xref: /linux/drivers/usb/serial/garmin_gps.c (revision 96ac6d435100450f0565708d9b885ea2a7400e0a)
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[1];
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_APP_LAYER_REPLY[]
183 	= { 0x14, 0, 0, 0 };
184 static unsigned char const GARMIN_START_PVT_REQ[]
185 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 49, 0 };
186 static unsigned char const GARMIN_STOP_PVT_REQ[]
187 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 50, 0 };
188 static unsigned char const GARMIN_STOP_TRANSFER_REQ[]
189 	= { 20, 0, 0, 0,  10, 0, 0, 0, 2, 0, 0, 0, 0, 0 };
190 static unsigned char const GARMIN_STOP_TRANSFER_REQ_V2[]
191 	= { 20, 0, 0, 0,  10, 0, 0, 0, 1, 0, 0, 0, 0 };
192 static unsigned char const PRIVATE_REQ[]
193 	=    { 0x4B, 0x6E, 0x10, 0x01,  0xFF, 0, 0, 0, 0xFF, 0, 0, 0 };
194 
195 
196 
197 static const struct usb_device_id id_table[] = {
198 	/* the same device id seems to be used by all
199 	   usb enabled GPS devices */
200 	{ USB_DEVICE(GARMIN_VENDOR_ID, 3) },
201 	{ }					/* Terminating entry */
202 };
203 MODULE_DEVICE_TABLE(usb, id_table);
204 
205 
206 static inline int getLayerId(const __u8 *usbPacket)
207 {
208 	return __le32_to_cpup((__le32 *)(usbPacket));
209 }
210 
211 static inline int getPacketId(const __u8 *usbPacket)
212 {
213 	return __le32_to_cpup((__le32 *)(usbPacket+4));
214 }
215 
216 static inline int getDataLength(const __u8 *usbPacket)
217 {
218 	return __le32_to_cpup((__le32 *)(usbPacket+8));
219 }
220 
221 
222 /*
223  * check if the usb-packet in buf contains an abort-transfer command.
224  * (if yes, all queued data will be dropped)
225  */
226 static inline int isAbortTrfCmnd(const unsigned char *buf)
227 {
228 	if (memcmp(buf, GARMIN_STOP_TRANSFER_REQ,
229 			sizeof(GARMIN_STOP_TRANSFER_REQ)) == 0 ||
230 	    memcmp(buf, GARMIN_STOP_TRANSFER_REQ_V2,
231 			sizeof(GARMIN_STOP_TRANSFER_REQ_V2)) == 0)
232 		return 1;
233 	else
234 		return 0;
235 }
236 
237 
238 
239 static void send_to_tty(struct usb_serial_port *port,
240 			char *data, unsigned int actual_length)
241 {
242 	if (actual_length) {
243 		usb_serial_debug_data(&port->dev, __func__, actual_length, data);
244 		tty_insert_flip_string(&port->port, data, actual_length);
245 		tty_flip_buffer_push(&port->port);
246 	}
247 }
248 
249 
250 /******************************************************************************
251  * packet queue handling
252  ******************************************************************************/
253 
254 /*
255  * queue a received (usb-)packet for later processing
256  */
257 static int pkt_add(struct garmin_data *garmin_data_p,
258 		   unsigned char *data, unsigned int data_length)
259 {
260 	int state = 0;
261 	int result = 0;
262 	unsigned long flags;
263 	struct garmin_packet *pkt;
264 
265 	/* process only packets containing data ... */
266 	if (data_length) {
267 		pkt = kmalloc(sizeof(struct garmin_packet)+data_length,
