Generate a usable binary file for flashrom

rtl/Makefile

@@ -3,9 +3,11 @@
 NEXTPNR_OPTS=--up5k --package sg48
 ICETIME_OPTS=-d up5k
 FN=bldc
+FLASH_SIZE=524288
 
-${FN}.bin: ${FN}.asc
-	icepack ${FN}.asc ${FN}.bin
+${FN}_filled.bin: ${FN}.bin
+	python3 -c "import sys; sys.stdout.buffer.write(b'\xff'*${FLASH_SIZE})" > $@;
+	dd if=$< of=$@ conv=notrunc
 
 ${FN}.json: ${FN}.v
 	./run_yosys.sh ${FN}
@@ -16,7 +18,12 @@ ${FN}.asc: ${FN}.json ${FN}.pcf
 #${FN}.rpt: ${FN}.pcf ${FN}.txt
 #	icetime $ICETIME_OPTS -p "${FN}.pcf" -mtr "${FN}.rpt" "${FN}.txt"
 
-clean:
-	rm ${FN}.json ${FN}.asc ${FN}.bin
+${FN}.bin: ${FN}.asc
+	icepack ${FN}.asc ${FN}.bin
 
-flash: $FN.bin
+
+clean:
+	rm ${FN}.json ${FN}.asc ${FN}.bin ${FN}_filled.bin
+
+flash: ${FN}_filled.bin
+	flashrom -p ft2232_spi:type=232H,port=A -w "${FN}_filled.bin"