linux/drivers/usb/serial/ch341.c
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   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
  72static const struct usb_device_id id_table[] = {
  73        { USB_DEVICE(0x4348, 0x5523) },
  74        { USB_DEVICE(0x1a86, 0x7523) },
  75        { USB_DEVICE(0x1a86, 0x5523) },
  76        { },
  77};
  78MODULE_DEVICE_TABLE(usb, id_table);
  79
  80struct 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
  87static void ch341_set_termios(struct tty_struct *tty,
  88                              struct usb_serial_port *port,
  89                              struct ktermios *old_termios);
  90
  91static 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
 106static 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
 122static 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
 154static int ch341_set_handshake(struct usb_device *dev, u8 control)
 155{
 156        return ch341_control_out(dev, 0xa4, ~control, 0);
 157}
 158
 159static 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
 183out:    kfree(buffer);
 184        return r;
 185}
 186
 187/* -------------------------------------------------------------------------- */
 188
 189static 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
 241out:    kfree(buffer);
 242        return r;
 243}
 244
 245static 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
 265error:  kfree(priv);
 266        return r;
 267}
 268
 269static 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
 279static 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
 287static 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
 302static 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 */
 310static 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
 333out:    return r;
 334}
 335
 336/* Old_termios contains the original termios settings and
 337 * tty->termios contains the new setting to be used.
 338 */
 339static 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
 370static 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);
 409out:
 410        kfree(break_reg);
 411}
 412
 413static 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
 436static 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
 480static 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);
 506exit:
 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
 514static 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
 540static 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
 552static 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
 574static struct usb_serial_driver * const serial_drivers[] = {
 575        &ch341_device, NULL
 576};
 577
 578module_usb_serial_driver(serial_drivers, id_table);
 579
 580MODULE_LICENSE("GPL");
 581