1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Copyright (C) 2009 by Bart Hartgers (bart.hartgers+ark3116@gmail.com) 4 * Original version: 5 * Copyright (C) 2006 6 * Simon Schulz (ark3116_driver <at> auctionant.de) 7 * 8 * ark3116 9 * - implements a driver for the arkmicro ark3116 chipset (vendor=0x6547, 10 * productid=0x0232) (used in a datacable called KQ-U8A) 11 * 12 * Supports full modem status lines, break, hardware flow control. Does not 13 * support software flow control, since I do not know how to enable it in hw. 14 * 15 * This driver is a essentially new implementation. I initially dug 16 * into the old ark3116.c driver and suddenly realized the ark3116 is 17 * a 16450 with a USB interface glued to it. See comments at the 18 * bottom of this file. 19 */ 20 21 #include <linux/kernel.h> 22 #include <linux/ioctl.h> 23 #include <linux/tty.h> 24 #include <linux/slab.h> 25 #include <linux/tty_flip.h> 26 #include <linux/module.h> 27 #include <linux/usb.h> 28 #include <linux/usb/serial.h> 29 #include <linux/serial.h> 30 #include <linux/serial_reg.h> 31 #include <linux/uaccess.h> 32 #include <linux/mutex.h> 33 #include <linux/spinlock.h> 34 35 #define DRIVER_AUTHOR "Bart Hartgers <bart.hartgers+ark3116@gmail.com>" 36 #define DRIVER_DESC "USB ARK3116 serial/IrDA driver" 37 #define DRIVER_DEV_DESC "ARK3116 RS232/IrDA" 38 #define DRIVER_NAME "ark3116" 39 40 /* usb timeout of 1 second */ 41 #define ARK_TIMEOUT 1000 42 43 static const struct usb_device_id id_table[] = { 44 { USB_DEVICE(0x6547, 0x0232) }, 45 { USB_DEVICE(0x18ec, 0x3118) }, /* USB to IrDA adapter */ 46 { }, 47 }; 48 MODULE_DEVICE_TABLE(usb, id_table); 49 50 static int is_irda(struct usb_serial *serial) 51 { 52 struct usb_device *dev = serial->dev; 53 if (le16_to_cpu(dev->descriptor.idVendor) == 0x18ec && 54 le16_to_cpu(dev->descriptor.idProduct) == 0x3118) 55 return 1; 56 return 0; 57 } 58 59 struct ark3116_private { 60 int irda; /* 1 for irda device */ 61 62 /* protects hw register updates */ 63 struct mutex hw_lock; 64 65 int quot; /* baudrate divisor */ 66 __u32 lcr; /* line control register value */ 67 __u32 hcr; /* handshake control register (0x8) 68 * value */ 69 __u32 mcr; /* modem control register value */ 70 71 /* protects the status values below */ 72 spinlock_t status_lock; 73 __u32 msr; /* modem status register value */ 74 __u32 lsr; /* line status register value */ 75 }; 76 77 static int ark3116_write_reg(struct usb_serial *serial, 78 unsigned reg, __u8 val) 79 { 80 int result; 81 /* 0xfe 0x40 are magic values taken from original driver */ 82 result = usb_control_msg(serial->dev, 83 usb_sndctrlpipe(serial->dev, 0), 84 0xfe, 0x40, val, reg, 85 NULL, 0, ARK_TIMEOUT); 86 if (result) 87 return result; 88 89 return 0; 90 } 91 92 static int ark3116_read_reg(struct usb_serial *serial, 93 unsigned reg, unsigned char *buf) 94 { 95 int result; 96 /* 0xfe 0xc0 are magic values taken from original driver */ 97 result = usb_control_msg(serial->dev, 98 usb_rcvctrlpipe(serial->dev, 0), 99 0xfe, 0xc0, 0, reg, 100 buf, 1, ARK_TIMEOUT); 101 if (result < 1) { 102 dev_err(&serial->interface->dev, 103 "failed to read register %u: %d\n", 104 reg, result); 105 if (result >= 0) 106 result = -EIO; 107 108 return result; 109 } 110 111 return 0; 112 } 113 114 static inline int calc_divisor(int bps) 115 { 116 /* Original ark3116 made some exceptions in rounding here 117 * because windows did the same. Assume that is not really 118 * necessary. 