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         u8 multi_status_change; /* status changed multiple since last call */
  87 };
  88
  89 static int ch341_control_out(struct usb_device *dev, u8 request,
  90                              u16 value, u16 index)
  91 {
  92         int r;
  93
  94         dev_dbg(&dev->dev, "ch341_control_out(%02x,%02x,%04x,%04x)\n",
  95                 USB_DIR_OUT|0x40, (int)request, (int)value, (int)index);
  96
  97         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
  98                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
  99                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 100
 101         return r;
 102 }
 103
 104 static int ch341_control_in(struct usb_device *dev,
 105                             u8 request, u16 value, u16 index,
 106                             char *buf, unsigned bufsize)
 107 {
 108         int r;
 109
 110         dev_dbg(&dev->dev, "ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)\n",
 111                 USB_DIR_IN|0x40, (int)request, (int)value, (int)index, buf,
 112                 (int)bufsize);
 113
 114         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 115                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 116                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 117         return r;
 118 }
 119
 120 static int ch341_set_baudrate(struct usb_device *dev,
 121                               struct ch341_private *priv)
 122 {
 123         short a, b;
 124         int r;
 125         unsigned long factor;
 126         short divisor;
 127
 128         if (!priv->baud_rate)
 129                 return -EINVAL;
 130         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 131         divisor = CH341_BAUDBASE_DIVMAX;
 132
 133         while ((factor > 0xfff0) && divisor) {
 134                 factor >>= 3;
 135                 divisor--;
 136         }
 137
 138         if (factor > 0xfff0)
 139                 return -EINVAL;
 140
 141         factor = 0x10000 - factor;
 142         a = (factor & 0xff00) | divisor;
 143         b = factor & 0xff;
 144
 145         r = ch341_control_out(dev, 0x9a, 0x1312, a);
 146         if (!r)
 147                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
 148
 149         return r;
 150 }
 151
 152 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 153 {
 154         return ch341_control_out(dev, 0xa4, ~control, 0);
 155 }
 156
 157 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 158 {
 159         char *buffer;
 160         int r;
 161         const unsigned size = 8;
 162         unsigned long flags;
 163
 164         buffer = kmalloc(size, GFP_KERNEL);
 165         if (!buffer)
 166                 return -ENOMEM;
 167
 168         r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
 169         if (r < 0)
 170                 goto out;
 171
 172         /* setup the private status if available */
 173         if (r == 2) {
 174                 r = 0;
 175                 spin_lock_irqsave(&priv->lock, flags);
 176                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 177                 priv->multi_status_change = 0;
 178                 spin_unlock_irqrestore(&priv->lock, flags);
 179         } else
 180                 r = -EPROTO;
 181
 182 out:    kfree(buffer);
 183         return r;
 184 }
 185
 186 /* -------------------------------------------------------------------------- */
 187
 188 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 189 {
 190         char *buffer;
 191         int r;
 192         const unsigned size = 8;
 193
 194         buffer = kmalloc(size, GFP_KERNEL);
 195         if (!buffer)
 196                 return -ENOMEM;
 197
 198         /* expect two bytes 0x27 0x00 */
 199         r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
 200         if (r < 0)
 201                 goto out;
 202
 203         r = ch341_control_out(dev, 0xa1, 0, 0);
 204         if (r < 0)
 205                 goto out;
 206
 207         r = ch341_set_baudrate(dev, priv);
 208         if (r < 0)
 209                 goto out;
 210
