linux/drivers/usb/serial/ch341.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
   4 * Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
   5 * Copyright 2009, Boris Hajduk <boris@hajduk.org>
   6 *
   7 * ch341.c implements a serial port driver for the Winchiphead CH341.
   8 *
   9 * The CH341 device can be used to implement an RS232 asynchronous
  10 * serial port, an IEEE-1284 parallel printer port or a memory-like
  11 * interface. In all cases the CH341 supports an I2C interface as well.
  12 * This driver only supports the asynchronous serial interface.
  13 */
  14
  15#include <linux/kernel.h>
  16#include <linux/tty.h>
  17#include <linux/module.h>
  18#include <linux/slab.h>
  19#include <linux/usb.h>
  20#include <linux/usb/serial.h>
  21#include <linux/serial.h>
  22#include <asm/unaligned.h>
  23
  24#define DEFAULT_BAUD_RATE 9600
  25#define DEFAULT_TIMEOUT   1000
  26
  27/* flags for IO-Bits */
  28#define CH341_BIT_RTS (1 << 6)
  29#define CH341_BIT_DTR (1 << 5)
  30
  31/******************************/
  32/* interrupt pipe definitions */
  33/******************************/
  34/* always 4 interrupt bytes */
  35/* first irq byte normally 0x08 */
  36/* second irq byte base 0x7d + below */
  37/* third irq byte base 0x94 + below */
  38/* fourth irq byte normally 0xee */
  39
  40/* second interrupt byte */
  41#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
  42
  43/* status returned in third interrupt answer byte, inverted in data
  44   from irq */
  45#define CH341_BIT_CTS 0x01
  46#define CH341_BIT_DSR 0x02
  47#define CH341_BIT_RI  0x04
  48#define CH341_BIT_DCD 0x08
  49#define CH341_BITS_MODEM_STAT 0x0f /* all bits */
  50
  51/*******************************/
  52/* baudrate calculation factor */
  53/*******************************/
  54#define CH341_BAUDBASE_FACTOR 1532620800
  55#define CH341_BAUDBASE_DIVMAX 3
  56
  57/* Break support - the information used to implement this was gleaned from
  58 * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  59 */
  60
  61#define CH341_REQ_READ_VERSION 0x5F
  62#define CH341_REQ_WRITE_REG    0x9A
  63#define CH341_REQ_READ_REG     0x95
  64#define CH341_REQ_SERIAL_INIT  0xA1
  65#define CH341_REQ_MODEM_CTRL   0xA4
  66
  67#define CH341_REG_BREAK        0x05
  68#define CH341_REG_LCR          0x18
  69#define CH341_NBREAK_BITS      0x01
  70
  71#define CH341_LCR_ENABLE_RX    0x80
  72#define CH341_LCR_ENABLE_TX    0x40
  73#define CH341_LCR_MARK_SPACE   0x20
  74#define CH341_LCR_PAR_EVEN     0x10
  75#define CH341_LCR_ENABLE_PAR   0x08
  76#define CH341_LCR_STOP_BITS_2  0x04
  77#define CH341_LCR_CS8          0x03
  78#define CH341_LCR_CS7          0x02
  79#define CH341_LCR_CS6          0x01
  80#define CH341_LCR_CS5          0x00
  81
  82static const struct usb_device_id id_table[] = {
  83        { USB_DEVICE(0x4348, 0x5523) },
  84        { USB_DEVICE(0x1a86, 0x7523) },
  85        { USB_DEVICE(0x1a86, 0x5523) },
  86        { },
  87};
  88MODULE_DEVICE_TABLE(usb, id_table);
  89
  90struct ch341_private {
  91        spinlock_t lock; /* access lock */
  92        unsigned baud_rate; /* set baud rate */
  93        u8 mcr;
  94        u8 msr;
  95        u8 lcr;
  96};
  97
  98static void ch341_set_termios(struct tty_struct *tty,
  99                              struct usb_serial_port *port,
 100                              struct ktermios *old_termios);
 101
 102static int ch341_control_out(struct usb_device *dev, u8 request,
 103                             u16 value, u16 index)
 104{
 105        int r;
 106
 107        dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
 108                request, value, index);
 109
 110        r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 111                            USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 112                            value, index, NULL, 0, DEFAULT_TIMEOUT);
 113        if (r < 0)
 114                dev_err(&dev->dev, "failed to send control message: %d\n", r);
 115
 116        return r;
 117}
 118
 119static 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, "%s - (%02x,%04x,%04x,%u)\n", __func__,
 126                request, value, index, bufsize);
 127
