--- /dev/null
+/*
+ * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
+ *
+ * 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 2400
+#define DEFAULT_TIMEOUT 1000
+
+static int debug;
+
+static struct usb_device_id id_table [] = {
+ { USB_DEVICE(0x4348, 0x5523) },
+ { },
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+struct ch341_private {
+ unsigned baud_rate;
+ u8 dtr;
+ u8 rts;
+};
+
+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;
+
+ dbg("ch341_set_baudrate(%d)", priv->baud_rate);
+ switch (priv->baud_rate) {
+ case 2400:
+ a = 0xd901;
+ b = 0x0038;
+ break;
+ case 4800:
+ a = 0x6402;
+ b = 0x001f;
+ break;
+ case 9600:
+ a = 0xb202;
+ b = 0x0013;
+ break;
+ case 19200:
+ a = 0xd902;
+ b = 0x000d;
+ break;
+ case 38400:
+ a = 0x6403;
+ b = 0x000a;
+ break;
+ case 115200:
+ a = 0xcc03;
+ b = 0x0008;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ 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, struct ch341_private *priv)
+{
+ dbg("ch341_set_handshake(%d,%d)", priv->dtr, priv->rts);
+ return ch341_control_out(dev, 0xa4,
+ ~((priv->dtr?1<<5:0)|(priv->rts?1<<6:0)), 0);
+}
+
+int ch341_get_status(struct usb_device *dev)
+{
+ char *buffer;
+ int r;
+ const unsigned size = 8;
+
+ 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;
+
+ /* Not having the datasheet for the CH341, we ignore the bytes returned
+ * from the device. Return error if the device did not respond in time.
+ */
+ r = 0;
+
+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);
+ 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);
+ if (r < 0)
+ goto out;
+
+ /* expect 0x9f 0xee */
+ r = ch341_get_status(dev);
+
+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;
+
+ priv->baud_rate = DEFAULT_BAUD_RATE;
+ priv->dtr = 1;
+ priv->rts = 1;
+
+ 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;
+}
+
+/* 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->dtr = 1;
+ priv->rts = 1;
+
+ r = ch341_configure(serial->dev, priv);
+ if (r)
+ goto out;
+
+ r = ch341_set_handshake(serial->dev, priv);
+ if (r)
+ goto out;
+
+ r = ch341_set_baudrate(serial->dev, priv);
+ if (r)
+ goto out;
+
+ 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;
+
+ dbg("ch341_set_termios()");
+
+ if (!tty || !tty->termios)
+ return;
+
+ baud_rate = tty_get_baud_rate(tty);
+
+ switch (baud_rate) {
+ case 2400:
+ case 4800:
+ case 9600:
+ case 19200:
+ case 38400:
+ case 115200:
+ priv->baud_rate = baud_rate;
+ break;
+ default:
+ dbg("Rate %d not supported, using %d",
+ baud_rate, DEFAULT_BAUD_RATE);
+ priv->baud_rate = DEFAULT_BAUD_RATE;
+ }
+
+ ch341_set_baudrate(port->serial->dev, priv);
+
+ /* Unimplemented:
+ * (cflag & CSIZE) : data bits [5, 8]
+ * (cflag & PARENB) : parity {NONE, EVEN, ODD}
+ * (cflag & CSTOPB) : stop bits [1, 2]
+ */
+}
+
+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 = NUM_DONT_CARE,
+ .num_bulk_in = 1,
+ .num_bulk_out = 1,
+ .num_ports = 1,
+ .open = ch341_open,
+ .set_termios = ch341_set_termios,
+ .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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