1 /*!*****************************************************************************
3 *! Implements an interface for i2c compatible eeproms to run under Linux.
4 *! Supports 2k, 8k(?) and 16k. Uses adaptive timing adjustments by
5 *! Johan.Adolfsson@axis.com
8 *! 8k or not is detected (the assumes 2k or 16k)
9 *! 2k or 16k detected using test reads and writes.
11 *!------------------------------------------------------------------------
16 *! Aug 28 1999 Edgar Iglesias Initial Version
17 *! Aug 31 1999 Edgar Iglesias Allow simultaneous users.
18 *! Sep 03 1999 Edgar Iglesias Updated probe.
19 *! Sep 03 1999 Edgar Iglesias Added bail-out stuff if we get interrupted
22 *! (c) 1999 Axis Communications AB, Lund, Sweden
23 *!*****************************************************************************/
25 #include <linux/kernel.h>
26 #include <linux/sched.h>
28 #include <linux/init.h>
29 #include <linux/delay.h>
30 #include <linux/interrupt.h>
31 #include <linux/wait.h>
32 #include <asm/uaccess.h>
37 /* If we should use adaptive timing or not: */
38 /* #define EEPROM_ADAPTIVE_TIMING */
40 #define EEPROM_MAJOR_NR 122 /* use a LOCAL/EXPERIMENTAL major for now */
41 #define EEPROM_MINOR_NR 0
43 /* Empirical sane initial value of the delay, the value will be adapted to
44 * what the chip needs when using EEPROM_ADAPTIVE_TIMING.
46 #define INITIAL_WRITEDELAY_US 4000
47 #define MAX_WRITEDELAY_US 10000 /* 10 ms according to spec for 2KB EEPROM */
49 /* This one defines how many times to try when eeprom fails. */
50 #define EEPROM_RETRIES 10
52 #define EEPROM_2KB (2 * 1024)
53 /*#define EEPROM_4KB (4 * 1024)*/ /* Exists but not used in Axis products */
54 #define EEPROM_8KB (8 * 1024 - 1 ) /* Last byte has write protection bit */
55 #define EEPROM_16KB (16 * 1024)
57 #define i2c_delay(x) udelay(x)
60 * This structure describes the attached eeprom chip.
61 * The values are probed for.
67 unsigned long sequential_write_pagesize
;
68 unsigned char select_cmd
;
69 unsigned long usec_delay_writecycles
; /* Min time between write cycles
70 (up to 10ms for some models) */
71 unsigned long usec_delay_step
; /* For adaptive algorithm */
72 int adapt_state
; /* 1 = To high , 0 = Even, -1 = To low */
74 /* this one is to keep the read/write operations atomic */
76 int retry_cnt_addr
; /* Used to keep track of number of retries for
77 adaptive timing adjustments */
81 static int eeprom_open(struct inode
* inode
, struct file
* file
);
82 static loff_t
eeprom_lseek(struct file
* file
, loff_t offset
, int orig
);
83 static ssize_t
eeprom_read(struct file
* file
, char * buf
, size_t count
,
85 static ssize_t
eeprom_write(struct file
* file
, const char * buf
, size_t count
,
87 static int eeprom_close(struct inode
* inode
, struct file
* file
);
89 static int eeprom_address(unsigned long addr
);
90 static int read_from_eeprom(char * buf
, int count
);
91 static int eeprom_write_buf(loff_t addr
, const char * buf
, int count
);
92 static int eeprom_read_buf(loff_t addr
, char * buf
, int count
);
94 static void eeprom_disable_write_protect(void);
97 static const char eeprom_name
