drivers/usb/serial/oti6858.c

   1 /*
   2  * Ours Technology Inc. OTi-6858 USB to serial adapter driver.
   3  *
   4  * Copyleft  (C) 2007 Kees Lemmens (adapted for kernel 2.6.20)
   5  * Copyright (C) 2006 Tomasz Michal Lukaszewski (FIXME: add e-mail)
   6  * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
   7  * Copyright (C) 2003 IBM Corp.
   8  *
   9  * Many thanks to the authors of pl2303 driver: all functions in this file
  10  * are heavily based on pl2303 code, buffering code is a 1-to-1 copy.
  11  *
  12  * Warning! You use this driver on your own risk! The only official
  13  * description of this device I have is datasheet from manufacturer,
  14  * and it doesn't contain almost any information needed to write a driver.
  15  * Almost all knowlegde used while writing this driver was gathered by:
  16  *  - analyzing traffic between device and the M$ Windows 2000 driver,
  17  *  - trying different bit combinations and checking pin states
  18  *    with a voltmeter,
  19  *  - receiving malformed frames and producing buffer overflows
  20  *    to learn how errors are reported,
  21  * So, THIS CODE CAN DESTROY OTi-6858 AND ANY OTHER DEVICES, THAT ARE
  22  * CONNECTED TO IT!
  23  *
  24  * This program is free software; you can redistribute it and/or modify
  25  * it under the terms of the GNU General Public License as published by
  26  * the Free Software Foundation; either version 2 of the License.
  27  *
  28  * See Documentation/usb/usb-serial.txt for more information on using this driver
  29  *
  30  * TODO:
  31  *  - implement correct flushing for ioctls and oti6858_close()
  32  *  - check how errors (rx overflow, parity error, framing error) are reported
  33  *  - implement oti6858_break_ctl()
  34  *  - implement more ioctls
  35  *  - test/implement flow control
  36  *  - allow setting custom baud rates
  37  */
  38
  39 #include <linux/kernel.h>
  40 #include <linux/errno.h>
  41 #include <linux/init.h>
  42 #include <linux/slab.h>
  43 #include <linux/tty.h>
  44 #include <linux/tty_driver.h>
  45 #include <linux/tty_flip.h>
  46 #include <linux/serial.h>
  47 #include <linux/module.h>
  48 #include <linux/moduleparam.h>
  49 #include <linux/spinlock.h>
  50 #include <linux/usb.h>
  51 #include <linux/usb/serial.h>
  52 #include <asm/uaccess.h>
  53 #include "oti6858.h"
  54
  55 #define OTI6858_DESCRIPTION \
  56         "Ours Technology Inc. OTi-6858 USB to serial adapter driver"
  57 #define OTI6858_AUTHOR "Tomasz Michal Lukaszewski <FIXME@FIXME>"
  58 #define OTI6858_VERSION "0.1"
  59
  60 static struct usb_device_id id_table [] = {
  61         { USB_DEVICE(OTI6858_VENDOR_ID, OTI6858_PRODUCT_ID) },
  62         { }
  63 };
  64
  65 MODULE_DEVICE_TABLE(usb, id_table);
  66
  67 static struct usb_driver oti6858_driver = {
  68         .name =         "oti6858",
  69         .probe =        usb_serial_probe,
  70         .disconnect =   usb_serial_disconnect,
  71         .id_table =     id_table,
  72         .no_dynamic_id =        1,
  73 };
  74
  75 static int debug;
  76
  77
  78 /* buffering code, copied from pl2303 driver */
  79 #define PL2303_BUF_SIZE         1024
  80 #define PL2303_TMP_BUF_SIZE     1024
  81
  82 struct oti6858_buf {
  83         unsigned int    buf_size;
  84         char            *buf_buf;
  85         char            *buf_get;
  86         char            *buf_put;
  87 };
  88
  89 /* requests */
  90 #define OTI6858_REQ_GET_STATUS          (USB_DIR_IN | USB_TYPE_VENDOR | 0x00)
  91 #define OTI6858_REQ_T_GET_STATUS        0x01
  92
  93 #define OTI6858_REQ_SET_LINE            (USB_DIR_OUT | USB_TYPE_VENDOR | 0x00)
  94 #define OTI6858_REQ_T_SET_LINE          0x00
  95
  96 #define OTI6858_REQ_CHECK_TXBUFF        (USB_DIR_IN | USB_TYPE_VENDOR | 0x01)
  97 #define OTI6858_REQ_T_CHECK_TXBUFF      0x00
  98
  99 /* format of the control packet */
 100 struct oti6858_control_pkt {
 101         __le16  divisor;        /* baud rate = 96000000 / (16 * divisor), LE */
 102 #define OTI6858_MAX_BAUD_RATE   3000000
 103         u8      frame_fmt;
 104 #define FMT_STOP_BITS_MASK      0xc0
 105 #define FMT_STOP_BITS_1         0x00
 106 #define FMT_STOP_BITS_2         0x40    /* 1.5 stop bits if FMT_DATA_BITS_5 */
 107 #define FMT_PARITY_MASK         0x38
 108 #define FMT_PARITY_NONE         0x00
 109 #define FMT_PARITY_ODD          0x08
 110 #define FMT_PARITY_EVEN         0x18
 111 #define FMT_PARITY_MARK         0x28
 112 #define FMT_PARITY_SPACE        0x38
 113 #define FMT_DATA_BITS_MASK      0x03
 114 #define FMT_DATA_BITS_5         0x00
 115 #define FMT_DATA_BITS_6         0x01
 116 #define FMT_DATA_BITS_7         0x02
 117 #define FMT_DATA_BITS_8         0x03
 118         u8      something;      /* always equals 0x43 */
 119         u8      control;        /* settings of flow control lines */
 120 #define CONTROL_MASK            0x0c
 121 #define CONTROL_DTR_HIGH        0x08
 122 #define CONTROL_RTS_HIGH        0x04
 123         u8      tx_status;
 124 #define TX_BUFFER_EMPTIED       0x09
 125         u8      pin_state;
 126 #define PIN_MASK                0x3f
 127 #define PIN_RTS                 0x20    /* output pin */
 128 #define PIN_CTS                 0x10    /* input pin, active low */
 129 #define PIN_DSR                 0x08    /* input pin, active low */
 130 #define PIN_DTR                 0x04    /* output pin */
 131 #define PIN_RI                  0x02    /* input pin, active low */
 132 #define PIN_DCD                 0x01    /* input pin, active low */
 133         u8      rx_bytes_avail;         /* number of bytes in rx buffer */;
 134 };
 135
 136 #define OTI6858_CTRL_PKT_SIZE   sizeof(struct oti6858_control_pkt)
 137 #define OTI6858_CTRL_EQUALS_PENDING(a, priv) \
 138         (    ((a)->divisor == (priv)->pending_setup.divisor) \
 139           && ((a)->control == (priv)->pending_setup.control) \
 140           && ((a)->frame_fmt == (priv)->pending_setup.frame_fmt) )
 141
 142 /* function prototypes */
 143 static int oti6858_open(struct usb_serial_port *port, struct file *filp);
 144 static void oti6858_close(struct usb_serial_port *port, struct file *filp);
 145 static void oti6858_set_termios(struct usb_serial_port *port,
 146                                 struct ktermios *old);
 147 static int oti6858_ioctl(struct usb_serial_port *port, struct file *file,
 148                         unsigned int cmd, unsigned long arg);
 149 static void oti6858_read_int_callback(struct urb *urb);
 150 static void oti6858_read_bulk_callback(struct urb *urb);
 151 static void oti6858_write_bulk_callback(struct urb *urb);
 152 static int oti6858_write(struct usb_serial_port *port,
