Serial USB-driver for Winchiphead CH340/41 chip

From: Werner Cornelius
Date: Fri Sep 14 2007 - 08:54:27 EST

Hello,

I know that there has been a patch for the Winchiphead CH340/41 USB to serial
converter chips on the net, but they have been implemented with only a basic
feature and limited baudrates due to the lack of any datasheets.

I picked these patches up and added all common baudrates as well as the
complete modem control and status handling to be able of using this adapter
in nearly all applications.

Features still missing:

- character length other than 8 bits
- parity settings
- break control

I don't have an USB sniffer, if someone may send me sniffer logs for various
settings these features may be added to the driver of course.

I am not listening on this mailing list, so please address me directly if
there are any questions or comments.

The patch is against the 2.6.22.5 kernel, but should work for newer kernels,
too.

Werner

--- linux-2.6.22.5/Documentation/usb/usb-serial.txt 2007-08-23
01:23:54.000000000 +0200
+++ linux-2.6.22.5-cc/Documentation/usb/usb-serial.txt 2007-09-14
14:13:28.000000000 +0200
@@ -428,6 +428,19 @@
See http://www.uuhaus.de/linux/palmconnect.html for up-to-date
information on this driver.

+Winchiphead CH341 Driver
+
+ This driver is for the Winchiphead CH341 USB-RS232 Converter. This chip
+ also implements an IEEE 1284 parallel port, I2C and SPI, but that is not
+ supported by the driver. The protocol was analyzed from the behaviour
+ of the Windows driver, no datasheet is available at present.
+ The manufacturer's website: http://www.winchiphead.com/.
+ For any questions or problems with this driver, please contact
+ frank <at> kingswood-consulting.co.uk.
+ Extensions for universal baudrate settings and modem status/control has
+ been added by werner <at> cornelius-consult.de.
+
+
Generic Serial driver

If your device is not one of the above listed devices, compatible with
--- linux-2.6.22.5/drivers/usb/serial/Kconfig 2007-08-23 01:23:54.000000000
+0200
+++ linux-2.6.22.5-cc/drivers/usb/serial/Kconfig 2007-09-11 11:53:58.000000000
+0200
@@ -92,6 +92,17 @@
To compile this driver as a module, choose M here: the
module will be called belkin_sa.

