2
* Copyright (C) 2009 by Bart Hartgers (bart.hartgers+ark3116@gmail.com)
5
* Simon Schulz (ark3116_driver <at> auctionant.de)
8
* - implements a driver for the arkmicro ark3116 chipset (vendor=0x6547,
9
* productid=0x0232) (used in a datacable called KQ-U8A)
11
* Supports full modem status lines, break, hardware flow control. Does not
12
* support software flow control, since I do not know how to enable it in hw.
14
* This driver is a essentially new implementation. I initially dug
15
* into the old ark3116.c driver and suddenly realized the ark3116 is
16
* a 16450 with a USB interface glued to it. See comments at the
17
* bottom of this file.
19
* This program is free software; you can redistribute it and/or modify it
20
* under the terms of the GNU General Public License as published by the
21
* Free Software Foundation; either version 2 of the License, or (at your
22
* option) any later version.
25
#include <linux/kernel.h>
26
#include <linux/init.h>
27
#include <linux/ioctl.h>
28
#include <linux/tty.h>
29
#include <linux/slab.h>
30
#include <linux/tty_flip.h>
31
#include <linux/module.h>
32
#include <linux/usb.h>
33
#include <linux/usb/serial.h>
34
#include <linux/serial.h>
35
#include <linux/serial_reg.h>
36
#include <linux/uaccess.h>
37
#include <linux/mutex.h>
38
#include <linux/spinlock.h>
45
#define DRIVER_VERSION "v0.6"
46
#define DRIVER_AUTHOR "Bart Hartgers <bart.hartgers+ark3116@gmail.com>"
47
#define DRIVER_DESC "USB ARK3116 serial/IrDA driver"
48
#define DRIVER_DEV_DESC "ARK3116 RS232/IrDA"
49
#define DRIVER_NAME "ark3116"
51
/* usb timeout of 1 second */
52
#define ARK_TIMEOUT (1*HZ)
54
static const struct usb_device_id id_table[] = {
55
{ USB_DEVICE(0x6547, 0x0232) },
56
{ USB_DEVICE(0x18ec, 0x3118) }, /* USB to IrDA adapter */
59
MODULE_DEVICE_TABLE(usb, id_table);
61
static int is_irda(struct usb_serial *serial)
63
struct usb_device *dev = serial->dev;
64
if (le16_to_cpu(dev->descriptor.idVendor) == 0x18ec &&
65
le16_to_cpu(dev->descriptor.idProduct) == 0x3118)
70
struct ark3116_private {
71
wait_queue_head_t delta_msr_wait;
72
struct async_icount icount;
73
int irda; /* 1 for irda device */
75
/* protects hw register updates */
78
int quot; /* baudrate divisor */
79
__u32 lcr; /* line control register value */
80
__u32 hcr; /* handshake control register (0x8)
82
__u32 mcr; /* modem contol register value */
84
/* protects the status values below */
85
spinlock_t status_lock;
86
__u32 msr; /* modem status register value */
87
__u32 lsr; /* line status register value */
90
static int ark3116_write_reg(struct usb_serial *serial,
91
unsigned reg, __u8 val)
94
/* 0xfe 0x40 are magic values taken from original driver */
95
result = usb_control_msg(serial->dev,
96
usb_sndctrlpipe(serial->dev, 0),
98
NULL, 0, ARK_TIMEOUT);
102
static int ark3116_read_reg(struct usb_serial *serial,
103
unsigned reg, unsigned char *buf)
106
/* 0xfe 0xc0 are magic values taken from original driver */
107
result = usb_control_msg(serial->dev,
108
usb_rcvctrlpipe(serial->dev, 0),
110
buf, 1, ARK_TIMEOUT);
117
static inline int calc_divisor(int bps)
119
/* Original ark3116 made some exceptions in rounding here
120
* because windows did the same. Assume that is not really
122
* Crystal is 12MHz, probably because of USB, but we divide by 4?