268 								GFP_ATOMIC);
269 		if (!pkt)
270 			return 0;
271 
272 		pkt->size = data_length;
273 		memcpy(pkt->data, data, data_length);
274 
275 		spin_lock_irqsave(&garmin_data_p->lock, flags);
276 		garmin_data_p->flags |= FLAGS_QUEUING;
277 		result = list_empty(&garmin_data_p->pktlist);
278 		pkt->seq = garmin_data_p->seq_counter++;
279 		list_add_tail(&pkt->list, &garmin_data_p->pktlist);
280 		state = garmin_data_p->state;
281 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
282 
283 		dev_dbg(&garmin_data_p->port->dev,
284 			"%s - added: pkt: %d - %d bytes\n", __func__,
285 			pkt->seq, data_length);
286 
287 		/* in serial mode, if someone is waiting for data from
288 		   the device, convert and send the next packet to tty. */
289 		if (result && (state == STATE_GSP_WAIT_DATA))
290 			gsp_next_packet(garmin_data_p);
291 	}
292 	return result;
293 }
294 
295 
296 /* get the next pending packet */
297 static struct garmin_packet *pkt_pop(struct garmin_data *garmin_data_p)
298 {
299 	unsigned long flags;
300 	struct garmin_packet *result = NULL;
301 
302 	spin_lock_irqsave(&garmin_data_p->lock, flags);
303 	if (!list_empty(&garmin_data_p->pktlist)) {
304 		result = (struct garmin_packet *)garmin_data_p->pktlist.next;
305 		list_del(&result->list);
306 	}
307 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
308 	return result;
309 }
310 
311 
312 /* free up all queued data */
313 static void pkt_clear(struct garmin_data *garmin_data_p)
314 {
315 	unsigned long flags;
316 	struct garmin_packet *result = NULL;
317 
318 	spin_lock_irqsave(&garmin_data_p->lock, flags);
319 	while (!list_empty(&garmin_data_p->pktlist)) {
320 		result = (struct garmin_packet *)garmin_data_p->pktlist.next;
321 		list_del(&result->list);
322 		kfree(result);
323 	}
324 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
325 }
326 
327 
328 /******************************************************************************
329  * garmin serial protocol handling handling
330  ******************************************************************************/
331 
332 /* send an ack packet back to the tty */
333 static int gsp_send_ack(struct garmin_data *garmin_data_p, __u8 pkt_id)
334 {
335 	__u8 pkt[10];
336 	__u8 cksum = 0;
337 	__u8 *ptr = pkt;
338 	unsigned  l = 0;
339 
340 	dev_dbg(&garmin_data_p->port->dev, "%s - pkt-id: 0x%X.\n", __func__,
341 			pkt_id);
342 
343 	*ptr++ = DLE;
344 	*ptr++ = ACK;
345 	cksum += ACK;
346 
347 	*ptr++ = 2;
348 	cksum += 2;
349 
350 	*ptr++ = pkt_id;
351 	cksum += pkt_id;
352 
353 	if (pkt_id == DLE)
354 		*ptr++ = DLE;
355 
356 	*ptr++ = 0;
357 	*ptr++ = (-cksum) & 0xFF;
358 	*ptr++ = DLE;
359 	*ptr++ = ETX;
360 
361 	l = ptr-pkt;
362 
363 	send_to_tty(garmin_data_p->port, pkt, l);
364 	return 0;
365 }
366 
367 
368 
369 /*
370  * called for a complete packet received from tty layer
371  *
372  * the complete packet (pktid ... cksum) is in garmin_data_p->inbuf starting
373  * at GSP_INITIAL_OFFSET.
