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/init.h>
  20 #include <linux/tty.h>
  21 #include <linux/module.h>
  22 #include <linux/slab.h>
  23 #include <linux/usb.h>
  24 #include <linux/usb/serial.h>
  25 #include <linux/serial.h>
  26 #include <asm/unaligned.h>
  27
  28 #define DEFAULT_BAUD_RATE 9600
  29 #define DEFAULT_TIMEOUT   1000
  30
  31 /* flags for IO-Bits */
  32 #define CH341_BIT_RTS (1 << 6)
  33 #define CH341_BIT_DTR (1 << 5)
  34
  35 /******************************/
  36 /* interrupt pipe definitions */
  37 /******************************/
  38 /* always 4 interrupt bytes */
  39 /* first irq byte normally 0x08 */
  40 /* second irq byte base 0x7d + below */
  41 /* third irq byte base 0x94 + below */
  42 /* fourth irq byte normally 0xee */
  43
  44 /* second interrupt byte */
  45 #define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
  46
  47 /* status returned in third interrupt answer byte, inverted in data
  48    from irq */
  49 #define CH341_BIT_CTS 0x01
  50 #define CH341_BIT_DSR 0x02
  51 #define CH341_BIT_RI  0x04
  52 #define CH341_BIT_DCD 0x08
  53 #define CH341_BITS_MODEM_STAT 0x0f /* all bits */
  54
  55 /*******************************/
  56 /* baudrate calculation factor */
  57 /*******************************/
  58 #define CH341_BAUDBASE_FACTOR 1532620800
  59 #define CH341_BAUDBASE_DIVMAX 3
  60
  61 /* Break support - the information used to implement this was gleaned from
  62  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  63  */
  64
  65 #define CH341_REQ_WRITE_REG    0x9A
  66 #define CH341_REQ_READ_REG     0x95
  67 #define CH341_REG_BREAK1       0x05
  68 #define CH341_REG_BREAK2       0x18
  69 #define CH341_NBREAK_BITS_REG1 0x01
  70 #define CH341_NBREAK_BITS_REG2 0x40
  71
  72
  73 static const struct usb_device_id id_table[] = {
  74         { USB_DEVICE(0x4348, 0x5523) },
  75         { USB_DEVICE(0x1a86, 0x7523) },
  76         { USB_DEVICE(0x1a86, 0x5523) },
  77         { },
  78 };
  79 MODULE_DEVICE_TABLE(usb, id_table);
  80
  81 struct ch341_private {
  82         spinlock_t lock; /* access lock */
  83         unsigned baud_rate; /* set baud rate */
  84         u8 line_control; /* set line control value RTS/DTR */
  85         u8 line_status; /* active status of modem control inputs */
  86 };
  87
  88 static int ch341_control_out(struct usb_device *dev, u8 request,
  89                              u16 value, u16 index)
  90 {
  91         int r;
  92
  93         dev_dbg(&dev->dev, "ch341_control_out(%02x,%02x,%04x,%04x)\n",
  94                 USB_DIR_OUT|0x40, (int)request, (int)value, (int)index);
  95
  96         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
  97                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
  98                             value, index, NULL, 0, DEFAULT_TIMEOUT);
  99
 100         return r;
 101 }
 102
 103 static int ch341_control_in(struct usb_device *dev,
 104                             u8 request, u16 value, u16 index,
 105                             char *buf, unsigned bufsize)
 106 {
 107         int r;
 108
 109         dev_dbg(&dev->dev, "ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)\n",
 110                 USB_DIR_IN|0x40, (int)request, (int)value, (int)index, buf,
 111                 (int)bufsize);
 112
 113         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 114                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 115                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 116         return r;
 117 }
 118
 119 static int ch341_set_baudrate(struct usb_device *dev,
 120                               struct ch341_private *priv)
 121 {
 122         short a, b;
 123         int r;
 124         unsigned long factor;
 125         short divisor;
 126
 127         if (!priv->baud_rate)
 128                 return -EINVAL;
 129         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 130         divisor = CH341_BAUDBASE_DIVMAX;
 131
 132         while ((factor > 0xfff0) && divisor) {
 133                 factor >>= 3;
 134                 divisor--;
 135         }
 136
 137         if (factor > 0xfff0)
 138                 return -EINVAL;
 139
 140         factor = 0x10000 - factor;
 141         a = (factor & 0xff00) | divisor;
 142         b = factor & 0xff;
 143
 144         r = ch341_control_out(dev, 0x9a, 0x1312, a);
 145         if (!r)
 146                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
 147
 148         return r;
 149 }
 150
 151 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 152 {
 153         return ch341_control_out(dev, 0xa4, ~control, 0);
 154 }
 155
 156 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 157 {
 158         char *buffer;
 159         int r;
 160         const unsigned size = 8;
 161         unsigned long flags;
 162
 163         buffer = kmalloc(size, GFP_KERNEL);
 164         if (!buffer)
 165                 return -ENOMEM;
 166
 167         r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
 168         if (r < 0)
 169                 goto out;
 170
 171         /* setup the private status if available */
 172         if (r == 2) {
 173                 r = 0;
