xref: /openbmc/linux/drivers/usb/serial/oti6858.c (revision 643d1f7f)
1 /*
2  * Ours Technology Inc. OTi-6858 USB to serial adapter driver.
3  *
4  * Copyleft  (C) 2007 Kees Lemmens (adapted for kernel 2.6.20)
5  * Copyright (C) 2006 Tomasz Michal Lukaszewski (FIXME: add e-mail)
6  * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
7  * Copyright (C) 2003 IBM Corp.
8  *
9  * Many thanks to the authors of pl2303 driver: all functions in this file
10  * are heavily based on pl2303 code, buffering code is a 1-to-1 copy.
11  *
12  * Warning! You use this driver on your own risk! The only official
13  * description of this device I have is datasheet from manufacturer,
14  * and it doesn't contain almost any information needed to write a driver.
15  * Almost all knowlegde used while writing this driver was gathered by:
16  *  - analyzing traffic between device and the M$ Windows 2000 driver,
17  *  - trying different bit combinations and checking pin states
18  *    with a voltmeter,
19  *  - receiving malformed frames and producing buffer overflows
20  *    to learn how errors are reported,
21  * So, THIS CODE CAN DESTROY OTi-6858 AND ANY OTHER DEVICES, THAT ARE
22  * CONNECTED TO IT!
23  *
24  * This program is free software; you can redistribute it and/or modify
25  * it under the terms of the GNU General Public License as published by
26  * the Free Software Foundation; either version 2 of the License.
27  *
28  * See Documentation/usb/usb-serial.txt for more information on using this driver
29  *
30  * TODO:
31  *  - implement correct flushing for ioctls and oti6858_close()
32  *  - check how errors (rx overflow, parity error, framing error) are reported
33  *  - implement oti6858_break_ctl()
34  *  - implement more ioctls
35  *  - test/implement flow control
36  *  - allow setting custom baud rates
37  */
38 
39 #include <linux/kernel.h>
40 #include <linux/errno.h>
41 #include <linux/init.h>
42 #include <linux/slab.h>
43 #include <linux/tty.h>
44 #include <linux/tty_driver.h>
45 #include <linux/tty_flip.h>
46 #include <linux/serial.h>
47 #include <linux/module.h>
48 #include <linux/moduleparam.h>
49 #include <linux/spinlock.h>
50 #include <linux/usb.h>
51 #include <linux/usb/serial.h>
52 #include <asm/uaccess.h>
53 #include "oti6858.h"
54 
55 #define OTI6858_DESCRIPTION \
56 	"Ours Technology Inc. OTi-6858 USB to serial adapter driver"
57 #define OTI6858_AUTHOR "Tomasz Michal Lukaszewski <FIXME@FIXME>"
58 #define OTI6858_VERSION "0.1"
59 
60 static struct usb_device_id id_table [] = {
61 	{ USB_DEVICE(OTI6858_VENDOR_ID, OTI6858_PRODUCT_ID) },
62 	{ }
63 };
64 
65 MODULE_DEVICE_TABLE(usb, id_table);
66 
67 static struct usb_driver oti6858_driver = {
68 	.name =		"oti6858",
69 	.probe =	usb_serial_probe,
70 	.disconnect =	usb_serial_disconnect,
71 	.id_table =	id_table,
72 	.no_dynamic_id = 	1,
73 };
74 
75 static int debug;
76 
77 
78 /* buffering code, copied from pl2303 driver */
79 #define PL2303_BUF_SIZE		1024
80 #define PL2303_TMP_BUF_SIZE	1024
81 
82 struct oti6858_buf {
83 	unsigned int	buf_size;
84 	char		*buf_buf;
85 	char		*buf_get;
86 	char		*buf_put;
87 };
88 
89 /* requests */
90 #define	OTI6858_REQ_GET_STATUS		(USB_DIR_IN | USB_TYPE_VENDOR | 0x00)
91 #define	OTI6858_REQ_T_GET_STATUS	0x01
92 
93 #define	OTI6858_REQ_SET_LINE		(USB_DIR_OUT | USB_TYPE_VENDOR | 0x00)
94 #define	OTI6858_REQ_T_SET_LINE		0x00
95 
96 #define	OTI6858_REQ_CHECK_TXBUFF	(USB_DIR_IN | USB_TYPE_VENDOR | 0x01)
97 #define	OTI6858_REQ_T_CHECK_TXBUFF	0x00
98 
99 /* format of the control packet */
100 struct oti6858_control_pkt {
101 	u16	divisor;	/* baud rate = 96000000 / (16 * divisor), LE */
102 #define OTI6858_MAX_BAUD_RATE	3000000
103 	u8	frame_fmt;
104 #define FMT_STOP_BITS_MASK	0xc0
105 #define FMT_STOP_BITS_1		0x00
106 #define FMT_STOP_BITS_2		0x40	/* 1.5 stop bits if FMT_DATA_BITS_5 */
107 #define FMT_PARITY_MASK		0x38
108 #define FMT_PARITY_NONE		0x00
109 #define FMT_PARITY_ODD		0x08
110 #define FMT_PARITY_EVEN		0x18
111 #define FMT_PARITY_MARK		0x28
112 #define FMT_PARITY_SPACE	0x38
113 #define FMT_DATA_BITS_MASK	0x03
114 #define FMT_DATA_BITS_5		0x00
115 #define FMT_DATA_BITS_6		0x01
116 #define FMT_DATA_BITS_7		0x02
117 #define FMT_DATA_BITS_8		0x03
118 	u8	something;	/* always equals 0x43 */
119 	u8	control;	/* settings of flow control lines */
120 #define CONTROL_MASK		0x0c
121 #define CONTROL_DTR_HIGH	0x08
122 #define CONTROL_RTS_HIGH	0x04
123 	u8	tx_status;
124 #define	TX_BUFFER_EMPTIED	0x09
125 	u8	pin_state;
126 #define PIN_MASK		0x3f
127 #define PIN_RTS			0x20	/* output pin */
128 #define PIN_CTS			0x10	/* input pin, active low */
129 #define PIN_DSR			0x08	/* input pin, active low */
130 #define PIN_DTR			0x04	/* output pin */
131 #define PIN_RI			0x02	/* input pin, active low */
132 #define PIN_DCD			0x01	/* input pin, active low */
133 	u8	rx_bytes_avail;		/* number of bytes in rx buffer */;
134 };
135 
136 #define OTI6858_CTRL_PKT_SIZE	sizeof(struct oti6858_control_pkt)
137 #define OTI6858_CTRL_EQUALS_PENDING(a, priv) \
138 	(    ((a)->divisor == (priv)->pending_setup.divisor) \
139 	  && ((a)->control == (priv)->pending_setup.control) \
