reset_device\n", __func__);
838 	status = usb_reset_device(port->serial->dev);
839 	if (status)
840 		dev_dbg(&port->dev, "%s - usb_reset_device failed: %d\n",
841 			__func__, status);
842 	return status;
843 }
844 
845 
846 
847 /*
848  * clear all cached data
849  */
850 static int garmin_clear(struct garmin_data *garmin_data_p)
851 {
852 	unsigned long flags;
853 
854 	/* flush all queued data */
855 	pkt_clear(garmin_data_p);
856 
857 	spin_lock_irqsave(&garmin_data_p->lock, flags);
858 	garmin_data_p->insize = 0;
859 	garmin_data_p->outsize = 0;
860 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
861 
862 	return 0;
863 }
864 
865 
866 static int garmin_init_session(struct usb_serial_port *port)
867 {
868 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
869 	int status;
870 	int i;
871 
872 	usb_kill_urb(port->interrupt_in_urb);
873 
874 	status = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
875 	if (status) {
876 		dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
877 				status);
878 		return status;
879 	}
880 
881 	/*
882 	 * using the initialization method from gpsbabel. See comments in
883 	 * gpsbabel/jeeps/gpslibusb.c gusb_reset_toggles()
884 	 */
885 	dev_dbg(&port->dev, "%s - starting session ...\n", __func__);
886 	garmin_data_p->state = STATE_ACTIVE;
887 
888 	for (i = 0; i < 3; i++) {
889 		status = garmin_write_bulk(port, GARMIN_START_SESSION_REQ,
890 				sizeof(GARMIN_START_SESSION_REQ), 0);
891 		if (status < 0)
892 			goto err_kill_urbs;
893 	}
894 
895 	return 0;
896 
897 err_kill_urbs:
898 	usb_kill_anchored_urbs(&garmin_data_p->write_urbs);
899 	usb_kill_urb(port->interrupt_in_urb);
900 
901 	return status;
902 }
903 
904 
905 
906 static int garmin_open(struct tty_struct *tty, struct usb_serial_port *port)
907 {
908 	unsigned long flags;
909 	int status = 0;
910 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
911 
912 	spin_lock_irqsave(&garmin_data_p->lock, flags);
913 	garmin_data_p->mode  = initial_mode;
914 	garmin_data_p->count = 0;
915 	garmin_data_p->flags &= FLAGS_SESSION_REPLY1_SEEN;
916 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
917 
918 	/* shutdown any bulk reads that might be going on */
919 	usb_kill_urb(port->read_urb);
920 
921 	if (garmin_data_p->state == STATE_RESET)
922 		status = garmin_init_session(port);
923 
924 	garmin_data_p->state = STATE_ACTIVE;
925 	return status;
926 }
927 
928 
929 static void garmin_close(struct usb_serial_port *port)
930 {
931 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
932 
933 	dev_dbg(&port->dev, "%s - mode=%d state=%d flags=0x%X\n",
934 		__func__, garmin_data_p->mode, garmin_data_p->state,
935 		garmin_data_p->flags);
936 
937 	garmin_clear(garmin_data_p);
938 
939 	/* shutdown our urbs */
940 	usb_kill_urb(port->read_urb);
941 	usb_kill_anchored_urbs(&garmin_data_p->write_urbs);
942 
943 	/* keep reset state so we know that we must start a new session */
944 	if (garmin_data_p->state != STATE_RESET)
945 		garmin_data_p->state = STATE_DISCONNECTED;
946 }
947 
948 
949 static void garmin_write_bulk_callback(struct urb *urb)
950 {
951 	struct usb_serial_port *port = urb->context;
952 
953 	if (port) {
954 		struct garmin_data *garmin_data_p =
955 					usb_get_serial_port_data(port);
956 