 174                 spin_lock_irqsave(&priv->lock, flags);
 175                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 176                 spin_unlock_irqrestore(&priv->lock, flags);
 177         } else
 178                 r = -EPROTO;
 179
 180 out:    kfree(buffer);
 181         return r;
 182 }
 183
 184 /* -------------------------------------------------------------------------- */
 185
 186 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 187 {
 188         char *buffer;
 189         int r;
 190         const unsigned size = 8;
 191
 192         buffer = kmalloc(size, GFP_KERNEL);
 193         if (!buffer)
 194                 return -ENOMEM;
 195
 196         /* expect two bytes 0x27 0x00 */
 197         r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
 198         if (r < 0)
 199                 goto out;
 200
 201         r = ch341_control_out(dev, 0xa1, 0, 0);
 202         if (r < 0)
 203                 goto out;
 204
 205         r = ch341_set_baudrate(dev, priv);
 206         if (r < 0)
 207                 goto out;
 208
 209         /* expect two bytes 0x56 0x00 */
 210         r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
 211         if (r < 0)
 212                 goto out;
 213
 214         r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
 215         if (r < 0)
 216                 goto out;
 217
 218         /* expect 0xff 0xee */
 219         r = ch341_get_status(dev, priv);
 220         if (r < 0)
 221                 goto out;
 222
 223         r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
 224         if (r < 0)
 225                 goto out;
 226
 227         r = ch341_set_baudrate(dev, priv);
 228         if (r < 0)
 229                 goto out;
 230
 231         r = ch341_set_handshake(dev, priv->line_control);
 232         if (r < 0)
 233                 goto out;
 234
 235         /* expect 0x9f 0xee */
 236         r = ch341_get_status(dev, priv);
 237
 238 out:    kfree(buffer);
 239         return r;
 240 }
 241
 242 static int ch341_port_probe(struct usb_serial_port *port)
 243 {
 244         struct ch341_private *priv;
 245         int r;
 246
 247         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 248         if (!priv)
 249                 return -ENOMEM;
 250
 251         spin_lock_init(&priv->lock);
 252         priv->baud_rate = DEFAULT_BAUD_RATE;
 253         priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 254
 255         r = ch341_configure(port->serial->dev, priv);
 256         if (r < 0)
 257                 goto error;
 258
 259         usb_set_serial_port_data(port, priv);
 260         return 0;
 261
 262 error:  kfree(priv);
 263         return r;
 264 }
 265
 266 static int ch341_port_remove(struct usb_serial_port *port)
 267 {
 268         struct ch341_private *priv;
 269
 270         priv = usb_get_serial_port_data(port);
 271         kfree(priv);
 272
 273         return 0;
 274 }
 275
 276 static int ch341_carrier_raised(struct usb_serial_port *port)
 277 {
 278         struct ch341_private *priv = usb_get_serial_port_data(port);
 279         if (priv->line_status & CH341_BIT_DCD)
 280                 return 1;
 281         return 0;
 282 }
 283
 284 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 285 {
 286         struct ch341_private *priv = usb_get_serial_port_data(port);
 287         unsigned long flags;
 288
 289         /* drop DTR and RTS */
 290         spin_lock_irqsave(&priv->lock, flags);
 291         if (on)
 292                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 293         else
 294                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 295         spin_unlock_irqrestore(&priv->lock, flags);
 296         ch341_set_handshake(port->serial->dev, priv->line_control);
 297 }
 298
 299 static void ch341_close(struct usb_serial_port *port)
 300 {
 301         usb_serial_generic_close(port);
 302         usb_kill_urb(port->interrupt_in_urb);
 303 }
 304
 305
 306 /* open this device, set default parameters */
 307 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 308 {
 309         struct usb_serial *serial = port->serial;
 310         struct ch341_private *priv = usb_get_serial_port_data(port);
 311         int r;
 312
 313         priv->baud_rate = DEFAULT_BAUD_RATE;
 314
 315         r = ch341_configure(serial->dev, priv);
 316         if (r)
 317                 goto out;
 318
 319         r = ch341_set_handshake(serial->dev, priv->line_control);
 320         if (r)
 321                 goto out;
 322
 323         r = ch341_set_baudrate(serial->dev, priv);
 324         if (r)
 325                 goto out;
 326
 327         dev_dbg(&port->dev, "%s - submitting interrupt urb", __func__);
 328         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 329         if (r) {
 330                 dev_err(&port->dev, "%s - failed submitting interrupt urb,"
 331                         " error %d\n", __func__, r);
 332                 ch341_close(port);
 333                 goto out;
 334         }
 335
 336         r = usb_serial_generic_open(tty, port);
 337
 338 out:    return r;
 339 }
 340
 341 /* Old_termios contains the original termios settings and
 342  * tty->termios contains the new setting to be used.
