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 return result; 87 } 88 89 static int ark3116_read_reg(struct usb_serial *serial, 90 unsigned reg, unsigned char *buf) 91 { 92 int result; 93 /* 0xfe 0xc0 are magic values taken from original driver */ 94 result = usb_control_msg(serial->dev, 95 usb_rcvctrlpipe(serial->dev, 0), 96 0xfe, 0xc0, 0, reg, 97 buf, 1, ARK_TIMEOUT); 98 if (result < 1) { 99 dev_err(&serial->interface->dev, 100 "failed to read register %u: %d\n", 101 reg, result); 102 if (result >= 0) 103 result = -EIO; 104 105 return result; 106 } 107 108 return buf[0]; 109 } 110 111 static inline int calc_divisor(int bps) 112 { 113 /* Original ark3116 made some exceptions in rounding here 114 * because windows did the same. Assume that is not really 115 * necessary. 116 * Crystal is 12MHz, probably because of USB, but we divide by 4? 117 */ 118 return (12000000 + 2*bps) / (4*bps); 119 } 120 121 static int ark3116_port_probe(struct usb_serial_port *port) 122 { 123 struct usb_serial *serial = port->serial; 124 struct ark3116_private *priv; 125 126 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 127 if (!priv) 128 return -ENOMEM; 129 130 mutex_init(&priv->hw_lock); 131 spin_lock_init(&priv->status_lock); 132 133 priv->irda = is_irda(serial); 134 135 usb_set_serial_port_data(port, priv); 136 137 /* setup the hardware */ 138 ark3116_write_reg(serial, UART_IER, 0); 139 /* disable DMA */ 140 ark3116_write_reg(serial, UART_FCR, 0); 141 /* handshake control */ 142 priv->hcr = 0; 143 ark3116_write_reg(serial, 0x8 , 0); 144 /* modem control */ 145 priv->mcr = 0; 146 ark3116_write_reg(serial, UART_MCR, 0); 147 148 if (!(priv->irda)) { 149 ark3116_write_reg(serial, 0xb , 0); 150 } else { 151 ark3116_write_reg(serial, 0xb , 1); 152 ark3116_write_reg(serial, 0xc , 0); 153 ark3116_write_reg(serial, 0xd , 0x41); 154 ark3116_write_reg(serial, 0xa , 1); 155 } 156 157 /* setup baudrate */ 158 ark3116_write_reg(serial, UART_LCR, UART_LCR_DLAB); 159 160 /* setup for 9600 8N1 */ 161 priv->quot = calc_divisor(9600); 162 ark3116_write_reg(serial, UART_DLL, priv->quot & 0xff); 163 ark3116_write_reg(serial, UART_DLM, (priv->quot>>8) & 0xff); 164 165 priv->lcr = UART_LCR_WLEN8; 166 ark3116_write_reg(serial, UART_LCR, UART_LCR_WLEN8); 167 168 ark3116_write_reg(serial, 0xe, 0); 169 170 if (priv->irda) 171 ark3116_write_reg(serial, 0x9, 0); 172 173 dev_info(&port->dev, "using %s mode\n", priv->irda ? "IrDA" : "RS232"); 174 175 return 0; 176 } 177 178 static int ark3116_port_remove(struct usb_serial_port *port) 179 { 180 struct ark3116_private *priv = usb_get_serial_port_data(port); 181 182 /* device is closed, so URBs and DMA should be down */ 183 mutex_destroy(&priv->hw_lock); 184 kfree(priv); 185 186 return 0; 187 } 188 189 static void ark3116_init_termios(struct tty_struct *tty) 190 { 191 struct ktermios *termios = &tty->termios; 192 *termios = tty_std_termios; 193 termios->c_cflag = B9600 | CS8 194 | CREAD | HUPCL | CLOCAL; 195 termios->c_ispeed = 9600; 196 termios->c_ospeed = 9600; 197 } 198 199 static void ark3116_set_termios(struct tty_struct *tty, 200 struct usb_serial_port *port, 201 struct ktermios *old_termios) 202 { 203 struct usb_serial *serial = port->serial; 204 struct ark3116_private *priv = usb_get_serial_port_data(port); 205 struct ktermios *termios = &tty->termios; 206 unsigned int cflag = termios->c_cflag; 207 int bps = tty_get_baud_rate(tty); 208 int quot; 209 __u8 lcr, hcr, eval; 210 211 /* set data bit count */ 212 switch (cflag & CSIZE) { 213 case CS5: 214 lcr = UART_LCR_WLEN5; 215 break; 216 case CS6: 217 lcr = UART_LCR_WLEN6; 218 break; 219 case CS7: 220 lcr = UART_LCR_WLEN7; 221 break; 222 default: 223 case CS8: 224 lcr = UART_LCR_WLEN8; 225 break; 226 } 227 if (cflag & CSTOPB) 228 lcr |= UART_LCR_STOP; 229 if (cflag & PARENB) 230 lcr |= UART_LCR_PARITY; 231 if (!