140 	  && ((a)->frame_fmt == (priv)->pending_setup.frame_fmt) )
141 
142 /* function prototypes */
143 static int oti6858_open(struct usb_serial_port *port, struct file *filp);
144 static void oti6858_close(struct usb_serial_port *port, struct file *filp);
145 static void oti6858_set_termios(struct usb_serial_port *port,
146 				struct ktermios *old);
147 static int oti6858_ioctl(struct usb_serial_port *port, struct file *file,
148 			unsigned int cmd, unsigned long arg);
149 static void oti6858_read_int_callback(struct urb *urb);
150 static void oti6858_read_bulk_callback(struct urb *urb);
151 static void oti6858_write_bulk_callback(struct urb *urb);
152 static int oti6858_write(struct usb_serial_port *port,
153 			const unsigned char *buf, int count);
154 static int oti6858_write_room(struct usb_serial_port *port);
155 static void oti6858_break_ctl(struct usb_serial_port *port, int break_state);
156 static int oti6858_chars_in_buffer(struct usb_serial_port *port);
157 static int oti6858_tiocmget(struct usb_serial_port *port, struct file *file);
158 static int oti6858_tiocmset(struct usb_serial_port *port, struct file *file,
159 				unsigned int set, unsigned int clear);
160 static int oti6858_startup(struct usb_serial *serial);
161 static void oti6858_shutdown(struct usb_serial *serial);
162 
163 /* functions operating on buffers */
164 static struct oti6858_buf *oti6858_buf_alloc(unsigned int size);
165 static void oti6858_buf_free(struct oti6858_buf *pb);
166 static void oti6858_buf_clear(struct oti6858_buf *pb);
167 static unsigned int oti6858_buf_data_avail(struct oti6858_buf *pb);
168 static unsigned int oti6858_buf_space_avail(struct oti6858_buf *pb);
169 static unsigned int oti6858_buf_put(struct oti6858_buf *pb, const char *buf,
170 					unsigned int count);
171 static unsigned int oti6858_buf_get(struct oti6858_buf *pb, char *buf,
172 					unsigned int count);
173 
174 
175 /* device info */
176 static struct usb_serial_driver oti6858_device = {
177 	.driver = {
178 		.owner =	THIS_MODULE,
179 		.name =		"oti6858",
180 	},
181 	.id_table =		id_table,
182 	.num_interrupt_in =	1,
183 	.num_bulk_in =		1,
184 	.num_bulk_out =		1,
185 	.num_ports =		1,
186 	.open =			oti6858_open,
187 	.close =		oti6858_close,
188 	.write =		oti6858_write,
189 	.ioctl =		oti6858_ioctl,
190 	.break_ctl =		oti6858_break_ctl,
191 	.set_termios =		oti6858_set_termios,
192 	.tiocmget =		oti6858_tiocmget,
193 	.tiocmset =		oti6858_tiocmset,
194 	.read_bulk_callback =	oti6858_read_bulk_callback,
195 	.read_int_callback =	oti6858_read_int_callback,
196 	.write_bulk_callback =	oti6858_write_bulk_callback,
197 	.write_room =		oti6858_write_room,
198 	.chars_in_buffer =	oti6858_chars_in_buffer,
199 	.attach =		oti6858_startup,
200 	.shutdown =		oti6858_shutdown,
201 };
202 
203 struct oti6858_private {
204 	spinlock_t lock;
205 
206 	struct oti6858_buf *buf;
207 	struct oti6858_control_pkt status;
208 
209 	struct {
210 		u8 read_urb_in_use;
211 		u8 write_urb_in_use;
212 		u8 termios_initialized;
213 	} flags;
214 	struct delayed_work delayed_write_work;
215 
216 	struct {
217 		u16 divisor;
218 		u8 frame_fmt;
219 		u8 control;
220 	} pending_setup;
221 	u8 transient;
222 	u8 setup_done;
223 	struct delayed_work delayed_setup_work;
224 
225 	wait_queue_head_t intr_wait;
226         struct usb_serial_port *port;   /* USB port with which associated */
227 };
228 
229 #undef dbg
230 /* #define dbg(format, arg...) printk(KERN_INFO "%s: " format "\n", __FILE__, ## arg) */
231 #define dbg(format, arg...) printk(KERN_INFO "" format "\n", ## arg)
232 
233 static void setup_line(struct work_struct *work)
234 {
235 	struct oti6858_private *priv = container_of(work, struct oti6858_private, delayed_setup_work.work);
236 	struct usb_serial_port *port = priv->port;
237 	struct oti6858_control_pkt *new_setup;
238 	unsigned long flags;
239 	int result;
240 
241 	dbg("%s(port = %d)", __FUNCTION__, port->number);
242 
243 	if ((new_setup = kmalloc(OTI6858_CTRL_PKT_SIZE, GFP_KERNEL)) == NULL) {
244 		dev_err(&port->dev, "%s(): out of memory!\n", __FUNCTION__);
245 		/* we will try again */
246 		schedule_delayed_work(&priv->delayed_setup_work, msecs_to_jiffies(2));
247 		return;
248 	}
249 
250 	result = usb_control_msg(port->serial->dev,
251 				usb_rcvctrlpipe(port->serial->dev, 0),
252 				OTI6858_REQ_T_GET_STATUS,
253 				OTI6858_REQ_GET_STATUS,
254 				0, 0,
255 				new_setup, OTI6858_CTRL_PKT_SIZE,
256 				100);
257 
258 	if (result != OTI6858_CTRL_PKT_SIZE) {
259 		dev_err(&port->dev, "%s(): error reading status\n", __FUNCTION__);
260 		kfree(new_setup);
261 		/* we will try again */
262 		schedule_delayed_work(&priv->delayed_setup_work, msecs_to_jiffies(2));
263 		return;
264 	}
265 
266 	spin_lock_irqsave(&priv->lock, flags);
267 	if (!OTI6858_CTRL_EQUALS_PENDING(new_setup, priv)) {
268 		new_setup->divisor = priv->pending_setup.divisor;
269 		new_setup->control = priv->pending_setup.control;
270 		new_setup->frame_fmt = priv->pending_setup.frame_fmt;
271 
272 		spin_unlock_irqrestore(&priv->lock, flags);
273 		result = usb_control_msg(port->serial->dev,
274 					usb_sndctrlpipe(port->serial->dev, 0),
