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_attach(struct usb_serial *serial) 126 { 127 /* make sure we have our end-points */ 128 if (serial->num_bulk_in == 0 || 129 serial->num_bulk_out == 0 || 130 serial->num_interrupt_in == 0) { 131 dev_err(&serial->interface->dev, "missing endpoint\n"); 132 return -ENODEV; 133 } 134 135 return 0; 136 } 137 138 static int ark3116_port_probe(struct usb_serial_port *port) 139 { 140 struct usb_serial *serial = port->serial; 141 struct ark3116_private *priv; 142 143 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 144 if (!priv) 145 return -ENOMEM; 146 147 mutex_init(&priv->hw_lock); 148 spin_lock_init(&priv->status_lock); 149 150 priv->irda = is_irda(serial); 151 152 usb_set_serial_port_data(port, priv); 153 154 /* setup the hardware */ 155 ark3116_write_reg(serial, UART_IER, 0); 156 /* disable DMA */ 157 ark3116_write_reg(serial, UART_FCR, 0); 158 /* handshake control */ 159 priv->hcr = 0; 160 ark3116_write_reg(serial, 0x8 , 0); 161 /* modem control */ 162 priv->mcr = 0; 163 ark3116_write_reg(serial, UART_MCR, 0); 164 165 if (!(priv->irda)) { 166 ark3116_write_reg(serial, 0xb , 0); 167 } else { 168 ark3116_write_reg(serial, 0xb , 1); 169 ark3116_write_reg(serial, 0xc , 0); 170 ark3116_write_reg(serial, 0xd , 0x41); 171 ark3116_write_reg(serial, 0xa , 1); 172 } 173 174 /* setup baudrate */ 175 ark3116_write_reg(serial, UART_LCR, UART_LCR_DLAB); 176 177 /* setup for 9600 8N1 */ 178 priv->quot = calc_divisor(9600); 179 ark3116_write_reg(serial, UART_DLL, priv->quot & 0xff); 180 ark3116_write_reg(serial, UART_DLM, (priv->quot>>8) & 0xff); 181 182 priv->lcr = UART_LCR_WLEN8; 183 ark3116_write_reg(serial, UART_LCR, UART_LCR_WLEN8); 184 185 ark3116_write_reg(serial, 0xe, 0); 186 187 if (priv->irda) 188 ark3116_write_reg(serial, 0x9, 0); 189 190 dev_info(&port->dev, "using %s mode\n", priv->irda ? "IrDA" : "RS232"); 191 192 return 0; 193 } 194 195 static int ark3116_port_remove(struct usb_serial_port *port) 196 { 197 struct ark3116_private *priv = usb_get_serial_port_data(port); 198 199 /* device is closed, so URBs and DMA should be down */ 200 mutex_destroy(&priv->hw_lock); 201 kfree(priv); 202 203 return 0; 204 } 205 206 static void ark3116_init_termios(struct tty_struct *tty) 207 { 208 struct ktermios *termios = &tty->termios; 209 *termios = tty_std_termios; 210 termios->c_cflag = B9600 | CS8 211 | CREAD | HUPCL | CLOCAL; 212 termios->c_ispeed = 9600; 213 termios->c_ospeed = 9600; 214 } 215 216 static void ark3116_set_termios(struct tty_struct *tty, 217 struct usb_serial_port *port, 218 struct ktermios *old_termios) 219 { 220 struct usb_serial *serial = port->serial; 221 struct ark3116_private *priv = usb_get_serial_port_data(port); 222 struct ktermios *termios = &tty->termios; 223 unsigned int cflag = termios->c_cflag; 224 int bps = tty_get_baud_rate(tty); 225 int quot; 226 __u8 lcr, hcr, eval; 227 228 /* set data bit count */ 229 switch (cflag & CSIZE) { 230 case CS5: 231 lcr = UART_LCR_WLEN5; 232 break; 233 case CS6: 234 lcr = UART_LCR_WLEN6; 235 break; 236 case CS7: 237 lcr = UART_LCR_WLEN7; 238 break; 239 default: 240 case CS8: 241 lcr = UART_LCR_WLEN8; 242 break; 243 } 244 if (cflag & CSTOPB) 245 lcr |= UART_LCR_STOP; 246 if (cflag & PARENB) 247 lcr |= UART_LCR_PARITY; 248 if (!