 128        r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 129                            USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 130                            value, index, buf, bufsize, DEFAULT_TIMEOUT);
 131        if (r < (int)bufsize) {
 132                if (r >= 0) {
 133                        dev_err(&dev->dev,
 134                                "short control message received (%d < %u)\n",
 135                                r, bufsize);
 136                        r = -EIO;
 137                }
 138
 139                dev_err(&dev->dev, "failed to receive control message: %d\n",
 140                        r);
 141                return r;
 142        }
 143
 144        return 0;
 145}
 146
 147static int ch341_set_baudrate_lcr(struct usb_device *dev,
 148                                  struct ch341_private *priv, u8 lcr)
 149{
 150        short a;
 151        int r;
 152        unsigned long factor;
 153        short divisor;
 154
 155        if (!priv->baud_rate)
 156                return -EINVAL;
 157        factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 158        divisor = CH341_BAUDBASE_DIVMAX;
 159
 160        while ((factor > 0xfff0) && divisor) {
 161                factor >>= 3;
 162                divisor--;
 163        }
 164
 165        if (factor > 0xfff0)
 166                return -EINVAL;
 167
 168        factor = 0x10000 - factor;
 169        a = (factor & 0xff00) | divisor;
 170
 171        /*
 172         * CH341A buffers data until a full endpoint-size packet (32 bytes)
 173         * has been received unless bit 7 is set.
 174         */
 175        a |= BIT(7);
 176
 177        r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a);
 178        if (r)
 179                return r;
 180
 181        r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr);
 182        if (r)
 183                return r;
 184
 185        return r;
 186}
 187
 188static int ch341_set_handshake(struct usb_device *dev, u8 control)
 189{
 190        return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
 191}
 192
 193static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 194{
 195        const unsigned int size = 2;
 196        char *buffer;
 197        int r;
 198        unsigned long flags;
 199
 200        buffer = kmalloc(size, GFP_KERNEL);
 201        if (!buffer)
 202                return -ENOMEM;
 203
 204        r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
 205        if (r < 0)
 206                goto out;
 207
 208        spin_lock_irqsave(&priv->lock, flags);
 209        priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 210        spin_unlock_irqrestore(&priv->lock, flags);
 211
 212out:    kfree(buffer);
 213        return r;
 214}
 215
 216/* -------------------------------------------------------------------------- */
 217
 218static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 219{
 220        const unsigned int size = 2;
 221        char *buffer;
 222        int r;
 223
 224        buffer = kmalloc(size, GFP_KERNEL);
 225        if (!buffer)
 226                return -ENOMEM;
 227
 228        /* expect two bytes 0x27 0x00 */
 229        r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
 230        if (r < 0)
 231                goto out;
 232        dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
 233
 234        r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
 235        if (r < 0)
 236                goto out;
 237
 238        r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);
 239        if (r < 0)
 240                goto out;
 241
 242        r = ch341_set_handshake(dev, priv->mcr);
 243
 244out:    kfree(buffer);
 245        return r;
 246}
 247
 248static int ch341_port_probe(struct usb_serial_port *port)
 249{
 250        struct ch341_private *priv;
 251        int r;
 252
 253        priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 254        if (!priv)
 255                return -ENOMEM;
 256
 257        spin_lock_init(&priv->lock);
 258        priv->baud_rate = DEFAULT_BAUD_RATE;
 259        /*
 260         * Some CH340 devices appear unable to change the initial LCR
 261         * settings, so set a sane 8N1 default.
