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: stable/9/sys/dev/iicbus/iicbb.c 262745 2014-03-04 18:27:00Z dumbbell $");
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
62 struct iicbb_softc {
63 device_t iicbus;
64 };
65
66 static int iicbb_attach(device_t);
67 static void iicbb_child_detached(device_t, device_t);
68 static int iicbb_detach(device_t);
69 static int iicbb_print_child(device_t, device_t);
70 static int iicbb_probe(device_t);
71
72 static int iicbb_callback(device_t, int, caddr_t);
73 static int iicbb_start(device_t, u_char, int);
74 static int iicbb_stop(device_t);
75 static int iicbb_write(device_t, const char *, int, int *, int);
76 static int iicbb_read(device_t, char *, int, int *, int, int);
77 static int iicbb_reset(device_t, u_char, u_char, u_char *);
78 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
79
80 static device_method_t iicbb_methods[] = {
81 /* device interface */
82 DEVMETHOD(device_probe, iicbb_probe),
83 DEVMETHOD(device_attach, iicbb_attach),
84 DEVMETHOD(device_detach, iicbb_detach),
85
86 /* bus interface */
87 DEVMETHOD(bus_child_detached, iicbb_child_detached),
88 DEVMETHOD(bus_print_child, iicbb_print_child),
89
90 /* iicbus interface */
91 DEVMETHOD(iicbus_callback, iicbb_callback),
92 DEVMETHOD(iicbus_start, iicbb_start),
93 DEVMETHOD(iicbus_repeated_start, iicbb_start),
94 DEVMETHOD(iicbus_stop, iicbb_stop),
95 DEVMETHOD(iicbus_write, iicbb_write),
96 DEVMETHOD(iicbus_read, iicbb_read),
97 DEVMETHOD(iicbus_reset, iicbb_reset),
98 DEVMETHOD(iicbus_transfer, iicbb_transfer),
99
100 { 0, 0 }
101 };
102
103 driver_t iicbb_driver = {
104 "iicbb",
105 iicbb_methods,
106 sizeof(struct iicbb_softc),
107 };
108
109 devclass_t iicbb_devclass;
110
111 static int
iicbb_probe(device_t dev)112 iicbb_probe(device_t dev)
113 {
114 device_set_desc(dev, "I2C bit-banging driver");
115
116 return (0);
117 }
118
119 static int
iicbb_attach(device_t dev)120 iicbb_attach(device_t dev)
121 {
122 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
123
124 sc->iicbus = device_add_child(dev, "iicbus", -1);
125 if (!sc->iicbus)
126 return (ENXIO);
127 bus_generic_attach(dev);
128
129 return (0);
130 }
131
132 static int
iicbb_detach(device_t dev)133 iicbb_detach(device_t dev)
134 {
135 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
136 device_t child;
137
138 /*
139 * We need to save child because the detach indirectly causes
140 * sc->iicbus to be zeroed. Since we added the device
141 * unconditionally in iicbb_attach, we need to make sure we
142 * delete it here. See iicbb_child_detached. We need that
143 * callback in case newbus detached our children w/o detaching
144 * us (say iicbus is a module and unloaded w/o iicbb being
145 * unloaded).
146 */
147 child = sc->iicbus;
148 bus_generic_detach(dev);
149 if (child)
150 device_delete_child(dev, child);
151
152 return (0);
153 }
154
155 static void
iicbb_child_detached(device_t dev,device_t child)156 iicbb_child_detached( device_t dev, device_t child )
157 {
158 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
159
160 if (child == sc->iicbus)
161 sc->iicbus = NULL;
162 }
163
164 static int
iicbb_print_child(device_t bus,device_t dev)165 iicbb_print_child(device_t bus, device_t dev)
166 {
167 int error;
168 int retval = 0;
169 u_char oldaddr;
170
171 retval += bus_print_child_header(bus, dev);
172 /* retrieve the interface I2C address */
173 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
174 if (error == IIC_ENOADDR) {
175 retval += printf(" on %s master-only\n",
176 device_get_nameunit(bus));
177 } else {
178 /* restore the address */
179 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
180
181 retval += printf(" on %s addr 0x%x\n",
182 device_get_nameunit(bus), oldaddr & 0xff);
183 }
184
185 return (retval);
186 }
187
188 #define IIC_DELAY 10
189
190 #define I2C_SETSDA(dev,val) do { \
191 IICBB_SETSDA(device_get_parent(dev), val); \
192 DELAY(IIC_DELAY); \
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(dev,ctrl,data) do { \
200 I2C_SETSCL(dev, ctrl); \
201 I2C_SETSDA(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
208 static 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
217 static void
iicbb_setscl(device_t dev,int val,int timeout)218 iicbb_setscl(device_t dev, int val, int timeout)
219 {
220 int k = 0;
221
222 IICBB_SETSCL(device_get_parent(dev), val);
223 DELAY(IIC_DELAY);
224
225 while (val && !I2C_GETSCL(dev) && k++ < timeout) {
226 IICBB_SETSCL(device_get_parent(dev), val);
227 DELAY(IIC_DELAY);
228 }
229
230 return;
231 }
232
233 static void
iicbb_one(device_t dev,int timeout)234 iicbb_one(device_t dev, int timeout)
235 {
236 I2C_SET(dev,0,1);
237 I2C_SET(dev,1,1);
238 I2C_SET(dev,0,1);
239 return;
240 }
241
242 static void
iicbb_zero(device_t dev,int timeout)243 iicbb_zero(device_t dev, int timeout)
244 {
245 I2C_SET(dev,0,0);
246 I2C_SET(dev,1,0);
247 I2C_SET(dev,0,0);
248 return;
249 }
250
251 /*
252 * Waiting for ACKNOWLEDGE.
