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