/* 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   Copyright (C) 2000-2005 Corelatus AB *//* This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, * MA 02111-1307 USA */#include <common.h>#include <command.h>#include <asm/au1x00.h>#include <asm/io.h>#include "ee_dev.h"#include "ee_access.h"/* static int Debug = 1; */#undef E_DEBUG#define E_DEBUG(fmt,args...) /* *//* #define E_DEBUG(fmt,args...) printk("EEA:"fmt,##args); *//* We dont have kernel functions */#define printk printf#define KERN_DEBUG#define KERN_ERR#define EIO 1#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 voidwrite_gpio_data(int value ){	if(value){		/* Tristate */		gpio_tristate(GPIO_EEDQ);	}	else{		/* Drive 0 */		gpio_clear(GPIO_EEDQ);	}}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_cpu_reset(void){	/* Release reset and verify that chip responds with presence pulse */	int Retries=0;	while(Retries<15){		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_cpu_byte(void){	/* Read a single byte from EEPROM	   Read LSb first */	int i;	int Value;	u8 Result=0;	u32 Flags;	E_DEBUG("Reading byte\n");	for(i=0;i<8;i++){		/* Small delay between pulses */		udelay(1);#ifdef __KERNEL__		/* 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;#ifdef __KERNEL__		/* 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 %d\n",Value); */	}	E_DEBUG("Read byte 0x%x\n",Result);	return(Result);}static voidwrite_cpu_byte(u8 Byte){	/* Write a single byte to EEPROM	   Write LSb first */	int i;	int Value;	u32 Flags;	E_DEBUG("Writing byte 0x%x\n",Byte);	for(i=0;i<8;i++){		/* Small delay between pulses */		udelay(1);		Value = Byte&1;#ifdef __KERNEL__		/* 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);#ifdef __KERNEL__		/* Enable irq */		restore_flags(Flags);#endif		if(Value)			/* Wait for chip to read the 1 */			udelay(TOTAL_WRITE_LOW-WRITE_1_LOW);		/* E_DEBUG("Wrote %d\n",Value); */		Byte>>=1;	}}int ee_do_cpu_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_cpu_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_cpu_byte(SKIP_ROM);	/* Always have Tx data */	for(i=0;i<Tx_len;i++){		write_cpu_byte(Tx[i]);	}	if(Rx_len){		for(i=0;i<Rx_len;i++){			Rx[i]=read_cpu_byte();		}	}	set_idle();	E_DEBUG("Command done\n");	return(0);}int ee_init_cpu_data(void){	int i;	u8 Tx[10];	/* Leave it floting since altera is driving the same pin */	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_cpu_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_cpu_command(Tx,3,NULL,0,TRUE)) return(-EIO);	Tx[0]=COPY_SCRATCHPAD;	if(ee_do_cpu_command(Tx,2,NULL,0,TRUE)) return(-EIO);	for(i=0;i<10;i++){		udelay(1000);	}	return(0);}