u-boot/board/gth/ee_access.c

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2002-08-17 09:36:01 +00:00
/* Module for handling DALLAS DS2438, smart battery monitor
Chip can store up to 40 bytes of user data in EEPROM,
perform temp, voltage and current measurements.
Chip also contains a unique serial number.
Always read/write LSb first
For documentaion, see data sheet for DS2438, 2438.pdf
By Thomas.Lange@corelatus.com 001025 */
#include <common.h>
#include <config.h>
#include <mpc8xx.h>
#include <../board/gth/ee_dev.h>
/* We dont have kernel functions */
#define printk printf
#define KERN_DEBUG
#define KERN_ERR
#define EIO 1
static int Debug = 0;
#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif
/*
* lookup table ripped from DS app note 17, understanding and using
* cyclic redundancy checks...
*/
static u8 crc_lookup[256] = {
0, 94, 188, 226, 97, 63, 221, 131,
194, 156, 126, 32, 163, 253, 31, 65,
157, 195, 33, 127, 252, 162, 64, 30,
95, 1, 227, 189, 62, 96, 130, 220,
35, 125, 159, 193, 66, 28, 254, 160,
225, 191, 93, 3, 128, 222, 60, 98,
190, 224, 2, 92, 223, 129, 99, 61,
124, 34, 192, 158, 29, 67, 161, 255,
70, 24, 250, 164, 39, 121, 155, 197,
132, 218, 56, 102, 229, 187, 89, 7,
219, 133, 103, 57, 186, 228, 6, 88,
25, 71, 165, 251, 120, 38, 196, 154,
101, 59, 217, 135, 4, 90, 184, 230,
167, 249, 27, 69, 198, 152, 122, 36,
248, 166, 68, 26, 153, 199, 37, 123,
58, 100, 134, 216, 91, 5, 231, 185,
140, 210, 48, 110, 237, 179, 81, 15,
78, 16, 242, 172, 47, 113, 147, 205,
17, 79, 173, 243, 112, 46, 204, 146,
211, 141, 111, 49, 178, 236, 14, 80,
175, 241, 19, 77, 206, 144, 114, 44,
109, 51, 209, 143, 12, 82, 176, 238,
50, 108, 142, 208, 83, 13, 239, 177,
240, 174, 76, 18, 145, 207, 45, 115,
202, 148, 118, 40, 171, 245, 23, 73,
8, 86, 180, 234, 105, 55, 213, 139,
87, 9, 235, 181, 54, 104, 138, 212,
149, 203, 41, 119, 244, 170, 72, 22,
233, 183, 85, 11, 136, 214, 52, 106,
43, 117, 151, 201, 74, 20, 246, 168,
116, 42, 200, 150, 21, 75, 169, 247,
182, 232, 10, 84, 215, 137, 107, 53
};
static u8 make_new_crc( u8 Old_crc, u8 New_value ){
/* Compute a new checksum with new byte, using previous checksum as input
See DS app note 17, understanding and using cyclic redundancy checks...
Also see DS2438, page 11 */
return( crc_lookup[Old_crc ^ New_value ]);
}
int ee_crc_ok( u8 *Buffer, int Len, u8 Crc ){
/* Check if the checksum for this buffer is correct */
u8 Curr_crc=0;
int i;
u8 *Curr_byte = Buffer;
for(i=0;i<Len;i++){
Curr_crc = make_new_crc( Curr_crc, *Curr_byte);
Curr_byte++;
}
E_DEBUG("Calculated CRC = 0x%x, read = 0x%x\n", Curr_crc, Crc);
if(Curr_crc == Crc){
/* Good */
return(TRUE);
}
printk(KERN_ERR"EE checksum error, Calculated CRC = 0x%x, read = 0x%x\n",
Curr_crc, Crc);
return(FALSE);
}
static void
set_idle(void){
/* Send idle and keep start time
Continous 1 is idle */
WRITE_PORT(1);
}
static int
do_reset(void){
/* Release reset and verify that chip responds with presence pulse */
int Retries = 0;
while(Retries<5){
udelay(RESET_LOW_TIME);
/* Send reset */
WRITE_PORT(0);
udelay(RESET_LOW_TIME);
/* Release reset */
WRITE_PORT(1);
/* Wait for EEPROM to drive output */
udelay(PRESENCE_TIMEOUT);
if(!READ_PORT){
/* Ok, EEPROM is driving a 0 */
E_DEBUG("Presence detected\n");
if(Retries){
E_DEBUG("Retries %d\n",Retries);
}
/* Make sure chip releases pin */
udelay(PRESENCE_LOW_TIME);
return 0;
}
Retries++;
}
printk(KERN_ERR"EEPROM did not respond when releasing reset\n");
/* Make sure chip releases pin */
udelay(PRESENCE_LOW_TIME);
/* Set to idle again */
