iicbb.c revision 228728 
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 228728 2011-12-20 02:49:01Z adrian $");
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	int udelay;		/* signal toggle delay in usec */
65};
66
67static int iicbb_attach(device_t);
68static void iicbb_child_detached(device_t, device_t);
69static int iicbb_detach(device_t);
70static int iicbb_print_child(device_t, device_t);
71static int iicbb_probe(device_t);
72
73static int iicbb_callback(device_t, int, caddr_t);
74static int iicbb_start(device_t, u_char, int);
75static int iicbb_stop(device_t);
76static int iicbb_write(device_t, const char *, int, int *, int);
77static int iicbb_read(device_t, char *, int, int *, int, int);
78static int iicbb_reset(device_t, u_char, u_char, u_char *);
79
80static device_method_t iicbb_methods[] = {
81	/* device interface */
82	DEVMETHOD(device_probe,		iicbb_probe),
83	DEVMETHOD(device_attach,	iicbb_attach),
84	DEVMETHOD(device_detach,	iicbb_detach),
85
86	/* bus interface */
87	DEVMETHOD(bus_child_detached,	iicbb_child_detached),
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	DEVMETHOD(iicbus_transfer,	iicbus_transfer_gen),
99
100	{ 0, 0 }
101};
102
103driver_t iicbb_driver = {
104	"iicbb",
105	iicbb_methods,
106	sizeof(struct iicbb_softc),
107};
108
109devclass_t iicbb_devclass;
110
111static int
112iicbb_probe(device_t dev)
113{
114	device_set_desc(dev, "I2C bit-banging driver");
115
116	return (0);
117}
118
119static int
120iicbb_attach(device_t dev)
121{
122	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
123
124	sc->iicbus = device_add_child(dev, "iicbus", -1);
125	if (!sc->iicbus)
126		return (ENXIO);
127	sc->udelay = 10;		/* 10 uS default */
128	bus_generic_attach(dev);
129
130	return (0);
131}
132
133static int
134iicbb_detach(device_t dev)
135{
136	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
137	device_t child;
138
139	/*
140	 * We need to save child because the detach indirectly causes
141	 * sc->iicbus to be zeroed.  Since we added the device
142	 * unconditionally in iicbb_attach, we need to make sure we
143	 * delete it here.  See iicbb_child_detached.  We need that
144	 * callback in case newbus detached our children w/o detaching
145	 * us (say iicbus is a module and unloaded w/o iicbb being
146	 * unloaded).
147	 */
148	child = sc->iicbus;
149	bus_generic_detach(dev);
150	if (child)
151		device_delete_child(dev, child);
152
153	return (0);
154}
155
156static void
157iicbb_child_detached( device_t dev, device_t child )
158{
159	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
160
161	if (child == sc->iicbus)
162		sc->iicbus = NULL;
163}
164
165static int
166iicbb_print_child(device_t bus, device_t dev)
167{
168	int error;
169	int retval = 0;
170	u_char oldaddr;
171
172	retval += bus_print_child_header(bus, dev);
173	/* retrieve the interface I2C address */
174	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
175	if (error == IIC_ENOADDR) {
176		retval += printf(" on %s master-only\n",
177				 device_get_nameunit(bus));
178	} else {
179		/* restore the address */
180		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
181
182		retval += printf(" on %s addr 0x%x\n",
183				 device_get_nameunit(bus), oldaddr & 0xff);
184	}
185
186	return (retval);
187}
188
189#define I2C_SETSDA(sc,dev,val) do {			\
190	IICBB_SETSDA(device_get_parent(dev), val);	\
191	DELAY(sc->udelay);				\
192	} while (0)
193
194#define I2C_SETSCL(dev,val) do {			\
195	iicbb_setscl(dev, val, 100);			\
196	} while (0)
197
198#define I2C_SET(sc,dev,ctrl,data) do {			\
199	I2C_SETSCL(dev, ctrl);				\
200	I2C_SETSDA(sc, dev, data);			\
201	} while (0)
202
203#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
204
205#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
206
207static int i2c_debug = 0;
208#define I2C_DEBUG(x)	do {					\
209				if (i2c_debug) (x);		\
210			} while (0)
211
212#define I2C_LOG(format,args...)	do {				\
213					printf(format, args);	\
214				} while (0)
215
216static void
217iicbb_setscl(device_t dev, int val, int timeout)
218{
219	struct iicbb_softc *sc = device_get_softc(dev);
220	int k = 0;
221
222	IICBB_SETSCL(device_get_parent(dev), val);
223	DELAY(sc->udelay);
224
225	while (val && !I2C_GETSCL(dev) && k++ < timeout) {
226		IICBB_SETSCL(device_get_parent(dev), val);
227		DELAY(sc->udelay);
228	}
229
230	return;
231}
232
233static void
234iicbb_one(device_t dev, int timeout)
235{
236	struct iicbb_softc *sc = device_get_softc(dev);
237
238	I2C_SET(sc,dev,0,1);
239	I2C_SET(sc,dev,1,1);
240	I2C_SET(sc,dev,0,1);
241	return;
242}
243
244static void
245iicbb_zero(device_t dev, int timeout)
246{
247	struct iicbb_softc *sc = device_get_softc(dev);
248
249	I2C_SET(sc,dev,0,0);
250	I2C_SET(sc,dev,1,0);
251	I2C_SET(sc,dev,0,0);
252	return;
253}
254
255/*
256 * Waiting for ACKNOWLEDGE.
