iicbb.c revision 46743 
1/*-
2 * Copyright (c) 1998 Nicolas Souchu
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 *	$Id: iicbb.c,v 1.3 1999/01/28 15:50:24 roger Exp $
27 *
28 */
29
30/*
31 * Generic I2C bit-banging code
32 *
33 * Example:
34 *
35 *	iicbus
36 *	 /  \
37 *    iicbb pcf
38 *     |  \
39 *   bti2c lpbb
40 *
41 * From Linux I2C generic interface
42 * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
43 *
44 * TODO: port Peter's generic bit-banging code <dufault@hda.com>
45 */
46
47#include <sys/param.h>
48#include <sys/kernel.h>
49#include <sys/systm.h>
50#include <sys/module.h>
51#include <sys/bus.h>
52#include <sys/conf.h>
53#include <sys/buf.h>
54#include <sys/uio.h>
55#include <sys/malloc.h>
56
57#include <machine/clock.h>
58
59#include <dev/iicbus/iiconf.h>
60#include <dev/iicbus/iicbus.h>
61
62#include <dev/smbus/smbconf.h>
63
64#include "iicbus_if.h"
65#include "iicbb_if.h"
66
67struct iicbb_softc {
68	int dummy;
69};
70
71static int iicbb_probe(device_t);
72static int iicbb_attach(device_t);
73static void iicbb_print_child(device_t, device_t);
74
75static int iicbb_callback(device_t, int, caddr_t);
76static int iicbb_start(device_t, u_char, int);
77static int iicbb_stop(device_t);
78static int iicbb_write(device_t, char *, int, int *, int);
79static int iicbb_read(device_t, char *, int, int *, int, int);
80static int iicbb_reset(device_t, u_char, u_char, u_char *);
81
82static device_method_t iicbb_methods[] = {
83	/* device interface */
84	DEVMETHOD(device_probe,		iicbb_probe),
85	DEVMETHOD(device_attach,	iicbb_attach),
86
87	/* bus interface */
88	DEVMETHOD(bus_print_child,	iicbb_print_child),
89
90	/* iicbus interface */
91	DEVMETHOD(iicbus_callback,	iicbb_callback),
92	DEVMETHOD(iicbus_start,		iicbb_start),
93	DEVMETHOD(iicbus_repeated_start, iicbb_start),
94	DEVMETHOD(iicbus_stop,		iicbb_stop),
95	DEVMETHOD(iicbus_write,		iicbb_write),
96	DEVMETHOD(iicbus_read,		iicbb_read),
97	DEVMETHOD(iicbus_reset,		iicbb_reset),
98
99	{ 0, 0 }
100};
101
102static driver_t iicbb_driver = {
103	"iicbb",
104	iicbb_methods,
105	sizeof(struct iicbb_softc),
106};
107
108static devclass_t iicbb_devclass;
109
110static int iicbb_probe(device_t dev)
111{
112	device_set_desc(dev, "I2C generic bit-banging driver");
113
114	return (0);
115}
116
117static int iicbb_attach(device_t dev)
118{
119	return (0);
120}
121
122static void
123iicbb_print_child(device_t bus, device_t dev)
124{
125	int error;
126	u_char oldaddr;
127
128	/* retrieve the interface I2C address */
129	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
130	if (error == IIC_ENOADDR) {
131		printf(" on %s%d master-only", device_get_name(bus),
132			device_get_unit(bus));
133
134	} else {
135		/* restore the address */
136		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
137
138		printf(" on %s%d addr 0x%x", device_get_name(bus),
139			device_get_unit(bus), oldaddr & 0xff);
140	}
141
142	return;
143}
144
145#define I2C_SET(dev,ctrl,data) \
146	IICBB_SETLINES(device_get_parent(dev), ctrl, data)
147
148#define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
149
150static int i2c_debug = 0;
151#define I2C_DEBUG(x) if (i2c_debug) (x)
152
153static void iicbb_one(device_t dev)
154{
155	I2C_SET(dev,0,1);
156	I2C_SET(dev,1,1);
157	I2C_SET(dev,0,1);
158	return;
159}
160
161static void iicbb_zero(device_t dev)
162{
163	I2C_SET(dev,0,0);
164	I2C_SET(dev,1,0);
165	I2C_SET(dev,0,0);
166	return;
167}
168
169/*
170 * Waiting for ACKNOWLEDGE.