374  *
375  * count - number of bytes in the input buffer including space reserved for
376  *         the usb header: GSP_INITIAL_OFFSET + number of bytes in packet
377  *         (including pkt-id, data-length a. cksum)
378  */
379 static int gsp_rec_packet(struct garmin_data *garmin_data_p, int count)
380 {
381 	struct device *dev = &garmin_data_p->port->dev;
382 	unsigned long flags;
383 	const __u8 *recpkt = garmin_data_p->inbuffer+GSP_INITIAL_OFFSET;
384 	__le32 *usbdata = (__le32 *) garmin_data_p->inbuffer;
385 	int cksum = 0;
386 	int n = 0;
387 	int pktid = recpkt[0];
388 	int size = recpkt[1];
389 
390 	usb_serial_debug_data(&garmin_data_p->port->dev, __func__,
391 			      count-GSP_INITIAL_OFFSET, recpkt);
392 
393 	if (size != (count-GSP_INITIAL_OFFSET-3)) {
394 		dev_dbg(dev, "%s - invalid size, expected %d bytes, got %d\n",
395 			__func__, size, (count-GSP_INITIAL_OFFSET-3));
396 		return -EINVPKT;
397 	}
398 
399 	cksum += *recpkt++;
400 	cksum += *recpkt++;
401 
402 	/* sanity check, remove after test ... */
403 	if ((__u8 *)&(usbdata[3]) != recpkt) {
404 		dev_dbg(dev, "%s - ptr mismatch %p - %p\n", __func__,
405 			&(usbdata[4]), recpkt);
406 		return -EINVPKT;
407 	}
408 
409 	while (n < size) {
410 		cksum += *recpkt++;
411 		n++;
412 	}
413 
414 	if (((cksum + *recpkt) & 0xff) != 0) {
415 		dev_dbg(dev, "%s - invalid checksum, expected %02x, got %02x\n",
416 			__func__, -cksum & 0xff, *recpkt);
417 		return -EINVPKT;
418 	}
419 
420 	usbdata[0] = __cpu_to_le32(GARMIN_LAYERID_APPL);
421 	usbdata[1] = __cpu_to_le32(pktid);
422 	usbdata[2] = __cpu_to_le32(size);
423 
424 	garmin_write_bulk(garmin_data_p->port, garmin_data_p->inbuffer,
425 			   GARMIN_PKTHDR_LENGTH+size, 0);
426 
427 	/* if this was an abort-transfer command, flush all
428 	   queued data. */
429 	if (isAbortTrfCmnd(garmin_data_p->inbuffer)) {
430 		spin_lock_irqsave(&garmin_data_p->lock, flags);
431 		garmin_data_p->flags |= FLAGS_DROP_DATA;
432 		spin_unlock_irqrestore(&garmin_data_p->lock, flags);
433 		pkt_clear(garmin_data_p);
434 	}
435 
436 	return count;
437 }
438 
439 
440 
441 /*
442  * Called for data received from tty
443  *
444  * buf contains the data read, it may span more than one packet or even
445  * incomplete packets
446  *
447  * input record should be a serial-record, but it may not be complete.
448  * Copy it into our local buffer, until an etx is seen (or an error
449  * occurs).
450  * Once the record is complete, convert into a usb packet and send it
451  * to the bulk pipe, send an ack back to the tty.
452  *
453  * If the input is an ack, just send the last queued packet to the
454  * tty layer.
455  *
456  * if the input is an abort command, drop all queued data.
