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) 6 * 7 * ark3116 8 * - implements a driver for the arkmicro ark3116 chipset (vendor=0x6547, 9 * productid=0x0232) (used in a datacable called KQ-U8A) 10 * 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. 13 * 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. 18 * 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. 23 */ 24 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> 38 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" 43 44 /* usb timeout of 1 second */ 45 #define ARK_TIMEOUT 1000 46 47 static const struct usb_device_id id_table[] = { 48 { USB_DEVICE(0x6547, 0x0232) }, 49 { USB_DEVICE(0x18ec, 0x3118) }, /* USB to IrDA adapter */ 50 { }, 51 }; 52 MODULE_DEVICE_TABLE(usb, id_table); 53 54 static int is_irda(struct usb_serial *serial) 55 { 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; 61 } 62 63 struct ark3116_private { 64 int irda; /* 1 for irda device */ 65 66 /* protects hw register updates */ 67 struct mutex hw_lock; 68 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 */ 74 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 */ 79 }; 80 81 static int ark3116_write_reg(struct usb_serial *serial, 82 unsigned reg, __u8 val) 83 { 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; 91 } 92 93 static int ark3116_read_reg(struct usb_serial *serial, 94 unsigned reg, unsigned char *buf) 95 { 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 < 1) { 103 dev_err(&serial->interface->dev, 104 "failed to read register %u: %d\n", 105 reg, result); 106 if (result >= 0) 107 result = -EIO; 108 109 return result; 110 } 111 112 return buf[0]; 113 } 114 115 static inline int calc_divisor(int bps) 116 { 117 /* Original ark3116 made some exceptions in rounding here 118 * because windows did the same. Assume that is not really 119 * necessary. 120 * Crystal is 12MHz, probably because of USB, but we divide by 4? 121 */ 122 return (12000000 + 2*bps) / (4*bps); 123 } 124 125 static int ark3116_port_probe(struct usb_serial_port *port) 126 { 127 struct usb_serial *serial = port->serial; 128 struct ark3116_private *priv; 129 130 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 131 if (!priv) 132 return -ENOMEM; 133 134 mutex_init(&priv->hw_lock); 135 spin_lock_init(&priv->status_lock); 136 137 priv->irda = is_irda(serial); 138 139 usb_set_serial_port_data(port, priv); 140 141 /* setup the hardware */ 142 ark3116_write_reg(serial, UART_IER, 0); 143 /* disable DMA */ 144 ark3116_write_reg(serial, UART_FCR, 0); 145 /* handshake control */ 146 priv->hcr = 0; 147 ark3116_write_reg(serial, 0x8 , 0); 148 /* modem control */ 149 priv->mcr = 0; 150 ark3116_write_reg(serial, UART_MCR, 0); 151 152 if (!(priv->irda)) { 153 ark3116_write_reg(serial, 0xb , 0); 154 } else { 155 ark3116_write_reg(serial, 0xb , 1); 156 ark3116_write_reg(serial, 0xc , 0); 157 ark3116_write_reg(serial, 0xd , 0x41); 158 ark3116_write_reg(serial, 0xa , 1); 159 } 160 161 /* setup baudrate */ 162 ark3116_write_reg(serial, UART_LCR, UART_LCR_DLAB); 163 164 /* setup for 9600 8N1 */ 165 priv->quot = calc_divisor(9600); 166 ark3116_write_reg(serial, UART_DLL, priv->quot & 0xff); 167 ark3116_write_reg(serial, UART_DLM, (priv->quot>>8) & 0xff); 168 169 priv->lcr = UART_LCR_WLEN8; 170 ark3116_write_reg(serial, UART_LCR, UART_LCR_WLEN8); 171 172 ark3116_write_reg(serial, 0xe, 0); 173 174 if (priv->irda) 175 ark3116_write_reg(serial, 0x9, 0); 176 177 dev_info(&port->dev, "using %s mode\n", priv->irda ? "IrDA" : "RS232"); 178 179 return 0; 180 } 181 182 static int ark3116_port_remove(struct usb_serial_port *port) 183 { 184 struct ark3116_private *priv = usb_get_serial_port_data(port); 185 186 /* device is closed, so URBs and DMA should be down */ 187 mutex_destroy(&priv->hw_lock); 188 kfree(priv); 189 190 return 0; 191 } 192 193 static void ark3116_init_termios(struct tty_struct *tty) 194 { 195 struct ktermios *termios = &tty->termios; 196 *termios = tty_std_termios; 197 termios->c_cflag = B9600 | CS8 198 | CREAD | HUPCL | CLOCAL; 199 termios->c_ispeed = 9600; 200 termios->c_ospeed = 9600; 201 } 202 203 static void ark3116_set_termios(struct tty_struct *tty, 204 struct usb_serial_port *port, 205 struct ktermios *old_termios) 206 { 207 struct usb_serial *serial = port->serial; 208 struct ark3116_private *priv = usb_get_serial_port_data(port); 209 struct ktermios *termios = &tty->termios; 210 unsigned int cflag = termios->c_cflag; 211 int bps = tty_get_baud_rate(tty); 212 int quot; 213 __u8 lcr, hcr, eval; 214 215 /* set data bit count */ 216 switch (cflag & CSIZE) { 217 case CS5: 218 lcr = UART_LCR_WLEN5; 219 break; 220 case CS6: 221 lcr = UART_LCR_WLEN6; 222 break; 223 case CS7: 224 lcr = UART_LCR_WLEN7; 225 break; 226 default: 227 case CS8: 228 lcr = UART_LCR_WLEN8; 229 break; 230 } 231 if (cflag & CSTOPB) 232 lcr |= UART_LCR_STOP; 233 if (cflag & PARENB) 234 lcr |= UART_LCR_PARITY; 235 if (!(cflag & PARODD)) 236 lcr |= UART_LCR_EPAR; 237 #ifdef CMSPAR 238 if (cflag & CMSPAR) 239 lcr |= UART_LCR_SPAR; 240 #endif 241 /* handshake control */ 242 hcr = (cflag & CRTSCTS) ? 0x03 : 0x00; 243 244 /* calc baudrate */ 245 dev_dbg(&port->dev, "%s - setting bps to %d\n", __func__, bps); 246 eval = 0; 247 switch (bps) { 248 case 0: 249 quot = calc_divisor(9600); 250 break; 251 default: 252 if ((bps < 75) || (bps > 3000000)) 253 bps = 9600; 254 quot = calc_divisor(bps); 255 break; 256 case 460800: 257 eval = 1; 258 quot = calc_divisor(bps); 259 break; 260 case 921600: 261 eval = 2; 262 quot = calc_divisor(bps); 263 break; 264 } 265 266 /* Update state: synchronize */ 267 mutex_lock(&priv->hw_lock); 268 269 /* keep old LCR_SBC bit */ 270 lcr |= (priv->lcr & UART_LCR_SBC); 271 272 dev_dbg(&port->dev, "%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d\n", 273 __func__, hcr, lcr, quot); 274 275 /* handshake control */ 276 if (priv->hcr != hcr) { 277 priv->hcr = hcr; 278 ark3116_write_reg(serial, 0x8, hcr); 279 } 280 281 /* baudrate */ 282 if (priv->quot != quot) { 283 priv->quot = quot; 284 priv->lcr = lcr; /* need to write lcr anyway */ 285 286 /* disable DMA since transmit/receive is 287 * shadowed by UART_DLL 288 */ 289 ark3116_write_reg(serial, UART_FCR, 0); 290 291 ark3116_write_reg(serial, UART_LCR, 292 lcr|UART_LCR_DLAB); 293 ark3116_write_reg(serial, UART_DLL, quot & 0xff); 294 ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff); 295 296 /* restore lcr */ 297 ark3116_write_reg(serial, UART_LCR, lcr); 298 /* magic baudrate thingy: not sure what it does, 299 * but windows does this as well. 300 */ 301 ark3116_write_reg(serial, 0xe, eval); 302 303 /* enable DMA */ 304 ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT); 305 } else if (priv->lcr != lcr) { 306 priv->lcr = lcr; 307 ark3116_write_reg(serial, UART_LCR, lcr); 308 } 309 310 mutex_unlock(&priv->hw_lock); 311 312 /* check for software flow control */ 313 if (I_IXOFF(tty) || I_IXON(tty)) { 314 dev_warn(&port->dev, 315 "software flow control not implemented\n"); 316 } 317 318 /* Don't rewrite B0 */ 319 if (tty_termios_baud_rate(termios)) 320 tty_termios_encode_baud_rate(termios, bps, bps); 321 } 322 323 static void ark3116_close(struct usb_serial_port *port) 324 { 325 struct usb_serial *serial = port->serial; 326 327 /* disable DMA */ 328 ark3116_write_reg(serial, UART_FCR, 0); 329 330 /* deactivate interrupts */ 331 ark3116_write_reg(serial, UART_IER, 0); 332 333 usb_serial_generic_close(port); 334 335 usb_kill_urb(port->interrupt_in_urb); 336 } 337 338 static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port) 339 { 340 struct ark3116_private *priv = usb_get_serial_port_data(port); 341 struct usb_serial *serial = port->serial; 342 unsigned char *buf; 343 int result; 344 345 buf = kmalloc(1, GFP_KERNEL); 346 if (buf == NULL) 347 return -ENOMEM; 348 349 result = usb_serial_generic_open(tty, port); 350 if (result) { 351 dev_dbg(&port->dev, 352 "%s - usb_serial_generic_open failed: %d\n", 353 __func__, result); 354 goto err_free; 355 } 356 357 /* remove any data still left: also clears error state */ 358 ark3116_read_reg(serial, UART_RX, buf); 359 360 /* read modem status */ 361 result = ark3116_read_reg(serial, UART_MSR, buf); 362 if (result < 0) 363 goto err_close; 364 priv->msr = *buf; 365 366 /* read line status */ 367 result = ark3116_read_reg(serial, UART_LSR, buf); 368 if (result < 0) 369 goto err_close; 370 priv->lsr = *buf; 371 372 result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL); 373 if (result) { 374 dev_err(&port->dev, "submit irq_in urb failed %d\n", 375 result); 376 goto err_close; 377 } 378 379 /* activate interrupts */ 380 ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI); 381 382 /* enable DMA */ 383 ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT); 384 385 /* setup termios */ 386 if (tty) 387 ark3116_set_termios(tty, port, NULL); 388 389 kfree(buf); 390 391 return 0; 392 393 err_close: 394 usb_serial_generic_close(port); 395 err_free: 396 kfree(buf); 397 398 return result; 399 } 400 401 static int ark3116_ioctl(struct tty_struct *tty, 402 unsigned int cmd, unsigned long arg) 403 { 404 struct usb_serial_port *port = tty->driver_data; 405 struct serial_struct serstruct; 406 void __user *user_arg = (void __user *)arg; 407 408 switch (cmd) { 409 case TIOCGSERIAL: 410 /* XXX: Some of these values are probably wrong. */ 411 memset(&serstruct, 0, sizeof(serstruct)); 412 serstruct.type = PORT_16654; 413 serstruct.line = port->minor; 414 serstruct.port = port->port_number; 415 serstruct.custom_divisor = 0; 416 serstruct.baud_base = 460800; 417 418 if (copy_to_user(user_arg, &serstruct, sizeof(serstruct))) 419 return -EFAULT; 420 421 return 0; 422 case TIOCSSERIAL: 423 if (copy_from_user(&serstruct, user_arg, sizeof(serstruct))) 424 return -EFAULT; 425 return 0; 426 } 427 428 return -ENOIOCTLCMD; 429 } 430 431 static int ark3116_tiocmget(struct tty_struct *tty) 432 { 433 struct usb_serial_port *port = tty->driver_data; 434 struct ark3116_private *priv = usb_get_serial_port_data(port); 435 __u32 status; 436 __u32 ctrl; 437 unsigned long flags; 438 439 mutex_lock(&priv->hw_lock); 440 ctrl = priv->mcr; 441 mutex_unlock(&priv->hw_lock); 442 443 spin_lock_irqsave(&priv->status_lock, flags); 444 status = priv->msr; 445 spin_unlock_irqrestore(&priv->status_lock, flags); 446 447 return (status & UART_MSR_DSR ? TIOCM_DSR : 0) | 448 (status & UART_MSR_CTS ? TIOCM_CTS : 0) | 449 (status & UART_MSR_RI ? TIOCM_RI : 0) | 450 (status & UART_MSR_DCD ? TIOCM_CD : 0) | 451 (ctrl & UART_MCR_DTR ? TIOCM_DTR : 0) | 452 (ctrl & UART_MCR_RTS ? TIOCM_RTS : 0) | 453 (ctrl & UART_MCR_OUT1 ? TIOCM_OUT1 : 0) | 454 (ctrl & UART_MCR_OUT2 ? TIOCM_OUT2 : 0); 455 } 456 457 static int ark3116_tiocmset(struct tty_struct *tty, 458 unsigned set, unsigned clr) 459 { 460 struct usb_serial_port *port = tty->driver_data; 