xref: /dragonfly/sys/bus/iicbus/iicbb.c (revision 85f8e2ea) 
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 1.5 2006/12/22 23:12:16 swildner 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
114 iicbb_probe(device_t dev)
115 {
116 	device_set_desc(dev, "I2C bit-banging driver");
117 
118 	return (0);
119 }
120 
121 static int
122 iicbb_attach(device_t dev)
123 {
124 	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
125 
126 	bzero(sc, sizeof(struct iicbb_softc));
127 
128 	sc->iicbus = device_add_child(dev, "iicbus", -1);
129 
130 	if (!sc->iicbus)
131 		return (ENXIO);
132 
133 	bus_generic_attach(dev);
134 
135 	return (0);
136 }
137 
138 static int
139 iicbb_detach(device_t dev)
140 {
141 	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
142 
143 	if (sc->iicbus) {
144 		bus_generic_detach(dev);
145 		device_delete_child(dev, sc->iicbus);
146 	}
147 
148 	return (0);
149 }
150 
151 static int
152 iicbb_print_child(device_t bus, device_t dev)
153 {
154 	int error;
155 	int retval = 0;
156 	u_char oldaddr;
157 
158 	retval += bus_print_child_header(bus, dev);
159 	/* retrieve the interface I2C address */
160 	error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
161 	if (error == IIC_ENOADDR) {
162 		retval += kprintf(" on %s master-only\n",
163 				 device_get_nameunit(bus));
164 	} else {
165 		/* restore the address */
166 		IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
167 
168 		retval += kprintf(" on %s addr 0x%x\n",
169 				 device_get_nameunit(bus), oldaddr & 0xff);
170 	}
171 
172 	return (retval);
173 }
174 
175 #define I2C_SET(dev,ctrl,data) \
176 	IICBB_SETLINES(device_get_parent(dev), ctrl, data)
177 
178 #define I2C_GET(dev) (IICBB_GETDATALINE(device_get_parent(dev)))
179 
180 static int i2c_debug = 0;
181 #define I2C_DEBUG(x) if (i2c_debug) (x)
182 
183 static void
184 iicbb_one(device_t dev)
185 {
186 	I2C_SET(dev,0,1);
187 	I2C_SET(dev,1,1);
188 	I2C_SET(dev,0,1);
189 	return;
190 }
191 
192 static void
193 iicbb_zero(device_t dev)
194 {
195 	I2C_SET(dev,0,0);
196 	I2C_SET(dev,1,0);
197 	I2C_SET(dev,0,0);
198 	return;
199 }
200 
201 /*
202  * Waiting for ACKNOWLEDGE.
203  *
204  * When a chip is being addressed or has received data it will issue an
205  * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
206  * (set it to high level) and then release the CLOCK line.
207  * Now it must wait for the SLAVE to pull the DATA line low.
208  * Actually on the bus this looks like a START condition so nothing happens
209  * because of the fact that the IC's that have not been addressed are doing
210  * nothing.
211  *
212  * When the SLAVE has pulled this line low the MASTER will take the CLOCK
213  * line low and then the SLAVE will release the SDA (data) line.
214  */
215 static int
216 iicbb_ack(device_t dev, int timeout)
217 {
218 	int noack;
219 	int k = timeout/10;
220 
221 	I2C_SET(dev,0,1);
222 	I2C_SET(dev,1,1);
223 
224 	do {
225 		noack = I2C_GET(dev);
226 		if (!noack)
227 			break;
228 		DELAY(10);		/* XXX wait 10us */
229 	} while (k--);
230 
231 	I2C_SET(dev,0,1);
232 	I2C_DEBUG(kprintf("%c ",noack?'-':'+'));
233 
234 	return (noack);
235 }
236 
237 static void
238 iicbb_sendbyte(device_t dev, u_char data)
239 {
240 	int i;
241 
242 	I2C_SET(dev,0,0);
243 	for (i=7; i>=0; i--)
244 		(data&(1<<i)) ? iicbb_one(dev) : iicbb_zero(dev);
245 	I2C_DEBUG(kprintf("w%02x",(int)data));
246 	return;
247 }
248 
249 static u_char
250 iicbb_readbyte(device_t dev, int last)
251 {
252 	int i;
253 	unsigned char data=0;
254 
255 	I2C_SET(dev,0,1);
256 	for (i=7; i>=0; i--)
257 	{
258 		I2C_SET(dev,1,1);
259 		if (I2C_GET(dev))
260 			data |= (1<<i);
261 		I2C_SET(dev,0,1);
262 	}
263 	last ? iicbb_one(dev) : iicbb_zero(dev);
264 	I2C_DEBUG(kprintf("r%02x%c ",(int)data,last?'-':'+'));
265 	return data;
266 }
267 
268 static int
269 iicbb_callback(device_t dev, int index, caddr_t data)
270 {
271 	return (IICBB_CALLBACK(device_get_parent(dev), index, data));
272 }
273 
274 static int
275 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
276 {
277 	return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
278 }
279 
280 static int
281 iicbb_start(device_t dev, u_char slave, int timeout)
282 {
283 	int error;
284 
285 	I2C_DEBUG(kprintf("<"));
286 
287 	I2C_SET(dev,0,1);
288 	I2C_SET(dev,1,1);
289 	I2C_SET(dev,1,0);
290 	I2C_SET(dev,0,0);
291 
292 	/* send address */
293 	iicbb_sendbyte(dev, slave);
294 
295 	/* check for ack */
296 	if (iicbb_ack(dev, timeout)) {
297 		error = IIC_ENOACK;
298 		goto error;
299 	}
300 
301 	return(0);
302 
303 error:
304 	iicbb_stop(dev);
305 	return (error);
306 }
307 
308 static int
309 iicbb_stop(device_t dev)
310 {
311 	I2C_SET(dev,0,0);
312 	I2C_SET(dev,1,0);
313 	I2C_SET(dev,1,1);
314 	I2C_DEBUG(kprintf(">"));
315 	return (0);
316 }
317 
318 static int
319 iicbb_write(device_t dev, char * buf, int len, int *sent, int timeout)
320 {
321 	int bytes, error = 0;
322 
323 	bytes = 0;
324 	while (len) {
325 		/* send byte */
326 		iicbb_sendbyte(dev,(u_char)*buf++);
327 
328 		/* check for ack */
329 		if (iicbb_ack(dev, timeout)) {
330 			error = IIC_ENOACK;
331 			goto error;
332 		}
333 		bytes ++;
334 		len --;
335 	}
336 
337 error:
338 	*sent = bytes;
339 	return (error);
340 }
341 
342 static int
343 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
344 {
345 	int bytes;
346 
347 	bytes = 0;
348 	while (len) {
349 		/* XXX should insert delay here */
350 		*buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0);
351 
352 		bytes ++;
353 		len --;
354 	}
355 
356 	*read = bytes;
357 	return (0);
358 }
359 
360 DRIVER_MODULE(iicbb, bti2c, iicbb_driver, iicbb_devclass, 0, 0);
361 DRIVER_MODULE(iicbb, lpbb, iicbb_driver, iicbb_devclass, 0, 0);
362 DRIVER_MODULE(iicbb, viapm, iicbb_driver, iicbb_devclass, 0, 0);
363