drivers/usb/serial/ch341.c

   1 /*
   2  * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
   3  * Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
   4  * Copyright 2009, Boris Hajduk <boris@hajduk.org>
   5  *
   6  * ch341.c implements a serial port driver for the Winchiphead CH341.
   7  *
   8  * The CH341 device can be used to implement an RS232 asynchronous
   9  * serial port, an IEEE-1284 parallel printer port or a memory-like
  10  * interface. In all cases the CH341 supports an I2C interface as well.
  11  * This driver only supports the asynchronous serial interface.
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License version
  15  * 2 as published by the Free Software Foundation.
  16  */
  17
  18 #include <linux/kernel.h>
  19 #include <linux/tty.h>
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/usb.h>
  23 #include <linux/usb/serial.h>
  24 #include <linux/serial.h>
  25 #include <asm/unaligned.h>
  26
  27 #define DEFAULT_BAUD_RATE 9600
  28 #define DEFAULT_TIMEOUT   1000
  29
  30 /* flags for IO-Bits */
  31 #define CH341_BIT_RTS (1 << 6)
  32 #define CH341_BIT_DTR (1 << 5)
  33
  34 /******************************/
  35 /* interrupt pipe definitions */
  36 /******************************/
  37 /* always 4 interrupt bytes */
  38 /* first irq byte normally 0x08 */
  39 /* second irq byte base 0x7d + below */
  40 /* third irq byte base 0x94 + below */
  41 /* fourth irq byte normally 0xee */
  42
  43 /* second interrupt byte */
  44 #define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
  45
  46 /* status returned in third interrupt answer byte, inverted in data
  47    from irq */
  48 #define CH341_BIT_CTS 0x01
  49 #define CH341_BIT_DSR 0x02
  50 #define CH341_BIT_RI  0x04
  51 #define CH341_BIT_DCD 0x08
  52 #define CH341_BITS_MODEM_STAT 0x0f /* all bits */
  53
  54 /*******************************/
  55 /* baudrate calculation factor */
  56 /*******************************/
  57 #define CH341_BAUDBASE_FACTOR 1532620800
  58 #define CH341_BAUDBASE_DIVMAX 3
  59
  60 /* Break support - the information used to implement this was gleaned from
  61  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  62  */
  63
  64 #define CH341_REQ_READ_VERSION 0x5F
  65 #define CH341_REQ_WRITE_REG    0x9A
  66 #define CH341_REQ_READ_REG     0x95
  67 #define CH341_REQ_SERIAL_INIT  0xA1
  68 #define CH341_REQ_MODEM_CTRL   0xA4
  69
  70 #define CH341_REG_BREAK        0x05
  71 #define CH341_REG_LCR          0x18
  72 #define CH341_NBREAK_BITS      0x01
  73
  74 #define CH341_LCR_ENABLE_RX    0x80
  75 #define CH341_LCR_ENABLE_TX    0x40
  76 #define CH341_LCR_MARK_SPACE   0x20
  77 #define CH341_LCR_PAR_EVEN     0x10
  78 #define CH341_LCR_ENABLE_PAR   0x08
  79 #define CH341_LCR_STOP_BITS_2  0x04
  80 #define CH341_LCR_CS8          0x03
  81 #define CH341_LCR_CS7          0x02
  82 #define CH341_LCR_CS6          0x01
  83 #define CH341_LCR_CS5          0x00
  84
  85 static const struct usb_device_id id_table[] = {
  86         { USB_DEVICE(0x4348, 0x5523) },
  87         { USB_DEVICE(0x1a86, 0x7523) },
  88         { USB_DEVICE(0x1a86, 0x5523) },
  89         { },
  90 };
  91 MODULE_DEVICE_TABLE(usb, id_table);
  92
  93 struct ch341_private {
  94         spinlock_t lock; /* access lock */
  95         unsigned baud_rate; /* set baud rate */
  96         u8 line_control; /* set line control value RTS/DTR */
  97         u8 line_status; /* active status of modem control inputs */
  98         u8 lcr;
  99 };
 100
 101 static void ch341_set_termios(struct tty_struct *tty,
 102                               struct usb_serial_port *port,
 103                               struct ktermios *old_termios);
 104
 105 static int ch341_control_out(struct usb_device *dev, u8 request,
 106                              u16 value, u16 index)
 107 {
 108         int r;
 109
 110         dev_dbg(&dev->dev, "ch341_control_out(%02x,%02x,%04x,%04x)\n",
 111                 USB_DIR_OUT|0x40, (int)request, (int)value, (int)index);
 112
 113         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 114                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 115                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 116
 117         return r;
 118 }
 119
 120 static int ch341_control_in(struct usb_device *dev,
 121                             u8 request, u16 value, u16 index,
 122                             char *buf, unsigned bufsize)
 123 {
 124         int r;
 125
 126         dev_dbg(&dev->dev, "ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)\n",