 211         /* expect two bytes 0x56 0x00 */
 212         r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
 213         if (r < 0)
 214                 goto out;
 215
 216         r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
 217         if (r < 0)
 218                 goto out;
 219
 220         /* expect 0xff 0xee */
 221         r = ch341_get_status(dev, priv);
 222         if (r < 0)
 223                 goto out;
 224
 225         r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
 226         if (r < 0)
 227                 goto out;
 228
 229         r = ch341_set_baudrate(dev, priv);
 230         if (r < 0)
 231                 goto out;
 232
 233         r = ch341_set_handshake(dev, priv->line_control);
 234         if (r < 0)
 235                 goto out;
 236
 237         /* expect 0x9f 0xee */
 238         r = ch341_get_status(dev, priv);
 239
 240 out:    kfree(buffer);
 241         return r;
 242 }
 243
 244 static int ch341_port_probe(struct usb_serial_port *port)
 245 {
 246         struct ch341_private *priv;
 247         int r;
 248
 249         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 250         if (!priv)
 251                 return -ENOMEM;
 252
 253         spin_lock_init(&priv->lock);
 254         priv->baud_rate = DEFAULT_BAUD_RATE;
 255         priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 256
 257         r = ch341_configure(port->serial->dev, priv);
 258         if (r < 0)
 259                 goto error;
 260
 261         usb_set_serial_port_data(port, priv);
 262         return 0;
 263
 264 error:  kfree(priv);
 265         return r;
 266 }
 267
 268 static int ch341_port_remove(struct usb_serial_port *port)
 269 {
 270         struct ch341_private *priv;
 271
 272         priv = usb_get_serial_port_data(port);
 273         kfree(priv);
 274
 275         return 0;
 276 }
 277
 278 static int ch341_carrier_raised(struct usb_serial_port *port)
 279 {
 280         struct ch341_private *priv = usb_get_serial_port_data(port);
 281         if (priv->line_status & CH341_BIT_DCD)
 282                 return 1;
 283         return 0;
 284 }
 285
 286 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 287 {
 288         struct ch341_private *priv = usb_get_serial_port_data(port);
 289         unsigned long flags;
 290
 291         /* drop DTR and RTS */
 292         spin_lock_irqsave(&priv->lock, flags);
 293         if (on)
 294                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 295         else
 296                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 297         spin_unlock_irqrestore(&priv->lock, flags);
 298         ch341_set_handshake(port->serial->dev, priv->line_control);
 299 }
 300
 301 static void ch341_close(struct usb_serial_port *port)
 302 {
 303         usb_serial_generic_close(port);
 304         usb_kill_urb(port->interrupt_in_urb);
 305 }
 306
 307
 308 /* open this device, set default parameters */
 309 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 310 {
 311         struct usb_serial *serial = port->serial;
 312         struct ch341_private *priv = usb_get_serial_port_data(port);
 313         int r;
 314
 315         priv->baud_rate = DEFAULT_BAUD_RATE;
 316
 317         r = ch341_configure(serial->dev, priv);
 318         if (r)
 319                 goto out;
 320
 321         r = ch341_set_handshake(serial->dev, priv->line_control);
 322         if (r)
 323                 goto out;
 324
 325         r = ch341_set_baudrate(serial->dev, priv);
 326         if (r)
 327                 goto out;
 328
 329         dev_dbg(&port->dev, "%s - submitting interrupt urb", __func__);
 330         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 331         if (r) {
 332                 dev_err(&port->dev, "%s - failed submitting interrupt urb,"
 333                         " error %d\n", __func__, r);
 334                 ch341_close(port);
 335                 goto out;
 336         }
 337
 338         r = usb_serial_generic_open(tty, port);
 339
 340 out:    return r;
 341 }
 342
 343 /* Old_termios contains the original termios settings and
 344  * tty->termios contains the new setting to be used.
