aboutsummaryrefslogtreecommitdiff
path: root/arch/cris/arch-v10/drivers/eeprom.c
blob: be35a70798aa5cc008807e6cc7488ba45f0d24dc (plain)
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
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
/*!*****************************************************************************
*!
*!  Implements an interface for i2c compatible eeproms to run under Linux.
*!  Supports 2k, 8k(?) and 16k. Uses adaptive timing adjustments by
*!  Johan.Adolfsson@axis.com
*!
*!  Probing results:
*!    8k or not is detected (the assumes 2k or 16k)
*!    2k or 16k detected using test reads and writes.
*!
*!------------------------------------------------------------------------
*!  HISTORY
*!
*!  DATE          NAME              CHANGES
*!  ----          ----              -------
*!  Aug  28 1999  Edgar Iglesias    Initial Version
*!  Aug  31 1999  Edgar Iglesias    Allow simultaneous users.
*!  Sep  03 1999  Edgar Iglesias    Updated probe.
*!  Sep  03 1999  Edgar Iglesias    Added bail-out stuff if we get interrupted
*!                                  in the spin-lock.
*!
*!  $Log: eeprom.c,v $
*!  Revision 1.12  2005/06/19 17:06:46  starvik
*!  Merge of Linux 2.6.12.
*!
*!  Revision 1.11  2005/01/26 07:14:46  starvik
*!  Applied diff from kernel janitors (Nish Aravamudan).
*!
*!  Revision 1.10  2003/09/11 07:29:48  starvik
*!  Merge of Linux 2.6.0-test5
*!
*!  Revision 1.9  2003/07/04 08:27:37  starvik
*!  Merge of Linux 2.5.74
*!
*!  Revision 1.8  2003/04/09 05:20:47  starvik
*!  Merge of Linux 2.5.67
*!
*!  Revision 1.6  2003/02/10 07:19:28  starvik
*!  Removed misplaced ;
*!
*!  Revision 1.5  2002/12/11 13:13:57  starvik
*!  Added arch/ to v10 specific includes
*!  Added fix from Linux 2.4 in serial.c (flush_to_flip_buffer)
*!
*!  Revision 1.4  2002/11/20 11:56:10  starvik
*!  Merge of Linux 2.5.48
*!
*!  Revision 1.3  2002/11/18 13:16:06  starvik
*!  Linux 2.5 port of latest 2.4 drivers
*!
*!  Revision 1.8  2001/06/15 13:24:29  jonashg
*!  * Added verification of pointers from userspace in read and write.
*!  * Made busy counter volatile.
*!  * Added define for initial write delay.
*!  * Removed warnings by using loff_t instead of unsigned long.
*!
*!  Revision 1.7  2001/06/14 15:26:54  jonashg
*!  Removed test because condition is always true.
*!
*!  Revision 1.6  2001/06/14 15:18:20  jonashg
*!  Kb -> kB (makes quite a difference if you don't know if you have 2k or 16k).
*!
*!  Revision 1.5  2001/06/14 14:39:51  jonashg
*!  Forgot to use name when registering the driver.
*!
*!  Revision 1.4  2001/06/14 14:35:47  jonashg
*!  * Gave driver a name and used it in printk's.
*!  * Cleanup.
*!
*!  Revision 1.3  2001/03/19 16:04:46  markusl
*!  Fixed init of fops struct
*!
*!  Revision 1.2  2001/03/19 10:35:07  markusl
*!  2.4 port of eeprom driver
*!
*!  Revision 1.8  2000/05/18 10:42:25  edgar
*!  Make sure to end write cycle on _every_ write
*!
*!  Revision 1.7  2000/01/17 17:41:01  johana
*!  Adjusted probing and return -ENOSPC when writing outside EEPROM
*!
*!  Revision 1.6  2000/01/17 15:50:36  johana
*!  Added adaptive timing adjustments and fixed autoprobing for 2k and 16k(?)
*!  EEPROMs
*!
*!  Revision 1.5  1999/09/03 15:07:37  edgar
*!  Added bail-out check to the spinlock
*!
*!  Revision 1.4  1999/09/03 12:11:17  bjornw
*!  Proper atomicity (need to use spinlocks, not if's). users -> busy.
*!
*!
*!        (c) 1999 Axis Communications AB, Lund, Sweden
*!*****************************************************************************/

