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