1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
|
/*!***************************************************************************
*!
*! FILE NAME : i2c.c
*!
*! DESCRIPTION: implements an interface for IIC/I2C, both directly from other
*! kernel modules (i2c_writereg/readreg) and from userspace using
*! ioctl()'s
*!
*! Nov 30 1998 Torbjorn Eliasson Initial version.
*! Bjorn Wesen Elinux kernel version.
*! Jan 14 2000 Johan Adolfsson Fixed PB shadow register stuff -
*! don't use PB_I2C if DS1302 uses same bits,
*! use PB.
*| June 23 2003 Pieter Grimmerink Added 'i2c_sendnack'. i2c_readreg now
*| generates nack on last received byte,
*| instead of ack.
*| i2c_getack changed data level while clock
*| was high, causing DS75 to see a stop condition
*!
*! ---------------------------------------------------------------------------
*!
*! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
*!
*!***************************************************************************/
/****************** INCLUDE FILES SECTION ***********************************/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <asm/etraxi2c.h>
#include <asm/io.h>
#include <asm/delay.h>
#include "i2c.h"
/****************** I2C DEFINITION SECTION *************************/
#define D(x)
#define I2C_MAJOR 123 /* LOCAL/EXPERIMENTAL */
static DEFINE_MUTEX(i2c_mutex);
static const char i2c_name[] = "i2c";
#define CLOCK_LOW_TIME 8
#define CLOCK_HIGH_TIME 8
#define START_CONDITION_HOLD_TIME 8
#define STOP_CONDITION_HOLD_TIME 8
#define ENABLE_OUTPUT 0x01
#define ENABLE_INPUT 0x00
#define I2C_CLOCK_HIGH 1
#define I2C_CLOCK_LOW 0
#define I2C_DATA_HIGH 1
#define I2C_DATA_LOW 0
#define i2c_enable()
#define i2c_disable()
/* enable or disable output-enable, to select output or input on the i2c bus */
#define i2c_dir_out() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_out)
#define i2c_dir_in() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_in)
/* control the i2c clock and data signals */
#define i2c_clk(x) crisv32_io_set(&cris_i2c_clk, x)
#define i2c_data(x) crisv32_io_set(&cris_i2c_data, x)
/* read a bit from the i2c interface */
#define i2c_getbit() crisv32_io_rd(&cris_i2c_data)
#define i2c_delay(usecs) udelay(usecs)
static DEFINE_SPINLOCK(i2c_lock); /* Protect directions etc */
/****************** VARIABLE SECTION ************************************/
static struct crisv32_iopin cris_i2c_clk;
static struct crisv32_iopin cris_i2c_data;
/****************** FUNCTION DEFINITION SECTION *************************/
/* generate i2c start condition */
void
i2c_start(void)
{
/*
* SCL=1 SDA=1
*/
i2c_dir_out();
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_data(I2C_DATA_HIGH);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
/*
* SCL=1 SDA=0
*/
i2c_data(I2C_DATA_LOW);
i2c_delay(START_CONDITION_HOLD_TIME);
/*
* SCL=0 SDA=0
*/
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
}
/* generate i2c stop condition */
void
i2c_stop(void)
{
i2c_dir_out();
/*
* SCL=0 SDA=0
*/
i2c_clk(I2C_CLOCK_LOW);
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_LOW_TIME*2);
/*
* SCL=1 SDA=0
*/
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME*2);
/*
* SCL=1 SDA=1
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(STOP_CONDITION_HOLD_TIME);
i2c_dir_in();
}
/* write a byte to the i2c interface */
void
i2c_outbyte(unsigned char x)
{
int i;
i2c_dir_out();
for (i = 0; i < 8; i++) {
if (x & 0x80) {
i2c_data(I2C_DATA_HIGH);
} else {
i2c_data(I2C_DATA_LOW);
}
i2c_delay(CLOCK_LOW_TIME/2);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME/2);
x <<= 1;
