ip22-nvram.c

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/*
 * ip22-nvram.c: NVRAM and serial EEPROM handling.
 *
 * Copyright (C) 2003 Ladislav Michl ([email protected])
 */
#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) ({    \
    __raw_writel(__raw_readl(ptr) & ~EEPROM_DATO, ptr); \
    __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr); \
    __raw_writel(__raw_readl(ptr) & ~EEPROM_EPROT, ptr);    \
    delay();                                        \
    __raw_writel(__raw_readl(ptr) | EEPROM_CSEL, ptr);  \
    __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })


#define eeprom_cs_off(ptr) ({   \
    __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr); \
    __raw_writel(__raw_readl(ptr) & ~EEPROM_CSEL, ptr); \
    __raw_writel(__raw_readl(ptr) | EEPROM_EPROT, ptr); \
    __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })

#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(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 */
            __raw_writel(__raw_readl(ctrl) | EEPROM_DATO, ctrl);
        else
            __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
        __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
        delay();
        __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
        delay();
        ser_cmd <<= 1;
    }
    /* see data sheet timing diagram */
    __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
}

unsigned short ip22_eeprom_read(unsigned int *ctrl, int reg)
{
    unsigned short res = 0;
    int i;

    __raw_writel(__raw_readl(ctrl) & ~EEPROM_EPROT, ctrl);
    eeprom_cs_on(ctrl);
    eeprom_cmd(ctrl, EEPROM_READ, reg);

    /* clock the data ouf of serial mem */
    for (i = 0; i < 16; i++) {
        __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
        delay();
        __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
        delay();
        res <<= 1;
        if (__raw_readl(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);