1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1998, 2001 Nicolas Souchu
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 /*
33 * Generic I2C bit-banging code
34 *
35 * Example:
36 *
37 * iicbus
38 * / \
39 * iicbb pcf
40 * | \
41 * bti2c lpbb
42 *
43 * From Linux I2C generic interface
44 * (c) 1998 Gerd Knorr <[email protected]>
45 *
46 */
47
48 #include "opt_platform.h"
49
50 #include <sys/param.h>
51 #include <sys/kernel.h>
52 #include <sys/systm.h>
53 #include <sys/module.h>
54 #include <sys/bus.h>
55 #include <sys/uio.h>
56
57 #ifdef FDT
58 #include <dev/ofw/ofw_bus.h>
59 #include <dev/ofw/ofw_bus_subr.h>
60 #include <dev/fdt/fdt_common.h>
61 #endif
62
63 #include <dev/iicbus/iiconf.h>
64 #include <dev/iicbus/iicbus.h>
65
66 #include <dev/smbus/smbconf.h>
67
68 #include "iicbus_if.h"
69 #include "iicbb_if.h"
70
71 struct iicbb_softc {
72 device_t iicbus;
73 int udelay; /* signal toggle delay in usec */
74 };
75
76 static int iicbb_attach(device_t);
77 static void iicbb_child_detached(device_t, device_t);
78 static int iicbb_detach(device_t);
79 static int iicbb_print_child(device_t, device_t);
80 static int iicbb_probe(device_t);
81
82 static int iicbb_callback(device_t, int, caddr_t);
83 static int iicbb_start(device_t, u_char, int);
84 static int iicbb_stop(device_t);
85 static int iicbb_write(device_t, const char *, int, int *, int);
86 static int iicbb_read(device_t, char *, int, int *, int, int);
87 static int iicbb_reset(device_t, u_char, u_char, u_char *);
88 static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
89 #ifdef FDT
90 static phandle_t iicbb_get_node(device_t, device_t);
91 #endif
92
93 static device_method_t iicbb_methods[] = {
94 /* device interface */
95 DEVMETHOD(device_probe, iicbb_probe),
96 DEVMETHOD(device_attach, iicbb_attach),
97 DEVMETHOD(device_detach, iicbb_detach),
98
99 /* bus interface */
100 DEVMETHOD(bus_child_detached, iicbb_child_detached),
101 DEVMETHOD(bus_print_child, iicbb_print_child),
102
103 /* iicbus interface */
104 DEVMETHOD(iicbus_callback, iicbb_callback),
105 DEVMETHOD(iicbus_start, iicbb_start),
106 DEVMETHOD(iicbus_repeated_start, iicbb_start),
107 DEVMETHOD(iicbus_stop, iicbb_stop),
108 DEVMETHOD(iicbus_write, iicbb_write),
109 DEVMETHOD(iicbus_read, iicbb_read),
110 DEVMETHOD(iicbus_reset, iicbb_reset),
111 DEVMETHOD(iicbus_transfer, iicbb_transfer),
112
113 #ifdef FDT
114 /* ofw_bus interface */
115 DEVMETHOD(ofw_bus_get_node, iicbb_get_node),
116 #endif
117
118 { 0, 0 }
119 };
120
121 driver_t iicbb_driver = {
122 "iicbb",
123 iicbb_methods,
124 sizeof(struct iicbb_softc),
125 };
126
127 devclass_t iicbb_devclass;
128
129 static int
iicbb_probe(device_t dev)130 iicbb_probe(device_t dev)
131 {
132 device_set_desc(dev, "I2C bit-banging driver");
133
134 return (0);
135 }
136
137 static int
iicbb_attach(device_t dev)138 iicbb_attach(device_t dev)
139 {
140 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
141
142 sc->iicbus = device_add_child(dev, "iicbus", -1);
143 if (!sc->iicbus)
144 return (ENXIO);
145 sc->udelay = 10; /* 10 uS default */
146 bus_generic_attach(dev);
147
148 return (0);
149 }
150
151 static int
iicbb_detach(device_t dev)152 iicbb_detach(device_t dev)
153 {
154
155 bus_generic_detach(dev);
156 device_delete_children(dev);
157
158 return (0);
159 }
160
161 #ifdef FDT
162 static phandle_t
iicbb_get_node(device_t bus,device_t dev)163 iicbb_get_node(device_t bus, device_t dev)