(cflag & PARODD)) 249 lcr |= UART_LCR_EPAR; 250 #ifdef CMSPAR 251 if (cflag & CMSPAR) 252 lcr |= UART_LCR_SPAR; 253 #endif 254 /* handshake control */ 255 hcr = (cflag & CRTSCTS) ? 0x03 : 0x00; 256 257 /* calc baudrate */ 258 dev_dbg(&port->dev, "%s - setting bps to %d\n", __func__, bps); 259 eval = 0; 260 switch (bps) { 261 case 0: 262 quot = calc_divisor(9600); 263 break; 264 default: 265 if ((bps < 75) || (bps > 3000000)) 266 bps = 9600; 267 quot = calc_divisor(bps); 268 break; 269 case 460800: 270 eval = 1; 271 quot = calc_divisor(bps); 272 break; 273 case 921600: 274 eval = 2; 275 quot = calc_divisor(bps); 276 break; 277 } 278 279 /* Update state: synchronize */ 280 mutex_lock(&priv->hw_lock); 281 282 /* keep old LCR_SBC bit */ 283 lcr |= (priv->lcr & UART_LCR_SBC); 284 285 dev_dbg(&port->dev, "%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d\n", 286 __func__, hcr, lcr, quot); 287 288 /* handshake control */ 289 if (priv->hcr != hcr) { 290 priv->hcr = hcr; 291 ark3116_write_reg(serial, 0x8, hcr); 292 } 293 294 /* baudrate */ 295 if (priv->quot != quot) { 296 priv->quot = quot; 297 priv->lcr = lcr; /* need to write lcr anyway */ 298 299 /* disable DMA since transmit/receive is 300 * shadowed by UART_DLL 301 */ 302 ark3116_write_reg(serial, UART_FCR, 0); 303 304 ark3116_write_reg(serial, UART_LCR, 305 lcr|UART_LCR_DLAB); 306 ark3116_write_reg(serial, UART_DLL, quot & 0xff); 307 ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff); 308 309 /* restore lcr */ 310 ark3116_write_reg(serial, UART_LCR, lcr); 311 /* magic baudrate thingy: not sure what it does, 312 * but windows does this as well. 313 */ 314 ark3116_write_reg(serial, 0xe, eval); 315 316 /* enable DMA */ 317 ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT); 318 } else if (priv->lcr != lcr) { 319 priv->lcr = lcr; 320 ark3116_write_reg(serial, UART_LCR, lcr); 321 } 322 323 mutex_unlock(&priv->hw_lock); 324 325 /* check for software flow control */ 326 if (I_IXOFF(tty) || I_IXON(tty)) { 327 dev_warn(&port->dev, 328 "software flow control not implemented\n"); 329 } 330 331 /* Don't rewrite B0 */ 332 if (tty_termios_baud_rate(termios)) 333 tty_termios_encode_baud_rate(termios, bps, bps); 334 } 335 336 static void ark3116_close(struct usb_serial_port *port) 337 { 338 struct usb_serial *serial = port->serial; 339 340 /* disable DMA */ 341 ark3116_write_reg(serial, UART_FCR, 0); 342 343 /* deactivate interrupts */ 344 ark3116_write_reg(serial, UART_IER, 0); 345 346 usb_serial_generic_close(port); 347 348 usb_kill_urb(port->interrupt_in_urb); 349 } 350 351 static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port) 352 { 353 struct ark3116_private *priv = usb_get_serial_port_data(port); 354 struct usb_serial *serial = port->serial; 355 unsigned char *buf; 356 int result; 357 358 buf = kmalloc(1, GFP_KERNEL); 359 if (buf == NULL) 360 return -ENOMEM; 361 362 result = usb_serial_generic_open(tty, port); 363 if (result) { 364 dev_dbg(&port->dev, 365 "%s - usb_serial_generic_open failed: %d\n", 366 __func__, result); 367 goto err_free; 368 } 369 370 /* remove any data still left: also clears error state */ 371 ark3116_read_reg(serial, UART_RX, buf); 372 373 /* read modem status */ 374 result = ark3116_read_reg(serial, UART_MSR, buf); 375 if (result < 0) 376 goto err_close; 377 priv->msr = *buf; 378 379 /* read line status */ 380 result = ark3116_read_reg(serial, UART_LSR, buf); 381 if (result < 0) 382 goto err_close; 383 priv->lsr = *buf; 384 385 result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL); 386 if (result) { 387 dev_err(&port->dev, "submit irq_in urb failed %d\n", 388 result); 389 goto err_close; 390 } 391 392 /* activate interrupts */ 393 ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI); 394 395 /* enable DMA */ 396 ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT); 397 398 /* setup termios */ 399 if (tty) 400 ark3116_set_termios(tty, port, NULL); 401 402 kfree(buf); 403 404 return 0; 405 406 err_close: 407 usb_serial_generic_close(port); 408 err_free: 409 kfree(buf); 410 411 return result; 412 } 413 414 static int ark3116_ioctl(struct tty_struct *tty, 415 unsigned int cmd, unsigned long arg) 416 { 417 struct usb_serial_port *port = tty->driver_data; 418 struct serial_struct serstruct; 419 void __user *user_arg = (void __user *)arg; 420 421 switch (cmd) { 422 case TIOCGSERIAL: 423 /* XXX: Some of these values are probably wrong. */ 424 memset(&serstruct, 0, sizeof(serstruct)); 425 serstruct.type = PORT_16654; 426 serstruct.line = port->minor; 427 serstruct.port = port->port_number; 428 serstruct.custom_divisor = 0; 429 serstruct.baud_base = 460800; 430 431 if (copy_to_user(user_arg, &serstruct, sizeof(serstruct))) 432 return -EFAULT; 433 434 return 0; 435 case TIOCSSERIAL: 436 if (copy_from_user(&serstruct, user_arg, sizeof(serstruct))) 437 return -EFAULT; 438 return 0; 439 } 440 441 return -ENOIOCTLCMD; 442 } 443 444 static int ark3116_tiocmget(struct tty_struct *tty) 445 { 446 struct usb_serial_port *port = tty->driver_data; 447 struct ark3116_private *priv = usb_get_serial_port_data(port); 448 __u32 status; 449 __u32 ctrl; 450 unsigned long flags; 451 452 mutex_lock(&priv->hw_lock); 453 ctrl = priv->mcr; 454 mutex_unlock(&priv->hw_lock); 455 456 spin_lock_irqsave(&priv->status_lock, flags); 457 status = priv->msr; 458 spin_unlock_irqrestore(&priv->status_lock, flags); 459 460 return (status & UART_MSR_DSR ? TIOCM_DSR : 0) | 461 (status & UART_MSR_CTS ? TIOCM_CTS : 0) | 462 (status & UART_MSR_RI ? TIOCM_RI : 0) | 463 (status & UART_MSR_DCD ? TIOCM_CD : 0) | 464 (ctrl & UART_MCR_DTR ? TIOCM_DTR : 0) | 465 (ctrl & UART_MCR_RTS ? TIOCM_RTS : 0) | 466 (ctrl & UART_MCR_OUT1 ? TIOCM_OUT1 : 0) | 467 (ctrl & UART_MCR_OUT2 ? TIOCM_OUT2 : 0); 468 } 469 470 static int ark3116_tiocmset(struct tty_struct *tty, 471 unsigned set, unsigned clr) 472 { 473 struct usb_serial_port *port = tty->driver_data; 474 struct ark3116_private *priv = usb_get_serial_port_data(port); 475 476 /* we need to take the mutex here, to make sure that the value 477 * in priv->mcr is actually the one that is in the hardware 478 */ 479 480 mutex_lock(&priv->hw_lock); 481 482 if (set & TIOCM_RTS) 483 priv->mcr |= UART_MCR_RTS; 484 if (set & TIOCM_DTR) 485 priv->mcr |= UART_MCR_DTR; 486 if (set & TIOCM_OUT1) 487 priv->mcr |= UART_MCR_OUT1; 488 if (set & TIOCM_OUT2) 489 priv->mcr |= UART_MCR_OUT2; 490 if (clr & TIOCM_RTS) 491 priv->mcr &= ~UART_MCR_RTS; 492 if (clr & TIOCM_DTR) 493 priv->mcr &= ~UART_MCR_DTR; 494 if (clr & TIOCM_OUT1) 495 priv->mcr &= ~UART_MCR_OUT1; 496 if (clr & TIOCM_OUT2) 497 priv->mcr &= ~UART_MCR_OUT2; 498 499 ark3116_write_reg(port->serial, UART_MCR, priv->mcr); 500 501 