iicbb.c revision 164900 
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 164900 2006-12-05 06:11:10Z 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_attach(device_t);
67static void iicbb_child_detached(device_t, device_t);
68static int iicbb_detach(device_t);
69static int iicbb_print_child(device_t, device_t);
70static int iicbb_probe(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,	iicbb_detach),
84
85	/* bus interface */
86	DEVMETHOD(bus_child_detached,	iicbb_child_detached),
87	DEVMETHOD(bus_print_child,	iicbb_print_child),
88
89	/* iicbus interface */
90	DEVMETHOD(iicbus_callback,	iicbb_callback),
91	DEVMETHOD(iicbus_start,		iicbb_start),
92	DEVMETHOD(iicbus_repeated_start, iicbb_start),
93	DEVMETHOD(iicbus_stop,		iicbb_stop),
94	DEVMETHOD(iicbus_write,		iicbb_write),
95	DEVMETHOD(iicbus_read,		iicbb_read),
96	DEVMETHOD(iicbus_reset,		iicbb_reset),
97
98	{ 0, 0 }
99};
100
101driver_t iicbb_driver = {
102	"iicbb",
103	iicbb_methods,
104	sizeof(struct iicbb_softc),
105};
106
107devclass_t iicbb_devclass;
108
109static int
110iicbb_probe(device_t dev)
111{
112	device_set_desc(dev, "I2C bit-banging driver");
113
114	return (0);
115}
116
117static int
118iicbb_attach(device_t dev)
119{
120	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
121
122	sc->iicbus = device_add_child(dev, "iicbus", -1);
123	if (!sc->iicbus)
124		return (ENXIO);
125	bus_generic_attach(dev);
126
127	return (0);
128}
129
130static int
131iicbb_detach(device_t dev)
132{
133	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
134	device_t child;
135
136	/*
137	 * We need to save child because the detach indirectly causes
138	 * sc->iicbus to be zeroed.  Since we added the device
139	 * unconditionally in iicbb_attach, we need to make sure we
140	 * delete it here.  See iicbb_child_detached.  We need that
141	 * callback in case newbus detached our children w/o detaching
142	 * us (say iicbus is a module and unloaded w/o iicbb being
143	 * unloaded).
144	 */
145	child = sc->iicbus;
146	bus_generic_detach(dev);
147	if (child)
148		device_delete_child(dev, child);
149
150	return (0);
151}
152
153static void
154iicbb_child_detached( device_t dev, device_t child )
155{
156	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
157
158	if (child == sc->iicbus)
159		sc->iicbus = NULL;
160}
161
162static int
163iicbb_print_child(device_t bus, device_t dev)
164{
165	int error;
166	int retval = 0;
167	u_char oldaddr;
168
169	retval += bus_print_child_header(bus, dev);
170	/* retrieve the interface I2C address */
171	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
172	if (error == IIC_ENOADDR) {
173		retval += printf(" on %s master-only\n",
174				 device_get_nameunit(bus));
175	} else {
176		/* restore the address */
177		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
178
179		retval += printf(" on %s addr 0x%x\n",
180				 device_get_nameunit(bus), oldaddr & 0xff);
181	}
182
183	return (retval);
184}
185
186#define IIC_DELAY	10
187
188#define I2C_SETSDA(dev,val) do {			\
189	IICBB_SETSDA(device_get_parent(dev), val);	\
190	DELAY(IIC_DELAY);				\
191	} while (0)
192
193#define I2C_SETSCL(dev,val) do {			\
194	iicbb_setscl(dev, val, 100);			\
195	} while (0)
196
197#define I2C_SET(dev,ctrl,data) do {			\
198	I2C_SETSCL(dev, ctrl);				\
199	I2C_SETSDA(dev, data);				\
200	} while (0)
201
202#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
203
204#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
205
206static int i2c_debug = 0;
207#define I2C_DEBUG(x)	do {					\
208				if (i2c_debug) (x);		\
209			} while (0)
210
211#define I2C_LOG(format,args...)	do {				\
212					printf(format, args);	\
213				} while (0)
214
215static void
216iicbb_setscl(device_t dev, int val, int timeout)
217{
218	int k = 0;
219
220	IICBB_SETSCL(device_get_parent(dev), val);
221	DELAY(IIC_DELAY);
222
223	while (val && !I2C_GETSCL(dev) && k++ < timeout) {
224		IICBB_SETSCL(device_get_parent(dev), val);
225		DELAY(IIC_DELAY);
226	}
227
228	return;
229}
230
231static void
232iicbb_one(device_t dev, int timeout)
233{
234	I2C_SET(dev,0,1);
235	I2C_SET(dev,1,1);
236	I2C_SET(dev,0,1);
237	return;
238}
239
240static void
241iicbb_zero(device_t dev, int timeout)
242{
243	I2C_SET(dev,0,0);
244	I2C_SET(dev,1,0);
245	I2C_SET(dev,0,0);
246	return;
247}
248
249/*
250 * Waiting for ACKNOWLEDGE.
