Initial revision

1 files changed, 335 insertions, 0 deletions

diff --git a/board/gth/ee_access.c b/board/gth/ee_access.c
new file mode 100644
index 0000000..716c90e
--- /dev/null
+++ b/board/gth/ee_access.c
@@ -0,0 +1,335 @@
+/* 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 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 void
+write_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);
+}