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