proc xilinx_dna_addr {chip} {
	array set addrs {
		Spartan6 0x30
		Series7 0x17
	}
	return $addrs($chip)
}

# Get the "Device DNA".
# Most Xilinx FPGA devices contain an embedded, unique device identifier.
# The identifier is nonvolatile, permanently programmed into
# the FPGA, and is unchangeable providing a great serial / tracking number.
# This function returns the DNA as a 64 bit integer with the 7 LSBs zeroed.
# This is compatible with the FUSE DNA which contains all 64 bits.
proc xilinx_get_dna {tap chip} {
	set XC7_ISC_ENABLE 0x10
	set XC7_ISC_DISABLE 0x16
	set XC7_ISC_DNA [xilinx_dna_addr $chip]

	irscan $tap $XC7_ISC_ENABLE
	runtest 64
	irscan $tap $XC7_ISC_DNA
	scan [drscan $tap 32 0 32 0] "%08x %08x" hi lo
	runtest 64
	irscan $tap $XC7_ISC_DISABLE
	runtest 64
	# openocd interprets DR scans as LSB first, bit-reverse it
	return [scan [string reverse [format "%032b%032bb0" $lo $hi]] "%i"]
}

# Print out the "Device DNA" in the same format that impact uses.
proc xilinx_print_dna {dna} {
	set dna [expr $dna >> 64 - 57]
	echo [format "DNA = %057b (0x%016x)" $dna $dna]
}

proc xc7_get_dna {tap} {
	return [xilinx_get_dna $tap Series7]
}

proc xc6s_get_dna {tap} {
	return [xilinx_get_dna $tap Spartan6]
}
