iicbb.c revision 261844 
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 261844 2014-02-13 18:22:49Z loos $");
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 "opt_platform.h"
47
48#include <sys/param.h>
49#include <sys/kernel.h>
50#include <sys/systm.h>
51#include <sys/module.h>
52#include <sys/bus.h>
53#include <sys/uio.h>
54
55#ifdef FDT
56#include <dev/ofw/ofw_bus.h>
57#include <dev/ofw/ofw_bus_subr.h>
58#include <dev/fdt/fdt_common.h>
59#endif
60
61#include <dev/iicbus/iiconf.h>
62#include <dev/iicbus/iicbus.h>
63
64#include <dev/smbus/smbconf.h>
65
66#include "iicbus_if.h"
67#include "iicbb_if.h"
68
69struct iicbb_softc {
70	device_t iicbus;
71	int udelay;		/* signal toggle delay in usec */
72};
73
74static int iicbb_attach(device_t);
75static void iicbb_child_detached(device_t, device_t);
76static int iicbb_detach(device_t);
77static int iicbb_print_child(device_t, device_t);
78static int iicbb_probe(device_t);
79
80static int iicbb_callback(device_t, int, caddr_t);
81static int iicbb_start(device_t, u_char, int);
82static int iicbb_stop(device_t);
83static int iicbb_write(device_t, const char *, int, int *, int);
84static int iicbb_read(device_t, char *, int, int *, int, int);
85static int iicbb_reset(device_t, u_char, u_char, u_char *);
86static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
87#ifdef FDT
88static phandle_t iicbb_get_node(device_t, device_t);
89#endif
90
91static device_method_t iicbb_methods[] = {
92	/* device interface */
93	DEVMETHOD(device_probe,		iicbb_probe),
94	DEVMETHOD(device_attach,	iicbb_attach),
95	DEVMETHOD(device_detach,	iicbb_detach),
96
97	/* bus interface */
98	DEVMETHOD(bus_child_detached,	iicbb_child_detached),
99	DEVMETHOD(bus_print_child,	iicbb_print_child),
100
101	/* iicbus interface */
102	DEVMETHOD(iicbus_callback,	iicbb_callback),
103	DEVMETHOD(iicbus_start,		iicbb_start),
104	DEVMETHOD(iicbus_repeated_start, iicbb_start),
105	DEVMETHOD(iicbus_stop,		iicbb_stop),
106	DEVMETHOD(iicbus_write,		iicbb_write),
107	DEVMETHOD(iicbus_read,		iicbb_read),
108	DEVMETHOD(iicbus_reset,		iicbb_reset),
109	DEVMETHOD(iicbus_transfer,	iicbb_transfer),
110
111#ifdef FDT
112	/* ofw_bus interface */
113	DEVMETHOD(ofw_bus_get_node,	iicbb_get_node),
114#endif
115
116	{ 0, 0 }
117};
118
119driver_t iicbb_driver = {
120	"iicbb",
121	iicbb_methods,
122	sizeof(struct iicbb_softc),
123};
124
125devclass_t iicbb_devclass;
126
127static int
128iicbb_probe(device_t dev)
129{
130	device_set_desc(dev, "I2C bit-banging driver");
131
132	return (0);
133}
134
135static int
136iicbb_attach(device_t dev)
137{
138	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
139
140	sc->iicbus = device_add_child(dev, "iicbus", -1);
141	if (!sc->iicbus)
142		return (ENXIO);
143	sc->udelay = 10;		/* 10 uS default */
144	bus_generic_attach(dev);
145
146	return (0);
147}
148
149static int
150iicbb_detach(device_t dev)
151{
152	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
153	device_t child;
154
155	/*
156	 * We need to save child because the detach indirectly causes
157	 * sc->iicbus to be zeroed.  Since we added the device
158	 * unconditionally in iicbb_attach, we need to make sure we
159	 * delete it here.  See iicbb_child_detached.  We need that
160	 * callback in case newbus detached our children w/o detaching
161	 * us (say iicbus is a module and unloaded w/o iicbb being
162	 * unloaded).
