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1da177e4 LT |
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 | ||
42a3b4f2 | 42 | |
1da177e4 LT |
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 | |
42a3b4f2 | 53 | * the address is 6/8 bits. |
1da177e4 LT |
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 | } | |
42a3b4f2 | 93 | |
1da177e4 LT |
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); | |
42a3b4f2 | 116 | } |
1da177e4 LT |
117 | } |
118 | ||
119 | EXPORT_SYMBOL(ip22_nvram_read); |