iicbb.c revision 93023 
1/*-
2 * Copyright (c) 1998, 2001 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 93023 2002-03-23 15:49:15Z nsouch $
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 */
45
46#include <sys/param.h>
47#include <sys/kernel.h>
48#include <sys/systm.h>
49#include <sys/module.h>
50#include <sys/bus.h>
51#include <sys/uio.h>
52
53
54#include <dev/iicbus/iiconf.h>
55#include <dev/iicbus/iicbus.h>
56
57#include <dev/smbus/smbconf.h>
58
59#include "iicbus_if.h"
60#include "iicbb_if.h"
61
62struct iicbb_softc {
63	device_t iicbus;
64};
65
66static int iicbb_probe(device_t);
67static int iicbb_attach(device_t);
68static int iicbb_detach(device_t);
69static int iicbb_print_child(device_t, device_t);
70
71static int iicbb_callback(device_t, int, caddr_t);
72static int iicbb_start(device_t, u_char, int);
73static int iicbb_stop(device_t);
74static int iicbb_write(device_t, char *, int, int *, int);
75static int iicbb_read(device_t, char *, int, int *, int, int);
76static int iicbb_reset(device_t, u_char, u_char, u_char *);
77
78static device_method_t iicbb_methods[] = {
79	/* device interface */
80	DEVMETHOD(device_probe,		iicbb_probe),
81	DEVMETHOD(device_attach,	iicbb_attach),
82	DEVMETHOD(device_detach,	iicbb_detach),
83
84	/* bus interface */
85	DEVMETHOD(bus_print_child,	iicbb_print_child),
86
87	/* iicbus interface */
88	DEVMETHOD(iicbus_callback,	iicbb_callback),
89	DEVMETHOD(iicbus_start,		iicbb_start),
90	DEVMETHOD(iicbus_repeated_start, iicbb_start),
91	DEVMETHOD(iicbus_stop,		iicbb_stop),
92	DEVMETHOD(iicbus_write,		iicbb_write),
93	DEVMETHOD(iicbus_read,		iicbb_read),
94	DEVMETHOD(iicbus_reset,		iicbb_reset),
95
96	{ 0, 0 }
97};
98
99static driver_t iicbb_driver = {
100	"iicbb",
101	iicbb_methods,
102	sizeof(struct iicbb_softc),
103};
104
105static devclass_t iicbb_devclass;
106
107static int iicbb_probe(device_t dev)
108{
109	device_set_desc(dev, "I2C bit-banging driver");
110
111	return (0);
112}
113
114static int iicbb_attach(device_t dev)
115{
116	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
117
118	bzero(sc, sizeof(struct iicbb_softc));
119
120	sc->iicbus = device_add_child(dev, "iicbus", -1);
121
122	if (!sc->iicbus)
123		return (ENXIO);
124
125	bus_generic_attach(dev);
126
127	return (0);
128}
129
130static int iicbb_detach(device_t dev)
131{
132	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
133
134	if (sc->iicbus) {
135		bus_generic_detach(dev);
136		device_delete_child(dev, sc->iicbus);
137	}
138
139	return (0);
140}
141
142static int
143iicbb_print_child(device_t bus, device_t dev)
144{
145	int error;
146	int retval = 0;
147	u_char oldaddr;
148
149	retval += bus_print_child_header(bus, dev);
150	/* retrieve the interface I2C address */
151	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
152	if (error == IIC_ENOADDR) {
153		retval += printf(" on %s master-only\n",
154				 device_get_nameunit(bus));
155	} else {
156		/* restore the address */
157		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
158
159		retval += printf(" on %s addr 0x%x\n",
160				 device_get_nameunit(bus), oldaddr & 0xff);
161	}
162
163	return (retval);
164}
165
166#define IIC_DELAY	10
167
168#define I2C_SETSDA(dev,val) do {			\
169	IICBB_SETSDA(device_get_parent(dev), val);	\
170	DELAY(IIC_DELAY);				\
171	} while (0)
172
173#define I2C_SETSCL(dev,val) do {			\
174	iicbb_setscl(dev, val, 100);			\
175	} while (0)
176
177#define I2C_SET(dev,ctrl,data) do {			\
178	I2C_SETSCL(dev, ctrl);				\
179	I2C_SETSDA(dev, data);				\
180	} while (0)
181
182#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
183
184#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
185
186static int i2c_debug = 0;
187#define I2C_DEBUG(x)	do {					\
188				if (i2c_debug) (x);		\
189			} while (0)
190
191#define I2C_LOG(format,args...)	do {				\
192					printf(format, args);	\
193				} while (0)
194
195static void iicbb_setscl(device_t dev, int val, int timeout)
196{
197	int k = 0;
198
199	IICBB_SETSCL(device_get_parent(dev), val);
200	DELAY(IIC_DELAY);
201
202	while (val && !I2C_GETSCL(dev) && k++ < timeout) {
203		IICBB_SETSCL(device_get_parent(dev), val);
204		DELAY(IIC_DELAY);
205	}
206
207	return;
208}
209
210static void iicbb_one(device_t dev, int timeout)
211{
212	I2C_SET(dev,0,1);
213	I2C_SET(dev,1,1);
214	I2C_SET(dev,0,1);
215	return;
216}
217
218static void iicbb_zero(device_t dev, int timeout)
219{
220	I2C_SET(dev,0,0);
221	I2C_SET(dev,1,0);
222	I2C_SET(dev,0,0);
223	return;
224}
225
226/*
227 * Waiting for ACKNOWLEDGE.
