iicbb.c revision 167855 
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 167855 2007-03-23 23:03:54Z 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	DEVMETHOD(iicbus_transfer,	iicbus_transfer_gen),
98
99	{ 0, 0 }
100};
101
102driver_t iicbb_driver = {
103	"iicbb",
104	iicbb_methods,
105	sizeof(struct iicbb_softc),
106};
107
108devclass_t iicbb_devclass;
109
110static int
111iicbb_probe(device_t dev)
112{
113	device_set_desc(dev, "I2C bit-banging driver");
114
115	return (0);
116}
117
118static int
119iicbb_attach(device_t dev)
120{
121	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
122
123	sc->iicbus = device_add_child(dev, "iicbus", -1);
124	if (!sc->iicbus)
125		return (ENXIO);
126	bus_generic_attach(dev);
127
128	return (0);
129}
130
131static int
132iicbb_detach(device_t dev)
133{
134	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
135	device_t child;
136
137	/*
138	 * We need to save child because the detach indirectly causes
139	 * sc->iicbus to be zeroed.  Since we added the device
140	 * unconditionally in iicbb_attach, we need to make sure we
141	 * delete it here.  See iicbb_child_detached.  We need that
142	 * callback in case newbus detached our children w/o detaching
143	 * us (say iicbus is a module and unloaded w/o iicbb being
144	 * unloaded).
145	 */
146	child = sc->iicbus;
147	bus_generic_detach(dev);
148	if (child)
149		device_delete_child(dev, child);
150
151	return (0);
152}
153
154static void
155iicbb_child_detached( device_t dev, device_t child )
156{
157	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
158
159	if (child == sc->iicbus)
160		sc->iicbus = NULL;
161}
162
163static int
164iicbb_print_child(device_t bus, device_t dev)
165{
166	int error;
167	int retval = 0;
168	u_char oldaddr;
169
170	retval += bus_print_child_header(bus, dev);
171	/* retrieve the interface I2C address */
172	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
173	if (error == IIC_ENOADDR) {
174		retval += printf(" on %s master-only\n",
175				 device_get_nameunit(bus));
176	} else {
177		/* restore the address */
178		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
179
180		retval += printf(" on %s addr 0x%x\n",
181				 device_get_nameunit(bus), oldaddr & 0xff);
182	}
183
184	return (retval);
185}
186
187#define IIC_DELAY	10
188
189#define I2C_SETSDA(dev,val) do {			\
190	IICBB_SETSDA(device_get_parent(dev), val);	\
191	DELAY(IIC_DELAY);				\
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(dev,ctrl,data) do {			\
199	I2C_SETSCL(dev, ctrl);				\
200	I2C_SETSDA(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	int k = 0;
220
221	IICBB_SETSCL(device_get_parent(dev), val);
222	DELAY(IIC_DELAY);
223
224	while (val && !I2C_GETSCL(dev) && k++ < timeout) {
225		IICBB_SETSCL(device_get_parent(dev), val);
226		DELAY(IIC_DELAY);
227	}
228
229	return;
230}
231
232static void
233iicbb_one(device_t dev, int timeout)
234{
235	I2C_SET(dev,0,1);
236	I2C_SET(dev,1,1);
237	I2C_SET(dev,0,1);
238	return;
239}
240
241static void
242iicbb_zero(device_t dev, int timeout)
243{
244	I2C_SET(dev,0,0);
245	I2C_SET(dev,1,0);
246	I2C_SET(dev,0,0);
247	return;
248}
249
250/*
251 * Waiting for ACKNOWLEDGE.
252 *
253 * When a chip is being addressed or has received data it will issue an
254 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
255 * (set it to high level) and then release the CLOCK line.
256 * Now it must wait for the SLAVE to pull the DATA line low.
257 * Actually on the bus this looks like a START condition so nothing happens
258 * because of the fact that the IC's that have not been addressed are doing
259 * nothing.
260 *
261 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
262 * line low and then the SLAVE will release the SDA (data) line.