+config USB_SERIAL_CH341
+ tristate "USB Winchiphead CH341 Single Port Serial Driver"
+ depends on USB_SERIAL
+ help
+ Say Y here if you want to use a Winchiphead CH341 single port
+ USB to serial adapter.
+
+ To compile this driver as a module, choose M here: the
+ module will be called ch341.
+
+
config USB_SERIAL_WHITEHEAT
tristate "USB ConnectTech WhiteHEAT Serial Driver"
depends on USB_SERIAL
--- linux-2.6.22.5/drivers/usb/serial/Makefile 2007-08-23 01:23:54.000000000
+0200
+++ linux-2.6.22.5-cc/drivers/usb/serial/Makefile 2007-09-11
11:54:39.000000000 +0200
@@ -15,6 +15,7 @@
obj-$(CONFIG_USB_SERIAL_AIRPRIME) += airprime.o
obj-$(CONFIG_USB_SERIAL_ARK3116) += ark3116.o
obj-$(CONFIG_USB_SERIAL_BELKIN) += belkin_sa.o
+obj-$(CONFIG_USB_SERIAL_CH341) += ch341.o
obj-$(CONFIG_USB_SERIAL_CP2101) += cp2101.o
obj-$(CONFIG_USB_SERIAL_CYBERJACK) += cyberjack.o
obj-$(CONFIG_USB_SERIAL_CYPRESS_M8) += cypress_m8.o
--- linux-2.6.22.5/drivers/usb/serial/ch341.c 1970-01-01 01:00:00.000000000
+0100
+++ linux-2.6.22.5-cc/drivers/usb/serial/ch341.c 2007-09-14 13:43:28.000000000
+0200
@@ -0,0 +1,579 @@
+/*
+ * Copyright 2007, Frank A Kingswood <frank <at> kingswood-consulting.co.uk>
+ *
+ * Copyright 2007, Werner Cornelius <werner <at> cornelius-consult.de>
+ * for changes/extenions regarding universal baud rate capability and modem
+ * line control/status routines.
+ *
+ * ch341.c implements a serial port driver for the Winchiphead CH341.
+ *
+ * The CH341 device can be used to implement an RS232 asynchronous
+ * serial port, an IEEE-1284 parallel printer port or a memory-like
+ * interface. In all cases the CH341 supports an I2C interface as well.
+ * This driver only supports the asynchronous serial interface.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+#include <linux/serial.h>
+
+#define DEFAULT_BAUD_RATE 9600
+#define DEFAULT_TIMEOUT 1000
+
+/* flags for IO-Bits */
+#define CH341_BIT_RTS (1 << 6)
+#define CH341_BIT_DTR (1 << 5)
+
+/******************************/
+/* interrupt pipe definitions */
+/******************************/
+/* always 4 interrupt bytes */
+/* first irq byte normally 0x08 */
+/* second irq byte base 0x7d + below */
+/* third irq byte base 0x94 + below */
+/* fourth irq byte normally 0xee */
+
+/* second interrupt byte */
+#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
+
+/* status returned in third interrupt answer byte, inverted in data from irq
*/
+#define CH341_BIT_CTS 0x01
+#define CH341_BIT_DSR 0x02
+#define CH341_BIT_RI 0x04
+#define CH341_BIT_DCD 0x08
+#define CH341_BITS_MODEM_STAT 0x0f /* all bits */
+
+/*******************************/
+/* baudrate calculation factor */
+/*******************************/
+#define CH341_BAUDBASE_FACTOR 1532620800
+#define CH341_BAUDBASE_DIVMAX 3
+
+static int debug;
+
+static struct usb_device_id id_table [] = {
+ { USB_DEVICE(0x4348, 0x5523) },
+ { },
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+struct ch341_private {
+ spinlock_t lock; /* access lock */
+ wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
+ unsigned baud_rate; /* set baud rate */
+ u8 line_control; /* set line control value RTS/DTR */
+ u8 line_status; /* active status of modem control inputs */
+ u8 multi_status_change; /* status changed multiple since last call */
+};
+
+static int ch341_control_out(struct usb_device *dev, u8 request,
+ u16 value, u16 index)
+{
+ int r;
+ dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
+ (int)request, (int)value, (int)index);
+
+ r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
+ USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
+ value, index, NULL, 0, DEFAULT_TIMEOUT);
+
+ return r;
+}
+
+static int ch341_control_in(struct usb_device *dev,
+ u8 request, u16 value, u16 index,
+ char *buf, unsigned bufsize)
+{
+ int r;
+ dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
