mmc: rtsx_pci: Enable MMC_CAP_ERASE to allow erase/discard/trim requests
[linux/fpc-iii.git] / drivers / usb / serial / ark3116.c
blob1532cde8a437b596b7ed1442aaa127666cdadb9f
1 /*
2 * Copyright (C) 2009 by Bart Hartgers (bart.hartgers+ark3116@gmail.com)
3 * Original version:
4 * Copyright (C) 2006
5 * Simon Schulz (ark3116_driver <at> auctionant.de)
7 * ark3116
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/ioctl.h>
27 #include <linux/tty.h>
28 #include <linux/slab.h>
29 #include <linux/tty_flip.h>
30 #include <linux/module.h>
31 #include <linux/usb.h>
32 #include <linux/usb/serial.h>
33 #include <linux/serial.h>
34 #include <linux/serial_reg.h>
35 #include <linux/uaccess.h>
36 #include <linux/mutex.h>
37 #include <linux/spinlock.h>
39 #define DRIVER_AUTHOR "Bart Hartgers <bart.hartgers+ark3116@gmail.com>"
40 #define DRIVER_DESC "USB ARK3116 serial/IrDA driver"
41 #define DRIVER_DEV_DESC "ARK3116 RS232/IrDA"
42 #define DRIVER_NAME "ark3116"
44 /* usb timeout of 1 second */
45 #define ARK_TIMEOUT 1000
47 static const struct usb_device_id id_table[] = {
48 { USB_DEVICE(0x6547, 0x0232) },
49 { USB_DEVICE(0x18ec, 0x3118) }, /* USB to IrDA adapter */
50 { },
52 MODULE_DEVICE_TABLE(usb, id_table);
54 static int is_irda(struct usb_serial *serial)
56 struct usb_device *dev = serial->dev;
57 if (le16_to_cpu(dev->descriptor.idVendor) == 0x18ec &&
58 le16_to_cpu(dev->descriptor.idProduct) == 0x3118)
59 return 1;
60 return 0;
63 struct ark3116_private {
64 int irda; /* 1 for irda device */
66 /* protects hw register updates */
67 struct mutex hw_lock;
69 int quot; /* baudrate divisor */
70 __u32 lcr; /* line control register value */
71 __u32 hcr; /* handshake control register (0x8)
72 * value */
73 __u32 mcr; /* modem control register value */
75 /* protects the status values below */
76 spinlock_t status_lock;
77 __u32 msr; /* modem status register value */
78 __u32 lsr; /* line status register value */
81 static int ark3116_write_reg(struct usb_serial *serial,
82 unsigned reg, __u8 val)
84 int result;
85 /* 0xfe 0x40 are magic values taken from original driver */
86 result = usb_control_msg(serial->dev,
87 usb_sndctrlpipe(serial->dev, 0),
88 0xfe, 0x40, val, reg,
89 NULL, 0, ARK_TIMEOUT);
90 return result;
93 static int ark3116_read_reg(struct usb_serial *serial,
94 unsigned reg, unsigned char *buf)
96 int result;
97 /* 0xfe 0xc0 are magic values taken from original driver */
98 result = usb_control_msg(serial->dev,
99 usb_rcvctrlpipe(serial->dev, 0),
100 0xfe, 0xc0, 0, reg,
101 buf, 1, ARK_TIMEOUT);
102 if (result < 0)
103 return result;
104 else
105 return buf[0];
108 static inline int calc_divisor(int bps)
110 /* Original ark3116 made some exceptions in rounding here
111 * because windows did the same. Assume that is not really
112 * necessary.
113 * Crystal is 12MHz, probably because of USB, but we divide by 4?
