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 */ 55 static inline void eeprom_cmd(volatile unsigned int *ctrl, unsigned cmd, 56 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 *ctrl |= EEPROM_DATO; 65 else 66 *ctrl &= ~EEPROM_DATO; 67 *ctrl &= ~EEPROM_ECLK; 68 *ctrl |= EEPROM_ECLK; 69 ser_cmd <<= 1; 70 } 71 *ctrl &= ~EEPROM_DATO; /* see data sheet timing diagram */ 72 } 73 74 unsigned short ip22_eeprom_read(volatile unsigned int *ctrl, int reg) 75 { 76 unsigned short res = 0; 77 int i; 78 79 *ctrl &= ~EEPROM_EPROT; 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 *ctrl &= ~EEPROM_ECLK; 86 delay(); 87 *ctrl |= EEPROM_ECLK; 88 delay(); 89 res <<= 1; 90 if (*ctrl & EEPROM_DATI) 91 res |= 1; 92 } 93 94 eeprom_cs_off(ctrl); 95 96 return res; 97 } 98 99 EXPORT_SYMBOL(ip22_eeprom_read); 100 101 /* 102 * Read specified register from main NVRAM 103 */ 104 unsigned 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 } 118 119 EXPORT_SYMBOL(ip22_nvram_read); 120