drivers/usb/serial/ark3116.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2009 by Bart Hartgers (bart.hartgers+ark3116@gmail.com)
   4  * Original version:
   5  * Copyright (C) 2006
   6  *   Simon Schulz (ark3116_driver <at> auctionant.de)
   7  *
   8  * ark3116
   9  * - implements a driver for the arkmicro ark3116 chipset (vendor=0x6547,
  10  *   productid=0x0232) (used in a datacable called KQ-U8A)
  11  *
  12  * Supports full modem status lines, break, hardware flow control. Does not
  13  * support software flow control, since I do not know how to enable it in hw.
  14  *
  15  * This driver is a essentially new implementation. I initially dug
  16  * into the old ark3116.c driver and suddenly realized the ark3116 is
  17  * a 16450 with a USB interface glued to it. See comments at the
  18  * bottom of this file.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/ioctl.h>
  23 #include <linux/tty.h>
  24 #include <linux/slab.h>
  25 #include <linux/tty_flip.h>
  26 #include <linux/module.h>
  27 #include <linux/usb.h>
  28 #include <linux/usb/serial.h>
  29 #include <linux/serial.h>
  30 #include <linux/serial_reg.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/mutex.h>
  33 #include <linux/spinlock.h>
  34
  35 #define DRIVER_AUTHOR "Bart Hartgers <bart.hartgers+ark3116@gmail.com>"
  36 #define DRIVER_DESC "USB ARK3116 serial/IrDA driver"
  37 #define DRIVER_DEV_DESC "ARK3116 RS232/IrDA"
  38 #define DRIVER_NAME "ark3116"
  39
  40 /* usb timeout of 1 second */
  41 #define ARK_TIMEOUT 1000
  42
  43 static const struct usb_device_id id_table[] = {
  44         { USB_DEVICE(0x6547, 0x0232) },
  45         { USB_DEVICE(0x18ec, 0x3118) },         /* USB to IrDA adapter */
  46         { },
  47 };
  48 MODULE_DEVICE_TABLE(usb, id_table);
  49
  50 static int is_irda(struct usb_serial *serial)
  51 {
  52         struct usb_device *dev = serial->dev;
  53         if (le16_to_cpu(dev->descriptor.idVendor) == 0x18ec &&
  54                         le16_to_cpu(dev->descriptor.idProduct) == 0x3118)
  55                 return 1;
  56         return 0;
  57 }
  58
  59 struct ark3116_private {
  60         int                     irda;   /* 1 for irda device */
  61
  62         /* protects hw register updates */
  63         struct mutex            hw_lock;
  64
  65         int                     quot;   /* baudrate divisor */
  66         __u32                   lcr;    /* line control register value */
  67         __u32                   hcr;    /* handshake control register (0x8)
  68                                          * value */
  69         __u32                   mcr;    /* modem control register value */
  70
  71         /* protects the status values below */
  72         spinlock_t              status_lock;
  73         __u32                   msr;    /* modem status register value */
  74         __u32                   lsr;    /* line status register value */
  75 };
  76
  77 static int ark3116_write_reg(struct usb_serial *serial,
  78                              unsigned reg, __u8 val)
  79 {
  80         int result;
  81          /* 0xfe 0x40 are magic values taken from original driver */
  82         result = usb_control_msg(serial->dev,
  83                                  usb_sndctrlpipe(serial->dev, 0),
  84                                  0xfe, 0x40, val, reg,
  85                                  NULL, 0, ARK_TIMEOUT);
  86         if (result)
  87                 return result;
  88
  89         return 0;
  90 }
  91
  92 static int ark3116_read_reg(struct usb_serial *serial,
  93                             unsigned reg, unsigned char *buf)
  94 {
  95         int result;
  96         /* 0xfe 0xc0 are magic values taken from original driver */
  97         result = usb_control_msg(serial->dev,
  98                                  usb_rcvctrlpipe(serial->dev, 0),
  99                                  0xfe, 0xc0, 0, reg,
 100                                  buf, 1, ARK_TIMEOUT);
 101         if (result < 1) {
 102                 dev_err(&serial->interface->dev,
 103                                 "failed to read register %u: %d\n",
 104                                 reg, result);
 105                 if (result >= 0)
 106                         result = -EIO;
 107
 108                 return result;
 109         }
 110
 111         return 0;
 112 }
 113
 114 static inline int calc_divisor(int bps)
 115 {
 116         /* Original ark3116 made some exceptions in rounding here
 117          * because windows did the same. Assume that is not really
 118          * necessary.