(cflag & PARODD)) 232 lcr |= UART_LCR_EPAR; 233 #ifdef CMSPAR 234 if (cflag & CMSPAR) 235 lcr |= UART_LCR_SPAR; 236 #endif 237 /* handshake control */ 238 hcr = (cflag & CRTSCTS) ? 0x03 : 0x00; 239 240 /* calc baudrate */ 241 dev_dbg(&port->dev, "%s - setting bps to %d\n", __func__, bps); 242 eval = 0; 243 switch (bps) { 244 case 0: 245 quot = calc_divisor(9600); 246 break; 247 default: 248 if ((bps < 75) || (bps > 3000000)) 249 bps = 9600; 250 quot = calc_divisor(bps); 251 break; 252 case 460800: 253 eval = 1; 254 quot = calc_divisor(bps); 255 break; 256 case 921600: 257 eval = 2; 258 quot = calc_divisor(bps); 259 break; 260 } 261 262 /* Update state: synchronize */ 263 mutex_lock(&priv->hw_lock); 264 265 /* keep old LCR_SBC bit */ 266 lcr |= (priv->lcr & UART_LCR_SBC); 267 268 dev_dbg(&port->dev, "%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d\n", 269 __func__, hcr, lcr, quot); 270 271 /* handshake control */ 272 if (priv->hcr != hcr) { 273 priv->hcr = hcr; 274 ark3116_write_reg(serial, 0x8, hcr); 275 } 276 277 /* baudrate */ 278 if (priv->quot != quot) { 279 priv->quot = quot; 280 priv->lcr = lcr; /* need to write lcr anyway */ 281 282 /* disable DMA since transmit/receive is 283 * shadowed by UART_DLL 284 */ 285 ark3116_write_reg(serial, UART_FCR, 0); 286 287 ark3116_write_reg(serial, UART_LCR, 288 lcr|UART_LCR_DLAB); 289 ark3116_write_reg(serial, UART_DLL, quot & 0xff); 290 ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff); 291 292 /* restore lcr */ 293 ark3116_write_reg(serial, UART_LCR, lcr); 294 /* magic baudrate thingy: not sure what it does, 295 * but windows does this as well. 296 */ 297 ark3116_write_reg(serial, 0xe, eval); 298 299 /* enable DMA */ 300 ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT); 301 } else if (priv->lcr != lcr) { 302 priv->lcr = lcr; 303 ark3116_write_reg(serial, UART_LCR, lcr); 304 } 305 306 mutex_unlock(&priv->hw_lock); 307 308 /* check for software flow control */ 309 if (I_IXOFF(tty) || I_IXON(tty)) { 310 dev_warn(&port->dev, 311 "software flow control not implemented\n"); 312 } 313 314 /* Don't rewrite B0 */ 315 if (tty_termios_baud_rate(termios)) 316 tty_termios_encode_baud_rate(termios, bps, bps); 317 } 318 319 static void ark3116_close(struct usb_serial_port *port) 320 { 321 struct usb_serial *serial = port->serial; 322 323 /* disable DMA */ 324 ark3116_write_reg(serial, UART_FCR, 0); 325 326 /* deactivate interrupts */ 327 ark3116_write_reg(serial, UART_IER, 0); 328 329 usb_serial_generic_close(port); 330 331 usb_kill_urb(port->interrupt_in_urb); 332 } 333 334 static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port) 335 { 336 struct ark3116_private *priv = usb_get_serial_port_data(port); 337 struct usb_serial *serial = port->serial; 338 unsigned char *buf; 339 int result; 340 341 buf = kmalloc(1, GFP_KERNEL); 342 if (buf == NULL) 343 return -ENOMEM; 344 345 result = usb_serial_generic_open(tty, port); 346 if (result) { 347 dev_dbg(&port->dev, 348 "%s - usb_serial_generic_open