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 */
75 wait_queue_head_t wait_q;
77 int retry_cnt_addr; /* Used to keep track of number of retries for
78 adaptive timing adjustments */
82 static int eeprom_open(struct inode * inode, struct file * file);
83 static loff_t eeprom_lseek(struct file * file, loff_t offset, int orig);
84 static ssize_t eeprom_read(struct file * file, char * buf, size_t count,
86 static ssize_t eeprom_write(struct file * file, const char * buf, size_t count,
88 static int eeprom_close(struct inode * inode, struct file * file);
90 static int eeprom_address(unsigned long addr);
91 static int read_from_eeprom(char * buf, int count);
92 static int eeprom_write_buf(loff_t addr, const char * buf, int count);
93 static int eeprom_read_buf(loff_t addr, char * buf, int count);
95 static void eeprom_disable_write_protect(void);
98 static const char eeprom_name[] = "eeprom";
100 /* chip description */
101 static struct eeprom_type eeprom;
103 /* This is the exported file-operations structure for this device. */
104 const struct file_operations eeprom_fops =
106 .llseek = eeprom_lseek,
108 .write = eeprom_write,
110 .release = eeprom_close
113 /* eeprom init call. Probes for different eeprom models. */
115 int __init eeprom_init(void)
117 init_waitqueue_head(&eeprom.wait_q);
120 #ifdef CONFIG_ETRAX_I2C_EEPROM_PROBE
121 #define EETEXT "Found"
123 #define EETEXT "Assuming"
125 if (register_chrdev(EEPROM_MAJOR_NR, eeprom_name, &eeprom_fops))
127 printk(KERN_INFO "%s: unable to get major %d for eeprom device\n",
128 eeprom_name, EEPROM_MAJOR_NR);
132 printk("EEPROM char device v0.3, (c) 2000 Axis Communications AB\n");
135 * Note: Most of this probing method was taken from the printserver (5470e)
136 * codebase. It did not contain a way of finding the 16kB chips
137 * (M24128 or variants). The method used here might not work
138 * for all models. If you encounter problems the easiest way
139 * is probably to define your model within #ifdef's, and hard-
144 eeprom.usec_delay_writecycles = INITIAL_WRITEDELAY_US;
145 eeprom.usec_delay_step = 128;
146 eeprom.adapt_state = 0;
148 #ifdef CONFIG_ETRAX_I2C_EEPROM_PROBE
155 unsigned char buf_2k_start[16];
157 /* Im not sure this will work... :) */
158 /* assume 2kB, if failure go for 16kB */
159 /* Test with 16kB settings.. */
160 /* If it's a 2kB EEPROM and we address it outside it's range
161 * it will mirror the address space:
162 * 1. We read two locations (that are mirrored),
163 * if the content differs * it's a 16kB EEPROM.
164 * 2. if it doesn't differ - write different value to one of the locations,
165 * check the other - if content still is the same it's a 2k EEPROM,
166 * restore original data.
169 #define LOC2 (0x1fb) /*1fb, 3ed, 5df, 7d1 */
173 eeprom.size = EEPROM_2KB;
174 eeprom.select_cmd = 0xA0;
175 eeprom.sequential_write_pagesize = 16;
176 if( eeprom_read_buf( 0, buf_2k_start, 16 ) == 16 )
178 D(printk("2k start: '%16.16s'\n", buf_2k_start));
182 printk(KERN_INFO "%s: Failed to read in 2k mode!\n", eeprom_name);
186 eeprom.size = EEPROM_16KB;
187 eeprom.select_cmd = 0xA0;
188 eeprom.sequential_write_pagesize = 64;
191 unsigned char loc1[4], loc2[4], tmp[4];
192 if( eeprom_read_buf(LOC2, loc2, 4) == 4)
194 if( eeprom_read_buf(LOC1, loc1, 4) == 4)
