brcm2708: Implement sysupgrade

Implement sysupgrade for Raspberry Pi, similar to the way it is done on x86:
The config files are saved in the boot partition and moved to where they are
normally expected in preinit.

Also add optional gzip compression for the SD card image, since this can save
a lot of space (76M vs 6M), also similar to x86.

Signed-off-by: Bruno Randolf <br1@einfach.org>

SVN-Revision: 46347

target/linux/brcm2708/Makefile

@@ -19,7 +19,7 @@ SUBTARGETS:=bcm2708 bcm2709
 KERNEL_PATCHVER:=3.18
 
 include $(INCLUDE_DIR)/target.mk
-DEFAULT_PACKAGES += brcm2708-gpu-fw kmod-usb-hid kmod-sound-core kmod-sound-arm-bcm2835
+DEFAULT_PACKAGES += brcm2708-gpu-fw kmod-usb-hid kmod-sound-core kmod-sound-arm-bcm2835 kmod-fs-vfat kmod-nls-cp437 kmod-nls-iso8859-1
 
 define Target/Description
 	Build firmware image for Broadcom BCM2708/BCM2709 SoC devices.

target/linux/brcm2708/base-files/lib/preinit/79_move_config

+#!/bin/sh
+# Copyright (C) 2015 OpenWrt.org
+
+BOOTPART=/dev/mmcblk0p1
+
+move_config() {
+	if [ -b $BOOTPART ]; then
+		insmod nls_cp437
+		insmod nls_iso8859-1
+		insmod fat
+		insmod vfat
+		mount -t vfat -o rw,noatime $BOOTPART /mnt
+		[ -f /mnt/sysupgrade.tgz ] && mv -f /mnt/sysupgrade.tgz /
+		umount /mnt
+	fi
+}
+
+boot_hook_add preinit_mount_root move_config

target/linux/brcm2708/base-files/lib/upgrade/platform.sh

+platform_check_image() {
+	# i know no way to verify the image
+	return 0;
+}
+
+platform_do_upgrade() {
+	sync
+	get_image "$1" | dd of=/dev/mmcblk0 bs=2M conv=fsync
+	sleep 1
+}
+
+platform_copy_config() {
+	mount -t vfat -o rw,noatime /dev/mmcblk0p1 /mnt
+	cp -af "$CONF_TAR" /mnt/
+	sync
+	umount /mnt
+}

target/linux/brcm2708/image/Makefile

@@ -40,6 +40,9 @@ endef
 define Build/sdcard-img
 	./gen_rpi_sdcard_img.sh $@ $@.boot $(word 2,$^) \
 		$(CONFIG_BRCM2708_SD_BOOT_PARTSIZE) $(CONFIG_TARGET_ROOTFS_PARTSIZE)
+  ifneq ($(CONFIG_TARGET_IMAGES_GZIP),)
+	gzip -k -f9 $(BIN_DIR)/$(IMG_PREFIX)-sdcard-vfat-$(1).img
+  endif
 endef
 
 ### Device macros ###