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 };
  99
 100 static void ch341_set_termios(struct tty_struct *tty,
 101                               struct usb_serial_port *port,
 102                               struct ktermios *old_termios);
 103
 104 static int ch341_control_out(struct usb_device *dev, u8 request,
 105                              u16 value, u16 index)
 106 {
 107         int r;
 108
 109         dev_dbg(&dev->dev, "ch341_control_out(%02x,%02x,%04x,%04x)\n",
 110                 USB_DIR_OUT|0x40, (int)request, (int)value, (int)index);
 111
 112         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 113                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 114                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 115
 116         return r;
 117 }
 118
 119 static int ch341_control_in(struct usb_device *dev,
 120                             u8 request, u16 value, u16 index,
 121                             char *buf, unsigned bufsize)
 122 {
 123         int r;
 124
 125         dev_dbg(&dev->dev, "ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)\n",
 126                 USB_DIR_IN|0x40, (int)request, (int)value, (int)index, buf,
 127                 (int)bufsize);
 128
 129         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 130                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 131                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 132         return r;
 133 }
 134
 135 static int ch341_init_set_baudrate(struct usb_device *dev,
 136                                    struct ch341_private *priv, unsigned ctrl)
 137 {
 138         short a;
 139         int r;
 140         unsigned long factor;
 141         short divisor;
 142
 143         if (!priv->baud_rate)
 144                 return -EINVAL;
 145         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 146         divisor = CH341_BAUDBASE_DIVMAX;
 147
 148         while ((factor > 0xfff0) && divisor) {
 149                 factor >>= 3;
 150                 divisor--;
 151         }
 152
 153         if (factor > 0xfff0)
 154                 return -EINVAL;
 155
 156         factor = 0x10000 - factor;
 157         a = (factor & 0xff00) | divisor;
 158
 159         /* 0x9c is "enable SFR_UART Control register and timer" */
 160         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT,
 161                               0x9c | (ctrl << 8), a | 0x80);
 162
 163         return r;
 164 }
 165
 166 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 167 {
 168         return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
 169 }
 170
 171 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 172 {
 173         char *buffer;
 174         int r;
 175         const unsigned size = 8;
 176         unsigned long flags;
 177
 178         buffer = kmalloc(size, GFP_KERNEL);
 179         if (!buffer)
 180                 return -ENOMEM;
 181
 182         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
 183         if (r < 0)
 184                 goto out;
 185
 186         /* setup the private status if available */
 187         if (r == 2) {
 188                 r = 0;
 189                 spin_lock_irqsave(&priv->lock, flags);
 190                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 191                 spin_unlock_irqrestore(&priv->lock, flags);
 192         } else
 193                 r = -EPROTO;
 194
 195 out:    kfree(buffer);
 196         return r;
 197 }
 198
 199 /* -------------------------------------------------------------------------- */
 200
 201 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 202 {
 203         char *buffer;
 204         int r;
 205         const unsigned size = 8;
 206
 207         buffer = kmalloc(size, GFP_KERNEL);
 208         if (!buffer)
 209                 return -ENOMEM;
 210
 211         /* expect two bytes 0x27 0x00 */
 212         r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
 213         if (r < 0)
 214                 goto out;
 215         dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
 216
 217         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
 218         if (r < 0)
 219                 goto out;
 220
 221         /* expect two bytes 0x56 0x00 */
 222         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size);
 223         if (r < 0)
 224                 goto out;
 225
 226         r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, 0x0050);
 227         if (r < 0)
 228                 goto out;
 229
 230         /* expect 0xff 0xee */
 231         r = ch341_get_status(dev, priv);
 232         if (r < 0)
 233                 goto out;
 234
 235         r = ch341_init_set_baudrate(dev, priv, 0);
 236         if (r < 0)
 237                 goto out;
 238
 239         r = ch341_set_handshake(dev, priv->line_control);
 240         if (r < 0)
 241                 goto out;
 242
 243         /* expect 0x9f 0xee */
 244         r = ch341_get_status(dev, priv);
 245
 246 out:    kfree(buffer);
 247         return r;
 248 }
 249
 250 static int ch341_port_probe(struct usb_serial_port *port)
 251 {
 252         struct ch341_private *priv;
 253         int r;
 254
 255         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 256         if (!priv)
 257                 return -ENOMEM;