461 struct ark3116_private *priv = usb_get_serial_port_data(port); 462 463 /* we need to take the mutex here, to make sure that the value 464 * in priv->mcr is actually the one that is in the hardware 465 */ 466 467 mutex_lock(&priv->hw_lock); 468 469 if (set & TIOCM_RTS) 470 priv->mcr |= UART_MCR_RTS; 471 if (set & TIOCM_DTR) 472 priv->mcr |= UART_MCR_DTR; 473 if (set & TIOCM_OUT1) 474 priv->mcr |= UART_MCR_OUT1; 475 if (set & TIOCM_OUT2) 476 priv->mcr |= UART_MCR_OUT2; 477 if (clr & TIOCM_RTS) 478 priv->mcr &= ~UART_MCR_RTS; 479 if (clr & TIOCM_DTR) 480 priv->mcr &= ~UART_MCR_DTR; 481 if (clr & TIOCM_OUT1) 482 priv->mcr &= ~UART_MCR_OUT1; 483 if (clr & TIOCM_OUT2) 484 priv->mcr &= ~UART_MCR_OUT2; 485 486 ark3116_write_reg(port->serial, UART_MCR, priv->mcr); 487 488 mutex_unlock(&priv->hw_lock); 489 490 return 0; 491 } 492 493 static void ark3116_break_ctl(struct tty_struct *tty, int break_state) 494 { 495 struct usb_serial_port *port = tty->driver_data; 496 struct ark3116_private *priv = usb_get_serial_port_data(port); 497 498 /* LCR is also used for other things: protect access */ 499 mutex_lock(&priv->hw_lock); 500 501 if (break_state) 502 priv->lcr |= UART_LCR_SBC; 503 else 504 priv->lcr &= ~UART_LCR_SBC; 505 506 ark3116_write_reg(port->serial, UART_LCR, priv->lcr); 507 508 mutex_unlock(&priv->hw_lock); 509 } 510 511 static void ark3116_update_msr(struct usb_serial_port *port, __u8 msr) 512 { 513 struct ark3116_private *priv = usb_get_serial_port_data(port); 514 unsigned long flags; 515 516 spin_lock_irqsave(&priv->status_lock, flags); 517 priv->msr = msr; 518 spin_unlock_irqrestore(&priv->status_lock, flags); 519 520 if (msr & UART_MSR_ANY_DELTA) { 521 /* update input line counters */ 522 if (msr & UART_MSR_DCTS) 523 port->icount.cts++; 524 if (msr & UART_MSR_DDSR) 525 port->icount.dsr++; 526 if (msr & UART_MSR_DDCD) 527 port->icount.dcd++; 528 if (msr & UART_MSR_TERI) 529 port->icount.rng++; 530 wake_up_interruptible(&port->port.delta_msr_wait); 531 } 532 } 533 534 static void ark3116_update_lsr(struct usb_serial_port *port, __u8 lsr) 535 { 536 struct ark3116_private *priv = usb_get_serial_port_data(port); 537 unsigned long flags; 538 539 spin_lock_irqsave(&priv->status_lock, flags); 540 /* combine bits */ 541 priv->lsr |= lsr; 542 spin_unlock_irqrestore(&priv->status_lock, flags); 543 544 if (lsr&UART_LSR_BRK_ERROR_BITS) { 545 if (lsr & UART_LSR_BI) 546 port->icount.brk++; 547 if (lsr & UART_LSR_FE) 548 port->icount.frame++; 549 if (lsr & UART_LSR_PE) 550 port->icount.parity++; 551 if (lsr & UART_LSR_OE) 552 port->icount.overrun++; 553 } 554 } 555 556 static void ark3116_read_int_callback(struct urb *urb) 557 { 558 struct usb_serial_port *port = urb->context; 559 int status = urb->status; 560 const __u8 *data = urb->transfer_buffer; 561 int result; 562 563 switch (status) { 564 case -ECONNRESET: 565 case -ENOENT: 566 case -ESHUTDOWN: 567 /* this urb is terminated, clean up */ 568 dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n", 569 __func__, status); 570 return; 571 default: 572 dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n", 573 __func__, status); 574 break; 575 case 0: /* success */ 576 /* discovered this by trail and error... */ 577 if ((urb->actual_length == 4) && (data[0] == 0xe8)) { 578 const __u8 id = data[1]&UART_IIR_ID; 579 dev_dbg(&port->dev, "%s: iir=%02x\n", __func__, data[1]); 580 if (id == UART_IIR_MSI) { 581 dev_dbg(&port->dev, "%s: msr=%02x\n", 582 __func__, data[3]); 583 ark3116_update_msr(port, data[3]); 584 break; 585 } else if (id == UART_IIR_RLSI) { 586 dev_dbg(&port->dev, "%s: lsr=%02x\n", 587 __func__, data[2]); 588 ark3116_update_lsr(port, data[2]); 589 break; 590 } 591 } 592 /* 593 * Not sure what this data meant... 