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 mcr; 97 u8 msr; 98 u8 lcr; 99 }; 100 101 static void ch341_set_termios(struct tty_struct *tty, 102 struct usb_serial_port *port, 103 struct ktermios *old_termios); 104 105 static int ch341_control_out(struct usb_device *dev, u8 request, 106 u16 value, u16 index) 107 { 108 int r; 109 110 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__, 111 request, value, index); 112 113 r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request, 114 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT, 115 value, index, NULL, 0, DEFAULT_TIMEOUT); 116 if (r < 0) 117 dev_err(&dev->dev, "failed to send control message: %d\n", r); 118 119 return r; 120 } 121 122 static int ch341_control_in(struct usb_device *dev, 123 u8 request, u16 value, u16 index, 124 char *buf, unsigned bufsize) 125 { 126 int r; 127 128 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__, 129 request, value, index, bufsize); 130 131 r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request, 132 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN, 133 value, index, buf, bufsize, DEFAULT_TIMEOUT); 134 if (r < bufsize) { 135 if (r >= 0) { 136 dev_err(&dev->dev, 137 "short control message received (%d < %u)\n", 138 r, bufsize); 139 r = -EIO; 140 } 141 142 dev_err(&dev->dev, "failed to receive control message: %d\n", 143 r); 144 return r; 145 } 146 147 return 0; 148 } 149 150 static int ch341_set_baudrate_lcr(struct usb_device *dev, 151 struct ch341_private *priv, u8 lcr) 152 { 153 short a; 154 int r; 155 unsigned long factor; 156 short divisor; 157 158 if (!priv->baud_rate) 159 return -EINVAL; 160 factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate); 161 divisor = CH341_BAUDBASE_DIVMAX; 162 163 while ((factor > 0xfff0) && divisor) { 164 factor >>= 3; 165 divisor--; 166 } 167 168 if (factor > 0xfff0) 169 return -EINVAL; 170 171 factor = 0x10000 - factor; 172 a = (factor & 0xff00) | divisor; 173 174 /* 175 * CH341A buffers data until a full endpoint-size packet (32 bytes) 176 * has been received unless bit 7 is set. 177 */ 178 a |= BIT(7); 179 180 r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a); 181 if (r) 182 return r; 183 184 r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr); 185 if (r) 186 return r; 187 188 return r; 189 } 190 191 static int ch341_set_handshake(struct usb_device *dev, u8 control) 192 { 193 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0); 194 } 195 196 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv) 197 { 198 const unsigned int size = 2; 199 char *buffer; 200 int r; 201 unsigned long flags; 202 203 buffer = kmalloc(size, GFP_KERNEL); 204 if (!buffer) 205 return -ENOMEM; 206 207 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size); 208 if (r < 0) 209 goto out; 210 211 spin_lock_irqsave(&priv->lock, flags); 212 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT; 213 spin_unlock_irqrestore(&priv->lock, flags); 214 215 out: kfree(buffer); 216 return r; 217 } 218 219 /* -------------------------------------------------------------------------- */ 220 221 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) 222 { 223 const unsigned int size = 2; 224 char *buffer; 225 int r; 226 227 buffer = kmalloc(size, GFP_KERNEL); 228 if (!buffer) 229 return -ENOMEM; 230 231 /* expect two bytes 0x27 0x00 */ 232 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size); 233 if (r < 0) 234 goto out; 235 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]); 236 237 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0); 238 if (r < 0) 239 goto out; 240 241 r = ch341_set_baudrate_lcr(dev, priv, priv->lcr); 