failed: %d\n", 349 __func__, result); 350 goto err_free; 351 } 352 353 /* remove any data still left: also clears error state */ 354 ark3116_read_reg(serial, UART_RX, buf); 355 356 /* read modem status */ 357 result = ark3116_read_reg(serial, UART_MSR, buf); 358 if (result < 0) 359 goto err_close; 360 priv->msr = *buf; 361 362 /* read line status */ 363 result = ark3116_read_reg(serial, UART_LSR, buf); 364 if (result < 0) 365 goto err_close; 366 priv->lsr = *buf; 367 368 result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL); 369 if (result) { 370 dev_err(&port->dev, "submit irq_in urb failed %d\n", 371 result); 372 goto err_close; 373 } 374 375 /* activate interrupts */ 376 ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI); 377 378 /* enable DMA */ 379 ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT); 380 381 /* setup termios */ 382 if (tty) 383 ark3116_set_termios(tty, port, NULL); 384 385 kfree(buf); 386 387 return 0; 388 389 err_close: 390 usb_serial_generic_close(port); 391 err_free: 392 kfree(buf); 393 394 return result; 395 } 396 397 static int ark3116_ioctl(struct tty_struct *tty, 398 unsigned int cmd, unsigned long arg) 399 { 400 struct usb_serial_port *port = tty->driver_data; 401 struct serial_struct serstruct; 402 void __user *user_arg = (void __user *)arg; 403 404 switch (cmd) { 405 case TIOCGSERIAL: 406 /* XXX: Some of these values are probably wrong. */ 407 memset(&serstruct, 0, sizeof(serstruct)); 408 serstruct.type = PORT_16654; 409 serstruct.line = port->minor; 410 serstruct.port = port->port_number; 411 serstruct.custom_divisor = 0; 412 serstruct.baud_base = 460800; 413 414 if (copy_to_user(user_arg, &serstruct, sizeof(serstruct))) 415 return -EFAULT; 416 417 return 0; 418 case TIOCSSERIAL: 419 if (copy_from_user(&serstruct, user_arg, sizeof(serstruct))) 420 return -EFAULT; 421 return 0; 422 } 423 424 return -ENOIOCTLCMD; 425 } 426 427 static int ark3116_tiocmget(struct tty_struct *tty) 428 { 429 struct usb_serial_port *port = tty->driver_data; 430 struct ark3116_private *priv = usb_get_serial_port_data(port); 431 __u32 status; 432 __u32 ctrl; 433 unsigned long flags; 434 435 mutex_lock(&priv->hw_lock); 436 ctrl = priv->mcr; 437 mutex_unlock(&priv->hw_lock); 438 439 spin_lock_irqsave(&priv->status_lock, flags); 440 status = priv->msr; 441 spin_unlock_irqrestore(&priv->status_lock, flags); 442 443 return (status & UART_MSR_DSR ? TIOCM_DSR : 0) | 444 (status & UART_MSR_CTS ? TIOCM_CTS : 0) | 445 (status & UART_MSR_RI ? TIOCM_RI : 0) | 446 (status & UART_MSR_DCD ? TIOCM_CD : 0) | 447 (ctrl & UART_MCR_DTR ? TIOCM_DTR : 0) | 448 (ctrl & UART_MCR_RTS ? TIOCM_RTS : 0) | 449 (ctrl & UART_MCR_OUT1 ? TIOCM_OUT1 : 0) | 450 (ctrl & UART_MCR_OUT2 ? TIOCM_OUT2 : 0); 451 } 452 453 static int ark3116_tiocmset(struct tty_struct *tty, 454 unsigned set, unsigned clr) 455 { 456 struct usb_serial_port *port = tty->driver_data; 457 struct ark3116_private *priv = usb_get_serial_port_data(port); 458 459 /* we need to take the mutex here, to make sure that the value 460 * in priv->mcr is actually the one that is in the hardware 461 */ 462 463 mutex_lock(&priv->hw_lock); 464 465 if (set & TIOCM_RTS) 466 priv->mcr |= UART_MCR_RTS; 467 if (set & TIOCM_DTR) 468 priv->mcr |= UART_MCR_DTR; 469 if (set & TIOCM_OUT1) 470 priv->mcr |= UART_MCR_OUT1; 471 if (set & TIOCM_OUT2) 472 priv->mcr |= UART_MCR_OUT2; 473 if (clr & TIOCM_RTS) 474 priv->mcr &= ~UART_MCR_RTS; 