iicbb.c revision 232365 
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 232365 2012-03-01 20:58:20Z kan $");
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 *);
79static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
80
81static device_method_t iicbb_methods[] = {
82	/* device interface */
83	DEVMETHOD(device_probe,		iicbb_probe),
84	DEVMETHOD(device_attach,	iicbb_attach),
85	DEVMETHOD(device_detach,	iicbb_detach),
86
87	/* bus interface */
88	DEVMETHOD(bus_child_detached,	iicbb_child_detached),
89	DEVMETHOD(bus_print_child,	iicbb_print_child),
90
91	/* iicbus interface */
92	DEVMETHOD(iicbus_callback,	iicbb_callback),
93	DEVMETHOD(iicbus_start,		iicbb_start),
94	DEVMETHOD(iicbus_repeated_start, iicbb_start),
95	DEVMETHOD(iicbus_stop,		iicbb_stop),
96	DEVMETHOD(iicbus_write,		iicbb_write),
97	DEVMETHOD(iicbus_read,		iicbb_read),
98	DEVMETHOD(iicbus_reset,		iicbb_reset),
99	DEVMETHOD(iicbus_transfer,	iicbb_transfer),
100
101	{ 0, 0 }
102};
103
104driver_t iicbb_driver = {
105	"iicbb",
106	iicbb_methods,
107	sizeof(struct iicbb_softc),
108};
109
110devclass_t iicbb_devclass;
111
112static int
113iicbb_probe(device_t dev)
114{
115	device_set_desc(dev, "I2C bit-banging driver");
116
117	return (0);
118}
119
120static int
121iicbb_attach(device_t dev)
122{
123	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
124
125	sc->iicbus = device_add_child(dev, "iicbus", -1);
126	if (!sc->iicbus)
127		return (ENXIO);
128	sc->udelay = 10;		/* 10 uS default */
129	bus_generic_attach(dev);
130
131	return (0);
132}
133
134static int
135iicbb_detach(device_t dev)
136{
137	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
138	device_t child;
139
140	/*
141	 * We need to save child because the detach indirectly causes
142	 * sc->iicbus to be zeroed.  Since we added the device
143	 * unconditionally in iicbb_attach, we need to make sure we
144	 * delete it here.  See iicbb_child_detached.  We need that
145	 * callback in case newbus detached our children w/o detaching
146	 * us (say iicbus is a module and unloaded w/o iicbb being
147	 * unloaded).
148	 */
149	child = sc->iicbus;
150	bus_generic_detach(dev);
151	if (child)
152		device_delete_child(dev, child);
153
154	return (0);
155}
156
157static void
158iicbb_child_detached( device_t dev, device_t child )
159{
160	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
161
162	if (child == sc->iicbus)
163		sc->iicbus = NULL;
164}
165
166static int
167iicbb_print_child(device_t bus, device_t dev)
168{
169	int error;
170	int retval = 0;
171	u_char oldaddr;
172
173	retval += bus_print_child_header(bus, dev);
174	/* retrieve the interface I2C address */
175	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
176	if (error == IIC_ENOADDR) {
177		retval += printf(" on %s master-only\n",
178				 device_get_nameunit(bus));
179	} else {
180		/* restore the address */
181		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
182
183		retval += printf(" on %s addr 0x%x\n",
184				 device_get_nameunit(bus), oldaddr & 0xff);
185	}
186
187	return (retval);
188}
189
190#define I2C_SETSDA(sc,dev,val) do {			\
191	IICBB_SETSDA(device_get_parent(dev), val);	\
192	DELAY(sc->udelay);				\
193	} while (0)
194
195#define I2C_SETSCL(dev,val) do {			\
196	iicbb_setscl(dev, val, 100);			\
197	} while (0)
198
199#define I2C_SET(sc,dev,ctrl,data) do {			\
200	I2C_SETSCL(dev, ctrl);				\
201	I2C_SETSDA(sc, dev, data);			\
202	} while (0)
203
204#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
205
206#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
207
208static int i2c_debug = 0;
209#define I2C_DEBUG(x)	do {					\
210				if (i2c_debug) (x);		\
211			} while (0)
212
213#define I2C_LOG(format,args...)	do {				\
214					printf(format, args);	\
215				} while (0)
216
217static void
218iicbb_setscl(device_t dev, int val, int timeout)
219{
220	struct iicbb_softc *sc = device_get_softc(dev);
221	int k = 0;
222
223	IICBB_SETSCL(device_get_parent(dev), val);
224	DELAY(sc->udelay);
225
226	while (val && !I2C_GETSCL(dev) && k++ < timeout) {
227		IICBB_SETSCL(device_get_parent(dev), val);
228		DELAY(sc->udelay);
229	}
230
231	return;
232}
233
234static void
235iicbb_one(device_t dev, int timeout)
236{
237	struct iicbb_softc *sc = device_get_softc(dev);
238
239	I2C_SET(sc,dev,0,1);
240	I2C_SET(sc,dev,1,1);
241	I2C_SET(sc,dev,0,1);
242	return;
243}
244
245static void
246iicbb_zero(device_t dev, int timeout)
247{
248	struct iicbb_softc *sc = device_get_softc(dev);
249
250	I2C_SET(sc,dev,0,0);
251	I2C_SET(sc,dev,1,0);
252	I2C_SET(sc,dev,0,0);
253	return;
254}
255
256/*
257 * Waiting for ACKNOWLEDGE.