115 return (12000000 + 2*bps) / (4*bps);
118 static int ark3116_attach(struct usb_serial *serial)
120 /* make sure we have our end-points */
121 if ((serial->num_bulk_in == 0) ||
122 (serial->num_bulk_out == 0) ||
123 (serial->num_interrupt_in == 0)) {
124 dev_err(&serial->dev->dev,
125 "%s - missing endpoint - "
126 "bulk in: %d, bulk out: %d, int in %d\n",
127 KBUILD_MODNAME,
128 serial->num_bulk_in,
129 serial->num_bulk_out,
130 serial->num_interrupt_in);
131 return -EINVAL;
134 return 0;
137 static int ark3116_port_probe(struct usb_serial_port *port)
139 struct usb_serial *serial = port->serial;
140 struct ark3116_private *priv;
142 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
143 if (!priv)
144 return -ENOMEM;
146 mutex_init(&priv->hw_lock);
147 spin_lock_init(&priv->status_lock);
149 priv->irda = is_irda(serial);
151 usb_set_serial_port_data(port, priv);
153 /* setup the hardware */
154 ark3116_write_reg(serial, UART_IER, 0);
155 /* disable DMA */
156 ark3116_write_reg(serial, UART_FCR, 0);
157 /* handshake control */
158 priv->hcr = 0;
159 ark3116_write_reg(serial, 0x8 , 0);
160 /* modem control */
161 priv->mcr = 0;
162 ark3116_write_reg(serial, UART_MCR, 0);
164 if (!(priv->irda)) {
165 ark3116_write_reg(serial, 0xb , 0);
166 } else {
167 ark3116_write_reg(serial, 0xb , 1);
168 ark3116_write_reg(serial, 0xc , 0);
169 ark3116_write_reg(serial, 0xd , 0x41);
170 ark3116_write_reg(serial, 0xa , 1);
173 /* setup baudrate */
174 ark3116_write_reg(serial, UART_LCR, UART_LCR_DLAB);
176 /* setup for 9600 8N1 */
177 priv->quot = calc_divisor(9600);
178 ark3116_write_reg(serial, UART_DLL, priv->quot & 0xff);
179 ark3116_write_reg(serial, UART_DLM, (priv->quot>>8) & 0xff);
181 priv->lcr = UART_LCR_WLEN8;
182 ark3116_write_reg(serial, UART_LCR, UART_LCR_WLEN8);
184 ark3116_write_reg(serial, 0xe, 0);
186 if (priv->irda)
187 ark3116_write_reg(serial, 0x9, 0);
189 dev_info(&serial->dev->dev,
190 "%s using %s mode\n",
191 KBUILD_MODNAME,
192 priv->irda ? "IrDA" : "RS232");
193 return 0;
196 static int ark3116_port_remove(struct usb_serial_port *port)
198 struct ark3116_private *priv = usb_get_serial_port_data(port);
200 /* device is closed, so URBs and DMA should be down */
201 mutex_destroy(&priv->hw_lock);
202 kfree(priv);
204 return 0;
207 static void ark3116_init_termios(struct tty_struct *tty)
209 struct ktermios *termios = &tty->termios;
210 *termios = tty_std_termios;
211 termios->c_cflag = B9600 | CS8
212 | CREAD | HUPCL | CLOCAL;
213 termios->c_ispeed = 9600;
214 termios->c_ospeed = 9600;
217 static void ark3116_set_termios(struct tty_struct *tty,
218 struct usb_serial_port *port,
219 struct ktermios *old_termios)
221 struct usb_serial *serial = port->serial;
222 struct ark3116_private *priv = usb_get_serial_port_data(port);
223 struct ktermios *termios = &tty->termios;
224 unsigned int cflag = termios->c_cflag;
225 int bps = tty_get_baud_rate(tty);
226 int quot;
227 __u8 lcr, hcr, eval;
229 /* set data bit count */
230 switch (cflag & CSIZE) {
231 case CS5:
232 lcr = UART_LCR_WLEN5;
233 break;
234 case CS6:
235 lcr = UART_LCR_WLEN6;
236 break;
237 case CS7:
238 lcr = UART_LCR_WLEN7;
239 break;
240 default:
241 case CS8:
242 lcr = UART_LCR_WLEN8;
243 break;
245 if (cflag & CSTOPB)
246 lcr |= UART_LCR_STOP;
247 if (cflag & PARENB)
248 lcr |= UART_LCR_PARITY;
249 if (!(cflag & PARODD))
250 lcr |= UART_LCR_EPAR;
251 #ifdef CMSPAR
252 if (cflag & CMSPAR)
253 lcr |= UART_LCR_SPAR;
254 #endif
255 /* handshake control */
256 hcr = (cflag & CRTSCTS) ? 0x03 : 0x00;
258 /* calc baudrate */
259 dev_dbg(&port->dev, "%s - setting bps to %d\n", __func__, bps);
260 eval = 0;
261 switch (bps) {
262 case 0:
263 quot = calc_divisor(9600);
264 break;
265 default:
266 if ((bps < 75) || (bps > 3000000))
267 bps = 9600;
268 quot = calc_divisor(bps);
269 break;
270 case 460800:
271 eval = 1;
272 quot = calc_divisor(bps);
273 break;
274 case 921600:
275 eval = 2;
276 quot = calc_divisor(bps);
277 break;
280 /* Update state: synchronize */
281 mutex_lock(&priv->hw_lock);
283 /* keep old LCR_SBC bit */
284 lcr |= (priv->lcr & UART_LCR_SBC);
286 dev_dbg(&port->dev, "%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d\n",
287 __func__, hcr, lcr, quot);
289 /* handshake control */
290 if (priv->hcr != hcr) {
291 priv->hcr = hcr;
292 ark3116_write_reg(serial, 0x8, hcr);
295 /* baudrate */
296 if (priv->quot != quot) {
297 priv->quot = quot;
298 priv->lcr = lcr; /* need to write lcr anyway */
300 /* disable DMA since transmit/receive is
301 * shadowed by UART_DLL
303 ark3116_write_reg(serial, UART_FCR, 0);
305 ark3116_write_reg(serial, UART_LCR,
306 lcr|UART_LCR_DLAB);
307 ark3116_write_reg(serial, UART_DLL, quot & 0xff);
308 ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff);
310 /* restore lcr */
311 ark3116_write_reg(serial, UART_LCR, lcr);
312 /* magic baudrate thingy: not sure what it does,
313 * but windows does this as well.