 153                         const unsigned char *buf, int count);
 154 static int oti6858_write_room(struct usb_serial_port *port);
 155 static void oti6858_break_ctl(struct usb_serial_port *port, int break_state);
 156 static int oti6858_chars_in_buffer(struct usb_serial_port *port);
 157 static int oti6858_tiocmget(struct usb_serial_port *port, struct file *file);
 158 static int oti6858_tiocmset(struct usb_serial_port *port, struct file *file,
 159                                 unsigned int set, unsigned int clear);
 160 static int oti6858_startup(struct usb_serial *serial);
 161 static void oti6858_shutdown(struct usb_serial *serial);
 162
 163 /* functions operating on buffers */
 164 static struct oti6858_buf *oti6858_buf_alloc(unsigned int size);
 165 static void oti6858_buf_free(struct oti6858_buf *pb);
 166 static void oti6858_buf_clear(struct oti6858_buf *pb);
 167 static unsigned int oti6858_buf_data_avail(struct oti6858_buf *pb);
 168 static unsigned int oti6858_buf_space_avail(struct oti6858_buf *pb);
 169 static unsigned int oti6858_buf_put(struct oti6858_buf *pb, const char *buf,
 170                                         unsigned int count);
 171 static unsigned int oti6858_buf_get(struct oti6858_buf *pb, char *buf,
 172                                         unsigned int count);
 173
 174
 175 /* device info */
 176 static struct usb_serial_driver oti6858_device = {
 177         .driver = {
 178                 .owner =        THIS_MODULE,
 179                 .name =         "oti6858",
 180         },
 181         .id_table =             id_table,
 182         .num_ports =            1,
 183         .open =                 oti6858_open,
 184         .close =                oti6858_close,
 185         .write =                oti6858_write,
 186         .ioctl =                oti6858_ioctl,
 187         .break_ctl =            oti6858_break_ctl,
 188         .set_termios =          oti6858_set_termios,
 189         .tiocmget =             oti6858_tiocmget,
 190         .tiocmset =             oti6858_tiocmset,
 191         .read_bulk_callback =   oti6858_read_bulk_callback,
 192         .read_int_callback =    oti6858_read_int_callback,
 193         .write_bulk_callback =  oti6858_write_bulk_callback,
 194         .write_room =           oti6858_write_room,
 195         .chars_in_buffer =      oti6858_chars_in_buffer,
 196         .attach =               oti6858_startup,
 197         .shutdown =             oti6858_shutdown,
 198 };
 199
 200 struct oti6858_private {
 201         spinlock_t lock;
 202
 203         struct oti6858_buf *buf;
 204         struct oti6858_control_pkt status;
 205
 206         struct {
 207                 u8 read_urb_in_use;
 208                 u8 write_urb_in_use;
 209                 u8 termios_initialized;
 210         } flags;
 211         struct delayed_work delayed_write_work;
 212
 213         struct {
 214                 __le16 divisor;
 215                 u8 frame_fmt;
 216                 u8 control;
 217         } pending_setup;
 218         u8 transient;
 219         u8 setup_done;
 220         struct delayed_work delayed_setup_work;
 221
 222         wait_queue_head_t intr_wait;
 223         struct usb_serial_port *port;   /* USB port with which associated */
 224 };
 225
 226 #undef dbg
 227 /* #define dbg(format, arg...) printk(KERN_INFO "%s: " format "\n", __FILE__, ## arg) */
 228 #define dbg(format, arg...) printk(KERN_INFO "" format "\n", ## arg)
 229
 230 static void setup_line(struct work_struct *work)
 231 {
 232         struct oti6858_private *priv = container_of(work, struct oti6858_private, delayed_setup_work.work);
 233         struct usb_serial_port *port = priv->port;
 234         struct oti6858_control_pkt *new_setup;
 235         unsigned long flags;
 236         int result;
 237
 238         dbg("%s(port = %d)", __func__, port->number);
 239
 240         if ((new_setup = kmalloc(OTI6858_CTRL_PKT_SIZE, GFP_KERNEL)) == NULL) {
 241                 dev_err(&port->dev, "%s(): out of memory!\n", __func__);
 242                 /* we will try again */
 243                 schedule_delayed_work(&priv->delayed_setup_work, msecs_to_jiffies(2));
 244                 return;
 245         }
 246
 247         result = usb_control_msg(port->serial->dev,
 248                                 usb_rcvctrlpipe(port->serial->dev, 0),
 249                                 OTI6858_REQ_T_GET_STATUS,
 250                                 OTI6858_REQ_GET_STATUS,
 251                                 0, 0,
 252                                 new_setup, OTI6858_CTRL_PKT_SIZE,
 253                                 100);
 254
 255         if (result != OTI6858_CTRL_PKT_SIZE) {
 256                 dev_err(&port->dev, "%s(): error reading status\n", __func__);
 257                 kfree(new_setup);
 258                 /* we will try again */
 259                 schedule_delayed_work(&priv->delayed_setup_work, msecs_to_jiffies(2));
 260                 return;
 261         }
 262
 263         spin_lock_irqsave(&priv->lock, flags);
 264         if (!OTI6858_CTRL_EQUALS_PENDING(new_setup, priv)) {
 265                 new_setup->divisor = priv->pending_setup.divisor;
 266                 new_setup->control = priv->pending_setup.control;
 267                 new_setup->frame_fmt = priv->pending_setup.frame_fmt;
 268
 269                 spin_unlock_irqrestore(&priv->lock, flags);
 270                 result = usb_control_msg(port->serial->dev,
 271                                         usb_sndctrlpipe(port->serial->dev, 0),
 272                                         OTI6858_REQ_T_SET_LINE,
 273                                         OTI6858_REQ_SET_LINE,
 274                                         0, 0,
 275                                         new_setup, OTI6858_CTRL_PKT_SIZE,
 276                                         100);
 277         } else {
 278                 spin_unlock_irqrestore(&priv->lock, flags);
 279                 result = 0;
 280         }
 281         kfree(new_setup);
 282
 283         spin_lock_irqsave(&priv->lock, flags);
 284         if (result != OTI6858_CTRL_PKT_SIZE)
 285                 priv->transient = 0;
 286         priv->setup_done = 1;
 287         spin_unlock_irqrestore(&priv->lock, flags);
 288
 289         dbg("%s(): submitting interrupt urb", __func__);
 290         port->interrupt_in_urb->dev = port->serial->dev;
 291         result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
 292         if (result != 0) {
 293                 dev_err(&port->dev, "%s(): usb_submit_urb() failed"