119 * Crystal is 12MHz, probably because of USB, but we divide by 4? 120 */ 121 return (12000000 + 2*bps) / (4*bps); 122 } 123 124 static int ark3116_port_probe(struct usb_serial_port *port) 125 { 126 struct usb_serial *serial = port->serial; 127 struct ark3116_private *priv; 128 129 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 130 if (!priv) 131 return -ENOMEM; 132 133 mutex_init(&priv->hw_lock); 134 spin_lock_init(&priv->status_lock); 135 136 priv->irda = is_irda(serial); 137 138 usb_set_serial_port_data(port, priv); 139 140 /* setup the hardware */ 141 ark3116_write_reg(serial, UART_IER, 0); 142 /* disable DMA */ 143 ark3116_write_reg(serial, UART_FCR, 0); 144 /* handshake control */ 145 priv->hcr = 0; 146 ark3116_write_reg(serial, 0x8 , 0); 147 /* modem control */ 148 priv->mcr = 0; 149 ark3116_write_reg(serial, UART_MCR, 0); 150 151 if (!(priv->irda)) { 152 ark3116_write_reg(serial, 0xb , 0); 153 } else { 154 ark3116_write_reg(serial, 0xb , 1); 155 ark3116_write_reg(serial, 0xc , 0); 156 ark3116_write_reg(serial, 0xd , 0x41); 157 ark3116_write_reg(serial, 0xa , 1); 158 } 159 160 /* setup baudrate */ 161 ark3116_write_reg(serial, UART_LCR, UART_LCR_DLAB); 162 163 /* setup for 9600 8N1 */ 164 priv->quot = calc_divisor(9600); 165 ark3116_write_reg(serial, UART_DLL, priv->quot & 0xff); 166 ark3116_write_reg(serial, UART_DLM, (priv->quot>>8) & 0xff); 167 168 priv->lcr = UART_LCR_WLEN8; 169 ark3116_write_reg(serial, UART_LCR, UART_LCR_WLEN8); 170 171 ark3116_write_reg(serial, 0xe, 0); 172 173 if (priv->irda) 174 ark3116_write_reg(serial, 0x9, 0); 175 176 dev_info(&port->dev, "using %s mode\n", priv->irda ? "IrDA" : "RS232"); 177 178 return 0; 179 } 180 181 static int ark3116_port_remove(struct usb_serial_port *port) 182 { 183 struct ark3116_private *priv = usb_get_serial_port_data(port); 184 185 /* device is closed, so URBs and DMA should be down */ 186 mutex_destroy(&priv->hw_lock); 187 kfree(priv); 188 189 return 0; 190 } 191 192 static void ark3116_init_termios(struct tty_struct *tty) 193 { 194 struct ktermios *termios = &tty->termios; 195 *termios = tty_std_termios; 196 termios->c_cflag = B9600 | CS8 197 | CREAD | HUPCL | CLOCAL; 198 termios->c_ispeed = 9600; 199 termios->c_ospeed = 9600; 200 } 201 202 static void ark3116_set_termios(struct tty_struct *tty, 203 struct usb_serial_port *port, 204 struct ktermios *old_termios) 205 { 206 struct usb_serial *serial = port->serial; 207 struct ark3116_private *priv = usb_get_serial_port_data(port); 208 struct ktermios *termios = &tty->termios; 209 unsigned int cflag = termios->c_cflag; 210 int bps = tty_get_baud_rate(tty); 211 int quot; 212 __u8 lcr, hcr, eval; 213 214 /* set data bit count */ 215 switch (cflag & CSIZE) { 216 case CS5: 217 lcr = UART_LCR_WLEN5; 218 break; 219 case CS6: 220 lcr = UART_LCR_WLEN6; 221 break; 222 case CS7: 223 lcr = UART_LCR_WLEN7; 224 break; 225 default: 226 case CS8: 227 lcr = UART_LCR_WLEN8; 228 break; 229 } 230 if (cflag & CSTOPB) 231 lcr |= UART_LCR_STOP; 232 if (cflag & PARENB) 233 lcr |= UART_LCR_PARITY; 234 if (!