957 		if (getLayerId(urb->transfer_buffer) == GARMIN_LAYERID_APPL) {
958 
959 			if (garmin_data_p->mode == MODE_GARMIN_SERIAL) {
960 				gsp_send_ack(garmin_data_p,
961 					((__u8 *)urb->transfer_buffer)[4]);
962 			}
963 		}
964 		usb_serial_port_softint(port);
965 	}
966 
967 	/* Ignore errors that resulted from garmin_write_bulk with
968 	   dismiss_ack = 1 */
969 
970 	/* free up the transfer buffer, as usb_free_urb() does not do this */
971 	kfree(urb->transfer_buffer);
972 }
973 
974 
975 static int garmin_write_bulk(struct usb_serial_port *port,
976 			      const unsigned char *buf, int count,
977 			      int dismiss_ack)
978 {
979 	unsigned long flags;
980 	struct usb_serial *serial = port->serial;
981 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
982 	struct urb *urb;
983 	unsigned char *buffer;
984 	int status;
985 
986 	spin_lock_irqsave(&garmin_data_p->lock, flags);
987 	garmin_data_p->flags &= ~FLAGS_DROP_DATA;
988 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
989 
990 	buffer = kmemdup(buf, count, GFP_ATOMIC);
991 	if (!buffer)
992 		return -ENOMEM;
993 
994 	urb = usb_alloc_urb(0, GFP_ATOMIC);
995 	if (!urb) {
996 		kfree(buffer);
997 		return -ENOMEM;
998 	}
999 
1000 	usb_serial_debug_data(&port->dev, __func__, count, buffer);
1001 
1002 	usb_fill_bulk_urb(urb, serial->dev,
1003 				usb_sndbulkpipe(serial->dev,
1004 					port->bulk_out_endpointAddress),
1005 				buffer, count,
1006 				garmin_write_bulk_callback,
1007 				dismiss_ack ? NULL : port);
1008 	urb->transfer_flags |= URB_ZERO_PACKET;
1009 
1010 	if (getLayerId(buffer) == GARMIN_LAYERID_APPL) {
1011 
1012 		spin_lock_irqsave(&garmin_data_p->lock, flags);
1013 		garmin_data_p->flags |= APP_REQ_SEEN;
1014 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
1015 
1016 		if (garmin_data_p->mode == MODE_GARMIN_SERIAL)  {
1017 			pkt_clear(garmin_data_p);
1018 			garmin_data_p->state = STATE_GSP_WAIT_DATA;
1019 		}
1020 	}
1021 
1022 	/* send it down the pipe */
1023 	usb_anchor_urb(urb, &garmin_data_p->write_urbs);
1024 	status = usb_submit_urb(urb, GFP_ATOMIC);
1025 	if (status) {
1026 		dev_err(&port->dev,
1027 		   "%s - usb_submit_urb(write bulk) failed with status = %d\n",
1028 				__func__, status);
1029 		count = status;
1030 		usb_unanchor_urb(urb);
1031 		kfree(buffer);
1032 	}
1033 
1034 	/* we are done with this urb, so let the host driver
1035 	 * really free it when it is finished with it */
1036 	usb_free_urb(urb);
1037 
1038 	return count;
1039 }
1040 
1041 static int garmin_write(struct tty_struct *tty, struct usb_serial_port *port,
1042 					 const unsigned char *buf, int count)
1043 {
1044 	struct device *dev = &port->dev;
1045 	int pktid, pktsiz, len;
1046 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
1047 	__le32 *privpkt = (__le32 *)garmin_data_p->privpkt;
1048 
1049 	usb_serial_debug_data(dev, __func__, count, buf);
1050 
1051 	if (garmin_data_p->state == STATE_RESET)
1052 		return -EIO;
1053 
1054 	/* check for our private packets */
1055 	if (count >= GARMIN_PKTHDR_LENGTH) {
1056 		len = PRIVPKTSIZ;
1057 		if (count < len)
1058 			len = count;
1059 
1060 		memcpy(garmin_data_p->privpkt, buf, len);
1061 
1062 		pktsiz = getDataLength(garmin_data_p->privpkt);
1063 		pktid  = getPacketId(garmin_data_p->privpkt);