mutex_unlock(&priv->hw_lock); 502 503 return 0; 504 } 505 506 static void ark3116_break_ctl(struct tty_struct *tty, int break_state) 507 { 508 struct usb_serial_port *port = tty->driver_data; 509 struct ark3116_private *priv = usb_get_serial_port_data(port); 510 511 /* LCR is also used for other things: protect access */ 512 mutex_lock(&priv->hw_lock); 513 514 if (break_state) 515 priv->lcr |= UART_LCR_SBC; 516 else 517 priv->lcr &= ~UART_LCR_SBC; 518 519 ark3116_write_reg(port->serial, UART_LCR, priv->lcr); 520 521 mutex_unlock(&priv->hw_lock); 522 } 523 524 static void ark3116_update_msr(struct usb_serial_port *port, __u8 msr) 525 { 526 struct ark3116_private *priv = usb_get_serial_port_data(port); 527 unsigned long flags; 528 529 spin_lock_irqsave(&priv->status_lock, flags); 530 priv->msr = msr; 531 spin_unlock_irqrestore(&priv->status_lock, flags); 532 533 if (msr & UART_MSR_ANY_DELTA) { 534 /* update input line counters */ 535 if (msr & UART_MSR_DCTS) 536 port->icount.cts++; 537 if (msr & UART_MSR_DDSR) 538 port->icount.dsr++; 539 if (msr & UART_MSR_DDCD) 540 port->icount.dcd++; 541 if (msr & UART_MSR_TERI) 542 port->icount.rng++; 543 wake_up_interruptible(&port->port.delta_msr_wait); 544 } 545 } 546 547 static void ark3116_update_lsr(struct usb_serial_port *port, __u8 lsr) 548 { 549 struct ark3116_private *priv = usb_get_serial_port_data(port); 550 unsigned long flags; 551 552 spin_lock_irqsave(&priv->status_lock, flags); 553 /* combine bits */ 554 priv->lsr |= lsr; 555 spin_unlock_irqrestore(&priv->status_lock, flags); 556 557 if (lsr&UART_LSR_BRK_ERROR_BITS) { 558 if (lsr & UART_LSR_BI) 559 port->icount.brk++; 560 if (lsr & UART_LSR_FE) 561 port->icount.frame++; 562 if (lsr & UART_LSR_PE) 563 port->icount.parity++; 564 if (lsr & UART_LSR_OE) 565 port->icount.overrun++; 566 } 567 } 568 569 static void ark3116_read_int_callback(struct urb *urb) 570 { 571 struct usb_serial_port *port = urb->context; 572 int status = urb->status; 573 const __u8 *data = urb->transfer_buffer; 574 int result; 575 576 switch (status) { 577 case -ECONNRESET: 578 case -ENOENT: 579 case -ESHUTDOWN: 580 /* this urb is terminated, clean up */ 581 dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n", 582 __func__, status); 583 return; 584 default: 585 dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n", 586 __func__, status); 587 break; 588 case 0: /* success */ 589 /* discovered this by trail and error... */ 590 if ((urb->actual_length == 4) && (data[0] == 0xe8)) { 591 const __u8 id = data[1]&UART_IIR_ID; 592 dev_dbg(&port->dev, "%s: iir=%02x\n", __func__, data[1]); 593 if (id == UART_IIR_MSI) { 594 dev_dbg(&port->dev, "%s: msr=%02x\n", 595 __func__, data[3]); 596 ark3116_update_msr(port, data[3]); 597 break; 598 } else if (id == UART_IIR_RLSI) { 599 dev_dbg(&port->dev, "%s: lsr=%02x\n", 600 __func__, data[2]); 601 ark3116_update_lsr(port, data[2]); 602 break; 603 } 604 } 605 /* 606 * Not sure what this data meant... 