258 *
259 * When a chip is being addressed or has received data it will issue an
260 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
261 * (set it to high level) and then release the CLOCK line.
262 * Now it must wait for the SLAVE to pull the DATA line low.
263 * Actually on the bus this looks like a START condition so nothing happens
264 * because of the fact that the IC's that have not been addressed are doing
265 * nothing.
266 *
267 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
268 * line low and then the SLAVE will release the SDA (data) line.
269 */
270static int
271iicbb_ack(device_t dev, int timeout)
272{
273	struct iicbb_softc *sc = device_get_softc(dev);
274	int noack;
275	int k = 0;
276
277	I2C_SET(sc,dev,0,1);
278	I2C_SET(sc,dev,1,1);
279	do {
280		noack = I2C_GETSDA(dev);
281		if (!noack)
282			break;
283		DELAY(1);
284		k++;
285	} while (k < timeout);
286
287	I2C_SET(sc,dev,0,1);
288	I2C_DEBUG(printf("%c ",noack?'-':'+'));
289
290	return (noack);
291}
292
293static void
294iicbb_sendbyte(device_t dev, u_char data, int timeout)
295{
296	int i;
297
298	for (i=7; i>=0; i--) {
299		if (data&(1<<i)) {
300			iicbb_one(dev, timeout);
301		} else {
302			iicbb_zero(dev, timeout);
303		}
304	}
305	I2C_DEBUG(printf("w%02x",(int)data));
306	return;
307}
308
309static u_char
310iicbb_readbyte(device_t dev, int last, int timeout)
311{
312	struct iicbb_softc *sc = device_get_softc(dev);
313	int i;
314	unsigned char data=0;
315
316	I2C_SET(sc,dev,0,1);
317	for (i=7; i>=0; i--)
318	{
319		I2C_SET(sc,dev,1,1);
320		if (I2C_GETSDA(dev))
321			data |= (1<<i);
322		I2C_SET(sc,dev,0,1);
323	}
324	if (last) {
325		iicbb_one(dev, timeout);
326	} else {
327		iicbb_zero(dev, timeout);
328	}
329	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
330	return data;
331}
332
333static int
334iicbb_callback(device_t dev, int index, caddr_t data)
335{
336	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
337}
338
339static int
340iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
341{
342	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
343}
344
345static int
346iicbb_start(device_t dev, u_char slave, int timeout)
347{
348	struct iicbb_softc *sc = device_get_softc(dev);
349	int error;
350
351	I2C_DEBUG(printf("<"));
352
353	I2C_SET(sc,dev,1,1);
354	I2C_SET(sc,dev,1,0);
355	I2C_SET(sc,dev,0,0);
356
357	/* send address */
358	iicbb_sendbyte(dev, slave, timeout);
359
360	/* check for ack */
361	if (iicbb_ack(dev, timeout)) {
362		error = IIC_ENOACK;
363		goto error;
364	}
365
366	return(0);
367
368error:
369	iicbb_stop(dev);
370	return (error);
371}
372
373static int
374iicbb_stop(device_t dev)
375{
376	struct iicbb_softc *sc = device_get_softc(dev);
377
378	I2C_SET(sc,dev,0,0);
379	I2C_SET(sc,dev,1,0);
380	I2C_SET(sc,dev,1,1);
381	I2C_DEBUG(printf(">"));
382	I2C_DEBUG(printf("\n"));
383	return (0);
384}
385
386static int
387iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
388{
389	int bytes, error = 0;
390
391	bytes = 0;
392	while (len) {
393		/* send byte */
394		iicbb_sendbyte(dev,(u_char)*buf++, timeout);
395
396		/* check for ack */
397		if (iicbb_ack(dev, timeout)) {
398			error = IIC_ENOACK;
399			goto error;
400		}
401		bytes ++;
402		len --;
403	}
404
405error:
406	*sent = bytes;
407	return (error);
408}
409
410static int
411iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
412{
413	int bytes;
414
415	bytes = 0;
416	while (len) {
417		/* XXX should insert delay here */
418		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
419
420		bytes ++;
421		len --;
422	}
423
424	*read = bytes;
425	return (0);
426}
427
428static int
429iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
430{
431	int error;
432
433	error = IICBB_PRE_XFER(device_get_parent(dev));
434	if (error)
435		return (error);
436
437	error = iicbus_transfer_gen(dev, msgs, nmsgs);
438
439	IICBB_POST_XFER(device_get_parent(dev));
440	return (error);
441}
442
443DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
444
445MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
446MODULE_VERSION(iicbb, IICBB_MODVER);
447