xref: /dragonfly/sys/bus/iicbus/iicbb.c (revision 1ab20d67) 
1 /*-
2  * Copyright (c) 1998 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  * $FreeBSD: src/sys/dev/iicbus/iicbb.c,v 1.6.2.2 2002/04/19 05:52:12 nsouch Exp $
27  * $DragonFly: src/sys/bus/iicbus/iicbb.c,v 1.3 2003/08/07 21:16:45 dillon Exp $
28  *
29  */
30 
31 /*
32  * Generic I2C bit-banging code
33  *
34  * Example:
35  *
36  *	iicbus
37  *	 /  \
38  *    iicbb pcf
39  *     |  \
40  *   bti2c lpbb
41  *
42  * From Linux I2C generic interface
43  * (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
44  *
45  * TODO: port Peter's generic bit-banging code <dufault@hda.com>
46  */
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/conf.h>
54 #include <sys/buf.h>
55 #include <sys/uio.h>
56 #include <sys/malloc.h>
57 
58 #include <machine/clock.h>
59 
60 #include "iiconf.h"
61 #include "iicbus.h"
62 
63 #include <bus/smbus/smbconf.h>
64 
65 #include "iicbus_if.h"
66 #include "iicbb_if.h"
67 
68 struct iicbb_softc {
69 	device_t iicbus;
70 };
71 
72 static int iicbb_probe(device_t);
73 static int iicbb_attach(device_t);
74 static int iicbb_detach(device_t);
75 static int iicbb_print_child(device_t, device_t);
76 
77 static int iicbb_callback(device_t, int, caddr_t);
78 static int iicbb_start(device_t, u_char, int);
79 static int iicbb_stop(device_t);
80 static int iicbb_write(device_t, char *, int, int *, int);
81 static int iicbb_read(device_t, char *, int, int *, int, int);
82 static int iicbb_reset(device_t, u_char, u_char, u_char *);
83 
84 static device_method_t iicbb_methods[] = {
85 	/* device interface */
86 	DEVMETHOD(device_probe,		iicbb_probe),
87 	DEVMETHOD(device_attach,	iicbb_attach),
88 	DEVMETHOD(device_detach,	iicbb_detach),
89 
90 	/* bus interface */
91 	DEVMETHOD(bus_print_child,	iicbb_print_child),
92 
93 	/* iicbus interface */
94 	DEVMETHOD(iicbus_callback,	iicbb_callback),
95 	DEVMETHOD(iicbus_start,		iicbb_start),
96 	DEVMETHOD(iicbus_repeated_start, iicbb_start),
97 	DEVMETHOD(iicbus_stop,		iicbb_stop),
98 	DEVMETHOD(iicbus_write,		iicbb_write),
99 	DEVMETHOD(iicbus_read,		iicbb_read),
100 	DEVMETHOD(iicbus_reset,		iicbb_reset),
101 
102 	{ 0, 0 }
103 };
104 
105 static driver_t iicbb_driver = {
106 	"iicbb",
107 	iicbb_methods,
108 	sizeof(struct iicbb_softc),
109 };
110 
111 static devclass_t iicbb_devclass;
112 
113 static int iicbb_probe(device_t dev)
114 {
115 	device_set_desc(dev, "I2C bit-banging driver");
116 
117 	return (0);
118 }
119 
120 static int iicbb_attach(device_t dev)
121 {
122 	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
123 
124 	bzero(sc, sizeof(struct iicbb_softc));
125 
126 	sc->iicbus = device_add_child(dev, "iicbus", -1);
127 
128 	if (!sc->iicbus)
129 		return (ENXIO);
130 
131 	bus_generic_attach(dev);
132 
133 	return (0);
134 }
135 
136 static int iicbb_detach(device_t dev)
137 {
138 	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
139 
140 	if (sc->iicbus) {
141 		bus_generic_detach(dev);
142 		device_delete_child(dev, sc->iicbus);
143 	}
144 
145 	return (0);
146 }
147 
148 static int
149 iicbb_print_child(device_t bus, device_t dev)
150 {
151 	int error;
152 	int retval = 0;
153 	u_char oldaddr;
154 
155 	retval += bus_print_child_header(bus, dev);
156 	/* retrieve the interface I2C address */
157 	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
158 	if (error == IIC_ENOADDR) {
159 		retval += printf(" on %s master-only\n",
160 				 device_get_nameunit(bus));
161 	} else {
162 		/* restore the address */
163 		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
164 
165 		retval += printf(" on %s addr 0x%x\n",
166 				 device_get_nameunit(bus), oldaddr & 0xff);
167 	}
168 
169 	return (retval);
170 }
171 
172 #define I2C_SET(dev,ctrl,data) \
173 	IICBB_SETLINES(device_get_parent(dev), ctrl, data)
174 
175 #define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
176 
177 static int i2c_debug = 0;
178 #define I2C_DEBUG(x) if (i2c_debug) (x)
179 
180 static void iicbb_one(device_t dev)
181 {
182 	I2C_SET(dev,0,1);
183 	I2C_SET(dev,1,1);
184 	I2C_SET(dev,0,1);
185 	return;
186 }
187 
188 static void iicbb_zero(device_t dev)
189 {
190 	I2C_SET(dev,0,0);
191 	I2C_SET(dev,1,0);
192 	I2C_SET(dev,0,0);
193 	return;
194 }
195 
196 /*
197  * Waiting for ACKNOWLEDGE.