257 *
258 * When a chip is being addressed or has received data it will issue an
259 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
260 * (set it to high level) and then release the CLOCK line.
261 * Now it must wait for the SLAVE to pull the DATA line low.
262 * Actually on the bus this looks like a START condition so nothing happens
263 * because of the fact that the IC's that have not been addressed are doing
264 * nothing.
265 *
266 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
267 * line low and then the SLAVE will release the SDA (data) line.
268 */
269static int
270iicbb_ack(device_t dev, int timeout)
271{
272	struct iicbb_softc *sc = device_get_softc(dev);
273	int noack;
274	int k = 0;
275
276	I2C_SET(sc,dev,0,1);
277	I2C_SET(sc,dev,1,1);
278	do {
279		noack = I2C_GETSDA(dev);
280		if (!noack)
281			break;
282		DELAY(1);
283		k++;
284	} while (k < timeout);
285
286	I2C_SET(sc,dev,0,1);
287	I2C_DEBUG(printf("%c ",noack?'-':'+'));
288
289	return (noack);
290}
291
292static void
293iicbb_sendbyte(device_t dev, u_char data, int timeout)
294{
295	int i;
296
297	for (i=7; i>=0; i--) {
298		if (data&(1<<i)) {
299			iicbb_one(dev, timeout);
300		} else {
301			iicbb_zero(dev, timeout);
302		}
303	}
304	I2C_DEBUG(printf("w%02x",(int)data));
305	return;
306}
307
308static u_char
309iicbb_readbyte(device_t dev, int last, int timeout)
310{
311	struct iicbb_softc *sc = device_get_softc(dev);
312	int i;
313	unsigned char data=0;
314
315	I2C_SET(sc,dev,0,1);
316	for (i=7; i>=0; i--)
317	{
318		I2C_SET(sc,dev,1,1);
319		if (I2C_GETSDA(dev))
320			data |= (1<<i);
321		I2C_SET(sc,dev,0,1);
322	}
323	if (last) {
324		iicbb_one(dev, timeout);
325	} else {
326		iicbb_zero(dev, timeout);
327	}
328	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
329	return data;
330}
331
332static int
333iicbb_callback(device_t dev, int index, caddr_t data)
334{
335	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
336}
337
338static int
339iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
340{
341	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
342}
343
344static int
345iicbb_start(device_t dev, u_char slave, int timeout)
346{
347	struct iicbb_softc *sc = device_get_softc(dev);
348	int error;
349
350	I2C_DEBUG(printf("<"));
351
352	I2C_SET(sc,dev,1,1);
353	I2C_SET(sc,dev,1,0);
354	I2C_SET(sc,dev,0,0);
355
356	/* send address */
357	iicbb_sendbyte(dev, slave, timeout);
358
359	/* check for ack */
360	if (iicbb_ack(dev, timeout)) {
361		error = IIC_ENOACK;
362		goto error;
363	}
364
365	return(0);
366
367error:
368	iicbb_stop(dev);
369	return (error);
370}
371
372static int
373iicbb_stop(device_t dev)
374{
375	struct iicbb_softc *sc = device_get_softc(dev);
376
377	I2C_SET(sc,dev,0,0);
378	I2C_SET(sc,dev,1,0);
379	I2C_SET(sc,dev,1,1);
380	I2C_DEBUG(printf(">"));
381	I2C_DEBUG(printf("\n"));
382	return (0);
383}
384
385static int
386iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
387{
388	int bytes, error = 0;
389
390	bytes = 0;
391	while (len) {
392		/* send byte */
393		iicbb_sendbyte(dev,(u_char)*buf++, timeout);
394
395		/* check for ack */
396		if (iicbb_ack(dev, timeout)) {
397			error = IIC_ENOACK;
398			goto error;
399		}
400		bytes ++;
401		len --;
402	}
403
404error:
405	*sent = bytes;
406	return (error);
407}
408
409static int
410iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
411{
412	int bytes;
413
414	bytes = 0;
415	while (len) {
416		/* XXX should insert delay here */
417		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
418
419		bytes ++;
420		len --;
421	}
422
423	*read = bytes;
424	return (0);
425}
426
427DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
428
429MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
430MODULE_VERSION(iicbb, IICBB_MODVER);
431