ch341.c revision 6ce76104781a10554129791dc62c3104424f6d48 
1/*
2 * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
3 *
4 * ch341.c implements a serial port driver for the Winchiphead CH341.
5 *
6 * The CH341 device can be used to implement an RS232 asynchronous
7 * serial port, an IEEE-1284 parallel printer port or a memory-like
8 * interface. In all cases the CH341 supports an I2C interface as well.
9 * This driver only supports the asynchronous serial interface.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License version
13 * 2 as published by the Free Software Foundation.
14 */
15
16#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/tty.h>
19#include <linux/module.h>
20#include <linux/usb.h>
21#include <linux/usb/serial.h>
22#include <linux/serial.h>
23
24#define DEFAULT_BAUD_RATE 2400
25#define DEFAULT_TIMEOUT   1000
26
27static int debug;
28
29static struct usb_device_id id_table [] = {
30	{ USB_DEVICE(0x4348, 0x5523) },
31	{ },
32};
33MODULE_DEVICE_TABLE(usb, id_table);
34
35struct ch341_private {
36	unsigned baud_rate;
37	u8 dtr;
38	u8 rts;
39};
40
41static int ch341_control_out(struct usb_device *dev, u8 request,
42			     u16 value, u16 index)
43{
44	int r;
45	dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
46		(int)request, (int)value, (int)index);
47
48	r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
49			    USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
50			    value, index, NULL, 0, DEFAULT_TIMEOUT);
51
52	return r;
53}
54
55static int ch341_control_in(struct usb_device *dev,
56			    u8 request, u16 value, u16 index,
57			    char *buf, unsigned bufsize)
58{
59	int r;
60	dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
61		(int)request, (int)value, (int)index, buf, (int)bufsize);
62
63	r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
64			    USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
65			    value, index, buf, bufsize, DEFAULT_TIMEOUT);
66	return r;
67}
68
69int ch341_set_baudrate(struct usb_device *dev, struct ch341_private *priv)
70{
71	short a, b;
72	int r;
73
74	dbg("ch341_set_baudrate(%d)", priv->baud_rate);
75	switch (priv->baud_rate) {
76	case 2400:
77		a = 0xd901;
78		b = 0x0038;
79		break;
80	case 4800:
81		a = 0x6402;
82		b = 0x001f;
83		break;
84	case 9600:
85		a = 0xb202;
86		b = 0x0013;
87		break;
88	case 19200:
89		a = 0xd902;
90		b = 0x000d;
91		break;
92	case 38400:
93		a = 0x6403;
94		b = 0x000a;
95		break;
96	case 115200:
97		a = 0xcc03;
98		b = 0x0008;
99		break;
100	default:
101		return -EINVAL;
102	}
103
104	r = ch341_control_out(dev, 0x9a, 0x1312, a);
105	if (!r)
106		r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
107
108	return r;
109}
110
111int ch341_set_handshake(struct usb_device *dev, struct ch341_private *priv)
112{
113	dbg("ch341_set_handshake(%d,%d)", priv->dtr, priv->rts);
114	return ch341_control_out(dev, 0xa4,
115		~((priv->dtr?1<<5:0)|(priv->rts?1<<6:0)), 0);
116}
117
118int ch341_get_status(struct usb_device *dev)
119{
120	char *buffer;
121	int r;
122	const unsigned size = 8;
123
124	dbg("ch341_get_status()");
125
126	buffer = kmalloc(size, GFP_KERNEL);
127	if (!buffer)
128		return -ENOMEM;
129
130	r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
131	if ( r < 0)
132		goto out;
133
134	/* Not having the datasheet for the CH341, we ignore the bytes returned
135	 * from the device. Return error if the device did not respond in time.