(cflag & PARODD)) 235 lcr |= UART_LCR_EPAR; 236 #ifdef CMSPAR 237 if (cflag & CMSPAR) 238 lcr |= UART_LCR_SPAR; 239 #endif 240 /* handshake control */ 241 hcr = (cflag & CRTSCTS) ? 0x03 : 0x00; 242 243 /* calc baudrate */ 244 dev_dbg(&port->dev, "%s - setting bps to %d\n", __func__, bps); 245 eval = 0; 246 switch (bps) { 247 case 0: 248 quot = calc_divisor(9600); 249 break; 250 default: 251 if ((bps < 75) || (bps > 3000000)) 252 bps = 9600; 253 quot = calc_divisor(bps); 254 break; 255 case 460800: 256 eval = 1; 257 quot = calc_divisor(bps); 258 break; 259 case 921600: 260 eval = 2; 261 quot = calc_divisor(bps); 262 break; 263 } 264 265 /* Update state: synchronize */ 266 mutex_lock(&priv->hw_lock); 267 268 /* keep old LCR_SBC bit */ 269 lcr |= (priv->lcr & UART_LCR_SBC); 270 271 dev_dbg(&port->dev, "%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d\n", 272 __func__, hcr, lcr, quot); 273 274 /* handshake control */ 275 if (priv->hcr != hcr) { 276 priv->hcr = hcr; 277 ark3116_write_reg(serial, 0x8, hcr); 278 } 279 280 /* baudrate */ 281 if (priv->quot != quot) { 282 priv->quot = quot; 283 priv->lcr = lcr; /* need to write lcr anyway */ 284 285 /* disable DMA since transmit/receive is 286 * shadowed by UART_DLL 287 */ 288 ark3116_write_reg(serial, UART_FCR, 0); 289 290 ark3116_write_reg(serial, UART_LCR, 291 lcr|UART_LCR_DLAB); 292 ark3116_write_reg(serial, UART_DLL, quot & 0xff); 293 ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff); 294 295 /* restore lcr */ 296 ark3116_write_reg(serial, UART_LCR, lcr); 297 /* magic baudrate thingy: not sure what it does, 298 * but windows does this as well. 299 */ 300 ark3116_write_reg(serial, 0xe, eval); 301 302 /* enable DMA */ 303 ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT); 304 } else if (priv->lcr != lcr) { 305 priv->lcr = lcr; 306 ark3116_write_reg(serial, UART_LCR, lcr); 307 } 308 309 mutex_unlock(&priv->hw_lock); 310 311 /* check for software flow control */ 312 if (I_IXOFF(tty) || I_IXON(tty)) { 313 dev_warn(&port->dev, 314 "software flow control not implemented\n"); 315 } 316 317 /* Don't rewrite B0 */ 318 if (tty_termios_baud_rate(termios)) 319 tty_termios_encode_baud_rate(termios, bps, bps); 320 } 321 322 static void ark3116_close(struct usb_serial_port *port) 323 { 324 struct usb_serial *serial = port->serial; 325 326 /* disable DMA */ 327 ark3116_write_reg(serial, UART_FCR, 0); 328 329 /* deactivate interrupts */ 330 ark3116_write_reg(serial, UART_IER, 0); 331 332 usb_serial_generic_close(port); 333 334 usb_kill_urb(port->interrupt_in_urb); 335 } 336 337 static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port) 338 { 339 struct ark3116_private *priv = usb_get_serial_port_data(port); 340 struct usb_serial *serial = port->serial; 341 unsigned char *buf; 342 int result; 343 344 buf = kmalloc(1, GFP_KERNEL); 345 if (buf == NULL) 346 return -ENOMEM; 347 348 result = usb_serial_generic_open(tty, port); 349 if (result) { 350 dev_dbg(&port->dev, 351 "%s - usb_serial_generic_open