[] = "eeprom";
99 /* chip description */
100 static struct eeprom_type eeprom
;
102 /* This is the exported file-operations structure for this device. */
103 const struct file_operations eeprom_fops
=
105 .llseek
= eeprom_lseek
,
107 .write
= eeprom_write
,
109 .release
= eeprom_close
112 /* eeprom init call. Probes for different eeprom models. */
114 int __init
eeprom_init(void)
116 mutex_init(&eeprom
.lock
);
118 #ifdef CONFIG_ETRAX_I2C_EEPROM_PROBE
119 #define EETEXT "Found"
121 #define EETEXT "Assuming"
123 if (register_chrdev(EEPROM_MAJOR_NR
, eeprom_name
, &eeprom_fops
))
125 printk(KERN_INFO
"%s: unable to get major %d for eeprom device\n",
126 eeprom_name
, EEPROM_MAJOR_NR
);
130 printk("EEPROM char device v0.3, (c) 2000 Axis Communications AB\n");
133 * Note: Most of this probing method was taken from the printserver (5470e)
134 * codebase. It did not contain a way of finding the 16kB chips
135 * (M24128 or variants). The method used here might not work
136 * for all models. If you encounter problems the easiest way
137 * is probably to define your model within #ifdef's, and hard-
142 eeprom
.usec_delay_writecycles
= INITIAL_WRITEDELAY_US
;
143 eeprom
.usec_delay_step
= 128;
144 eeprom
.adapt_state
= 0;
146 #ifdef CONFIG_ETRAX_I2C_EEPROM_PROBE
153 unsigned char buf_2k_start
[16];
155 /* Im not sure this will work... :) */
156 /* assume 2kB, if failure go for 16kB */
157 /* Test with 16kB settings.. */
158 /* If it's a 2kB EEPROM and we address it outside it's range
159 * it will mirror the address space:
160 * 1. We read two locations (that are mirrored),
161 * if the content differs * it's a 16kB EEPROM.
162 * 2. if it doesn't differ - write different value to one of the locations,
163 * check the other - if content still is the same it's a 2k EEPROM,
164 * restore original data.
167 #define LOC2 (0x1fb) /*1fb, 3ed, 5df, 7d1 */
171 eeprom
.size
= EEPROM_2KB
;
172 eeprom
.select_cmd
= 0xA0;
173 eeprom
.sequential_write_pagesize
= 16;
174 if( eeprom_read_buf( 0, buf_2k_start
, 16 ) == 16 )
176 D(printk("2k start: '%16.16s'\n", buf_2k_start
));
180 printk(KERN_INFO
"%s: Failed to read in 2k mode!\n", eeprom_name
);
184 eeprom
.size
= EEPROM_16KB
;
185 eeprom
.select_cmd
= 0xA0;
186 eeprom
.sequential_write_pagesize
= 64;
189 unsigned char loc1
[4], loc2
[4], tmp
[4];
190 if( eeprom_read_buf(LOC2
, loc2
, 4) == 4)
192 if( eeprom_read_buf(LOC1
, loc1
, 4) == 4)
194 D(printk("0 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n",
195 LOC1
, loc1
, LOC2
, loc2
));
197 if (memcmp(loc1
, loc2
, 4) != 0 )
200 printk(KERN_INFO
"%s: 16k detected in step 1\n", eeprom_name
);
201 eeprom
.size
= EEPROM_16KB
;
207 /* Do step 2 check */
210 if (eeprom_write_buf(LOC1
, loc1
, 1) == 1)
212 /* If 2k EEPROM this write will actually write 10 bytes
215 D(printk("1 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n",
216 LOC1
, loc1
, LOC2
, loc2
));
217 if( eeprom_read_buf(LOC1
, tmp
, 4) == 4)
219 D(printk("2 loc1: (%i) '%4.4s' tmp '%4.4s'\n",
221 if (memcmp(loc1
, tmp
, 4) != 0 )
223 printk(KERN_INFO
"%s: read and write differs! Not 16kB\n",
