1 // SPDX-License-Identifier: GPL-2.0
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>
7 * ch341.c implements a serial port driver for the Winchiphead CH341.
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.
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>
24 #define DEFAULT_BAUD_RATE 9600
25 #define DEFAULT_TIMEOUT 1000
27 /* flags for IO-Bits */
28 #define CH341_BIT_RTS (1 << 6)
29 #define CH341_BIT_DTR (1 << 5)
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 */
40 /* second interrupt byte */
41 #define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
43 /* status returned in third interrupt answer byte, inverted in data
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 */
51 /* Break support - the information used to implement this was gleaned from
52 * the Net/FreeBSD uchcom.c driver by Takanori Watanabe. Domo arigato.
55 #define CH341_REQ_READ_VERSION 0x5F
56 #define CH341_REQ_WRITE_REG 0x9A
57 #define CH341_REQ_READ_REG 0x95
58 #define CH341_REQ_SERIAL_INIT 0xA1
59 #define CH341_REQ_MODEM_CTRL 0xA4
61 #define CH341_REG_BREAK 0x05
62 #define CH341_REG_LCR 0x18
63 #define CH341_NBREAK_BITS 0x01
65 #define CH341_LCR_ENABLE_RX 0x80
66 #define CH341_LCR_ENABLE_TX 0x40
67 #define CH341_LCR_MARK_SPACE 0x20
68 #define CH341_LCR_PAR_EVEN 0x10
69 #define CH341_LCR_ENABLE_PAR 0x08
70 #define CH341_LCR_STOP_BITS_2 0x04
71 #define CH341_LCR_CS8 0x03
72 #define CH341_LCR_CS7 0x02
73 #define CH341_LCR_CS6 0x01
74 #define CH341_LCR_CS5 0x00
76 static const struct usb_device_id id_table[] = {
77 { USB_DEVICE(0x4348, 0x5523) },
78 { USB_DEVICE(0x1a86, 0x7523) },
79 { USB_DEVICE(0x1a86, 0x5523) },
82 MODULE_DEVICE_TABLE(usb, id_table);
84 struct ch341_private {
85 spinlock_t lock; /* access lock */
86 unsigned baud_rate; /* set baud rate */
92 static void ch341_set_termios(struct tty_struct *tty,
93 struct usb_serial_port *port,
94 struct ktermios *old_termios);
96 static int ch341_control_out(struct usb_device *dev, u8 request,
101 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
102 request, value, index);
104 r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
105 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
106 value, index, NULL, 0, DEFAULT_TIMEOUT);
108 dev_err(&dev->dev, "failed to send control message: %d\n", r);
113 static int ch341_control_in(struct usb_device *dev,
114 u8 request, u16 value, u16 index,
115 char *buf, unsigned bufsize)
119 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
120 request, value, index, bufsize);
122 r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
123 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
124 value, index, buf, bufsize, DEFAULT_TIMEOUT);
125 if (r < (int)bufsize) {
128 "short control message received (%d < %u)\n",
133 dev_err(&dev->dev, "failed to receive control message: %d\n",
141 #define CH341_CLKRATE 48000000
142 #define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
143 #define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
145 static const speed_t ch341_min_rates[] = {
153 * The device line speed is given by the following equation:
155 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
159 * 2 <= div <= 256 if fact = 0, or
160 * 9 <= div <= 256 if fact = 1
162 static int ch341_get_divisor(speed_t speed)
164 unsigned int fact, div, clk_div;
168 * Clamp to supported range, this makes the (ps < 0) and (div < 2)
169 * sanity checks below redundant.
171 speed = clamp(speed, 46U, 3000000U);
174 * Start with highest possible base clock (fact = 1) that will give a
175 * divisor strictly less than 512.
178 for (ps = 3; ps >= 0; ps--) {
179 if (speed > ch341_min_rates[ps])
186 /* Determine corresponding divisor, rounding down. */
187 clk_div = CH341_CLK_DIV(ps, fact);
188 div = CH341_CLKRATE / (clk_div * speed);
190 /* Halve base clock (fact = 0) if required. */
191 if (div < 9 || div > 255) {
201 * Pick next divisor if resulting rate is closer to the requested one,
202 * scale up to avoid rounding errors on low rates.
204 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
205 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
209 * Prefer lower base clock (fact = 0) if even divisor.
211 * Note that this makes the receiver more tolerant to errors.
213 if (fact == 1 && div % 2 == 0) {
218 return (0x100 - div) << 8 | fact << 2 | ps;
221 static int ch341_set_baudrate_lcr(struct usb_device *dev,
222 struct ch341_private *priv, u8 lcr)
227 if (!priv->baud_rate)
230 val = ch341_get_divisor(priv->baud_rate);
235 * CH341A buffers data until a full endpoint-size packet (32 bytes)
236 * has been received unless bit 7 is set.