124
return (12000000 + 2*bps) / (4*bps);
127
static int ark3116_attach(struct usb_serial *serial)
129
struct usb_serial_port *port = serial->port[0];
130
struct ark3116_private *priv;
132
/* make sure we have our end-points */
133
if ((serial->num_bulk_in == 0) ||
134
(serial->num_bulk_out == 0) ||
135
(serial->num_interrupt_in == 0)) {
136
dev_err(&serial->dev->dev,
137
"%s - missing endpoint - "
138
"bulk in: %d, bulk out: %d, int in %d\n",
141
serial->num_bulk_out,
142
serial->num_interrupt_in);
146
priv = kzalloc(sizeof(struct ark3116_private),
151
init_waitqueue_head(&priv->delta_msr_wait);
152
mutex_init(&priv->hw_lock);
153
spin_lock_init(&priv->status_lock);
155
priv->irda = is_irda(serial);
157
usb_set_serial_port_data(port, priv);
159
/* setup the hardware */
160
ark3116_write_reg(serial, UART_IER, 0);
162
ark3116_write_reg(serial, UART_FCR, 0);
163
/* handshake control */
165
ark3116_write_reg(serial, 0x8 , 0);
168
ark3116_write_reg(serial, UART_MCR, 0);
171
ark3116_write_reg(serial, 0xb , 0);
173
ark3116_write_reg(serial, 0xb , 1);
174
ark3116_write_reg(serial, 0xc , 0);
175
ark3116_write_reg(serial, 0xd , 0x41);
176
ark3116_write_reg(serial, 0xa , 1);
180
ark3116_write_reg(serial, UART_LCR, UART_LCR_DLAB);
182
/* setup for 9600 8N1 */
183
priv->quot = calc_divisor(9600);
184
ark3116_write_reg(serial, UART_DLL, priv->quot & 0xff);
185
ark3116_write_reg(serial, UART_DLM, (priv->quot>>8) & 0xff);
187
priv->lcr = UART_LCR_WLEN8;
188
ark3116_write_reg(serial, UART_LCR, UART_LCR_WLEN8);
190
ark3116_write_reg(serial, 0xe, 0);
193
ark3116_write_reg(serial, 0x9, 0);
195
dev_info(&serial->dev->dev,
196
"%s using %s mode\n",
198
priv->irda ? "IrDA" : "RS232");
202
static void ark3116_release(struct usb_serial *serial)
204
struct usb_serial_port *port = serial->port[0];
205
struct ark3116_private *priv = usb_get_serial_port_data(port);
207
/* device is closed, so URBs and DMA should be down */
209
usb_set_serial_port_data(port, NULL);
211
mutex_destroy(&priv->hw_lock);
216
static void ark3116_init_termios(struct tty_struct *tty)
218
struct ktermios *termios = tty->termios;
219
*termios = tty_std_termios;
220
termios->c_cflag = B9600 | CS8
221
| CREAD | HUPCL | CLOCAL;
222
termios->c_ispeed = 9600;
223
termios->c_ospeed = 9600;
226
static void ark3116_set_termios(struct tty_struct *tty,
227
struct usb_serial_port *port,
228
struct ktermios *old_termios)
230
struct usb_serial *serial = port->serial;
231
struct ark3116_private *priv = usb_get_serial_port_data(port);
232
struct ktermios *termios = tty->termios;
233
unsigned int cflag = termios->c_cflag;
234
int bps = tty_get_baud_rate(tty);
238
/* set data bit count */
239
switch (cflag & CSIZE) {
241
lcr = UART_LCR_WLEN5;
244
lcr = UART_LCR_WLEN6;
247
lcr = UART_LCR_WLEN7;
251
lcr = UART_LCR_WLEN8;
255
lcr |= UART_LCR_STOP;
257
lcr |= UART_LCR_PARITY;
258
if (!(cflag & PARODD))
259
lcr |= UART_LCR_EPAR;
262
lcr |= UART_LCR_SPAR;
264
/* handshake control */
265
hcr = (cflag & CRTSCTS) ? 0x03 : 0x00;
268
dbg("%s - setting bps to %d", __func__, bps);
272
quot = calc_divisor(9600);
275
if ((bps < 75) || (bps > 3000000))
277
quot = calc_divisor(bps);
281
quot = calc_divisor(bps);
285
quot = calc_divisor(bps);
289
/* Update state: synchronize */
290
mutex_lock(&priv->hw_lock);
292
/* keep old LCR_SBC bit */
293
lcr |= (priv->lcr & UART_LCR_SBC);
295
dbg("%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d",
296
__func__, hcr, lcr, quot);
298
/* handshake control */
299
if (priv->hcr != hcr) {
301
ark3116_write_reg(serial, 0x8, hcr);
305
if (priv->quot != quot) {
307
priv->lcr = lcr; /* need to write lcr anyway */
309
/* disable DMA since transmit/receive is
310
* shadowed by UART_DLL
312
ark3116_write_reg(serial, UART_FCR, 0);
314
ark3116_write_reg(serial, UART_LCR,
316
ark3116_write_reg(serial, UART_DLL, quot & 0xff);
317
ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff);
320
ark3116_write_reg(serial, UART_LCR, lcr);
321
/* magic baudrate thingy: not sure what it does,
322
* but windows does this as well.