275 					OTI6858_REQ_T_SET_LINE,
276 					OTI6858_REQ_SET_LINE,
277 					0, 0,
278 					new_setup, OTI6858_CTRL_PKT_SIZE,
279 					100);
280 	} else {
281 		spin_unlock_irqrestore(&priv->lock, flags);
282 		result = 0;
283 	}
284 	kfree(new_setup);
285 
286 	spin_lock_irqsave(&priv->lock, flags);
287 	if (result != OTI6858_CTRL_PKT_SIZE)
288 		priv->transient = 0;
289 	priv->setup_done = 1;
290 	spin_unlock_irqrestore(&priv->lock, flags);
291 
292 	dbg("%s(): submitting interrupt urb", __FUNCTION__);
293 	port->interrupt_in_urb->dev = port->serial->dev;
294 	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
295 	if (result != 0) {
296 		dev_err(&port->dev, "%s(): usb_submit_urb() failed"
297 				" with error %d\n", __FUNCTION__, result);
298 	}
299 }
300 
301 void send_data(struct work_struct *work)
302 {
303 	struct oti6858_private *priv = container_of(work, struct oti6858_private, delayed_write_work.work);
304 	struct usb_serial_port *port = priv->port;
305 	int count = 0, result;
306 	unsigned long flags;
307 	unsigned char allow;
308 
309 	dbg("%s(port = %d)", __FUNCTION__, port->number);
310 
311 	spin_lock_irqsave(&priv->lock, flags);
312 	if (priv->flags.write_urb_in_use) {
313 		spin_unlock_irqrestore(&priv->lock, flags);
314 		schedule_delayed_work(&priv->delayed_write_work, msecs_to_jiffies(2));
315 		return;
316 	}
317 	priv->flags.write_urb_in_use = 1;
318 
319 	count = oti6858_buf_data_avail(priv->buf);
320 	spin_unlock_irqrestore(&priv->lock, flags);
321 	if (count > port->bulk_out_size)
322 		count = port->bulk_out_size;
323 
324 	if (count != 0) {
325 		result = usb_control_msg(port->serial->dev,
326 				usb_rcvctrlpipe(port->serial->dev, 0),
327 				OTI6858_REQ_T_CHECK_TXBUFF,
328 				OTI6858_REQ_CHECK_TXBUFF,
329 				count, 0, &allow, 1, 100);
330 		if (result != 1 || allow != 0)
331 			count = 0;
332 	}
333 
334 	if (count == 0) {
335 		priv->flags.write_urb_in_use = 0;
336 
337 		dbg("%s(): submitting interrupt urb", __FUNCTION__);
338 		port->interrupt_in_urb->dev = port->serial->dev;
339 		result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
340 		if (result != 0) {
341 			dev_err(&port->dev, "%s(): usb_submit_urb() failed"
342 				" with error %d\n", __FUNCTION__, result);
343 		}
344 		return;
345 	}
346 
347 	spin_lock_irqsave(&priv->lock, flags);
348 	oti6858_buf_get(priv->buf, port->write_urb->transfer_buffer, count);
349 	spin_unlock_irqrestore(&priv->lock, flags);
350 
351 	port->write_urb->transfer_buffer_length = count;
352 	port->write_urb->dev = port->serial->dev;
353 	result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
354 	if (result != 0) {
355 		dev_err(&port->dev, "%s(): usb_submit_urb() failed"
356 			       " with error %d\n", __FUNCTION__, result);
357 		priv->flags.write_urb_in_use = 0;
358 	}
359 
360 	usb_serial_port_softint(port);
361 }
362 
363 static int oti6858_startup(struct usb_serial *serial)
364 {
365         struct usb_serial_port *port = serial->port[0];
366         struct oti6858_private *priv;
367 	int i;
368 
369 	for (i = 0; i < serial->num_ports; ++i) {
370 		priv = kzalloc(sizeof(struct oti6858_private), GFP_KERNEL);
371 		if (!priv)
372 			break;
373 		priv->buf = oti6858_buf_alloc(PL2303_BUF_SIZE);
374 		if (priv->buf == NULL) {
375 			kfree(priv);
376 			break;
377 		}
378 
379 		spin_lock_init(&priv->lock);
380 		init_waitqueue_head(&priv->intr_wait);
381 //		INIT_WORK(&priv->setup_work, setup_line, serial->port[i]);
382 //		INIT_WORK(&priv->write_work, send_data, serial->port[i]);
383 		priv->port = port;
384 		INIT_DELAYED_WORK(&priv->delayed_setup_work, setup_line);
385 		INIT_DELAYED_WORK(&priv->delayed_write_work, send_data);
386 
387 		usb_set_serial_port_data(serial->port[i], priv);
388 	}
389 	if (i == serial->num_ports)
390 		return 0;
391 
392 	for (--i; i >= 0; --i) {
393 		priv = usb_get_serial_port_data(serial->port[i]);
394 		oti6858_buf_free(priv->buf);
395 		kfree(priv);
396 		usb_set_serial_port_data(serial->port[i], NULL);
397 	}
398 	return -ENOMEM;
399 }
400 
401 static int oti6858_write(struct usb_serial_port *port,
402 			const unsigned char *buf, int count)
403 {
404 	struct oti6858_private *priv = usb_get_serial_port_data(port);
405 	unsigned long flags;
406 
407 	dbg("%s(port = %d, count = %d)", __FUNCTION__, port->number, count);
408 
409 	if (!count)
410 		return count;
411 
412 	spin_lock_irqsave(&priv->lock, flags);
413 	count = oti6858_buf_put(priv->buf, buf, count);
414 	spin_unlock_irqrestore(&priv->lock, flags);
415 
416 	return count;
417 }
418 
419 static int oti6858_write_room(struct usb_serial_port *port)
420 {
421 	struct oti6858_private *priv = usb_get_serial_port_data(port);
422 	int room = 0;
423 	unsigned long flags;
424 
425 	dbg("%s(port = %d)", __FUNCTION__, port->number);
426 
427 	spin_lock_irqsave(&priv->lock, flags);
428 	room = oti6858_buf_space_avail(priv->buf);
429 	spin_unlock_irqrestore(&priv->lock, flags);
430 
431 	return room;
432 }
433 
434 static int oti6858_chars_in_buffer(struct usb_serial_port *port)
435 {
436 	struct oti6858_private *priv = usb_get_serial_port_data(port);
437 	int chars = 0;
438 	unsigned long flags;
439 