 345  */
 346 static void ch341_set_termios(struct tty_struct *tty,
 347                 struct usb_serial_port *port, struct ktermios *old_termios)
 348 {
 349         struct ch341_private *priv = usb_get_serial_port_data(port);
 350         unsigned baud_rate;
 351         unsigned long flags;
 352
 353         baud_rate = tty_get_baud_rate(tty);
 354
 355         priv->baud_rate = baud_rate;
 356
 357         if (baud_rate) {
 358                 spin_lock_irqsave(&priv->lock, flags);
 359                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 360                 spin_unlock_irqrestore(&priv->lock, flags);
 361                 ch341_set_baudrate(port->serial->dev, priv);
 362         } else {
 363                 spin_lock_irqsave(&priv->lock, flags);
 364                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 365                 spin_unlock_irqrestore(&priv->lock, flags);
 366         }
 367
 368         ch341_set_handshake(port->serial->dev, priv->line_control);
 369
 370         /* Unimplemented:
 371          * (cflag & CSIZE) : data bits [5, 8]
 372          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 373          * (cflag & CSTOPB) : stop bits [1, 2]
 374          */
 375 }
 376
 377 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 378 {
 379         const uint16_t ch341_break_reg =
 380                 CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
 381         struct usb_serial_port *port = tty->driver_data;
 382         int r;
 383         uint16_t reg_contents;
 384         uint8_t *break_reg;
 385
 386         break_reg = kmalloc(2, GFP_KERNEL);
 387         if (!break_reg) {
 388                 dev_err(&port->dev, "%s - kmalloc failed\n", __func__);
 389                 return;
 390         }
 391
 392         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 393                         ch341_break_reg, 0, break_reg, 2);
 394         if (r < 0) {
 395                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 396                                 __func__, r);
 397                 goto out;
 398         }
 399         dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 400                 __func__, break_reg[0], break_reg[1]);
 401         if (break_state != 0) {
 402                 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 403                 break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
 404                 break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
 405         } else {
 406                 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 407                 break_reg[0] |= CH341_NBREAK_BITS_REG1;
 408                 break_reg[1] |= CH341_NBREAK_BITS_REG2;
 409         }
 410         dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 411                 __func__, break_reg[0], break_reg[1]);
 412         reg_contents = get_unaligned_le16(break_reg);
 413         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 414                         ch341_break_reg, reg_contents);
 415         if (r < 0)
 416                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 417                                 __func__, r);
 418 out:
 419         kfree(break_reg);
 420 }
 421
 422 static int ch341_tiocmset(struct tty_struct *tty,
 423                           unsigned int set, unsigned int clear)
 424 {
 425         struct usb_serial_port *port = tty->driver_data;
 426         struct ch341_private *priv = usb_get_serial_port_data(port);
 427         unsigned long flags;
 428         u8 control;
 429
 430         spin_lock_irqsave(&priv->lock, flags);
 431         if (set & TIOCM_RTS)
 432                 priv->line_control |= CH341_BIT_RTS;
 433         if (set & TIOCM_DTR)
 434                 priv->line_control |= CH341_BIT_DTR;
 435         if (clear & TIOCM_RTS)
 436                 priv->line_control &= ~CH341_BIT_RTS;
 437         if (clear & TIOCM_DTR)
 438                 priv->line_control &= ~CH341_BIT_DTR;
 439         control = priv->line_control;
 440         spin_unlock_irqrestore(&priv->lock, flags);
 441
 442         return ch341_set_handshake(port->serial->dev, control);
 443 }
 444
 445 static void ch341_read_int_callback(struct urb *urb)
 446 {
 447         struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
 448         unsigned char *data = urb->transfer_buffer;
 449         unsigned int actual_length = urb->actual_length;
 450         int status;
 451
 452         switch (urb->status) {
 453         case 0:
 454                 /* success */
 455                 break;
 456         case -ECONNRESET:
 457         case -ENOENT:
 458         case -ESHUTDOWN:
 459                 /* this urb is terminated, clean up */
 460                 dev_dbg(&urb->dev->dev, "%s - urb shutting down with status: %d\n",
 461                         __func__, urb->status);
 462                 return;
 463         default:
 464                 dev_dbg(&urb->dev->dev, "%s - nonzero urb status received: %d\n",
 465                         __func__, urb->status);
 466                 goto exit;
 467         }
 468
 469         usb_serial_debug_data(&port->dev, __func__,
 470                               urb->actual_length, urb->transfer_buffer);
 471
 472         if (actual_length >= 4) {
 473                 struct ch341_private *priv = usb_get_serial_port_data(port);
 474                 unsigned long flags;
