Commit | Line | Data |
---|---|---|
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> | |
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 | ||
1da177e4 LT |
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 | ||
1da177e4 LT |
21 | int sbf_port __initdata = -1; /* set via acpi_boot_init() */ |
22 | ||
1da177e4 LT |
23 | static int __init parity(u8 v) |
24 | { | |
25 | int x = 0; | |
26 | int i; | |
8eed9260 CG |
27 | |
28 | for (i = 0; i < 8; i++) { | |
29 | x ^= (v & 1); | |
30 | v >>= 1; | |
1da177e4 | 31 | } |
8eed9260 | 32 | |
1da177e4 LT |
33 | return x; |
34 | } | |
35 | ||
36 | static void __init sbf_write(u8 v) | |
37 | { | |
38 | unsigned long flags; | |
8eed9260 CG |
39 | |
40 | if (sbf_port != -1) { | |
1da177e4 | 41 | v &= ~SBF_PARITY; |
8eed9260 CG |
42 | if (!parity(v)) |
43 | v |= SBF_PARITY; | |
1da177e4 | 44 | |
8eed9260 CG |
45 | printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n", |
46 | sbf_port, v); | |
1da177e4 LT |
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 | { | |
1da177e4 | 56 | unsigned long flags; |
8eed9260 CG |
57 | u8 v; |
58 | ||
59 | if (sbf_port == -1) | |
1da177e4 | 60 | return 0; |
8eed9260 | 61 | |
1da177e4 LT |
62 | spin_lock_irqsave(&rtc_lock, flags); |
63 | v = CMOS_READ(sbf_port); | |
64 | spin_unlock_irqrestore(&rtc_lock, flags); | |
8eed9260 | 65 | |
1da177e4 LT |
66 | return v; |
67 | } | |
68 | ||
69 | static int __init sbf_value_valid(u8 v) | |
70 | { | |
8eed9260 | 71 | if (v & SBF_RESERVED) /* Reserved bits */ |
1da177e4 | 72 | return 0; |
8eed9260 | 73 | if (!parity(v)) |
1da177e4 | 74 | return 0; |
8eed9260 | 75 | |
1da177e4 LT |
76 | return 1; |
77 | } | |
78 | ||
79 | static int __init sbf_init(void) | |
80 | { | |
81 | u8 v; | |
8eed9260 CG |
82 | |
83 | if (sbf_port == -1) | |
1da177e4 | 84 | return 0; |
8eed9260 | 85 | |
1da177e4 | 86 | v = sbf_read(); |
8eed9260 CG |
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 | } | |
1da177e4 LT |
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); | |
8eed9260 | 99 | |
1da177e4 LT |
100 | return 0; |
101 | } | |
1da177e4 | 102 | module_init(sbf_init); |