 127                 USB_DIR_IN|0x40, (int)request, (int)value, (int)index, buf,
 128                 (int)bufsize);
 129
 130         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 131                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 132                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 133         return r;
 134 }
 135
 136 static int ch341_init_set_baudrate(struct usb_device *dev,
 137                                    struct ch341_private *priv, unsigned ctrl)
 138 {
 139         short a;
 140         int r;
 141         unsigned long factor;
 142         short divisor;
 143
 144         if (!priv->baud_rate)
 145                 return -EINVAL;
 146         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 147         divisor = CH341_BAUDBASE_DIVMAX;
 148
 149         while ((factor > 0xfff0) && divisor) {
 150                 factor >>= 3;
 151                 divisor--;
 152         }
 153
 154         if (factor > 0xfff0)
 155                 return -EINVAL;
 156
 157         factor = 0x10000 - factor;
 158         a = (factor & 0xff00) | divisor;
 159
 160         /* 0x9c is "enable SFR_UART Control register and timer" */
 161         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT,
 162                               0x9c | (ctrl << 8), a | 0x80);
 163
 164         return r;
 165 }
 166
 167 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 168 {
 169         return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
 170 }
 171
 172 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 173 {
 174         char *buffer;
 175         int r;
 176         const unsigned size = 8;
 177         unsigned long flags;
 178
 179         buffer = kmalloc(size, GFP_KERNEL);
 180         if (!buffer)
 181                 return -ENOMEM;
 182
 183         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
 184         if (r < 0)
 185                 goto out;
 186
 187         /* setup the private status if available */
 188         if (r == 2) {
 189                 r = 0;
 190                 spin_lock_irqsave(&priv->lock, flags);
 191                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 192                 spin_unlock_irqrestore(&priv->lock, flags);
 193         } else
 194                 r = -EPROTO;
 195
 196 out:    kfree(buffer);
 197         return r;
 198 }
 199
 200 /* -------------------------------------------------------------------------- */
 201
 202 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 203 {
 204         char *buffer;
 205         int r;
 206         const unsigned size = 8;
 207
 208         buffer = kmalloc(size, GFP_KERNEL);
 209         if (!buffer)
 210                 return -ENOMEM;
 211
 212         /* expect two bytes 0x27 0x00 */
 213         r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
 214         if (r < 0)
 215                 goto out;
 216         dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
 217
 218         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
 219         if (r < 0)
 220                 goto out;
 221
 222         /* expect two bytes 0x56 0x00 */
 223         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size);
 224         if (r < 0)
 225                 goto out;
 226
 227         r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, 0x0050);
 228         if (r < 0)
 229                 goto out;
 230
 231         /* expect 0xff 0xee */
 232         r = ch341_get_status(dev, priv);
 233         if (r < 0)
 234                 goto out;
 235
 236         r = ch341_init_set_baudrate(dev, priv, priv->lcr);
 237         if (r < 0)
 238                 goto out;
 239
 240         r = ch341_set_handshake(dev, priv->line_control);
 241         if (r < 0)
 242                 goto out;
 243
 244         /* expect 0x9f 0xee */
 245         r = ch341_get_status(dev, priv);
 246
 247 out:    kfree(buffer);
 248         return r;
 249 }
 250
 251 static int ch341_port_probe(struct usb_serial_port *port)
 252 {
 253         struct ch341_private *priv;
 254         int r;
 255
 256         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 257         if (!priv)
 258                 return -ENOMEM;
 259
 260         spin_lock_init(&priv->lock);
 261         priv->baud_rate = DEFAULT_BAUD_RATE;
 262
 263         r = ch341_configure(port->serial->dev, priv);
 264         if (r < 0)
 265                 goto error;
 266
 267         usb_set_serial_port_data(port, priv);