198  *
199  * When a chip is being addressed or has received data it will issue an
200  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
201  * (set it to high level) and then release the CLOCK line.
202  * Now it must wait for the SLAVE to pull the DATA line low.
203  * Actually on the bus this looks like a START condition so nothing happens
204  * because of the fact that the IC's that have not been addressed are doing
205  * nothing.
206  *
207  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
208  * line low and then the SLAVE will release the SDA (data) line.
209  */
210 static int iicbb_ack(device_t dev, int timeout)
211 {
212 	int noack;
213 	int k = timeout/10;
214 
215 	I2C_SET(dev,0,1);
216 	I2C_SET(dev,1,1);
217 
218 	do {
219 		noack = I2C_GET(dev);
220 		if (!noack)
221 			break;
222 		DELAY(10);		/* XXX wait 10us */
223 	} while (k--);
224 
225 	I2C_SET(dev,0,1);
226 	I2C_DEBUG(printf("%c ",noack?'-':'+'));
227 
228 	return (noack);
229 }
230 
231 static void iicbb_sendbyte(device_t dev, u_char data)
232 {
233 	int i;
234 
235 	I2C_SET(dev,0,0);
236 	for (i=7; i>=0; i--)
237 		(data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
238 	I2C_DEBUG(printf("w%02x",(int)data));
239 	return;
240 }
241 
242 static u_char iicbb_readbyte(device_t dev, int last)
243 {
244 	int i;
245 	unsigned char data=0;
246 
247 	I2C_SET(dev,0,1);
248 	for (i=7; i>=0; i--)
249 	{
250 		I2C_SET(dev,1,1);
251 		if (I2C_GET(dev))
252 			data |= (1<<i);
253 		I2C_SET(dev,0,1);
254 	}
255 	last ? iicbb_one(dev) : iicbb_zero(dev);
256 	I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
257 	return data;
258 }
259 
260 static int iicbb_callback(device_t dev, int index, caddr_t data)
261 {
262 	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
263 }
264 
265 static int iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
266 {
267 	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
268 }
269 
270 static int iicbb_start(device_t dev, u_char slave, int timeout)
271 {
272 	int error;
273 
274 	I2C_DEBUG(printf("<"));
275 
276 	I2C_SET(dev,0,1);
277 	I2C_SET(dev,1,1);
278 	I2C_SET(dev,1,0);
279 	I2C_SET(dev,0,0);
280 
281 	/* send address */
282 	iicbb_sendbyte(dev, slave);
283 
284 	/* check for ack */
285 	if (iicbb_ack(dev, timeout)) {
286 		error = IIC_ENOACK;
287 		goto error;
288 	}
289 
290 	return(0);
291 
292 error:
293 	iicbb_stop(dev);
294 	return (error);
295 }
296 
297 static int iicbb_stop(device_t dev)
298 {
299 	I2C_SET(dev,0,0);
300 	I2C_SET(dev,1,0);
301 	I2C_SET(dev,1,1);
302 	I2C_DEBUG(printf(">"));
303 	return (0);
304 }
305 
306 static int iicbb_write(device_t dev, char * buf, int len, int *sent,
307 			int timeout)
308 {
309 	int bytes, error = 0;
310 
311 	bytes = 0;
312 	while (len) {
313 		/* send byte */
314 		iicbb_sendbyte(dev,(u_char)*buf++);
315 
316 		/* check for ack */
317 		if (iicbb_ack(dev, timeout)) {
318 			error = IIC_ENOACK;
319 			goto error;
320 		}
321 		bytes ++;
322 		len --;
323 	}
324 
325 error:
326 	*sent = bytes;
327 	return (error);
328 }
329 
330 static int iicbb_read(device_t dev, char * buf, int len, int *read,
331 			int last, int delay)
332 {
333 	int bytes;
334 
335 	bytes = 0;
336 	while (len) {
337 		/* XXX should insert delay here */
338 		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
339 
340 		bytes ++;
341 		len --;
342 	}
343 
344 	*read = bytes;
345 	return (0);
346 }
347 
348 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
349 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
350 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
351