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/init.h> 27 #include <linux/ioctl.h> 28 #include <linux/tty.h> 29 #include <linux/slab.h> 30 #include <linux/tty_flip.h> 31 #include <linux/module.h> 32 #include <linux/usb.h> 33 #include <linux/usb/serial.h> 34 #include <linux/serial.h> 35 #include <linux/serial_reg.h> 36 #include <linux/uaccess.h> 37 #include <linux/mutex.h> 38 #include <linux/spinlock.h> 39 40 #define DRIVER_AUTHOR "Bart Hartgers <bart.hartgers+ark3116@gmail.com>" 41 #define DRIVER_DESC "USB ARK3116 serial/IrDA driver" 42 #define DRIVER_DEV_DESC "ARK3116 RS232/IrDA" 43 #define DRIVER_NAME "ark3116" 44 45 /* usb timeout of 1 second */ 46 #define ARK_TIMEOUT 1000 47 48 static const struct usb_device_id id_table[] = { 49 { USB_DEVICE(0x6547, 0x0232) }, 50 { USB_DEVICE(0x18ec, 0x3118) }, /* USB to IrDA adapter */ 51 { }, 52 }; 53 MODULE_DEVICE_TABLE(usb, id_table); 54 55 static int is_irda(struct usb_serial *serial) 56 { 57 struct usb_device *dev = serial->dev; 58 if (le16_to_cpu(dev->descriptor.idVendor) == 0x18ec && 59 le16_to_cpu(dev->descriptor.idProduct) == 0x3118) 60 return 1; 61 return 0; 62 } 63 64 struct ark3116_private { 65 int irda; /* 1 for irda device */ 66 67 /* protects hw register updates */ 68 struct mutex hw_lock; 69 70 int quot; /* baudrate divisor */ 71 __u32 lcr; /* line control register value */ 72 __u32 hcr; /* handshake control register (0x8) 73 * value */ 74 __u32 mcr; /* modem contol register value */ 75 76 /* protects the status values below */ 77 spinlock_t status_lock; 78 __u32 msr; /* modem status register value */ 79 __u32 lsr; /* line status register value */ 80 }; 81 82 static int ark3116_write_reg(struct usb_serial *serial, 83 unsigned reg, __u8 val) 84 { 85 int result; 86 /* 0xfe 0x40 are magic values taken from original driver */ 87 result = usb_control_msg(serial->dev, 88 usb_sndctrlpipe(serial->dev, 0), 89 0xfe, 0x40, val, reg, 90 NULL, 0, ARK_TIMEOUT); 91 return result; 92 } 93 94 static int ark3116_read_reg(struct usb_serial *serial, 95 unsigned reg, unsigned char *buf) 96 { 97 int result; 98 /* 0xfe 0xc0 are magic values taken from original driver */ 99 result = usb_control_msg(serial->dev, 100 usb_rcvctrlpipe(serial->dev, 0), 101 0xfe, 0xc0, 0, reg, 102 buf, 1, ARK_TIMEOUT); 103 if (result < 0) 104 return result; 105 else 106 return buf[0]; 107 } 108 109 static inline int calc_divisor(int bps) 110 { 111 /* Original ark3116 made some exceptions in rounding here 112 * because windows did the same. Assume that is not really 113 * necessary. 114 * Crystal is 12MHz, probably because of USB, but we divide by 4? 115 */ 116 return (12000000 + 2*bps) / (4*bps); 117 } 118 119 static int ark3116_attach(struct usb_serial *serial) 120 { 121 /* make sure we have our end-points */ 122 if ((serial->num_bulk_in == 0) || 123 (serial->num_bulk_out == 0) || 124 (serial->num_interrupt_in == 0)) { 125 dev_err(&serial->dev->dev, 126 "%s - missing endpoint - " 127 "bulk in: %d, bulk out: %d, int in %d\n", 128 KBUILD_MODNAME, 129 serial->num_bulk_in, 130 serial->num_bulk_out, 131 serial->num_interrupt_in); 132 return -EINVAL; 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(&serial->dev->dev, 191 "%s using %s mode\n", 192 KBUILD_MODNAME, 193 priv->irda ? "IrDA" : "RS232"); 194 return 0; 195 } 196 197 static int ark3116_port_remove(struct usb_serial_port *port) 198 { 199 struct ark3116_private *priv = usb_get_serial_port_data(port); 200 201 /* device is closed, so URBs and DMA should be down */ 202 mutex_destroy(&priv->hw_lock); 203 kfree(priv); 204 205 return 0; 206 } 207 208 static void ark3116_init_termios(struct tty_struct *tty) 209 { 210 struct ktermios *termios = &tty->termios; 211 *termios = tty_std_termios; 212 termios->c_cflag = B9600 | CS8 213 | CREAD | HUPCL | CLOCAL; 214 termios->c_ispeed = 9600; 215 termios->c_ospeed = 9600; 216 } 217 218 static void ark3116_set_termios(struct tty_struct *tty, 219 struct usb_serial_port *port, 220 struct ktermios *old_termios) 221 { 222 struct usb_serial *serial = port->serial; 223 struct ark3116_private *priv = usb_get_serial_port_data(port); 224 struct ktermios *termios = &tty->termios; 225 unsigned int cflag = termios->c_cflag; 226 int bps = tty_get_baud_rate(tty); 227 int quot; 228 __u8 lcr, hcr, eval; 229 230 /* set data bit count */ 231 switch (cflag & CSIZE) { 232 case CS5: 233 lcr = UART_LCR_WLEN5; 234 break; 235 case CS6: 236 lcr = UART_LCR_WLEN6; 237 break; 238 case CS7: 239 lcr = UART_LCR_WLEN7; 240 break; 241 default: 242 case CS8: 243 lcr = UART_LCR_WLEN8; 244 break; 245 } 246 if (cflag & CSTOPB) 247 lcr |= UART_LCR_STOP; 248 if (cflag & PARENB) 249 lcr |= UART_LCR_PARITY; 250 if (!