440 	dbg("%s(port = %d)", __FUNCTION__, port->number);
441 
442 	spin_lock_irqsave(&priv->lock, flags);
443 	chars = oti6858_buf_data_avail(priv->buf);
444 	spin_unlock_irqrestore(&priv->lock, flags);
445 
446 	return chars;
447 }
448 
449 static void oti6858_set_termios(struct usb_serial_port *port,
450 				struct ktermios *old_termios)
451 {
452 	struct oti6858_private *priv = usb_get_serial_port_data(port);
453 	unsigned long flags;
454 	unsigned int cflag;
455 	u8 frame_fmt, control;
456 	u16 divisor;
457 	int br;
458 
459 	dbg("%s(port = %d)", __FUNCTION__, port->number);
460 
461 	if (!port->tty || !port->tty->termios) {
462 		dbg("%s(): no tty structures", __FUNCTION__);
463 		return;
464 	}
465 
466 	spin_lock_irqsave(&priv->lock, flags);
467 	if (!priv->flags.termios_initialized) {
468 		*(port->tty->termios) = tty_std_termios;
469 		port->tty->termios->c_cflag = B38400 | CS8 | CREAD | HUPCL | CLOCAL;
470 		priv->flags.termios_initialized = 1;
471 		port->tty->termios->c_ispeed = 38400;
472 		port->tty->termios->c_ospeed = 38400;
473 	}
474 	spin_unlock_irqrestore(&priv->lock, flags);
475 
476 	cflag = port->tty->termios->c_cflag;
477 
478 	spin_lock_irqsave(&priv->lock, flags);
479 	divisor = priv->pending_setup.divisor;
480 	frame_fmt = priv->pending_setup.frame_fmt;
481 	control = priv->pending_setup.control;
482 	spin_unlock_irqrestore(&priv->lock, flags);
483 
484 	frame_fmt &= ~FMT_DATA_BITS_MASK;
485 	switch (cflag & CSIZE) {
486 		case CS5:
487 			frame_fmt |= FMT_DATA_BITS_5;
488 			break;
489 		case CS6:
490 			frame_fmt |= FMT_DATA_BITS_6;
491 			break;
492 		case CS7:
493 			frame_fmt |= FMT_DATA_BITS_7;
494 			break;
495 		default:
496 		case CS8:
497 			frame_fmt |= FMT_DATA_BITS_8;
498 			break;
499 	}
500 
501 	/* manufacturer claims that this device can work with baud rates
502 	 * up to 3 Mbps; I've tested it only on 115200 bps, so I can't
503 	 * guarantee that any other baud rate will work (especially
504 	 * the higher ones)
505 	 */
506 	br = tty_get_baud_rate(port->tty);
507 	if (br == 0) {
508 		divisor = 0;
509 	} else {
510 		int real_br;
511 		br = min(br, OTI6858_MAX_BAUD_RATE);
512 
513 		divisor = (96000000 + 8 * br) / (16 * br);
514 		real_br = 96000000 / (16 * divisor);
515 		divisor = cpu_to_le16(divisor);
516 		tty_encode_baud_rate(port->tty, real_br, real_br);
517 	}
518 
519 	frame_fmt &= ~FMT_STOP_BITS_MASK;
520 	if ((cflag & CSTOPB) != 0) {
521 		frame_fmt |= FMT_STOP_BITS_2;
522 	} else {
523 		frame_fmt |= FMT_STOP_BITS_1;
524 	}
525 
526 	frame_fmt &= ~FMT_PARITY_MASK;
527 	if ((cflag & PARENB) != 0) {
528 		if ((cflag & PARODD) != 0) {
529 			frame_fmt |= FMT_PARITY_ODD;
530 		} else {
531 			frame_fmt |= FMT_PARITY_EVEN;
532 		}
533 	} else {
534 		frame_fmt |= FMT_PARITY_NONE;
535 	}
536 
537 	control &= ~CONTROL_MASK;
538 	if ((cflag & CRTSCTS) != 0)
539 		control |= (CONTROL_DTR_HIGH | CONTROL_RTS_HIGH);
540 
541 	/* change control lines if we are switching to or from B0 */
542 	/* FIXME:
543 	spin_lock_irqsave(&priv->lock, flags);
544 	control = priv->line_control;
545 	if ((cflag & CBAUD) == B0)
546 		priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
547 	else
548 		priv->line_control |= (CONTROL_DTR | CONTROL_RTS);
549 	if (control != priv->line_control) {
550 		control = priv->line_control;
551 		spin_unlock_irqrestore(&priv->lock, flags);
552 		set_control_lines(serial->dev, control);
553 	} else {
554 		spin_unlock_irqrestore(&priv->lock, flags);
555 	}
556 	*/
557 
558 	spin_lock_irqsave(&priv->lock, flags);
559 	if (divisor != priv->pending_setup.divisor
560 			|| control != priv->pending_setup.control
561 			|| frame_fmt != priv->pending_setup.frame_fmt) {
562 		priv->pending_setup.divisor = divisor;
563 		priv->pending_setup.control = control;
564 		priv->pending_setup.frame_fmt = frame_fmt;
565 	}
566 	spin_unlock_irqrestore(&priv->lock, flags);
567 }
568 
569 static int oti6858_open(struct usb_serial_port *port, struct file *filp)
570 {
571 	struct oti6858_private *priv = usb_get_serial_port_data(port);
572 	struct ktermios tmp_termios;
573 	struct usb_serial *serial = port->serial;
574 	struct oti6858_control_pkt *buf;
575 	unsigned long flags;
576 	int result;
577 
578 	dbg("%s(port = %d)", __FUNCTION__, port->number);
579 
580 	usb_clear_halt(serial->dev, port->write_urb->pipe);
581 	usb_clear_halt(serial->dev, port->read_urb->pipe);
582 
583 	if (port->open_count != 1)
584 		return 0;
585 
586 	if ((buf = kmalloc(OTI6858_CTRL_PKT_SIZE, GFP_KERNEL)) == NULL) {
587 		dev_err(&port->dev, "%s(): out of memory!\n", __FUNCTION__);
588 		return -ENOMEM;
589 	}
590 
591 	result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
592 				OTI6858_REQ_T_GET_STATUS,
593 				OTI6858_REQ_GET_STATUS,
594 				0, 0,
595 				buf, OTI6858_CTRL_PKT_SIZE,
596 				100);
597 	if (result != OTI6858_CTRL_PKT_SIZE) {
598 		/* assume default (after power-on reset) values */
599 		buf->divisor = cpu_to_le16(0x009c);	/* 38400 bps */
600 		buf->frame_fmt = 0x03;	/* 8N1 */
601 		buf->something = 0x43;
602 		buf->control = 0x4c;	/* DTR, RTS */
603 		buf->tx_status = 0x00;
604 		buf->pin_state = 0x5b;	/* RTS, CTS, DSR, DTR, RI, DCD */