607 */ 608 usb_serial_debug_data(&port->dev, __func__, 609 urb->actual_length, 610 urb->transfer_buffer); 611 break; 612 } 613 614 result = usb_submit_urb(urb, GFP_ATOMIC); 615 if (result) 616 dev_err(&port->dev, "failed to resubmit interrupt urb: %d\n", 617 result); 618 } 619 620 621 /* Data comes in via the bulk (data) URB, errors/interrupts via the int URB. 622 * This means that we cannot be sure which data byte has an associated error 623 * condition, so we report an error for all data in the next bulk read. 624 * 625 * Actually, there might even be a window between the bulk data leaving the 626 * ark and reading/resetting the lsr in the read_bulk_callback where an 627 * interrupt for the next data block could come in. 628 * Without somekind of ordering on the ark, we would have to report the 629 * error for the next block of data as well... 630 * For now, let's pretend this can't happen. 631 */ 632 static void ark3116_process_read_urb(struct urb *urb) 633 { 634 struct usb_serial_port *port = urb->context; 635 struct ark3116_private *priv = usb_get_serial_port_data(port); 636 unsigned char *data = urb->transfer_buffer; 637 char tty_flag = TTY_NORMAL; 638 unsigned long flags; 639 __u32 lsr; 640 641 /* update line status */ 642 spin_lock_irqsave(&priv->status_lock, flags); 643 lsr = priv->lsr; 644 priv->lsr &= ~UART_LSR_BRK_ERROR_BITS; 645 spin_unlock_irqrestore(&priv->status_lock, flags); 646 647 if (!urb->actual_length) 648 return; 649 650 if (lsr & UART_LSR_BRK_ERROR_BITS) { 651 if (lsr & UART_LSR_BI) 652 tty_flag = TTY_BREAK; 653 else if (lsr & UART_LSR_PE) 654 tty_flag = TTY_PARITY; 655 else if (lsr & UART_LSR_FE) 656 tty_flag = TTY_FRAME; 657 658 /* overrun is special, not associated with a char */ 659 if (lsr & UART_LSR_OE) 660 tty_insert_flip_char(&port->port, 0, TTY_OVERRUN); 661 } 662 tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag, 663 urb->actual_length); 664 tty_flip_buffer_push(&port->port); 665 } 666 667 static struct usb_serial_driver ark3116_device = { 668 .driver = { 669 .owner = THIS_MODULE, 670 .name = "ark3116", 671 }, 672 .id_table = id_table, 673 .num_ports = 1, 674 .attach = ark3116_attach, 675 .port_probe = ark3116_port_probe, 676 .port_remove = ark3116_port_remove, 677 .set_termios = ark3116_set_termios, 678 .init_termios = ark3116_init_termios, 679 .ioctl = ark3116_ioctl, 680 .tiocmget = ark3116_tiocmget, 681 .tiocmset = ark3116_tiocmset, 682 .tiocmiwait = usb_serial_generic_tiocmiwait, 683 .get_icount = usb_serial_generic_get_icount, 684 .open = ark3116_open, 685 .close = ark3116_close, 686 .break_ctl = ark3116_break_ctl, 687 .read_int_callback = ark3116_read_int_callback, 688 .process_read_urb = ark3116_process_read_urb, 689 }; 690 691 static struct usb_serial_driver * const serial_drivers[] = { 692 &ark3116_device, NULL 693 }; 694 695 module_usb_serial_driver(serial_drivers, id_table); 696 697 MODULE_LICENSE("GPL"); 698 699 MODULE_AUTHOR(DRIVER_AUTHOR); 700 MODULE_DESCRIPTION(DRIVER_DESC); 701 702 /* 703 * The following describes what I learned from studying the old 704 * ark3116.c driver, disassembling the windows driver, and some lucky 705 * guesses. Since I do not have any datasheet or other 706 * documentation, inaccuracies are almost guaranteed. 707 * 708 * Some specs for the ARK3116 can be found here: 709 * http://web.archive.org/web/20060318000438/ 710 * www.arkmicro.com/en/products/view.php?id=10 711 * On that page, 2 GPIO pins are mentioned: I assume these are the 712 * OUT1 and OUT2 pins of the UART, so I added support for those 713 * through the MCR. Since the pins are not available on my hardware, 714 * I could not verify this. 715 * Also, it states there is "on-chip hardware flow control". I have 716 * discovered how to enable that. Unfortunately, I do not know how to 717 * enable XON/XOFF (software) flow control, which would need support 718 * from the chip as well to work. Because of the wording on the web 719 * page there is a real possibility the chip simply does not support 720 * software flow control. 