iicbb.c revision 157523 
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
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/dev/iicbus/iicbb.c 157523 2006-04-04 23:29:17Z imp $");
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
99driver_t iicbb_driver = {
100	"iicbb",
101	iicbb_methods,
102	sizeof(struct iicbb_softc),
103};
104
105devclass_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	sc->iicbus = device_add_child(dev, "iicbus", -1);
119	if (!sc->iicbus)
120		return (ENXIO);
121	bus_generic_attach(dev);
122
123	return (0);
124}
125
126static int iicbb_detach(device_t dev)
127{
128	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
129
130	if (sc->iicbus) {
131		bus_generic_detach(dev);
132		device_delete_child(dev, sc->iicbus);
133	}
134
135	return (0);
136}
137
138static int
139iicbb_print_child(device_t bus, device_t dev)
140{
141	int error;
142	int retval = 0;
143	u_char oldaddr;
144
145	retval += bus_print_child_header(bus, dev);
146	/* retrieve the interface I2C address */
147	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
148	if (error == IIC_ENOADDR) {
149		retval += printf(" on %s master-only\n",
150				 device_get_nameunit(bus));
151	} else {
152		/* restore the address */
153		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
154
155		retval += printf(" on %s addr 0x%x\n",
156				 device_get_nameunit(bus), oldaddr & 0xff);
157	}
158
159	return (retval);
160}
161
162#define IIC_DELAY	10
163
164#define I2C_SETSDA(dev,val) do {			\
165	IICBB_SETSDA(device_get_parent(dev), val);	\
166	DELAY(IIC_DELAY);				\
167	} while (0)
168
169#define I2C_SETSCL(dev,val) do {			\
170	iicbb_setscl(dev, val, 100);			\
171	} while (0)
172
173#define I2C_SET(dev,ctrl,data) do {			\
174	I2C_SETSCL(dev, ctrl);				\
175	I2C_SETSDA(dev, data);				\
176	} while (0)
177
178#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
179
180#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
181
182static int i2c_debug = 0;
183#define I2C_DEBUG(x)	do {					\
184				if (i2c_debug) (x);		\
185			} while (0)
186
187#define I2C_LOG(format,args...)	do {				\
188					printf(format, args);	\
189				} while (0)
190
191static void iicbb_setscl(device_t dev, int val, int timeout)
192{
193	int k = 0;
194
195	IICBB_SETSCL(device_get_parent(dev), val);
196	DELAY(IIC_DELAY);
197
198	while (val && !I2C_GETSCL(dev) && k++ < timeout) {
199		IICBB_SETSCL(device_get_parent(dev), val);
200		DELAY(IIC_DELAY);
201	}
202
203	return;
204}
205
206static void iicbb_one(device_t dev, int timeout)
207{
208	I2C_SET(dev,0,1);
209	I2C_SET(dev,1,1);
210	I2C_SET(dev,0,1);
211	return;
212}
213
214static void iicbb_zero(device_t dev, int timeout)
215{
216	I2C_SET(dev,0,0);
217	I2C_SET(dev,1,0);
218	I2C_SET(dev,0,0);
219	return;
220}
221
222/*
223 * Waiting for ACKNOWLEDGE.
224 *
225 * When a chip is being addressed or has received data it will issue an
226 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
227 * (set it to high level) and then release the CLOCK line.
228 * Now it must wait for the SLAVE to pull the DATA line low.
229 * Actually on the bus this looks like a START condition so nothing happens
230 * because of the fact that the IC's that have not been addressed are doing
231 * nothing.
232 *
233 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
234 * line low and then the SLAVE will release the SDA (data) line.
235 */
236static int iicbb_ack(device_t dev, int timeout)
237{
238	int noack;
239	int k = 0;
240
241	I2C_SET(dev,0,1);
242	I2C_SET(dev,1,1);
243	do {
244		noack = I2C_GETSDA(dev);
245		if (!noack)
246			break;
247		DELAY(10);
248		k += 10;
249	} while (k < timeout);
250
251	I2C_SET(dev,0,1);
252	I2C_DEBUG(printf("%c ",noack?'-':'+'));
253
254	return (noack);
255}
256
257static void iicbb_sendbyte(device_t dev, u_char data, int timeout)
258{
259	int i;
260
261	for (i=7; i>=0; i--) {
262		if (data&(1<<i)) {
263			iicbb_one(dev, timeout);
264		} else {
265			iicbb_zero(dev, timeout);
266		}
267	}
268	I2C_DEBUG(printf("w%02x",(int)data));
269	return;
270}
271
272static u_char iicbb_readbyte(device_t dev, int last, int timeout)
273{
274	int i;
275	unsigned char data=0;
276
277	I2C_SET(dev,0,1);
278	for (i=7; i>=0; i--)
279	{
280		I2C_SET(dev,1,1);
281		if (I2C_GETSDA(dev))
282			data |= (1<<i);
283		I2C_SET(dev,0,1);
284	}
285	if (last) {
286		iicbb_one(dev, timeout);
287	} else {
288		iicbb_zero(dev, timeout);
289	}
290	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
291	return data;
292}
293
294static int iicbb_callback(device_t dev, int index, caddr_t data)
295{
296	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
297}
298
299static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
300{
301	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
302}
303
304static int iicbb_start(device_t dev, u_char slave, int timeout)
305{
306	int error;
307
308	I2C_DEBUG(printf("<"));
309
310	I2C_SET(dev,1,1);
311	I2C_SET(dev,1,0);
312	I2C_SET(dev,0,0);
313
314	/* send address */
315	iicbb_sendbyte(dev, slave, timeout);
316
317	/* check for ack */
318	if (iicbb_ack(dev, timeout)) {
319		error = IIC_ENOACK;
320		goto error;
321	}
322
323	return(0);
324
325error:
326	iicbb_stop(dev);
327	return (error);
328}
329
330static int iicbb_stop(device_t dev)
331{
332	I2C_SET(dev,0,0);
333	I2C_SET(dev,1,0);
334	I2C_SET(dev,1,1);
335	I2C_DEBUG(printf(">"));
336	return (0);
337}
338
339static int iicbb_write(device_t dev, char * buf, int len, int *sent,
340			int timeout)
341{
342	int bytes, error = 0;
343
344	bytes = 0;
345	while (len) {
346		/* send byte */
347		iicbb_sendbyte(dev,(u_char)*buf++, timeout);
348
349		/* check for ack */
350		if (iicbb_ack(dev, timeout)) {
351			error = IIC_ENOACK;
352			goto error;
353		}
354		bytes ++;
355		len --;
356	}
357
358error:
359	*sent = bytes;
360	return (error);
361}
362
363static int iicbb_read(device_t dev, char * buf, int len, int *read,
364			int last, int delay)
365{
366	int bytes;
367
368	bytes = 0;
369	while (len) {
370		/* XXX should insert delay here */
371		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
372
373		bytes ++;
374		len --;
375	}
376
377	*read = bytes;
378	return (0);
379}
380
381DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0);
382DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
383DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
384
385MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
386MODULE_VERSION(iicbb, IICBB_MODVER);
387