227 if (eeprom_write_buf(LOC1
, loc1
, 1) == 1)
233 printk(KERN_INFO
"%s: Restore 2k failed during probe,"
234 " EEPROM might be corrupt!\n", eeprom_name
);
238 /* Go to 2k mode and write original data */
239 eeprom
.size
= EEPROM_2KB
;
240 eeprom
.select_cmd
= 0xA0;
241 eeprom
.sequential_write_pagesize
= 16;
242 if( eeprom_write_buf(0, buf_2k_start
, 16) == 16)
247 printk(KERN_INFO
"%s: Failed to write back 2k start!\n",
251 eeprom
.size
= EEPROM_2KB
;
257 if( eeprom_read_buf(LOC2
, loc2
, 1) == 1)
259 D(printk("0 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n",
260 LOC1
, loc1
, LOC2
, loc2
));
261 if (memcmp(loc1
, loc2
, 4) == 0 )
263 /* Data the same, must be mirrored -> 2k */
265 printk(KERN_INFO
"%s: 2k detected in step 2\n", eeprom_name
);
267 if (eeprom_write_buf(LOC1
, loc1
, 1) == 1)
273 printk(KERN_INFO
"%s: Restore 2k failed during probe,"
274 " EEPROM might be corrupt!\n", eeprom_name
);
278 eeprom
.size
= EEPROM_2KB
;
282 printk(KERN_INFO
"%s: 16k detected in step 2\n",
285 /* Data differs, assume 16k */
287 if (eeprom_write_buf(LOC1
, loc1
, 1) == 1)
293 printk(KERN_INFO
"%s: Restore 16k failed during probe,"
294 " EEPROM might be corrupt!\n", eeprom_name
);
297 eeprom
.size
= EEPROM_16KB
;
306 printk(KERN_INFO
"%s: Probing failed!, using 2KB!\n", eeprom_name
);
307 eeprom
.size
= EEPROM_2KB
;
318 eeprom
.size
= EEPROM_2KB
;
326 eeprom
.size
= EEPROM_2KB
;
332 eeprom
.size
= EEPROM_8KB
;
337 #elif defined(CONFIG_ETRAX_I2C_EEPROM_16KB)
338 eeprom
.size
= EEPROM_16KB
;
339 #elif defined(CONFIG_ETRAX_I2C_EEPROM_8KB)
340 eeprom
.size
= EEPROM_8KB
;
341 #elif defined(CONFIG_ETRAX_I2C_EEPROM_2KB)
342 eeprom
.size
= EEPROM_2KB
;
348 printk("%s: " EETEXT
" i2c compatible 2kB eeprom.\n", eeprom_name
);
349 eeprom
.sequential_write_pagesize
= 16;
350 eeprom
.select_cmd
= 0xA0;
353 printk("%s: " EETEXT
" i2c compatible 8kB eeprom.\n", eeprom_name
);
354 eeprom
.sequential_write_pagesize
= 16;
355 eeprom
.select_cmd
= 0x80;
358 printk("%s: " EETEXT
" i2c compatible 16kB eeprom.\n", eeprom_name
);
359 eeprom
.sequential_write_pagesize
= 64;
360 eeprom
.select_cmd
= 0xA0;
364 printk("%s: Did not find a supported eeprom\n", eeprom_name
);
370 eeprom_disable_write_protect();
375 /* Opens the device. */
376 static int eeprom_open(struct inode
* inode
, struct file
* file
)
378 if(iminor(inode
) != EEPROM_MINOR_NR
)
380 if(imajor(inode
) != EEPROM_MAJOR_NR
)
383 if( eeprom
.size
> 0 )
389 /* No EEprom found */
393 /* Changes the current file position. */
395 static loff_t
eeprom_lseek(struct file
* file
, loff_t offset
, int orig
)
398 * orig 0: position from begning of eeprom
399 * orig 1: relative from current position
400 * orig 2: position from last eeprom address
406 file
->f_pos
= offset
;
409 file
->f_pos
+= offset
;
412 file
->f_pos
= eeprom
.size
- offset
;
418 /* truncate position */
425 if (file
->f_pos
>= eeprom
.size
)
427 file
->f_pos
= eeprom
.size
- 1;
431 return ( file
->f_pos
);
434 /* Reads data from eeprom. */
436 static int eeprom_read_buf(loff_t addr
, char * buf
, int count
)
438 return eeprom_read(NULL
, buf
, count