 258
 259         spin_lock_init(&priv->lock);
 260         priv->baud_rate = DEFAULT_BAUD_RATE;
 261         priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 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                 goto out;
 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                 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         unsigned char ctrl;
 351         int r;
 352
 353         /* redundant changes may cause the chip to lose bytes */
 354         if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 355                 return;
 356
 357         baud_rate = tty_get_baud_rate(tty);
 358
 359         priv->baud_rate = baud_rate;
 360         ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 361
 362         switch (C_CSIZE(tty)) {
 363         case CS5:
 364                 ctrl |= CH341_LCR_CS5;
 365                 break;
 366         case CS6:
 367                 ctrl |= CH341_LCR_CS6;
 368                 break;
 369         case CS7:
 370                 ctrl |= CH341_LCR_CS7;
 371                 break;
 372         case CS8:
 373                 ctrl |= CH341_LCR_CS8;
 374                 break;
 375         }
 376
 377         if (C_PARENB(tty)) {
 378                 ctrl |= CH341_LCR_ENABLE_PAR;
 379                 if (C_PARODD(tty) == 0)
 380                         ctrl |= CH341_LCR_PAR_EVEN;
 381                 if (C_CMSPAR(tty))
 382                         ctrl |= CH341_LCR_MARK_SPACE;
 383         }
 384
 385         if (C_CSTOPB(tty))
 386                 ctrl |= CH341_LCR_STOP_BITS_2;
 387
 388         if (baud_rate) {
 389                 spin_lock_irqsave(&priv->lock, flags);
 390                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 391                 spin_unlock_irqrestore(&priv->lock, flags);
 392                 r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
 393                 if (r < 0 && old_termios) {
 394                         priv->baud_rate = tty_termios_baud_rate(old_termios);
 395                         tty_termios_copy_hw(&tty->termios, old_termios);
 396                 }
 397         } else {
 398                 spin_lock_irqsave(&priv->lock, flags);
 399                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 400                 spin_unlock_irqrestore(&priv->lock, flags);
 401         }
 402
 403         ch341_set_handshake(port->serial->dev, priv->line_control);
 404
 405 }
 406
 407 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 408 {
 409         const uint16_t ch341_break_reg =
 410                         ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 411         struct usb_serial_port *port = tty->driver_data;
 412         int r;
 413         uint16_t reg_contents;
 414         uint8_t *break_reg;
 415
 416         break_reg = kmalloc(2, GFP_KERNEL);
 417         if (!break_reg)
 418                 return;
 419
 420         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 421                         ch341_break_reg, 0, break_reg, 2);
 422         if (r < 0) {
 423                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 424                                 __func__, r);
 425                 goto out;
 426         }
 427         dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 428                 __func__, break_reg[0], break_reg[1]);
 429         if (break_state != 0) {
 430                 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 431                 break_reg[0] &= ~CH341_NBREAK_BITS;
 432                 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 433         } else {
 434                 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 435                 break_reg[0] |= CH341_NBREAK_BITS;
 436                 break_reg[1] |= CH341_LCR_ENABLE_TX;
 437         }
 438         dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 439                 __func__, break_reg[0], break_reg[1]);
 440         reg_contents = get_unaligned_le16(break_reg);
 441         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 442                         ch341_break_reg, reg_contents);
 443         if (r < 0)
 444                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 445                                 __func__, r);
 446 out:
 447         kfree(break_reg);
 448 }
 449
 450 static int ch341_tiocmset(struct tty_struct *tty,
 451                           unsigned int set, unsigned int clear)
 452 {
 453         struct usb_serial_port *port = tty->driver_data;
 454         struct ch341_private *priv = usb_get_serial_port_data(port);
 455         unsigned long flags;
 456         u8 control;
 457
 458         spin_lock_irqsave(&priv->lock, flags);
 459         if (set & TIOCM_RTS)
 460                 priv->line_control |= CH341_BIT_RTS;
 461         if (set & TIOCM_DTR)
 462                 priv->line_control |= CH341_BIT_DTR;
 463         if (clear & TIOCM_RTS)
 464                 priv->line_control &= ~CH341_BIT_RTS;
 465         if (clear & TIOCM_DTR)
 466                 priv->line_control &= ~CH341_BIT_DTR;
 467         control = priv->line_control;
 468         spin_unlock_irqrestore(&priv->lock, flags);
 469
 470         return ch341_set_handshake(port->serial->dev, control);
 471 }
 472
 473 static void ch341_update_line_status(struct usb_serial_port *port,