315 ark3116_write_reg(serial, 0xe, eval);
317 /* enable DMA */
318 ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT);
319 } else if (priv->lcr != lcr) {
320 priv->lcr = lcr;
321 ark3116_write_reg(serial, UART_LCR, lcr);
324 mutex_unlock(&priv->hw_lock);
326 /* check for software flow control */
327 if (I_IXOFF(tty) || I_IXON(tty)) {
328 dev_warn(&serial->dev->dev,
329 "%s: don't know how to do software flow control\n",
330 KBUILD_MODNAME);
333 /* Don't rewrite B0 */
334 if (tty_termios_baud_rate(termios))
335 tty_termios_encode_baud_rate(termios, bps, bps);
338 static void ark3116_close(struct usb_serial_port *port)
340 struct usb_serial *serial = port->serial;
342 /* disable DMA */
343 ark3116_write_reg(serial, UART_FCR, 0);
345 /* deactivate interrupts */
346 ark3116_write_reg(serial, UART_IER, 0);
348 usb_serial_generic_close(port);
349 if (serial->num_interrupt_in)
350 usb_kill_urb(port->interrupt_in_urb);
353 static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port)
355 struct ark3116_private *priv = usb_get_serial_port_data(port);
356 struct usb_serial *serial = port->serial;
357 unsigned char *buf;
358 int result;
360 buf = kmalloc(1, GFP_KERNEL);
361 if (buf == NULL)
362 return -ENOMEM;
364 result = usb_serial_generic_open(tty, port);
365 if (result) {
366 dev_dbg(&port->dev,
367 "%s - usb_serial_generic_open failed: %d\n",
368 __func__, result);
369 goto err_out;
372 /* remove any data still left: also clears error state */
373 ark3116_read_reg(serial, UART_RX, buf);
375 /* read modem status */
376 priv->msr = ark3116_read_reg(serial, UART_MSR, buf);
377 /* read line status */
378 priv->lsr = ark3116_read_reg(serial, UART_LSR, buf);
380 result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
381 if (result) {
382 dev_err(&port->dev, "submit irq_in urb failed %d\n",
383 result);
384 ark3116_close(port);
385 goto err_out;
388 /* activate interrupts */
389 ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI);
391 /* enable DMA */
392 ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT);
394 /* setup termios */
395 if (tty)
396 ark3116_set_termios(tty, port, NULL);
398 err_out:
399 kfree(buf);
400 return result;
403 static int ark3116_ioctl(struct tty_struct *tty,
404 unsigned int cmd, unsigned long arg)
406 struct usb_serial_port *port = tty->driver_data;
407 struct serial_struct serstruct;
408 void __user *user_arg = (void __user *)arg;
410 switch (cmd) {
411 case TIOCGSERIAL:
412 /* XXX: Some of these values are probably wrong. */
413 memset(&serstruct, 0, sizeof(serstruct));
414 serstruct.type = PORT_16654;
415 serstruct.line = port->minor;
416 serstruct.port = port->port_number;
417 serstruct.custom_divisor = 0;
418 serstruct.baud_base = 460800;
420 if (copy_to_user(user_arg, &serstruct, sizeof(serstruct)))
421 return -EFAULT;
423 return 0;
424 case TIOCSSERIAL:
425 if (copy_from_user(&serstruct, user_arg, sizeof(serstruct)))
426 return -EFAULT;
427 return 0;
430 return -ENOIOCTLCMD;
433 static int ark3116_tiocmget(struct tty_struct *tty)
435 struct usb_serial_port *port = tty->driver_data;
436 struct ark3116_private *priv = usb_get_serial_port_data(port);
437 __u32 status;
438 __u32 ctrl;
439 unsigned long flags;
441 mutex_lock(&priv->hw_lock);
442 ctrl = priv->mcr;
443 mutex_unlock(&priv->hw_lock);
445 spin_lock_irqsave(&priv->status_lock, flags);
446 status = priv->msr;
447 spin_unlock_irqrestore(&priv->status_lock, flags);
449 return (status & UART_MSR_DSR ? TIOCM_DSR : 0) |
450 (status & UART_MSR_CTS ? TIOCM_CTS : 0) |
451 (status & UART_MSR_RI ? TIOCM_RI : 0) |