, &addr
);
443 /* Reads data from eeprom. */
445 static ssize_t
eeprom_read(struct file
* file
, char * buf
, size_t count
, loff_t
*off
)
448 unsigned long p
= *off
;
452 if(p
>= eeprom
.size
) /* Address i 0 - (size-1) */
457 if (mutex_lock_interruptible(&eeprom
.lock
))
460 page
= (unsigned char) (p
>> 8);
462 if(!eeprom_address(p
))
464 printk(KERN_INFO
"%s: Read failed to address the eeprom: "
465 "0x%08X (%i) page: %i\n", eeprom_name
, (int)p
, (int)p
, page
);
468 /* don't forget to wake them up */
469 mutex_unlock(&eeprom
.lock
);
473 if( (p
+ count
) > eeprom
.size
)
476 count
= eeprom
.size
- p
;
479 /* stop dummy write op and initiate the read op */
482 /* special case for small eeproms */
483 if(eeprom
.size
< EEPROM_16KB
)
485 i2c_outbyte( eeprom
.select_cmd
| 1 | (page
<< 1) );
488 /* go on with the actual read */
489 read
= read_from_eeprom( buf
, count
);
496 mutex_unlock(&eeprom
.lock
);
500 /* Writes data to eeprom. */
502 static int eeprom_write_buf(loff_t addr
, const char * buf
, int count
)
504 return eeprom_write(NULL
, buf
, count
, &addr
);
508 /* Writes data to eeprom. */
510 static ssize_t
eeprom_write(struct file
* file
, const char * buf
, size_t count
,
513 int i
, written
, restart
=1;
516 if (!access_ok(VERIFY_READ
, buf
, count
))
521 /* bail out if we get interrupted */
522 if (mutex_lock_interruptible(&eeprom
.lock
))
524 for(i
= 0; (i
< EEPROM_RETRIES
) && (restart
> 0); i
++)
531 while( (written
< count
) && (p
< eeprom
.size
))
533 /* address the eeprom */
534 if(!eeprom_address(p
))
536 printk(KERN_INFO
"%s: Write failed to address the eeprom: "
537 "0x%08X (%i) \n", eeprom_name
, (int)p
, (int)p
);
540 /* don't forget to wake them up */
541 mutex_unlock(&eeprom
.lock
);
544 #ifdef EEPROM_ADAPTIVE_TIMING
545 /* Adaptive algorithm to adjust timing */
546 if (eeprom
.retry_cnt_addr
> 0)
549 D(printk(">D=%i d=%i\n",
550 eeprom
.usec_delay_writecycles
, eeprom
.usec_delay_step
));
552 if (eeprom
.usec_delay_step
< 4)
554 eeprom
.usec_delay_step
++;
555 eeprom
.usec_delay_writecycles
+= eeprom
.usec_delay_step
;
560 if (eeprom
.adapt_state
> 0)
563 eeprom
.usec_delay_step
*= 2;
564 if (eeprom
.usec_delay_step
> 2)
566 eeprom
.usec_delay_step
--;
568 eeprom
.usec_delay_writecycles
+= eeprom
.usec_delay_step
;
570 else if (eeprom
.adapt_state
< 0)
572 /* To High before (toggle dir) */
573 eeprom
.usec_delay_writecycles
+= eeprom
.usec_delay_step
;
574 if (eeprom
.usec_delay_step
> 1)
576 eeprom
.usec_delay_step
/= 2;
577 eeprom
.usec_delay_step
--;
582 eeprom
.adapt_state
= 1;
586 /* To High (or good) now */
587 D(printk("<D=%i d=%i\n",
588 eeprom
.usec_delay_writecycles
, eeprom
.usec_delay_step
));
590 if (eeprom
.adapt_state
< 0)
593 if (eeprom
.usec_delay_step
> 1)
595 eeprom
.usec_delay_step
*= 2;
596 eeprom
.usec_delay_step
--;
598 if (eeprom
.usec_delay_writecycles
> eeprom
.usec_delay_step
)
600 eeprom
.usec_delay_writecycles
-= eeprom
.usec_delay_step
;
604 else if (eeprom
.adapt_state
> 0)
606 /* To Low before (toggle dir) */
607 if (eeprom
.usec_delay_writecycles
> eeprom
.usec_delay_step
)
609 eeprom