 119          * Crystal is 12MHz, probably because of USB, but we divide by 4?
 120          */
 121         return (12000000 + 2*bps) / (4*bps);
 122 }
 123
 124 static int ark3116_port_probe(struct usb_serial_port *port)
 125 {
 126         struct usb_serial *serial = port->serial;
 127         struct ark3116_private *priv;
 128
 129         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 130         if (!priv)
 131                 return -ENOMEM;
 132
 133         mutex_init(&priv->hw_lock);
 134         spin_lock_init(&priv->status_lock);
 135
 136         priv->irda = is_irda(serial);
 137
 138         usb_set_serial_port_data(port, priv);
 139
 140         /* setup the hardware */
 141         ark3116_write_reg(serial, UART_IER, 0);
 142         /* disable DMA */
 143         ark3116_write_reg(serial, UART_FCR, 0);
 144         /* handshake control */
 145         priv->hcr = 0;
 146         ark3116_write_reg(serial, 0x8     , 0);
 147         /* modem control */
 148         priv->mcr = 0;
 149         ark3116_write_reg(serial, UART_MCR, 0);
 150
 151         if (!(priv->irda)) {
 152                 ark3116_write_reg(serial, 0xb , 0);
 153         } else {
 154                 ark3116_write_reg(serial, 0xb , 1);
 155                 ark3116_write_reg(serial, 0xc , 0);
 156                 ark3116_write_reg(serial, 0xd , 0x41);
 157                 ark3116_write_reg(serial, 0xa , 1);
 158         }
 159
 160         /* setup baudrate */
 161         ark3116_write_reg(serial, UART_LCR, UART_LCR_DLAB);
 162
 163         /* setup for 9600 8N1 */
 164         priv->quot = calc_divisor(9600);
 165         ark3116_write_reg(serial, UART_DLL, priv->quot & 0xff);
 166         ark3116_write_reg(serial, UART_DLM, (priv->quot>>8) & 0xff);
 167
 168         priv->lcr = UART_LCR_WLEN8;
 169         ark3116_write_reg(serial, UART_LCR, UART_LCR_WLEN8);
 170
 171         ark3116_write_reg(serial, 0xe, 0);
 172
 173         if (priv->irda)
 174                 ark3116_write_reg(serial, 0x9, 0);
 175
 176         dev_info(&port->dev, "using %s mode\n", priv->irda ? "IrDA" : "RS232");
 177
 178         return 0;
 179 }
 180
 181 static int ark3116_port_remove(struct usb_serial_port *port)
 182 {
 183         struct ark3116_private *priv = usb_get_serial_port_data(port);
 184
 185         /* device is closed, so URBs and DMA should be down */
 186         mutex_destroy(&priv->hw_lock);
 187         kfree(priv);
 188
 189         return 0;
 190 }
 191
 192 static void ark3116_init_termios(struct tty_struct *tty)
 193 {
 194         struct ktermios *termios = &tty->termios;
 195         *termios = tty_std_termios;
 196         termios->c_cflag = B9600 | CS8
 197                                       | CREAD | HUPCL | CLOCAL;
 198         termios->c_ispeed = 9600;
 199         termios->c_ospeed = 9600;
 200 }
 201
 202 static void ark3116_set_termios(struct tty_struct *tty,
 203                                 struct usb_serial_port *port,
 204                                 struct ktermios *old_termios)
 205 {
 206         struct usb_serial *serial = port->serial;
 207         struct ark3116_private *priv = usb_get_serial_port_data(port);
 208         struct ktermios *termios = &tty->termios;
 209         unsigned int cflag = termios->c_cflag;
 210         int bps = tty_get_baud_rate(tty);
 211         int quot;
 212         __u8 lcr, hcr, eval;
 213
 214         /* set data bit count */
 215         switch (cflag & CSIZE) {
 216         case CS5:
 217                 lcr = UART_LCR_WLEN5;
 218                 break;
 219         case CS6:
 220                 lcr = UART_LCR_WLEN6;
 221                 break;
 222         case CS7:
 223                 lcr = UART_LCR_WLEN7;
 224                 break;
 225         default:
 226         case CS8:
 227                 lcr = UART_LCR_WLEN8;
 228                 break;
 229         }
 230         if (cflag & CSTOPB)
 231                 lcr |= UART_LCR_STOP;
 232         if (cflag & PARENB)
 233                 lcr |= UART_LCR_PARITY;
 234         if (!(cflag & PARODD))
 235                 lcr |= UART_LCR_EPAR;
 236 #ifdef CMSPAR
 237         if (cflag & CMSPAR)