failed: %d\n", 352 __func__, result); 353 goto err_free; 354 } 355 356 /* remove any data still left: also clears error state */ 357 ark3116_read_reg(serial, UART_RX, buf); 358 359 /* read modem status */ 360 result = ark3116_read_reg(serial, UART_MSR, buf); 361 if (result) 362 goto err_close; 363 priv->msr = *buf; 364 365 /* read line status */ 366 result = ark3116_read_reg(serial, UART_LSR, buf); 367 if (result) 368 goto err_close; 369 priv->lsr = *buf; 370 371 result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL); 372 if (result) { 373 dev_err(&port->dev, "submit irq_in urb failed %d\n", 374 result); 375 goto err_close; 376 } 377 378 /* activate interrupts */ 379 ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI); 380 381 /* enable DMA */ 382 ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT); 383 384 /* setup termios */ 385 if (tty) 386 ark3116_set_termios(tty, port, NULL); 387 388 kfree(buf); 389 390 return 0; 391 392 err_close: 393 usb_serial_generic_close(port); 394 err_free: 395 kfree(buf); 396 397 return result; 398 } 399 400 static int ark3116_get_serial_info(struct usb_serial_port *port, 401 struct serial_struct __user *retinfo) 402 { 403 struct serial_struct tmp; 404 405 memset(&tmp, 0, sizeof(tmp)); 406 407 tmp.type = PORT_16654; 408 tmp.line = port->minor; 409 tmp.port = port->port_number; 410 tmp.baud_base = 460800; 411 412 if (copy_to_user(retinfo, &tmp, sizeof(tmp))) 413 return -EFAULT; 414 415 return 0; 416 } 417 418 static int ark3116_ioctl(struct tty_struct *tty, 419 unsigned int cmd, unsigned long arg) 420 { 421 struct usb_serial_port *port = tty->driver_data; 422 void __user *user_arg = (void __user *)arg; 423 424 switch (cmd) { 425 case TIOCGSERIAL: 426 return ark3116_get_serial_info(port, user_arg); 427 default: 428 break; 429 } 430 431 return -ENOIOCTLCMD; 432 } 433 434 static int ark3116_tiocmget(struct tty_struct *tty) 435 { 436 struct usb_serial_port *port = tty->driver_data; 437 struct ark3116_private *priv = usb_get_serial_port_data(port); 438 __u32 status; 439 __u32 ctrl; 440 unsigned long flags; 441 442 mutex_lock(&priv->hw_lock); 443 ctrl = priv->mcr; 444 mutex_unlock(&priv->hw_lock); 445 446 spin_lock_irqsave(&priv->status_lock, flags); 447 status = priv->msr; 448 spin_unlock_irqrestore(&priv->status_lock, flags); 449 450 return (status & UART_MSR_DSR ? TIOCM_DSR : 0) | 451 (status & UART_MSR_CTS ? TIOCM_CTS : 0) | 452 (status & UART_MSR_RI ? TIOCM_RI : 0) | 453 (status & UART_MSR_DCD ? TIOCM_CD : 0) | 454 (ctrl & UART_MCR_DTR ? TIOCM_DTR : 0) | 455 (ctrl & UART_MCR_RTS ? TIOCM_RTS : 0) | 456 (ctrl & UART_MCR_OUT1 ? TIOCM_OUT1 : 0) | 457 (ctrl & UART_MCR_OUT2 ? TIOCM_OUT2 : 0); 458 } 459 460 static int ark3116_tiocmset(struct tty_struct *tty, 461 unsigned set, unsigned clr) 462 { 463 struct usb_serial_port *port = tty->driver_data; 464 struct ark3116_private *priv = usb_get_serial_port_data(port); 465 466 /* we need to take the mutex here, to make sure that the value 467 * in priv->mcr is actually the one that is in the hardware 468 */ 469 470 mutex_lock(&priv->hw_lock); 471 472 if (set & TIOCM_RTS) 473 priv->mcr |= UART_MCR_RTS; 474 if (set & TIOCM_DTR) 