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("$FreeBSD$");
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
69 struct iicbb_softc {
70 device_t iicbus;
71 int udelay; /* signal toggle delay in usec */
72 };
73
74 static int iicbb_attach(device_t);
75 static void iicbb_child_detached(device_t, device_t);
76 static int iicbb_detach(device_t);
77 static int iicbb_print_child(device_t, device_t);
78 static int iicbb_probe(device_t);
79
80 static int iicbb_callback(device_t, int, caddr_t);
81 static int iicbb_start(device_t, u_char, int);
82 static int iicbb_stop(device_t);
83 static int iicbb_write(device_t, const char *, int, int *, int);
84 static int iicbb_read(device_t, char *, int, int *, int, int);
85 static int iicbb_reset(device_t, u_char, u_char, u_char *);
86 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
87 #ifdef FDT
88 static phandle_t iicbb_get_node(device_t, device_t);
89 #endif
90
91 static 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
119 driver_t iicbb_driver = {
120 "iicbb",
121 iicbb_methods,
122 sizeof(struct iicbb_softc),
123 };
124
125 devclass_t iicbb_devclass;
126
127 static int
iicbb_probe(device_t dev)128 iicbb_probe(device_t dev)
129 {
130 device_set_desc(dev, "I2C bit-banging driver");
131
132 return (0);
133 }
134
135 static int
iicbb_attach(device_t dev)136 iicbb_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
149 static int
iicbb_detach(device_t dev)150 iicbb_detach(device_t dev)
151 {
152
153 bus_generic_detach(dev);
154 device_delete_children(dev);
155
156 return (0);
157 }
158
159 #ifdef FDT
160 static phandle_t
iicbb_get_node(device_t bus,device_t dev)161 iicbb_get_node(device_t bus, device_t dev)
162 {
163
164 /* We only have one child, the I2C bus, which needs our own node. */
165 return (ofw_bus_get_node(bus));
166 }
167 #endif
168
169 static void
iicbb_child_detached(device_t dev,device_t child)170 iicbb_child_detached( device_t dev, device_t child )
171 {
172 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
173
174 if (child == sc->iicbus)
175 sc->iicbus = NULL;
176 }
177
178 static int
iicbb_print_child(device_t bus,device_t dev)179 iicbb_print_child(device_t bus, device_t dev)
180 {
181 int error;
182 int retval = 0;
183 u_char oldaddr;
184
185 retval += bus_print_child_header(bus, dev);
186 /* retrieve the interface I2C address */
187 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
188 if (error == IIC_ENOADDR) {
189 retval += printf(" on %s master-only\n",
190 device_get_nameunit(bus));
191 } else {
192 /* restore the address */
193 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
194
195 retval += printf(" on %s addr 0x%x\n",
196 device_get_nameunit(bus), oldaddr & 0xff);
197 }
198
199 return (retval);
200 }
201
202 #define I2C_SETSDA(sc,dev,val) do { \
203 IICBB_SETSDA(device_get_parent(dev), val); \
204 DELAY(sc->udelay); \
205 } while (0)
206
207 #define I2C_SETSCL(dev,val) do { \
208 iicbb_setscl(dev, val, 100); \
209 } while (0)
210
211 #define I2C_SET(sc,dev,ctrl,data) do { \
212 I2C_SETSCL(dev, ctrl); \
213 I2C_SETSDA(sc, dev, data); \
214 } while (0)
215
216 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
217
218 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
219
220 static int i2c_debug = 0;
221 #define I2C_DEBUG(x) do { \
222 if (i2c_debug) (x); \
223 } while (0)
224
225 #define I2C_LOG(format,args...) do { \
226 printf(format, args); \
227 } while (0)
228
229 static void
iicbb_setscl(device_t dev,int val,int timeout)230 iicbb_setscl(device_t dev, int val, int timeout)
231 {
232 struct iicbb_softc *sc = device_get_softc(dev);
233 int k = 0;
234
235 IICBB_SETSCL(device_get_parent(dev), val);
236 DELAY(sc->udelay);
237
238 while (val && !I2C_GETSCL(dev) && k++ < timeout) {
239 IICBB_SETSCL(device_get_parent(dev), val);
240 DELAY(sc->udelay);
241 }
242
243 return;
244 }
245
246 static void
iicbb_one(device_t dev,int timeout)247 iicbb_one(device_t dev, int timeout)
248 {
249 struct iicbb_softc *sc = device_get_softc(dev);
250
251 I2C_SET(sc,dev,0,1);
252 I2C_SET(sc,dev,1,1);
253 I2C_SET(sc,dev,0,1);
254 return;
255 }
256
257 static void
iicbb_zero(device_t dev,int timeout)258 iicbb_zero(device_t dev, int timeout)
259 {
260 struct iicbb_softc *sc = device_get_softc(dev);
261
262 I2C_SET(sc,dev,0,0);
263 I2C_SET(sc,dev,1,0);
264 I2C_SET(sc,dev,0,0);
265 return;
266 }
267
268 /*
269 * Waiting for ACKNOWLEDGE.
270 *
271 * When a chip is being addressed or has received data it will issue an
272 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
273 * (set it to high level) and then release the CLOCK line.