240 r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, val);
244 r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr);
251 static int ch341_set_handshake(struct usb_device *dev, u8 control)
253 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
256 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
258 const unsigned int size = 2;
263 buffer = kmalloc(size, GFP_KERNEL);
267 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
271 spin_lock_irqsave(&priv->lock, flags);
272 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
273 spin_unlock_irqrestore(&priv->lock, flags);
279 /* -------------------------------------------------------------------------- */
281 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
283 const unsigned int size = 2;
287 buffer = kmalloc(size, GFP_KERNEL);
291 /* expect two bytes 0x27 0x00 */
292 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
295 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
297 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
301 r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);
305 r = ch341_set_handshake(dev, priv->mcr);
311 static int ch341_port_probe(struct usb_serial_port *port)
313 struct ch341_private *priv;
316 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
320 spin_lock_init(&priv->lock);
321 priv->baud_rate = DEFAULT_BAUD_RATE;
323 * Some CH340 devices appear unable to change the initial LCR
324 * settings, so set a sane 8N1 default.
326 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
328 r = ch341_configure(port->serial->dev, priv);
332 usb_set_serial_port_data(port, priv);
339 static int ch341_port_remove(struct usb_serial_port *port)
341 struct ch341_private *priv;
343 priv = usb_get_serial_port_data(port);
349 static int ch341_carrier_raised(struct usb_serial_port *port)
351 struct ch341_private *priv = usb_get_serial_port_data(port);
352 if (priv->msr & CH341_BIT_DCD)
357 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
359 struct ch341_private *priv = usb_get_serial_port_data(port);
362 /* drop DTR and RTS */
363 spin_lock_irqsave(&priv->lock, flags);
365 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
367 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
368 spin_unlock_irqrestore(&priv->lock, flags);
369 ch341_set_handshake(port->serial->dev, priv->mcr);
372 static void ch341_close(struct usb_serial_port *port)
374 usb_serial_generic_close(port);
375 usb_kill_urb(port->interrupt_in_urb);
379 /* open this device, set default parameters */
380 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
382 struct ch341_private *priv = usb_get_serial_port_data(port);
386 ch341_set_termios(tty, port, NULL);
388 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
389 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
391 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
396 r = ch341_get_status(port->serial->dev, priv);
398 dev_err(&port->dev, "failed to read modem status: %d\n", r);
399 goto err_kill_interrupt_urb;
402 r = usb_serial_generic_open(tty, port);
404 goto err_kill_interrupt_urb;
408 err_kill_interrupt_urb:
409 usb_kill_urb(port->interrupt_in_urb);
414 /* Old_termios contains the original termios settings and
415 * tty->termios contains the new setting to be used.
417 static void ch341_set_termios(struct tty_struct *tty,
418 struct usb_serial_port *port, struct ktermios *old_termios)
420 struct ch341_private *priv = usb_get_serial_port_data(port);
426 /* redundant changes may cause the chip to lose bytes */
427 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
430 baud_rate = tty_get_baud_rate(tty);
432 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
434 switch (C_CSIZE(tty)) {
436 lcr |= CH341_LCR_CS5;
439 lcr |= CH341_LCR_CS6;
442 lcr |= CH341_LCR_CS7;
445 lcr |= CH341_LCR_CS8;
450 lcr |= CH341_LCR_ENABLE_PAR;
451 if (C_PARODD(tty) == 0)
452 lcr |= CH341_LCR_PAR_EVEN;
454 lcr |= CH341_LCR_MARK_SPACE;
458 lcr |= CH341_LCR_STOP_BITS_2;
461 priv->baud_rate = baud_rate;
463 r = ch341_set_baudrate_lcr(port->serial->dev, priv, lcr);
464 if (r < 0 && old_termios) {
465 priv->baud_rate = tty_termios_baud_rate(old_termios);
466 tty_termios_copy_hw(&tty->termios, old_termios);
472 spin_lock_irqsave(&priv->lock, flags);
473 if (C_BAUD(tty) == B0)
474 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
475 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
476 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
477 spin_unlock_irqrestore(&priv->lock, flags);
479 ch341_set_handshake(port->serial->dev, priv->mcr);
482 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
484 const uint16_t ch341_break_reg =
485 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
486 struct usb_serial_port *port = tty->driver_data;
488 uint16_t reg_contents;
491 break_reg = kmalloc(2, GFP_KERNEL);