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#include <asm/uaccess.h>
#include "i2c.h"

#define D(x) 

/* If we should use adaptive timing or not: */
//#define EEPROM_ADAPTIVE_TIMING      

#define EEPROM_MAJOR_NR 122  /* use a LOCAL/EXPERIMENTAL major for now */
#define EEPROM_MINOR_NR 0

/* Empirical sane initial value of the delay, the value will be adapted to
 * what the chip needs when using EEPROM_ADAPTIVE_TIMING.
 */
#define INITIAL_WRITEDELAY_US 4000
#define MAX_WRITEDELAY_US 10000 /* 10 ms according to spec for 2KB EEPROM */

/* This one defines how many times to try when eeprom fails. */
#define EEPROM_RETRIES 10

#define EEPROM_2KB (2 * 1024)
/*#define EEPROM_4KB (4 * 1024)*/ /* Exists but not used in Axis products */
#define EEPROM_8KB (8 * 1024 - 1 ) /* Last byte has write protection bit */
#define EEPROM_16KB (16 * 1024)

#define i2c_delay(x) udelay(x)

/*
 *  This structure describes the attached eeprom chip.
 *  The values are probed for.
 */

struct eeprom_type
{
  unsigned long size;
  unsigned long sequential_write_pagesize;
  unsigned char select_cmd;
  unsigned long usec_delay_writecycles; /* Min time between write cycles
					   (up to 10ms for some models) */
  unsigned long usec_delay_step; /* For adaptive algorithm */
  int adapt_state; /* 1 = To high , 0 = Even, -1 = To low */
  
  /* this one is to keep the read/write operations atomic */
  wait_queue_head_t wait_q;
  volatile int busy;
  int retry_cnt_addr; /* Used to keep track of number of retries for
                         adaptive timing adjustments */
  int retry_cnt_read;
};

static int  eeprom_open(struct inode * inode, struct file * file);
static loff_t  eeprom_lseek(struct file * file, loff_t offset, int orig);
static ssize_t  eeprom_read(struct file * file, char * buf, size_t count,
                            loff_t *off);
static ssize_t  eeprom_write(struct file * file, const char * buf, size_t count,
                             loff_t *off);
static int eeprom_close(struct inode * inode, struct file * file);

static int  eeprom_address(unsigned long addr);
static int  read_from_eeprom(char * buf, int count);
static int eeprom_write_buf(loff_t addr, const char * buf, int count);
static int eeprom_read_buf(loff_t addr, char * buf, int count);

static void eeprom_disable_write_protect(void);


static const char eeprom_name[] = "eeprom";

/* chip description */
static struct eeprom_type eeprom;

/* This is the exported file-operations structure for this device. */
const struct file_operations eeprom_fops =
{
  .llseek  = eeprom_lseek,
  .read    = eeprom_read,
  .write   = eeprom_write,
  .open    = eeprom_open,
  .release = eeprom_close
};

/* eeprom init call. Probes for different eeprom models. */

int __init eeprom_init(void)
{
  init_waitqueue_head(&eeprom.wait_q);
  eeprom.busy = 0;

#ifdef CONFIG_ETRAX_I2C_EEPROM_PROBE
#define EETEXT "Found"
#else
#define EETEXT "Assuming"
#endif
  if (register_chrdev(EEPROM_MAJOR_NR, eeprom_name, &eeprom_fops))
  {
    printk(KERN_INFO "%s: unable to get major %d for eeprom device\n",
           eeprom_name, EEPROM_MAJOR_NR);
    return -1;
  }
  
  printk("EEPROM char device v0.3, (c) 2000 Axis Communications AB\n");

