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/export.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 __raw_writel(__raw_readl(ptr) & ~EEPROM_DATO, ptr); \ 36 __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr); \ 37 __raw_writel(__raw_readl(ptr) & ~EEPROM_EPROT, ptr); \ 38 delay(); \ 39 __raw_writel(__raw_readl(ptr) | EEPROM_CSEL, ptr); \ 40 __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); }) 41 42 43 #define eeprom_cs_off(ptr) ({ \ 44 __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr); \ 45 __raw_writel(__raw_readl(ptr) & ~EEPROM_CSEL, ptr); \ 46 __raw_writel(__raw_readl(ptr) | EEPROM_EPROT, ptr); \ 47 __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); }) 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(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 __raw_writel(__raw_readl(ctrl) | EEPROM_DATO, ctrl); 64 else 65 __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl); 66 __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl); 67 delay(); 68 __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl); 69 delay(); 70 ser_cmd <<= 1; 71 } 72 /* see data sheet timing diagram */ 73 __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl); 74 } 75 76 unsigned short ip22_eeprom_read(unsigned int *ctrl, int reg) 77 { 78 unsigned short res = 0; 79 int i; 80 81 __raw_writel(__raw_readl(ctrl) & ~EEPROM_EPROT, ctrl); 82 eeprom_cs_on(ctrl); 83 eeprom_cmd(ctrl, EEPROM_READ, reg); 84 85 /* clock the data ouf of serial mem */ 86 for (i = 0; i < 16; i++) { 87 __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl); 88 delay(); 89 __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl); 90 delay(); 91 res <<= 1; 92 if (__raw_readl(ctrl) & EEPROM_DATI) 93 res |= 1; 94 } 95 96 eeprom_cs_off(ctrl); 97 98 return res; 99 } 100 101 EXPORT_SYMBOL(ip22_eeprom_read); 102 103 /* 104 * Read specified register from main NVRAM 105 */ 106 unsigned short ip22_nvram_read(int reg) 107 { 108 if (ip22_is_fullhouse()) 109 /* IP22 (Indigo2 aka FullHouse) stores env variables into 110 * 93CS56 Microwire Bus EEPROM 2048 Bit (128x16) */ 111 return ip22_eeprom_read(&hpc3c0->eeprom, reg); 112 else { 113 unsigned short tmp; 114 /* IP24 (Indy aka Guiness) uses DS1386 8K version */ 115 reg <<= 1; 116 tmp = hpc3c0->bbram[reg++] & 0xff; 117 return (tmp << 8) | (hpc3c0->bbram[reg] & 0xff); 118 } 119 } 120 121 EXPORT_SYMBOL(ip22_nvram_read); 122