1064 
1065 		if (count == (GARMIN_PKTHDR_LENGTH + pktsiz) &&
1066 				getLayerId(garmin_data_p->privpkt) ==
1067 						GARMIN_LAYERID_PRIVATE) {
1068 
1069 			dev_dbg(dev, "%s - processing private request %d\n",
1070 				__func__, pktid);
1071 
1072 			/* drop all unfinished transfers */
1073 			garmin_clear(garmin_data_p);
1074 
1075 			switch (pktid) {
1076 			case PRIV_PKTID_SET_MODE:
1077 				if (pktsiz != 4)
1078 					return -EINVPKT;
1079 				garmin_data_p->mode = __le32_to_cpu(privpkt[3]);
1080 				dev_dbg(dev, "%s - mode set to %d\n",
1081 					__func__, garmin_data_p->mode);
1082 				break;
1083 
1084 			case PRIV_PKTID_INFO_REQ:
1085 				priv_status_resp(port);
1086 				break;
1087 
1088 			case PRIV_PKTID_RESET_REQ:
1089 				process_resetdev_request(port);
1090 				break;
1091 
1092 			case PRIV_PKTID_SET_DEF_MODE:
1093 				if (pktsiz != 4)
1094 					return -EINVPKT;
1095 				initial_mode = __le32_to_cpu(privpkt[3]);
1096 				dev_dbg(dev, "%s - initial_mode set to %d\n",
1097 					__func__,
1098 					garmin_data_p->mode);
1099 				break;
1100 			}
1101 			return count;
1102 		}
1103 	}
1104 
1105 	if (garmin_data_p->mode == MODE_GARMIN_SERIAL) {
1106 		return gsp_receive(garmin_data_p, buf, count);
1107 	} else {	/* MODE_NATIVE */
1108 		return nat_receive(garmin_data_p, buf, count);
1109 	}
1110 }
1111 
1112 
1113 static unsigned int garmin_write_room(struct tty_struct *tty)
1114 {
1115 	struct usb_serial_port *port = tty->driver_data;
1116 	/*
1117 	 * Report back the bytes currently available in the output buffer.
1118 	 */
1119 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
1120 	return GPS_OUT_BUFSIZ-garmin_data_p->outsize;
1121 }
1122 
1123 
1124 static void garmin_read_process(struct garmin_data *garmin_data_p,
1125 				 unsigned char *data, unsigned data_length,
1126 				 int bulk_data)
1127 {
1128 	unsigned long flags;
1129 
1130 	if (garmin_data_p->flags & FLAGS_DROP_DATA) {
1131 		/* abort-transfer cmd is active */
1132 		dev_dbg(&garmin_data_p->port->dev, "%s - pkt dropped\n", __func__);
1133 	} else if (garmin_data_p->state != STATE_DISCONNECTED &&
1134 		garmin_data_p->state != STATE_RESET) {
1135 
1136 		/* if throttling is active or postprecessing is required
1137 		   put the received data in the input queue, otherwise
1138 		   send it directly to the tty port */
1139 		if (garmin_data_p->flags & FLAGS_QUEUING) {
1140 			pkt_add(garmin_data_p, data, data_length);
1141 		} else if (bulk_data || (data_length >= sizeof(u32) &&
1142 				getLayerId(data) == GARMIN_LAYERID_APPL)) {
1143 
1144 			spin_lock_irqsave(&garmin_data_p->lock, flags);
1145 			garmin_data_p->flags |= APP_RESP_SEEN;
1146 			spin_unlock_irqrestore(&garmin_data_p->lock, flags);
1147 
1148 			if (garmin_data_p->mode == MODE_GARMIN_SERIAL) {
1149 				pkt_add(garmin_data_p, data, data_length);
1150 			} else {
1151 				send_to_tty(garmin_data_p->port, data,
1152 						data_length);
1153 			}
1154 		}
1155 		/* ignore system layer packets ... */
1156 	}
1157 }
1158 
1159 
1160 static void garmin_read_bulk_callback(struct urb *urb)
1161 {
1162 	unsigned long flags;
1163 	struct usb_serial_port *port = urb->context;
1164 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
1165 	unsigned char *data = urb->transfer_buffer;
