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 */ 56 static 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 77 unsigned 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 } 101 102 EXPORT_SYMBOL(ip22_eeprom_read); 103 104 /* 105 * Read specified register from main NVRAM 106 */ 107 unsigned 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 } 121 122 EXPORT_SYMBOL(ip22_nvram_read); 123