452 (status & UART_MSR_DCD ? TIOCM_CD : 0) |
453 (ctrl & UART_MCR_DTR ? TIOCM_DTR : 0) |
454 (ctrl & UART_MCR_RTS ? TIOCM_RTS : 0) |
455 (ctrl & UART_MCR_OUT1 ? TIOCM_OUT1 : 0) |
456 (ctrl & UART_MCR_OUT2 ? TIOCM_OUT2 : 0);
459 static int ark3116_tiocmset(struct tty_struct *tty,
460 unsigned set, unsigned clr)
462 struct usb_serial_port *port = tty->driver_data;
463 struct ark3116_private *priv = usb_get_serial_port_data(port);
465 /* we need to take the mutex here, to make sure that the value
466 * in priv->mcr is actually the one that is in the hardware
469 mutex_lock(&priv->hw_lock);
471 if (set & TIOCM_RTS)
472 priv->mcr |= UART_MCR_RTS;
473 if (set & TIOCM_DTR)
474 priv->mcr |= UART_MCR_DTR;
475 if (set & TIOCM_OUT1)
476 priv->mcr |= UART_MCR_OUT1;
477 if (set & TIOCM_OUT2)
478 priv->mcr |= UART_MCR_OUT2;
479 if (clr & TIOCM_RTS)
480 priv->mcr &= ~UART_MCR_RTS;
481 if (clr & TIOCM_DTR)
482 priv->mcr &= ~UART_MCR_DTR;
483 if (clr & TIOCM_OUT1)
484 priv->mcr &= ~UART_MCR_OUT1;
485 if (clr & TIOCM_OUT2)
486 priv->mcr &= ~UART_MCR_OUT2;
488 ark3116_write_reg(port->serial, UART_MCR, priv->mcr);
490 mutex_unlock(&priv->hw_lock);
492 return 0;
495 static void ark3116_break_ctl(struct tty_struct *tty, int break_state)
497 struct usb_serial_port *port = tty->driver_data;
498 struct ark3116_private *priv = usb_get_serial_port_data(port);
500 /* LCR is also used for other things: protect access */
501 mutex_lock(&priv->hw_lock);
503 if (break_state)
504 priv->lcr |= UART_LCR_SBC;
505 else
506 priv->lcr &= ~UART_LCR_SBC;
508 ark3116_write_reg(port->serial, UART_LCR, priv->lcr);
510 mutex_unlock(&priv->hw_lock);
513 static void ark3116_update_msr(struct usb_serial_port *port, __u8 msr)
515 struct ark3116_private *priv = usb_get_serial_port_data(port);
516 unsigned long flags;
518 spin_lock_irqsave(&priv->status_lock, flags);
519 priv->msr = msr;
520 spin_unlock_irqrestore(&priv->status_lock, flags);
522 if (msr & UART_MSR_ANY_DELTA) {
523 /* update input line counters */
524 if (msr & UART_MSR_DCTS)
525 port->icount.cts++;
526 if (msr & UART_MSR_DDSR)
527 port->icount.dsr++;
528 if (msr & UART_MSR_DDCD)
529 port->icount.dcd++;
530 if (msr & UART_MSR_TERI)
531 port->icount.rng++;
532 wake_up_interruptible(&port->port.delta_msr_wait);
536 static void ark3116_update_lsr(struct usb_serial_port *port, __u8 lsr)
538 struct ark3116_private *priv = usb_get_serial_port_data(port);
539 unsigned long flags;
541 spin_lock_irqsave(&priv->status_lock, flags);
542 /* combine bits */
543 priv->lsr |= lsr;
544 spin_unlock_irqrestore(&priv->status_lock, flags);
546 if (lsr&UART_LSR_BRK_ERROR_BITS) {
547 if (lsr & UART_LSR_BI)
548 port->icount.brk++;
549 if (lsr & UART_LSR_FE)
550 port->icount.frame++;
551 if (lsr & UART_LSR_PE)
552 port->icount.parity++;
553 if (lsr & UART_LSR_OE)
554 port->icount.overrun++;
558 static void ark3116_read_int_callback(struct urb *urb)
560 struct usb_serial_port *port = urb->context;
561 int status = urb->status;
562 const __u8 *data = urb->transfer_buffer;
563 int result;
565 switch (status) {
566 case -ECONNRESET:
567 case -ENOENT:
568 case -ESHUTDOWN:
569 /* this urb is terminated, clean up */
570 dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
571 __func__, status);
572 return;
573 default:
574 dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
575 __func__, status);
576 break;
577 case 0: /* success */
578 /* discovered this by trail and error... */
579 if ((urb->actual_length == 4) && (data[0] == 0xe8)) {
580 const __u8 id = data[1]&UART_IIR_ID;
