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