+ (int)request, (int)value, (int)index, buf, (int)bufsize);
+
+ r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
+ USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
+ value, index, buf, bufsize, DEFAULT_TIMEOUT);
+ return r;
+}
+
+int ch341_set_baudrate(struct usb_device *dev, struct ch341_private *priv)
+{
+ short a, b;
+ int r;
+ unsigned long factor;
+ short divisor;
+
+ dbg("ch341_set_baudrate(%d)", priv->baud_rate);
+
+ if (!priv->baud_rate)
+ return -EINVAL;
+
+ factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
+ divisor = CH341_BAUDBASE_DIVMAX;
+
+ while ((factor > 0xfff0) && divisor) {
+ factor >>= 3;
+ divisor--;
+ }
+
+ if (factor > 0xfff0)
+ return -EINVAL;
+
+ factor = 0x10000 - factor;
+ a = (factor & 0xff00) | divisor;
+ b = factor & 0xff;
+
+ r = ch341_control_out(dev, 0x9a, 0x1312, a);
+ if (!r)
+ r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
+
+ return r;
+}
+
+int ch341_set_handshake(struct usb_device *dev, u8 control)
+{
+ dbg("ch341_set_handshake(0x%02x)", control);
+ return ch341_control_out(dev, 0xa4, ~control, 0);
+}
+
+int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
+{
+ char *buffer;
+ int r;
+ const unsigned size = 8;
+ unsigned long flags;
+
+ dbg("ch341_get_status()");
+
+ buffer = kmalloc(size, GFP_KERNEL);
+ if (!buffer)
+ return -ENOMEM;
+
+ r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
+ if ( r < 0)
+ goto out;
+
+ /* setup the private status if available */
+ if (r == 2) {
+ r = 0;
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
+ priv->multi_status_change = 0;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ } else
+ r = -EPROTO;
+
+out: kfree(buffer);
+ return r;
+}
+
+/* --------------------------------------------------------------------------
*/
+
+int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
+{
+ char *buffer;
+ int r;
+ const unsigned size = 8;
+
+ dbg("ch341_configure()");
+
+ buffer = kmalloc(size, GFP_KERNEL);
+ if (!buffer)
+ return -ENOMEM;
+
+ /* expect two bytes 0x27 0x00 */
+ r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
+ if (r < 0)
+ goto out;
+
+ r = ch341_control_out(dev, 0xa1, 0, 0);
+ if (r < 0)
+ goto out;
+
+ r = ch341_set_baudrate(dev, priv);
+ if (r < 0)
+ goto out;
+
+ /* expect two bytes 0x56 0x00 */
+ r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
+ if (r < 0)
+ goto out;
+
+ r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
+ if (r < 0)
+ goto out;
+
+ /* expect 0xff 0xee */
+ r = ch341_get_status(dev, priv);
+ if (r < 0)
+ goto out;
+
+ r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
+ if (r < 0)
+ goto out;
+
+ r = ch341_set_baudrate(dev, priv);
+ if (r < 0)
+ goto out;
+
+ r = ch341_set_handshake(dev, priv->line_control);
+ if (r < 0)
+ goto out;
+
+ /* expect 0x9f 0xee */
+ r = ch341_get_status(dev, priv);
+
+out: kfree(buffer);
+ return r;
+}
+
+/* allocate private data */
+static int ch341_attach(struct usb_serial *serial)
+{
+ struct ch341_private *priv;
+ int r;
+
+ dbg("ch341_attach()");
+
+ /* private data */
+ priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ spin_lock_init(&priv->lock);
+ init_waitqueue_head(&priv->delta_msr_wait);
+ priv->baud_rate = DEFAULT_BAUD_RATE;
+ priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
+
+ r = ch341_configure(serial->dev, priv);
+ if (r < 0)
+ goto error;
+
+ usb_set_serial_port_data(serial->port[0], priv);
+ return 0;
+
+error: kfree(priv);
+ return r;
+}
+
+static void ch341_close(struct usb_serial_port *port, struct file *filp)
+{
+ struct ch341_private *priv = usb_get_serial_port_data(port);
+ unsigned long flags;
+ unsigned int c_cflag;
+
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ /* shutdown our urbs */
+ dbg("%s - shutting down urbs", __FUNCTION__);
+ usb_kill_urb(port->write_urb);
+ usb_kill_urb(port->read_urb);
+ usb_kill_urb(port->interrupt_in_urb);
+
+ if (port->tty) {
