firmware: add microcode package for Intel

Compiling the Intel microcode package results in a
microcode.bin and a microcode-64.bin. As we can
decide based on the subtarget which should be used,
we'll only split the required .bin file with
iucode-tool.

x64 will get the intel-microcode-64.bin
All other variants will get intel-microcode.bin

The microcodes will be updated from preinit via a common
script - that's the earliest place where we can do it.

Signed-off-by: Zoltan HERPAI <wigyori@uid0.hu>

package/firmware/intel-microcode/Makefile

@@ -0,0 +1,49 @@
+#
+# Copyright (C) 2018 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=intel-microcode
+PKG_VERSION:=20170707
+PKG_RELEASE:=1~deb9u1
+
+PKG_SOURCE:=intel-microcode_3.$(PKG_VERSION).$(PKG_RELEASE).tar.xz
+PKG_SOURCE_URL:=http://ftp.debian.org/debian/pool/non-free/i/intel-microcode/
+PKG_HASH:=6e288b687077cbb678c90a1c2ab0cfba43ee46e8645dc3791884278f6453e927
+PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)-3.$(PKG_VERSION).$(PKG_RELEASE)
+
+PKG_BUILD_DEPENDS:=iucode-tool/host
+
+ifdef CONFIG_TARGET_x86_64
+	MICROCODE:="intel-microcode-64"
+else
+	MICROCODE:="intel-microcode"
+endif
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/intel-microcode
+  SECTION:=firmware
+  CATEGORY:=Firmware
+  URL:=$(PKG_SOURCE_URL)
+  DEPENDS:=@TARGET_x86 +iucode-tool
+  TITLE:=Intel x86 CPU microcode
+endef
+
+define Build/Compile
+	IUCODE_TOOL=$(STAGING_DIR)/../host/bin/iucode_tool $(MAKE) -C $(PKG_BUILD_DIR)
+	mkdir $(PKG_BUILD_DIR)/intel-ucode
+	$(STAGING_DIR)/../host/bin/iucode_tool -q \
+		--write-firmware=$(PKG_BUILD_DIR)/intel-ucode $(PKG_BUILD_DIR)/$(MICROCODE).bin
+endef
+
+define Package/intel-microcode/install
+	$(INSTALL_DIR) $(1)/lib/firmware/intel-ucode
+	$(INSTALL_DATA) $(PKG_BUILD_DIR)/intel-ucode/* $(1)/lib/firmware/intel-ucode
+endef
+
+$(eval $(call BuildPackage,intel-microcode))