324
ark3116_write_reg(serial, 0xe, eval);
327
ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT);
328
} else if (priv->lcr != lcr) {
330
ark3116_write_reg(serial, UART_LCR, lcr);
333
mutex_unlock(&priv->hw_lock);
335
/* check for software flow control */
336
if (I_IXOFF(tty) || I_IXON(tty)) {
337
dev_warn(&serial->dev->dev,
338
"%s: don't know how to do software flow control\n",
342
/* Don't rewrite B0 */
343
if (tty_termios_baud_rate(termios))
344
tty_termios_encode_baud_rate(termios, bps, bps);
347
static void ark3116_close(struct usb_serial_port *port)
349
struct usb_serial *serial = port->serial;
353
ark3116_write_reg(serial, UART_FCR, 0);
355
/* deactivate interrupts */
356
ark3116_write_reg(serial, UART_IER, 0);
358
usb_serial_generic_close(port);
359
if (serial->num_interrupt_in)
360
usb_kill_urb(port->interrupt_in_urb);
365
static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port)
367
struct ark3116_private *priv = usb_get_serial_port_data(port);
368
struct usb_serial *serial = port->serial;
372
buf = kmalloc(1, GFP_KERNEL);
376
result = usb_serial_generic_open(tty, port);
378
dbg("%s - usb_serial_generic_open failed: %d",
385
ark3116_set_termios(tty, port, NULL);
387
/* remove any data still left: also clears error state */
388
ark3116_read_reg(serial, UART_RX, buf);
390
/* read modem status */
391
priv->msr = ark3116_read_reg(serial, UART_MSR, buf);
392
/* read line status */
393
priv->lsr = ark3116_read_reg(serial, UART_LSR, buf);
395
result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
397
dev_err(&port->dev, "submit irq_in urb failed %d\n",
403
/* activate interrupts */
404
ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI);
407
ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT);
414
static int ark3116_ioctl(struct tty_struct *tty, struct file *file,
415
unsigned int cmd, unsigned long arg)
417
struct usb_serial_port *port = tty->driver_data;
418
struct ark3116_private *priv = usb_get_serial_port_data(port);
419
struct serial_struct serstruct;
420
void __user *user_arg = (void __user *)arg;
424
/* XXX: Some of these values are probably wrong. */
425
memset(&serstruct, 0, sizeof(serstruct));
426
serstruct.type = PORT_16654;
427
serstruct.line = port->serial->minor;
428
serstruct.port = port->number;
429
serstruct.custom_divisor = 0;
430
serstruct.baud_base = 460800;
432
if (copy_to_user(user_arg, &serstruct, sizeof(serstruct)))
437
if (copy_from_user(&serstruct, user_arg, sizeof(serstruct)))
442
struct async_icount prev = priv->icount;
443
interruptible_sleep_on(&priv->delta_msr_wait);
444
/* see if a signal did it */
445
if (signal_pending(current))
447
if ((prev.rng == priv->icount.rng) &&
448
(prev.dsr == priv->icount.dsr) &&
449
(prev.dcd == priv->icount.dcd) &&
450
(prev.cts == priv->icount.cts))
452
if ((arg & TIOCM_RNG &&
453
(prev.rng != priv->icount.rng)) ||
455
(prev.dsr != priv->icount.dsr)) ||
457
(prev.dcd != priv->icount.dcd)) ||
459
(prev.cts != priv->icount.cts)))
464
struct serial_icounter_struct icount;
465
struct async_icount cnow = priv->icount;
466
memset(&icount, 0, sizeof(icount));
467
icount.cts = cnow.cts;
468
icount.dsr = cnow.dsr;
469
icount.rng = cnow.rng;
470
icount.dcd = cnow.dcd;
473
icount.frame = cnow.frame;
474
icount.overrun = cnow.overrun;
475
icount.parity = cnow.parity;
476
icount.brk = cnow.brk;
477
icount.buf_overrun = cnow.buf_overrun;
478
if (copy_to_user(user_arg, &icount, sizeof(icount)))
487
static int ark3116_tiocmget(struct tty_struct *tty, struct file *file)
489