 294                                 " with error %d\n", __func__, result);
 295         }
 296 }
 297
 298 void send_data(struct work_struct *work)
 299 {
 300         struct oti6858_private *priv = container_of(work, struct oti6858_private, delayed_write_work.work);
 301         struct usb_serial_port *port = priv->port;
 302         int count = 0, result;
 303         unsigned long flags;
 304         unsigned char allow;
 305
 306         dbg("%s(port = %d)", __func__, port->number);
 307
 308         spin_lock_irqsave(&priv->lock, flags);
 309         if (priv->flags.write_urb_in_use) {
 310                 spin_unlock_irqrestore(&priv->lock, flags);
 311                 schedule_delayed_work(&priv->delayed_write_work, msecs_to_jiffies(2));
 312                 return;
 313         }
 314         priv->flags.write_urb_in_use = 1;
 315
 316         count = oti6858_buf_data_avail(priv->buf);
 317         spin_unlock_irqrestore(&priv->lock, flags);
 318         if (count > port->bulk_out_size)
 319                 count = port->bulk_out_size;
 320
 321         if (count != 0) {
 322                 result = usb_control_msg(port->serial->dev,
 323                                 usb_rcvctrlpipe(port->serial->dev, 0),
 324                                 OTI6858_REQ_T_CHECK_TXBUFF,
 325                                 OTI6858_REQ_CHECK_TXBUFF,
 326                                 count, 0, &allow, 1, 100);
 327                 if (result != 1 || allow != 0)
 328                         count = 0;
 329         }
 330
 331         if (count == 0) {
 332                 priv->flags.write_urb_in_use = 0;
 333
 334                 dbg("%s(): submitting interrupt urb", __func__);
 335                 port->interrupt_in_urb->dev = port->serial->dev;
 336                 result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
 337                 if (result != 0) {
 338                         dev_err(&port->dev, "%s(): usb_submit_urb() failed"
 339                                 " with error %d\n", __func__, result);
 340                 }
 341                 return;
 342         }
 343
 344         spin_lock_irqsave(&priv->lock, flags);
 345         oti6858_buf_get(priv->buf, port->write_urb->transfer_buffer, count);
 346         spin_unlock_irqrestore(&priv->lock, flags);
 347
 348         port->write_urb->transfer_buffer_length = count;
 349         port->write_urb->dev = port->serial->dev;
 350         result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
 351         if (result != 0) {
 352                 dev_err(&port->dev, "%s(): usb_submit_urb() failed"
 353                                " with error %d\n", __func__, result);
 354                 priv->flags.write_urb_in_use = 0;
 355         }
 356
 357         usb_serial_port_softint(port);
 358 }
 359
 360 static int oti6858_startup(struct usb_serial *serial)
 361 {
 362         struct usb_serial_port *port = serial->port[0];
 363         struct oti6858_private *priv;
 364         int i;
 365
 366         for (i = 0; i < serial->num_ports; ++i) {
 367                 priv = kzalloc(sizeof(struct oti6858_private), GFP_KERNEL);
 368                 if (!priv)
 369                         break;
 370                 priv->buf = oti6858_buf_alloc(PL2303_BUF_SIZE);
 371                 if (priv->buf == NULL) {
 372                         kfree(priv);
 373                         break;
 374                 }
 375
 376                 spin_lock_init(&priv->lock);
 377                 init_waitqueue_head(&priv->intr_wait);
 378 //              INIT_WORK(&priv->setup_work, setup_line, serial->port[i]);
 379 //              INIT_WORK(&priv->write_work, send_data, serial->port[i]);
 380                 priv->port = port;
 381                 INIT_DELAYED_WORK(&priv->delayed_setup_work, setup_line);
 382                 INIT_DELAYED_WORK(&priv->delayed_write_work, send_data);
 383
 384                 usb_set_serial_port_data(serial->port[i], priv);
 385         }
 386         if (i == serial->num_ports)
 387                 return 0;
 388
 389         for (--i; i >= 0; --i) {
 390                 priv = usb_get_serial_port_data(serial->port[i]);
 391                 oti6858_buf_free(priv->buf);
 392                 kfree(priv);
 393                 usb_set_serial_port_data(serial->port[i], NULL);
 394         }
 395         return -ENOMEM;
 396 }
 397
 398 static int oti6858_write(struct usb_serial_port *port,
 399                         const unsigned char *buf, int count)
 400 {
 401         struct oti6858_private *priv = usb_get_serial_port_data(port);
 402         unsigned long flags;
 403
 404         dbg("%s(port = %d, count = %d)", __func__, port->number, count);
 405
 406         if (!count)
 407                 return count;
 408
 409         spin_lock_irqsave(&priv->lock, flags);
 410         count = oti6858_buf_put(priv->buf, buf, count);
 411         spin_unlock_irqrestore(&priv->lock, flags);
 412
 413         return count;
 414 }
 415
 416 static int oti6858_write_room(struct usb_serial_port *port)
 417 {
 418         struct oti6858_private *priv = usb_get_serial_port_data(port);
 419         int room = 0;
 420         unsigned long flags;
 421
 422         dbg("%s(port = %d)", __func__, port->number);
 423
 424         spin_lock_irqsave(&priv->lock, flags);
 425         room = oti6858_buf_space_avail(priv->buf);
 426         spin_unlock_irqrestore(&priv->lock, flags);
 427
 428         return room;
 429 }
 430
 431 static int oti6858_chars_in_buffer(struct usb_serial_port *port)
 432 {
 433         struct oti6858_private *priv = usb_get_serial_port_data(port);
 434         int chars = 0;
 435         unsigned long flags;
 436
 437         dbg("%s(port = %d)", __func__, port->number);
 438
 439         spin_lock_irqsave(&priv->lock, flags);
 440         chars = oti6858_buf_data_avail(priv->buf);
 441         spin_unlock_irqrestore(&priv->lock, flags);
 442
 443         return chars;
 444 }
 445
 446 static void oti6858_set_termios(struct usb_serial_port *port,
 447                                 struct ktermios *old_termios)
 448 {
 449         struct oti6858_private *priv = usb_get_serial_port_data(port);
 450         unsigned long flags;
 451         unsigned int cflag;
 452         u8 frame_fmt, control;
 453         __le16 divisor;
 454         int br;
 455
 456         dbg("%s(port = %d)", __func__, port->number);
 457
 458         if (!port->tty || !port->tty->termios) {
 459                 dbg("%s(): no tty structures", __func__);
 460                 return;
 461         }
 462
 463         spin_lock_irqsave(&priv->lock, flags);
 464         if (!priv->flags.termios_initialized) {