+ c_cflag = port->tty->termios->c_cflag;
+ if (c_cflag & HUPCL) {
+ /* drop DTR and RTS */
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->line_control = 0;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ ch341_set_handshake(port->serial->dev, 0);
+ }
+ }
+ wake_up_interruptible(&priv->delta_msr_wait);
+}
+
+/* open this device, set default parameters */
+static int ch341_open(struct usb_serial_port *port, struct file *filp)
+{
+ struct usb_serial *serial = port->serial;
+ struct ch341_private *priv =
usb_get_serial_port_data(serial->port[0]);
+ int r;
+
+ dbg("ch341_open()");
+
+ priv->baud_rate = DEFAULT_BAUD_RATE;
+ priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
+
+ r = ch341_configure(serial->dev, priv);
+ if (r)
+ goto out;
+
+ r = ch341_set_handshake(serial->dev, priv->line_control);
+ if (r)
+ goto out;
+
+ r = ch341_set_baudrate(serial->dev, priv);
+ if (r)
+ goto out;
+
+ dbg("%s - submitting interrupt urb", __FUNCTION__);
+ port->interrupt_in_urb->dev = serial->dev;
+ r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
+ if (r) {
+ dev_err(&port->dev, "%s - failed submitting interrupt urb,"
+ " error %d\n", __FUNCTION__, r);
+ ch341_close(port, NULL);
+ return -EPROTO;
+ }
+
+ r = usb_serial_generic_open(port, filp);
+
+out: return r;
+}
+
+/* Old_termios contains the original termios settings and
+ * tty->termios contains the new setting to be used.
+ */
+static void ch341_set_termios(struct usb_serial_port *port,
+ struct ktermios *old_termios)
+{
+ struct ch341_private *priv = usb_get_serial_port_data(port);
+ struct tty_struct *tty = port->tty;
+ unsigned baud_rate;
+ unsigned long flags;
+
+ dbg("ch341_set_termios()");
+
+ if (!tty || !tty->termios)
+ return;
+
+ baud_rate = tty_get_baud_rate(tty);
+ priv->baud_rate = baud_rate;
+
+ if (baud_rate) {
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
+ spin_unlock_irqrestore(&priv->lock, flags);
+ ch341_set_baudrate(port->serial->dev, priv);
+ } else {
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
+ spin_unlock_irqrestore(&priv->lock, flags);
+ }
+ ch341_set_handshake(port->serial->dev, priv->line_control);
+
+ /* Unimplemented:
+ * (cflag & CSIZE) : data bits [5, 8]
+ * (cflag & PARENB) : parity {NONE, EVEN, ODD}
+ * (cflag & CSTOPB) : stop bits [1, 2]
+ */
+}
+
+static int ch341_tiocmset(struct usb_serial_port *port, struct file *file,
+ unsigned int set, unsigned int clear)
+{
+ struct ch341_private *priv = usb_get_serial_port_data(port);
+ unsigned long flags;
+ u8 control;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ if (set & TIOCM_RTS)
+ priv->line_control |= CH341_BIT_RTS;
+ if (set & TIOCM_DTR)
+ priv->line_control |= CH341_BIT_DTR;
+ if (clear & TIOCM_RTS)
+ priv->line_control &= ~CH341_BIT_RTS;
+ if (clear & TIOCM_DTR)
+ priv->line_control &= ~CH341_BIT_DTR;
+ control = priv->line_control;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return(ch341_set_handshake(port->serial->dev, control));
+}
+
+static void ch341_read_int_callback(struct urb *urb)
+{
+ struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
+ unsigned char *data = urb->transfer_buffer;
+ unsigned int actual_length = urb->actual_length;
+ int status;
+
+ dbg("%s (%d)", __FUNCTION__, port->number);
+
+ switch (urb->status) {
+ case 0:
+ /* success */
+ break;
+ case -ECONNRESET:
+ case -ENOENT:
+ case -ESHUTDOWN:
+ /* this urb is terminated, clean up */
+ dbg("%s - urb shutting down with status: %d", __FUNCTION__,
+ urb->status);
+ return;
+ default:
+ dbg("%s - nonzero urb status received: %d", __FUNCTION__,
+ urb->status);
+ goto exit;
+ }
+
+ usb_serial_debug_data(debug, &port->dev, __FUNCTION__,
+ urb->actual_length, urb->transfer_buffer);
+
+ if (actual_length >= 4) {
+ struct ch341_private *priv = usb_get_serial_port_data(port);
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