164 {
165
166 /* We only have one child, the I2C bus, which needs our own node. */
167 return (ofw_bus_get_node(bus));
168 }
169 #endif
170
171 static void
iicbb_child_detached(device_t dev,device_t child)172 iicbb_child_detached( device_t dev, device_t child )
173 {
174 struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
175
176 if (child == sc->iicbus)
177 sc->iicbus = NULL;
178 }
179
180 static int
iicbb_print_child(device_t bus,device_t dev)181 iicbb_print_child(device_t bus, device_t dev)
182 {
183 int error;
184 int retval = 0;
185 u_char oldaddr;
186
187 retval += bus_print_child_header(bus, dev);
188 /* retrieve the interface I2C address */
189 error = IICBB_RESET(device_get_parent(bus), IIC_FASTEST, 0, &oldaddr);
190 if (error == IIC_ENOADDR) {
191 retval += printf(" on %s master-only\n",
192 device_get_nameunit(bus));
193 } else {
194 /* restore the address */
195 IICBB_RESET(device_get_parent(bus), IIC_FASTEST, oldaddr, NULL);
196
197 retval += printf(" on %s addr 0x%x\n",
198 device_get_nameunit(bus), oldaddr & 0xff);
199 }
200
201 return (retval);
202 }
203
204 #define I2C_SETSDA(sc,dev,val) do { \
205 IICBB_SETSDA(device_get_parent(dev), val); \
206 DELAY(sc->udelay); \
207 } while (0)
208
209 #define I2C_SETSCL(dev,val) do { \
210 iicbb_setscl(dev, val, 100); \
211 } while (0)
212
213 #define I2C_SET(sc,dev,ctrl,data) do { \
214 I2C_SETSCL(dev, ctrl); \
215 I2C_SETSDA(sc, dev, data); \
216 } while (0)
217
218 #define I2C_GETSDA(dev) (IICBB_GETSDA(device_get_parent(dev)))
219
220 #define I2C_GETSCL(dev) (IICBB_GETSCL(device_get_parent(dev)))
221
222 static int i2c_debug = 0;
223 #define I2C_DEBUG(x) do { \
224 if (i2c_debug) (x); \
225 } while (0)
226
227 #define I2C_LOG(format,args...) do { \
228 printf(format, args); \
229 } while (0)
230
231 static void
iicbb_setscl(device_t dev,int val,int timeout)232 iicbb_setscl(device_t dev, int val, int timeout)
233 {
234 struct iicbb_softc *sc = device_get_softc(dev);
235 int k = 0;
236
237 IICBB_SETSCL(device_get_parent(dev), val);
238 DELAY(sc->udelay);
239
240 while (val && !I2C_GETSCL(dev) && k++ < timeout) {
241 IICBB_SETSCL(device_get_parent(dev), val);
242 DELAY(sc->udelay);
243 }
244
245 return;
246 }
247
248 static void
iicbb_one(device_t dev,int timeout)249 iicbb_one(device_t dev, int timeout)
250 {
251 struct iicbb_softc *sc = device_get_softc(dev);
252
253 I2C_SET(sc,dev,0,1);
254 I2C_SET(sc,dev,1,1);
255 I2C_SET(sc,dev,0,1);
256 return;
257 }
258
259 static void
iicbb_zero(device_t dev,int timeout)260 iicbb_zero(device_t dev, int timeout)
261 {
262 struct iicbb_softc *sc = device_get_softc(dev);
263
264 I2C_SET(sc,dev,0,0);
265 I2C_SET(sc,dev,1,0);
266 I2C_SET(sc,dev,0,0);
267 return;
268 }
269
270 /*
271 * Waiting for ACKNOWLEDGE.
272 *
273 * When a chip is being addressed or has received data it will issue an
274 * ACKNOWLEDGE pulse. Therefore the MASTER must release the DATA line
275 * (set it to high level) and then release the CLOCK line.
276 * Now it must wait for the SLAVE to pull the DATA line low.
277 * Actually on the bus this looks like a START condition so nothing happens
278 * because of the fact that the IC's that have not been addressed are doing
279 * nothing.
280 *
281 * When the SLAVE has pulled this line low the MASTER will take the CLOCK
282 * line low and then the SLAVE will release the SDA (data) line.