 465                 *(port->tty->termios) = tty_std_termios;
 466                 port->tty->termios->c_cflag = B38400 | CS8 | CREAD | HUPCL | CLOCAL;
 467                 priv->flags.termios_initialized = 1;
 468                 port->tty->termios->c_ispeed = 38400;
 469                 port->tty->termios->c_ospeed = 38400;
 470         }
 471         spin_unlock_irqrestore(&priv->lock, flags);
 472
 473         cflag = port->tty->termios->c_cflag;
 474
 475         spin_lock_irqsave(&priv->lock, flags);
 476         divisor = priv->pending_setup.divisor;
 477         frame_fmt = priv->pending_setup.frame_fmt;
 478         control = priv->pending_setup.control;
 479         spin_unlock_irqrestore(&priv->lock, flags);
 480
 481         frame_fmt &= ~FMT_DATA_BITS_MASK;
 482         switch (cflag & CSIZE) {
 483                 case CS5:
 484                         frame_fmt |= FMT_DATA_BITS_5;
 485                         break;
 486                 case CS6:
 487                         frame_fmt |= FMT_DATA_BITS_6;
 488                         break;
 489                 case CS7:
 490                         frame_fmt |= FMT_DATA_BITS_7;
 491                         break;
 492                 default:
 493                 case CS8:
 494                         frame_fmt |= FMT_DATA_BITS_8;
 495                         break;
 496         }
 497
 498         /* manufacturer claims that this device can work with baud rates
 499          * up to 3 Mbps; I've tested it only on 115200 bps, so I can't
 500          * guarantee that any other baud rate will work (especially
 501          * the higher ones)
 502          */
 503         br = tty_get_baud_rate(port->tty);
 504         if (br == 0) {
 505                 divisor = 0;
 506         } else {
 507                 int real_br;
 508                 int new_divisor;
 509                 br = min(br, OTI6858_MAX_BAUD_RATE);
 510
 511                 new_divisor = (96000000 + 8 * br) / (16 * br);
 512                 real_br = 96000000 / (16 * new_divisor);
 513                 divisor = cpu_to_le16(new_divisor);
 514                 tty_encode_baud_rate(port->tty, real_br, real_br);
 515         }
 516
 517         frame_fmt &= ~FMT_STOP_BITS_MASK;
 518         if ((cflag & CSTOPB) != 0) {
 519                 frame_fmt |= FMT_STOP_BITS_2;
 520         } else {
 521                 frame_fmt |= FMT_STOP_BITS_1;
 522         }
 523
 524         frame_fmt &= ~FMT_PARITY_MASK;
 525         if ((cflag & PARENB) != 0) {
 526                 if ((cflag & PARODD) != 0) {
 527                         frame_fmt |= FMT_PARITY_ODD;
 528                 } else {
 529                         frame_fmt |= FMT_PARITY_EVEN;
 530                 }
 531         } else {
 532                 frame_fmt |= FMT_PARITY_NONE;
 533         }
 534
 535         control &= ~CONTROL_MASK;
 536         if ((cflag & CRTSCTS) != 0)
 537                 control |= (CONTROL_DTR_HIGH | CONTROL_RTS_HIGH);
 538
 539         /* change control lines if we are switching to or from B0 */
 540         /* FIXME:
 541         spin_lock_irqsave(&priv->lock, flags);
 542         control = priv->line_control;
 543         if ((cflag & CBAUD) == B0)
 544                 priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
 545         else
 546                 priv->line_control |= (CONTROL_DTR | CONTROL_RTS);
 547         if (control != priv->line_control) {
 548                 control = priv->line_control;
 549                 spin_unlock_irqrestore(&priv->lock, flags);
 550                 set_control_lines(serial->dev, control);
 551         } else {
 552                 spin_unlock_irqrestore(&priv->lock, flags);
 553         }
 554         */
 555
 556         spin_lock_irqsave(&priv->lock, flags);
 557         if (divisor != priv->pending_setup.divisor
 558                         || control != priv->pending_setup.control
 559                         || frame_fmt != priv->pending_setup.frame_fmt) {
 560                 priv->pending_setup.divisor = divisor;
 561                 priv->pending_setup.control = control;
 562                 priv->pending_setup.frame_fmt = frame_fmt;
 563         }
 564         spin_unlock_irqrestore(&priv->lock, flags);
 565 }
 566
 567 static int oti6858_open(struct usb_serial_port *port, struct file *filp)
 568 {
 569         struct oti6858_private *priv = usb_get_serial_port_data(port);
 570         struct ktermios tmp_termios;
 571         struct usb_serial *serial = port->serial;
 572         struct oti6858_control_pkt *buf;
 573         unsigned long flags;
 574         int result;
 575
 576         dbg("%s(port = %d)", __func__, port->number);
 577
 578         usb_clear_halt(serial->dev, port->write_urb->pipe);
 579         usb_clear_halt(serial->dev, port->read_urb->pipe);
 580
 581         if (port->open_count != 1)
 582                 return 0;
 583
 584         if ((buf = kmalloc(OTI6858_CTRL_PKT_SIZE, GFP_KERNEL)) == NULL) {
 585                 dev_err(&port->dev, "%s(): out of memory!\n", __func__);
 586                 return -ENOMEM;
 587         }
 588
 589         result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
 590                                 OTI6858_REQ_T_GET_STATUS,
 591                                 OTI6858_REQ_GET_STATUS,
 592                                 0, 0,
 593                                 buf, OTI6858_CTRL_PKT_SIZE,
 594                                 100);
 595         if (result != OTI6858_CTRL_PKT_SIZE) {
 596                 /* assume default (after power-on reset) values */
 597                 buf->divisor = cpu_to_le16(0x009c);     /* 38400 bps */
 598                 buf->frame_fmt = 0x03;  /* 8N1 */
 599                 buf->something = 0x43;
 600                 buf->control = 0x4c;    /* DTR, RTS */
 601                 buf->tx_status = 0x00;
 602                 buf->pin_state = 0x5b;  /* RTS, CTS, DSR, DTR, RI, DCD */
 603                 buf->rx_bytes_avail = 0x00;
 604         }
 605
 606         spin_lock_irqsave(&priv->lock, flags);
 607         memcpy(&priv->status, buf, OTI6858_CTRL_PKT_SIZE);
 608         priv->pending_setup.divisor = buf->divisor;
 609         priv->pending_setup.frame_fmt = buf->frame_fmt;
 610         priv->pending_setup.control = buf->control;
 611         spin_unlock_irqrestore(&priv->lock, flags);
 612         kfree(buf);
 613
 614         dbg("%s(): submitting interrupt urb", __func__);
 615         port->interrupt_in_urb->dev = serial->dev;
 616         result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 617         if (result != 0) {
 618                 dev_err(&port->dev, "%s(): usb_submit_urb() failed"