1166 	int status = urb->status;
1167 	int retval;
1168 
1169 	if (status) {
1170 		dev_dbg(&urb->dev->dev, "%s - nonzero read bulk status received: %d\n",
1171 			__func__, status);
1172 		return;
1173 	}
1174 
1175 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
1176 
1177 	garmin_read_process(garmin_data_p, data, urb->actual_length, 1);
1178 
1179 	if (urb->actual_length == 0 &&
1180 			(garmin_data_p->flags & FLAGS_BULK_IN_RESTART) != 0) {
1181 		spin_lock_irqsave(&garmin_data_p->lock, flags);
1182 		garmin_data_p->flags &= ~FLAGS_BULK_IN_RESTART;
1183 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
1184 		retval = usb_submit_urb(port->read_urb, GFP_ATOMIC);
1185 		if (retval)
1186 			dev_err(&port->dev,
1187 				"%s - failed resubmitting read urb, error %d\n",
1188 				__func__, retval);
1189 	} else if (urb->actual_length > 0) {
1190 		/* Continue trying to read until nothing more is received  */
1191 		if ((garmin_data_p->flags & FLAGS_THROTTLED) == 0) {
1192 			retval = usb_submit_urb(port->read_urb, GFP_ATOMIC);
1193 			if (retval)
1194 				dev_err(&port->dev,
1195 					"%s - failed resubmitting read urb, error %d\n",
1196 					__func__, retval);
1197 		}
1198 	} else {
1199 		dev_dbg(&port->dev, "%s - end of bulk data\n", __func__);
1200 		spin_lock_irqsave(&garmin_data_p->lock, flags);
1201 		garmin_data_p->flags &= ~FLAGS_BULK_IN_ACTIVE;
1202 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
1203 	}
1204 }
1205 
1206 
1207 static void garmin_read_int_callback(struct urb *urb)
1208 {
1209 	unsigned long flags;
1210 	int retval;
1211 	struct usb_serial_port *port = urb->context;
1212 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
1213 	unsigned char *data = urb->transfer_buffer;
1214 	int status = urb->status;
1215 
1216 	switch (status) {
1217 	case 0:
1218 		/* success */
1219 		break;
1220 	case -ECONNRESET:
1221 	case -ENOENT:
1222 	case -ESHUTDOWN:
1223 		/* this urb is terminated, clean up */
1224 		dev_dbg(&urb->dev->dev, "%s - urb shutting down with status: %d\n",
1225 			__func__, status);
1226 		return;
1227 	default:
1228 		dev_dbg(&urb->dev->dev, "%s - nonzero urb status received: %d\n",
1229 			__func__, status);
1230 		return;
1231 	}
1232 
1233 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length,
1234 			      urb->transfer_buffer);
1235 
1236 	if (urb->actual_length == sizeof(GARMIN_BULK_IN_AVAIL_REPLY) &&
1237 		memcmp(data, GARMIN_BULK_IN_AVAIL_REPLY,
1238 				sizeof(GARMIN_BULK_IN_AVAIL_REPLY)) == 0) {
1239 
1240 		dev_dbg(&port->dev, "%s - bulk data available.\n", __func__);
1241 
1242 		if ((garmin_data_p->flags & FLAGS_BULK_IN_ACTIVE) == 0) {
1243 
1244 			/* bulk data available */
1245 			retval = usb_submit_urb(port->read_urb, GFP_ATOMIC);
1246 			if (retval) {
1247 				dev_err(&port->dev,
1248 				 "%s - failed submitting read urb, error %d\n",
1249 							__func__, retval);
1250 			} else {
1251 				spin_lock_irqsave(&garmin_data_p->lock, flags);
1252 				garmin_data_p->flags |= FLAGS_BULK_IN_ACTIVE;
1253 				spin_unlock_irqrestore(&garmin_data_p->lock,
1254 									flags);
1255 			}
1256 		} else {
1257 			/* bulk-in transfer still active */
1258 			spin_lock_irqsave(&garmin_data_p->lock, flags);
1259 			garmin_data_p->flags |= FLAGS_BULK_IN_RESTART;