.usec_delay_writecycles
-= eeprom
.usec_delay_step
;
611 if (eeprom
.usec_delay_step
> 1)
613 eeprom
.usec_delay_step
/= 2;
614 eeprom
.usec_delay_step
--;
617 eeprom
.adapt_state
= -1;
620 if (eeprom
.adapt_state
> -100)
622 eeprom
.adapt_state
--;
626 /* Restart adaption */
627 D(printk("#Restart\n"));
628 eeprom
.usec_delay_step
++;
631 #endif /* EEPROM_ADAPTIVE_TIMING */
632 /* write until we hit a page boundary or count */
635 i2c_outbyte(buf
[written
]);
639 printk(KERN_INFO
"%s: write error, retrying. %d\n", eeprom_name
, i
);
645 } while( written
< count
&& ( p
% eeprom
.sequential_write_pagesize
));
647 /* end write cycle */
649 i2c_delay(eeprom
.usec_delay_writecycles
);
653 mutex_unlock(&eeprom
.lock
);
654 if (written
== 0 && p
>= eeprom
.size
){
661 /* Closes the device. */
663 static int eeprom_close(struct inode
* inode
, struct file
* file
)
665 /* do nothing for now */
669 /* Sets the current address of the eeprom. */
671 static int eeprom_address(unsigned long addr
)
674 unsigned char page
, offset
;
676 page
= (unsigned char) (addr
>> 8);
677 offset
= (unsigned char) addr
;
679 for(i
= 0; i
< EEPROM_RETRIES
; i
++)
681 /* start a dummy write for addressing */
684 if(eeprom
.size
== EEPROM_16KB
)
686 i2c_outbyte( eeprom
.select_cmd
);
692 i2c_outbyte( eeprom
.select_cmd
| (page
<< 1) );
698 /* Must have a delay here.. 500 works, >50, 100->works 5th time*/
699 i2c_delay(MAX_WRITEDELAY_US
/ EEPROM_RETRIES
* i
);
700 /* The chip needs up to 10 ms from write stop to next start */
718 eeprom
.retry_cnt_addr
= i
;
719 D(printk("%i\n", eeprom
.retry_cnt_addr
));
720 if(eeprom
.retry_cnt_addr
== EEPROM_RETRIES
)
728 /* Reads from current address. */
730 static int read_from_eeprom(char * buf
, int count
)
734 for(i
= 0; i
< EEPROM_RETRIES
; i
++)
736 if(eeprom
.size
== EEPROM_16KB
)
738 i2c_outbyte( eeprom
.select_cmd
| 1 );
747 if(i
== EEPROM_RETRIES
)
749 printk(KERN_INFO
"%s: failed to read from eeprom\n", eeprom_name
);
755 while( (read
< count
))
757 if (put_user(i2c_inbyte(), &buf
[read
++]))
765 * make sure we don't ack last byte or you will get very strange
774 /* stop the operation */
780 /* Disables write protection if applicable. */
783 #define ax_printf printk
784 static void eeprom_disable_write_protect(void)
786 /* Disable write protect */
787 if (eeprom
.size
== EEPROM_8KB
)
789 /* Step 1 Set WEL = 1 (write 00000010 to address 1FFFh */
794 DBP_SAVE(ax_printf("Get ack returns false\n"));
799 DBP_SAVE(ax_printf("Get ack returns false 2\n"));
804 DBP_SAVE(ax_printf("Get ack returns false 3\n"));
810 /* Step 2 Set RWEL = 1 (write 00000110 to address 1FFFh */
815 DBP_SAVE(ax_printf("Get ack returns false 55\n"));
820 DBP_SAVE(ax_printf("Get ack returns false 52\n"));
825 DBP_SAVE(ax_printf("Get ack returns false 53\n"));
829 /* Step 3 Set BP1, BP0, and/or WPEN bits (write 00000110 to address 1FFFh */
834 DBP_SAVE(ax_printf("Get ack returns false 56\n"));
839 DBP_SAVE(ax_printf("Get ack returns false 57\n"));
844 DBP_SAVE(ax_printf("Get ack returns false 58\n"));
848 /* Write protect disabled */
852 module_init(eeprom_init
);