581 dev_dbg(&port->dev, "%s: iir=%02x\n", __func__, data[1]);
582 if (id == UART_IIR_MSI) {
583 dev_dbg(&port->dev, "%s: msr=%02x\n",
584 __func__, data[3]);
585 ark3116_update_msr(port, data[3]);
586 break;
587 } else if (id == UART_IIR_RLSI) {
588 dev_dbg(&port->dev, "%s: lsr=%02x\n",
589 __func__, data[2]);
590 ark3116_update_lsr(port, data[2]);
591 break;
595 * Not sure what this data meant...
597 usb_serial_debug_data(&port->dev, __func__,
598 urb->actual_length,
599 urb->transfer_buffer);
600 break;
603 result = usb_submit_urb(urb, GFP_ATOMIC);
604 if (result)
605 dev_err(&urb->dev->dev,
606 "%s - Error %d submitting interrupt urb\n",
607 __func__, result);
611 /* Data comes in via the bulk (data) URB, errors/interrupts via the int URB.
612 * This means that we cannot be sure which data byte has an associated error
613 * condition, so we report an error for all data in the next bulk read.
615 * Actually, there might even be a window between the bulk data leaving the
616 * ark and reading/resetting the lsr in the read_bulk_callback where an
617 * interrupt for the next data block could come in.
618 * Without somekind of ordering on the ark, we would have to report the
619 * error for the next block of data as well...
620 * For now, let's pretend this can't happen.
622 static void ark3116_process_read_urb(struct urb *urb)
624 struct usb_serial_port *port = urb->context;
625 struct ark3116_private *priv = usb_get_serial_port_data(port);
626 unsigned char *data = urb->transfer_buffer;
627 char tty_flag = TTY_NORMAL;
628 unsigned long flags;
629 __u32 lsr;
631 /* update line status */
632 spin_lock_irqsave(&priv->status_lock, flags);
633 lsr = priv->lsr;
634 priv->lsr &= ~UART_LSR_BRK_ERROR_BITS;
635 spin_unlock_irqrestore(&priv->status_lock, flags);
637 if (!urb->actual_length)
638 return;
640 if (lsr & UART_LSR_BRK_ERROR_BITS) {
641 if (lsr & UART_LSR_BI)
642 tty_flag = TTY_BREAK;
643 else if (lsr & UART_LSR_PE)
644 tty_flag = TTY_PARITY;
645 else if (lsr & UART_LSR_FE)
646 tty_flag = TTY_FRAME;
648 /* overrun is special, not associated with a char */
649 if (lsr & UART_LSR_OE)
650 tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
652 tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag,
653 urb->actual_length);
654 tty_flip_buffer_push(&port->port);
657 static struct usb_serial_driver ark3116_device = {
658 .driver = {
659 .owner = THIS_MODULE,
660 .name = "ark3116",
662 .id_table = id_table,
663 .num_ports = 1,
664 .attach = ark3116_attach,
665 .port_probe = ark3116_port_probe,
666 .port_remove = ark3116_port_remove,
667 .set_termios = ark3116_set_termios,
668 .init_termios = ark3116_init_termios,
669 .ioctl = ark3116_ioctl,
670 .tiocmget = ark3116_tiocmget,
671 .tiocmset = ark3116_tiocmset,
672 .tiocmiwait = usb_serial_generic_tiocmiwait,
673 .get_icount = usb_serial_generic_get_icount,
674 .open = ark3116_open,
675 .close = ark3116_close,
676 .break_ctl = ark3116_break_ctl,
677 .read_int_callback = ark3116_read_int_callback,
678 .process_read_urb = ark3116_process_read_urb,
681 static struct usb_serial_driver * const serial_drivers[] = {
682 &ark3116_device, NULL
685 module_usb_serial_driver(serial_drivers, id_table);
687 MODULE_LICENSE("GPL");
689 MODULE_AUTHOR(DRIVER_AUTHOR);
690 MODULE_DESCRIPTION(DRIVER_DESC);
693 * The following describes what I learned from studying the old
694 * ark3116.c driver, disassembling the windows driver, and some lucky
695 * guesses. Since I do not have any datasheet or other
696 * documentation, inaccuracies are almost guaranteed.