475 if (clr & TIOCM_DTR) 476 priv->mcr &= ~UART_MCR_DTR; 477 if (clr & TIOCM_OUT1) 478 priv->mcr &= ~UART_MCR_OUT1; 479 if (clr & TIOCM_OUT2) 480 priv->mcr &= ~UART_MCR_OUT2; 481 482 ark3116_write_reg(port->serial, UART_MCR, priv->mcr); 483 484 mutex_unlock(&priv->hw_lock); 485 486 return 0; 487 } 488 489 static void ark3116_break_ctl(struct tty_struct *tty, int break_state) 490 { 491 struct usb_serial_port *port = tty->driver_data; 492 struct ark3116_private *priv = usb_get_serial_port_data(port); 493 494 /* LCR is also used for other things: protect access */ 495 mutex_lock(&priv->hw_lock); 496 497 if (break_state) 498 priv->lcr |= UART_LCR_SBC; 499 else 500 priv->lcr &= ~UART_LCR_SBC; 501 502 ark3116_write_reg(port->serial, UART_LCR, priv->lcr); 503 504 mutex_unlock(&priv->hw_lock); 505 } 506 507 static void ark3116_update_msr(struct usb_serial_port *port, __u8 msr) 508 { 509 struct ark3116_private *priv = usb_get_serial_port_data(port); 510 unsigned long flags; 511 512 spin_lock_irqsave(&priv->status_lock, flags); 513 priv->msr = msr; 514 spin_unlock_irqrestore(&priv->status_lock, flags); 515 516 if (msr & UART_MSR_ANY_DELTA) { 517 /* update input line counters */ 518 if (msr & UART_MSR_DCTS) 519 port->icount.cts++; 520 if (msr & UART_MSR_DDSR) 521 port->icount.dsr++; 522 if (msr & UART_MSR_DDCD) 523 port->icount.dcd++; 524 if (msr & UART_MSR_TERI) 525 port->icount.rng++; 526 wake_up_interruptible(&port->port.delta_msr_wait); 527 } 528 } 529 530 static void ark3116_update_lsr(struct usb_serial_port *port, __u8 lsr) 531 { 532 struct ark3116_private *priv = usb_get_serial_port_data(port); 533 unsigned long flags; 534 535 spin_lock_irqsave(&priv->status_lock, flags); 536 /* combine bits */ 537 priv->lsr |= lsr; 538 spin_unlock_irqrestore(&priv->status_lock, flags); 539 540 if (lsr&UART_LSR_BRK_ERROR_BITS) { 541 if (lsr & UART_LSR_BI) 542 port->icount.brk++; 543 if (lsr & UART_LSR_FE) 544 port->icount.frame++; 545 if (lsr & UART_LSR_PE) 546 port->icount.parity++; 547 if (lsr & UART_LSR_OE) 548 port->icount.overrun++; 549 } 550 } 551 552 static void ark3116_read_int_callback(struct urb *urb) 553 { 554 struct usb_serial_port *port = urb->context; 555 int status = urb->status; 556 const __u8 *data = urb->transfer_buffer; 557 int result; 558 559 switch (status) { 560 case -ECONNRESET: 561 case -ENOENT: 562 case -ESHUTDOWN: 563 /* this urb is terminated, clean up */ 564 dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n", 565 __func__, status); 566 return; 567 default: 568 dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n", 569 __func__, status); 570 break; 571 case 0: /* success */ 572 /* discovered this by trail and error... */ 573 if ((urb->actual_length == 4) && (data[0] == 0xe8)) { 574 const __u8 id = data[1]&UART_IIR_ID; 575 dev_dbg(&port->dev, "%s: iir=%02x\n", __func__, data[1]); 576 if (id == UART_IIR_MSI) { 577 dev_dbg(&port->dev, "%s: msr=%02x\n", 578 __func__, data[3]); 579 ark3116_update_msr(port, data[3]); 580 break; 581 } else if (id == UART_IIR_RLSI) { 582 dev_dbg(&port->dev, "%s: lsr=%02x\n", 583 __func__, data[2]); 584 ark3116_update_lsr(port, data[2]); 585 break; 586 } 587 } 588 /* 589 * Not sure what this data meant... 