 238                 lcr |= UART_LCR_SPAR;
 239 #endif
 240         /* handshake control */
 241         hcr = (cflag & CRTSCTS) ? 0x03 : 0x00;
 242
 243         /* calc baudrate */
 244         dev_dbg(&port->dev, "%s - setting bps to %d\n", __func__, bps);
 245         eval = 0;
 246         switch (bps) {
 247         case 0:
 248                 quot = calc_divisor(9600);
 249                 break;
 250         default:
 251                 if ((bps < 75) || (bps > 3000000))
 252                         bps = 9600;
 253                 quot = calc_divisor(bps);
 254                 break;
 255         case 460800:
 256                 eval = 1;
 257                 quot = calc_divisor(bps);
 258                 break;
 259         case 921600:
 260                 eval = 2;
 261                 quot = calc_divisor(bps);
 262                 break;
 263         }
 264
 265         /* Update state: synchronize */
 266         mutex_lock(&priv->hw_lock);
 267
 268         /* keep old LCR_SBC bit */
 269         lcr |= (priv->lcr & UART_LCR_SBC);
 270
 271         dev_dbg(&port->dev, "%s - setting hcr:0x%02x,lcr:0x%02x,quot:%d\n",
 272                 __func__, hcr, lcr, quot);
 273
 274         /* handshake control */
 275         if (priv->hcr != hcr) {
 276                 priv->hcr = hcr;
 277                 ark3116_write_reg(serial, 0x8, hcr);
 278         }
 279
 280         /* baudrate */
 281         if (priv->quot != quot) {
 282                 priv->quot = quot;
 283                 priv->lcr = lcr; /* need to write lcr anyway */
 284
 285                 /* disable DMA since transmit/receive is
 286                  * shadowed by UART_DLL
 287                  */
 288                 ark3116_write_reg(serial, UART_FCR, 0);
 289
 290                 ark3116_write_reg(serial, UART_LCR,
 291                                   lcr|UART_LCR_DLAB);
 292                 ark3116_write_reg(serial, UART_DLL, quot & 0xff);
 293                 ark3116_write_reg(serial, UART_DLM, (quot>>8) & 0xff);
 294
 295                 /* restore lcr */
 296                 ark3116_write_reg(serial, UART_LCR, lcr);
 297                 /* magic baudrate thingy: not sure what it does,
 298                  * but windows does this as well.
 299                  */
 300                 ark3116_write_reg(serial, 0xe, eval);
 301
 302                 /* enable DMA */
 303                 ark3116_write_reg(serial, UART_FCR, UART_FCR_DMA_SELECT);
 304         } else if (priv->lcr != lcr) {
 305                 priv->lcr = lcr;
 306                 ark3116_write_reg(serial, UART_LCR, lcr);
 307         }
 308
 309         mutex_unlock(&priv->hw_lock);
 310
 311         /* check for software flow control */
 312         if (I_IXOFF(tty) || I_IXON(tty)) {
 313                 dev_warn(&port->dev,
 314                                 "software flow control not implemented\n");
 315         }
 316
 317         /* Don't rewrite B0 */
 318         if (tty_termios_baud_rate(termios))
 319                 tty_termios_encode_baud_rate(termios, bps, bps);
 320 }
 321
 322 static void ark3116_close(struct usb_serial_port *port)
 323 {
 324         struct usb_serial *serial = port->serial;
 325
 326         /* disable DMA */
 327         ark3116_write_reg(serial, UART_FCR, 0);
 328
 329         /* deactivate interrupts */
 330         ark3116_write_reg(serial, UART_IER, 0);
 331
 332         usb_serial_generic_close(port);
 333
 334         usb_kill_urb(port->interrupt_in_urb);
 335 }
 336
 337 static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port)
 338 {
 339         struct ark3116_private *priv = usb_get_serial_port_data(port);
 340         struct usb_serial *serial = port->serial;
 341         unsigned char *buf;
 342         int result;
 343
 344         buf = kmalloc(1, GFP_KERNEL);
 345         if (buf == NULL)
 346                 return -ENOMEM;
 347
 348         result = usb_serial_generic_open(tty, port);
 349         if (result) {
 350                 dev_dbg(&port->dev,
 351                         "%s - usb_serial_generic_open failed: %d\n",
 352                         __func__, result);
 353                 goto err_free;
 354         }
 355