605 		buf->rx_bytes_avail = 0x00;
606 	}
607 
608 	spin_lock_irqsave(&priv->lock, flags);
609 	memcpy(&priv->status, buf, OTI6858_CTRL_PKT_SIZE);
610 	priv->pending_setup.divisor = buf->divisor;
611 	priv->pending_setup.frame_fmt = buf->frame_fmt;
612 	priv->pending_setup.control = buf->control;
613 	spin_unlock_irqrestore(&priv->lock, flags);
614 	kfree(buf);
615 
616 	dbg("%s(): submitting interrupt urb", __FUNCTION__);
617 	port->interrupt_in_urb->dev = serial->dev;
618 	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
619 	if (result != 0) {
620 		dev_err(&port->dev, "%s(): usb_submit_urb() failed"
621 			       " with error %d\n", __FUNCTION__, result);
622 		oti6858_close(port, NULL);
623 		return -EPROTO;
624 	}
625 
626 	/* setup termios */
627 	if (port->tty)
628 		oti6858_set_termios(port, &tmp_termios);
629 
630 	return 0;
631 }
632 
633 static void oti6858_close(struct usb_serial_port *port, struct file *filp)
634 {
635 	struct oti6858_private *priv = usb_get_serial_port_data(port);
636 	unsigned long flags;
637 	long timeout;
638 	wait_queue_t wait;
639 
640 	dbg("%s(port = %d)", __FUNCTION__, port->number);
641 
642 	/* wait for data to drain from the buffer */
643 	spin_lock_irqsave(&priv->lock, flags);
644 	timeout = 30 * HZ;	/* PL2303_CLOSING_WAIT */
645 	init_waitqueue_entry(&wait, current);
646 	add_wait_queue(&port->tty->write_wait, &wait);
647 	dbg("%s(): entering wait loop", __FUNCTION__);
648 	for (;;) {
649 		set_current_state(TASK_INTERRUPTIBLE);
650 		if (oti6858_buf_data_avail(priv->buf) == 0
651 		|| timeout == 0 || signal_pending(current)
652 		|| port->serial->disconnected)
653 			break;
654 		spin_unlock_irqrestore(&priv->lock, flags);
655 		timeout = schedule_timeout(timeout);
656 		spin_lock_irqsave(&priv->lock, flags);
657 	}
658 	set_current_state(TASK_RUNNING);
659 	remove_wait_queue(&port->tty->write_wait, &wait);
660 	dbg("%s(): after wait loop", __FUNCTION__);
661 
662 	/* clear out any remaining data in the buffer */
663 	oti6858_buf_clear(priv->buf);
664 	spin_unlock_irqrestore(&priv->lock, flags);
665 
666 	/* wait for characters to drain from the device */
667 	/* (this is long enough for the entire 256 byte */
668 	/* pl2303 hardware buffer to drain with no flow */
669 	/* control for data rates of 1200 bps or more, */
670 	/* for lower rates we should really know how much */
671 	/* data is in the buffer to compute a delay */
672 	/* that is not unnecessarily long) */
673 	/* FIXME
674 	bps = tty_get_baud_rate(port->tty);
675 	if (bps > 1200)
676 		timeout = max((HZ*2560)/bps,HZ/10);
677 	else
678 	*/
679 		timeout = 2*HZ;
680 	schedule_timeout_interruptible(timeout);
681 	dbg("%s(): after schedule_timeout_interruptible()", __FUNCTION__);
682 
683 	/* cancel scheduled setup */
684 	cancel_delayed_work(&priv->delayed_setup_work);
685 	cancel_delayed_work(&priv->delayed_write_work);
686 	flush_scheduled_work();
687 
688 	/* shutdown our urbs */
689 	dbg("%s(): shutting down urbs", __FUNCTION__);
690 	usb_kill_urb(port->write_urb);
691 	usb_kill_urb(port->read_urb);
692 	usb_kill_urb(port->interrupt_in_urb);
693 
694 	/*
695 	if (port->tty && (port->tty->termios->c_cflag) & HUPCL) {
696 		// drop DTR and RTS
697 		spin_lock_irqsave(&priv->lock, flags);
698 		priv->pending_setup.control &= ~CONTROL_MASK;
699 		spin_unlock_irqrestore(&priv->lock, flags);
700 	}
701 	*/
702 }
703 
704 static int oti6858_tiocmset(struct usb_serial_port *port, struct file *file,
705 				unsigned int set, unsigned int clear)
706 {
707 	struct oti6858_private *priv = usb_get_serial_port_data(port);
708 	unsigned long flags;
709 	u8 control;
710 
711 	dbg("%s(port = %d, set = 0x%08x, clear = 0x%08x)",
712 				__FUNCTION__, port->number, set, clear);
713 
714 	if (!usb_get_intfdata(port->serial->interface))
715 		return -ENODEV;
716 
717 	/* FIXME: check if this is correct (active high/low) */
718 	spin_lock_irqsave(&priv->lock, flags);
719 	control = priv->pending_setup.control;
720 	if ((set & TIOCM_RTS) != 0)
721 		control |= CONTROL_RTS_HIGH;
722 	if ((set & TIOCM_DTR) != 0)
723 		control |= CONTROL_DTR_HIGH;
724 	if ((clear & TIOCM_RTS) != 0)
725 		control &= ~CONTROL_RTS_HIGH;
726 	if ((clear & TIOCM_DTR) != 0)
727 		control &= ~CONTROL_DTR_HIGH;
728 
729 	if (control != priv->pending_setup.control) {
730 		priv->pending_setup.control = control;
731 	}
732 	spin_unlock_irqrestore(&priv->lock, flags);
733 
734 	return 0;
735 }
736 
737 static int oti6858_tiocmget(struct usb_serial_port *port, struct file *file)
738 {
739 	struct oti6858_private *priv = usb_get_serial_port_data(port);
740 	unsigned long flags;
741 	unsigned pin_state;
742 	unsigned result = 0;
743 
744 	dbg("%s(port = %d)", __FUNCTION__, port->number);
745 
746 	if (!usb_get_intfdata(port->serial->interface))
747 		return -ENODEV;
748 
749 	spin_lock_irqsave(&priv->lock, flags);
750 	pin_state = priv->status.pin_state & PIN_MASK;
751 	spin_unlock_irqrestore(&priv->lock, flags);
752 
753 	/* FIXME: check if this is correct (active high/low) */
754 	if ((pin_state & PIN_RTS) != 0)
755 		result |= TIOCM_RTS;
756 	if ((pin_state & PIN_CTS) != 0)
757 		result |= TIOCM_CTS;