  /*
   *  Note: Most of this probing method was taken from the printserver (5470e)
   *        codebase. It did not contain a way of finding the 16kB chips
   *        (M24128 or variants). The method used here might not work
   *        for all models. If you encounter problems the easiest way
   *        is probably to define your model within #ifdef's, and hard-
   *        code it.
   */

  eeprom.size = 0;
  eeprom.usec_delay_writecycles = INITIAL_WRITEDELAY_US;
  eeprom.usec_delay_step = 128;
  eeprom.adapt_state = 0;
  
#ifdef CONFIG_ETRAX_I2C_EEPROM_PROBE
  i2c_start();
  i2c_outbyte(0x80);
  if(!i2c_getack())
  {
    /* It's not 8k.. */
    int success = 0;
    unsigned char buf_2k_start[16];
    
    /* Im not sure this will work... :) */
    /* assume 2kB, if failure go for 16kB */
    /* Test with 16kB settings.. */
    /* If it's a 2kB EEPROM and we address it outside it's range
     * it will mirror the address space:
     * 1. We read two locations (that are mirrored), 
     *    if the content differs * it's a 16kB EEPROM.
     * 2. if it doesn't differ - write different value to one of the locations,
     *    check the other - if content still is the same it's a 2k EEPROM,
     *    restore original data.
     */
#define LOC1 8
#define LOC2 (0x1fb) /*1fb, 3ed, 5df, 7d1 */

   /* 2k settings */  
    i2c_stop();
    eeprom.size = EEPROM_2KB;
    eeprom.select_cmd = 0xA0;   
    eeprom.sequential_write_pagesize = 16;
    if( eeprom_read_buf( 0, buf_2k_start, 16 ) == 16 )
    {
      D(printk("2k start: '%16.16s'\n", buf_2k_start));
    }
    else
    {
      printk(KERN_INFO "%s: Failed to read in 2k mode!\n", eeprom_name);  
    }
    
    /* 16k settings */
    eeprom.size = EEPROM_16KB;
    eeprom.select_cmd = 0xA0;   
    eeprom.sequential_write_pagesize = 64;

    {
      unsigned char loc1[4], loc2[4], tmp[4];
      if( eeprom_read_buf(LOC2, loc2, 4) == 4)
      {
        if( eeprom_read_buf(LOC1, loc1, 4) == 4)
        {
          D(printk("0 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n", 
                   LOC1, loc1, LOC2, loc2));
#if 0
          if (memcmp(loc1, loc2, 4) != 0 )
          {
            /* It's 16k */
            printk(KERN_INFO "%s: 16k detected in step 1\n", eeprom_name);
            eeprom.size = EEPROM_16KB;     
            success = 1;
          }
          else
#endif
          {
            /* Do step 2 check */
            /* Invert value */
            loc1[0] = ~loc1[0];
            if (eeprom_write_buf(LOC1, loc1, 1) == 1)
            {
              /* If 2k EEPROM this write will actually write 10 bytes
               * from pos 0
               */
              D(printk("1 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n", 
                       LOC1, loc1, LOC2, loc2));
              if( eeprom_read_buf(LOC1, tmp, 4) == 4)
              {
                D(printk("2 loc1: (%i) '%4.4s' tmp '%4.4s'\n", 
                         LOC1, loc1, tmp));
                if (memcmp(loc1, tmp, 4) != 0 )
                {
                  printk(KERN_INFO "%s: read and write differs! Not 16kB\n",
                         eeprom_name);
                  loc1[0] = ~loc1[0];
                  
                  if (eeprom_write_buf(LOC1, loc1, 1) == 1)
                  {
                    success = 1;
                  }
                  else
                  {
                    printk(KERN_INFO "%s: Restore 2k failed during probe,"
                           " EEPROM might be corrupt!\n", eeprom_name);
                    