 356         /* remove any data still left: also clears error state */
 357         ark3116_read_reg(serial, UART_RX, buf);
 358
 359         /* read modem status */
 360         result = ark3116_read_reg(serial, UART_MSR, buf);
 361         if (result)
 362                 goto err_close;
 363         priv->msr = *buf;
 364
 365         /* read line status */
 366         result = ark3116_read_reg(serial, UART_LSR, buf);
 367         if (result)
 368                 goto err_close;
 369         priv->lsr = *buf;
 370
 371         result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 372         if (result) {
 373                 dev_err(&port->dev, "submit irq_in urb failed %d\n",
 374                         result);
 375                 goto err_close;
 376         }
 377
 378         /* activate interrupts */
 379         ark3116_write_reg(port->serial, UART_IER, UART_IER_MSI|UART_IER_RLSI);
 380
 381         /* enable DMA */
 382         ark3116_write_reg(port->serial, UART_FCR, UART_FCR_DMA_SELECT);
 383
 384         /* setup termios */
 385         if (tty)
 386                 ark3116_set_termios(tty, port, NULL);
 387
 388         kfree(buf);
 389
 390         return 0;
 391
 392 err_close:
 393         usb_serial_generic_close(port);
 394 err_free:
 395         kfree(buf);
 396
 397         return result;
 398 }
 399
 400 static int ark3116_get_serial_info(struct tty_struct *tty,
 401                         struct serial_struct *ss)
 402 {
 403         struct usb_serial_port *port = tty->driver_data;
 404
 405         ss->type = PORT_16654;
 406         ss->line = port->minor;
 407         ss->port = port->port_number;
 408         ss->baud_base = 460800;
 409         return 0;
 410 }
 411
 412 static int ark3116_tiocmget(struct tty_struct *tty)
 413 {
 414         struct usb_serial_port *port = tty->driver_data;
 415         struct ark3116_private *priv = usb_get_serial_port_data(port);
 416         __u32 status;
 417         __u32 ctrl;
 418         unsigned long flags;
 419
 420         mutex_lock(&priv->hw_lock);
 421         ctrl = priv->mcr;
 422         mutex_unlock(&priv->hw_lock);
 423
 424         spin_lock_irqsave(&priv->status_lock, flags);
 425         status = priv->msr;
 426         spin_unlock_irqrestore(&priv->status_lock, flags);
 427
 428         return  (status & UART_MSR_DSR  ? TIOCM_DSR  : 0) |
 429                 (status & UART_MSR_CTS  ? TIOCM_CTS  : 0) |
 430                 (status & UART_MSR_RI   ? TIOCM_RI   : 0) |
 431                 (status & UART_MSR_DCD  ? TIOCM_CD   : 0) |
 432                 (ctrl   & UART_MCR_DTR  ? TIOCM_DTR  : 0) |
 433                 (ctrl   & UART_MCR_RTS  ? TIOCM_RTS  : 0) |
 434                 (ctrl   & UART_MCR_OUT1 ? TIOCM_OUT1 : 0) |
 435                 (ctrl   & UART_MCR_OUT2 ? TIOCM_OUT2 : 0);
 436 }
 437
 438 static int ark3116_tiocmset(struct tty_struct *tty,
 439                         unsigned set, unsigned clr)
 440 {
 441         struct usb_serial_port *port = tty->driver_data;
 442         struct ark3116_private *priv = usb_get_serial_port_data(port);
 443
 444         /* we need to take the mutex here, to make sure that the value
 445          * in priv->mcr is actually the one that is in the hardware
 446          */
 447
 448         mutex_lock(&priv->hw_lock);
 449
 450         if (set & TIOCM_RTS)
 451                 priv->mcr |= UART_MCR_RTS;
 452         if (set & TIOCM_DTR)
 453                 priv->mcr |= UART_MCR_DTR;
 454         if (set & TIOCM_OUT1)
 455                 priv->mcr |= UART_MCR_OUT1;
 456         if (set & TIOCM_OUT2)
 457                 priv->mcr |= UART_MCR_OUT2;
 458         if (clr & TIOCM_RTS)
 459                 priv->mcr &= ~UART_MCR_RTS;
 460         if (clr & TIOCM_DTR)
 461                 priv->mcr &= ~UART_MCR_DTR;
 462         if (clr & TIOCM_OUT1)
 463                 priv->mcr &= ~UART_MCR_OUT1;
 464         if (clr & TIOCM_OUT2)
 465                 priv->mcr &= ~UART_MCR_OUT2;
 466
 467         ark3116_write_reg(port->serial, UART_MCR, priv->mcr);
 468
 469         mutex_unlock(&priv->hw_lock);
 470
 471         return 0;
 472 }
 473
 474 static void ark3116_break_ctl(struct tty_struct *tty, int break_state)