+ if ((data[1] & CH341_MULT_STAT))
+ priv->multi_status_change = 1;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ wake_up_interruptible(&priv->delta_msr_wait);
+ }
+
+exit:
+ status = usb_submit_urb(urb, GFP_ATOMIC);
+ if (status)
+ dev_err(&urb->dev->dev,
+ "%s - usb_submit_urb failed with result %d\n",
+ __FUNCTION__, status);
+}
+
+static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
+{
+ struct ch341_private *priv = usb_get_serial_port_data(port);
+ unsigned long flags;
+ u8 prevstatus;
+ u8 status;
+ u8 changed;
+ u8 multi_change = 0;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ prevstatus = priv->line_status;
+ priv->multi_status_change = 0;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ while (!multi_change) {
+ interruptible_sleep_on(&priv->delta_msr_wait);
+ /* see if a signal did it */
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+
+ spin_lock_irqsave(&priv->lock, flags);
+ status = priv->line_status;
+ multi_change = priv->multi_status_change;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ changed=prevstatus^status;
+
+ if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
+ ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
+ ((arg & TIOCM_CD) && (changed & CH341_BIT_DCD)) ||
+ ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS)) ) {
+ return 0;
+ }
+ prevstatus = status;
+ }
+
+ return 0;
+}
+
+static int ch341_ioctl(struct usb_serial_port *port, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ dbg("%s (%d) cmd = 0x%04x", __FUNCTION__, port->number, cmd);
+
+ switch (cmd) {
+ case TIOCMIWAIT:
+ dbg("%s (%d) TIOCMIWAIT", __FUNCTION__, port->number);
+ return wait_modem_info(port, arg);
+
+ default:
+ dbg("%s not supported = 0x%04x", __FUNCTION__, cmd);
+ break;
+ }
+
+ return -ENOIOCTLCMD;
+}
+
+static int ch341_tiocmget(struct usb_serial_port *port, struct file *file)
+{
+ struct ch341_private *priv = usb_get_serial_port_data(port);
+ unsigned long flags;
+ u8 mcr;
+ u8 status;
+ unsigned int result;
+
+ dbg("%s (%d)", __FUNCTION__, port->number);
+
+ spin_lock_irqsave(&priv->lock, flags);
+ mcr = priv->line_control;
+ status = priv->line_status;
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0)
+ | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0)
+ | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0)
+ | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0)
+ | ((status & CH341_BIT_RI) ? TIOCM_RI : 0)
+ | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0);
+
+ dbg("%s - result = %x", __FUNCTION__, result);
+
+ return result;
+}
+
+static struct usb_driver ch341_driver = {
+ .name = "ch341",
+ .probe = usb_serial_probe,
+ .disconnect = usb_serial_disconnect,
+ .id_table = id_table,
+ .no_dynamic_id = 1,
+};
+
+static struct usb_serial_driver ch341_device = {
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "ch341-uart",
+ },
+ .id_table = id_table,
+ .usb_driver = &ch341_driver,
+ .num_interrupt_in = 1, //NUM_DONT_CARE,
+ .num_bulk_in = 1,
+ .num_bulk_out = 1,
+ .num_ports = 1,
+ .open = ch341_open,
+ .close = ch341_close,
+ .ioctl = ch341_ioctl,
+ .set_termios = ch341_set_termios,
+ .tiocmget = ch341_tiocmget,
+ .tiocmset = ch341_tiocmset,
+ .read_int_callback= ch341_read_int_callback,
+ .attach = ch341_attach,
+};
+
+static int __init ch341_init(void)
+{
+ int retval;
+
+ retval = usb_serial_register(&ch341_device);
+ if (retval)
+ return retval;
+ retval = usb_register(&ch341_driver);
+ if (retval)
+ usb_serial_deregister(&ch341_device);
+ return retval;
+}
+
+static void __exit ch341_exit(void)
+{
+ usb_deregister(&ch341_driver);
+ usb_serial_deregister(&ch341_device);
+}
+
+module_init(ch341_init);
+module_exit(ch341_exit);
+MODULE_LICENSE("GPL");
+
+module_param(debug, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+
+/* EOF ch341.c */

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