228 *
229 * When a chip is being addressed or has received data it will issue an
230 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
231 * (set it to high level) and then release the CLOCK line.
232 * Now it must wait for the SLAVE to pull the DATA line low.
233 * Actually on the bus this looks like a START condition so nothing happens
234 * because of the fact that the IC's that have not been addressed are doing
235 * nothing.
236 *
237 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
238 * line low and then the SLAVE will release the SDA (data) line.
239 */
240static int iicbb_ack(device_t dev, int timeout)
241{
242	int noack;
243	int k = 0;
244
245	I2C_SET(dev,0,1);
246	I2C_SET(dev,1,1);
247	do {
248		noack = I2C_GETSDA(dev);
249		if (!noack)
250			break;
251		DELAY(10);
252		k += 10;
253	} while (k < timeout);
254
255	I2C_SET(dev,0,1);
256	I2C_DEBUG(printf("%c ",noack?'-':'+'));
257
258	return (noack);
259}
260
261static void iicbb_sendbyte(device_t dev, u_char data, int timeout)
262{
263	int i;
264
265	for (i=7; i>=0; i--) {
266		if (data&(1<<i)) {
267			iicbb_one(dev, timeout);
268		} else {
269			iicbb_zero(dev, timeout);
270		}
271	}
272	I2C_DEBUG(printf("w%02x",(int)data));
273	return;
274}
275
276static u_char iicbb_readbyte(device_t dev, int last, int timeout)
277{
278	int i;
279	unsigned char data=0;
280
281	I2C_SET(dev,0,1);
282	for (i=7; i>=0; i--)
283	{
284		I2C_SET(dev,1,1);
285		if (I2C_GETSDA(dev))
286			data |= (1<<i);
287		I2C_SET(dev,0,1);
288	}
289	if (last) {
290		iicbb_one(dev, timeout);
291	} else {
292		iicbb_zero(dev, timeout);
293	}
294	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
295	return data;
296}
297
298static int iicbb_callback(device_t dev, int index, caddr_t data)
299{
300	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
301}
302
303static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
304{
305	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
306}
307
308static int iicbb_start(device_t dev, u_char slave, int timeout)
309{
310	int error;
311
312	I2C_DEBUG(printf("<"));
313
314	I2C_SET(dev,1,1);
315	I2C_SET(dev,1,0);
316	I2C_SET(dev,0,0);
317
318	/* send address */
319	iicbb_sendbyte(dev, slave, timeout);
320
321	/* check for ack */
322	if (iicbb_ack(dev, timeout)) {
323		error = IIC_ENOACK;
324		goto error;
325	}
326
327	return(0);
328
329error:
330	iicbb_stop(dev);
331	return (error);
332}
333
334static int iicbb_stop(device_t dev)
335{
336	I2C_SET(dev,0,0);
337	I2C_SET(dev,1,0);
338	I2C_SET(dev,1,1);
339	I2C_DEBUG(printf(">"));
340	return (0);
341}
342
343static int iicbb_write(device_t dev, char * buf, int len, int *sent,
344			int timeout)
345{
346	int bytes, error = 0;
347
348	bytes = 0;
349	while (len) {
350		/* send byte */
351		iicbb_sendbyte(dev,(u_char)*buf++, timeout);
352
353		/* check for ack */
354		if (iicbb_ack(dev, timeout)) {
355			error = IIC_ENOACK;
356			goto error;
357		}
358		bytes ++;
359		len --;
360	}
361
362error:
363	*sent = bytes;
364	return (error);
365}
366
367static int iicbb_read(device_t dev, char * buf, int len, int *read,
368			int last, int delay)
369{
370	int bytes;
371
372	bytes = 0;
373	while (len) {
374		/* XXX should insert delay here */
375		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
376
377		bytes ++;
378		len --;
379	}
380
381	*read = bytes;
382	return (0);
383}
384
385DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0);
386DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
387DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
388
389MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
390MODULE_VERSION(iicbb, IICBB_MODVER);
391