 475 {
 476         struct usb_serial_port *port = tty->driver_data;
 477         struct ark3116_private *priv = usb_get_serial_port_data(port);
 478
 479         /* LCR is also used for other things: protect access */
 480         mutex_lock(&priv->hw_lock);
 481
 482         if (break_state)
 483                 priv->lcr |= UART_LCR_SBC;
 484         else
 485                 priv->lcr &= ~UART_LCR_SBC;
 486
 487         ark3116_write_reg(port->serial, UART_LCR, priv->lcr);
 488
 489         mutex_unlock(&priv->hw_lock);
 490 }
 491
 492 static void ark3116_update_msr(struct usb_serial_port *port, __u8 msr)
 493 {
 494         struct ark3116_private *priv = usb_get_serial_port_data(port);
 495         unsigned long flags;
 496
 497         spin_lock_irqsave(&priv->status_lock, flags);
 498         priv->msr = msr;
 499         spin_unlock_irqrestore(&priv->status_lock, flags);
 500
 501         if (msr & UART_MSR_ANY_DELTA) {
 502                 /* update input line counters */
 503                 if (msr & UART_MSR_DCTS)
 504                         port->icount.cts++;
 505                 if (msr & UART_MSR_DDSR)
 506                         port->icount.dsr++;
 507                 if (msr & UART_MSR_DDCD)
 508                         port->icount.dcd++;
 509                 if (msr & UART_MSR_TERI)
 510                         port->icount.rng++;
 511                 wake_up_interruptible(&port->port.delta_msr_wait);
 512         }
 513 }
 514
 515 static void ark3116_update_lsr(struct usb_serial_port *port, __u8 lsr)
 516 {
 517         struct ark3116_private *priv = usb_get_serial_port_data(port);
 518         unsigned long flags;
 519
 520         spin_lock_irqsave(&priv->status_lock, flags);
 521         /* combine bits */
 522         priv->lsr |= lsr;
 523         spin_unlock_irqrestore(&priv->status_lock, flags);
 524
 525         if (lsr&UART_LSR_BRK_ERROR_BITS) {
 526                 if (lsr & UART_LSR_BI)
 527                         port->icount.brk++;
 528                 if (lsr & UART_LSR_FE)
 529                         port->icount.frame++;
 530                 if (lsr & UART_LSR_PE)
 531                         port->icount.parity++;
 532                 if (lsr & UART_LSR_OE)
 533                         port->icount.overrun++;
 534         }
 535 }
 536
 537 static void ark3116_read_int_callback(struct urb *urb)
 538 {
 539         struct usb_serial_port *port = urb->context;
 540         int status = urb->status;
 541         const __u8 *data = urb->transfer_buffer;
 542         int result;
 543
 544         switch (status) {
 545         case -ECONNRESET:
 546         case -ENOENT:
 547         case -ESHUTDOWN:
 548                 /* this urb is terminated, clean up */
 549                 dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
 550                         __func__, status);
 551                 return;
 552         default:
 553                 dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
 554                         __func__, status);
 555                 break;
 556         case 0: /* success */
 557                 /* discovered this by trail and error... */
 558                 if ((urb->actual_length == 4) && (data[0] == 0xe8)) {
 559                         const __u8 id = data[1]&UART_IIR_ID;
 560                         dev_dbg(&port->dev, "%s: iir=%02x\n", __func__, data[1]);
 561                         if (id == UART_IIR_MSI) {
 562                                 dev_dbg(&port->dev, "%s: msr=%02x\n",
 563                                         __func__, data[3]);
 564                                 ark3116_update_msr(port, data[3]);
 565                                 break;
 566                         } else if (id == UART_IIR_RLSI) {
 567                                 dev_dbg(&port->dev, "%s: lsr=%02x\n",
 568                                         __func__, data[2]);
 569                                 ark3116_update_lsr(port, data[2]);
 570                                 break;
 571                         }
 572                 }
 573                 /*
 574                  * Not sure what this data meant...
