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/*
* ip22-nvram.c: NVRAM and serial EEPROM handling.
*
* Copyright (C) 2003 Ladislav Michl (ladis@linux-mips.org)
*/
#include <linux/module.h>
#include <asm/sgi/hpc3.h>
#include <asm/sgi/ip22.h>
/* Control opcode for serial eeprom */
#define EEPROM_READ 0xc000 /* serial memory read */
#define EEPROM_WEN 0x9800 /* write enable before prog modes */
#define EEPROM_WRITE 0xa000 /* serial memory write */
#define EEPROM_WRALL 0x8800 /* write all registers */
#define EEPROM_WDS 0x8000 /* disable all programming */
#define EEPROM_PRREAD 0xc000 /* read protect register */
#define EEPROM_PREN 0x9800 /* enable protect register mode */
#define EEPROM_PRCLEAR 0xffff /* clear protect register */
#define EEPROM_PRWRITE 0xa000 /* write protect register */
#define EEPROM_PRDS 0x8000 /* disable protect register, forever */
#define EEPROM_EPROT 0x01 /* Protect register enable */
#define EEPROM_CSEL 0x02 /* Chip select */
#define EEPROM_ECLK 0x04 /* EEPROM clock */
#define EEPROM_DATO 0x08 /* Data out */
#define EEPROM_DATI 0x10 /* Data in */
/* We need to use these functions early... */
#define delay() ({ \
int x; \
for (x=0; x<100000; x++) __asm__ __volatile__(""); })
#define eeprom_cs_on(ptr) ({ \
*ptr &= ~EEPROM_DATO; \
*ptr &= ~EEPROM_ECLK; \
*ptr &= ~EEPROM_EPROT; \
delay(); \
*ptr |= EEPROM_CSEL; \
*ptr |= EEPROM_ECLK; })
#define eeprom_cs_off(ptr) ({ \
*ptr &= ~EEPROM_ECLK; \
*ptr &= ~EEPROM_CSEL; \
*ptr |= EEPROM_EPROT; \
*ptr |= EEPROM_ECLK; })
#define BITS_IN_COMMAND 11
/*
* clock in the nvram command and the register number. For the
* national semiconductor nv ram chip the op code is 3 bits and
* the address is 6/8 bits.
*/
static inline void eeprom_cmd(volatile unsigned int *ctrl, unsigned cmd,
unsigned reg)
{
unsigned short ser_cmd;
int i;
ser_cmd = cmd | (reg << (16 - BITS_IN_COMMAND));
for (i = 0; i < BITS_IN_COMMAND; i++) {
if (ser_cmd & (1<<15)) /* if high order bit set */
*ctrl |= EEPROM_DATO;
else
*ctrl &= ~EEPROM_DATO;
*ctrl &= ~EEPROM_ECLK;
*ctrl |= EEPROM_ECLK;
ser_cmd <<= 1;
}
*ctrl &= ~EEPROM_DATO; /* see data sheet timing diagram */
}
unsigned short ip22_eeprom_read(volatile unsigned int *ctrl, int reg)
{
unsigned short res = 0;
int i;
*ctrl &= ~EEPROM_EPROT;
eeprom_cs_on(ctrl);
eeprom_cmd(ctrl, EEPROM_READ, reg);
/* clock the data ouf of serial mem */
for (i = 0; i < 16; i++) {
*ctrl &= ~EEPROM_ECLK;
delay();
*ctrl |= EEPROM_ECLK;
delay();
res <<= 1;
if (*ctrl & EEPROM_DATI)
res |= 1;
}
eeprom_cs_off(ctrl);
return res;
}
EXPORT_SYMBOL(ip22_eeprom_read);
/*
* Read specified register from main NVRAM
*/
unsigned short ip22_nvram_read(int reg)
{
if (ip22_is_fullhouse())
/* IP22 (Indigo2 aka FullHouse) stores env variables into
* 93CS56 Microwire Bus EEPROM 2048 Bit (128x16) */
return ip22_eeprom_read(&hpc3c0->eeprom, reg);
else {
unsigned short tmp;
/* IP24 (Indy aka Guiness) uses DS1386 8K version */
reg <<= 1;
tmp = hpc3c0->bbram[reg++] & 0xff;
return (tmp << 8) | (hpc3c0->bbram[reg] & 0xff);
}
}
EXPORT_SYMBOL(ip22_nvram_read);
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