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
 262         r = ch341_configure(port->serial->dev, priv);
 263         if (r < 0)
 264                 goto error;
 265
 266         usb_set_serial_port_data(port, priv);
 267         return 0;
 268
 269 error:  kfree(priv);
 270         return r;
 271 }
 272
 273 static int ch341_port_remove(struct usb_serial_port *port)
 274 {
 275         struct ch341_private *priv;
 276
 277         priv = usb_get_serial_port_data(port);
 278         kfree(priv);
 279
 280         return 0;
 281 }
 282
 283 static int ch341_carrier_raised(struct usb_serial_port *port)
 284 {
 285         struct ch341_private *priv = usb_get_serial_port_data(port);
 286         if (priv->line_status & CH341_BIT_DCD)
 287                 return 1;
 288         return 0;
 289 }
 290
 291 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 292 {
 293         struct ch341_private *priv = usb_get_serial_port_data(port);
 294         unsigned long flags;
 295
 296         /* drop DTR and RTS */
 297         spin_lock_irqsave(&priv->lock, flags);
 298         if (on)
 299                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 300         else
 301                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 302         spin_unlock_irqrestore(&priv->lock, flags);
 303         ch341_set_handshake(port->serial->dev, priv->line_control);
 304 }
 305
 306 static void ch341_close(struct usb_serial_port *port)
 307 {
 308         usb_serial_generic_close(port);
 309         usb_kill_urb(port->interrupt_in_urb);
 310 }
 311
 312
 313 /* open this device, set default parameters */
 314 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 315 {
 316         struct usb_serial *serial = port->serial;
 317         struct ch341_private *priv = usb_get_serial_port_data(port);
 318         int r;
 319
 320         r = ch341_configure(serial->dev, priv);
 321         if (r)
 322                 goto out;
 323
 324         if (tty)
 325                 ch341_set_termios(tty, port, NULL);
 326
 327         dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
 328         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 329         if (r) {
 330                 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
 331                         __func__, r);
 332                 goto out;
 333         }
 334
 335         r = usb_serial_generic_open(tty, port);
 336
 337 out:    return r;
 338 }
 339
 340 /* Old_termios contains the original termios settings and
 341  * tty->termios contains the new setting to be used.
 342  */
 343 static void ch341_set_termios(struct tty_struct *tty,
 344                 struct usb_serial_port *port, struct ktermios *old_termios)
 345 {
 346         struct ch341_private *priv = usb_get_serial_port_data(port);
 347         unsigned baud_rate;
 348         unsigned long flags;
 349         unsigned char ctrl;
 350         int r;
 351
 352         /* redundant changes may cause the chip to lose bytes */
 353         if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 354                 return;
 355
 356         baud_rate = tty_get_baud_rate(tty);
 357
 358         priv->baud_rate = baud_rate;
 359         ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 360
 361         switch (C_CSIZE(tty)) {
 362         case CS5:
 363                 ctrl |= CH341_LCR_CS5;
 364                 break;
 365         case CS6:
 366                 ctrl |= CH341_LCR_CS6;
 367                 break;
 368         case CS7:
 369                 ctrl |= CH341_LCR_CS7;
 370                 break;
 371         case CS8:
 372                 ctrl |= CH341_LCR_CS8;
 373                 break;
 374         }
 375
 376         if (C_PARENB(tty)) {
 377                 ctrl |= CH341_LCR_ENABLE_PAR;
 378                 if (C_PARODD(tty) == 0)
 379                         ctrl |= CH341_LCR_PAR_EVEN;
 380                 if (C_CMSPAR(tty))
 381                         ctrl |= CH341_LCR_MARK_SPACE;
 382         }
 383
 384         if (C_CSTOPB(tty))
 385                 ctrl |= CH341_LCR_STOP_BITS_2;
 386
 387         if (baud_rate) {
 388                 spin_lock_irqsave(&priv->lock, flags);
 389                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 390                 spin_unlock_irqrestore(&priv->lock, flags);
 391                 r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
 392                 if (r < 0 && old_termios) {
 393                         priv->baud_rate = tty_termios_baud_rate(old_termios);
 394                         tty_termios_copy_hw(&tty->termios, old_termios);
 395                 }
 396         } else {
 397                 spin_lock_irqsave(&priv->lock, flags);
 398                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 399                 spin_unlock_irqrestore(&priv->lock, flags);
 400         }
 401
 402         ch341_set_handshake(port->serial->dev, priv->line_control);
 403
 404 }
 405
 406 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 407 {
 408         const uint16_t ch341_break_reg =
 409                         ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 410         struct usb_serial_port *port = tty->driver_data;
 411         int r;
 412         uint16_t reg_contents;
 413         uint8_t *break_reg;
 414
 415         break_reg = kmalloc(2, GFP_KERNEL);
 416         if (!break_reg)
 417                 return;
 418
 419         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 420                         ch341_break_reg, 0, break_reg, 2);
 421         if (r < 0) {
 422                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 423                                 __func__, r);
 424                 goto out;
 425         }
 426         dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 427                 __func__, break_reg[0], break_reg[1]);
 428         if (break_state != 0) {
 429                 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 430                 break_reg[0] &= ~CH341_NBREAK_BITS;
 431                 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 432         } else {
 433                 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 434                 break_reg[0] |= CH341_NBREAK_BITS;
 435                 break_reg[1] |= CH341_LCR_ENABLE_TX;
 436         }
 437         dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 438                 __func__, break_reg[0], break_reg[1]);
 439         reg_contents = get_unaligned_le16(break_reg);