 262         */
 263        priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
 264
 265        r = ch341_configure(port->serial->dev, priv);
 266        if (r < 0)
 267                goto error;
 268
 269        usb_set_serial_port_data(port, priv);
 270        return 0;
 271
 272error:  kfree(priv);
 273        return r;
 274}
 275
 276static int ch341_port_remove(struct usb_serial_port *port)
 277{
 278        struct ch341_private *priv;
 279
 280        priv = usb_get_serial_port_data(port);
 281        kfree(priv);
 282
 283        return 0;
 284}
 285
 286static int ch341_carrier_raised(struct usb_serial_port *port)
 287{
 288        struct ch341_private *priv = usb_get_serial_port_data(port);
 289        if (priv->msr & CH341_BIT_DCD)
 290                return 1;
 291        return 0;
 292}
 293
 294static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 295{
 296        struct ch341_private *priv = usb_get_serial_port_data(port);
 297        unsigned long flags;
 298
 299        /* drop DTR and RTS */
 300        spin_lock_irqsave(&priv->lock, flags);
 301        if (on)
 302                priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
 303        else
 304                priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 305        spin_unlock_irqrestore(&priv->lock, flags);
 306        ch341_set_handshake(port->serial->dev, priv->mcr);
 307}
 308
 309static void ch341_close(struct usb_serial_port *port)
 310{
 311        usb_serial_generic_close(port);
 312        usb_kill_urb(port->interrupt_in_urb);
 313}
 314
 315
 316/* open this device, set default parameters */
 317static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 318{
 319        struct ch341_private *priv = usb_get_serial_port_data(port);
 320        int r;
 321
 322        if (tty)
 323                ch341_set_termios(tty, port, NULL);
 324
 325        dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
 326        r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 327        if (r) {
 328                dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
 329                        __func__, r);
 330                return r;
 331        }
 332
 333        r = ch341_get_status(port->serial->dev, priv);
 334        if (r < 0) {
 335                dev_err(&port->dev, "failed to read modem status: %d\n", r);
 336                goto err_kill_interrupt_urb;
 337        }
 338
 339        r = usb_serial_generic_open(tty, port);
 340        if (r)
 341                goto err_kill_interrupt_urb;
 342
 343        return 0;
 344
 345err_kill_interrupt_urb:
 346        usb_kill_urb(port->interrupt_in_urb);
 347
 348        return r;
 349}
 350
 351/* Old_termios contains the original termios settings and
 352 * tty->termios contains the new setting to be used.
 353 */
 354static void ch341_set_termios(struct tty_struct *tty,
 355                struct usb_serial_port *port, struct ktermios *old_termios)
 356{
 357        struct ch341_private *priv = usb_get_serial_port_data(port);
 358        unsigned baud_rate;
 359        unsigned long flags;
 360        u8 lcr;
 361        int r;
 362
 363        /* redundant changes may cause the chip to lose bytes */
 364        if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 365                return;
 366
 367        baud_rate = tty_get_baud_rate(tty);
 368
 369        lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 370
 371        switch (C_CSIZE(tty)) {
 372        case CS5:
 373                lcr |= CH341_LCR_CS5;
 374                break;
 375        case CS6:
 376                lcr |= CH341_LCR_CS6;
 377                break;
 378        case CS7:
 379                lcr |= CH341_LCR_CS7;
 380                break;
 381        case CS8:
 382                lcr |= CH341_LCR_CS8;
 383                break;
 384        }
 385
 386        if (C_PARENB(tty)) {
 387                lcr |= CH341_LCR_ENABLE_PAR;
 388                if (C_PARODD(tty) == 0)
 389                        lcr |= CH341_LCR_PAR_EVEN;
 390                if (C_CMSPAR(tty))
 391                        lcr |= CH341_LCR_MARK_SPACE;
 392        }
 393
 394        if (C_CSTOPB(tty))
 395                lcr |= CH341_LCR_STOP_BITS_2;
 396
 397        if (baud_rate) {
 398                priv->baud_rate = baud_rate;
 399
 400                r = ch341_set_baudrate_lcr(port->serial->dev, priv, lcr);
 401                if (r < 0 && old_termios) {
 402                        priv->baud_rate = tty_termios_baud_rate(old_termios);