struct usb_serial_port *port = tty->driver_data;
490
struct ark3116_private *priv = usb_get_serial_port_data(port);
495
mutex_lock(&priv->hw_lock);
497
mutex_unlock(&priv->hw_lock);
499
spin_lock_irqsave(&priv->status_lock, flags);
501
spin_unlock_irqrestore(&priv->status_lock, flags);
503
return (status & UART_MSR_DSR ? TIOCM_DSR : 0) |
504
(status & UART_MSR_CTS ? TIOCM_CTS : 0) |
505
(status & UART_MSR_RI ? TIOCM_RI : 0) |
506
(status & UART_MSR_DCD ? TIOCM_CD : 0) |
507
(ctrl & UART_MCR_DTR ? TIOCM_DTR : 0) |
508
(ctrl & UART_MCR_RTS ? TIOCM_RTS : 0) |
509
(ctrl & UART_MCR_OUT1 ? TIOCM_OUT1 : 0) |
510
(ctrl & UART_MCR_OUT2 ? TIOCM_OUT2 : 0);
513
static int ark3116_tiocmset(struct tty_struct *tty, struct file *file,
514
unsigned set, unsigned clr)
516
struct usb_serial_port *port = tty->driver_data;
517
struct ark3116_private *priv = usb_get_serial_port_data(port);
519
/* we need to take the mutex here, to make sure that the value
520
* in priv->mcr is actually the one that is in the hardware
523
mutex_lock(&priv->hw_lock);
526
priv->mcr |= UART_MCR_RTS;
528
priv->mcr |= UART_MCR_DTR;
529
if (set & TIOCM_OUT1)
530
priv->mcr |= UART_MCR_OUT1;
531
if (set & TIOCM_OUT2)
532
priv->mcr |= UART_MCR_OUT2;
534
priv->mcr &= ~UART_MCR_RTS;
536
priv->mcr &= ~UART_MCR_DTR;
537
if (clr & TIOCM_OUT1)
538
priv->mcr &= ~UART_MCR_OUT1;
539
if (clr & TIOCM_OUT2)
540
priv->mcr &= ~UART_MCR_OUT2;
542
ark3116_write_reg(port->serial, UART_MCR, priv->mcr);
544
mutex_unlock(&priv->hw_lock);
549
static void ark3116_break_ctl(struct tty_struct *tty, int break_state)
551
struct usb_serial_port *port = tty->driver_data;
552
struct ark3116_private *priv = usb_get_serial_port_data(port);
554
/* LCR is also used for other things: protect access */
555
mutex_lock(&priv->hw_lock);
558
priv->lcr |= UART_LCR_SBC;
560
priv->lcr &= ~UART_LCR_SBC;
562
ark3116_write_reg(port->serial, UART_LCR, priv->lcr);
564
mutex_unlock(&priv->hw_lock);
567
static void ark3116_update_msr(struct usb_serial_port *port, __u8 msr)
569
struct ark3116_private *priv = usb_get_serial_port_data(port);
572
spin_lock_irqsave(&priv->status_lock, flags);
574
spin_unlock_irqrestore(&priv->status_lock, flags);
576
if (msr & UART_MSR_ANY_DELTA) {
577
/* update input line counters */
578
if (msr & UART_MSR_DCTS)
580
if (msr & UART_MSR_DDSR)
582
if (msr & UART_MSR_DDCD)
584
if (msr & UART_MSR_TERI)
586
wake_up_interruptible(&priv->delta_msr_wait);
590
static void ark3116_update_lsr(struct usb_serial_port *port, __u8 lsr)
592
struct ark3116_private *priv = usb_get_serial_port_data(port);
595
spin_lock_irqsave(&priv->status_lock, flags);
598
spin_unlock_irqrestore(&priv->status_lock, flags);
600
if (lsr&UART_LSR_BRK_ERROR_BITS) {
601
if (lsr & UART_LSR_BI)
603
if (lsr & UART_LSR_FE)
604
priv->icount.frame++;
605
if (lsr & UART_LSR_PE)
606
priv->icount.parity++;
607
if (lsr & UART_LSR_OE)
608
priv->icount.overrun++;
612
static void ark3116_read_int_callback(struct urb *urb)
614
struct usb_serial_port *port = urb->context;
615
int status = urb->status;
616
const __u8 *data = urb->transfer_buffer;
623
/* this urb is terminated, clean up */
624
dbg("%s - urb shutting down with status: %d",
628
dbg("%s - nonzero urb status received: %d",
631
case 0: /* success */
632
/* discovered this by trail and error... */
633
if ((urb->actual_length == 4) && (data[0] == 0xe8)) {
634
const __u8 id = data[1]&UART_IIR_ID;
635
dbg("%s: iir=%02x", __func__, data[1]);
636
if (id == UART_IIR_MSI) {
637
dbg("%s: msr=%02x", __func__, data[3]);
638