475 priv->mcr |= UART_MCR_DTR; 476 if (set & TIOCM_OUT1) 477 priv->mcr |= UART_MCR_OUT1; 478 if (set & TIOCM_OUT2) 479 priv->mcr |= UART_MCR_OUT2; 480 if (clr & TIOCM_RTS) 481 priv->mcr &= ~UART_MCR_RTS; 482 if (clr & TIOCM_DTR) 483 priv->mcr &= ~UART_MCR_DTR; 484 if (clr & TIOCM_OUT1) 485 priv->mcr &= ~UART_MCR_OUT1; 486 if (clr & TIOCM_OUT2) 487 priv->mcr &= ~UART_MCR_OUT2; 488 489 ark3116_write_reg(port->serial, UART_MCR, priv->mcr); 490 491 mutex_unlock(&priv->hw_lock); 492 493 return 0; 494 } 495 496 static void ark3116_break_ctl(struct tty_struct *tty, int break_state) 497 { 498 struct usb_serial_port *port = tty->driver_data; 499 struct ark3116_private *priv = usb_get_serial_port_data(port); 500 501 /* LCR is also used for other things: protect access */ 502 mutex_lock(&priv->hw_lock); 503 504 if (break_state) 505 priv->lcr |= UART_LCR_SBC; 506 else 507 priv->lcr &= ~UART_LCR_SBC; 508 509 ark3116_write_reg(port->serial, UART_LCR, priv->lcr); 510 511 mutex_unlock(&priv->hw_lock); 512 } 513 514 static void ark3116_update_msr(struct usb_serial_port *port, __u8 msr) 515 { 516 struct ark3116_private *priv = usb_get_serial_port_data(port); 517 unsigned long flags; 518 519 spin_lock_irqsave(&priv->status_lock, flags); 520 priv->msr = msr; 521 spin_unlock_irqrestore(&priv->status_lock, flags); 522 523 if (msr & UART_MSR_ANY_DELTA) { 524 /* update input line counters */ 525 if (msr & UART_MSR_DCTS) 526 port->icount.cts++; 527 if (msr & UART_MSR_DDSR) 528 port->icount.dsr++; 529 if (msr & UART_MSR_DDCD) 530 port->icount.dcd++; 531 if (msr & UART_MSR_TERI) 532 port->icount.rng++; 533 wake_up_interruptible(&port->port.delta_msr_wait); 534 } 535 } 536 537 static void ark3116_update_lsr(struct usb_serial_port *port, __u8 lsr) 538 { 539 struct ark3116_private *priv = usb_get_serial_port_data(port); 540 unsigned long flags; 541 542 spin_lock_irqsave(&priv->status_lock, flags); 543 /* combine bits */ 544 priv->lsr |= lsr; 545 spin_unlock_irqrestore(&priv->status_lock, flags); 546 547 if (lsr&UART_LSR_BRK_ERROR_BITS) { 548 if (lsr & UART_LSR_BI) 549 port->icount.brk++; 550 if (lsr & UART_LSR_FE) 551 port->icount.frame++; 552 if (lsr & UART_LSR_PE) 553 port->icount.parity++; 554 if (lsr & UART_LSR_OE) 555 port->icount.overrun++; 556 } 557 } 558 559 static void ark3116_read_int_callback(struct urb *urb) 560 { 561 struct usb_serial_port *port = urb->context; 562 int status = urb->status; 563 const __u8 *data = urb->transfer_buffer; 564 int result; 565 566 switch (status) { 567 case -ECONNRESET: 568 case -ENOENT: 569 case -ESHUTDOWN: 570 /* this urb is terminated, clean up */ 571 dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n", 572 __func__, status); 573 return; 574 default: 575 dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n", 576 __func__, status); 577 break; 578 case 0: /* success */ 579 /* discovered this by trail and error... */ 580 if ((urb->actual_length == 4) && (data[0] == 0xe8)) { 581 const __u8 id = data[1]&UART_IIR_ID; 582 dev_dbg(&port->dev, "%s: iir=%02x\n", __func__, data[1]); 583 if (id == UART_IIR_MSI) { 584 dev_dbg(&port->dev, "%s: msr=%02x\n", 585 __func__, data[3]); 586 ark3116_update_msr(port, data[3]); 587 break; 588 } else if (id == UART_IIR_RLSI) { 589 dev_dbg(&port->dev, "%s: lsr=%02x\n", 590 __func__, data[2]); 591 ark3116_update_lsr(port, data[2]); 592 break; 593 } 594 } 595 /* 596 * Not sure what this data meant... 