196 D(printk("0 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n",
197 LOC1, loc1, LOC2, loc2));
199 if (memcmp(loc1, loc2, 4) != 0 )
202 printk(KERN_INFO "%s: 16k detected in step 1\n", eeprom_name);
203 eeprom.size = EEPROM_16KB;
209 /* Do step 2 check */
212 if (eeprom_write_buf(LOC1, loc1, 1) == 1)
214 /* If 2k EEPROM this write will actually write 10 bytes
217 D(printk("1 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n",
218 LOC1, loc1, LOC2, loc2));
219 if( eeprom_read_buf(LOC1, tmp, 4) == 4)
221 D(printk("2 loc1: (%i) '%4.4s' tmp '%4.4s'\n",
223 if (memcmp(loc1, tmp, 4) != 0 )
225 printk(KERN_INFO "%s: read and write differs! Not 16kB\n",
229 if (eeprom_write_buf(LOC1, loc1, 1) == 1)
235 printk(KERN_INFO "%s: Restore 2k failed during probe,"
236 " EEPROM might be corrupt!\n", eeprom_name);
240 /* Go to 2k mode and write original data */
241 eeprom.size = EEPROM_2KB;
242 eeprom.select_cmd = 0xA0;
243 eeprom.sequential_write_pagesize = 16;
244 if( eeprom_write_buf(0, buf_2k_start, 16) == 16)
249 printk(KERN_INFO "%s: Failed to write back 2k start!\n",
253 eeprom.size = EEPROM_2KB;
259 if( eeprom_read_buf(LOC2, loc2, 1) == 1)
261 D(printk("0 loc1: (%i) '%4.4s' loc2 (%i) '%4.4s'\n",
262 LOC1, loc1, LOC2, loc2));
263 if (memcmp(loc1, loc2, 4) == 0 )
265 /* Data the same, must be mirrored -> 2k */
267 printk(KERN_INFO "%s: 2k detected in step 2\n", eeprom_name);
269 if (eeprom_write_buf(LOC1, loc1, 1) == 1)
275 printk(KERN_INFO "%s: Restore 2k failed during probe,"
276 " EEPROM might be corrupt!\n", eeprom_name);
280 eeprom.size = EEPROM_2KB;
284 printk(KERN_INFO "%s: 16k detected in step 2\n",
287 /* Data differs, assume 16k */
289 if (eeprom_write_buf(LOC1, loc1, 1) == 1)
295 printk(KERN_INFO "%s: Restore 16k failed during probe,"
296 " EEPROM might be corrupt!\n", eeprom_name);
299 eeprom.size = EEPROM_16KB;
308 printk(KERN_INFO "%s: Probing failed!, using 2KB!\n", eeprom_name);
309 eeprom.size = EEPROM_2KB;
320 eeprom.size = EEPROM_2KB;
328 eeprom.size = EEPROM_2KB;
334 eeprom.size = EEPROM_8KB;
339 #elif defined(CONFIG_ETRAX_I2C_EEPROM_16KB)
340 eeprom.size = EEPROM_16KB;
341 #elif defined(CONFIG_ETRAX_I2C_EEPROM_8KB)
342 eeprom.size = EEPROM_8KB;
343 #elif defined(CONFIG_ETRAX_I2C_EEPROM_2KB)
344 eeprom.size = EEPROM_2KB;
350 printk("%s: " EETEXT " i2c compatible 2kB eeprom.\n", eeprom_name);
351 eeprom.sequential_write_pagesize = 16;
352 eeprom.select_cmd = 0xA0;
355 printk("%s: " EETEXT " i2c compatible 8kB eeprom.\n", eeprom_name);
356 eeprom.sequential_write_pagesize = 16;
357 eeprom.select_cmd = 0x80;
360 printk("%s: " EETEXT " i2c compatible 16kB eeprom.\n", eeprom_name);
361 eeprom.sequential_write_pagesize = 64;
362 eeprom.select_cmd = 0xA0;
366 printk("%s: Did not find a supported eeprom\n", eeprom_name);
372 eeprom_disable_write_protect();
377 /* Opens the device. */
378 /* BKL not needed: no global resources accessed */
379 static int eeprom_open(struct inode * inode, struct file * file)
382 if(iminor(inode) != EEPROM_MINOR_NR)
384 if(imajor(inode) != EEPROM_MAJOR_NR)
387 if( eeprom.size > 0 )
393 /* No EEprom found */
397 /* Changes the current file position. */
399 static loff_t eeprom_lseek(struct file * file, loff_t offset, int orig)
402 * orig 0: position from begning of eeprom
403 * orig 1: relative from current position