721 * 722 * I got my ark3116 as part of a mobile phone adapter cable. On the 723 * PCB, the following numbered contacts are present: 724 * 725 * 1:- +5V 726 * 2:o DTR 727 * 3:i RX 728 * 4:i DCD 729 * 5:o RTS 730 * 6:o TX 731 * 7:i RI 732 * 8:i DSR 733 * 10:- 0V 734 * 11:i CTS 735 * 736 * On my chip, all signals seem to be 3.3V, but 5V tolerant. But that 737 * may be different for the one you have ;-). 738 * 739 * The windows driver limits the registers to 0-F, so I assume there 740 * are actually 16 present on the device. 741 * 742 * On an UART interrupt, 4 bytes of data come in on the interrupt 743 * endpoint. The bytes are 0xe8 IIR LSR MSR. 744 * 745 * The baudrate seems to be generated from the 12MHz crystal, using 746 * 4-times subsampling. So quot=12e6/(4*baud). Also see description 747 * of register E. 748 * 749 * Registers 0-7: 750 * These seem to be the same as for a regular 16450. The FCR is set 751 * to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between 752 * the UART and the USB bridge/DMA engine. 753 * 754 * Register 8: 755 * By trial and error, I found out that bit 0 enables hardware CTS, 756 * stopping TX when CTS is +5V. Bit 1 does the same for RTS, making 757 * RTS +5V when the 3116 cannot transfer the data to the USB bus 758 * (verified by disabling the reading URB). Note that as far as I can 759 * tell, the windows driver does NOT use this, so there might be some 760 * hardware bug or something. 761 * 762 * According to a patch provided here 763 * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used 764 * as an IrDA dongle. Since I do not have such a thing, I could not 765 * investigate that aspect. However, I can speculate ;-). 766 * 767 * - IrDA encodes data differently than RS232. Most likely, one of 768 * the bits in registers 9..E enables the IR ENDEC (encoder/decoder). 769 * - Depending on the IR transceiver, the input and output need to be 770 * inverted, so there are probably bits for that as well. 771 * - IrDA is half-duplex, so there should be a bit for selecting that. 772 * 773 * This still leaves at least two registers unaccounted for. Perhaps 774 * The chip can do XON/XOFF or CRC in HW? 775 * 776 * Register 9: 777 * Set to 0x00 for IrDA, when the baudrate is initialised. 778 * 779 * Register A: 780 * Set to 0x01 for IrDA, at init. 781 * 782 * Register B: 783 * Set to 0x01 for IrDA, 0x00 for RS232, at init. 784 * 785 * Register C: 786 * Set to 00 for IrDA, at init. 787 * 788 * Register D: 789 * Set to 0x41 for IrDA, at init. 790 * 791 * Register E: 792 * Somekind of baudrate override. The windows driver seems to set 793 * this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600. 794 * Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer, 795 * it could be somekind of subdivisor thingy. 796 * However,it does not seem to do anything: selecting 921600 (divisor 3, 797 * reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would 798 * work, but they don't. 799 * 800 * Register F: unknown 801 */ 802