 343  */
 344 static void ch341_set_termios(struct tty_struct *tty,
 345                 struct usb_serial_port *port, struct ktermios *old_termios)
 346 {
 347         struct ch341_private *priv = usb_get_serial_port_data(port);
 348         unsigned baud_rate;
 349         unsigned long flags;
 350
 351         baud_rate = tty_get_baud_rate(tty);
 352
 353         priv->baud_rate = baud_rate;
 354
 355         if (baud_rate) {
 356                 spin_lock_irqsave(&priv->lock, flags);
 357                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 358                 spin_unlock_irqrestore(&priv->lock, flags);
 359                 ch341_set_baudrate(port->serial->dev, priv);
 360         } else {
 361                 spin_lock_irqsave(&priv->lock, flags);
 362                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 363                 spin_unlock_irqrestore(&priv->lock, flags);
 364         }
 365
 366         ch341_set_handshake(port->serial->dev, priv->line_control);
 367
 368         /* Unimplemented:
 369          * (cflag & CSIZE) : data bits [5, 8]
 370          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 371          * (cflag & CSTOPB) : stop bits [1, 2]
 372          */
 373 }
 374
 375 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 376 {
 377         const uint16_t ch341_break_reg =
 378                 CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
 379         struct usb_serial_port *port = tty->driver_data;
 380         int r;
 381         uint16_t reg_contents;
 382         uint8_t *break_reg;
 383
 384         break_reg = kmalloc(2, GFP_KERNEL);
 385         if (!break_reg)
 386                 return;
 387
 388         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 389                         ch341_break_reg, 0, break_reg, 2);
 390         if (r < 0) {
 391                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 392                                 __func__, r);
 393                 goto out;
 394         }
 395         dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 396                 __func__, break_reg[0], break_reg[1]);
 397         if (break_state != 0) {
 398                 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 399                 break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
 400                 break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
 401         } else {
 402                 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 403                 break_reg[0] |= CH341_NBREAK_BITS_REG1;
 404                 break_reg[1] |= CH341_NBREAK_BITS_REG2;
 405         }
 406         dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 407                 __func__, break_reg[0], break_reg[1]);
 408         reg_contents = get_unaligned_le16(break_reg);
 409         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 410                         ch341_break_reg, reg_contents);
 411         if (r < 0)
 412                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 413                                 __func__, r);
 414 out:
 415         kfree(break_reg);
 416 }
 417
 418 static int ch341_tiocmset(struct tty_struct *tty,
 419                           unsigned int set, unsigned int clear)
 420 {
 421         struct usb_serial_port *port = tty->driver_data;
 422         struct ch341_private *priv = usb_get_serial_port_data(port);
 423         unsigned long flags;
 424         u8 control;
 425
 426         spin_lock_irqsave(&priv->lock, flags);
 427         if (set & TIOCM_RTS)
 428                 priv->line_control |= CH341_BIT_RTS;
 429         if (set & TIOCM_DTR)
 430                 priv->line_control |= CH341_BIT_DTR;
 431         if (clear & TIOCM_RTS)
 432                 priv->line_control &= ~CH341_BIT_RTS;
 433         if (clear & TIOCM_DTR)
 434                 priv->line_control &= ~CH341_BIT_DTR;
 435         control = priv->line_control;
 436         spin_unlock_irqrestore(&priv->lock, flags);
 437
 438         return ch341_set_handshake(port->serial->dev, control);
 439 }
 440
 441 static void ch341_update_line_status(struct usb_serial_port *port,
 442                                         unsigned char *data, size_t len)
 443 {
 444         struct ch341_private *priv = usb_get_serial_port_data(port);
 445         struct tty_struct *tty;
 446         unsigned long flags;
 447         u8 status;
 448         u8 delta;
 449
 450         if (len < 4)
 451                 return;
 452
 453         status = ~data[2] & CH341_BITS_MODEM_STAT;
 454
 455         spin_lock_irqsave(&priv->lock, flags);
 456         delta = status ^ priv->line_status;
 457         priv->line_status = status;
 458         spin_unlock_irqrestore(&priv->lock, flags);