594 */ 595 usb_serial_debug_data(&port->dev, __func__, 596 urb->actual_length, 597 urb->transfer_buffer); 598 break; 599 } 600 601 result = usb_submit_urb(urb, GFP_ATOMIC); 602 if (result) 603 dev_err(&port->dev, "failed to resubmit interrupt urb: %d\n", 604 result); 605 } 606 607 608 /* Data comes in via the bulk (data) URB, errors/interrupts via the int URB. 609 * This means that we cannot be sure which data byte has an associated error 610 * condition, so we report an error for all data in the next bulk read. 611 * 612 * Actually, there might even be a window between the bulk data leaving the 613 * ark and reading/resetting the lsr in the read_bulk_callback where an 614 * interrupt for the next data block could come in. 615 * Without somekind of ordering on the ark, we would have to report the 616 * error for the next block of data as well... 617 * For now, let's pretend this can't happen. 618 */ 619 static void ark3116_process_read_urb(struct urb *urb) 620 { 621 struct usb_serial_port *port = urb->context; 622 struct ark3116_private *priv = usb_get_serial_port_data(port); 623 unsigned char *data = urb->transfer_buffer; 624 char tty_flag = TTY_NORMAL; 625 unsigned long flags; 626 __u32 lsr; 627 628 /* update line status */ 629 spin_lock_irqsave(&priv->status_lock, flags); 630 lsr = priv->lsr; 631 priv->lsr &= ~UART_LSR_BRK_ERROR_BITS; 632 spin_unlock_irqrestore(&priv->status_lock, flags); 633 634 if (!urb->actual_length) 635 return; 636 637 if (lsr & UART_LSR_BRK_ERROR_BITS) { 638 if (lsr & UART_LSR_BI) 639 tty_flag = TTY_BREAK; 640 else if (lsr & UART_LSR_PE) 641 tty_flag = TTY_PARITY; 642 else if (lsr & UART_LSR_FE) 643 tty_flag = TTY_FRAME; 644 645 /* overrun is special, not associated with a char */ 646 if (lsr & UART_LSR_OE) 647 tty_insert_flip_char(&port->port, 0, TTY_OVERRUN); 648 } 649 tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag, 650 urb->actual_length); 651 tty_flip_buffer_push(&port->port); 652 } 653 654 static struct usb_serial_driver ark3116_device = { 655 .driver = { 656 .owner = THIS_MODULE, 657 .name = "ark3116", 658 }, 659 .id_table = id_table, 660 .num_ports = 1, 661 .num_bulk_in = 1, 662 .num_bulk_out = 1, 663 .num_interrupt_in = 1, 664 .port_probe = ark3116_port_probe, 665 .port_remove = ark3116_port_remove, 666 .set_termios = ark3116_set_termios, 667 .init_termios = ark3116_init_termios, 668 .ioctl = ark3116_ioctl, 669 .tiocmget = ark3116_tiocmget, 670 .tiocmset = ark3116_tiocmset, 671 .tiocmiwait = usb_serial_generic_tiocmiwait, 672 .get_icount = usb_serial_generic_get_icount, 673 .open = ark3116_open, 674 .close = ark3116_close, 675 .break_ctl = ark3116_break_ctl, 676 .read_int_callback = ark3116_read_int_callback, 677 .process_read_urb = ark3116_process_read_urb, 678 }; 679 680 static struct usb_serial_driver * const serial_drivers[] = { 681 &ark3116_device, NULL 682 }; 683 684 module_usb_serial_driver(serial_drivers, id_table); 685 686 MODULE_LICENSE("GPL"); 687 688 MODULE_AUTHOR(DRIVER_AUTHOR); 689 MODULE_DESCRIPTION(DRIVER_DESC); 690 691 /* 692 * The following describes what I learned from studying the old 693 * ark3116.c driver, disassembling the windows driver, and some lucky 694 * guesses. Since I do not have any datasheet or other 695 * documentation, inaccuracies are almost guaranteed. 