136	 */
137	r = 0;
138
139out:	kfree(buffer);
140	return r;
141}
142
143/* -------------------------------------------------------------------------- */
144
145int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
146{
147	char *buffer;
148	int r;
149	const unsigned size = 8;
150
151	dbg("ch341_configure()");
152
153	buffer = kmalloc(size, GFP_KERNEL);
154	if (!buffer)
155		return -ENOMEM;
156
157	/* expect two bytes 0x27 0x00 */
158	r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
159	if (r < 0)
160		goto out;
161
162	r = ch341_control_out(dev, 0xa1, 0, 0);
163	if (r < 0)
164		goto out;
165
166	r = ch341_set_baudrate(dev, priv);
167	if (r < 0)
168		goto out;
169
170	/* expect two bytes 0x56 0x00 */
171	r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
172	if (r < 0)
173		goto out;
174
175	r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
176	if (r < 0)
177		goto out;
178
179	/* expect 0xff 0xee */
180	r = ch341_get_status(dev);
181	if (r < 0)
182		goto out;
183
184	r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
185	if (r < 0)
186		goto out;
187
188	r = ch341_set_baudrate(dev, priv);
189	if (r < 0)
190		goto out;
191
192	r = ch341_set_handshake(dev, priv);
193	if (r < 0)
194		goto out;
195
196	/* expect 0x9f 0xee */
197	r = ch341_get_status(dev);
198
199out:	kfree(buffer);
200	return r;
201}
202
203/* allocate private data */
204static int ch341_attach(struct usb_serial *serial)
205{
206	struct ch341_private *priv;
207	int r;
208
209	dbg("ch341_attach()");
210
211	/* private data */
212	priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
213	if (!priv)
214		return -ENOMEM;
215
216	priv->baud_rate = DEFAULT_BAUD_RATE;
217	priv->dtr = 1;
218	priv->rts = 1;
219
220	r = ch341_configure(serial->dev, priv);
221	if (r < 0)
222		goto error;
223
224	usb_set_serial_port_data(serial->port[0], priv);
225	return 0;
226
227error:	kfree(priv);
228	return r;
229}
230
231/* open this device, set default parameters */
232static int ch341_open(struct usb_serial_port *port, struct file *filp)
233{
234	struct usb_serial *serial = port->serial;
235	struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
236	int r;
237
238	dbg("ch341_open()");
239
240	priv->baud_rate = DEFAULT_BAUD_RATE;
241	priv->dtr = 1;
242	priv->rts = 1;
243
244	r = ch341_configure(serial->dev, priv);
245	if (r)
246		goto out;
247
248	r = ch341_set_handshake(serial->dev, priv);
249	if (r)
250		goto out;
251
252	r = ch341_set_baudrate(serial->dev, priv);
253	if (r)
254		goto out;
255
256	r = usb_serial_generic_open(port, filp);
257
258out:	return r;
259}
260
261/* Old_termios contains the original termios settings and
262 * tty->termios contains the new setting to be used.
263 */
264static void ch341_set_termios(struct usb_serial_port *port,
265			      struct ktermios *old_termios)
266{
267	struct ch341_private *priv = usb_get_serial_port_data(port);
268	struct tty_struct *tty = port->tty;
269	unsigned baud_rate;
270
271	dbg("ch341_set_termios()");
272
273	if (!tty || !tty->termios)
274		return;
275
276	baud_rate = tty_get_baud_rate(tty);
277
278	switch (baud_rate) {
279	case 2400:
280	case 4800:
281	case 9600:
282	case 19200:
283	case 38400:
284	case 115200:
285		priv->baud_rate = baud_rate;
286		break;
287	default:
288		dbg("Rate %d not supported, using %d",
289			baud_rate, DEFAULT_BAUD_RATE);
290		priv->baud_rate = DEFAULT_BAUD_RATE;
291	}
292
293	ch341_set_baudrate(port->serial->dev, priv);
294
295	/* Unimplemented:
296	 * (cflag & CSIZE) : data bits [5, 8]
297	 * (cflag & PARENB) : parity {NONE, EVEN, ODD}
298	 * (cflag & CSTOPB) : stop bits [1, 2]
299	 */
300}
301
302static struct usb_driver ch341_driver = {
303	.name		= "ch341",
304	.probe		= usb_serial_probe,
305	.disconnect	= usb_serial_disconnect,
306	.id_table	= id_table,
307	.no_dynamic_id	= 1,
308};
309
310static struct usb_serial_driver ch341_device = {
311	.driver = {
312		.owner	= THIS_MODULE,
313		.name	= "ch341-uart",
314	},
315	.id_table         = id_table,
316	.usb_driver       = &ch341_driver,
317	.num_interrupt_in = NUM_DONT_CARE,
318	.num_bulk_in      = 1,
319	.num_bulk_out     = 1,
320	.num_ports        = 1,
321	.open             = ch341_open,
322	.set_termios      = ch341_set_termios,
323	.attach           = ch341_attach,
324};
325
326static int __init ch341_init(void)
327{
328	int retval;
329
330	retval = usb_serial_register(&ch341_device);
331	if (retval)
332		return retval;
333	retval = usb_register(&ch341_driver);
334	if (retval)
335		usb_serial_deregister(&ch341_device);
336	return retval;
337}
338
339static void __exit ch341_exit(void)
340{
341	usb_deregister(&ch341_driver);
342	usb_serial_deregister(&ch341_device);
343}
344
345module_init(ch341_init);
346module_exit(ch341_exit);
347MODULE_LICENSE("GPL");
348
349module_param(debug, bool, S_IRUGO | S_IWUSR);
350MODULE_PARM_DESC(debug, "Debug enabled or not");
351
352/* EOF ch341.c */
353