LXR linux/arch/mips/sgi-ip22/ip22-nvram.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * ip22-nvram.c: NVRAM and serial EEPROM handling.
   4 *
   5 * Copyright (C) 2003 Ladislav Michl (ladis@linux-mips.org)
   6 */
   7#include <linux/export.h>
   8
   9#include <asm/sgi/hpc3.h>
  10#include <asm/sgi/ip22.h>
  11
  12/* Control opcode for serial eeprom  */
  13#define EEPROM_READ     0xc000  /* serial memory read */
  14#define EEPROM_WEN      0x9800  /* write enable before prog modes */
  15#define EEPROM_WRITE    0xa000  /* serial memory write */
  16#define EEPROM_WRALL    0x8800  /* write all registers */
  17#define EEPROM_WDS      0x8000  /* disable all programming */
  18#define EEPROM_PRREAD   0xc000  /* read protect register */
  19#define EEPROM_PREN     0x9800  /* enable protect register mode */
  20#define EEPROM_PRCLEAR  0xffff  /* clear protect register */
  21#define EEPROM_PRWRITE  0xa000  /* write protect register */
  22#define EEPROM_PRDS     0x8000  /* disable protect register, forever */
  23
  24#define EEPROM_EPROT    0x01    /* Protect register enable */
  25#define EEPROM_CSEL     0x02    /* Chip select */
  26#define EEPROM_ECLK     0x04    /* EEPROM clock */
  27#define EEPROM_DATO     0x08    /* Data out */
  28#define EEPROM_DATI     0x10    /* Data in */
  29
  30/* We need to use these functions early... */
  31#define delay() ({                                              \
  32        int x;                                                  \
  33        for (x=0; x<100000; x++) __asm__ __volatile__(""); })
  34
  35#define eeprom_cs_on(ptr) ({    \
  36        __raw_writel(__raw_readl(ptr) & ~EEPROM_DATO, ptr);     \
  37        __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);     \
  38        __raw_writel(__raw_readl(ptr) & ~EEPROM_EPROT, ptr);    \
  39        delay();                                                \
  40        __raw_writel(__raw_readl(ptr) | EEPROM_CSEL, ptr);      \
  41        __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
  42
  43
  44#define eeprom_cs_off(ptr) ({   \
  45        __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);     \
  46        __raw_writel(__raw_readl(ptr) & ~EEPROM_CSEL, ptr);     \
  47        __raw_writel(__raw_readl(ptr) | EEPROM_EPROT, ptr);     \
  48        __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
  49
  50#define BITS_IN_COMMAND 11
  51/*
  52 * clock in the nvram command and the register number. For the
  53 * national semiconductor nv ram chip the op code is 3 bits and
  54 * the address is 6/8 bits.
  55 */
  56static inline void eeprom_cmd(unsigned int *ctrl, unsigned cmd, unsigned reg)
  57{
  58        unsigned short ser_cmd;
  59        int i;
  60
  61        ser_cmd = cmd | (reg << (16 - BITS_IN_COMMAND));
  62        for (i = 0; i < BITS_IN_COMMAND; i++) {
  63                if (ser_cmd & (1<<15))  /* if high order bit set */
  64                        __raw_writel(__raw_readl(ctrl) | EEPROM_DATO, ctrl);
  65                else
  66                        __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
  67                __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
  68                delay();
  69                __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
  70                delay();
  71                ser_cmd <<= 1;
  72        }
  73        /* see data sheet timing diagram */
  74        __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
  75}
  76
  77unsigned short ip22_eeprom_read(unsigned int *ctrl, int reg)
  78{
  79        unsigned short res = 0;
  80        int i;
  81
  82        __raw_writel(__raw_readl(ctrl) & ~EEPROM_EPROT, ctrl);
  83        eeprom_cs_on(ctrl);
  84        eeprom_cmd(ctrl, EEPROM_READ, reg);
  85
  86        /* clock the data ouf of serial mem */
  87        for (i = 0; i < 16; i++) {
  88                __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
  89                delay();
  90                __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
  91                delay();
  92                res <<= 1;
  93                if (__raw_readl(ctrl) & EEPROM_DATI)
  94                        res |= 1;
  95        }
  96
  97        eeprom_cs_off(ctrl);
  98
  99        return res;
 100}
 101
 102EXPORT_SYMBOL(ip22_eeprom_read);
 103
 104/*
 105 * Read specified register from main NVRAM
 106 */
 107unsigned short ip22_nvram_read(int reg)
 108{
 109        if (ip22_is_fullhouse())
 110                /* IP22 (Indigo2 aka FullHouse) stores env variables into
 111                 * 93CS56 Microwire Bus EEPROM 2048 Bit (128x16) */
 112                return ip22_eeprom_read(&hpc3c0->eeprom, reg);
 113        else {
 114                unsigned short tmp;
 115                /* IP24 (Indy aka Guiness) uses DS1386 8K version */
 116                reg <<= 1;
 117                tmp = hpc3c0->bbram[reg++] & 0xff;
 118                return (tmp << 8) | (hpc3c0->bbram[reg] & 0xff);
 119        }
 120}
 121
 122EXPORT_SYMBOL(ip22_nvram_read);
 123