274 * Now it must wait for the SLAVE to pull the DATA line low.
275 * Actually on the bus this looks like a START condition so nothing happens
276 * because of the fact that the IC's that have not been addressed are doing
277 * nothing.
278 *
279 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
280 * line low and then the SLAVE will release the SDA (data) line.
281 */
282 static int
iicbb_ack(device_t dev,int timeout)283 iicbb_ack(device_t dev, int timeout)
284 {
285 struct iicbb_softc *sc = device_get_softc(dev);
286 int noack;
287 int k = 0;
288
289 I2C_SET(sc,dev,0,1);
290 I2C_SET(sc,dev,1,1);
291 do {
292 noack = I2C_GETSDA(dev);
293 if (!noack)
294 break;
295 DELAY(1);
296 k++;
297 } while (k < timeout);
298
299 I2C_SET(sc,dev,0,1);
300 I2C_DEBUG(printf("%c ",noack?'-':'+'));
301
302 return (noack);
303 }
304
305 static void
iicbb_sendbyte(device_t dev,u_char data,int timeout)306 iicbb_sendbyte(device_t dev, u_char data, int timeout)
307 {
308 int i;
309
310 for (i=7; i>=0; i--) {
311 if (data&(1<<i)) {
312 iicbb_one(dev, timeout);
313 } else {
314 iicbb_zero(dev, timeout);
315 }
316 }
317 I2C_DEBUG(printf("w%02x",(int)data));
318 return;
319 }
320
321 static u_char
iicbb_readbyte(device_t dev,int last,int timeout)322 iicbb_readbyte(device_t dev, int last, int timeout)
323 {
324 struct iicbb_softc *sc = device_get_softc(dev);
325 int i;
326 unsigned char data=0;
327
328 I2C_SET(sc,dev,0,1);
329 for (i=7; i>=0; i--)
330 {
331 I2C_SET(sc,dev,1,1);
332 if (I2C_GETSDA(dev))
333 data |= (1<<i);
334 I2C_SET(sc,dev,0,1);
335 }
336 if (last) {
337 iicbb_one(dev, timeout);
338 } else {
339 iicbb_zero(dev, timeout);
340 }
341 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
342 return data;
343 }
344
345 static int
iicbb_callback(device_t dev,int index,caddr_t data)346 iicbb_callback(device_t dev, int index, caddr_t data)
347 {
348 return (IICBB_CALLBACK(device_get_parent(dev), index, data));
349 }
350
351 static int
iicbb_reset(device_t dev,u_char speed,u_char addr,u_char * oldaddr)352 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
353 {
354 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
355 }
356
357 static int
iicbb_start(device_t dev,u_char slave,int timeout)358 iicbb_start(device_t dev, u_char slave, int timeout)
359 {
360 struct iicbb_softc *sc = device_get_softc(dev);
361 int error;
362
363 I2C_DEBUG(printf("<"));
364
365 I2C_SET(sc,dev,1,1);
366 I2C_SET(sc,dev,1,0);
367 I2C_SET(sc,dev,0,0);
368
369 /* send address */
370 iicbb_sendbyte(dev, slave, timeout);
371
372 /* check for ack */
373 if (iicbb_ack(dev, timeout)) {
374 error = IIC_ENOACK;
375 goto error;
376 }
377
378 return(0);
379
380 error:
381 iicbb_stop(dev);
382 return (error);
383 }
384
385 static int
iicbb_stop(device_t dev)386 iicbb_stop(device_t dev)
387 {
388 struct iicbb_softc *sc = device_get_softc(dev);
389
390 I2C_SET(sc,dev,0,0);
391 I2C_SET(sc,dev,1,0);
392 I2C_SET(sc,dev,1,1);
393 I2C_DEBUG(printf(">"));
394 I2C_DEBUG(printf("\n"));
395 return (0);
396 }
397
398 static int
iicbb_write(device_t dev,const char * buf,int len,int * sent,int timeout)399 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
400 {
401 int bytes, error = 0;
402
403 bytes = 0;
404 while (len) {
405 /* send byte */
406 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
407
408 /* check for ack */
409 if (iicbb_ack(dev, timeout)) {
410 error = IIC_ENOACK;
411 goto error;
412 }
413 bytes ++;
414 len --;
415 }
416
417 error:
418 *sent = bytes;
419 return (error);
420 }
421
422 static int
iicbb_read(device_t dev,char * buf,int len,int * read,int last,int delay)423 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
424 {
425 int bytes;
426
427 bytes = 0;
428 while (len) {
429 /* XXX should insert delay here */
430 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
431
432 bytes ++;
433 len --;
434 }
435
436 *read = bytes;
437 return (0);
438 }
439
440 static int
iicbb_transfer(device_t dev,struct iic_msg * msgs,uint32_t nmsgs)441 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
442 {
443 int error;
444
445 error = IICBB_PRE_XFER(device_get_parent(dev));
446 if (error)
447 return (error);
448
449 error = iicbus_transfer_gen(dev, msgs, nmsgs);
450
451 IICBB_POST_XFER(device_get_parent(dev));
452 return (error);
453 }
454
455 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
456
457 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
458 MODULE_VERSION(iicbb, IICBB_MODVER);
459