 619                                " with error %d\n", __func__, result);
 620                 oti6858_close(port, NULL);
 621                 return -EPROTO;
 622         }
 623
 624         /* setup termios */
 625         if (port->tty)
 626                 oti6858_set_termios(port, &tmp_termios);
 627
 628         return 0;
 629 }
 630
 631 static void oti6858_close(struct usb_serial_port *port, struct file *filp)
 632 {
 633         struct oti6858_private *priv = usb_get_serial_port_data(port);
 634         unsigned long flags;
 635         long timeout;
 636         wait_queue_t wait;
 637
 638         dbg("%s(port = %d)", __func__, port->number);
 639
 640         /* wait for data to drain from the buffer */
 641         spin_lock_irqsave(&priv->lock, flags);
 642         timeout = 30 * HZ;      /* PL2303_CLOSING_WAIT */
 643         init_waitqueue_entry(&wait, current);
 644         add_wait_queue(&port->tty->write_wait, &wait);
 645         dbg("%s(): entering wait loop", __func__);
 646         for (;;) {
 647                 set_current_state(TASK_INTERRUPTIBLE);
 648                 if (oti6858_buf_data_avail(priv->buf) == 0
 649                 || timeout == 0 || signal_pending(current)
 650                 || port->serial->disconnected)
 651                         break;
 652                 spin_unlock_irqrestore(&priv->lock, flags);
 653                 timeout = schedule_timeout(timeout);
 654                 spin_lock_irqsave(&priv->lock, flags);
 655         }
 656         set_current_state(TASK_RUNNING);
 657         remove_wait_queue(&port->tty->write_wait, &wait);
 658         dbg("%s(): after wait loop", __func__);
 659
 660         /* clear out any remaining data in the buffer */
 661         oti6858_buf_clear(priv->buf);
 662         spin_unlock_irqrestore(&priv->lock, flags);
 663
 664         /* wait for characters to drain from the device */
 665         /* (this is long enough for the entire 256 byte */
 666         /* pl2303 hardware buffer to drain with no flow */
 667         /* control for data rates of 1200 bps or more, */
 668         /* for lower rates we should really know how much */
 669         /* data is in the buffer to compute a delay */
 670         /* that is not unnecessarily long) */
 671         /* FIXME
 672         bps = tty_get_baud_rate(port->tty);
 673         if (bps > 1200)
 674                 timeout = max((HZ*2560)/bps,HZ/10);
 675         else
 676         */
 677                 timeout = 2*HZ;
 678         schedule_timeout_interruptible(timeout);
 679         dbg("%s(): after schedule_timeout_interruptible()", __func__);
 680
 681         /* cancel scheduled setup */
 682         cancel_delayed_work(&priv->delayed_setup_work);
 683         cancel_delayed_work(&priv->delayed_write_work);
 684         flush_scheduled_work();
 685
 686         /* shutdown our urbs */
 687         dbg("%s(): shutting down urbs", __func__);
 688         usb_kill_urb(port->write_urb);
 689         usb_kill_urb(port->read_urb);
 690         usb_kill_urb(port->interrupt_in_urb);
 691
 692         /*
 693         if (port->tty && (port->tty->termios->c_cflag) & HUPCL) {
 694                 // drop DTR and RTS
 695                 spin_lock_irqsave(&priv->lock, flags);
 696                 priv->pending_setup.control &= ~CONTROL_MASK;
 697                 spin_unlock_irqrestore(&priv->lock, flags);
 698         }
 699         */
 700 }
 701
 702 static int oti6858_tiocmset(struct usb_serial_port *port, struct file *file,
 703                                 unsigned int set, unsigned int clear)
 704 {
 705         struct oti6858_private *priv = usb_get_serial_port_data(port);
 706         unsigned long flags;
 707         u8 control;
 708
 709         dbg("%s(port = %d, set = 0x%08x, clear = 0x%08x)",
 710                                 __func__, port->number, set, clear);
 711
 712         if (!usb_get_intfdata(port->serial->interface))
 713                 return -ENODEV;
 714
 715         /* FIXME: check if this is correct (active high/low) */
 716         spin_lock_irqsave(&priv->lock, flags);
 717         control = priv->pending_setup.control;
 718         if ((set & TIOCM_RTS) != 0)
 719                 control |= CONTROL_RTS_HIGH;
 720         if ((set & TIOCM_DTR) != 0)
 721                 control |= CONTROL_DTR_HIGH;
 722         if ((clear & TIOCM_RTS) != 0)
 723                 control &= ~CONTROL_RTS_HIGH;
 724         if ((clear & TIOCM_DTR) != 0)
 725                 control &= ~CONTROL_DTR_HIGH;
 726
 727         if (control != priv->pending_setup.control) {
 728                 priv->pending_setup.control = control;
 729         }
 730         spin_unlock_irqrestore(&priv->lock, flags);
 731
 732         return 0;
 733 }
 734
 735 static int oti6858_tiocmget(struct usb_serial_port *port, struct file *file)
 736 {
 737         struct oti6858_private *priv = usb_get_serial_port_data(port);
 738         unsigned long flags;
 739         unsigned pin_state;
 740         unsigned result = 0;
 741
 742         dbg("%s(port = %d)", __func__, port->number);
 743
 744         if (!usb_get_intfdata(port->serial->interface))
 745                 return -ENODEV;
 746
 747         spin_lock_irqsave(&priv->lock, flags);
 748         pin_state = priv->status.pin_state & PIN_MASK;
 749         spin_unlock_irqrestore(&priv->lock, flags);
 750
 751         /* FIXME: check if this is correct (active high/low) */
 752         if ((pin_state & PIN_RTS) != 0)
 753                 result |= TIOCM_RTS;
 754         if ((pin_state & PIN_CTS) != 0)
 755                 result |= TIOCM_CTS;
 756         if ((pin_state & PIN_DSR) != 0)
 757                 result |= TIOCM_DSR;
 758         if ((pin_state & PIN_DTR) != 0)
 759                 result |= TIOCM_DTR;
 760         if ((pin_state & PIN_RI) != 0)
 761                 result |= TIOCM_RI;
 762         if ((pin_state & PIN_DCD) != 0)
 763                 result |= TIOCM_CD;
 764
 765         dbg("%s() = 0x%08x", __func__, result);
 766
 767         return result;
 768 }
 769
 770 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 771 {
 772         struct oti6858_private *priv = usb_get_serial_port_data(port);
 773         unsigned long flags;
 774         unsigned int prev, status;
 775         unsigned int changed;
 776
 777         spin_lock_irqsave(&priv->lock, flags);
 778         prev = priv->status.pin_state;
 779         spin_unlock_irqrestore(&priv->lock, flags);
 780
 781         while (1) {
 782                 wait_event_interruptible(priv->intr_wait, priv->status.pin_state != prev);
 783                 if (signal_pending(current))