263 */
264static int
265iicbb_ack(device_t dev, int timeout)
266{
267	int noack;
268	int k = 0;
269
270	I2C_SET(dev,0,1);
271	I2C_SET(dev,1,1);
272	do {
273		noack = I2C_GETSDA(dev);
274		if (!noack)
275			break;
276		DELAY(10);
277		k += 10;
278	} while (k < timeout);
279
280	I2C_SET(dev,0,1);
281	I2C_DEBUG(printf("%c ",noack?'-':'+'));
282
283	return (noack);
284}
285
286static void
287iicbb_sendbyte(device_t dev, u_char data, int timeout)
288{
289	int i;
290
291	for (i=7; i>=0; i--) {
292		if (data&(1<<i)) {
293			iicbb_one(dev, timeout);
294		} else {
295			iicbb_zero(dev, timeout);
296		}
297	}
298	I2C_DEBUG(printf("w%02x",(int)data));
299	return;
300}
301
302static u_char
303iicbb_readbyte(device_t dev, int last, int timeout)
304{
305	int i;
306	unsigned char data=0;
307
308	I2C_SET(dev,0,1);
309	for (i=7; i>=0; i--)
310	{
311		I2C_SET(dev,1,1);
312		if (I2C_GETSDA(dev))
313			data |= (1<<i);
314		I2C_SET(dev,0,1);
315	}
316	if (last) {
317		iicbb_one(dev, timeout);
318	} else {
319		iicbb_zero(dev, timeout);
320	}
321	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
322	return data;
323}
324
325static int
326iicbb_callback(device_t dev, int index, caddr_t data)
327{
328	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
329}
330
331static int
332iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
333{
334	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
335}
336
337static int
338iicbb_start(device_t dev, u_char slave, int timeout)
339{
340	int error;
341
342	I2C_DEBUG(printf("<"));
343
344	I2C_SET(dev,1,1);
345	I2C_SET(dev,1,0);
346	I2C_SET(dev,0,0);
347
348	/* send address */
349	iicbb_sendbyte(dev, slave, timeout);
350
351	/* check for ack */
352	if (iicbb_ack(dev, timeout)) {
353		error = IIC_ENOACK;
354		goto error;
355	}
356
357	return(0);
358
359error:
360	iicbb_stop(dev);
361	return (error);
362}
363
364static int
365iicbb_stop(device_t dev)
366{
367	I2C_SET(dev,0,0);
368	I2C_SET(dev,1,0);
369	I2C_SET(dev,1,1);
370	I2C_DEBUG(printf(">"));
371	return (0);
372}
373
374static int
375iicbb_write(device_t dev, char * buf, int len, int *sent, int timeout)
376{
377	int bytes, error = 0;
378
379	bytes = 0;
380	while (len) {
381		/* send byte */
382		iicbb_sendbyte(dev,(u_char)*buf++, timeout);
383
384		/* check for ack */
385		if (iicbb_ack(dev, timeout)) {
386			error = IIC_ENOACK;
387			goto error;
388		}
389		bytes ++;
390		len --;
391	}
392
393error:
394	*sent = bytes;
395	return (error);
396}
397
398static int
399iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
400{
401	int bytes;
402
403	bytes = 0;
404	while (len) {
405		/* XXX should insert delay here */
406		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
407
408		bytes ++;
409		len --;
410	}
411
412	*read = bytes;
413	return (0);
414}
415
416/*
417 * XXX This is lame.  We need to have a base iicbb_bridge class that all these
418 * XXX derive from.
419 */
420DRIVER_MODULE(iicbb, bktr, iicbb_driver, iicbb_devclass, 0, 0);
421DRIVER_MODULE(iicbb, ixpiic, iicbb_driver, iicbb_devclass, 0, 0);
422DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
423DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
424DRIVER_MODULE(iicbb, cxm_iic, iicbb_driver, iicbb_devclass, 0, 0);
425DRIVER_MODULE(iicbb, at91_bbiic, iicbb_driver, iicbb_devclass, 0, 0);
426
427MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
428MODULE_VERSION(iicbb, IICBB_MODVER);
429