| // SPDX-License-Identifier: GPL-2.0 |
| /*!***************************************************************************** |
| *! |
| *! 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. |
| *! |
| *! (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 <linux/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 */ |
| struct mutex lock; |
| 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) |
| { |
| mutex_init(&eeprom.lock); |
| |
| #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 beginning 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) |
| { |
| return eeprom_read(NULL, 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 = *off; |
| |
| unsigned char page; |
| |
| if(p >= eeprom.size) /* Address i 0 - (size-1) */ |
| { |
| return -EFAULT; |
| } |
| |
| if (mutex_lock_interruptible(&eeprom.lock)) |
| return -EINTR; |
| |
| 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 */ |
| mutex_unlock(&eeprom.lock); |
| 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) |
| { |
| *off += read; |
| } |
| |
| mutex_unlock(&eeprom.lock); |
| return read; |
| } |
| |
| /* Writes data to eeprom. */ |
| |
| static int eeprom_write_buf(loff_t addr, const char * buf, int count) |
| { |
| return eeprom_write(NULL, 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; |
| } |
| |
| /* bail out if we get interrupted */ |
| if (mutex_lock_interruptible(&eeprom.lock)) |
| return -EINTR; |
| for(i = 0; (i < EEPROM_RETRIES) && (restart > 0); i++) |
| { |
| restart = 0; |
| written = 0; |
| p = *off; |
| |
| |
| 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 */ |
| mutex_unlock(&eeprom.lock); |
| 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 */ |
| |
| mutex_unlock(&eeprom.lock); |
| if (written == 0 && p >= eeprom.size){ |
| return -ENOSPC; |
| } |
| *off = p; |
| 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 */ |
| } |
| } |
| device_initcall(eeprom_init); |
