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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Implement 'Simple Boot Flag Specification 2.0' | |
3 | */ | |
1da177e4 LT |
4 | #include <linux/types.h> |
5 | #include <linux/kernel.h> | |
6 | #include <linux/init.h> | |
7 | #include <linux/string.h> | |
1da177e4 LT |
8 | #include <linux/spinlock.h> |
9 | #include <linux/acpi.h> | |
10 | #include <asm/io.h> | |
11 | ||
12 | #include <linux/mc146818rtc.h> | |
13 | ||
1da177e4 LT |
14 | #define SBF_RESERVED (0x78) |
15 | #define SBF_PNPOS (1<<0) | |
16 | #define SBF_BOOTING (1<<1) | |
17 | #define SBF_DIAG (1<<2) | |
18 | #define SBF_PARITY (1<<7) | |
19 | ||
1da177e4 LT |
20 | int sbf_port __initdata = -1; /* set via acpi_boot_init() */ |
21 | ||
1da177e4 LT |
22 | static int __init parity(u8 v) |
23 | { | |
24 | int x = 0; | |
25 | int i; | |
8eed9260 CG |
26 | |
27 | for (i = 0; i < 8; i++) { | |
28 | x ^= (v & 1); | |
29 | v >>= 1; | |
1da177e4 | 30 | } |
8eed9260 | 31 | |
1da177e4 LT |
32 | return x; |
33 | } | |
34 | ||
35 | static void __init sbf_write(u8 v) | |
36 | { | |
37 | unsigned long flags; | |
8eed9260 CG |
38 | |
39 | if (sbf_port != -1) { | |
1da177e4 | 40 | v &= ~SBF_PARITY; |
8eed9260 CG |
41 | if (!parity(v)) |
42 | v |= SBF_PARITY; | |
1da177e4 | 43 | |
8eed9260 CG |
44 | printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n", |
45 | sbf_port, v); | |
1da177e4 LT |
46 | |
47 | spin_lock_irqsave(&rtc_lock, flags); | |
48 | CMOS_WRITE(v, sbf_port); | |
49 | spin_unlock_irqrestore(&rtc_lock, flags); | |
50 | } | |
51 | } | |
52 | ||
53 | static u8 __init sbf_read(void) | |
54 | { | |
1da177e4 | 55 | unsigned long flags; |
8eed9260 CG |
56 | u8 v; |
57 | ||
58 | if (sbf_port == -1) | |
1da177e4 | 59 | return 0; |
8eed9260 | 60 | |
1da177e4 LT |
61 | spin_lock_irqsave(&rtc_lock, flags); |
62 | v = CMOS_READ(sbf_port); | |
63 | spin_unlock_irqrestore(&rtc_lock, flags); | |
8eed9260 | 64 | |
1da177e4 LT |
65 | return v; |
66 | } | |
67 | ||
68 | static int __init sbf_value_valid(u8 v) | |
69 | { | |
8eed9260 | 70 | if (v & SBF_RESERVED) /* Reserved bits */ |
1da177e4 | 71 | return 0; |
8eed9260 | 72 | if (!parity(v)) |
1da177e4 | 73 | return 0; |
8eed9260 | 74 | |
1da177e4 LT |
75 | return 1; |
76 | } | |
77 | ||
78 | static int __init sbf_init(void) | |
79 | { | |
80 | u8 v; | |
8eed9260 CG |
81 | |
82 | if (sbf_port == -1) | |
1da177e4 | 83 | return 0; |
8eed9260 | 84 | |
1da177e4 | 85 | v = sbf_read(); |
8eed9260 CG |
86 | if (!sbf_value_valid(v)) { |
87 | printk(KERN_WARNING "Simple Boot Flag value 0x%x read from " | |
88 | "CMOS RAM was invalid\n", v); | |
89 | } | |
1da177e4 LT |
90 | |
91 | v &= ~SBF_RESERVED; | |
92 | v &= ~SBF_BOOTING; | |
93 | v &= ~SBF_DIAG; | |
94 | #if defined(CONFIG_ISAPNP) | |
95 | v |= SBF_PNPOS; | |
96 | #endif | |
97 | sbf_write(v); | |
8eed9260 | 98 | |
1da177e4 LT |
99 | return 0; |
100 | } | |
1da177e4 | 101 | module_init(sbf_init); |