253 *
254 * When a chip is being addressed or has received data it will issue an
255 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
256 * (set it to high level) and then release the CLOCK line.
257 * Now it must wait for the SLAVE to pull the DATA line low.
258 * Actually on the bus this looks like a START condition so nothing happens
259 * because of the fact that the IC's that have not been addressed are doing
260 * nothing.
261 *
262 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
263 * line low and then the SLAVE will release the SDA (data) line.
264 */
265 static int
iicbb_ack(device_t dev,int timeout)266 iicbb_ack(device_t dev, int timeout)
267 {
268 int noack;
269 int k = 0;
270
271 I2C_SET(dev,0,1);
272 I2C_SET(dev,1,1);
273 do {
274 noack = I2C_GETSDA(dev);
275 if (!noack)
276 break;
277 DELAY(10);
278 k += 10;
279 } while (k < timeout);
280
281 I2C_SET(dev,0,1);
282 I2C_DEBUG(printf("%c ",noack?'-':'+'));
283
284 return (noack);
285 }
286
287 static void
iicbb_sendbyte(device_t dev,u_char data,int timeout)288 iicbb_sendbyte(device_t dev, u_char data, int timeout)
289 {
290 int i;
291
292 for (i=7; i>=0; i--) {
293 if (data&(1<<i)) {
294 iicbb_one(dev, timeout);
295 } else {
296 iicbb_zero(dev, timeout);
297 }
298 }
299 I2C_DEBUG(printf("w%02x",(int)data));
300 return;
301 }
302
303 static u_char
iicbb_readbyte(device_t dev,int last,int timeout)304 iicbb_readbyte(device_t dev, int last, int timeout)
305 {
306 int i;
307 unsigned char data=0;
308
309 I2C_SET(dev,0,1);
310 for (i=7; i>=0; i--)
311 {
312 I2C_SET(dev,1,1);
313 if (I2C_GETSDA(dev))
314 data |= (1<<i);
315 I2C_SET(dev,0,1);
316 }
317 if (last) {
318 iicbb_one(dev, timeout);
319 } else {
320 iicbb_zero(dev, timeout);
321 }
322 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
323 return data;
324 }
325
326 static int
iicbb_callback(device_t dev,int index,caddr_t data)327 iicbb_callback(device_t dev, int index, caddr_t data)
328 {
329 return (IICBB_CALLBACK(device_get_parent(dev), index, data));
330 }
331
332 static int
iicbb_reset(device_t dev,u_char speed,u_char addr,u_char * oldaddr)333 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
334 {
335 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
336 }
337
338 static int
iicbb_start(device_t dev,u_char slave,int timeout)339 iicbb_start(device_t dev, u_char slave, int timeout)
340 {
341 int error;
342
343 I2C_DEBUG(printf("<"));
344
345 I2C_SET(dev,1,1);
346 I2C_SET(dev,1,0);
347 I2C_SET(dev,0,0);
348
349 /* send address */
350 iicbb_sendbyte(dev, slave, timeout);
351
352 /* check for ack */
353 if (iicbb_ack(dev, timeout)) {
354 error = IIC_ENOACK;
355 goto error;
356 }
357
358 return(0);
359
360 error:
361 iicbb_stop(dev);
362 return (error);
363 }
364
365 static int
iicbb_stop(device_t dev)366 iicbb_stop(device_t dev)
367 {
368 I2C_SET(dev,0,0);
369 I2C_SET(dev,1,0);
370 I2C_SET(dev,1,1);
371 I2C_DEBUG(printf(">"));
372 return (0);
373 }
374
375 static int
iicbb_write(device_t dev,const char * buf,int len,int * sent,int timeout)376 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
377 {
378 int bytes, error = 0;
379
380 bytes = 0;
381 while (len) {
382 /* send byte */
383 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
384
385 /* check for ack */
386 if (iicbb_ack(dev, timeout)) {
387 error = IIC_ENOACK;
388 goto error;
389 }
390 bytes ++;
391 len --;
392 }
393
394 error:
395 *sent = bytes;
396 return (error);
397 }
398
399 static int
iicbb_read(device_t dev,char * buf,int len,int * read,int last,int delay)400 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
401 {
402 int bytes;
403
404 bytes = 0;
405 while (len) {
406 /* XXX should insert delay here */
407 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
408
409 bytes ++;
410 len --;
411 }
412
413 *read = bytes;
414 return (0);
415 }
416
417 static int
iicbb_transfer(device_t dev,struct iic_msg * msgs,uint32_t nmsgs)418 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
419 {
420 int error;
421
422 error = IICBB_PRE_XFER(device_get_parent(dev));
423 if (error)
424 return (error);
425
426 error = iicbus_transfer_gen(dev, msgs, nmsgs);
427
428 IICBB_POST_XFER(device_get_parent(dev));
429 return (error);
430 }
431
432 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
433
434 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
435 MODULE_VERSION(iicbb, IICBB_MODVER);
436