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