                  }
                  i2c_stop();
                  /* Go to 2k mode and write original data */
                  eeprom.size = EEPROM_2KB;
                  eeprom.select_cmd = 0xA0;   
                  eeprom.sequential_write_pagesize = 16;
                  if( eeprom_write_buf(0, buf_2k_start, 16) == 16)
                  {
                  }
                  else
                  {
                    printk(KERN_INFO "%s: Failed to write back 2k start!\n",
                           eeprom_name);
                  }
                  
                  eeprom.size = EEPROM_2KB;
                }
              }
                
              if(!success)
              {
                if( eeprom_read_buf(LOC2, loc2, 1) == 1)
                {
                  D(printk("0 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n", 
                           LOC1, loc1, LOC2, loc2));
                  if (memcmp(loc1, loc2, 4) == 0 )
                  {
                    /* Data the same, must be mirrored -> 2k */
                    /* Restore data */
                    printk(KERN_INFO "%s: 2k detected in step 2\n", eeprom_name);
                    loc1[0] = ~loc1[0];
                    if (eeprom_write_buf(LOC1, loc1, 1) == 1)
                    {
                      success = 1;
                    }
                    else
                    {
                      printk(KERN_INFO "%s: Restore 2k failed during probe,"
                             " EEPROM might be corrupt!\n", eeprom_name);
                      
                    }
                    
                    eeprom.size = EEPROM_2KB;     
                  }
                  else
                  {
                    printk(KERN_INFO "%s: 16k detected in step 2\n",
                           eeprom_name);
                    loc1[0] = ~loc1[0];
                    /* Data differs, assume 16k */
                    /* Restore data */
                    if (eeprom_write_buf(LOC1, loc1, 1) == 1)
                    {
                      success = 1;
                    }
                    else
                    {
                      printk(KERN_INFO "%s: Restore 16k failed during probe,"
                             " EEPROM might be corrupt!\n", eeprom_name);
                    }
                    
                    eeprom.size = EEPROM_16KB;
                  }
                }
              }
            }
          } /* read LOC1 */
        } /* address LOC1 */
        if (!success)
        {
          printk(KERN_INFO "%s: Probing failed!, using 2KB!\n", eeprom_name);
          eeprom.size = EEPROM_2KB;               
        }
      } /* read */
    }
  }
  else
  {
    i2c_outbyte(0x00);
    if(!i2c_getack())
    {
      /* No 8k */
      eeprom.size = EEPROM_2KB;
    }
    else
    {
      i2c_start();
      i2c_outbyte(0x81);
      if (!i2c_getack())
      {
        eeprom.size = EEPROM_2KB;
      }
      else
      {
        /* It's a 8kB */
        i2c_inbyte();
        eeprom.size = EEPROM_8KB;
      }
    }
  }
  i2c_stop();
#elif defined(CONFIG_ETRAX_I2C_EEPROM_16KB)
  eeprom.size = EEPROM_16KB;
#elif defined(CONFIG_ETRAX_I2C_EEPROM_8KB)
  eeprom.size = EEPROM_8KB;
#elif defined(CONFIG_ETRAX_I2C_EEPROM_2KB)
  eeprom.size = EEPROM_2KB;
#endif

  switch(eeprom.size)
  {
   case (EEPROM_2KB):
     printk("%s: " EETEXT " i2c compatible 2kB eeprom.\n", eeprom_name);
     eeprom.sequential_write_pagesize = 16;
     eeprom.select_cmd = 0xA0;
     break;
   case (EEPROM_8KB):
     printk("%s: " EETEXT " i2c compatible 8kB eeprom.\n", eeprom_name);
     eeprom.sequential_write_pagesize = 16;
     eeprom.select_cmd = 0x80;
     break;
   case (EEPROM_16KB):
     printk("%s: " EETEXT " i2c compatible 16kB eeprom.\n", eeprom_name);
     eeprom.sequential_write_pagesize = 64;
     eeprom.select_cmd = 0xA0;     
     break;
   default:
     eeprom.size = 0;
     printk("%s: Did not find a supported eeprom\n", eeprom_name);
     break;
  }