 268         return 0;
 269
 270 error:  kfree(priv);
 271         return r;
 272 }
 273
 274 static int ch341_port_remove(struct usb_serial_port *port)
 275 {
 276         struct ch341_private *priv;
 277
 278         priv = usb_get_serial_port_data(port);
 279         kfree(priv);
 280
 281         return 0;
 282 }
 283
 284 static int ch341_carrier_raised(struct usb_serial_port *port)
 285 {
 286         struct ch341_private *priv = usb_get_serial_port_data(port);
 287         if (priv->line_status & CH341_BIT_DCD)
 288                 return 1;
 289         return 0;
 290 }
 291
 292 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 293 {
 294         struct ch341_private *priv = usb_get_serial_port_data(port);
 295         unsigned long flags;
 296
 297         /* drop DTR and RTS */
 298         spin_lock_irqsave(&priv->lock, flags);
 299         if (on)
 300                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 301         else
 302                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 303         spin_unlock_irqrestore(&priv->lock, flags);
 304         ch341_set_handshake(port->serial->dev, priv->line_control);
 305 }
 306
 307 static void ch341_close(struct usb_serial_port *port)
 308 {
 309         usb_serial_generic_close(port);
 310         usb_kill_urb(port->interrupt_in_urb);
 311 }
 312
 313
 314 /* open this device, set default parameters */
 315 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 316 {
 317         struct usb_serial *serial = port->serial;
 318         struct ch341_private *priv = usb_get_serial_port_data(port);
 319         int r;
 320
 321         r = ch341_configure(serial->dev, priv);
 322         if (r)
 323                 return r;
 324
 325         if (tty)
 326                 ch341_set_termios(tty, port, NULL);
 327
 328         dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
 329         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 330         if (r) {
 331                 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
 332                         __func__, r);
 333                 return r;
 334         }
 335
 336         r = usb_serial_generic_open(tty, port);
 337         if (r)
 338                 goto err_kill_interrupt_urb;
 339
 340         return 0;
 341
 342 err_kill_interrupt_urb:
 343         usb_kill_urb(port->interrupt_in_urb);
 344
 345         return r;
 346 }
 347
 348 /* Old_termios contains the original termios settings and
 349  * tty->termios contains the new setting to be used.
 350  */
 351 static void ch341_set_termios(struct tty_struct *tty,
 352                 struct usb_serial_port *port, struct ktermios *old_termios)
 353 {
 354         struct ch341_private *priv = usb_get_serial_port_data(port);
 355         unsigned baud_rate;
 356         unsigned long flags;
 357         unsigned char ctrl;
 358         int r;
 359
 360         /* redundant changes may cause the chip to lose bytes */
 361         if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 362                 return;
 363
 364         baud_rate = tty_get_baud_rate(tty);
 365
 366         ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 367
 368         switch (C_CSIZE(tty)) {
 369         case CS5:
 370                 ctrl |= CH341_LCR_CS5;
 371                 break;
 372         case CS6:
 373                 ctrl |= CH341_LCR_CS6;
 374                 break;
 375         case CS7:
 376                 ctrl |= CH341_LCR_CS7;
 377                 break;
 378         case CS8:
 379                 ctrl |= CH341_LCR_CS8;
 380                 break;
 381         }
 382
 383         if (C_PARENB(tty)) {
 384                 ctrl |= CH341_LCR_ENABLE_PAR;
 385                 if (C_PARODD(tty) == 0)
 386                         ctrl |= CH341_LCR_PAR_EVEN;
 387                 if (C_CMSPAR(tty))
 388                         ctrl |= CH341_LCR_MARK_SPACE;
 389         }
 390
 391         if (C_CSTOPB(tty))
 392                 ctrl |= CH341_LCR_STOP_BITS_2;
 393
 394         if (baud_rate) {
 395                 priv->baud_rate = baud_rate;
 396
 397                 r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
 398                 if (r < 0 && old_termios) {
 399                         priv->baud_rate = tty_termios_baud_rate(old_termios);
 400                         tty_termios_copy_hw(&tty->termios, old_termios);
 401                 } else if (r == 0) {
 402                         priv->lcr = ctrl;
 403                 }
 404         }
 405
 406         spin_lock_irqsave(&priv->lock, flags);
