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