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