 440         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 441                         ch341_break_reg, reg_contents);
 442         if (r < 0)
 443                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 444                                 __func__, r);
 445 out:
 446         kfree(break_reg);
 447 }
 448
 449 static int ch341_tiocmset(struct tty_struct *tty,
 450                           unsigned int set, unsigned int clear)
 451 {
 452         struct usb_serial_port *port = tty->driver_data;
 453         struct ch341_private *priv = usb_get_serial_port_data(port);
 454         unsigned long flags;
 455         u8 control;
 456
 457         spin_lock_irqsave(&priv->lock, flags);
 458         if (set & TIOCM_RTS)
 459                 priv->line_control |= CH341_BIT_RTS;
 460         if (set & TIOCM_DTR)
 461                 priv->line_control |= CH341_BIT_DTR;
 462         if (clear & TIOCM_RTS)
 463                 priv->line_control &= ~CH341_BIT_RTS;
 464         if (clear & TIOCM_DTR)
 465                 priv->line_control &= ~CH341_BIT_DTR;
 466         control = priv->line_control;
 467         spin_unlock_irqrestore(&priv->lock, flags);
 468
 469         return ch341_set_handshake(port->serial->dev, control);
 470 }
 471
 472 static void ch341_update_line_status(struct usb_serial_port *port,
 473                                         unsigned char *data, size_t len)
 474 {
 475         struct ch341_private *priv = usb_get_serial_port_data(port);
 476         struct tty_struct *tty;
 477         unsigned long flags;
 478         u8 status;
 479         u8 delta;
 480
 481         if (len < 4)
 482                 return;
 483
 484         status = ~data[2] & CH341_BITS_MODEM_STAT;
 485
 486         spin_lock_irqsave(&priv->lock, flags);
 487         delta = status ^ priv->line_status;
 488         priv->line_status = status;
 489         spin_unlock_irqrestore(&priv->lock, flags);
 490
 491         if (data[1] & CH341_MULT_STAT)
 492                 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
 493
 494         if (!delta)
 495                 return;
 496
 497         if (delta & CH341_BIT_CTS)
 498                 port->icount.cts++;
 499         if (delta & CH341_BIT_DSR)
 500                 port->icount.dsr++;
 501         if (delta & CH341_BIT_RI)
 502                 port->icount.rng++;
 503         if (delta & CH341_BIT_DCD) {
 504                 port->icount.dcd++;
 505                 tty = tty_port_tty_get(&port->port);
 506                 if (tty) {
 507                         usb_serial_handle_dcd_change(port, tty,
 508                                                 status & CH341_BIT_DCD);
 509                         tty_kref_put(tty);
 510                 }
 511         }
 512
 513         wake_up_interruptible(&port->port.delta_msr_wait);
 514 }
 515
 516 static void ch341_read_int_callback(struct urb *urb)
 517 {
 518         struct usb_serial_port *port = urb->context;
 519         unsigned char *data = urb->transfer_buffer;
 520         unsigned int len = urb->actual_length;
 521         int status;
 522
 523         switch (urb->status) {
 524         case 0:
 525                 /* success */
 526                 break;
 527         case -ECONNRESET:
 528         case -ENOENT:
 529         case -ESHUTDOWN:
 530                 /* this urb is terminated, clean up */
 531                 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
 532                         __func__, urb->status);
 533                 return;
 534         default:
 535                 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
 536                         __func__, urb->status);
 537                 goto exit;
 538         }
 539
 540         usb_serial_debug_data(&port->dev, __func__, len, data);
 541         ch341_update_line_status(port, data, len);
 542 exit:
 543         status = usb_submit_urb(urb, GFP_ATOMIC);
 544         if (status) {
 545                 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
 546                         __func__, status);
 547         }
 548 }
 549
 550 static int ch341_tiocmget(struct tty_struct *tty)
 551 {
 552         struct usb_serial_port *port = tty->driver_data;
 553         struct ch341_private *priv = usb_get_serial_port_data(port);
 554         unsigned long flags;
 555         u8 mcr;
 556         u8 status;
 557         unsigned int result;
 558
 559         spin_lock_irqsave(&priv->lock, flags);
 560         mcr = priv->line_control;
 561         status = priv->line_status;
 562         spin_unlock_irqrestore(&priv->lock, flags);
 563
 564         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 565                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 566                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 567                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 568                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 569                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 570
 571         dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 572
 573         return result;
 574 }
 575
 576 static int ch341_reset_resume(struct usb_serial *serial)
 577 {
 578         struct ch341_private *priv;
 579
 580         priv = usb_get_serial_port_data(serial->port[0]);
 581
 582         /* reconfigure ch341 serial port after bus-reset */
 583         ch341_configure(serial->dev, priv);
 584
 585         return 0;
 586 }
 587
 588 static struct usb_serial_driver ch341_device = {
 589         .driver = {
 590                 .owner  = THIS_MODULE,
 591                 .name   = "ch341-uart",
 592         },
 593         .id_table          = id_table,
 594         .num_ports         = 1,
 595         .open              = ch341_open,
 596         .dtr_rts           = ch341_dtr_rts,
 597         .carrier_raised    = ch341_carrier_raised,
 598         .close             = ch341_close,
 599         .set_termios       = ch341_set_termios,
 600         .break_ctl         = ch341_break_ctl,
 601         .tiocmget          = ch341_tiocmget,
 602         .tiocmset          = ch341_tiocmset,
 603         .tiocmiwait        = usb_serial_generic_tiocmiwait,
 604         .read_int_callback = ch341_read_int_callback,
 605         .port_probe        = ch341_port_probe,
 606         .port_remove       = ch341_port_remove,
 607         .reset_resume      = ch341_reset_resume,
 608 };
 609
 610 static struct usb_serial_driver * const serial_drivers[] = {
 611         &ch341_device, NULL
 612 };
 613
 614 module_usb_serial_driver(serial_drivers, id_table);
 615
 616 MODULE_LICENSE("GPL");