758 	if ((pin_state & PIN_DSR) != 0)
759 		result |= TIOCM_DSR;
760 	if ((pin_state & PIN_DTR) != 0)
761 		result |= TIOCM_DTR;
762 	if ((pin_state & PIN_RI) != 0)
763 		result |= TIOCM_RI;
764 	if ((pin_state & PIN_DCD) != 0)
765 		result |= TIOCM_CD;
766 
767 	dbg("%s() = 0x%08x", __FUNCTION__, result);
768 
769 	return result;
770 }
771 
772 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
773 {
774 	struct oti6858_private *priv = usb_get_serial_port_data(port);
775 	unsigned long flags;
776 	unsigned int prev, status;
777 	unsigned int changed;
778 
779 	spin_lock_irqsave(&priv->lock, flags);
780 	prev = priv->status.pin_state;
781 	spin_unlock_irqrestore(&priv->lock, flags);
782 
783 	while (1) {
784 		wait_event_interruptible(priv->intr_wait, priv->status.pin_state != prev);
785 		if (signal_pending(current))
786 			return -ERESTARTSYS;
787 
788 		spin_lock_irqsave(&priv->lock, flags);
789 		status = priv->status.pin_state & PIN_MASK;
790 		spin_unlock_irqrestore(&priv->lock, flags);
791 
792 		changed = prev ^ status;
793 		/* FIXME: check if this is correct (active high/low) */
794 		if (	((arg & TIOCM_RNG) && (changed & PIN_RI)) ||
795 			((arg & TIOCM_DSR) && (changed & PIN_DSR)) ||
796 			((arg & TIOCM_CD)  && (changed & PIN_DCD)) ||
797 			((arg & TIOCM_CTS) && (changed & PIN_CTS))) {
798 				return 0;
799 		}
800 		prev = status;
801 	}
802 
803 	/* NOTREACHED */
804 	return 0;
805 }
806 
807 static int oti6858_ioctl(struct usb_serial_port *port, struct file *file,
808 			unsigned int cmd, unsigned long arg)
809 {
810 	void __user *user_arg = (void __user *) arg;
811 	unsigned int x;
812 
813 	dbg("%s(port = %d, cmd = 0x%04x, arg = 0x%08lx)",
814 				__FUNCTION__, port->number, cmd, arg);
815 
816 	switch (cmd) {
817 		case TCFLSH:
818 			/* FIXME */
819 			return 0;
820 
821 		case TIOCMBIS:
822 			if (copy_from_user(&x, user_arg, sizeof(x)))
823 				return -EFAULT;
824 			return oti6858_tiocmset(port, NULL, x, 0);
825 
826 		case TIOCMBIC:
827 			if (copy_from_user(&x, user_arg, sizeof(x)))
828 				return -EFAULT;
829 			return oti6858_tiocmset(port, NULL, 0, x);
830 
831 		case TIOCMIWAIT:
832 			dbg("%s(): TIOCMIWAIT", __FUNCTION__);
833 			return wait_modem_info(port, arg);
834 
835 		default:
836 			dbg("%s(): 0x%04x not supported", __FUNCTION__, cmd);
837 			break;
838 	}
839 
840 	return -ENOIOCTLCMD;
841 }
842 
843 static void oti6858_break_ctl(struct usb_serial_port *port, int break_state)
844 {
845 	int state;
846 
847 	dbg("%s(port = %d)", __FUNCTION__, port->number);
848 
849 	state = (break_state == 0) ? 0 : 1;
850 	dbg("%s(): turning break %s", __FUNCTION__, state ? "on" : "off");
851 
852 	/* FIXME */
853 /*
854 	result = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
855 				  BREAK_REQUEST, BREAK_REQUEST_TYPE, state,
856 				  0, NULL, 0, 100);
857 	if (result != 0)
858 		dbg("%s(): error sending break", __FUNCTION__);
859  */
860 }
861 
862 static void oti6858_shutdown(struct usb_serial *serial)
863 {
864 	struct oti6858_private *priv;
865 	int i;
866 
867 	dbg("%s()", __FUNCTION__);
868 
869 	for (i = 0; i < serial->num_ports; ++i) {
870 		priv = usb_get_serial_port_data(serial->port[i]);
871 		if (priv) {
872 			oti6858_buf_free(priv->buf);
873 			kfree(priv);
874 			usb_set_serial_port_data(serial->port[i], NULL);
875 		}
876 	}
877 }
878 
879 static void oti6858_read_int_callback(struct urb *urb)
880 {
881 	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
882 	struct oti6858_private *priv = usb_get_serial_port_data(port);
883 	int transient = 0, can_recv = 0, resubmit = 1;
884 	int status = urb->status;
885 
886 	dbg("%s(port = %d, status = %d)",
887 				__FUNCTION__, port->number, status);
888 
889 	switch (status) {
890 	case 0:
891 		/* success */
892 		break;
893 	case -ECONNRESET:
894 	case -ENOENT:
895 	case -ESHUTDOWN:
896 		/* this urb is terminated, clean up */
897 		dbg("%s(): urb shutting down with status: %d",
898 					__FUNCTION__, status);
899 		return;
900 	default:
901 		dbg("%s(): nonzero urb status received: %d",
902 					__FUNCTION__, status);
903 		break;
904 	}
905 
906 	if (status == 0 && urb->actual_length == OTI6858_CTRL_PKT_SIZE) {
907 		struct oti6858_control_pkt *xs = urb->transfer_buffer;
908 		unsigned long flags;
909 
910 		spin_lock_irqsave(&priv->lock, flags);
911 
912 		if (!priv->transient) {
913 			if (!OTI6858_CTRL_EQUALS_PENDING(xs, priv)) {
914 				if (xs->rx_bytes_avail == 0) {
915 					priv->transient = 4;
916 					priv->setup_done = 0;
917 					resubmit = 0;
918 					dbg("%s(): scheduling setup_line()",
919 					    __FUNCTION__);
920 					schedule_delayed_work(&priv->delayed_setup_work, 0);
921 				}
922 			}
923 		} else {
924 			if (OTI6858_CTRL_EQUALS_PENDING(xs, priv)) {
925 				priv->transient = 0;
926 			} else if (!priv->setup_done) {
927 				resubmit = 0;
928 			} else if (--priv->transient == 0) {
929 				if (xs->rx_bytes_avail == 0) {
930 					priv->transient = 4;
931 					priv->setup_done = 0;
932 					resubmit = 0;
933 					dbg("%s(): scheduling setup_line()",
934 					    __FUNCTION__);
935 					schedule_delayed_work(&priv->delayed_setup_work, 0);
