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-rw-r--r--board/gth/ee_access.c335
1 files changed, 335 insertions, 0 deletions
diff --git a/board/gth/ee_access.c b/board/gth/ee_access.c
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+/* 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);
+}
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