ark3116_update_msr(port, data[3]);
640
} else if (id == UART_IIR_RLSI) {
641
dbg("%s: lsr=%02x", __func__, data[2]);
642
ark3116_update_lsr(port, data[2]);
647
* Not sure what this data meant...
649
usb_serial_debug_data(debug, &port->dev,
652
urb->transfer_buffer);
656
result = usb_submit_urb(urb, GFP_ATOMIC);
658
dev_err(&urb->dev->dev,
659
"%s - Error %d submitting interrupt urb\n",
664
/* Data comes in via the bulk (data) URB, erors/interrupts via the int URB.
665
* This means that we cannot be sure which data byte has an associated error
666
* condition, so we report an error for all data in the next bulk read.
668
* Actually, there might even be a window between the bulk data leaving the
669
* ark and reading/resetting the lsr in the read_bulk_callback where an
670
* interrupt for the next data block could come in.
671
* Without somekind of ordering on the ark, we would have to report the
672
* error for the next block of data as well...
673
* For now, let's pretend this can't happen.
675
static void ark3116_process_read_urb(struct urb *urb)
677
struct usb_serial_port *port = urb->context;
678
struct ark3116_private *priv = usb_get_serial_port_data(port);
679
struct tty_struct *tty;
680
unsigned char *data = urb->transfer_buffer;
681
char tty_flag = TTY_NORMAL;
685
/* update line status */
686
spin_lock_irqsave(&priv->status_lock, flags);
688
priv->lsr &= ~UART_LSR_BRK_ERROR_BITS;
689
spin_unlock_irqrestore(&priv->status_lock, flags);
691
if (!urb->actual_length)
694
tty = tty_port_tty_get(&port->port);
698
if (lsr & UART_LSR_BRK_ERROR_BITS) {
699
if (lsr & UART_LSR_BI)
700
tty_flag = TTY_BREAK;
701
else if (lsr & UART_LSR_PE)
702
tty_flag = TTY_PARITY;
703
else if (lsr & UART_LSR_FE)
704
tty_flag = TTY_FRAME;
706
/* overrun is special, not associated with a char */
707
if (lsr & UART_LSR_OE)
708
tty_insert_flip_char(tty, 0, TTY_OVERRUN);
710
tty_insert_flip_string_fixed_flag(tty, data, tty_flag,
712
tty_flip_buffer_push(tty);
716
static struct usb_driver ark3116_driver = {
718
.probe = usb_serial_probe,
719
.disconnect = usb_serial_disconnect,
720
.id_table = id_table,
724
static struct usb_serial_driver ark3116_device = {
726
.owner = THIS_MODULE,
729
.id_table = id_table,
730
.usb_driver = &ark3116_driver,
732
.attach = ark3116_attach,
733
.release = ark3116_release,
734
.set_termios = ark3116_set_termios,
735
.init_termios = ark3116_init_termios,
736
.ioctl = ark3116_ioctl,
737
.tiocmget = ark3116_tiocmget,
738
.tiocmset = ark3116_tiocmset,
739
.open = ark3116_open,
740
.close = ark3116_close,
741
.break_ctl = ark3116_break_ctl,
742
.read_int_callback = ark3116_read_int_callback,
743
.process_read_urb = ark3116_process_read_urb,
746
static int __init ark3116_init(void)
750
retval = usb_serial_register(&ark3116_device);
753
retval = usb_register(&ark3116_driver);
755
printk(KERN_INFO "%s:"
760
usb_serial_deregister(&ark3116_device);
764
static void __exit ark3116_exit(void)
766
usb_deregister(&ark3116_driver);
767
usb_serial_deregister(&ark3116_device);
770
module_init(ark3116_init);
771
module_exit(ark3116_exit);
772
MODULE_LICENSE("GPL");
774
MODULE_AUTHOR(DRIVER_AUTHOR);
775
MODULE_DESCRIPTION(DRIVER_DESC);
777
module_param(debug, bool, S_IRUGO | S_IWUSR);
778
MODULE_PARM_DESC(debug, "Enable debug");
781
* The following describes what I learned from studying the old
782
* ark3116.c driver, disassembling the windows driver, and some lucky
783
* guesses. Since I do not have any datasheet or other
784
* documentation, inaccuracies are almost guaranteed.