457  */
458 
459 static int gsp_receive(struct garmin_data *garmin_data_p,
460 		       const unsigned char *buf, int count)
461 {
462 	struct device *dev = &garmin_data_p->port->dev;
463 	unsigned long flags;
464 	int offs = 0;
465 	int ack_or_nak_seen = 0;
466 	__u8 *dest;
467 	int size;
468 	/* dleSeen: set if last byte read was a DLE */
469 	int dleSeen;
470 	/* skip: if set, skip incoming data until possible start of
471 	 *       new packet
472 	 */
473 	int skip;
474 	__u8 data;
475 
476 	spin_lock_irqsave(&garmin_data_p->lock, flags);
477 	dest = garmin_data_p->inbuffer;
478 	size = garmin_data_p->insize;
479 	dleSeen = garmin_data_p->flags & FLAGS_GSP_DLESEEN;
480 	skip = garmin_data_p->flags & FLAGS_GSP_SKIP;
481 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
482 
483 	/* dev_dbg(dev, "%s - dle=%d skip=%d size=%d count=%d\n",
484 		__func__, dleSeen, skip, size, count); */
485 
486 	if (size == 0)
487 		size = GSP_INITIAL_OFFSET;
488 
489 	while (offs < count) {
490 
491 		data = *(buf+offs);
492 		offs++;
493 
494 		if (data == DLE) {
495 			if (skip) { /* start of a new pkt */
496 				skip = 0;
497 				size = GSP_INITIAL_OFFSET;
498 				dleSeen = 1;
499 			} else if (dleSeen) {
500 				dest[size++] = data;
501 				dleSeen = 0;
502 			} else {
503 				dleSeen = 1;
504 			}
505 		} else if (data == ETX) {
506 			if (dleSeen) {
507 				/* packet complete */
508 
509 				data = dest[GSP_INITIAL_OFFSET];
510 
511 				if (data == ACK) {
512 					ack_or_nak_seen = ACK;
513 					dev_dbg(dev, "ACK packet complete.\n");
514 				} else if (data == NAK) {
515 					ack_or_nak_seen = NAK;
516 					dev_dbg(dev, "NAK packet complete.\n");
517 				} else {
518 					dev_dbg(dev, "packet complete - id=0x%X.\n",
519 							data);
520 					gsp_rec_packet(garmin_data_p, size);
521 				}
522 
523 				skip = 1;
524 				size = GSP_INITIAL_OFFSET;
525 				dleSeen = 0;
526 			} else {
527 				dest[size++] = data;
528 			}
529 		} else if (!skip) {
530 
531 			if (dleSeen) {
532 				size = GSP_INITIAL_OFFSET;
533 				dleSeen = 0;
534 			}
535 
536 			dest[size++] = data;
537 		}
538 
539 		if (size >= GPS_IN_BUFSIZ) {
540 			dev_dbg(dev, "%s - packet too large.\n", __func__);
541 			skip = 1;
542 			size = GSP_INITIAL_OFFSET;
543 			dleSeen = 0;
544 		}
545 	}
546 
547 	spin_lock_irqsave(&garmin_data_p->lock, flags);
548 
549 	garmin_data_p->insize = size;
550 
551 	/* copy flags back to structure */
552 	if (skip)
553 		garmin_data_p->flags |= FLAGS_GSP_SKIP;
554 	else
555 		garmin_data_p->flags &= ~FLAGS_GSP_SKIP;
556 
557 	if (dleSeen)
558 		garmin_data_p->flags |= FLAGS_GSP_DLESEEN;
559 	else
560 		garmin_data_p->flags &= ~FLAGS_GSP_DLESEEN;
561 
562 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
563 
564 	if (ack_or_nak_seen) {
565 		if (gsp_next_packet(garmin_data_p) > 0)
566 			garmin_data_p->state = STATE_ACTIVE;
567 		else
568 			garmin_data_p->state = STATE_GSP_WAIT_DATA;
569 	}
570 	return count;
571 }
572 
573 
574 
575 /*
576  * Sends a usb packet to the tty
577  *
578  * Assumes, that all packages and at an usb-packet boundary.