 407         if (C_BAUD(tty) == B0)
 408                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 409         else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
 410                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 411         spin_unlock_irqrestore(&priv->lock, flags);
 412
 413         ch341_set_handshake(port->serial->dev, priv->line_control);
 414 }
 415
 416 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 417 {
 418         const uint16_t ch341_break_reg =
 419                         ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 420         struct usb_serial_port *port = tty->driver_data;
 421         int r;
 422         uint16_t reg_contents;
 423         uint8_t *break_reg;
 424
 425         break_reg = kmalloc(2, GFP_KERNEL);
 426         if (!break_reg)
 427                 return;
 428
 429         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 430                         ch341_break_reg, 0, break_reg, 2);
 431         if (r < 0) {
 432                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 433                                 __func__, r);
 434                 goto out;
 435         }
 436         dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 437                 __func__, break_reg[0], break_reg[1]);
 438         if (break_state != 0) {
 439                 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 440                 break_reg[0] &= ~CH341_NBREAK_BITS;
 441                 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 442         } else {
 443                 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 444                 break_reg[0] |= CH341_NBREAK_BITS;
 445                 break_reg[1] |= CH341_LCR_ENABLE_TX;
 446         }
 447         dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 448                 __func__, break_reg[0], break_reg[1]);
 449         reg_contents = get_unaligned_le16(break_reg);
 450         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 451                         ch341_break_reg, reg_contents);
 452         if (r < 0)
 453                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 454                                 __func__, r);
 455 out:
 456         kfree(break_reg);
 457 }
 458
 459 static int ch341_tiocmset(struct tty_struct *tty,
 460                           unsigned int set, unsigned int clear)
 461 {
 462         struct usb_serial_port *port = tty->driver_data;
 463         struct ch341_private *priv = usb_get_serial_port_data(port);
 464         unsigned long flags;
 465         u8 control;
 466
 467         spin_lock_irqsave(&priv->lock, flags);
 468         if (set & TIOCM_RTS)
 469                 priv->line_control |= CH341_BIT_RTS;
 470         if (set & TIOCM_DTR)
 471                 priv->line_control |= CH341_BIT_DTR;
 472         if (clear & TIOCM_RTS)
 473                 priv->line_control &= ~CH341_BIT_RTS;
 474         if (clear & TIOCM_DTR)
 475                 priv->line_control &= ~CH341_BIT_DTR;
 476         control = priv->line_control;
 477         spin_unlock_irqrestore(&priv->lock, flags);
 478
 479         return ch341_set_handshake(port->serial->dev, control);
 480 }
 481
 482 static void ch341_update_line_status(struct usb_serial_port *port,
 483                                         unsigned char *data, size_t len)
 484 {
 485         struct ch341_private *priv = usb_get_serial_port_data(port);
 486         struct tty_struct *tty;
 487         unsigned long flags;
 488         u8 status;
 489         u8 delta;
 490
 491         if (len < 4)
 492                 return;
 493
 494         status = ~data[2] & CH341_BITS_MODEM_STAT;
 495
 496         spin_lock_irqsave(&priv->lock, flags);
 497         delta = status ^ priv->line_status;
 498         priv->line_status = status;
 499         spin_unlock_irqrestore(&priv->lock, flags);
 500
 501         if (data[1] & CH341_MULT_STAT)
 502                 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
 503
 504         if (!delta)
 505                 return;
 506
 507         if (delta & CH341_BIT_CTS)
 508                 port->icount.cts++;
 509         if (delta & CH341_BIT_DSR)
 510                 port->icount.dsr++;
 511         if (delta & CH341_BIT_RI)
 512                 port->icount.rng++;
 513         if (delta & CH341_BIT_DCD) {
 514                 port->icount.dcd++;
 515                 tty = tty_port_tty_get(&port->port);
 516                 if (tty) {