597 */ 598 usb_serial_debug_data(&port->dev, __func__, 599 urb->actual_length, 600 urb->transfer_buffer); 601 break; 602 } 603 604 result = usb_submit_urb(urb, GFP_ATOMIC); 605 if (result) 606 dev_err(&port->dev, "failed to resubmit interrupt urb: %d\n", 607 result); 608 } 609 610 611 /* 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. 614 * 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. 621 */ 622 static void ark3116_process_read_urb(struct urb *urb) 623 { 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; 630 631 /* 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); 636 637 if (!urb->actual_length) 638 return; 639 640 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; 647 648 /* overrun is special, not associated with a char */ 649 if (lsr & UART_LSR_OE) 650 tty_insert_flip_char(&port->port, 0, TTY_OVERRUN); 651 } 652 tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag, 653 urb->actual_length); 654 tty_flip_buffer_push(&port->port); 655 } 656 657 static struct usb_serial_driver ark3116_device = { 658 .driver = { 659 .owner = THIS_MODULE, 660 .name = "ark3116", 661 }, 662 .id_table = id_table, 663 .num_ports = 1, 664 .num_bulk_in = 1, 665 .num_bulk_out = 1, 666 .num_interrupt_in = 1, 667 .port_probe = ark3116_port_probe, 668 .port_remove = ark3116_port_remove, 669 .set_termios = ark3116_set_termios, 670 .init_termios = ark3116_init_termios, 671 .ioctl = ark3116_ioctl, 672 .tiocmget = ark3116_tiocmget, 673 .tiocmset = ark3116_tiocmset, 674 .tiocmiwait = usb_serial_generic_tiocmiwait, 675 .get_icount = usb_serial_generic_get_icount, 676 .open = ark3116_open, 677 .close = ark3116_close, 678 .break_ctl = ark3116_break_ctl, 679 .read_int_callback = ark3116_read_int_callback, 680 .process_read_urb = ark3116_process_read_urb, 681 }; 682 683 static struct usb_serial_driver * const serial_drivers[] = { 684 &ark3116_device, NULL 685 }; 686 687 module_usb_serial_driver(serial_drivers, id_table); 688 689 MODULE_LICENSE("GPL"); 690 691 MODULE_AUTHOR(DRIVER_AUTHOR); 692 MODULE_DESCRIPTION(DRIVER_DESC); 693 694 /* 695 * The following describes what I learned from studying the old 696 * ark3116.c driver, disassembling the windows driver, and some lucky 697 * guesses. Since I do not have any datasheet or other 698 * documentation, inaccuracies are almost guaranteed. 699 * 700 * Some specs for the ARK3116 can be found here: 701 * http://web.archive.org/web/20060318000438/ 702 * www.arkmicro.com/en/products/view.php?id=10 703 * On that page, 2 GPIO pins are mentioned: I assume these are the 704 * OUT1 and OUT2 pins of the UART, so I added support for those 705 * through the MCR. Since the pins are not available on my hardware, 706 * I could not verify this. 707 * Also, it states there is "on-chip hardware flow control". I have 708 * discovered how to enable that. Unfortunately, I do not know how to 709 * enable XON/XOFF (software) flow control, which would need support 710 * from the chip as well to work. Because of the wording on the web 711 * page there is a real possibility the chip simply does not support 712 * software flow control. 