iicbb.c revision 61722 
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 * $FreeBSD: head/sys/dev/iicbus/iicbb.c 61722 2000-06-16 07:20:29Z jake $
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/uio.h>
53
54#include <machine/clock.h>
55
56#include <dev/iicbus/iiconf.h>
57#include <dev/iicbus/iicbus.h>
58
59#include <dev/smbus/smbconf.h>
60
61#include "iicbus_if.h"
62#include "iicbb_if.h"
63
64struct iicbb_softc {
65	int dummy;
66};
67
68static int iicbb_probe(device_t);
69static int iicbb_attach(device_t);
70static int iicbb_print_child(device_t, device_t);
71
72static int iicbb_callback(device_t, int, caddr_t);
73static int iicbb_start(device_t, u_char, int);
74static int iicbb_stop(device_t);
75static int iicbb_write(device_t, char *, int, int *, int);
76static int iicbb_read(device_t, char *, int, int *, int, int);
77static int iicbb_reset(device_t, u_char, u_char, u_char *);
78
79static device_method_t iicbb_methods[] = {
80	/* device interface */
81	DEVMETHOD(device_probe,		iicbb_probe),
82	DEVMETHOD(device_attach,	iicbb_attach),
83	DEVMETHOD(device_detach,	bus_generic_detach),
84
85	/* bus interface */
86	DEVMETHOD(bus_print_child,	iicbb_print_child),
87
88	/* iicbus interface */
89	DEVMETHOD(iicbus_callback,	iicbb_callback),
90	DEVMETHOD(iicbus_start,		iicbb_start),
91	DEVMETHOD(iicbus_repeated_start, iicbb_start),
92	DEVMETHOD(iicbus_stop,		iicbb_stop),
93	DEVMETHOD(iicbus_write,		iicbb_write),
94	DEVMETHOD(iicbus_read,		iicbb_read),
95	DEVMETHOD(iicbus_reset,		iicbb_reset),
96
97	{ 0, 0 }
98};
99
100static driver_t iicbb_driver = {
101	"iicbb",
102	iicbb_methods,
103	sizeof(struct iicbb_softc),
104};
105
106static devclass_t iicbb_devclass;
107
108static int iicbb_probe(device_t dev)
109{
110	device_set_desc(dev, "I2C generic bit-banging driver");
111
112	return (0);
113}
114
115static int iicbb_attach(device_t dev)
116{
117	return (0);
118}
119
120static int
121iicbb_print_child(device_t bus, device_t dev)
122{
123	int error;
124	int retval = 0;
125	u_char oldaddr;
126
127	retval += bus_print_child_header(bus, dev);
128	/* retrieve the interface I2C address */
129	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
130	if (error == IIC_ENOADDR) {
131		retval += printf(" on %s master-only\n",
132				 device_get_nameunit(bus));
133	} else {
134		/* restore the address */
135		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
136
137		retval += printf(" on %s addr 0x%x\n",
138				 device_get_nameunit(bus), oldaddr & 0xff);
139	}
140
141	return (retval);
142}
143
144#define I2C_SET(dev,ctrl,data) \
145	IICBB_SETLINES(device_get_parent(dev), ctrl, data)
146
147#define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
148
149static int i2c_debug = 0;
150#define I2C_DEBUG(x) if (i2c_debug) (x)
151
152static void iicbb_one(device_t dev)
153{
154	I2C_SET(dev,0,1);
155	I2C_SET(dev,1,1);
156	I2C_SET(dev,0,1);
157	return;
158}
159
160static void iicbb_zero(device_t dev)
161{
162	I2C_SET(dev,0,0);
163	I2C_SET(dev,1,0);
164	I2C_SET(dev,0,0);
165	return;
166}
167
168/*
169 * Waiting for ACKNOWLEDGE.
170 *
171 * When a chip is being addressed or has received data it will issue an
172 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
173 * (set it to high level) and then release the CLOCK line.
174 * Now it must wait for the SLAVE to pull the DATA line low.
175 * Actually on the bus this looks like a START condition so nothing happens
176 * because of the fact that the IC's that have not been addressed are doing
177 * nothing.
178 *
179 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
180 * line low and then the SLAVE will release the SDA (data) line.
181 */
182static int iicbb_ack(device_t dev, int timeout)
183{
184	int noack;
185	int k = timeout/10;
186
187	I2C_SET(dev,0,1);
188	I2C_SET(dev,1,1);
189
190	do {
191		noack = I2C_GET(dev);
192		if (!noack)
193			break;
194		DELAY(10);		/* XXX wait 10us */
195	} while (k--);
196
197	I2C_SET(dev,0,1);
198	I2C_DEBUG(printf("%c ",noack?'-':'+'));
199
200	return (noack);
201}
202
203static void iicbb_sendbyte(device_t dev, u_char data)
204{
205	int i;
206
207	I2C_SET(dev,0,0);
208	for (i=7; i>=0; i--)
209		(data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
210	I2C_DEBUG(printf("w%02x",(int)data));
211	return;
212}
213
214static u_char iicbb_readbyte(device_t dev, int last)
215{
216	int i;
217	unsigned char data=0;
218
219	I2C_SET(dev,0,1);
220	for (i=7; i>=0; i--)
221	{
222		I2C_SET(dev,1,1);
223		if (I2C_GET(dev))
224			data |= (1<<i);
225		I2C_SET(dev,0,1);
226	}
227	last ? iicbb_one(dev) : iicbb_zero(dev);
228	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
229	return data;
230}
231
232static int iicbb_callback(device_t dev, int index, caddr_t data)
233{
234	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
235}
236
237static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
238{
239	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
240}
241
242static int iicbb_start(device_t dev, u_char slave, int timeout)
243{
244	int error;
245
246	I2C_DEBUG(printf("<"));
247
248	I2C_SET(dev,0,1);
249	I2C_SET(dev,1,1);
250	I2C_SET(dev,1,0);
251	I2C_SET(dev,0,0);
252
253	/* send address */
254	iicbb_sendbyte(dev, slave);
255
256	/* check for ack */
257	if (iicbb_ack(dev, timeout)) {
258		error = IIC_ENOACK;
259		goto error;
260	}
261
262	return(0);
263
264error:
265	iicbb_stop(dev);
266	return (error);
267}
268
269static int iicbb_stop(device_t dev)
270{
271	I2C_SET(dev,0,0);
272	I2C_SET(dev,1,0);
273	I2C_SET(dev,1,1);
274	I2C_DEBUG(printf(">"));
275	return (0);
276}
277
278static int iicbb_write(device_t dev, char * buf, int len, int *sent,
279			int timeout)
280{
281	int bytes, error = 0;
282
283	bytes = 0;
284	while (len) {
285		/* send byte */
286		iicbb_sendbyte(dev,(u_char)*buf++);
287
288		/* check for ack */
289		if (iicbb_ack(dev, timeout)) {
290			error = IIC_ENOACK;
291			goto error;
292		}
293		bytes ++;
294		len --;
295	}
296
297error:
298	*sent = bytes;
299	return (error);
300}
301
302static int iicbb_read(device_t dev, char * buf, int len, int *read,
303			int last, int delay)
304{
305	int bytes;
306
307	bytes = 0;
308	while (len) {
309		/* XXX should insert delay here */
310		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
311
312		bytes ++;
313		len --;
314	}
315
316	*read = bytes;
317	return (0);
318}
319
320DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
321DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
322