drivers/usb/serial/ark3116.c

   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 (1*HZ)
  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->serial->minor;
 417                 serstruct.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  */