786
* Some specs for the ARK3116 can be found here:
787
* http://web.archive.org/web/20060318000438/
788
* www.arkmicro.com/en/products/view.php?id=10
789
* On that page, 2 GPIO pins are mentioned: I assume these are the
790
* OUT1 and OUT2 pins of the UART, so I added support for those
791
* through the MCR. Since the pins are not available on my hardware,
792
* I could not verify this.
793
* Also, it states there is "on-chip hardware flow control". I have
794
* discovered how to enable that. Unfortunately, I do not know how to
795
* enable XON/XOFF (software) flow control, which would need support
796
* from the chip as well to work. Because of the wording on the web
797
* page there is a real possibility the chip simply does not support
798
* software flow control.
800
* I got my ark3116 as part of a mobile phone adapter cable. On the
801
* PCB, the following numbered contacts are present:
814
* On my chip, all signals seem to be 3.3V, but 5V tolerant. But that
815
* may be different for the one you have ;-).
817
* The windows driver limits the registers to 0-F, so I assume there
818
* are actually 16 present on the device.
820
* On an UART interrupt, 4 bytes of data come in on the interrupt
821
* endpoint. The bytes are 0xe8 IIR LSR MSR.
823
* The baudrate seems to be generated from the 12MHz crystal, using
824
* 4-times subsampling. So quot=12e6/(4*baud). Also see description
828
* These seem to be the same as for a regular 16450. The FCR is set
829
* to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between
830
* the UART and the USB bridge/DMA engine.
833
* By trial and error, I found out that bit 0 enables hardware CTS,
834
* stopping TX when CTS is +5V. Bit 1 does the same for RTS, making
835
* RTS +5V when the 3116 cannot transfer the data to the USB bus
836
* (verified by disabling the reading URB). Note that as far as I can
837
* tell, the windows driver does NOT use this, so there might be some
838
* hardware bug or something.
840
* According to a patch provided here
841
* (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used
842
* as an IrDA dongle. Since I do not have such a thing, I could not
843
* investigate that aspect. However, I can speculate ;-).
845
* - IrDA encodes data differently than RS232. Most likely, one of
846
* the bits in registers 9..E enables the IR ENDEC (encoder/decoder).
847
* - Depending on the IR transceiver, the input and output need to be
848
* inverted, so there are probably bits for that as well.
849
* - IrDA is half-duplex, so there should be a bit for selecting that.
851
* This still leaves at least two registers unaccounted for. Perhaps
852
* The chip can do XON/XOFF or CRC in HW?
855
* Set to 0x00 for IrDA, when the baudrate is initialised.
858
* Set to 0x01 for IrDA, at init.
861
* Set to 0x01 for IrDA, 0x00 for RS232, at init.
864
* Set to 00 for IrDA, at init.
867
* Set to 0x41 for IrDA, at init.
870
* Somekind of baudrate override. The windows driver seems to set
871
* this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600.
872
* Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer,
873
* it could be somekind of subdivisor thingy.
874
* However,it does not seem to do anything: selecting 921600 (divisor 3,
875
* reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would
876
* work, but they don't.
878
* Register F: unknown