 459
 460         if (data[1] & CH341_MULT_STAT)
 461                 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
 462
 463         if (!delta)
 464                 return;
 465
 466         if (delta & CH341_BIT_CTS)
 467                 port->icount.cts++;
 468         if (delta & CH341_BIT_DSR)
 469                 port->icount.dsr++;
 470         if (delta & CH341_BIT_RI)
 471                 port->icount.rng++;
 472         if (delta & CH341_BIT_DCD) {
 473                 port->icount.dcd++;
 474                 tty = tty_port_tty_get(&port->port);
 475                 if (tty) {
 476                         usb_serial_handle_dcd_change(port, tty,
 477                                                 status & CH341_BIT_DCD);
 478                         tty_kref_put(tty);
 479                 }
 480         }
 481
 482         wake_up_interruptible(&port->port.delta_msr_wait);
 483 }
 484
 485 static void ch341_read_int_callback(struct urb *urb)
 486 {
 487         struct usb_serial_port *port = urb->context;
 488         unsigned char *data = urb->transfer_buffer;
 489         unsigned int len = urb->actual_length;
 490         int status;
 491
 492         switch (urb->status) {
 493         case 0:
 494                 /* success */
 495                 break;
 496         case -ECONNRESET:
 497         case -ENOENT:
 498         case -ESHUTDOWN:
 499                 /* this urb is terminated, clean up */
 500                 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
 501                         __func__, urb->status);
 502                 return;
 503         default:
 504                 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
 505                         __func__, urb->status);
 506                 goto exit;
 507         }
 508
 509         usb_serial_debug_data(&port->dev, __func__, len, data);
 510         ch341_update_line_status(port, data, len);
 511 exit:
 512         status = usb_submit_urb(urb, GFP_ATOMIC);
 513         if (status) {
 514                 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
 515                         __func__, status);
 516         }
 517 }
 518
 519 static int ch341_tiocmget(struct tty_struct *tty)
 520 {
 521         struct usb_serial_port *port = tty->driver_data;
 522         struct ch341_private *priv = usb_get_serial_port_data(port);
 523         unsigned long flags;
 524         u8 mcr;
 525         u8 status;
 526         unsigned int result;
 527
 528         spin_lock_irqsave(&priv->lock, flags);
 529         mcr = priv->line_control;
 530         status = priv->line_status;
 531         spin_unlock_irqrestore(&priv->lock, flags);
 532
 533         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 534                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 535                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 536                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 537                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 538                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 539
 540         dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 541
 542         return result;
 543 }
 544
 545 static int ch341_reset_resume(struct usb_serial *serial)
 546 {
 547         struct ch341_private *priv;
 548
 549         priv = usb_get_serial_port_data(serial->port[0]);
 550
 551         /* reconfigure ch341 serial port after bus-reset */
 552         ch341_configure(serial->dev, priv);
 553
 554         return 0;
 555 }
 556
 557 static struct usb_serial_driver ch341_device = {
 558         .driver = {
 559                 .owner  = THIS_MODULE,
 560                 .name   = "ch341-uart",
 561         },
 562         .id_table          = id_table,
 563         .num_ports         = 1,
 564         .open              = ch341_open,
 565         .dtr_rts           = ch341_dtr_rts,
 566         .carrier_raised    = ch341_carrier_raised,
 567         .close             = ch341_close,
 568         .set_termios       = ch341_set_termios,
 569         .break_ctl         = ch341_break_ctl,
 570         .tiocmget          = ch341_tiocmget,
 571         .tiocmset          = ch341_tiocmset,
 572         .tiocmiwait        = usb_serial_generic_tiocmiwait,
 573         .read_int_callback = ch341_read_int_callback,
 574         .port_probe        = ch341_port_probe,
 575         .port_remove       = ch341_port_remove,
 576         .reset_resume      = ch341_reset_resume,
 577 };
 578
 579 static struct usb_serial_driver * const serial_drivers[] = {
 580         &ch341_device, NULL
 581 };
 582
 583 module_usb_serial_driver(serial_drivers, id_table);
 584
 585 MODULE_LICENSE("GPL");