 403                        tty_termios_copy_hw(&tty->termios, old_termios);
 404                } else if (r == 0) {
 405                        priv->lcr = lcr;
 406                }
 407        }
 408
 409        spin_lock_irqsave(&priv->lock, flags);
 410        if (C_BAUD(tty) == B0)
 411                priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 412        else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
 413                priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
 414        spin_unlock_irqrestore(&priv->lock, flags);
 415
 416        ch341_set_handshake(port->serial->dev, priv->mcr);
 417}
 418
 419static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 420{
 421        const uint16_t ch341_break_reg =
 422                        ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 423        struct usb_serial_port *port = tty->driver_data;
 424        int r;
 425        uint16_t reg_contents;
 426        uint8_t *break_reg;
 427
 428        break_reg = kmalloc(2, GFP_KERNEL);
 429        if (!break_reg)
 430                return;
 431
 432        r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 433                        ch341_break_reg, 0, break_reg, 2);
 434        if (r < 0) {
 435                dev_err(&port->dev, "%s - USB control read error (%d)\n",
 436                                __func__, r);
 437                goto out;
 438        }
 439        dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 440                __func__, break_reg[0], break_reg[1]);
 441        if (break_state != 0) {
 442                dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 443                break_reg[0] &= ~CH341_NBREAK_BITS;
 444                break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 445        } else {
 446                dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 447                break_reg[0] |= CH341_NBREAK_BITS;
 448                break_reg[1] |= CH341_LCR_ENABLE_TX;
 449        }
 450        dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 451                __func__, break_reg[0], break_reg[1]);
 452        reg_contents = get_unaligned_le16(break_reg);
 453        r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 454                        ch341_break_reg, reg_contents);
 455        if (r < 0)
 456                dev_err(&port->dev, "%s - USB control write error (%d)\n",
 457                                __func__, r);
 458out:
 459        kfree(break_reg);
 460}
 461
 462static int ch341_tiocmset(struct tty_struct *tty,
 463                          unsigned int set, unsigned int clear)
 464{
 465        struct usb_serial_port *port = tty->driver_data;
 466        struct ch341_private *priv = usb_get_serial_port_data(port);
 467        unsigned long flags;
 468        u8 control;
 469
 470        spin_lock_irqsave(&priv->lock, flags);
 471        if (set & TIOCM_RTS)
 472                priv->mcr |= CH341_BIT_RTS;
 473        if (set & TIOCM_DTR)
 474                priv->mcr |= CH341_BIT_DTR;
 475        if (clear & TIOCM_RTS)
 476                priv->mcr &= ~CH341_BIT_RTS;
 477        if (clear & TIOCM_DTR)
 478                priv->mcr &= ~CH341_BIT_DTR;
 479        control = priv->mcr;
 480        spin_unlock_irqrestore(&priv->lock, flags);
 481
 482        return ch341_set_handshake(port->serial->dev, control);
 483}
 484
 485static void ch341_update_status(struct usb_serial_port *port,
 486                                        unsigned char *data, size_t len)
 487{
 488        struct ch341_private *priv = usb_get_serial_port_data(port);
 489        struct tty_struct *tty;
 490        unsigned long flags;
 491        u8 status;
 492        u8 delta;
 493        int ret;
 494
 495        if (len < 4)
 496                return;
 497
 498        status = ~data[2] & CH341_BITS_MODEM_STAT;
 499
 500        spin_lock_irqsave(&priv->lock, flags);
 501        delta = status ^ priv->msr;
 502        priv->msr = status;
 503        spin_unlock_irqrestore(&priv->lock, flags);
 504
 505        if (data[1] & CH341_MULT_STAT)
 506                dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
 507
 508        if (!delta)
 509                return;
 510
 511        if (delta & CH341_BIT_CTS)
 512                port->icount.cts++;
 513        if (delta & CH341_BIT_DSR)
 514                port->icount.dsr++;
 515        if (delta & CH341_BIT_RI)