 575                  */
 576                 usb_serial_debug_data(&port->dev, __func__,
 577                                       urb->actual_length,
 578                                       urb->transfer_buffer);
 579                 break;
 580         }
 581
 582         result = usb_submit_urb(urb, GFP_ATOMIC);
 583         if (result)
 584                 dev_err(&port->dev, "failed to resubmit interrupt urb: %d\n",
 585                         result);
 586 }
 587
 588
 589 /* Data comes in via the bulk (data) URB, errors/interrupts via the int URB.
 590  * This means that we cannot be sure which data byte has an associated error
 591  * condition, so we report an error for all data in the next bulk read.
 592  *
 593  * Actually, there might even be a window between the bulk data leaving the
 594  * ark and reading/resetting the lsr in the read_bulk_callback where an
 595  * interrupt for the next data block could come in.
 596  * Without somekind of ordering on the ark, we would have to report the
 597  * error for the next block of data as well...
 598  * For now, let's pretend this can't happen.
 599  */
 600 static void ark3116_process_read_urb(struct urb *urb)
 601 {
 602         struct usb_serial_port *port = urb->context;
 603         struct ark3116_private *priv = usb_get_serial_port_data(port);
 604         unsigned char *data = urb->transfer_buffer;
 605         char tty_flag = TTY_NORMAL;
 606         unsigned long flags;
 607         __u32 lsr;
 608
 609         /* update line status */
 610         spin_lock_irqsave(&priv->status_lock, flags);
 611         lsr = priv->lsr;
 612         priv->lsr &= ~UART_LSR_BRK_ERROR_BITS;
 613         spin_unlock_irqrestore(&priv->status_lock, flags);
 614
 615         if (!urb->actual_length)
 616                 return;
 617
 618         if (lsr & UART_LSR_BRK_ERROR_BITS) {
 619                 if (lsr & UART_LSR_BI)
 620                         tty_flag = TTY_BREAK;
 621                 else if (lsr & UART_LSR_PE)
 622                         tty_flag = TTY_PARITY;
 623                 else if (lsr & UART_LSR_FE)
 624                         tty_flag = TTY_FRAME;
 625
 626                 /* overrun is special, not associated with a char */
 627                 if (lsr & UART_LSR_OE)
 628                         tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
 629         }
 630         tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag,
 631                                                         urb->actual_length);
 632         tty_flip_buffer_push(&port->port);
 633 }
 634
 635 static struct usb_serial_driver ark3116_device = {
 636         .driver = {
 637                 .owner =        THIS_MODULE,
 638                 .name =         "ark3116",
 639         },
 640         .id_table =             id_table,
 641         .num_ports =            1,
 642         .num_bulk_in =          1,
 643         .num_bulk_out =         1,
 644         .num_interrupt_in =     1,
 645         .port_probe =           ark3116_port_probe,
 646         .port_remove =          ark3116_port_remove,
 647         .set_termios =          ark3116_set_termios,
 648         .init_termios =         ark3116_init_termios,
 649         .get_serial =           ark3116_get_serial_info,
 650         .tiocmget =             ark3116_tiocmget,
 651         .tiocmset =             ark3116_tiocmset,
 652         .tiocmiwait =           usb_serial_generic_tiocmiwait,
 653         .get_icount =           usb_serial_generic_get_icount,
 654         .open =                 ark3116_open,
 655         .close =                ark3116_close,
 656         .break_ctl =            ark3116_break_ctl,
 657         .read_int_callback =    ark3116_read_int_callback,
 658         .process_read_urb =     ark3116_process_read_urb,
 659 };
 660
 661 static struct usb_serial_driver * const serial_drivers[] = {
 662         &ark3116_device, NULL
 663 };
 664
 665 module_usb_serial_driver(serial_drivers, id_table);
 666
 667 MODULE_LICENSE("GPL");
 668
 669 MODULE_AUTHOR(DRIVER_AUTHOR);
 670 MODULE_DESCRIPTION(DRIVER_DESC);
 671
 672 /*
 673  * The following describes what I learned from studying the old
 674  * ark3116.c driver, disassembling the windows driver, and some lucky
 675  * guesses. Since I do not have any datasheet or other
 676  * documentation, inaccuracies are almost guaranteed.