590 */ 591 usb_serial_debug_data(&port->dev, __func__, 592 urb->actual_length, 593 urb->transfer_buffer); 594 break; 595 } 596 597 result = usb_submit_urb(urb, GFP_ATOMIC); 598 if (result) 599 dev_err(&port->dev, "failed to resubmit interrupt urb: %d\n", 600 result); 601 } 602 603 604 /* Data comes in via the bulk (data) URB, errors/interrupts via the int URB. 605 * This means that we cannot be sure which data byte has an associated error 606 * condition, so we report an error for all data in the next bulk read. 607 * 608 * Actually, there might even be a window between the bulk data leaving the 609 * ark and reading/resetting the lsr in the read_bulk_callback where an 610 * interrupt for the next data block could come in. 611 * Without somekind of ordering on the ark, we would have to report the 612 * error for the next block of data as well... 613 * For now, let's pretend this can't happen. 614 */ 615 static void ark3116_process_read_urb(struct urb *urb) 616 { 617 struct usb_serial_port *port = urb->context; 618 struct ark3116_private *priv = usb_get_serial_port_data(port); 619 unsigned char *data = urb->transfer_buffer; 620 char tty_flag = TTY_NORMAL; 621 unsigned long flags; 622 __u32 lsr; 623 624 /* update line status */ 625 spin_lock_irqsave(&priv->status_lock, flags); 626 lsr = priv->lsr; 627 priv->lsr &= ~UART_LSR_BRK_ERROR_BITS; 628 spin_unlock_irqrestore(&priv->status_lock, flags); 629 630 if (!urb->actual_length) 631 return; 632 633 if (lsr & UART_LSR_BRK_ERROR_BITS) { 634 if (lsr & UART_LSR_BI) 635 tty_flag = TTY_BREAK; 636 else if (lsr & UART_LSR_PE) 637 tty_flag = TTY_PARITY; 638 else if (lsr & UART_LSR_FE) 639 tty_flag = TTY_FRAME; 640 641 /* overrun is special, not associated with a char */ 642 if (lsr & UART_LSR_OE) 643 tty_insert_flip_char(&port->port, 0, TTY_OVERRUN); 644 } 645 tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag, 646 urb->actual_length); 647 tty_flip_buffer_push(&port->port); 648 } 649 650 static struct usb_serial_driver ark3116_device = { 651 .driver = { 652 .owner = THIS_MODULE, 653 .name = "ark3116", 654 }, 655 .id_table = id_table, 656 .num_ports = 1, 657 .num_bulk_in = 1, 658 .num_bulk_out = 1, 659 .num_interrupt_in = 1, 660 .port_probe = ark3116_port_probe, 661 .port_remove = ark3116_port_remove, 662 .set_termios = ark3116_set_termios, 663 .init_termios = ark3116_init_termios, 664 .ioctl = ark3116_ioctl, 665 .tiocmget = ark3116_tiocmget, 666 .tiocmset = ark3116_tiocmset, 667 .tiocmiwait = usb_serial_generic_tiocmiwait, 668 .get_icount = usb_serial_generic_get_icount, 669 .open = ark3116_open, 670 .close = ark3116_close, 671 .break_ctl = ark3116_break_ctl, 672 .read_int_callback = ark3116_read_int_callback, 673 .process_read_urb = ark3116_process_read_urb, 674 }; 675 676 static struct usb_serial_driver * const serial_drivers[] = { 677 &ark3116_device, NULL 678 }; 679 680 module_usb_serial_driver(serial_drivers, id_table); 681 682 MODULE_LICENSE("GPL"); 683 684 MODULE_AUTHOR(DRIVER_AUTHOR); 685 MODULE_DESCRIPTION(DRIVER_DESC); 686 687 /* 688 * The following describes what I learned from studying the old 689 * ark3116.c driver, disassembling the windows driver, and some lucky 690 * guesses. Since I do not have any datasheet or other 691 * documentation, inaccuracies are almost guaranteed. 