(cflag & PARODD)) 251 lcr |= UART_LCR_EPAR; 252 #ifdef CMSPAR 253 if (cflag & CMSPAR) 254 lcr |= UART_LCR_SPAR; 255 #endif 256 /* handshake control */ 257 hcr = (cflag & CRTSCTS) ? 0x03 : 0x00; 258 259 /* calc baudrate */ 260 dev_dbg(&port->dev, "%s - setting bps to %d\n", __func__, bps); 261 eval = 0; 262 switch (bps) { 263 case 0: 264 quot = calc_divisor(9600); 265 break; 266 default: 267 if ((bps < 75) || (bps > 3000000)) 268 bps = 9600; 269 quot = calc_divisor(bps); 270 break; 271 case 460800: 272 eval = 1; 273 quot = calc_divisor(bps); 274 break; 275 case 921600: 276 eval = 2; 277 quot = calc_divisor(bps); 278 break; 279 } 280 281 /* Update state: synchronize */ 282 mutex_lock(&priv->hw_lock); 283 284 /* keep old LCR_SBC bit */ 285 lcr |= (priv->lcr & UART_LCR_SBC); 286 287 dev_dbg(&port->dev, "%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d\n", 288 __func__, hcr, lcr, quot); 289 290 /* handshake control */ 291 if (priv->hcr != hcr) { 292 priv->hcr = hcr; 293 ark3116_write_reg(serial, 0x8, hcr); 294 } 295 296 /* baudrate */ 297 if (priv->quot != quot) { 298 priv->quot = quot; 299 priv->lcr = lcr; /* need to write lcr anyway */ 300 301 /* disable DMA since transmit/receive is 302 * shadowed by UART_DLL 303 */ 304 ark3116_write_reg(serial, UART_FCR, 0); 305 306 ark3116_write_reg(serial, UART_LCR, 307 lcr|UART_LCR_DLAB); 308 ark3116_write_reg(serial, UART_DLL, quot & 0xff); 309 ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff); 310 311 /* restore lcr */ 312 ark3116_write_reg(serial, UART_LCR, lcr); 313 /* magic baudrate thingy: not sure what it does, 314 * but windows does this as well. 315 */ 316 ark3116_write_reg(serial, 0xe, eval); 317 318 /* enable DMA */ 319 ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT); 320 } else if (priv->lcr != lcr) { 321 priv->lcr = lcr; 322 ark3116_write_reg(serial, UART_LCR, lcr); 323 } 324 325 mutex_unlock(&priv->hw_lock); 326 327 /* check for software flow control */ 328 if (I_IXOFF(tty) || I_IXON(tty)) { 329 dev_warn(&serial->dev->dev, 330 "%s: don't know how to do software flow control\n", 331 KBUILD_MODNAME); 332 } 333 334 /* Don't rewrite B0 */ 335 if (tty_termios_baud_rate(termios)) 336 tty_termios_encode_baud_rate(termios, bps, bps); 337 } 338 339 static void ark3116_close(struct usb_serial_port *port) 340 { 341 struct usb_serial *serial = port->serial; 342 343 /* disable DMA */ 344 ark3116_write_reg(serial, UART_FCR, 0); 345 346 /* deactivate interrupts */ 347 ark3116_write_reg(serial, UART_IER, 0); 348 349 usb_serial_generic_close(port); 350 if (serial->num_interrupt_in) 351 usb_kill_urb(port->interrupt_in_urb); 352 } 353 354 static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port) 355 { 356 struct ark3116_private *priv = usb_get_serial_port_data(port); 357 struct usb_serial *serial = port->serial; 358 unsigned char *buf; 359 int result; 360 361 buf = kmalloc(1, GFP_KERNEL); 362 if (buf == NULL) 363 return -ENOMEM; 364 365 result = usb_serial_generic_open(tty, port); 366 if (result) { 367 dev_dbg(&port->dev, 368 "%s - usb_serial_generic_open failed: %d\n", 369 __func__, result); 370 goto err_out; 371 } 372 373 /* remove any data still left: also clears error state */ 374 ark3116_read_reg(serial, UART_RX, buf); 375 376 /* read modem status */ 377 priv->msr = ark3116_read_reg(serial, UART_MSR, buf); 378 /* read line status */ 379 priv->lsr = ark3116_read_reg(serial, UART_LSR, buf); 380 381 result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL); 