579  *
580  * return <0 on error, 0 if packet is incomplete or > 0 if packet was sent
581  */
582 static int gsp_send(struct garmin_data *garmin_data_p,
583 		    const unsigned char *buf, int count)
584 {
585 	struct device *dev = &garmin_data_p->port->dev;
586 	const unsigned char *src;
587 	unsigned char *dst;
588 	int pktid = 0;
589 	int datalen = 0;
590 	int cksum = 0;
591 	int i = 0;
592 	int k;
593 
594 	dev_dbg(dev, "%s - state %d - %d bytes.\n", __func__,
595 		garmin_data_p->state, count);
596 
597 	k = garmin_data_p->outsize;
598 	if ((k+count) > GPS_OUT_BUFSIZ) {
599 		dev_dbg(dev, "packet too large\n");
600 		garmin_data_p->outsize = 0;
601 		return -4;
602 	}
603 
604 	memcpy(garmin_data_p->outbuffer+k, buf, count);
605 	k += count;
606 	garmin_data_p->outsize = k;
607 
608 	if (k >= GARMIN_PKTHDR_LENGTH) {
609 		pktid  = getPacketId(garmin_data_p->outbuffer);
610 		datalen = getDataLength(garmin_data_p->outbuffer);
611 		i = GARMIN_PKTHDR_LENGTH + datalen;
612 		if (k < i)
613 			return 0;
614 	} else {
615 		return 0;
616 	}
617 
618 	dev_dbg(dev, "%s - %d bytes in buffer, %d bytes in pkt.\n", __func__, k, i);
619 
620 	/* garmin_data_p->outbuffer now contains a complete packet */
621 
622 	usb_serial_debug_data(&garmin_data_p->port->dev, __func__, k,
623 			      garmin_data_p->outbuffer);
624 
625 	garmin_data_p->outsize = 0;
626 
627 	if (getLayerId(garmin_data_p->outbuffer) != GARMIN_LAYERID_APPL) {
628 		dev_dbg(dev, "not an application packet (%d)\n",
629 				getLayerId(garmin_data_p->outbuffer));
630 		return -1;
631 	}
632 
633 	if (pktid > 255) {
634 		dev_dbg(dev, "packet-id %d too large\n", pktid);
635 		return -2;
636 	}
637 
638 	if (datalen > 255) {
639 		dev_dbg(dev, "packet-size %d too large\n", datalen);
640 		return -3;
641 	}
642 
643 	/* the serial protocol should be able to handle this packet */
644 
645 	k = 0;
646 	src = garmin_data_p->outbuffer+GARMIN_PKTHDR_LENGTH;
647 	for (i = 0; i < datalen; i++) {
648 		if (*src++ == DLE)
649 			k++;
650 	}
651 
652 	src = garmin_data_p->outbuffer+GARMIN_PKTHDR_LENGTH;
653 	if (k > (GARMIN_PKTHDR_LENGTH-2)) {
654 		/* can't add stuffing DLEs in place, move data to end
655 		   of buffer ... */
656 		dst = garmin_data_p->outbuffer+GPS_OUT_BUFSIZ-datalen;
657 		memcpy(dst, src, datalen);
658 		src = dst;
659 	}
660 
661 	dst = garmin_data_p->outbuffer;
662 
663 	*dst++ = DLE;
664 	*dst++ = pktid;
665 	cksum += pktid;
666 	*dst++ = datalen;
667 	cksum += datalen;
668 	if (datalen == DLE)
669 		*dst++ = DLE;
670 
671 	for (i = 0; i < datalen; i++) {
672 		__u8 c = *src++;
673 		*dst++ = c;
674 		cksum += c;
675 		if (c == DLE)
676 			*dst++ = DLE;
677 	}
678 
679 	cksum = -cksum & 0xFF;
680 	*dst++ = cksum;
681 	if (cksum == DLE)
682 		*dst++ = DLE;
683 	*dst++ = DLE;
684 	*dst++ = ETX;
685 
686 	i = dst-garmin_data_p->outbuffer;
687 
688 	send_to_tty(garmin_data_p->port, garmin_data_p->outbuffer, i);
689 
690 	garmin_data_p->pkt_id = pktid;
691 	garmin_data_p->state  = STATE_WAIT_TTY_ACK;
692 
693 	return i;
694 }
695 
696 
697 /*
698  * Process the next pending data packet - if there is one
699  */
700 static int gsp_next_packet(struct garmin_data *garmin_data_p)
701 {
702 	int result = 0;
703 	struct garmin_packet *pkt = NULL;
704 
705 	while ((pkt = pkt_pop(garmin_data_p)) != NULL) {
706 		dev_dbg(&garmin_data_p->port->dev, "%s - next pkt: %d\n", __func__, pkt->seq);
707 		result = gsp_send(garmin_data_p, pkt->data, pkt->size);
708 		if (result > 0) {
709 			kfree(pkt);
710 			return result;
711 		}
712 		kfree(pkt);
713 	}
714 	return result;
715 }
716 
717 
718 
719 /******************************************************************************
720  * garmin native mode
721  ******************************************************************************/
722 
723 
724 /*
725  * Called for data received from tty
726  *
727  * The input data is expected to be in garmin usb-packet format.