 474                                         unsigned char *data, size_t len)
 475 {
 476         struct ch341_private *priv = usb_get_serial_port_data(port);
 477         struct tty_struct *tty;
 478         unsigned long flags;
 479         u8 status;
 480         u8 delta;
 481
 482         if (len < 4)
 483                 return;
 484
 485         status = ~data[2] & CH341_BITS_MODEM_STAT;
 486
 487         spin_lock_irqsave(&priv->lock, flags);
 488         delta = status ^ priv->line_status;
 489         priv->line_status = status;
 490         spin_unlock_irqrestore(&priv->lock, flags);
 491
 492         if (data[1] & CH341_MULT_STAT)
 493                 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
 494
 495         if (!delta)
 496                 return;
 497
 498         if (delta & CH341_BIT_CTS)
 499                 port->icount.cts++;
 500         if (delta & CH341_BIT_DSR)
 501                 port->icount.dsr++;
 502         if (delta & CH341_BIT_RI)
 503                 port->icount.rng++;
 504         if (delta & CH341_BIT_DCD) {
 505                 port->icount.dcd++;
 506                 tty = tty_port_tty_get(&port->port);
 507                 if (tty) {
 508                         usb_serial_handle_dcd_change(port, tty,
 509                                                 status & CH341_BIT_DCD);
 510                         tty_kref_put(tty);
 511                 }
 512         }
 513
 514         wake_up_interruptible(&port->port.delta_msr_wait);
 515 }
 516
 517 static void ch341_read_int_callback(struct urb *urb)
 518 {
 519         struct usb_serial_port *port = urb->context;
 520         unsigned char *data = urb->transfer_buffer;
 521         unsigned int len = urb->actual_length;
 522         int status;
 523
 524         switch (urb->status) {
 525         case 0:
 526                 /* success */
 527                 break;
 528         case -ECONNRESET:
 529         case -ENOENT:
 530         case -ESHUTDOWN:
 531                 /* this urb is terminated, clean up */
 532                 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
 533                         __func__, urb->status);
 534                 return;
 535         default:
 536                 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
 537                         __func__, urb->status);
 538                 goto exit;
 539         }
 540
 541         usb_serial_debug_data(&port->dev, __func__, len, data);
 542         ch341_update_line_status(port, data, len);
 543 exit:
 544         status = usb_submit_urb(urb, GFP_ATOMIC);
 545         if (status) {
 546                 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
 547                         __func__, status);
 548         }
 549 }
 550
 551 static int ch341_tiocmget(struct tty_struct *tty)
 552 {
 553         struct usb_serial_port *port = tty->driver_data;
 554         struct ch341_private *priv = usb_get_serial_port_data(port);
 555         unsigned long flags;
 556         u8 mcr;
 557         u8 status;
 558         unsigned int result;
 559
 560         spin_lock_irqsave(&priv->lock, flags);
 561         mcr = priv->line_control;
 562         status = priv->line_status;
 563         spin_unlock_irqrestore(&priv->lock, flags);
 564
 565         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 566                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 567                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 568                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 569                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 570                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 571
 572         dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 573
 574         return result;
 575 }
 576
 577 static int ch341_reset_resume(struct usb_serial *serial)
 578 {
 579         struct ch341_private *priv;
 580
 581         priv = usb_get_serial_port_data(serial->port[0]);
 582
 583         /* reconfigure ch341 serial port after bus-reset */
 584         ch341_configure(serial->dev, priv);
 585
 586         return 0;
 587 }
 588
 589 static struct usb_serial_driver ch341_device = {
 590         .driver = {
 591                 .owner  = THIS_MODULE,
 592                 .name   = "ch341-uart",
 593         },
 594         .id_table          = id_table,
 595         .num_ports         = 1,
 596         .open              = ch341_open,
 597         .dtr_rts           = ch341_dtr_rts,
 598         .carrier_raised    = ch341_carrier_raised,
 599         .close             = ch341_close,
 600         .set_termios       = ch341_set_termios,
 601         .break_ctl         = ch341_break_ctl,
 602         .tiocmget          = ch341_tiocmget,
 603         .tiocmset          = ch341_tiocmset,
 604         .tiocmiwait        = usb_serial_generic_tiocmiwait,
 605         .read_int_callback = ch341_read_int_callback,
 606         .port_probe        = ch341_port_probe,
 607         .port_remove       = ch341_port_remove,
 608         .reset_resume      = ch341_reset_resume,
 609 };
 610
 611 static struct usb_serial_driver * const serial_drivers[] = {
 612         &ch341_device, NULL
 613 };
 614
 615 module_usb_serial_driver(serial_drivers, id_table);
 616
 617 MODULE_LICENSE("GPL");