  

  eeprom_disable_write_protect();

  return 0;
}

/* Opens the device. */

static int eeprom_open(struct inode * inode, struct file * file)
{

  if(iminor(inode) != EEPROM_MINOR_NR)
     return -ENXIO;
  if(imajor(inode) != EEPROM_MAJOR_NR)
     return -ENXIO;

  if( eeprom.size > 0 )
  {
    /* OK */
    return 0;
  }

  /* No EEprom found */
  return -EFAULT;
}

/* Changes the current file position. */

static loff_t eeprom_lseek(struct file * file, loff_t offset, int orig)
{
/*
 *  orig 0: position from begning of eeprom
 *  orig 1: relative from current position
 *  orig 2: position from last eeprom address
 */
  
  switch (orig)
  {
   case 0:
     file->f_pos = offset;
     break;
   case 1:
     file->f_pos += offset;
     break;
   case 2:
     file->f_pos = eeprom.size - offset;
     break;
   default:
     return -EINVAL;
  }

  /* truncate position */
  if (file->f_pos < 0)
  {
    file->f_pos = 0;    
    return(-EOVERFLOW);
  }
  
  if (file->f_pos >= eeprom.size)
  {
    file->f_pos = eeprom.size - 1;
    return(-EOVERFLOW);
  }

  return ( file->f_pos );
}

/* Reads data from eeprom. */

static int eeprom_read_buf(loff_t addr, char * buf, int count)
{
  struct file f;

  f.f_pos = addr;
  return eeprom_read(&f, buf, count, &addr);
}



/* Reads data from eeprom. */

static ssize_t eeprom_read(struct file * file, char * buf, size_t count, loff_t *off)
{
  int read=0;
  unsigned long p = file->f_pos;

  unsigned char page;

  if(p >= eeprom.size)  /* Address i 0 - (size-1) */
  {
    return -EFAULT;
  }
  
  wait_event_interruptible(eeprom.wait_q, !eeprom.busy);
  if (signal_pending(current))
    return -EINTR;

  eeprom.busy++;

  page = (unsigned char) (p >> 8);
  
  if(!eeprom_address(p))
  {
    printk(KERN_INFO "%s: Read failed to address the eeprom: "
           "0x%08X (%i) page: %i\n", eeprom_name, (int)p, (int)p, page);
    i2c_stop();
    
    /* don't forget to wake them up */
    eeprom.busy--;
    wake_up_interruptible(&eeprom.wait_q);  
    return -EFAULT;
  }

  if( (p + count) > eeprom.size)
  {
    /* truncate count */
    count = eeprom.size - p;
  }

  /* stop dummy write op and initiate the read op */
  i2c_start();

  /* special case for small eeproms */
  if(eeprom.size < EEPROM_16KB)
  {
    i2c_outbyte( eeprom.select_cmd | 1 | (page << 1) );
  }

  /* go on with the actual read */
  read = read_from_eeprom( buf, count);
  
  if(read > 0)
  {
    file->f_pos += read;
  }

  eeprom.busy--;
  wake_up_interruptible(&eeprom.wait_q);
  return read;
}

/* Writes data to eeprom. */

static int eeprom_write_buf(loff_t addr, const char * buf, int count)
{
  struct file f;

  f.f_pos = addr;
  
  return eeprom_write(&f, buf, count, &addr);
}


/* Writes data to eeprom. */

static ssize_t eeprom_write(struct file * file, const char * buf, size_t count,
                            loff_t *off)
{
  int i, written, restart=1;
  unsigned long p;

  if (!access_ok(VERIFY_READ, buf, count))
  {
    return -EFAULT;
  }

  wait_event_interruptible(eeprom.wait_q, !eeprom.busy);
  /* bail out if we get interrupted */
  if (signal_pending(current))
    return -EINTR;
  eeprom.busy++;
  for(i = 0; (i < EEPROM_RETRIES) && (restart > 0); i++)
  {
    restart = 0;
    written = 0;
    p = file->f_pos;
   
    
    while( (written < count) && (p < eeprom.size))
    {
      /* address the eeprom */
      if(!eeprom_address(p))
      {
        printk(KERN_INFO "%s: Write failed to address the eeprom: "
               "0x%08X (%i) \n", eeprom_name, (int)p, (int)p);
        i2c_stop();
        