728  *
729  * buf contains the data read, it may span more than one packet
730  * or even incomplete packets
731  */
732 static int nat_receive(struct garmin_data *garmin_data_p,
733 		       const unsigned char *buf, int count)
734 {
735 	unsigned long flags;
736 	__u8 *dest;
737 	int offs = 0;
738 	int result = count;
739 	int len;
740 
741 	while (offs < count) {
742 		/* if buffer contains header, copy rest of data */
743 		if (garmin_data_p->insize >= GARMIN_PKTHDR_LENGTH)
744 			len = GARMIN_PKTHDR_LENGTH
745 			      +getDataLength(garmin_data_p->inbuffer);
746 		else
747 			len = GARMIN_PKTHDR_LENGTH;
748 
749 		if (len >= GPS_IN_BUFSIZ) {
750 			/* seems to be an invalid packet, ignore rest
751 			   of input */
752 			dev_dbg(&garmin_data_p->port->dev,
753 				"%s - packet size too large: %d\n",
754 				__func__, len);
755 			garmin_data_p->insize = 0;
756 			count = 0;
757 			result = -EINVPKT;
758 		} else {
759 			len -= garmin_data_p->insize;
760 			if (len > (count-offs))
761 				len = (count-offs);
762 			if (len > 0) {
763 				dest = garmin_data_p->inbuffer
764 						+ garmin_data_p->insize;
765 				memcpy(dest, buf+offs, len);
766 				garmin_data_p->insize += len;
767 				offs += len;
768 			}
769 		}
770 
771 		/* do we have a complete packet ? */
772 		if (garmin_data_p->insize >= GARMIN_PKTHDR_LENGTH) {
773 			len = GARMIN_PKTHDR_LENGTH+
774 			   getDataLength(garmin_data_p->inbuffer);
775 			if (garmin_data_p->insize >= len) {
776 				garmin_write_bulk(garmin_data_p->port,
777 						   garmin_data_p->inbuffer,
778 						   len, 0);
779 				garmin_data_p->insize = 0;
780 
781 				/* if this was an abort-transfer command,
782 				   flush all queued data. */
783 				if (isAbortTrfCmnd(garmin_data_p->inbuffer)) {
784 					spin_lock_irqsave(&garmin_data_p->lock,
785 									flags);
786 					garmin_data_p->flags |= FLAGS_DROP_DATA;
787 					spin_unlock_irqrestore(
788 						&garmin_data_p->lock, flags);
789 					pkt_clear(garmin_data_p);
790 				}
791 			}
792 		}
793 	}
794 	return result;
795 }
796 
797 
798 /******************************************************************************
799  * private packets
800  ******************************************************************************/
801 
802 static void priv_status_resp(struct usb_serial_port *port)
803 {
804 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
805 	__le32 *pkt = (__le32 *)garmin_data_p->privpkt;
806 
807 	pkt[0] = __cpu_to_le32(GARMIN_LAYERID_PRIVATE);
808 	pkt[1] = __cpu_to_le32(PRIV_PKTID_INFO_RESP);
809 	pkt[2] = __cpu_to_le32(12);
810 	pkt[3] = __cpu_to_le32(VERSION_MAJOR << 16 | VERSION_MINOR);
811 	pkt[4] = __cpu_to_le32(garmin_data_p->mode);
812 	pkt[5] = __cpu_to_le32(garmin_data_p->serial_num);
813 
814 	send_to_tty(port, (__u8 *)pkt, 6 * 4);
815 }
816 
817 
818 /******************************************************************************
819  * Garmin specific driver functions
820  ******************************************************************************/
821 
822 static int process_resetdev_request(struct usb_serial_port *port)
823 {
824 	unsigned long flags;
825 	int status;
826 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