713 * 714 * I got my ark3116 as part of a mobile phone adapter cable. On the 715 * PCB, the following numbered contacts are present: 716 * 717 * 1:- +5V 718 * 2:o DTR 719 * 3:i RX 720 * 4:i DCD 721 * 5:o RTS 722 * 6:o TX 723 * 7:i RI 724 * 8:i DSR 725 * 10:- 0V 726 * 11:i CTS 727 * 728 * On my chip, all signals seem to be 3.3V, but 5V tolerant. But that 729 * may be different for the one you have ;-). 730 * 731 * The windows driver limits the registers to 0-F, so I assume there 732 * are actually 16 present on the device. 733 * 734 * On an UART interrupt, 4 bytes of data come in on the interrupt 735 * endpoint. The bytes are 0xe8 IIR LSR MSR. 736 * 737 * The baudrate seems to be generated from the 12MHz crystal, using 738 * 4-times subsampling. So quot=12e6/(4*baud). Also see description 739 * of register E. 740 * 741 * Registers 0-7: 742 * These seem to be the same as for a regular 16450. The FCR is set 743 * to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between 744 * the UART and the USB bridge/DMA engine. 745 * 746 * Register 8: 747 * By trial and error, I found out that bit 0 enables hardware CTS, 748 * stopping TX when CTS is +5V. Bit 1 does the same for RTS, making 749 * RTS +5V when the 3116 cannot transfer the data to the USB bus 750 * (verified by disabling the reading URB). Note that as far as I can 751 * tell, the windows driver does NOT use this, so there might be some 752 * hardware bug or something. 753 * 754 * According to a patch provided here 755 * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used 756 * as an IrDA dongle. Since I do not have such a thing, I could not 757 * investigate that aspect. However, I can speculate ;-). 758 * 759 * - IrDA encodes data differently than RS232. Most likely, one of 760 * the bits in registers 9..E enables the IR ENDEC (encoder/decoder). 761 * - Depending on the IR transceiver, the input and output need to be 762 * inverted, so there are probably bits for that as well. 763 * - IrDA is half-duplex, so there should be a bit for selecting that. 764 * 765 * This still leaves at least two registers unaccounted for. Perhaps 766 * The chip can do XON/XOFF or CRC in HW? 767 * 768 * Register 9: 769 * Set to 0x00 for IrDA, when the baudrate is initialised. 770 * 771 * Register A: 772 * Set to 0x01 for IrDA, at init. 773 * 774 * Register B: 775 * Set to 0x01 for IrDA, 0x00 for RS232, at init. 776 * 777 * Register C: 778 * Set to 00 for IrDA, at init. 779 * 780 * Register D: 781 * Set to 0x41 for IrDA, at init. 782 * 783 * Register E: 784 * Somekind of baudrate override. The windows driver seems to set 785 * this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600. 786 * Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer, 787 * it could be somekind of subdivisor thingy. 788 * However,it does not seem to do anything: selecting 921600 (divisor 3, 789 * reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would 790 * work, but they don't. 791 * 792 * Register F: unknown 793 */ 794