 677  *
 678  * Some specs for the ARK3116 can be found here:
 679  * http://web.archive.org/web/20060318000438/
 680  *   www.arkmicro.com/en/products/view.php?id=10
 681  * On that page, 2 GPIO pins are mentioned: I assume these are the
 682  * OUT1 and OUT2 pins of the UART, so I added support for those
 683  * through the MCR. Since the pins are not available on my hardware,
 684  * I could not verify this.
 685  * Also, it states there is "on-chip hardware flow control". I have
 686  * discovered how to enable that. Unfortunately, I do not know how to
 687  * enable XON/XOFF (software) flow control, which would need support
 688  * from the chip as well to work. Because of the wording on the web
 689  * page there is a real possibility the chip simply does not support
 690  * software flow control.
 691  *
 692  * I got my ark3116 as part of a mobile phone adapter cable. On the
 693  * PCB, the following numbered contacts are present:
 694  *
 695  *  1:- +5V
 696  *  2:o DTR
 697  *  3:i RX
 698  *  4:i DCD
 699  *  5:o RTS
 700  *  6:o TX
 701  *  7:i RI
 702  *  8:i DSR
 703  * 10:- 0V
 704  * 11:i CTS
 705  *
 706  * On my chip, all signals seem to be 3.3V, but 5V tolerant. But that
 707  * may be different for the one you have ;-).
 708  *
 709  * The windows driver limits the registers to 0-F, so I assume there
 710  * are actually 16 present on the device.
 711  *
 712  * On an UART interrupt, 4 bytes of data come in on the interrupt
 713  * endpoint. The bytes are 0xe8 IIR LSR MSR.
 714  *
 715  * The baudrate seems to be generated from the 12MHz crystal, using
 716  * 4-times subsampling. So quot=12e6/(4*baud). Also see description
 717  * of register E.
 718  *
 719  * Registers 0-7:
 720  * These seem to be the same as for a regular 16450. The FCR is set
 721  * to UART_FCR_DMA_SELECT (0x8), I guess to enable transfers between
 722  * the UART and the USB bridge/DMA engine.
 723  *
 724  * Register 8:
 725  * By trial and error, I found out that bit 0 enables hardware CTS,
 726  * stopping TX when CTS is +5V. Bit 1 does the same for RTS, making
 727  * RTS +5V when the 3116 cannot transfer the data to the USB bus
 728  * (verified by disabling the reading URB). Note that as far as I can
 729  * tell, the windows driver does NOT use this, so there might be some
 730  * hardware bug or something.
 731  *
 732  * According to a patch provided here
 733  * (http://lkml.org/lkml/2009/7/26/56), the ARK3116 can also be used
 734  * as an IrDA dongle. Since I do not have such a thing, I could not
 735  * investigate that aspect. However, I can speculate ;-).
 736  *
 737  * - IrDA encodes data differently than RS232. Most likely, one of
 738  *   the bits in registers 9..E enables the IR ENDEC (encoder/decoder).
 739  * - Depending on the IR transceiver, the input and output need to be
 740  *   inverted, so there are probably bits for that as well.
 741  * - IrDA is half-duplex, so there should be a bit for selecting that.
 742  *
 743  * This still leaves at least two registers unaccounted for. Perhaps
 744  * The chip can do XON/XOFF or CRC in HW?
 745  *
 746  * Register 9:
 747  * Set to 0x00 for IrDA, when the baudrate is initialised.
 748  *
 749  * Register A:
 750  * Set to 0x01 for IrDA, at init.
 751  *
 752  * Register B:
 753  * Set to 0x01 for IrDA, 0x00 for RS232, at init.
 754  *
 755  * Register C:
 756  * Set to 00 for IrDA, at init.
 757  *
 758  * Register D:
 759  * Set to 0x41 for IrDA, at init.
 760  *
 761  * Register E:
 762  * Somekind of baudrate override. The windows driver seems to set
 763  * this to 0x00 for normal baudrates, 0x01 for 460800, 0x02 for 921600.
 764  * Since 460800 and 921600 cannot be obtained by dividing 3MHz by an integer,
 765  * it could be somekind of subdivisor thingy.
 766  * However,it does not seem to do anything: selecting 921600 (divisor 3,
 767  * reg E=2), still gets 1 MHz. I also checked if registers 9, C or F would
 768  * work, but they don't.
 769  *
 770  * Register F: unknown
 771  */