| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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); |