692 * 693 * Some specs for the ARK3116 can be found here: 694 * http://web.archive.org/web/20060318000438/ 695 * www.arkmicro.com/en/products/view.php?id=10 696 * On that page, 2 GPIO pins are mentioned: I assume these are the 697 * OUT1 and OUT2 pins of the UART, so I added support for those 698 * through the MCR. Since the pins are not available on my hardware, 699 * I could not verify this. 700 * Also, it states there is "on-chip hardware flow control". I have 701 * discovered how to enable that. Unfortunately, I do not know how to 702 * enable XON/XOFF (software) flow control, which would need support 703 * from the chip as well to work. Because of the wording on the web 704 * page there is a real possibility the chip simply does not support 705 * software flow control. 706 * 707 * I got my ark3116 as part of a mobile phone adapter cable. On the 708 * PCB, the following numbered contacts are present: 709 * 710 * 1:- +5V 711 * 2:o DTR 712 * 3:i RX 713 * 4:i DCD 714 * 5:o RTS 715 * 6:o TX 716 * 7:i RI 717 * 8:i DSR 718 * 10:- 0V 719 * 11:i CTS 720 * 721 * On my chip, all signals seem to be 3.3V, but 5V tolerant. But that 722 * may be different for the one you have ;-). 723 * 724 * The windows driver limits the registers to 0-F, so I assume there 725 * are actually 16 present on the device. 726 * 727 * On an UART interrupt, 4 bytes of data come in on the interrupt 728 * endpoint. The bytes are 0xe8 IIR LSR MSR. 729 * 730 * The baudrate seems to be generated from the 12MHz crystal, using 731 * 4-times subsampling. So quot=12e6/(4*baud). Also see description 732 * of register E. 733 * 734 * Registers 0-7: 735 * These seem to be the same as for a regular 16450. The FCR is set 736 * to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between 737 * the UART and the USB bridge/DMA engine. 738 * 739 * Register 8: 740 * By trial and error, I found out that bit 0 enables hardware CTS, 741 * stopping TX when CTS is +5V. Bit 1 does the same for RTS, making 742 * RTS +5V when the 3116 cannot transfer the data to the USB bus 743 * (verified by disabling the reading URB). Note that as far as I can 744 * tell, the windows driver does NOT use this, so there might be some 745 * hardware bug or something. 746 * 747 * According to a patch provided here 748 * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used 749 * as an IrDA dongle. Since I do not have such a thing, I could not 750 * investigate that aspect. However, I can speculate ;-). 751 * 752 * - IrDA encodes data differently than RS232. Most likely, one of 753 * the bits in registers 9..E enables the IR ENDEC (encoder/decoder). 754 * - Depending on the IR transceiver, the input and output need to be 755 * inverted, so there are probably bits for that as well. 756 * - IrDA is half-duplex, so there should be a bit for selecting that. 757 * 758 * This still leaves at least two registers unaccounted for. Perhaps 759 * The chip can do XON/XOFF or CRC in HW? 760 * 761 * Register 9: 762 * Set to 0x00 for IrDA, when the baudrate is initialised. 763 * 764 * Register A: 765 * Set to 0x01 for IrDA, at init. 766 * 767 * Register B: 768 * Set to 0x01 for IrDA, 0x00 for RS232, at init. 769 * 770 * Register C: 771 * Set to 00 for IrDA, at init. 772 * 773 * Register D: 774 * Set to 0x41 for IrDA, at init. 775 * 776 * Register E: 777 * Somekind of baudrate override. The windows driver seems to set 778 * this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600. 779 * Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer, 780 * it could be somekind of subdivisor thingy. 781 * However,it does not seem to do anything: selecting 921600 (divisor 3, 782 * reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would 783 * work, but they don't. 784 * 785 * Register F: unknown 786 */ 787