163	 */
164	child = sc->iicbus;
165	bus_generic_detach(dev);
166	if (child)
167		device_delete_child(dev, child);
168
169	return (0);
170}
171
172#ifdef FDT
173static phandle_t
174iicbb_get_node(device_t bus, device_t dev)
175{
176
177	/* We only have one child, the I2C bus, which needs our own node. */
178	return (ofw_bus_get_node(bus));
179}
180#endif
181
182static void
183iicbb_child_detached( device_t dev, device_t child )
184{
185	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
186
187	if (child == sc->iicbus)
188		sc->iicbus = NULL;
189}
190
191static int
192iicbb_print_child(device_t bus, device_t dev)
193{
194	int error;
195	int retval = 0;
196	u_char oldaddr;
197
198	retval += bus_print_child_header(bus, dev);
199	/* retrieve the interface I2C address */
200	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
201	if (error == IIC_ENOADDR) {
202		retval += printf(" on %s master-only\n",
203				 device_get_nameunit(bus));
204	} else {
205		/* restore the address */
206		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
207
208		retval += printf(" on %s addr 0x%x\n",
209				 device_get_nameunit(bus), oldaddr & 0xff);
210	}
211
212	return (retval);
213}
214
215#define I2C_SETSDA(sc,dev,val) do {			\
216	IICBB_SETSDA(device_get_parent(dev), val);	\
217	DELAY(sc->udelay);				\
218	} while (0)
219
220#define I2C_SETSCL(dev,val) do {			\
221	iicbb_setscl(dev, val, 100);			\
222	} while (0)
223
224#define I2C_SET(sc,dev,ctrl,data) do {			\
225	I2C_SETSCL(dev, ctrl);				\
226	I2C_SETSDA(sc, dev, data);			\
227	} while (0)
228
229#define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
230
231#define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
232
233static int i2c_debug = 0;
234#define I2C_DEBUG(x)	do {					\
235				if (i2c_debug) (x);		\
236			} while (0)
237
238#define I2C_LOG(format,args...)	do {				\
239					printf(format, args);	\
240				} while (0)
241
242static void
243iicbb_setscl(device_t dev, int val, int timeout)
244{
245	struct iicbb_softc *sc = device_get_softc(dev);
246	int k = 0;
247
248	IICBB_SETSCL(device_get_parent(dev), val);
249	DELAY(sc->udelay);
250
251	while (val && !I2C_GETSCL(dev) && k++ < timeout) {
252		IICBB_SETSCL(device_get_parent(dev), val);
253		DELAY(sc->udelay);
254	}
255
256	return;
257}
258
259static void
260iicbb_one(device_t dev, int timeout)
261{
262	struct iicbb_softc *sc = device_get_softc(dev);
263
264	I2C_SET(sc,dev,0,1);
265	I2C_SET(sc,dev,1,1);
266	I2C_SET(sc,dev,0,1);
267	return;
268}
269
270static void
271iicbb_zero(device_t dev, int timeout)
272{
273	struct iicbb_softc *sc = device_get_softc(dev);
274
275	I2C_SET(sc,dev,0,0);
276	I2C_SET(sc,dev,1,0);
277	I2C_SET(sc,dev,0,0);
278	return;
279}
280
281/*
282 * Waiting for ACKNOWLEDGE.
283 *
284 * When a chip is being addressed or has received data it will issue an
285 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
286 * (set it to high level) and then release the CLOCK line.
287 * Now it must wait for the SLAVE to pull the DATA line low.
288 * Actually on the bus this looks like a START condition so nothing happens
289 * because of the fact that the IC's that have not been addressed are doing
290 * nothing.
291 *
292 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
293 * line low and then the SLAVE will release the SDA (data) line.