        /* don't forget to wake them up */
        eeprom.busy--;
        wake_up_interruptible(&eeprom.wait_q);
        return -EFAULT;
      }
#ifdef EEPROM_ADAPTIVE_TIMING      
      /* Adaptive algorithm to adjust timing */
      if (eeprom.retry_cnt_addr > 0)
      {
        /* To Low now */
        D(printk(">D=%i d=%i\n",
               eeprom.usec_delay_writecycles, eeprom.usec_delay_step));

        if (eeprom.usec_delay_step < 4)
        {
          eeprom.usec_delay_step++;
          eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
        }
        else
        {

          if (eeprom.adapt_state > 0)
          {
            /* To Low before */
            eeprom.usec_delay_step *= 2;
            if (eeprom.usec_delay_step > 2)
            {
              eeprom.usec_delay_step--;
            }
            eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
          }
          else if (eeprom.adapt_state < 0)
          {
            /* To High before (toggle dir) */
            eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
            if (eeprom.usec_delay_step > 1)
            {
              eeprom.usec_delay_step /= 2;
              eeprom.usec_delay_step--;
            }
          }
        }

        eeprom.adapt_state = 1;
      }
      else
      {
        /* To High (or good) now */
        D(printk("<D=%i d=%i\n",
               eeprom.usec_delay_writecycles, eeprom.usec_delay_step));
        
        if (eeprom.adapt_state < 0)
        {
          /* To High before */
          if (eeprom.usec_delay_step > 1)
          {
            eeprom.usec_delay_step *= 2;
            eeprom.usec_delay_step--;
            
            if (eeprom.usec_delay_writecycles > eeprom.usec_delay_step)
            {
              eeprom.usec_delay_writecycles -= eeprom.usec_delay_step;
            }
          }
        }
        else if (eeprom.adapt_state > 0)
        {
          /* To Low before (toggle dir) */
          if (eeprom.usec_delay_writecycles > eeprom.usec_delay_step)
          {
            eeprom.usec_delay_writecycles -= eeprom.usec_delay_step;
          }
          if (eeprom.usec_delay_step > 1)
          {
            eeprom.usec_delay_step /= 2;
            eeprom.usec_delay_step--;
          }
          
          eeprom.adapt_state = -1;
        }

        if (eeprom.adapt_state > -100)
        {
          eeprom.adapt_state--;
        }
        else
        {
          /* Restart adaption */
          D(printk("#Restart\n"));
          eeprom.usec_delay_step++;
        }
      }
#endif /* EEPROM_ADAPTIVE_TIMING */
      /* write until we hit a page boundary or count */
      do
      {
        i2c_outbyte(buf[written]);        
        if(!i2c_getack())
        {
          restart=1;
          printk(KERN_INFO "%s: write error, retrying. %d\n", eeprom_name, i);
          i2c_stop();
          break;
        }
        written++;
        p++;        
      } while( written < count && ( p % eeprom.sequential_write_pagesize ));

      /* end write cycle */
      i2c_stop();
      i2c_delay(eeprom.usec_delay_writecycles);
    } /* while */
  } /* for  */

  eeprom.busy--;
  wake_up_interruptible(&eeprom.wait_q);
  if (written == 0 && file->f_pos >= eeprom.size){
    return -ENOSPC;
  }
  file->f_pos += written;
  return written;
}

