#include <linux/io.h>
  #include <linux/module.h>
  
  /**
   *	check_signature		-	find BIOS signatures
   *	@io_addr: mmio address to check
   *	@signature:  signature block
   *	@length: length of signature
   *
   *	Perform a signature comparison with the mmio address io_addr. This
   *	address should have been obtained by ioremap.
   *	Returns 1 on a match.
   */
  
  int check_signature(const volatile void __iomem *io_addr,
  			const unsigned char *signature, int length)
  {
  	while (length--) {
  		if (readb(io_addr) != *signature)
  			return 0;
  		io_addr++;
  		signature++;
  	}
  	return 1;
  }
  EXPORT_SYMBOL(check_signature);