}
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_LOW_TIME/2);
/*
* enable input
*/
i2c_dir_in();
}
/* read a byte from the i2c interface */
unsigned char
i2c_inbyte(void)
{
unsigned char aBitByte = 0;
int i;
/* Switch off I2C to get bit */
i2c_disable();
i2c_dir_in();
i2c_delay(CLOCK_HIGH_TIME/2);
/* Get bit */
aBitByte |= i2c_getbit();
/* Enable I2C */
i2c_enable();
i2c_delay(CLOCK_LOW_TIME/2);
for (i = 1; i < 8; i++) {
aBitByte <<= 1;
/* Clock pulse */
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
/* Switch off I2C to get bit */
i2c_disable();
i2c_dir_in();
i2c_delay(CLOCK_HIGH_TIME/2);
/* Get bit */
aBitByte |= i2c_getbit();
/* Enable I2C */
i2c_enable();
i2c_delay(CLOCK_LOW_TIME/2);
}
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
/*
* we leave the clock low, getbyte is usually followed
* by sendack/nack, they assume the clock to be low
*/
i2c_clk(I2C_CLOCK_LOW);
return aBitByte;
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_getack
*#
*# DESCRIPTION : checks if ack was received from ic2
*#
*#--------------------------------------------------------------------------*/
int
i2c_getack(void)
{
int ack = 1;
/*
* enable output
*/
i2c_dir_out();
/*
* Release data bus by setting
* data high
*/
i2c_data(I2C_DATA_HIGH);
/*
* enable input
*/
i2c_dir_in();
i2c_delay(CLOCK_HIGH_TIME/4);
/*
* generate ACK clock pulse
*/
i2c_clk(I2C_CLOCK_HIGH);
#if 0
/*
* Use PORT PB instead of I2C
* for input. (I2C not working)
*/
i2c_clk(1);
i2c_data(1);
/*
* switch off I2C
*/
i2c_data(1);
i2c_disable();
i2c_dir_in();
#endif
/*
* now wait for ack
*/
i2c_delay(CLOCK_HIGH_TIME/2);
/*
* check for ack
*/
if (i2c_getbit())
ack = 0;
i2c_delay(CLOCK_HIGH_TIME/2);
if (!ack) {
if (!i2c_getbit()) /* receiver pulld SDA low */
ack = 1;
i2c_delay(CLOCK_HIGH_TIME/2);
}
/*
* our clock is high now, make sure data is low
* before we enable our output. If we keep data high
* and enable output, we would generate a stop condition.
*/
#if 0
i2c_data(I2C_DATA_LOW);
/*
* end clock pulse
*/
i2c_enable();
i2c_dir_out();
#endif
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_HIGH_TIME/4);
/*
* enable output
*/
i2c_dir_out();
/*
* remove ACK clock pulse
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(CLOCK_LOW_TIME/2);
return ack;
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: I2C::sendAck
*#
*# DESCRIPTION : Send ACK on received data
*#
*#--------------------------------------------------------------------------*/
void
i2c_sendack(void)
{
/*
* enable output
*/
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_out();
/*
* set ack pulse high
*/
i2c_data(I2C_DATA_LOW);
/*
* generate clock pulse
*/
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME/6);
/*
* reset data out
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_in();
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_sendnack
*#
*# DESCRIPTION : Sends NACK on received data
*#
*#--------------------------------------------------------------------------*/
void
i2c_sendnack(void)
{
/*
* enable output
*/
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_out();
/*
* set data high
*/
i2c_data(I2C_DATA_HIGH);
/*
* generate clock pulse
*/
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_in();
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_write
*#
*# DESCRIPTION : Writes a value to an I2C device
*#
*#--------------------------------------------------------------------------*/
int
i2c_write(unsigned char theSlave, void *data, size_t nbytes)
{
int error, cntr = 3;
unsigned char bytes_wrote = 0;
unsigned char value;
unsigned
|