936 				}
937 			}
938 		}
939 
940 		if (!priv->transient) {
941 			if (xs->pin_state != priv->status.pin_state)
942 				wake_up_interruptible(&priv->intr_wait);
943 			memcpy(&priv->status, xs, OTI6858_CTRL_PKT_SIZE);
944 		}
945 
946 		if (!priv->transient && xs->rx_bytes_avail != 0) {
947 			can_recv = xs->rx_bytes_avail;
948 			priv->flags.read_urb_in_use = 1;
949 		}
950 
951 		transient = priv->transient;
952 		spin_unlock_irqrestore(&priv->lock, flags);
953 	}
954 
955 	if (can_recv) {
956 		int result;
957 
958 		port->read_urb->dev = port->serial->dev;
959 		result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
960 		if (result != 0) {
961 			priv->flags.read_urb_in_use = 0;
962 			dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
963 					" error %d\n", __FUNCTION__, result);
964 		} else {
965 			resubmit = 0;
966 		}
967 	} else if (!transient) {
968 		unsigned long flags;
969 
970 		spin_lock_irqsave(&priv->lock, flags);
971 		if (priv->flags.write_urb_in_use == 0
972 				&& oti6858_buf_data_avail(priv->buf) != 0) {
973 			schedule_delayed_work(&priv->delayed_write_work,0);
974 			resubmit = 0;
975 		}
976 		spin_unlock_irqrestore(&priv->lock, flags);
977 	}
978 
979 	if (resubmit) {
980 		int result;
981 
982 //		dbg("%s(): submitting interrupt urb", __FUNCTION__);
983 		urb->dev = port->serial->dev;
984 		result = usb_submit_urb(urb, GFP_ATOMIC);
985 		if (result != 0) {
986 			dev_err(&urb->dev->dev,
987 					"%s(): usb_submit_urb() failed with"
988 					" error %d\n", __FUNCTION__, result);
989 		}
990 	}
991 }
992 
993 static void oti6858_read_bulk_callback(struct urb *urb)
994 {
995 	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
996 	struct oti6858_private *priv = usb_get_serial_port_data(port);
997 	struct tty_struct *tty;
998 	unsigned char *data = urb->transfer_buffer;
999 	unsigned long flags;
1000 	int status = urb->status;
1001 	int result;
1002 
1003 	dbg("%s(port = %d, status = %d)",
1004 				__FUNCTION__, port->number, status);
1005 
1006 	spin_lock_irqsave(&priv->lock, flags);
1007 	priv->flags.read_urb_in_use = 0;
1008 	spin_unlock_irqrestore(&priv->lock, flags);
1009 
1010 	if (status != 0) {
1011 		if (!port->open_count) {
1012 			dbg("%s(): port is closed, exiting", __FUNCTION__);
1013 			return;
1014 		}
1015 		/*
1016 		if (status == -EPROTO) {
1017 			// PL2303 mysteriously fails with -EPROTO reschedule the read
1018 			dbg("%s - caught -EPROTO, resubmitting the urb", __FUNCTION__);
1019 			result = usb_submit_urb(urb, GFP_ATOMIC);
1020 			if (result)
1021 				dev_err(&urb->dev->dev, "%s - failed resubmitting read urb, error %d\n", __FUNCTION__, result);
1022 			return;
1023 		}
1024 		*/
1025 		dbg("%s(): unable to handle the error, exiting", __FUNCTION__);
1026 		return;
1027 	}
1028 
1029 	tty = port->tty;
1030 	if (tty != NULL && urb->actual_length > 0) {
1031 		tty_insert_flip_string(tty, data, urb->actual_length);
1032 		tty_flip_buffer_push(tty);
1033 	}
1034 
1035 	// schedule the interrupt urb if we are still open */
1036 	if (port->open_count != 0) {
1037 		port->interrupt_in_urb->dev = port->serial->dev;
1038 		result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
1039 		if (result != 0) {
1040 			dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
1041 					" error %d\n", __FUNCTION__, result);
1042 		}
1043 	}
1044 }
1045 
1046 static void oti6858_write_bulk_callback(struct urb *urb)
1047 {
1048 	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
1049 	struct oti6858_private *priv = usb_get_serial_port_data(port);
1050 	int status = urb->status;
1051 	int result;
1052 
1053 	dbg("%s(port = %d, status = %d)",
1054 				__FUNCTION__, port->number, status);
1055 
1056 	switch (status) {
1057 	case 0:
1058 		/* success */
1059 		break;
1060 	case -ECONNRESET:
1061 	case -ENOENT:
1062 	case -ESHUTDOWN:
1063 		/* this urb is terminated, clean up */
1064 		dbg("%s(): urb shutting down with status: %d",
1065 					__FUNCTION__, status);
1066 		priv->flags.write_urb_in_use = 0;
1067 		return;
1068 	default:
1069 		/* error in the urb, so we have to resubmit it */
1070 		dbg("%s(): nonzero write bulk status received: %d",
1071 					__FUNCTION__, status);
1072 		dbg("%s(): overflow in write", __FUNCTION__);
1073 
1074 		port->write_urb->transfer_buffer_length = 1;
1075 		port->write_urb->dev = port->serial->dev;
1076 		result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
1077 		if (result) {
1078 			dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
1079 					" error %d\n", __FUNCTION__, result);
1080 		} else {
1081 			return;
1082 		}
1083 	}
1084 
1085 	priv->flags.write_urb_in_use = 0;
1086 
1087 	// schedule the interrupt urb if we are still open */
1088 	port->interrupt_in_urb->dev = port->serial->dev;
1089 	dbg("%s(): submitting interrupt urb", __FUNCTION__);
1090 	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
1091 	if (result != 0) {
1092 		dev_err(&port->dev, "%s(): failed submitting int urb,"
1093 					" error %d\n", __FUNCTION__, result);
1094 	}
1095 }
1096 
1097 
1098 /*
1099  * oti6858_buf_alloc
1100  *
1101  * Allocate a circular buffer and all associated memory.
