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