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