/*
* 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;
}
static 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;
}
static 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);
}
static 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;
}
/* -------------------------------------------------------------------------- */
static 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()");
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]
*/
/* Copy back the old hardware settings */
tty_termios_copy_hw(tty->termios, old_termios);
/* And re-encode with the new baud */
tty_encode_baud_rate(tty, baud_rate, baud_rate);
}
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 */
