Allow each target to define the way to obtain its MAC address

At the moment only 2 targets defines it:
PandABlocks: MAC from a qspi memory
PAndABrick: MAC from a secure EEPROM

This is part of a solution for issue #67

common/fpga.make

@@ -99,7 +99,7 @@ carrier_ip: $(APP_IP_DEPS)
 ps_core: $(PS_CORE)
 devicetree : $(DEVTREE_DTB)
 fsbl : $(FSBL)
-boot : $(BOOT_ZIP) $(IMAGE_DIR)/boot.bin $(DEVTREE_DTB)
+boot : $(BOOT_ZIP) $(IMAGE_DIR)/boot.bin $(DEVTREE_DTB) $(IMAGE_DIR)/target-functions
 u-boot: $(U_BOOT_ELF)
 atf: $(ATF_ELF)
 dtc: $(DEVTREE_DTC)
@@ -247,6 +247,9 @@ $(DEVTREE_DTB): $(SDK_EXPORT) $(TARGET_DTS) $(DEVTREE_DTC)
 	@echo "Building DEVICE TREE blob ..."
 	$(DEVTREE_DTC) -f -I dts -O dtb -o $@ $(DEVTREE_DTS)/$(notdir $(TARGET_DTS))
 
+$(IMAGE_DIR)/target-functions: $(TARGET_DIR)/etc/target-functions
+	cp $< $@
+
 $(DEVTREE_DTC): $(DTC_SRC)
 	$(MAKE) -C $(SRC_ROOT)/dtc-$(DTC_TAG) NO_PYTHON=1
 

targets/PandABox/etc/target-functions

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+get_mac_address()
+{
+    cat /qspi/MAC
+}

targets/PandABrick/etc/target-functions

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+get_mac_address() {
+    # Trying to address 0 sends a 0 byte which wakes up the EEPROM
+    i2ctransfer -a -y 0 r1@0x0 &>/dev/null
+    # Send command to read 32 bytes of OTP zone starting at offset 0
+    i2ctransfer -y 0 w8@0x64  0x3 0x7 0x2 0x81 0x0 0x0 0x0a 0x27
+    resp=$(i2ctransfer -y 0 r35@0x64)
+    # Extract the MAC address and format it
+    resp=${resp:85:29}
+    resp=${resp//0x/}
+    resp=${resp// /:}
+    echo $resp
+}