 784                         return -ERESTARTSYS;
 785
 786                 spin_lock_irqsave(&priv->lock, flags);
 787                 status = priv->status.pin_state & PIN_MASK;
 788                 spin_unlock_irqrestore(&priv->lock, flags);
 789
 790                 changed = prev ^ status;
 791                 /* FIXME: check if this is correct (active high/low) */
 792                 if (    ((arg & TIOCM_RNG) && (changed & PIN_RI)) ||
 793                         ((arg & TIOCM_DSR) && (changed & PIN_DSR)) ||
 794                         ((arg & TIOCM_CD)  && (changed & PIN_DCD)) ||
 795                         ((arg & TIOCM_CTS) && (changed & PIN_CTS))) {
 796                                 return 0;
 797                 }
 798                 prev = status;
 799         }
 800
 801         /* NOTREACHED */
 802         return 0;
 803 }
 804
 805 static int oti6858_ioctl(struct usb_serial_port *port, struct file *file,
 806                         unsigned int cmd, unsigned long arg)
 807 {
 808         void __user *user_arg = (void __user *) arg;
 809         unsigned int x;
 810
 811         dbg("%s(port = %d, cmd = 0x%04x, arg = 0x%08lx)",
 812                                 __func__, port->number, cmd, arg);
 813
 814         switch (cmd) {
 815                 case TIOCMBIS:
 816                         if (copy_from_user(&x, user_arg, sizeof(x)))
 817                                 return -EFAULT;
 818                         return oti6858_tiocmset(port, NULL, x, 0);
 819
 820                 case TIOCMBIC:
 821                         if (copy_from_user(&x, user_arg, sizeof(x)))
 822                                 return -EFAULT;
 823                         return oti6858_tiocmset(port, NULL, 0, x);
 824
 825                 case TIOCMIWAIT:
 826                         dbg("%s(): TIOCMIWAIT", __func__);
 827                         return wait_modem_info(port, arg);
 828
 829                 default:
 830                         dbg("%s(): 0x%04x not supported", __func__, cmd);
 831                         break;
 832         }
 833
 834         return -ENOIOCTLCMD;
 835 }
 836
 837 static void oti6858_break_ctl(struct usb_serial_port *port, int break_state)
 838 {
 839         int state;
 840
 841         dbg("%s(port = %d)", __func__, port->number);
 842
 843         state = (break_state == 0) ? 0 : 1;
 844         dbg("%s(): turning break %s", __func__, state ? "on" : "off");
 845
 846         /* FIXME */
 847 /*
 848         result = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
 849                                   BREAK_REQUEST, BREAK_REQUEST_TYPE, state,
 850                                   0, NULL, 0, 100);
 851         if (result != 0)
 852                 dbg("%s(): error sending break", __func__);
 853  */
 854 }
 855
 856 static void oti6858_shutdown(struct usb_serial *serial)
 857 {
 858         struct oti6858_private *priv;
 859         int i;
 860
 861         dbg("%s()", __func__);
 862
 863         for (i = 0; i < serial->num_ports; ++i) {
 864                 priv = usb_get_serial_port_data(serial->port[i]);
 865                 if (priv) {
 866                         oti6858_buf_free(priv->buf);
 867                         kfree(priv);
 868                         usb_set_serial_port_data(serial->port[i], NULL);
 869                 }
 870         }
 871 }
 872
 873 static void oti6858_read_int_callback(struct urb *urb)
 874 {
 875         struct usb_serial_port *port =  urb->context;
 876         struct oti6858_private *priv = usb_get_serial_port_data(port);
 877         int transient = 0, can_recv = 0, resubmit = 1;
 878         int status = urb->status;
 879
 880         dbg("%s(port = %d, status = %d)",
 881                                 __func__, port->number, status);
 882
 883         switch (status) {
 884         case 0:
 885                 /* success */
 886                 break;
 887         case -ECONNRESET:
 888         case -ENOENT:
 889         case -ESHUTDOWN:
 890                 /* this urb is terminated, clean up */
 891                 dbg("%s(): urb shutting down with status: %d",
 892                                         __func__, status);
 893                 return;
 894         default:
 895                 dbg("%s(): nonzero urb status received: %d",
 896                                         __func__, status);
 897                 break;
 898         }
 899
 900         if (status == 0 && urb->actual_length == OTI6858_CTRL_PKT_SIZE) {
 901                 struct oti6858_control_pkt *xs = urb->transfer_buffer;
 902                 unsigned long flags;
 903
 904                 spin_lock_irqsave(&priv->lock, flags);
 905
 906                 if (!priv->transient) {
 907                         if (!OTI6858_CTRL_EQUALS_PENDING(xs, priv)) {
 908                                 if (xs->rx_bytes_avail == 0) {
 909                                         priv->transient = 4;
 910                                         priv->setup_done = 0;
 911                                         resubmit = 0;
 912                                         dbg("%s(): scheduling setup_line()",
 913                                             __func__);
 914                                         schedule_delayed_work(&priv->delayed_setup_work, 0);
 915                                 }
 916                         }
 917                 } else {
 918                         if (OTI6858_CTRL_EQUALS_PENDING(xs, priv)) {
 919                                 priv->transient = 0;
 920                         } else if (!priv->setup_done) {
 921                                 resubmit = 0;
 922                         } else if (--priv->transient == 0) {
 923                                 if (xs->rx_bytes_avail == 0) {
 924                                         priv->transient = 4;
 925                                         priv->setup_done = 0;
 926                                         resubmit = 0;
 927                                         dbg("%s(): scheduling setup_line()",
 928                                             __func__);
 929                                         schedule_delayed_work(&priv->delayed_setup_work, 0);
 930                                 }
 931                         }
 932                 }
 933
 934                 if (!priv->transient) {
 935                         if (xs->pin_state != priv->status.pin_state)
 936                                 wake_up_interruptible(&priv->intr_wait);
 937                         memcpy(&priv->status, xs, OTI6858_CTRL_PKT_SIZE);
 938                 }
 939