827 
828 	spin_lock_irqsave(&garmin_data_p->lock, flags);
829 	garmin_data_p->flags &= ~(CLEAR_HALT_REQUIRED);
830 	garmin_data_p->state = STATE_RESET;
831 	garmin_data_p->serial_num = 0;
832 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
833 
834 	usb_kill_urb(port->interrupt_in_urb);
835 	dev_dbg(&port->dev, "%s - usb_reset_device\n", __func__);
836 	status = usb_reset_device(port->serial->dev);
837 	if (status)
838 		dev_dbg(&port->dev, "%s - usb_reset_device failed: %d\n",
839 			__func__, status);
840 	return status;
841 }
842 
843 
844 
845 /*
846  * clear all cached data
847  */
848 static int garmin_clear(struct garmin_data *garmin_data_p)
849 {
850 	unsigned long flags;
851 
852 	/* flush all queued data */
853 	pkt_clear(garmin_data_p);
854 
855 	spin_lock_irqsave(&garmin_data_p->lock, flags);
856 	garmin_data_p->insize = 0;
857 	garmin_data_p->outsize = 0;
858 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
859 
860 	return 0;
861 }
862 
863 
864 static int garmin_init_session(struct usb_serial_port *port)
865 {
866 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
867 	int status;
868 	int i;
869 
870 	usb_kill_urb(port->interrupt_in_urb);
871 
872 	status = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
873 	if (status) {
874 		dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
875 				status);
876 		return status;
877 	}
878 
879 	/*
880 	 * using the initialization method from gpsbabel. See comments in
881 	 * gpsbabel/jeeps/gpslibusb.c gusb_reset_toggles()
882 	 */
883 	dev_dbg(&port->dev, "%s - starting session ...\n", __func__);
884 	garmin_data_p->state = STATE_ACTIVE;
885 
886 	for (i = 0; i < 3; i++) {
887 		status = garmin_write_bulk(port, GARMIN_START_SESSION_REQ,
888 				sizeof(GARMIN_START_SESSION_REQ), 0);
889 		if (status < 0)
890 			goto err_kill_urbs;
891 	}
892 
893 	return 0;
894 
895 err_kill_urbs:
896 	usb_kill_anchored_urbs(&garmin_data_p->write_urbs);
897 	usb_kill_urb(port->interrupt_in_urb);
898 
899 	return status;
900 }
901 
902 
903 
904 static int garmin_open(struct tty_struct *tty, struct usb_serial_port *port)
905 {
906 	unsigned long flags;
907 	int status = 0;
908 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
909 
910 	spin_lock_irqsave(&garmin_data_p->lock, flags);
911 	garmin_data_p->mode  = initial_mode;
912 	garmin_data_p->count = 0;
913 	garmin_data_p->flags &= FLAGS_SESSION_REPLY1_SEEN;
914 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
915 
916 	/* shutdown any bulk reads that might be going on */
917 	usb_kill_urb(port->read_urb);
918 
919 	if (garmin_data_p->state == STATE_RESET)
920 		status = garmin_init_session(port);
921 
922 	garmin_data_p->state = STATE_ACTIVE;
923 	return status;
924 }
925 
926 
927 static void garmin_close(struct usb_serial_port *port)
928 {
929 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
930 
931 	dev_dbg(&port->dev, "%s - mode=%d state=%d flags=0x%X\n",
932 		__func__, garmin_data_p->mode, garmin_data_p->state,
933 		garmin_data_p->flags);
934 
935 	garmin_clear(garmin_data_p);
936 
937 	/* shutdown our urbs */
938 	usb_kill_urb(port->read_urb);
939 	usb_kill_anchored_urbs(&garmin_data_p->write_urbs);
940 