 516                port->icount.rng++;
 517        if (delta & CH341_BIT_DCD) {
 518                port->icount.dcd++;
 519                tty = tty_port_tty_get(&port->port);
 520                if (tty) {
 521                        usb_serial_handle_dcd_change(port, tty,
 522                                                status & CH341_BIT_DCD);
 523                        tty_kref_put(tty);
 524                }
 525
 526                ret = ch341_get_status(port->serial->dev, priv);
 527                if (ret < 0) {
 528                        dev_err(&port->dev, "failed to read modem status: %d\n",
 529                                ret);
 530                }
 531        }
 532
 533        wake_up_interruptible(&port->port.delta_msr_wait);
 534}
 535
 536static void ch341_read_int_callback(struct urb *urb)
 537{
 538        struct usb_serial_port *port = urb->context;
 539        unsigned char *data = urb->transfer_buffer;
 540        unsigned int len = urb->actual_length;
 541        int status;
 542
 543        switch (urb->status) {
 544        case 0:
 545                /* success */
 546                break;
 547        case -ECONNRESET:
 548        case -ENOENT:
 549        case -ESHUTDOWN:
 550                /* this urb is terminated, clean up */
 551                dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
 552                        __func__, urb->status);
 553                return;
 554        default:
 555                dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
 556                        __func__, urb->status);
 557                goto exit;
 558        }
 559
 560        usb_serial_debug_data(&port->dev, __func__, len, data);
 561        ch341_update_status(port, data, len);
 562exit:
 563        status = usb_submit_urb(urb, GFP_ATOMIC);
 564        if (status) {
 565                dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
 566                        __func__, status);
 567        }
 568}
 569
 570static int ch341_tiocmget(struct tty_struct *tty)
 571{
 572        struct usb_serial_port *port = tty->driver_data;
 573        struct ch341_private *priv = usb_get_serial_port_data(port);
 574        unsigned long flags;
 575        u8 mcr;
 576        u8 status;
 577        unsigned int result;
 578
 579        spin_lock_irqsave(&priv->lock, flags);
 580        mcr = priv->mcr;
 581        status = priv->msr;
 582        spin_unlock_irqrestore(&priv->lock, flags);
 583
 584        result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 585                  | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 586                  | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 587                  | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 588                  | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 589                  | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 590
 591        dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 592
 593        return result;
 594}
 595
 596static int ch341_reset_resume(struct usb_serial *serial)
 597{
 598        struct ch341_private *priv;
 599
 600        priv = usb_get_serial_port_data(serial->port[0]);
 601
 602        /* reconfigure ch341 serial port after bus-reset */
 603        ch341_configure(serial->dev, priv);
 604
 605        return 0;
 606}
 607
 608static struct usb_serial_driver ch341_device = {
 609        .driver = {
 610                .owner  = THIS_MODULE,
 611                .name   = "ch341-uart",
 612        },
 613        .id_table          = id_table,
 614        .num_ports         = 1,
 615        .open              = ch341_open,
 616        .dtr_rts           = ch341_dtr_rts,
 617        .carrier_raised    = ch341_carrier_raised,
 618        .close             = ch341_close,
 619        .set_termios       = ch341_set_termios,
 620        .break_ctl         = ch341_break_ctl,
 621        .tiocmget          = ch341_tiocmget,
 622        .tiocmset          = ch341_tiocmset,
 623        .tiocmiwait        = usb_serial_generic_tiocmiwait,
 624        .read_int_callback = ch341_read_int_callback,
 625        .port_probe        = ch341_port_probe,
 626        .port_remove       = ch341_port_remove,
 627        .reset_resume      = ch341_reset_resume,
 628};
 629
 630static struct usb_serial_driver * const serial_drivers[] = {
 631        &ch341_device, NULL
 632};
 633
 634module_usb_serial_driver(serial_drivers, id_table);
 635
 636MODULE_LICENSE("GPL v2");
 637