1260 			spin_unlock_irqrestore(&garmin_data_p->lock, flags);
1261 		}
1262 
1263 	} else if (urb->actual_length == (4+sizeof(GARMIN_START_SESSION_REPLY))
1264 			 && memcmp(data, GARMIN_START_SESSION_REPLY,
1265 				 sizeof(GARMIN_START_SESSION_REPLY)) == 0) {
1266 
1267 		spin_lock_irqsave(&garmin_data_p->lock, flags);
1268 		garmin_data_p->flags |= FLAGS_SESSION_REPLY1_SEEN;
1269 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
1270 
1271 		/* save the serial number */
1272 		garmin_data_p->serial_num = __le32_to_cpup(
1273 					(__le32 *)(data+GARMIN_PKTHDR_LENGTH));
1274 
1275 		dev_dbg(&port->dev, "%s - start-of-session reply seen - serial %u.\n",
1276 			__func__, garmin_data_p->serial_num);
1277 	}
1278 
1279 	garmin_read_process(garmin_data_p, data, urb->actual_length, 0);
1280 
1281 	retval = usb_submit_urb(urb, GFP_ATOMIC);
1282 	if (retval)
1283 		dev_err(&urb->dev->dev,
1284 			"%s - Error %d submitting interrupt urb\n",
1285 			__func__, retval);
1286 }
1287 
1288 
1289 /*
1290  * Sends the next queued packt to the tty port (garmin native mode only)
1291  * and then sets a timer to call itself again until all queued data
1292  * is sent.
1293  */
1294 static int garmin_flush_queue(struct garmin_data *garmin_data_p)
1295 {
1296 	unsigned long flags;
1297 	struct garmin_packet *pkt;
1298 
1299 	if ((garmin_data_p->flags & FLAGS_THROTTLED) == 0) {
1300 		pkt = pkt_pop(garmin_data_p);
1301 		if (pkt != NULL) {
1302 			send_to_tty(garmin_data_p->port, pkt->data, pkt->size);
1303 			kfree(pkt);
1304 			mod_timer(&garmin_data_p->timer, (1)+jiffies);
1305 
1306 		} else {
1307 			spin_lock_irqsave(&garmin_data_p->lock, flags);
1308 			garmin_data_p->flags &= ~FLAGS_QUEUING;
1309 			spin_unlock_irqrestore(&garmin_data_p->lock, flags);
1310 		}
1311 	}
1312 	return 0;
1313 }
1314 
1315 
1316 static void garmin_throttle(struct tty_struct *tty)
1317 {
1318 	struct usb_serial_port *port = tty->driver_data;
1319 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
1320 
1321 	/* set flag, data received will be put into a queue
1322 	   for later processing */
1323 	spin_lock_irq(&garmin_data_p->lock);
1324 	garmin_data_p->flags |= FLAGS_QUEUING|FLAGS_THROTTLED;
1325 	spin_unlock_irq(&garmin_data_p->lock);
1326 }
1327 
1328 
1329 static void garmin_unthrottle(struct tty_struct *tty)
1330 {
1331 	struct usb_serial_port *port = tty->driver_data;
1332 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
1333 	int status;
1334 
1335 	spin_lock_irq(&garmin_data_p->lock);
1336 	garmin_data_p->flags &= ~FLAGS_THROTTLED;
1337 	spin_unlock_irq(&garmin_data_p->lock);
1338 
1339 	/* in native mode send queued data to tty, in
1340 	   serial mode nothing needs to be done here */
1341 	if (garmin_data_p->mode == MODE_NATIVE)
1342 		garmin_flush_queue(garmin_data_p);
1343 
1344 	if ((garmin_data_p->flags & FLAGS_BULK_IN_ACTIVE) != 0) {
1345 		status = usb_submit_urb(port->read_urb, GFP_KERNEL);
1346 		if (status)
1347 			dev_err(&port->dev,
1348 				"%s - failed resubmitting read urb, error %d\n",
1349 				__func__, status);
1350 	}
1351 }
1352 
1353 /*
1354  * The timer is currently only used to send queued packets to
1355  * the tty in cases where the protocol provides no own handshaking
1356  * to initiate the transfer.