404 * orig 2: position from last eeprom address
410 file->f_pos = offset;
413 file->f_pos += offset;
416 file->f_pos = eeprom.size - offset;
422 /* truncate position */
429 if (file->f_pos >= eeprom.size)
431 file->f_pos = eeprom.size - 1;
435 return ( file->f_pos );
438 /* Reads data from eeprom. */
440 static int eeprom_read_buf(loff_t addr, char * buf, int count)
445 return eeprom_read(&f, buf, count, &addr);
450 /* Reads data from eeprom. */
452 static ssize_t eeprom_read(struct file * file, char * buf, size_t count, loff_t *off)
455 unsigned long p = file->f_pos;
459 if(p >= eeprom.size) /* Address i 0 - (size-1) */
464 wait_event_interruptible(eeprom.wait_q, !eeprom.busy);
465 if (signal_pending(current))
470 page = (unsigned char) (p >> 8);
472 if(!eeprom_address(p))
474 printk(KERN_INFO "%s: Read failed to address the eeprom: "
475 "0x%08X (%i) page: %i\n", eeprom_name, (int)p, (int)p, page);
478 /* don't forget to wake them up */
480 wake_up_interruptible(&eeprom.wait_q);
484 if( (p + count) > eeprom.size)
487 count = eeprom.size - p;
490 /* stop dummy write op and initiate the read op */
493 /* special case for small eeproms */
494 if(eeprom.size < EEPROM_16KB)
496 i2c_outbyte( eeprom.select_cmd | 1 | (page << 1) );
499 /* go on with the actual read */
500 read = read_from_eeprom( buf, count);
508 wake_up_interruptible(&eeprom.wait_q);
512 /* Writes data to eeprom. */
514 static int eeprom_write_buf(loff_t addr, const char * buf, int count)
520 return eeprom_write(&f, buf, count, &addr);
524 /* Writes data to eeprom. */
526 static ssize_t eeprom_write(struct file * file, const char * buf, size_t count,
529 int i, written, restart=1;
532 if (!access_ok(VERIFY_READ, buf, count))
537 wait_event_interruptible(eeprom.wait_q, !eeprom.busy);
538 /* bail out if we get interrupted */
539 if (signal_pending(current))
542 for(i = 0; (i < EEPROM_RETRIES) && (restart > 0); i++)
549 while( (written < count) && (p < eeprom.size))
551 /* address the eeprom */
552 if(!eeprom_address(p))
554 printk(KERN_INFO "%s: Write failed to address the eeprom: "
555 "0x%08X (%i) \n", eeprom_name, (int)p, (int)p);
558 /* don't forget to wake them up */
560 wake_up_interruptible(&eeprom.wait_q);
563 #ifdef EEPROM_ADAPTIVE_TIMING
564 /* Adaptive algorithm to adjust timing */
565 if (eeprom.retry_cnt_addr > 0)
568 D(printk(">D=%i d=%i\n",
569 eeprom.usec_delay_writecycles, eeprom.usec_delay_step));
571 if (eeprom.usec_delay_step < 4)
573 eeprom.usec_delay_step++;
574 eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
579 if (eeprom.adapt_state > 0)
582 eeprom.usec_delay_step *= 2;
583 if (eeprom.usec_delay_step > 2)
585 eeprom.usec_delay_step--;
587 eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
589 else if (eeprom.adapt_state < 0)
591 /* To High before (toggle dir) */
592 eeprom.usec_delay_writecycles += eeprom.usec_delay_step;
593 if (eeprom.usec_delay_step > 1)
595 eeprom.usec_delay_step /= 2;
596 eeprom.usec_delay_step--;
601 eeprom.adapt_state = 1;
605 /* To High (or good) now */
606 D(printk("<D=%i d=%i\n",
607 eeprom.usec_delay_writecycles, eeprom.usec_delay_step));
609 if (eeprom.adapt_state < 0)
612 if (eeprom.usec_delay_step > 1)
614 eeprom.usec_delay_step *= 2;
615 eeprom.usec_delay_step--;
617 if (eeprom.usec_delay_writecycles > eeprom.usec_delay_step)