 940                 if (!priv->transient && xs->rx_bytes_avail != 0) {
 941                         can_recv = xs->rx_bytes_avail;
 942                         priv->flags.read_urb_in_use = 1;
 943                 }
 944
 945                 transient = priv->transient;
 946                 spin_unlock_irqrestore(&priv->lock, flags);
 947         }
 948
 949         if (can_recv) {
 950                 int result;
 951
 952                 port->read_urb->dev = port->serial->dev;
 953                 result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
 954                 if (result != 0) {
 955                         priv->flags.read_urb_in_use = 0;
 956                         dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
 957                                         " error %d\n", __func__, result);
 958                 } else {
 959                         resubmit = 0;
 960                 }
 961         } else if (!transient) {
 962                 unsigned long flags;
 963
 964                 spin_lock_irqsave(&priv->lock, flags);
 965                 if (priv->flags.write_urb_in_use == 0
 966                                 && oti6858_buf_data_avail(priv->buf) != 0) {
 967                         schedule_delayed_work(&priv->delayed_write_work,0);
 968                         resubmit = 0;
 969                 }
 970                 spin_unlock_irqrestore(&priv->lock, flags);
 971         }
 972
 973         if (resubmit) {
 974                 int result;
 975
 976 //              dbg("%s(): submitting interrupt urb", __func__);
 977                 urb->dev = port->serial->dev;
 978                 result = usb_submit_urb(urb, GFP_ATOMIC);
 979                 if (result != 0) {
 980                         dev_err(&urb->dev->dev,
 981                                         "%s(): usb_submit_urb() failed with"
 982                                         " error %d\n", __func__, result);
 983                 }
 984         }
 985 }
 986
 987 static void oti6858_read_bulk_callback(struct urb *urb)
 988 {
 989         struct usb_serial_port *port =  urb->context;
 990         struct oti6858_private *priv = usb_get_serial_port_data(port);
 991         struct tty_struct *tty;
 992         unsigned char *data = urb->transfer_buffer;
 993         unsigned long flags;
 994         int status = urb->status;
 995         int result;
 996
 997         dbg("%s(port = %d, status = %d)",
 998                                 __func__, port->number, status);
 999
1000         spin_lock_irqsave(&priv->lock, flags);
1001         priv->flags.read_urb_in_use = 0;
1002         spin_unlock_irqrestore(&priv->lock, flags);
1003
1004         if (status != 0) {
1005                 if (!port->open_count) {
1006                         dbg("%s(): port is closed, exiting", __func__);
1007                         return;
1008                 }
1009                 /*
1010                 if (status == -EPROTO) {
1011                         // PL2303 mysteriously fails with -EPROTO reschedule the read
1012                         dbg("%s - caught -EPROTO, resubmitting the urb", __func__);
1013                         result = usb_submit_urb(urb, GFP_ATOMIC);
1014                         if (result)
1015                                 dev_err(&urb->dev->dev, "%s - failed resubmitting read urb, error %d\n", __func__, result);
1016                         return;
1017                 }
1018                 */
1019                 dbg("%s(): unable to handle the error, exiting", __func__);
1020                 return;
1021         }
1022
1023         tty = port->tty;
1024         if (tty != NULL && urb->actual_length > 0) {
1025                 tty_insert_flip_string(tty, data, urb->actual_length);
1026                 tty_flip_buffer_push(tty);
1027         }
1028
1029         // schedule the interrupt urb if we are still open */
1030         if (port->open_count != 0) {
1031                 port->interrupt_in_urb->dev = port->serial->dev;
1032                 result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
1033                 if (result != 0) {
1034                         dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
1035                                         " error %d\n", __func__, result);
1036                 }
1037         }
1038 }
1039
1040 static void oti6858_write_bulk_callback(struct urb *urb)
1041 {
1042         struct usb_serial_port *port =  urb->context;
1043         struct oti6858_private *priv = usb_get_serial_port_data(port);
1044         int status = urb->status;
1045         int result;
1046
1047         dbg("%s(port = %d, status = %d)",
1048                                 __func__, port->number, status);
1049
1050         switch (status) {
1051         case 0:
1052                 /* success */
1053                 break;
1054         case -ECONNRESET:
1055         case -ENOENT:
1056         case -ESHUTDOWN:
1057                 /* this urb is terminated, clean up */
1058                 dbg("%s(): urb shutting down with status: %d",
1059                                         __func__, status);
1060                 priv->flags.write_urb_in_use = 0;
1061                 return;
1062         default:
1063                 /* error in the urb, so we have to resubmit it */
1064                 dbg("%s(): nonzero write bulk status received: %d",
1065                                         __func__, status);
1066                 dbg("%s(): overflow in write", __func__);
1067
1068                 port->write_urb->transfer_buffer_length = 1;
1069                 port->write_urb->dev = port->serial->dev;
1070                 result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
1071                 if (result) {
1072                         dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
1073                                         " error %d\n", __func__, result);
1074                 } else {
1075                         return;
1076                 }
1077         }
1078
1079         priv->flags.write_urb_in_use = 0;
1080
1081         // schedule the interrupt urb if we are still open */
1082         port->interrupt_in_urb->dev = port->serial->dev;
1083         dbg("%s(): submitting interrupt urb", __func__);
1084         result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
1085         if (result != 0) {
1086                 dev_err(&port->dev, "%s(): failed submitting int urb,"
1087                                         " error %d\n", __func__, result);
1088         }
1089 }
1090
1091
1092 /*
1093  * oti6858_buf_alloc
1094  *
1095  * Allocate a circular buffer and all associated memory.