 517                         usb_serial_handle_dcd_change(port, tty,
 518                                                 status & CH341_BIT_DCD);
 519                         tty_kref_put(tty);
 520                 }
 521         }
 522
 523         wake_up_interruptible(&port->port.delta_msr_wait);
 524 }
 525
 526 static void ch341_read_int_callback(struct urb *urb)
 527 {
 528         struct usb_serial_port *port = urb->context;
 529         unsigned char *data = urb->transfer_buffer;
 530         unsigned int len = urb->actual_length;
 531         int status;
 532
 533         switch (urb->status) {
 534         case 0:
 535                 /* success */
 536                 break;
 537         case -ECONNRESET:
 538         case -ENOENT:
 539         case -ESHUTDOWN:
 540                 /* this urb is terminated, clean up */
 541                 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
 542                         __func__, urb->status);
 543                 return;
 544         default:
 545                 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
 546                         __func__, urb->status);
 547                 goto exit;
 548         }
 549
 550         usb_serial_debug_data(&port->dev, __func__, len, data);
 551         ch341_update_line_status(port, data, len);
 552 exit:
 553         status = usb_submit_urb(urb, GFP_ATOMIC);
 554         if (status) {
 555                 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
 556                         __func__, status);
 557         }
 558 }
 559
 560 static int ch341_tiocmget(struct tty_struct *tty)
 561 {
 562         struct usb_serial_port *port = tty->driver_data;
 563         struct ch341_private *priv = usb_get_serial_port_data(port);
 564         unsigned long flags;
 565         u8 mcr;
 566         u8 status;
 567         unsigned int result;
 568
 569         spin_lock_irqsave(&priv->lock, flags);
 570         mcr = priv->line_control;
 571         status = priv->line_status;
 572         spin_unlock_irqrestore(&priv->lock, flags);
 573
 574         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 575                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 576                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 577                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 578                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 579                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 580
 581         dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 582
 583         return result;
 584 }
 585
 586 static int ch341_reset_resume(struct usb_serial *serial)
 587 {
 588         struct usb_serial_port *port = serial->port[0];
 589         struct ch341_private *priv = usb_get_serial_port_data(port);
 590         int ret;
 591
 592         /* reconfigure ch341 serial port after bus-reset */
 593         ch341_configure(serial->dev, priv);
 594
 595         if (tty_port_initialized(&port->port)) {
 596                 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
 597                 if (ret) {
 598                         dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
 599                                 ret);
 600                         return ret;
 601                 }
 602         }
 603
 604         return usb_serial_generic_resume(serial);
 605 }
 606
 607 static struct usb_serial_driver ch341_device = {
 608         .driver = {
 609                 .owner  = THIS_MODULE,
 610                 .name   = "ch341-uart",
 611         },
 612         .id_table          = id_table,
 613         .num_ports         = 1,
 614         .open              = ch341_open,
 615         .dtr_rts           = ch341_dtr_rts,
 616         .carrier_raised    = ch341_carrier_raised,
 617         .close             = ch341_close,
 618         .set_termios       = ch341_set_termios,
 619         .break_ctl         = ch341_break_ctl,
 620         .tiocmget          = ch341_tiocmget,
 621         .tiocmset          = ch341_tiocmset,
 622         .tiocmiwait        = usb_serial_generic_tiocmiwait,
 623         .read_int_callback = ch341_read_int_callback,
 624         .port_probe        = ch341_port_probe,
 625         .port_remove       = ch341_port_remove,
 626         .reset_resume      = ch341_reset_resume,
 627 };
 628
 629 static struct usb_serial_driver * const serial_drivers[] = {
 630         &ch341_device, NULL
 631 };
 632
 633 module_usb_serial_driver(serial_drivers, id_table);
 634
 635 MODULE_LICENSE("GPL");