382 if (result) { 383 dev_err(&port->dev, "submit irq_in urb failed %d\n", 384 result); 385 ark3116_close(port); 386 goto err_out; 387 } 388 389 /* activate interrupts */ 390 ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI); 391 392 /* enable DMA */ 393 ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT); 394 395 /* setup termios */ 396 if (tty) 397 ark3116_set_termios(tty, port, NULL); 398 399 err_out: 400 kfree(buf); 401 return result; 402 } 403 404 static int ark3116_ioctl(struct tty_struct *tty, 405 unsigned int cmd, unsigned long arg) 406 { 407 struct usb_serial_port *port = tty->driver_data; 408 struct serial_struct serstruct; 409 void __user *user_arg = (void __user *)arg; 410 411 switch (cmd) { 412 case TIOCGSERIAL: 413 /* XXX: Some of these values are probably wrong. */ 414 memset(&serstruct, 0, sizeof(serstruct)); 415 serstruct.type = PORT_16654; 416 serstruct.line = port->minor; 417 serstruct.port = port->port_number; 418 serstruct.custom_divisor = 0; 419 serstruct.baud_base = 460800; 420 421 if (copy_to_user(user_arg, &serstruct, sizeof(serstruct))) 422 return -EFAULT; 423 424 return 0; 425 case TIOCSSERIAL: 426 if (copy_from_user(&serstruct, user_arg, sizeof(serstruct))) 427 return -EFAULT; 428 return 0; 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(&urb->dev->dev, 607 "%s - Error %d submitting interrupt urb\n", 608 __func__, result); 609 } 610 611 612 /* Data comes in via the bulk (data) URB, erors/interrupts via the int URB. 613 * This means that we cannot be sure which data byte has an associated error 614 * condition, so we report an error for all data in the next bulk read. 615 * 616 * Actually, there might even be a window between the bulk data leaving the 617 * ark and reading/resetting the lsr in the read_bulk_callback where an 618 * interrupt for the next data block could come in. 619 * Without somekind of ordering on the ark, we would have to report the 620 * error for the next block of data as well... 621 * For now, let's pretend this can't happen. 622 */ 623 static void ark3116_process_read_urb(struct urb *urb) 624 { 625 struct usb_serial_port *port = urb->context; 626 struct ark3116_private *priv = usb_get_serial_port_data(port); 627 unsigned char *data = urb->transfer_buffer; 628 char tty_flag = TTY_NORMAL; 629 unsigned long flags; 630 __u32 lsr; 631 632 /* update line status */ 633 spin_lock_irqsave(&priv->status_lock, flags); 634 lsr = priv->lsr; 635 priv->lsr &= ~UART_LSR_BRK_ERROR_BITS; 636 spin_unlock_irqrestore(&priv->status_lock, flags); 637 638 if (!urb->actual_length) 639 return; 640 641 if (lsr & UART_LSR_BRK_ERROR_BITS) { 642 if (lsr & UART_LSR_BI) 643 tty_flag = TTY_BREAK; 644 else if (lsr & UART_LSR_PE) 645 tty_flag = TTY_PARITY; 646 else if (lsr & UART_LSR_FE) 647 tty_flag = TTY_FRAME; 648 649 /* overrun is special, not associated with a char */ 650 if (lsr & UART_LSR_OE) 651 tty_insert_flip_char(&port->port, 0, TTY_OVERRUN); 652 } 653 tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag, 654 urb->actual_length); 655 tty_flip_buffer_push(&port->port); 656 } 657 658 static struct usb_serial_driver ark3116_device = { 659 .driver = { 660 .owner = THIS_MODULE, 661 .name = "ark3116", 662 }, 663 .id_table = id_table, 664 .num_ports = 1, 665 .attach = ark3116_attach, 666 .port_probe = ark3116_port_probe, 667 .port_remove = ark3116_port_remove, 668 .set_termios = ark3116_set_termios, 669 .init_termios = ark3116_init_termios, 670 .ioctl = ark3116_ioctl, 671 .tiocmget = ark3116_tiocmget, 672 .tiocmset = ark3116_tiocmset, 673 .tiocmiwait = usb_serial_generic_tiocmiwait, 674 .get_icount = usb_serial_generic_get_icount, 675 .open = ark3116_open, 676 .close = ark3116_close, 677 .break_ctl = ark3116_break_ctl, 678 .read_int_callback = ark3116_read_int_callback, 679 .process_read_urb = ark3116_process_read_urb, 680 }; 681 682 static struct usb_serial_driver * const serial_drivers[] = { 683 &ark3116_device, NULL 684 }; 685 686 module_usb_serial_driver(serial_drivers, id_table); 687 688 MODULE_LICENSE("GPL"); 689 690 MODULE_AUTHOR(DRIVER_AUTHOR); 691 MODULE_DESCRIPTION(DRIVER_DESC); 692 693 /* 694 * The following describes what I learned from studying the old 695 * ark3116.c driver, disassembling the windows driver, and some lucky 696 * guesses. Since I do not have any datasheet or other 697 * documentation, inaccuracies are almost guaranteed. 