/* Closes the device. */

static int eeprom_close(struct inode * inode, struct file * file)
{
  /* do nothing for now */
  return 0;
}

/* Sets the current address of the eeprom. */

static int eeprom_address(unsigned long addr)
{
  int i;
  unsigned char page, offset;

  page   = (unsigned char) (addr >> 8);
  offset = (unsigned char)  addr;

  for(i = 0; i < EEPROM_RETRIES; i++)
  {
    /* start a dummy write for addressing */
    i2c_start();

    if(eeprom.size == EEPROM_16KB)
    {
      i2c_outbyte( eeprom.select_cmd ); 
      i2c_getack();
      i2c_outbyte(page); 
    }
    else
    {
      i2c_outbyte( eeprom.select_cmd | (page << 1) ); 
    }
    if(!i2c_getack())
    {
      /* retry */
      i2c_stop();
      /* Must have a delay here.. 500 works, >50, 100->works 5th time*/
      i2c_delay(MAX_WRITEDELAY_US / EEPROM_RETRIES * i);
      /* The chip needs up to 10 ms from write stop to next start */
     
    }
    else
    {
      i2c_outbyte(offset);
      
      if(!i2c_getack())
      {
        /* retry */
        i2c_stop();
      }
      else
        break;
    }
  }    

  
  eeprom.retry_cnt_addr = i;
  D(printk("%i\n", eeprom.retry_cnt_addr));
  if(eeprom.retry_cnt_addr == EEPROM_RETRIES)
  {
    /* failed */
    return 0;
  }
  return 1;
}

/* Reads from current address. */

static int read_from_eeprom(char * buf, int count)
{
  int i, read=0;

  for(i = 0; i < EEPROM_RETRIES; i++)
  {    
    if(eeprom.size == EEPROM_16KB)
    {
      i2c_outbyte( eeprom.select_cmd | 1 );
    }

    if(i2c_getack())
    {
      break;
    }
  }
  
  if(i == EEPROM_RETRIES)
  {
    printk(KERN_INFO "%s: failed to read from eeprom\n", eeprom_name);
    i2c_stop();
    
    return -EFAULT;
  }

  while( (read < count))
  {    
    if (put_user(i2c_inbyte(), &buf[read++]))
    {
      i2c_stop();

      return -EFAULT;
    }

    /*
     *  make sure we don't ack last byte or you will get very strange
     *  results!
     */
    if(read < count)
    {
      i2c_sendack();
    }
  }

  /* stop the operation */
  i2c_stop();

  return read;
}

/* Disables write protection if applicable. */

#define DBP_SAVE(x)
#define ax_printf printk
static void eeprom_disable_write_protect(void)
{
  /* Disable write protect */
  if (eeprom.size == EEPROM_8KB)
  {
    /* Step 1 Set WEL = 1 (write 00000010 to address 1FFFh */
    i2c_start();
    i2c_outbyte(0xbe);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false\n"));
    }
    i2c_outbyte(0xFF);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 2\n"));
    }
    i2c_outbyte(0x02);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 3\n"));
    }
    i2c_stop();

    i2c_delay(1000);

    /* Step 2 Set RWEL = 1 (write 00000110 to address 1FFFh */
    i2c_start();
    i2c_outbyte(0xbe);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 55\n"));
    }
    i2c_outbyte(0xFF);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 52\n"));
    }
    i2c_outbyte(0x06);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 53\n"));
    }
    i2c_stop();
    
    /* Step 3 Set BP1, BP0, and/or WPEN bits (write 00000110 to address 1FFFh */
    i2c_start();
    i2c_outbyte(0xbe);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 56\n"));
    }
    i2c_outbyte(0xFF);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 57\n"));
    }
    i2c_outbyte(0x06);
    if(!i2c_getack())
    {
      DBP_SAVE(ax_printf("Get ack returns false 58\n"));
    }
    i2c_stop();
    
    /* Write protect disabled */
  }
}

module_init(eeprom_init);