1102  */
1103 static struct oti6858_buf *oti6858_buf_alloc(unsigned int size)
1104 {
1105 	struct oti6858_buf *pb;
1106 
1107 	if (size == 0)
1108 		return NULL;
1109 
1110 	pb = kmalloc(sizeof(struct oti6858_buf), GFP_KERNEL);
1111 	if (pb == NULL)
1112 		return NULL;
1113 
1114 	pb->buf_buf = kmalloc(size, GFP_KERNEL);
1115 	if (pb->buf_buf == NULL) {
1116 		kfree(pb);
1117 		return NULL;
1118 	}
1119 
1120 	pb->buf_size = size;
1121 	pb->buf_get = pb->buf_put = pb->buf_buf;
1122 
1123 	return pb;
1124 }
1125 
1126 /*
1127  * oti6858_buf_free
1128  *
1129  * Free the buffer and all associated memory.
1130  */
1131 static void oti6858_buf_free(struct oti6858_buf *pb)
1132 {
1133 	if (pb) {
1134 		kfree(pb->buf_buf);
1135 		kfree(pb);
1136 	}
1137 }
1138 
1139 /*
1140  * oti6858_buf_clear
1141  *
1142  * Clear out all data in the circular buffer.
1143  */
1144 static void oti6858_buf_clear(struct oti6858_buf *pb)
1145 {
1146 	if (pb != NULL) {
1147 		/* equivalent to a get of all data available */
1148 		pb->buf_get = pb->buf_put;
1149 	}
1150 }
1151 
1152 /*
1153  * oti6858_buf_data_avail
1154  *
1155  * Return the number of bytes of data available in the circular
1156  * buffer.
1157  */
1158 static unsigned int oti6858_buf_data_avail(struct oti6858_buf *pb)
1159 {
1160 	if (pb == NULL)
1161 		return 0;
1162 	return ((pb->buf_size + pb->buf_put - pb->buf_get) % pb->buf_size);
1163 }
1164 
1165 /*
1166  * oti6858_buf_space_avail
1167  *
1168  * Return the number of bytes of space available in the circular
1169  * buffer.
1170  */
1171 static unsigned int oti6858_buf_space_avail(struct oti6858_buf *pb)
1172 {
1173 	if (pb == NULL)
1174 		return 0;
1175 	return ((pb->buf_size + pb->buf_get - pb->buf_put - 1) % pb->buf_size);
1176 }
1177 
1178 /*
1179  * oti6858_buf_put
1180  *
1181  * Copy data data from a user buffer and put it into the circular buffer.
1182  * Restrict to the amount of space available.
1183  *
1184  * Return the number of bytes copied.
1185  */
1186 static unsigned int oti6858_buf_put(struct oti6858_buf *pb, const char *buf,
1187 					unsigned int count)
1188 {
1189 	unsigned int len;
1190 
1191 	if (pb == NULL)
1192 		return 0;
1193 
1194 	len  = oti6858_buf_space_avail(pb);
1195 	if (count > len)
1196 		count = len;
1197 
1198 	if (count == 0)
1199 		return 0;
1200 
1201 	len = pb->buf_buf + pb->buf_size - pb->buf_put;
1202 	if (count > len) {
1203 		memcpy(pb->buf_put, buf, len);
1204 		memcpy(pb->buf_buf, buf+len, count - len);
1205 		pb->buf_put = pb->buf_buf + count - len;
1206 	} else {
1207 		memcpy(pb->buf_put, buf, count);
1208 		if (count < len)
1209 			pb->buf_put += count;
1210 		else /* count == len */
1211 			pb->buf_put = pb->buf_buf;
1212 	}
1213 
1214 	return count;
1215 }
1216 
1217 /*
1218  * oti6858_buf_get
1219  *
1220  * Get data from the circular buffer and copy to the given buffer.
1221  * Restrict to the amount of data available.
1222  *
1223  * Return the number of bytes copied.
1224  */
1225 static unsigned int oti6858_buf_get(struct oti6858_buf *pb, char *buf,
1226 					unsigned int count)
1227 {
1228 	unsigned int len;
1229 
1230 	if (pb == NULL)
1231 		return 0;
1232 
1233 	len = oti6858_buf_data_avail(pb);
1234 	if (count > len)
1235 		count = len;
1236 
1237 	if (count == 0)
1238 		return 0;
1239 
1240 	len = pb->buf_buf + pb->buf_size - pb->buf_get;
1241 	if (count > len) {
1242 		memcpy(buf, pb->buf_get, len);
1243 		memcpy(buf+len, pb->buf_buf, count - len);
1244 		pb->buf_get = pb->buf_buf + count - len;
1245 	} else {
1246 		memcpy(buf, pb->buf_get, count);
1247 		if (count < len)
1248 			pb->buf_get += count;
1249 		else /* count == len */
1250 			pb->buf_get = pb->buf_buf;
1251 	}
1252 
1253 	return count;
1254 }
1255 
1256 /* module description and (de)initialization */
1257 
1258 static int __init oti6858_init(void)
1259 {
1260 	int retval;
1261 
1262 	if ((retval = usb_serial_register(&oti6858_device)) == 0) {
1263 		if ((retval = usb_register(&oti6858_driver)) != 0)
1264 			usb_serial_deregister(&oti6858_device);
1265 		else
1266 			return 0;
1267 	}
1268 
1269 	return retval;
1270 }
1271 
1272 static void __exit oti6858_exit(void)
1273 {
1274 	usb_deregister(&oti6858_driver);
1275 	usb_serial_deregister(&oti6858_device);
1276 }
1277 
1278 module_init(oti6858_init);
1279 module_exit(oti6858_exit);
1280 
1281 MODULE_DESCRIPTION(OTI6858_DESCRIPTION);
1282 MODULE_AUTHOR(OTI6858_AUTHOR);
1283 MODULE_VERSION(OTI6858_VERSION);
1284 MODULE_LICENSE("GPL");
1285 
1286 module_param(debug, bool, S_IRUGO | S_IWUSR);
1287 MODULE_PARM_DESC(debug, "enable debug output");
1288 
1289