242 if (r < 0) 243 goto out; 244 245 r = ch341_set_handshake(dev, priv->mcr); 246 247 out: kfree(buffer); 248 return r; 249 } 250 251 static int ch341_port_probe(struct usb_serial_port *port) 252 { 253 struct ch341_private *priv; 254 int r; 255 256 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL); 257 if (!priv) 258 return -ENOMEM; 259 260 spin_lock_init(&priv->lock); 261 priv->baud_rate = DEFAULT_BAUD_RATE; 262 /* 263 * Some CH340 devices appear unable to change the initial LCR 264 * settings, so set a sane 8N1 default. 265 */ 266 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8; 267 268 r = ch341_configure(port->serial->dev, priv); 269 if (r < 0) 270 goto error; 271 272 usb_set_serial_port_data(port, priv); 273 return 0; 274 275 error: kfree(priv); 276 return r; 277 } 278 279 static int ch341_port_remove(struct usb_serial_port *port) 280 { 281 struct ch341_private *priv; 282 283 priv = usb_get_serial_port_data(port); 284 kfree(priv); 285 286 return 0; 287 } 288 289 static int ch341_carrier_raised(struct usb_serial_port *port) 290 { 291 struct ch341_private *priv = usb_get_serial_port_data(port); 292 if (priv->msr & CH341_BIT_DCD) 293 return 1; 294 return 0; 295 } 296 297 static void ch341_dtr_rts(struct usb_serial_port *port, int on) 298 { 299 struct ch341_private *priv = usb_get_serial_port_data(port); 300 unsigned long flags; 301 302 /* drop DTR and RTS */ 303 spin_lock_irqsave(&priv->lock, flags); 304 if (on) 305 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR; 306 else 307 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR); 308 spin_unlock_irqrestore(&priv->lock, flags); 309 ch341_set_handshake(port->serial->dev, priv->mcr); 310 } 311 312 static void ch341_close(struct usb_serial_port *port) 313 { 314 usb_serial_generic_close(port); 315 usb_kill_urb(port->interrupt_in_urb); 316 } 317 318 319 /* open this device, set default parameters */ 320 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) 321 { 322 struct ch341_private *priv = usb_get_serial_port_data(port); 323 int r; 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 return r; 334 } 335 336 r = ch341_get_status(port->serial->dev, priv); 337 if (r < 0) { 338 dev_err(&port->dev, "failed to read modem status: %d\n", r); 339 goto err_kill_interrupt_urb; 340 } 341 342 r = usb_serial_generic_open(tty, port); 343 if (r) 344 goto err_kill_interrupt_urb; 345 346 return 0; 347 348 err_kill_interrupt_urb: 349 usb_kill_urb(port->interrupt_in_urb); 350 351 return r; 352 } 353 354 /* Old_termios contains the original termios settings and 355 * tty->termios contains the new setting to be used. 356 */ 357 static void ch341_set_termios(struct tty_struct *tty, 358 struct usb_serial_port *port, struct ktermios *old_termios) 359 { 360 struct ch341_private *priv = usb_get_serial_port_data(port); 361 unsigned baud_rate; 362 unsigned long flags; 363 u8 lcr; 364 int r; 365 366 /* redundant changes may cause the chip to lose bytes */ 367 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios)) 368 return; 369 370 baud_rate = tty_get_baud_rate(tty); 371 372 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX; 373 374 switch (C_CSIZE(tty)) { 375 case CS5: 376 lcr |= CH341_LCR_CS5; 377 break; 378 case CS6: 379 lcr |= CH341_LCR_CS6; 380 break; 381 case CS7: 382 lcr |= CH341_LCR_CS7; 383 break; 384 case CS8: 385 lcr |= CH341_LCR_CS8; 386 break; 387 } 388 389 if (C_PARENB(tty)) { 390 lcr |= CH341_LCR_ENABLE_PAR; 391 if (C_PARODD(tty) == 0) 392 lcr |= CH341_LCR_PAR_EVEN; 393 if (C_CMSPAR(tty)) 394 lcr |= CH341_LCR_MARK_SPACE; 395 } 396 397 if (C_CSTOPB(tty)) 398 lcr |= CH341_LCR_STOP_BITS_2; 399 400 if (baud_rate) { 401 priv->baud_rate = baud_rate; 402 403 r = ch341_set_baudrate_lcr(port->serial->dev, priv, lcr); 404 if (r < 0 && old_termios) { 405 priv->baud_rate = tty_termios_baud_rate(old_termios); 406 tty_termios_copy_hw(&tty->termios, old_termios); 407 } else if (r == 0) { 408 priv->lcr = lcr; 409 } 410 } 411 412 spin_lock_irqsave(&priv->lock, flags); 413 if (C_BAUD(tty) == B0) 414 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS); 415 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0) 416 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS); 417 spin_unlock_irqrestore(&priv->lock, flags); 418 419 ch341_set_handshake(port->serial->dev, priv->mcr); 420 } 421 422 static void ch341_break_ctl(struct tty_struct *tty, int break_state) 423 { 424 const uint16_t ch341_break_reg = 425 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK; 426 struct usb_serial_port *port = tty->driver_data; 427 int r; 428 uint16_t reg_contents; 429 uint8_t *break_reg; 430 431 break_reg = kmalloc(2, GFP_KERNEL); 432 if (!break_reg) 433 return; 434 435 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG, 436 ch341_break_reg, 0, break_reg, 2); 437 if (r < 0) { 438 dev_err(&port->dev, "%s - USB control read error (%d)\n", 439 __func__, r); 440 goto out; 441 } 442 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n", 443 __func__, break_reg[0], break_reg[1]); 444 if (break_state != 0) { 445 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__); 446 break_reg[0] &= ~CH341_NBREAK_BITS; 447 break_reg[1] &= ~CH341_LCR_ENABLE_TX; 448 } else { 449 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__); 450 break_reg[0] |= CH341_NBREAK_BITS; 451 break_reg[1] |= CH341_LCR_ENABLE_TX; 452 } 453 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n", 454 __func__, break_reg[0], break_reg[1]); 455 reg_contents = get_unaligned_le16(break_reg); 456 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG, 457 ch341_break_reg, reg_contents); 458 if (r < 0) 459 dev_err(&port->dev, "%s - USB control write error (%d)\n", 460 __func__, r); 461 out: 462 kfree(break_reg); 463 } 464 465 static int ch341_tiocmset(struct tty_struct *tty, 466 unsigned int set, unsigned int clear) 467 { 468 struct usb_serial_port *port = tty->driver_data; 469 struct ch341_private *priv = usb_get_serial_port_data(port); 470 unsigned long flags; 471 u8 control; 472 473 spin_lock_irqsave(&priv->lock, flags); 474 if (set & TIOCM_RTS) 475 priv->mcr |= CH341_BIT_RTS; 476 if (set & TIOCM_DTR) 477 priv->mcr |= CH341_BIT_DTR; 478 if (clear & TIOCM_RTS) 479 priv->mcr &= ~CH341_BIT_RTS; 480 if (clear & TIOCM_DTR) 481 priv->mcr &= ~CH341_BIT_DTR; 482 control = priv->mcr; 483 spin_unlock_irqrestore(&priv->lock, flags); 484 485 return ch341_set_handshake(port->serial->dev, control); 486 } 487 488 static void ch341_update_status(struct usb_serial_port *port, 489 unsigned char *data, size_t len) 490 { 491 struct ch341_private *priv = usb_get_serial_port_data(port); 492 struct tty_struct *tty; 493 unsigned long flags; 494 u8 status; 495 u8 delta; 496 497 if (len < 4) 498 return; 499 500 status = ~data[2] & CH341_BITS_MODEM_STAT; 501 502 spin_lock_irqsave(&priv->lock, flags); 503 delta = status ^ priv->msr; 504 priv->msr = status; 505 spin_unlock_irqrestore(&priv->lock, flags); 506 507 if (data[1] & CH341_MULT_STAT) 508 dev_dbg(&port->dev, "%s - multiple status change\n", __func__); 509 510 if (!delta) 511 return; 512 513 if (delta & CH341_BIT_CTS) 514 port->icount.cts++; 515 if (delta & CH341_BIT_DSR) 516 port->icount.dsr++; 517 if (delta & CH341_BIT_RI) 518 port->icount.rng++; 519 if (delta & CH341_BIT_DCD) { 520 port->icount.dcd++; 521 tty = tty_port_tty_get(&port->port); 522 if (tty) { 523 usb_serial_handle_dcd_change(port, tty, 524 status & CH341_BIT_DCD); 525 tty_kref_put(tty); 526 } 527 } 528 529 wake_up_interruptible(&port->port.delta_msr_wait); 530 } 531 532 static void ch341_read_int_callback(struct urb *urb) 533 { 534 struct usb_serial_port *port = urb->context; 535 unsigned char *data = urb->transfer_buffer; 536 unsigned int len = urb->actual_length; 537 int status; 538 539 switch (urb->status) { 540 case 0: 541 /* success */ 542 break; 543 case -ECONNRESET: 544 case -ENOENT: 545 case -ESHUTDOWN: 546 /* this urb is terminated, clean up */ 547 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n", 548 __func__, urb->status); 549 return; 550 default: 551 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n", 552 __func__, urb->status); 553 goto exit; 554 } 555 556 usb_serial_debug_data(&port->dev, __func__, len, data); 557 ch341_update_status(port, data, len); 558 exit: 559 status = usb_submit_urb(urb, GFP_ATOMIC); 560 if (status) { 561 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n", 562 __func__, status); 563 } 564 } 565 566 static int ch341_tiocmget(struct tty_struct *tty) 567 { 568 struct usb_serial_port *port = tty->driver_data; 569 struct ch341_private *priv = usb_get_serial_port_data(port); 570 unsigned long flags; 571 u8 mcr; 572 u8 status; 573 unsigned int result; 574 575 spin_lock_irqsave(&priv->lock, flags); 576 mcr = priv->mcr; 577 status = priv->msr; 578 spin_unlock_irqrestore(&priv->lock, flags); 579 580 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0) 581 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0) 582 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0) 583 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0) 584 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0) 585 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0); 586 587 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result); 588 589 return result; 590 } 591 592 static int ch341_reset_resume(struct usb_serial *serial) 593 { 594 struct usb_serial_port *port = serial->port[0]; 595 struct ch341_private *priv = usb_get_serial_port_data(port); 596 int ret; 597 598 /* reconfigure ch341 serial port after bus-reset */ 599 ch341_configure(serial->dev, priv); 600 601 if (tty_port_initialized(&port->port)) { 602 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO); 603 if (ret) { 604 dev_err(&port->dev, "failed to submit interrupt urb: %d\n", 605 ret); 606 return ret; 607 } 608 609 ret = ch341_get_status(port->serial->dev, priv); 610 if (ret < 0) { 611 dev_err(&port->dev, "failed to read modem status: %d\n", 612 ret); 613 } 614 } 615 616 return usb_serial_generic_resume(serial); 617 } 618 619 static struct usb_serial_driver ch341_device = { 620 .driver = { 621 .owner = THIS_MODULE, 622 .name = "ch341-uart", 623 }, 624 .id_table = id_table, 625 .num_ports = 1, 626 .open = ch341_open, 627 .dtr_rts = ch341_dtr_rts, 628 .carrier_raised = ch341_carrier_raised, 629 .close = ch341_close, 630 .set_termios = ch341_set_termios, 631 .break_ctl = ch341_break_ctl, 632 .tiocmget = ch341_tiocmget, 633 .tiocmset = ch341_tiocmset, 634 .tiocmiwait = usb_serial_generic_tiocmiwait, 635 .read_int_callback = ch341_read_int_callback, 636 .port_probe = ch341_port_probe, 637 .port_remove = ch341_port_remove, 638 .reset_resume = ch341_reset_resume, 639 }; 640 641 static struct usb_serial_driver * const serial_drivers[] = { 642 &ch341_device, NULL 643 }; 644 645 module_usb_serial_driver(serial_drivers, id_table); 646 647 MODULE_LICENSE("GPL"); 648