set_idle();
return(-EIO);
}
static u8
read_byte(void){
/* Read a single byte from EEPROM
Read LSb first */
int i;
int Value;
u8 Result=0;
#ifndef CONFIG_SYS_IMMR
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u32 Flags;
#endif
E_DEBUG("Reading byte\n");
for(i=0;i<8;i++){
/* Small delay between pulses */
udelay(1);
#ifndef CONFIG_SYS_IMMR
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/* Disable irq */
save_flags(Flags);
cli();
#endif
/* Pull down pin short time to start read
See page 26 in data sheet */
WRITE_PORT(0);
udelay(READ_LOW);
WRITE_PORT(1);
/* Wait for chip to drive pin */
udelay(READ_TIMEOUT);
Value = READ_PORT;
if(Value)
Value=1;
#ifndef CONFIG_SYS_IMMR
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/* Enable irq */
restore_flags(Flags);
#endif
/* Wait for chip to release pin */
udelay(TOTAL_READ_LOW-READ_TIMEOUT);
/* LSb first */
Result|=Value<<i;
}
E_DEBUG("Read byte 0x%x\n",Result);
return(Result);
}
static void
write_byte(u8 Byte){
/* Write a single byte to EEPROM
Write LSb first */
int i;
int Value;
#ifndef CONFIG_SYS_IMMR
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u32 Flags;
#endif
E_DEBUG("Writing byte 0x%x\n",Byte);
for(i=0;i<8;i++){
/* Small delay between pulses */
udelay(1);
Value = Byte&1;
#ifndef CONFIG_SYS_IMMR
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/* Disable irq */
save_flags(Flags);
cli();
#endif
/* Pull down pin short time for a 1, long time for a 0
See page 26 in data sheet */
WRITE_PORT(0);
if(Value){
/* Write a 1 */
udelay(WRITE_1_LOW);
}
else{
/* Write a 0 */
udelay(WRITE_0_LOW);
}
WRITE_PORT(1);
#ifndef CONFIG_SYS_IMMR
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/* Enable irq */
restore_flags(Flags);
#endif
if(Value)
/* Wait for chip to read the 1 */
udelay(TOTAL_WRITE_LOW-WRITE_1_LOW);
Byte>>=1;
}
}
int ee_do_command( u8 *Tx, int Tx_len, u8 *Rx, int Rx_len, int Send_skip ){
/* Execute this command string, including
giving reset and setting to idle after command
if Rx_len is set, we read out data from EEPROM */
int i;
E_DEBUG("Command, Tx_len %d, Rx_len %d\n", Tx_len, Rx_len );
if(do_reset()){
/* Failed! */
return(-EIO);
}
if(Send_skip)
/* Always send SKIP_ROM first to tell chip we are sending a command,
except when we read out rom data for chip */
write_byte(SKIP_ROM);
/* Always have Tx data */
for(i=0;i<Tx_len;i++){
write_byte(Tx[i]);
}
if(Rx_len){
for(i=0;i<Rx_len;i++){
Rx[i]=read_byte();
}
}
set_idle();
E_DEBUG("Command done\n");
return(0);
}
int ee_init_data(void){
int i;
u8 Tx[10];
int tmp;
volatile immap_t *immap = (immap_t *)CONFIG_SYS_IMMR;
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while(0){
tmp = 1-tmp;
if(tmp)
immap->im_ioport.iop_padat &= ~PA_FRONT_LED;
else
immap->im_ioport.iop_padat |= PA_FRONT_LED;
udelay(1);
}
/* Set port to open drain to be able to read data from
port without setting it to input */
PORT_B_PAR &= ~PB_EEPROM;
PORT_B_ODR |= PB_EEPROM;
SET_PORT_B_OUTPUT(PB_EEPROM);
/* Set idle mode */
set_idle();
/* Copy all User EEPROM data to scratchpad */
for(i=0;i<USER_PAGES;i++){
Tx[0]=RECALL_MEMORY;
Tx[1]=EE_USER_PAGE_0+i;
if(ee_do_command(Tx,2,NULL,0,TRUE)) return(-EIO);
}
/* Make sure chip doesnt store measurements in NVRAM */
Tx[0]=WRITE_SCRATCHPAD;
Tx[1]=0; /* Page */
Tx[2]=9;
if(ee_do_command(Tx,3,NULL,0,TRUE)) return(-EIO);
Tx[0]=COPY_SCRATCHPAD;
if(ee_do_command(Tx,2,NULL,0,TRUE)) return(-EIO);
/* FIXME check status bit instead
Could take 10 ms to store in EEPROM */
for(i=0;i<10;i++){
udelay(1000);
}
return(0);
}