Eric Lee / smarc-ti-linux-kernel

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arch/i386/kernel/bootflag.c 1.62 KB
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1da177e4c   Linus Torvalds   Linux-2.6.12-rc2 
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  /*
   *	Implement 'Simple Boot Flag Specification 2.0'
   */
1da177e4c   Linus Torvalds   Linux-2.6.12-rc2 
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  #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
  ", 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
  ",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);