 475                 u8 prev_line_status = priv->line_status;
 476
 477                 spin_lock_irqsave(&priv->lock, flags);
 478                 priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
 479                 if ((data[1] & CH341_MULT_STAT))
 480                         priv->multi_status_change = 1;
 481                 spin_unlock_irqrestore(&priv->lock, flags);
 482
 483                 if ((priv->line_status ^ prev_line_status) & CH341_BIT_DCD) {
 484                         struct tty_struct *tty = tty_port_tty_get(&port->port);
 485                         if (tty)
 486                                 usb_serial_handle_dcd_change(port, tty,
 487                                             priv->line_status & CH341_BIT_DCD);
 488                         tty_kref_put(tty);
 489                 }
 490
 491                 wake_up_interruptible(&port->port.delta_msr_wait);
 492         }
 493
 494 exit:
 495         status = usb_submit_urb(urb, GFP_ATOMIC);
 496         if (status)
 497                 dev_err(&urb->dev->dev,
 498                         "%s - usb_submit_urb failed with result %d\n",
 499                         __func__, status);
 500 }
 501
 502 static int ch341_tiocmiwait(struct tty_struct *tty, unsigned long arg)
 503 {
 504         struct usb_serial_port *port = tty->driver_data;
 505         struct ch341_private *priv = usb_get_serial_port_data(port);
 506         unsigned long flags;
 507         u8 prevstatus;
 508         u8 status;
 509         u8 changed;
 510         u8 multi_change = 0;
 511
 512         spin_lock_irqsave(&priv->lock, flags);
 513         prevstatus = priv->line_status;
 514         priv->multi_status_change = 0;
 515         spin_unlock_irqrestore(&priv->lock, flags);
 516
 517         while (!multi_change) {
 518                 interruptible_sleep_on(&port->port.delta_msr_wait);
 519                 /* see if a signal did it */
 520                 if (signal_pending(current))
 521                         return -ERESTARTSYS;
 522
 523                 if (port->serial->disconnected)
 524                         return -EIO;
 525
 526                 spin_lock_irqsave(&priv->lock, flags);
 527                 status = priv->line_status;
 528                 multi_change = priv->multi_status_change;
 529                 spin_unlock_irqrestore(&priv->lock, flags);
 530
 531                 changed = prevstatus ^ status;
 532
 533                 if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
 534                     ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
 535                     ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
 536                     ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
 537                         return 0;
 538                 }
 539                 prevstatus = status;
 540         }
 541
 542         return 0;
 543 }
 544
 545 static int ch341_tiocmget(struct tty_struct *tty)
 546 {
 547         struct usb_serial_port *port = tty->driver_data;
 548         struct ch341_private *priv = usb_get_serial_port_data(port);
 549         unsigned long flags;
 550         u8 mcr;
 551         u8 status;
 552         unsigned int result;
 553
 554         spin_lock_irqsave(&priv->lock, flags);
 555         mcr = priv->line_control;
 556         status = priv->line_status;
 557         spin_unlock_irqrestore(&priv->lock, flags);
 558
 559         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 560                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 561                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 562                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 563                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 564                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 565
 566         dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 567
 568         return result;
 569 }
 570
 571 static int ch341_reset_resume(struct usb_serial *serial)
 572 {
 573         struct ch341_private *priv;
 574
 575         priv = usb_get_serial_port_data(serial->port[0]);
 576
 577         /* reconfigure ch341 serial port after bus-reset */
 578         ch341_configure(serial->dev, priv);
 579
 580         return 0;
 581 }
 582
 583 static struct usb_serial_driver ch341_device = {
 584         .driver = {
 585                 .owner  = THIS_MODULE,
 586                 .name   = "ch341-uart",
 587         },
 588         .id_table          = id_table,
 589         .num_ports         = 1,
 590         .open              = ch341_open,
 591         .dtr_rts           = ch341_dtr_rts,
 592         .carrier_raised    = ch341_carrier_raised,
 593         .close             = ch341_close,
 594         .set_termios       = ch341_set_termios,
 595         .break_ctl         = ch341_break_ctl,
 596         .tiocmget          = ch341_tiocmget,
 597         .tiocmset          = ch341_tiocmset,
 598         .tiocmiwait        = ch341_tiocmiwait,
 599         .read_int_callback = ch341_read_int_callback,
 600         .port_probe        = ch341_port_probe,
 601         .port_remove       = ch341_port_remove,
 602         .reset_resume      = ch341_reset_resume,
 603 };
 604
 605 static struct usb_serial_driver * const serial_drivers[] = {
 606         &ch341_device, NULL
 607 };
 608
 609 module_usb_serial_driver(serial_drivers, id_table);
 610
 611 MODULE_LICENSE("GPL");