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(ctrl: &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 | |