294 */
295static int
296iicbb_ack(device_t dev, int timeout)
297{
298	struct iicbb_softc *sc = device_get_softc(dev);
299	int noack;
300	int k = 0;
301
302	I2C_SET(sc,dev,0,1);
303	I2C_SET(sc,dev,1,1);
304	do {
305		noack = I2C_GETSDA(dev);
306		if (!noack)
307			break;
308		DELAY(1);
309		k++;
310	} while (k < timeout);
311
312	I2C_SET(sc,dev,0,1);
313	I2C_DEBUG(printf("%c ",noack?'-':'+'));
314
315	return (noack);
316}
317
318static void
319iicbb_sendbyte(device_t dev, u_char data, int timeout)
320{
321	int i;
322
323	for (i=7; i>=0; i--) {
324		if (data&(1<<i)) {
325			iicbb_one(dev, timeout);
326		} else {
327			iicbb_zero(dev, timeout);
328		}
329	}
330	I2C_DEBUG(printf("w%02x",(int)data));
331	return;
332}
333
334static u_char
335iicbb_readbyte(device_t dev, int last, int timeout)
336{
337	struct iicbb_softc *sc = device_get_softc(dev);
338	int i;
339	unsigned char data=0;
340
341	I2C_SET(sc,dev,0,1);
342	for (i=7; i>=0; i--)
343	{
344		I2C_SET(sc,dev,1,1);
345		if (I2C_GETSDA(dev))
346			data |= (1<<i);
347		I2C_SET(sc,dev,0,1);
348	}
349	if (last) {
350		iicbb_one(dev, timeout);
351	} else {
352		iicbb_zero(dev, timeout);
353	}
354	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
355	return data;
356}
357
358static int
359iicbb_callback(device_t dev, int index, caddr_t data)
360{
361	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
362}
363
364static int
365iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
366{
367	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
368}
369
370static int
371iicbb_start(device_t dev, u_char slave, int timeout)
372{
373	struct iicbb_softc *sc = device_get_softc(dev);
374	int error;
375
376	I2C_DEBUG(printf("<"));
377
378	I2C_SET(sc,dev,1,1);
379	I2C_SET(sc,dev,1,0);
380	I2C_SET(sc,dev,0,0);
381
382	/* send address */
383	iicbb_sendbyte(dev, slave, timeout);
384
385	/* check for ack */
386	if (iicbb_ack(dev, timeout)) {
387		error = IIC_ENOACK;
388		goto error;
389	}
390
391	return(0);
392
393error:
394	iicbb_stop(dev);
395	return (error);
396}
397
398static int
399iicbb_stop(device_t dev)
400{
401	struct iicbb_softc *sc = device_get_softc(dev);
402
403	I2C_SET(sc,dev,0,0);
404	I2C_SET(sc,dev,1,0);
405	I2C_SET(sc,dev,1,1);
406	I2C_DEBUG(printf(">"));
407	I2C_DEBUG(printf("\n"));
408	return (0);
409}
410
411static int
412iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
413{
414	int bytes, error = 0;
415
416	bytes = 0;
417	while (len) {
418		/* send byte */
419		iicbb_sendbyte(dev,(u_char)*buf++, timeout);
420
421		/* check for ack */
422		if (iicbb_ack(dev, timeout)) {
423			error = IIC_ENOACK;
424			goto error;
425		}
426		bytes ++;
427		len --;
428	}
429
430error:
431	*sent = bytes;
432	return (error);
433}
434
435static int
436iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
437{
438	int bytes;
439
440	bytes = 0;
441	while (len) {
442		/* XXX should insert delay here */
443		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
444
445		bytes ++;
446		len --;
447	}
448
449	*read = bytes;
450	return (0);
451}
452
453static int
454iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
455{
456	int error;
457
458	error = IICBB_PRE_XFER(device_get_parent(dev));
459	if (error)
460		return (error);
461
462	error = iicbus_transfer_gen(dev, msgs, nmsgs);
463
464	IICBB_POST_XFER(device_get_parent(dev));
465	return (error);
466}
467
468DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
469
470MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
471MODULE_VERSION(iicbb, IICBB_MODVER);
472