941 	/* keep reset state so we know that we must start a new session */
942 	if (garmin_data_p->state != STATE_RESET)
943 		garmin_data_p->state = STATE_DISCONNECTED;
944 }
945 
946 
947 static void garmin_write_bulk_callback(struct urb *urb)
948 {
949 	struct usb_serial_port *port = urb->context;
950 
951 	if (port) {
952 		struct garmin_data *garmin_data_p =
953 					usb_get_serial_port_data(port);
954 
955 		if (getLayerId(urb->transfer_buffer) == GARMIN_LAYERID_APPL) {
956 
957 			if (garmin_data_p->mode == MODE_GARMIN_SERIAL) {
958 				gsp_send_ack(garmin_data_p,
959 					((__u8 *)urb->transfer_buffer)[4]);
960 			}
961 		}
962 		usb_serial_port_softint(port);
963 	}
964 
965 	/* Ignore errors that resulted from garmin_write_bulk with
966 	   dismiss_ack = 1 */
967 
968 	/* free up the transfer buffer, as usb_free_urb() does not do this */
969 	kfree(urb->transfer_buffer);
970 }
971 
972 
973 static int garmin_write_bulk(struct usb_serial_port *port,
974 			      const unsigned char *buf, int count,
975 			      int dismiss_ack)
976 {
977 	unsigned long flags;
978 	struct usb_serial *serial = port->serial;
979 	struct garmin_data *garmin_data_p = usb_get_serial_port_data(port);
980 	struct urb *urb;
981 	unsigned char *buffer;
982 	int status;
983 
984 	spin_lock_irqsave(&garmin_data_p->lock, flags);
985 	garmin_data_p->flags &= ~FLAGS_DROP_DATA;
986 	spin_unlock_irqrestore(&garmin_data_p->lock, flags);
987 
988 	buffer = kmalloc(count, GFP_ATOMIC);
989 	if (!buffer)
990 		return -ENOMEM;
991 
992 	urb = usb_alloc_urb(0, GFP_ATOMIC);
993 	if (!urb) {
994 		kfree(buffer);
995 		return -ENOMEM;
996 	}
997 
998 	memcpy(buffer, buf, count);
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 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 ||
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 int 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 	del_timer_sync(&garmin_data_p->timer);
1408 	kfree(garmin_data_p);
1409 	return 0;
1410 }
1411 
1412 
1413 /* All of the device info needed */
1414 static struct usb_serial_driver garmin_device = {
1415 	.driver = {
1416 		.owner       = THIS_MODULE,
1417 		.name        = "garmin_gps",
1418 	},
1419 	.description         = "Garmin GPS usb/tty",
1420 	.id_table            = id_table,
1421 	.num_ports           = 1,
1422 	.open                = garmin_open,
1423 	.close               = garmin_close,
1424 	.throttle            = garmin_throttle,
1425 	.unthrottle          = garmin_unthrottle,
1426 	.port_probe		= garmin_port_probe,
1427 	.port_remove		= garmin_port_remove,
1428 	.write               = garmin_write,
1429 	.write_room          = garmin_write_room,
1430 	.write_bulk_callback = garmin_write_bulk_callback,
1431 	.read_bulk_callback  = garmin_read_bulk_callback,
1432 	.read_int_callback   = garmin_read_int_callback,
1433 };
1434 
1435 static struct usb_serial_driver * const serial_drivers[] = {
1436 	&garmin_device, NULL
1437 };
1438 
1439 module_usb_serial_driver(serial_drivers, id_table);
1440 
1441 MODULE_AUTHOR(DRIVER_AUTHOR);
1442 MODULE_DESCRIPTION(DRIVER_DESC);
1443 MODULE_LICENSE("GPL");
1444 
1445 module_param(initial_mode, int, S_IRUGO);
1446 MODULE_PARM_DESC(initial_mode, "Initial mode");
1447