171 *
172 * When a chip is being addressed or has received data it will issue an
173 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
174 * (set it to high level) and then release the CLOCK line.
175 * Now it must wait for the SLAVE to pull the DATA line low.
176 * Actually on the bus this looks like a START condition so nothing happens
177 * because of the fact that the IC's that have not been addressed are doing
178 * nothing.
179 *
180 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
181 * line low and then the SLAVE will release the SDA (data) line.
182 */
183static int iicbb_ack(device_t dev, int timeout)
184{
185	int noack;
186	int k = timeout/10;
187
188	I2C_SET(dev,0,1);
189	I2C_SET(dev,1,1);
190
191	do {
192		noack = I2C_GET(dev);
193		if (!noack)
194			break;
195		DELAY(10);		/* XXX wait 10us */
196	} while (k--);
197
198	I2C_SET(dev,0,1);
199	I2C_DEBUG(printf("%c ",noack?'-':'+'));
200
201	return (noack);
202}
203
204static void iicbb_sendbyte(device_t dev, u_char data)
205{
206	int i;
207
208	I2C_SET(dev,0,0);
209	for (i=7; i>=0; i--)
210		(data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
211	I2C_DEBUG(printf("w%02x",(int)data));
212	return;
213}
214
215static u_char iicbb_readbyte(device_t dev, int last)
216{
217	int i;
218	unsigned char data=0;
219
220	I2C_SET(dev,0,1);
221	for (i=7; i>=0; i--)
222	{
223		I2C_SET(dev,1,1);
224		if (I2C_GET(dev))
225			data |= (1<<i);
226		I2C_SET(dev,0,1);
227	}
228	last ? iicbb_one(dev) : iicbb_zero(dev);
229	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
230	return data;
231}
232
233static int iicbb_callback(device_t dev, int index, caddr_t data)
234{
235	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
236}
237
238static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
239{
240	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
241}
242
243static int iicbb_start(device_t dev, u_char slave, int timeout)
244{
245	int error;
246
247	I2C_DEBUG(printf("<"));
248
249	I2C_SET(dev,0,1);
250	I2C_SET(dev,1,1);
251	I2C_SET(dev,1,0);
252	I2C_SET(dev,0,0);
253
254	/* send address */
255	iicbb_sendbyte(dev, slave);
256
257	/* check for ack */
258	if (iicbb_ack(dev, timeout)) {
259		error = IIC_ENOACK;
260		goto error;
261	}
262
263	return(0);
264
265error:
266	iicbb_stop(dev);
267	return (error);
268}
269
270static int iicbb_stop(device_t dev)
271{
272	I2C_SET(dev,0,0);
273	I2C_SET(dev,1,0);
274	I2C_SET(dev,1,1);
275	I2C_DEBUG(printf(">"));
276	return (0);
277}
278
279static int iicbb_write(device_t dev, char * buf, int len, int *sent,
280			int timeout)
281{
282	int bytes, error = 0;
283
284	bytes = 0;
285	while (len) {
286		/* send byte */
287		iicbb_sendbyte(dev,(u_char)*buf++);
288
289		/* check for ack */
290		if (iicbb_ack(dev, timeout)) {
291			error = IIC_ENOACK;
292			goto error;
293		}
294		bytes ++;
295		len --;
296	}
297
298error:
299	*sent = bytes;
300	return (error);
301}
302
303static int iicbb_read(device_t dev, char * buf, int len, int *read,
304			int last, int delay)
305{
306	int bytes;
307
308	bytes = 0;
309	while (len) {
310		/* XXX should insert delay here */
311		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
312
313		bytes ++;
314		len --;
315	}
316
317	*read = bytes;
318	return (0);
319}
320
321DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
322DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
323