1 files changed, 98 insertions, 0 deletions

diff --git a/arch/x86/kernel/bootflag.c b/arch/x86/kernel/bootflag.c
new file mode 100644
index 000000000000..0b9860530a6b
--- /dev/null
+++ b/arch/x86/kernel/bootflag.c
@@ -0,0 +1,98 @@
+/*
+ *      Implement 'Simple Boot Flag Specification 2.0'
+ */
+
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/acpi.h>
+#include <asm/io.h>
+
+#include <linux/mc146818rtc.h>
+
+
+#define SBF_RESERVED (0x78)
+#define SBF_PNPOS    (1<<0)
+#define SBF_BOOTING  (1<<1)
+#define SBF_DIAG     (1<<2)
+#define SBF_PARITY   (1<<7)
+
+
+int sbf_port __initdata = -1;   /* set via acpi_boot_init() */
+
+
+static int __init parity(u8 v)
+{
+        int x = 0;
+        int i;
+        
+        for(i=0;i<8;i++)
+        {
+                x^=(v&1);
+                v>>=1;
+        }
+        return x;
+}
+
+static void __init sbf_write(u8 v)
+{
+        unsigned long flags;
+        if(sbf_port != -1)
+        {
+                v &= ~SBF_PARITY;
+                if(!parity(v))
+                        v|=SBF_PARITY;
+
+                printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n", sbf_port, v);
+
+                spin_lock_irqsave(&rtc_lock, flags);
+                CMOS_WRITE(v, sbf_port);
+                spin_unlock_irqrestore(&rtc_lock, flags);
+        }
+}
+
+static u8 __init sbf_read(void)
+{
+        u8 v;
+        unsigned long flags;
+        if(sbf_port == -1)
+                return 0;
+        spin_lock_irqsave(&rtc_lock, flags);
+        v = CMOS_READ(sbf_port);
+        spin_unlock_irqrestore(&rtc_lock, flags);
+        return v;
+}
+
+static int __init sbf_value_valid(u8 v)
+{
+        if(v&SBF_RESERVED)              /* Reserved bits */
+                return 0;
+        if(!parity(v))
+                return 0;
+        return 1;
+}
+
+static int __init sbf_init(void)
+{
+        u8 v;
+        if(sbf_port == -1)
+                return 0;
+        v = sbf_read();
+        if(!sbf_value_valid(v))
+                printk(KERN_WARNING "Simple Boot Flag value 0x%x read from CMOS RAM was invalid\n",v);
+
+        v &= ~SBF_RESERVED;
+        v &= ~SBF_BOOTING;
+        v &= ~SBF_DIAG;
+#if defined(CONFIG_ISAPNP)
+        v |= SBF_PNPOS;
+#endif
+        sbf_write(v);
+        return 0;
+}
+
+module_init(sbf_init);