251 *
252 * When a chip is being addressed or has received data it will issue an
253 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
254 * (set it to high level) and then release the CLOCK line.
255 * Now it must wait for the SLAVE to pull the DATA line low.
256 * Actually on the bus this looks like a START condition so nothing happens
257 * because of the fact that the IC's that have not been addressed are doing
258 * nothing.
259 *
260 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
261 * line low and then the SLAVE will release the SDA (data) line.
262 */
263static int
264iicbb_ack(device_t dev, int timeout)
265{
266	int noack;
267	int k = 0;
268
269	I2C_SET(dev,0,1);
270	I2C_SET(dev,1,1);
271	do {
272		noack = I2C_GETSDA(dev);
273		if (!noack)
274			break;
275		DELAY(10);
276		k += 10;
277	} while (k < timeout);
278
279	I2C_SET(dev,0,1);
280	I2C_DEBUG(printf("%c ",noack?'-':'+'));
281
282	return (noack);
283}
284
285static void
286iicbb_sendbyte(device_t dev, u_char data, int timeout)
287{
288	int i;
289
290	for (i=7; i>=0; i--) {
291		if (data&(1<<i)) {
292			iicbb_one(dev, timeout);
293		} else {
294			iicbb_zero(dev, timeout);
295		}
296	}
297	I2C_DEBUG(printf("w%02x",(int)data));
298	return;
299}
300
301static u_char
302iicbb_readbyte(device_t dev, int last, int timeout)
303{
304	int i;
305	unsigned char data=0;
306
307	I2C_SET(dev,0,1);
308	for (i=7; i>=0; i--)
309	{
310		I2C_SET(dev,1,1);
311		if (I2C_GETSDA(dev))
312			data |= (1<<i);
313		I2C_SET(dev,0,1);
314	}
315	if (last) {
316		iicbb_one(dev, timeout);
317	} else {
318		iicbb_zero(dev, timeout);
319	}
320	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
321	return data;
322}
323
324static int
325iicbb_callback(device_t dev, int index, caddr_t data)
326{
327	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
328}
329
330static int
331iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
332{
333	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
334}
335
336static int
337iicbb_start(device_t dev, u_char slave, int timeout)
338{
339	int error;
340
341	I2C_DEBUG(printf("<"));
342
343	I2C_SET(dev,1,1);
344	I2C_SET(dev,1,0);
345	I2C_SET(dev,0,0);
346
347	/* send address */
348	iicbb_sendbyte(dev, slave, timeout);
349
350	/* check for ack */
351	if (iicbb_ack(dev, timeout)) {
352		error = IIC_ENOACK;
353		goto error;
354	}
355
356	return(0);
357
358error:
359	iicbb_stop(dev);
360	return (error);
361}
362
363static int
364iicbb_stop(device_t dev)
365{
366	I2C_SET(dev,0,0);
367	I2C_SET(dev,1,0);
368	I2C_SET(dev,1,1);
369	I2C_DEBUG(printf(">"));
370	return (0);
371}
372
373static int
374iicbb_write(device_t dev, char * buf, int len, int *sent, int timeout)
375{
376	int bytes, error = 0;
377
378	bytes = 0;
379	while (len) {
380		/* send byte */
381		iicbb_sendbyte(dev,(u_char)*buf++, timeout);
382
383		/* check for ack */
384		if (iicbb_ack(dev, timeout)) {
385			error = IIC_ENOACK;
386			goto error;
387		}
388		bytes ++;
389		len --;
390	}
391
392error:
393	*sent = bytes;
394	return (error);
395}
396
397static int
398iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
399{
400	int bytes;
401
402	bytes = 0;
403	while (len) {
404		/* XXX should insert delay here */
405		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
406
407		bytes ++;
408		len --;
409	}
410
411	*read = bytes;
412	return (0);
413}
414
415/*
416 * XXX This is lame.  We need to have a base iicbb_bridge class that all these
417 * XXX derive from.
418 */
419DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0);
420DRIVER_MODULE(iicbb, ixpiic, iicbb_driver, iicbb_devclass, 0, 0);
421DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
422DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
423DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, 0, 0);
424
425MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
426MODULE_VERSION(iicbb, IICBB_MODVER);
427