696 * 697 * Some specs for the ARK3116 can be found here: 698 * http://web.archive.org/web/20060318000438/ 699 * www.arkmicro.com/en/products/view.php?id=10 700 * On that page, 2 GPIO pins are mentioned: I assume these are the 701 * OUT1 and OUT2 pins of the UART, so I added support for those 702 * through the MCR. Since the pins are not available on my hardware, 703 * I could not verify this. 704 * Also, it states there is "on-chip hardware flow control". I have 705 * discovered how to enable that. Unfortunately, I do not know how to 706 * enable XON/XOFF (software) flow control, which would need support 707 * from the chip as well to work. Because of the wording on the web 708 * page there is a real possibility the chip simply does not support 709 * software flow control. 710 * 711 * I got my ark3116 as part of a mobile phone adapter cable. On the 712 * PCB, the following numbered contacts are present: 713 * 714 * 1:- +5V 715 * 2:o DTR 716 * 3:i RX 717 * 4:i DCD 718 * 5:o RTS 719 * 6:o TX 720 * 7:i RI 721 * 8:i DSR 722 * 10:- 0V 723 * 11:i CTS 724 * 725 * On my chip, all signals seem to be 3.3V, but 5V tolerant. But that 726 * may be different for the one you have ;-). 727 * 728 * The windows driver limits the registers to 0-F, so I assume there 729 * are actually 16 present on the device. 730 * 731 * On an UART interrupt, 4 bytes of data come in on the interrupt 732 * endpoint. The bytes are 0xe8 IIR LSR MSR. 733 * 734 * The baudrate seems to be generated from the 12MHz crystal, using 735 * 4-times subsampling. So quot=12e6/(4*baud). Also see description 736 * of register E. 737 * 738 * Registers 0-7: 739 * These seem to be the same as for a regular 16450. The FCR is set 740 * to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between 741 * the UART and the USB bridge/DMA engine. 742 * 743 * Register 8: 744 * By trial and error, I found out that bit 0 enables hardware CTS, 745 * stopping TX when CTS is +5V. Bit 1 does the same for RTS, making 746 * RTS +5V when the 3116 cannot transfer the data to the USB bus 747 * (verified by disabling the reading URB). Note that as far as I can 748 * tell, the windows driver does NOT use this, so there might be some 749 * hardware bug or something. 750 * 751 * According to a patch provided here 752 * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used 753 * as an IrDA dongle. Since I do not have such a thing, I could not 754 * investigate that aspect. However, I can speculate ;-). 755 * 756 * - IrDA encodes data differently than RS232. Most likely, one of 757 * the bits in registers 9..E enables the IR ENDEC (encoder/decoder). 758 * - Depending on the IR transceiver, the input and output need to be 759 * inverted, so there are probably bits for that as well. 760 * - IrDA is half-duplex, so there should be a bit for selecting that. 761 * 762 * This still leaves at least two registers unaccounted for. Perhaps 763 * The chip can do XON/XOFF or CRC in HW? 764 * 765 * Register 9: 766 * Set to 0x00 for IrDA, when the baudrate is initialised. 767 * 768 * Register A: 769 * Set to 0x01 for IrDA, at init. 770 * 771 * Register B: 772 * Set to 0x01 for IrDA, 0x00 for RS232, at init. 773 * 774 * Register C: 775 * Set to 00 for IrDA, at init. 776 * 777 * Register D: 778 * Set to 0x41 for IrDA, at init. 779 * 780 * Register E: 781 * Somekind of baudrate override. The windows driver seems to set 782 * this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600. 783 * Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer, 784 * it could be somekind of subdivisor thingy. 785 * However,it does not seem to do anything: selecting 921600 (divisor 3, 786 * reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would 787 * work, but they don't. 788 * 789 * Register F: unknown 790 */ 791