495 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
496 ch341_break_reg, 0, break_reg, 2);
498 dev_err(&port->dev, "%s - USB control read error (%d)\n",
502 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
503 __func__, break_reg[0], break_reg[1]);
504 if (break_state != 0) {
505 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
506 break_reg[0] &= ~CH341_NBREAK_BITS;
507 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
509 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
510 break_reg[0] |= CH341_NBREAK_BITS;
511 break_reg[1] |= CH341_LCR_ENABLE_TX;
513 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
514 __func__, break_reg[0], break_reg[1]);
515 reg_contents = get_unaligned_le16(break_reg);
516 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
517 ch341_break_reg, reg_contents);
519 dev_err(&port->dev, "%s - USB control write error (%d)\n",
525 static int ch341_tiocmset(struct tty_struct *tty,
526 unsigned int set, unsigned int clear)
528 struct usb_serial_port *port = tty->driver_data;
529 struct ch341_private *priv = usb_get_serial_port_data(port);
533 spin_lock_irqsave(&priv->lock, flags);
535 priv->mcr |= CH341_BIT_RTS;
537 priv->mcr |= CH341_BIT_DTR;
538 if (clear & TIOCM_RTS)
539 priv->mcr &= ~CH341_BIT_RTS;
540 if (clear & TIOCM_DTR)
541 priv->mcr &= ~CH341_BIT_DTR;
543 spin_unlock_irqrestore(&priv->lock, flags);
545 return ch341_set_handshake(port->serial->dev, control);
548 static void ch341_update_status(struct usb_serial_port *port,
549 unsigned char *data, size_t len)
551 struct ch341_private *priv = usb_get_serial_port_data(port);
552 struct tty_struct *tty;
560 status = ~data[2] & CH341_BITS_MODEM_STAT;
562 spin_lock_irqsave(&priv->lock, flags);
563 delta = status ^ priv->msr;
565 spin_unlock_irqrestore(&priv->lock, flags);
567 if (data[1] & CH341_MULT_STAT)
568 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
573 if (delta & CH341_BIT_CTS)
575 if (delta & CH341_BIT_DSR)
577 if (delta & CH341_BIT_RI)
579 if (delta & CH341_BIT_DCD) {
581 tty = tty_port_tty_get(&port->port);
583 usb_serial_handle_dcd_change(port, tty,
584 status & CH341_BIT_DCD);
589 wake_up_interruptible(&port->port.delta_msr_wait);
592 static void ch341_read_int_callback(struct urb *urb)
594 struct usb_serial_port *port = urb->context;
595 unsigned char *data = urb->transfer_buffer;
596 unsigned int len = urb->actual_length;
599 switch (urb->status) {
606 /* this urb is terminated, clean up */
607 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
608 __func__, urb->status);
611 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
612 __func__, urb->status);
616 usb_serial_debug_data(&port->dev, __func__, len, data);
617 ch341_update_status(port, data, len);
619 status = usb_submit_urb(urb, GFP_ATOMIC);
621 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
626 static int ch341_tiocmget(struct tty_struct *tty)
628 struct usb_serial_port *port = tty->driver_data;
629 struct ch341_private *priv = usb_get_serial_port_data(port);
635 spin_lock_irqsave(&priv->lock, flags);
638 spin_unlock_irqrestore(&priv->lock, flags);
640 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
641 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
642 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
643 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
644 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
645 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
647 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
652 static int ch341_reset_resume(struct usb_serial *serial)
654 struct usb_serial_port *port = serial->port[0];
655 struct ch341_private *priv;
658 priv = usb_get_serial_port_data(port);
662 /* reconfigure ch341 serial port after bus-reset */
663 ch341_configure(serial->dev, priv);
665 if (tty_port_initialized(&port->port)) {
666 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
668 dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
673 ret = ch341_get_status(port->serial->dev, priv);
675 dev_err(&port->dev, "failed to read modem status: %d\n",
680 return usb_serial_generic_resume(serial);
683 static struct usb_serial_driver ch341_device = {
685 .owner = THIS_MODULE,
686 .name = "ch341-uart",
688 .id_table = id_table,
691 .dtr_rts = ch341_dtr_rts,
692 .carrier_raised = ch341_carrier_raised,
693 .close = ch341_close,
694 .set_termios = ch341_set_termios,
695 .break_ctl = ch341_break_ctl,
696 .tiocmget = ch341_tiocmget,
697 .tiocmset = ch341_tiocmset,
698 .tiocmiwait = usb_serial_generic_tiocmiwait,
699 .read_int_callback = ch341_read_int_callback,
700 .port_probe = ch341_port_probe,
701 .port_remove = ch341_port_remove,
702 .reset_resume = ch341_reset_resume,
705 static struct usb_serial_driver * const serial_drivers[] = {
709 module_usb_serial_driver(serial_drivers, id_table);
711 MODULE_LICENSE("GPL v2");