1096  */
1097 static struct oti6858_buf *oti6858_buf_alloc(unsigned int size)
1098 {
1099         struct oti6858_buf *pb;
1100
1101         if (size == 0)
1102                 return NULL;
1103
1104         pb = kmalloc(sizeof(struct oti6858_buf), GFP_KERNEL);
1105         if (pb == NULL)
1106                 return NULL;
1107
1108         pb->buf_buf = kmalloc(size, GFP_KERNEL);
1109         if (pb->buf_buf == NULL) {
1110                 kfree(pb);
1111                 return NULL;
1112         }
1113
1114         pb->buf_size = size;
1115         pb->buf_get = pb->buf_put = pb->buf_buf;
1116
1117         return pb;
1118 }
1119
1120 /*
1121  * oti6858_buf_free
1122  *
1123  * Free the buffer and all associated memory.
1124  */
1125 static void oti6858_buf_free(struct oti6858_buf *pb)
1126 {
1127         if (pb) {
1128                 kfree(pb->buf_buf);
1129                 kfree(pb);
1130         }
1131 }
1132
1133 /*
1134  * oti6858_buf_clear
1135  *
1136  * Clear out all data in the circular buffer.
1137  */
1138 static void oti6858_buf_clear(struct oti6858_buf *pb)
1139 {
1140         if (pb != NULL) {
1141                 /* equivalent to a get of all data available */
1142                 pb->buf_get = pb->buf_put;
1143         }
1144 }
1145
1146 /*
1147  * oti6858_buf_data_avail
1148  *
1149  * Return the number of bytes of data available in the circular
1150  * buffer.
1151  */
1152 static unsigned int oti6858_buf_data_avail(struct oti6858_buf *pb)
1153 {
1154         if (pb == NULL)
1155                 return 0;
1156         return ((pb->buf_size + pb->buf_put - pb->buf_get) % pb->buf_size);
1157 }
1158
1159 /*
1160  * oti6858_buf_space_avail
1161  *
1162  * Return the number of bytes of space available in the circular
1163  * buffer.
1164  */
1165 static unsigned int oti6858_buf_space_avail(struct oti6858_buf *pb)
1166 {
1167         if (pb == NULL)
1168                 return 0;
1169         return ((pb->buf_size + pb->buf_get - pb->buf_put - 1) % pb->buf_size);
1170 }
1171
1172 /*
1173  * oti6858_buf_put
1174  *
1175  * Copy data data from a user buffer and put it into the circular buffer.
1176  * Restrict to the amount of space available.
1177  *
1178  * Return the number of bytes copied.
1179  */
1180 static unsigned int oti6858_buf_put(struct oti6858_buf *pb, const char *buf,
1181                                         unsigned int count)
1182 {
1183         unsigned int len;
1184
1185         if (pb == NULL)
1186                 return 0;
1187
1188         len  = oti6858_buf_space_avail(pb);
1189         if (count > len)
1190                 count = len;
1191
1192         if (count == 0)
1193                 return 0;
1194
1195         len = pb->buf_buf + pb->buf_size - pb->buf_put;
1196         if (count > len) {
1197                 memcpy(pb->buf_put, buf, len);
1198                 memcpy(pb->buf_buf, buf+len, count - len);
1199                 pb->buf_put = pb->buf_buf + count - len;
1200         } else {
1201                 memcpy(pb->buf_put, buf, count);
1202                 if (count < len)
1203                         pb->buf_put += count;
1204                 else /* count == len */
1205                         pb->buf_put = pb->buf_buf;
1206         }
1207
1208         return count;
1209 }
1210
1211 /*
1212  * oti6858_buf_get
1213  *
1214  * Get data from the circular buffer and copy to the given buffer.
1215  * Restrict to the amount of data available.
1216  *
1217  * Return the number of bytes copied.
1218  */
1219 static unsigned int oti6858_buf_get(struct oti6858_buf *pb, char *buf,
1220                                         unsigned int count)
1221 {
1222         unsigned int len;
1223
1224         if (pb == NULL)
1225                 return 0;
1226
1227         len = oti6858_buf_data_avail(pb);
1228         if (count > len)
1229                 count = len;
1230
1231         if (count == 0)
1232                 return 0;
1233
1234         len = pb->buf_buf + pb->buf_size - pb->buf_get;
1235         if (count > len) {
1236                 memcpy(buf, pb->buf_get, len);
1237                 memcpy(buf+len, pb->buf_buf, count - len);
1238                 pb->buf_get = pb->buf_buf + count - len;
1239         } else {
1240                 memcpy(buf, pb->buf_get, count);
1241                 if (count < len)
1242                         pb->buf_get += count;
1243                 else /* count == len */
1244                         pb->buf_get = pb->buf_buf;
1245         }
1246
1247         return count;
1248 }
1249
1250 /* module description and (de)initialization */
1251
1252 static int __init oti6858_init(void)
1253 {
1254         int retval;
1255
1256         if ((retval = usb_serial_register(&oti6858_device)) == 0) {
1257                 if ((retval = usb_register(&oti6858_driver)) != 0)
1258                         usb_serial_deregister(&oti6858_device);
1259                 else
1260                         return 0;
1261         }
1262
1263         return retval;
1264 }
1265
1266 static void __exit oti6858_exit(void)
1267 {
1268         usb_deregister(&oti6858_driver);
1269         usb_serial_deregister(&oti6858_device);
1270 }
1271
1272 module_init(oti6858_init);
1273 module_exit(oti6858_exit);
1274
1275 MODULE_DESCRIPTION(OTI6858_DESCRIPTION);
1276 MODULE_AUTHOR(OTI6858_AUTHOR);
1277 MODULE_VERSION(OTI6858_VERSION);
1278 MODULE_LICENSE("GPL");
1279
1280 module_param(debug, bool, S_IRUGO | S_IWUSR);
1281 MODULE_PARM_DESC(debug, "enable debug output");
1282