698 * 699 * Some specs for the ARK3116 can be found here: 700 * http://web.archive.org/web/20060318000438/ 701 * www.arkmicro.com/en/products/view.php?id=10 702 * On that page, 2 GPIO pins are mentioned: I assume these are the 703 * OUT1 and OUT2 pins of the UART, so I added support for those 704 * through the MCR. Since the pins are not available on my hardware, 705 * I could not verify this. 706 * Also, it states there is "on-chip hardware flow control". I have 707 * discovered how to enable that. Unfortunately, I do not know how to 708 * enable XON/XOFF (software) flow control, which would need support 709 * from the chip as well to work. Because of the wording on the web 710 * page there is a real possibility the chip simply does not support 711 * software flow control. 712 * 713 * I got my ark3116 as part of a mobile phone adapter cable. On the 714 * PCB, the following numbered contacts are present: 715 * 716 * 1:- +5V 717 * 2:o DTR 718 * 3:i RX 719 * 4:i DCD 720 * 5:o RTS 721 * 6:o TX 722 * 7:i RI 723 * 8:i DSR 724 * 10:- 0V 725 * 11:i CTS 726 * 727 * On my chip, all signals seem to be 3.3V, but 5V tolerant. But that 728 * may be different for the one you have ;-). 729 * 730 * The windows driver limits the registers to 0-F, so I assume there 731 * are actually 16 present on the device. 732 * 733 * On an UART interrupt, 4 bytes of data come in on the interrupt 734 * endpoint. The bytes are 0xe8 IIR LSR MSR. 735 * 736 * The baudrate seems to be generated from the 12MHz crystal, using 737 * 4-times subsampling. So quot=12e6/(4*baud). Also see description 738 * of register E. 739 * 740 * Registers 0-7: 741 * These seem to be the same as for a regular 16450. The FCR is set 742 * to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between 743 * the UART and the USB bridge/DMA engine. 744 * 745 * Register 8: 746 * By trial and error, I found out that bit 0 enables hardware CTS, 747 * stopping TX when CTS is +5V. Bit 1 does the same for RTS, making 748 * RTS +5V when the 3116 cannot transfer the data to the USB bus 749 * (verified by disabling the reading URB). Note that as far as I can 750 * tell, the windows driver does NOT use this, so there might be some 751 * hardware bug or something. 752 * 753 * According to a patch provided here 754 * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used 755 * as an IrDA dongle. Since I do not have such a thing, I could not 756 * investigate that aspect. However, I can speculate ;-). 757 * 758 * - IrDA encodes data differently than RS232. Most likely, one of 759 * the bits in registers 9..E enables the IR ENDEC (encoder/decoder). 760 * - Depending on the IR transceiver, the input and output need to be 761 * inverted, so there are probably bits for that as well. 762 * - IrDA is half-duplex, so there should be a bit for selecting that. 763 * 764 * This still leaves at least two registers unaccounted for. Perhaps 765 * The chip can do XON/XOFF or CRC in HW? 766 * 767 * Register 9: 768 * Set to 0x00 for IrDA, when the baudrate is initialised. 769 * 770 * Register A: 771 * Set to 0x01 for IrDA, at init. 772 * 773 * Register B: 774 * Set to 0x01 for IrDA, 0x00 for RS232, at init. 775 * 776 * Register C: 777 * Set to 00 for IrDA, at init. 778 * 779 * Register D: 780 * Set to 0x41 for IrDA, at init. 781 * 782 * Register E: 783 * Somekind of baudrate override. The windows driver seems to set 784 * this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600. 785 * Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer, 786 * it could be somekind of subdivisor thingy. 787 * However,it does not seem to do anything: selecting 921600 (divisor 3, 788 * reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would 789 * work, but they don't. 790 * 791 * Register F: unknown 792 */ 793