/* 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 1static 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 voidset_idle(void){  /* Send idle and keep start time     Continous 1 is idle */  WRITE_PORT(1);}static intdo_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 u8read_byte(void){  /* Read a single byte from EEPROM     Read LSb first */  int i;  int Value;  u8 Result=0;#ifndef CFG_IMMR  u32 Flags;#endif  E_DEBUG("Reading byte\n");  for(i=0;i<8;i++){    /* Small delay between pulses */    udelay(1);#ifndef CFG_IMMR    /* 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 CFG_IMMR    /* 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 voidwrite_byte(u8 Byte){  /* Write a single byte to EEPROM     Write LSb first */  int i;  int Value;#ifndef CFG_IMMR  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 CFG_IMMR    /* 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 CFG_IMMR    /* 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 *)CFG_IMMR;  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);}