283 */
284 static int
iicbb_ack(device_t dev,int timeout)285 iicbb_ack(device_t dev, int timeout)
286 {
287 struct iicbb_softc *sc = device_get_softc(dev);
288 int noack;
289 int k = 0;
290
291 I2C_SET(sc,dev,0,1);
292 I2C_SET(sc,dev,1,1);
293 do {
294 noack = I2C_GETSDA(dev);
295 if (!noack)
296 break;
297 DELAY(1);
298 k++;
299 } while (k < timeout);
300
301 I2C_SET(sc,dev,0,1);
302 I2C_DEBUG(printf("%c ",noack?'-':'+'));
303
304 return (noack);
305 }
306
307 static void
iicbb_sendbyte(device_t dev,u_char data,int timeout)308 iicbb_sendbyte(device_t dev, u_char data, int timeout)
309 {
310 int i;
311
312 for (i=7; i>=0; i--) {
313 if (data&(1<<i)) {
314 iicbb_one(dev, timeout);
315 } else {
316 iicbb_zero(dev, timeout);
317 }
318 }
319 I2C_DEBUG(printf("w%02x",(int)data));
320 return;
321 }
322
323 static u_char
iicbb_readbyte(device_t dev,int last,int timeout)324 iicbb_readbyte(device_t dev, int last, int timeout)
325 {
326 struct iicbb_softc *sc = device_get_softc(dev);
327 int i;
328 unsigned char data=0;
329
330 I2C_SET(sc,dev,0,1);
331 for (i=7; i>=0; i--)
332 {
333 I2C_SET(sc,dev,1,1);
334 if (I2C_GETSDA(dev))
335 data |= (1<<i);
336 I2C_SET(sc,dev,0,1);
337 }
338 if (last) {
339 iicbb_one(dev, timeout);
340 } else {
341 iicbb_zero(dev, timeout);
342 }
343 I2C_DEBUG(printf("r%02x%c ",(int)data,last?'-':'+'));
344 return data;
345 }
346
347 static int
iicbb_callback(device_t dev,int index,caddr_t data)348 iicbb_callback(device_t dev, int index, caddr_t data)
349 {
350 return (IICBB_CALLBACK(device_get_parent(dev), index, data));
351 }
352
353 static int
iicbb_reset(device_t dev,u_char speed,u_char addr,u_char * oldaddr)354 iicbb_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
355 {
356 return (IICBB_RESET(device_get_parent(dev), speed, addr, oldaddr));
357 }
358
359 static int
iicbb_start(device_t dev,u_char slave,int timeout)360 iicbb_start(device_t dev, u_char slave, int timeout)
361 {
362 struct iicbb_softc *sc = device_get_softc(dev);
363 int error;
364
365 I2C_DEBUG(printf("<"));
366
367 I2C_SET(sc,dev,1,1);
368 I2C_SET(sc,dev,1,0);
369 I2C_SET(sc,dev,0,0);
370
371 /* send address */
372 iicbb_sendbyte(dev, slave, timeout);
373
374 /* check for ack */
375 if (iicbb_ack(dev, timeout)) {
376 error = IIC_ENOACK;
377 goto error;
378 }
379
380 return(0);
381
382 error:
383 iicbb_stop(dev);
384 return (error);
385 }
386
387 static int
iicbb_stop(device_t dev)388 iicbb_stop(device_t dev)
389 {
390 struct iicbb_softc *sc = device_get_softc(dev);
391
392 I2C_SET(sc,dev,0,0);
393 I2C_SET(sc,dev,1,0);
394 I2C_SET(sc,dev,1,1);
395 I2C_DEBUG(printf(">"));
396 I2C_DEBUG(printf("\n"));
397 return (0);
398 }
399
400 static int
iicbb_write(device_t dev,const char * buf,int len,int * sent,int timeout)401 iicbb_write(device_t dev, const char *buf, int len, int *sent, int timeout)
402 {
403 int bytes, error = 0;
404
405 bytes = 0;
406 while (len) {
407 /* send byte */
408 iicbb_sendbyte(dev,(u_char)*buf++, timeout);
409
410 /* check for ack */
411 if (iicbb_ack(dev, timeout)) {
412 error = IIC_ENOACK;
413 goto error;
414 }
415 bytes ++;
416 len --;
417 }
418
419 error:
420 *sent = bytes;
421 return (error);
422 }
423
424 static int
iicbb_read(device_t dev,char * buf,int len,int * read,int last,int delay)425 iicbb_read(device_t dev, char * buf, int len, int *read, int last, int delay)
426 {
427 int bytes;
428
429 bytes = 0;
430 while (len) {
431 /* XXX should insert delay here */
432 *buf++ = (char)iicbb_readbyte(dev, (len == 1) ? last : 0, delay);
433
434 bytes ++;
435 len --;
436 }
437
438 *read = bytes;
439 return (0);
440 }
441
442 static int
iicbb_transfer(device_t dev,struct iic_msg * msgs,uint32_t nmsgs)443 iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
444 {
445 int error;
446
447 error = IICBB_PRE_XFER(device_get_parent(dev));
448 if (error)
449 return (error);
450
451 error = iicbus_transfer_gen(dev, msgs, nmsgs);
452
453 IICBB_POST_XFER(device_get_parent(dev));
454 return (error);
455 }
456
457 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
458
459 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
460 MODULE_VERSION(iicbb, IICBB_MODVER);
461