698 * Some specs for the ARK3116 can be found here:
699 * http://web.archive.org/web/20060318000438/
700 * www.arkmicro.com/en/products/view.php?id=10
701 * On that page, 2 GPIO pins are mentioned: I assume these are the
702 * OUT1 and OUT2 pins of the UART, so I added support for those
703 * through the MCR. Since the pins are not available on my hardware,
704 * I could not verify this.
705 * Also, it states there is "on-chip hardware flow control". I have
706 * discovered how to enable that. Unfortunately, I do not know how to
707 * enable XON/XOFF (software) flow control, which would need support
708 * from the chip as well to work. Because of the wording on the web
709 * page there is a real possibility the chip simply does not support
710 * software flow control.
712 * I got my ark3116 as part of a mobile phone adapter cable. On the
713 * PCB, the following numbered contacts are present:
715 * 1:- +5V
716 * 2:o DTR
717 * 3:i RX
718 * 4:i DCD
719 * 5:o RTS
720 * 6:o TX
721 * 7:i RI
722 * 8:i DSR
723 * 10:- 0V
724 * 11:i CTS
726 * On my chip, all signals seem to be 3.3V, but 5V tolerant. But that
727 * may be different for the one you have ;-).
729 * The windows driver limits the registers to 0-F, so I assume there
730 * are actually 16 present on the device.
732 * On an UART interrupt, 4 bytes of data come in on the interrupt
733 * endpoint. The bytes are 0xe8 IIR LSR MSR.
735 * The baudrate seems to be generated from the 12MHz crystal, using
736 * 4-times subsampling. So quot=12e6/(4*baud). Also see description
737 * of register E.
739 * Registers 0-7:
740 * These seem to be the same as for a regular 16450. The FCR is set
741 * to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between
742 * the UART and the USB bridge/DMA engine.
744 * Register 8:
745 * By trial and error, I found out that bit 0 enables hardware CTS,
746 * stopping TX when CTS is +5V. Bit 1 does the same for RTS, making
747 * RTS +5V when the 3116 cannot transfer the data to the USB bus
748 * (verified by disabling the reading URB). Note that as far as I can
749 * tell, the windows driver does NOT use this, so there might be some
750 * hardware bug or something.
752 * According to a patch provided here
753 * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used
754 * as an IrDA dongle. Since I do not have such a thing, I could not
755 * investigate that aspect. However, I can speculate ;-).
757 * - IrDA encodes data differently than RS232. Most likely, one of
758 * the bits in registers 9..E enables the IR ENDEC (encoder/decoder).
759 * - Depending on the IR transceiver, the input and output need to be
760 * inverted, so there are probably bits for that as well.
761 * - IrDA is half-duplex, so there should be a bit for selecting that.
763 * This still leaves at least two registers unaccounted for. Perhaps
764 * The chip can do XON/XOFF or CRC in HW?
766 * Register 9:
767 * Set to 0x00 for IrDA, when the baudrate is initialised.
769 * Register A:
770 * Set to 0x01 for IrDA, at init.
772 * Register B:
773 * Set to 0x01 for IrDA, 0x00 for RS232, at init.
775 * Register C:
776 * Set to 00 for IrDA, at init.
778 * Register D:
779 * Set to 0x41 for IrDA, at init.
781 * Register E:
782 * Somekind of baudrate override. The windows driver seems to set
783 * this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600.
784 * Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer,
785 * it could be somekind of subdivisor thingy.
786 * However,it does not seem to do anything: selecting 921600 (divisor 3,
787 * reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would
788 * work, but they don't.
790 * Register F: unknown