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 82 static const struct usb_device_id id_table[] = { 83 { USB_DEVICE(0x4348, 0x5523) }, 84 { USB_DEVICE(0x1a86, 0x7523) }, 85 { USB_DEVICE(0x1a86, 0x5523) }, 86 { }, 87 }; 88 MODULE_DEVICE_TABLE(usb, id_table); 89 90 struct 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 98 static void ch341_set_termios(struct tty_struct *tty, 99 struct usb_serial_port *port, 100 struct ktermios *old_termios); 101 102 static 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 } 118 119 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, "%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 } 146 147 static 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 } 187 188 static int ch341_set_handshake(struct usb_device *dev, u8 control) 189 { 190 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0); 191 } 192 193 static 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); 211 212 out: kfree(buffer); 213 return r; 214 } 215 216 /* -------------------------------------------------------------------------- */ 217 218 static 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); 243 244 out: kfree(buffer); 245 return r; 246 } 247 248 static 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; 271 272 error: kfree(priv); 273 return r; 274 } 275 276 static 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 } 285 286 static 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 } 293 294 static 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 } 308 309 static 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 */ 317 static 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; 344 345 err_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 */ 354 static 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 } 418 419 static 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); 458 out: 459 kfree(break_reg); 460 } 461 462 static 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 } 484 485 static 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; 493 494 if (len < 4) 495 return; 496 497 status = ~data[2] & CH341_BITS_MODEM_STAT; 498 499 spin_lock_irqsave(&priv->lock, flags); 500 delta = status ^ priv->msr; 501 priv->msr = status; 502 spin_unlock_irqrestore(&priv->lock, flags); 503 504 if (data[1] & CH341_MULT_STAT) 505 dev_dbg(&port->dev, "%s - multiple status change\n", __func__); 506 507 if (!delta) 508 return; 509 510 if (delta & CH341_BIT_CTS) 511 port->icount.cts++; 512 if (delta & CH341_BIT_DSR) 513 port->icount.dsr++; 514 if (delta & CH341_BIT_RI) 515 port->icount.rng++; 516 if (delta & CH341_BIT_DCD) { 517 port->icount.dcd++; 518 tty = tty_port_tty_get(&port->port); 519 if (tty) { 520 usb_serial_handle_dcd_change(port, tty, 521 status & CH341_BIT_DCD); 522 tty_kref_put(tty); 523 } 524 } 525 526 wake_up_interruptible(&port->port.delta_msr_wait); 527 } 528 529 static void ch341_read_int_callback(struct urb *urb) 530 { 531 struct usb_serial_port *port = urb->context; 532 unsigned char *data = urb->transfer_buffer; 533 unsigned int len = urb->actual_length; 534 int status; 535 536 switch (urb->status) { 537 case 0: 538 /* success */ 539 break; 540 case -ECONNRESET: 541 case -ENOENT: 542 case -ESHUTDOWN: 543 /* this urb is terminated, clean up */ 544 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n", 545 __func__, urb->status); 546 return; 547 default: 548 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n", 549 __func__, urb->status); 550 goto exit; 551 } 552 553 usb_serial_debug_data(&port->dev, __func__, len, data); 554 ch341_update_status(port, data, len); 555 exit: 556 status = usb_submit_urb(urb, GFP_ATOMIC); 557 if (status) { 558 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n", 559 __func__, status); 560 } 561 } 562 563 static int ch341_tiocmget(struct tty_struct *tty) 564 { 565 struct usb_serial_port *port = tty->driver_data; 566 struct ch341_private *priv = usb_get_serial_port_data(port); 567 unsigned long flags; 568 u8 mcr; 569 u8 status; 570 unsigned int result; 571 572 spin_lock_irqsave(&priv->lock, flags); 573 mcr = priv->mcr; 574 status = priv->msr; 575 spin_unlock_irqrestore(&priv->lock, flags); 576 577 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0) 578 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0) 579 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0) 580 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0) 581 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0) 582 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0); 583 584 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result); 585 586 return result; 587 } 588 589 static int ch341_reset_resume(struct usb_serial *serial) 590 { 591 struct usb_serial_port *port = serial->port[0]; 592 struct ch341_private *priv = usb_get_serial_port_data(port); 593 int ret; 594 595 /* reconfigure ch341 serial port after bus-reset */ 596 ch341_configure(serial->dev, priv); 597 598 if (tty_port_initialized(&port->port)) { 599 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO); 600 if (ret) { 601 dev_err(&port->dev, "failed to submit interrupt urb: %d\n", 602 ret); 603 return ret; 604 } 605 606 ret = ch341_get_status(port->serial->dev, priv); 607 if (ret < 0) { 608 dev_err(&port->dev, "failed to read modem status: %d\n", 609 ret); 610 } 611 } 612 613 return usb_serial_generic_resume(serial); 614 } 615 616 static struct usb_serial_driver ch341_device = { 617 .driver = { 618 .owner = THIS_MODULE, 619 .name = "ch341-uart", 620 }, 621 .id_table = id_table, 622 .num_ports = 1, 623 .open = ch341_open, 624 .dtr_rts = ch341_dtr_rts, 625 .carrier_raised = ch341_carrier_raised, 626 .close = ch341_close, 627 .set_termios = ch341_set_termios, 628 .break_ctl = ch341_break_ctl, 629 .tiocmget = ch341_tiocmget, 630 .tiocmset = ch341_tiocmset, 631 .tiocmiwait = usb_serial_generic_tiocmiwait, 632 .read_int_callback = ch341_read_int_callback, 633 .port_probe = ch341_port_probe, 634 .port_remove = ch341_port_remove, 635 .reset_resume = ch341_reset_resume, 636 }; 637 638 static struct usb_serial_driver * const serial_drivers[] = { 639 &ch341_device, NULL 640 }; 641 642 module_usb_serial_driver(serial_drivers, id_table); 643 644 MODULE_LICENSE("GPL v2"); 645