619 eeprom.usec_delay_writecycles -= eeprom.usec_delay_step;
623 else if (eeprom.adapt_state > 0)
625 /* To Low before (toggle dir) */
626 if (eeprom.usec_delay_writecycles > eeprom.usec_delay_step)
628 eeprom.usec_delay_writecycles -= eeprom.usec_delay_step;
630 if (eeprom.usec_delay_step > 1)
632 eeprom.usec_delay_step /= 2;
633 eeprom.usec_delay_step--;
636 eeprom.adapt_state = -1;
639 if (eeprom.adapt_state > -100)
641 eeprom.adapt_state--;
645 /* Restart adaption */
646 D(printk("#Restart\n"));
647 eeprom.usec_delay_step++;
650 #endif /* EEPROM_ADAPTIVE_TIMING */
651 /* write until we hit a page boundary or count */
654 i2c_outbyte(buf[written]);
658 printk(KERN_INFO "%s: write error, retrying. %d\n", eeprom_name, i);
664 } while( written < count && ( p % eeprom.sequential_write_pagesize ));
666 /* end write cycle */
668 i2c_delay(eeprom.usec_delay_writecycles);
673 wake_up_interruptible(&eeprom.wait_q);
674 if (written == 0 && file->f_pos >= eeprom.size){
677 file->f_pos += written;
681 /* Closes the device. */
683 static int eeprom_close(struct inode * inode, struct file * file)
685 /* do nothing for now */
689 /* Sets the current address of the eeprom. */
691 static int eeprom_address(unsigned long addr)
694 unsigned char page, offset;
696 page = (unsigned char) (addr >> 8);
697 offset = (unsigned char) addr;
699 for(i = 0; i < EEPROM_RETRIES; i++)
701 /* start a dummy write for addressing */
704 if(eeprom.size == EEPROM_16KB)
706 i2c_outbyte( eeprom.select_cmd );
712 i2c_outbyte( eeprom.select_cmd | (page << 1) );
718 /* Must have a delay here.. 500 works, >50, 100->works 5th time*/
719 i2c_delay(MAX_WRITEDELAY_US / EEPROM_RETRIES * i);
720 /* The chip needs up to 10 ms from write stop to next start */
738 eeprom.retry_cnt_addr = i;
739 D(printk("%i\n", eeprom.retry_cnt_addr));
740 if(eeprom.retry_cnt_addr == EEPROM_RETRIES)
748 /* Reads from current address. */
750 static int read_from_eeprom(char * buf, int count)
754 for(i = 0; i < EEPROM_RETRIES; i++)
756 if(eeprom.size == EEPROM_16KB)
758 i2c_outbyte( eeprom.select_cmd | 1 );
767 if(i == EEPROM_RETRIES)
769 printk(KERN_INFO "%s: failed to read from eeprom\n", eeprom_name);
775 while( (read < count))
777 if (put_user(i2c_inbyte(), &buf[read++]))
785 * make sure we don't ack last byte or you will get very strange
794 /* stop the operation */
800 /* Disables write protection if applicable. */
803 #define ax_printf printk
804 static void eeprom_disable_write_protect(void)
806 /* Disable write protect */
807 if (eeprom.size == EEPROM_8KB)
809 /* Step 1 Set WEL = 1 (write 00000010 to address 1FFFh */
814 DBP_SAVE(ax_printf("Get ack returns false\n"));
819 DBP_SAVE(ax_printf("Get ack returns false 2\n"));
824 DBP_SAVE(ax_printf("Get ack returns false 3\n"));
830 /* Step 2 Set RWEL = 1 (write 00000110 to address 1FFFh */
835 DBP_SAVE(ax_printf("Get ack returns false 55\n"));
840 DBP_SAVE(ax_printf("Get ack returns false 52\n"));
845 DBP_SAVE(ax_printf("Get ack returns false 53\n"));
849 /* Step 3 Set BP1, BP0, and/or WPEN bits (write 00000110 to address 1FFFh */
854 DBP_SAVE(ax_printf("Get ack returns false 56\n"));
859 DBP_SAVE(ax_printf("Get ack returns false 57\n"));
864 DBP_SAVE(ax_printf("Get ack returns false 58\n"));
868 /* Write protect disabled */
872 module_init(eeprom_init);