1357  */
1358 static void timeout_handler(struct timer_list *t)
1359 {
1360 	struct garmin_data *garmin_data_p = from_timer(garmin_data_p, t, timer);
1361 
1362 	/* send the next queued packet to the tty port */
1363 	if (garmin_data_p->mode == MODE_NATIVE)
1364 		if (garmin_data_p->flags & FLAGS_QUEUING)
1365 			garmin_flush_queue(garmin_data_p);
1366 }
1367 
1368 
1369 
1370 static int garmin_port_probe(struct usb_serial_port *port)
1371 {
1372 	int status;
1373 	struct garmin_data *garmin_data_p;
1374 
1375 	garmin_data_p = kzalloc(sizeof(struct garmin_data), GFP_KERNEL);
1376 	if (!garmin_data_p)
1377 		return -ENOMEM;
1378 
1379 	timer_setup(&garmin_data_p->timer, timeout_handler, 0);
1380 	spin_lock_init(&garmin_data_p->lock);
1381 	INIT_LIST_HEAD(&garmin_data_p->pktlist);
1382 	garmin_data_p->port = port;
1383 	garmin_data_p->state = 0;
1384 	garmin_data_p->flags = 0;
1385 	garmin_data_p->count = 0;
1386 	init_usb_anchor(&garmin_data_p->write_urbs);
1387 	usb_set_serial_port_data(port, garmin_data_p);
1388 
1389 	status = garmin_init_session(port);
1390 	if (status)
1391 		goto err_free;
1392 
1393 	return 0;
1394 err_free:
1395 	kfree(garmin_data_p);
1396 
1397 	return status;
1398 }
1399 
1400 
1401 static void garmin_port_remove(struct usb_serial_port *port)
1402 {
1403 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
1404 
1405 	usb_kill_anchored_urbs(&garmin_data_p->write_urbs);
1406 	usb_kill_urb(port->interrupt_in_urb);
1407 	timer_shutdown_sync(&garmin_data_p->timer);
1408 	kfree(garmin_data_p);
1409 }
1410 
1411 
1412 /* All of the device info needed */
1413 static struct usb_serial_driver garmin_device = {
1414 	.driver = {
1415 		.owner       = THIS_MODULE,
1416 		.name        = "garmin_gps",
1417 	},
1418 	.description         = "Garmin GPS usb/tty",
1419 	.id_table            = id_table,
1420 	.num_ports           = 1,
1421 	.open                = garmin_open,
1422 	.close               = garmin_close,
1423 	.throttle            = garmin_throttle,
1424 	.unthrottle          = garmin_unthrottle,
1425 	.port_probe		= garmin_port_probe,
1426 	.port_remove		= garmin_port_remove,
1427 	.write               = garmin_write,
1428 	.write_room          = garmin_write_room,
1429 	.write_bulk_callback = garmin_write_bulk_callback,
1430 	.read_bulk_callback  = garmin_read_bulk_callback,
1431 	.read_int_callback   = garmin_read_int_callback,
1432 };
1433 
1434 static struct usb_serial_driver * const serial_drivers[] = {
1435 	&garmin_device, NULL
1436 };
1437 
1438 module_usb_serial_driver(serial_drivers, id_table);
1439 
1440 MODULE_AUTHOR(DRIVER_AUTHOR);
1441 MODULE_DESCRIPTION(DRIVER_DESC);
1442 MODULE_LICENSE("GPL");
1443 
1444 module_param(initial_mode, int, 0444);
1445 MODULE_PARM_DESC(initial_mode, "Initial mode");
1446