gemini: Generate padded kernel+rootfs images for DIR-685

We currently generate a kernel that boots from the harddrive
in the DIR-685. That's not how we usually do things, so
let's augment it to boot from flash and mount the rootfs
using squashfs and JFFS2 like everyone else.

Partition splitting only work when the partitions are
inside of a "partitions" node which is why we have a patch
like this (submitted upstream).

Another patch drops the rootfs arguments and renames the
firmware partition while adding the compatible "wrg"
to it so the WRGG parser will kick in.

Factory image was tested by bravely reflashing the DIR-685
from stock firmware using the web UI and the serial console
boot loader.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

5 files changed, 174 insertions, 3 deletions

diff --git a/target/linux/gemini/config-4.14 b/target/linux/gemini/config-4.14
index 326b05c089..ef5900771e 100644
--- a/target/linux/gemini/config-4.14
+++ b/target/linux/gemini/config-4.14
@@ -277,6 +277,8 @@ CONFIG_MTD_CFI_STAA=y
 # CONFIG_MTD_COMPLEX_MAPPINGS is not set
 CONFIG_MTD_PHYSMAP=y
 CONFIG_MTD_PHYSMAP_OF_GEMINI=y
+CONFIG_MTD_SPLIT_FIRMWARE=y
+CONFIG_MTD_SPLIT_WRGG_FW=y
 CONFIG_MULTI_IRQ_HANDLER=y
 CONFIG_NAMESPACES=y
 CONFIG_NEED_DMA_MAP_STATE=y
diff --git a/target/linux/gemini/config-4.19 b/target/linux/gemini/config-4.19
index 7025ec149c..014175ea13 100644
--- a/target/linux/gemini/config-4.19
+++ b/target/linux/gemini/config-4.19
@@ -330,6 +330,8 @@ CONFIG_MTD_JEDECPROBE=y
 CONFIG_MTD_PHYSMAP=y
 CONFIG_MTD_PHYSMAP_OF_GEMINI=y
 CONFIG_MTD_REDBOOT_PARTS=y
+CONFIG_MTD_SPLIT_FIRMWARE=y
+CONFIG_MTD_SPLIT_WRGG_FW=y
 CONFIG_NAMESPACES=y
 CONFIG_NEED_DMA_MAP_STATE=y
 CONFIG_NEED_KUSER_HELPERS=y
diff --git a/target/linux/gemini/image/Makefile b/target/linux/gemini/image/Makefile
index 7fcac8051f..9dd37ab702 100644
--- a/target/linux/gemini/image/Makefile
+++ b/target/linux/gemini/image/Makefile
@@ -10,8 +10,8 @@ include $(INCLUDE_DIR)/image.mk
 # Cook a "WRGG" image, this board is apparently one in the D-Link
 # WRGG family and uses the exact same firmware format as other
 # D-Link devices.
-define Build/dir685-images
-	mkwrggimg -i $(IMAGE_KERNEL) \
+define Build/dir685-image
+	mkwrggimg -i $@ \
 	-o $@.new \
 	-d /dev/mtdblock/1 \
 	-s wrgns01_dlwbr_dir685RBWW \
@@ -22,6 +22,12 @@ define Build/dir685-images
 	mv $@.new $@
 endef
 
+# Padding added after the rootfs to an even 128k boundary
+# as this is 128k eraseblocks flash.
+define Build/dir685-pad-rootfs
+	$(STAGING_DIR_HOST)/bin/padjffs2 $(IMAGE_ROOTFS) -c 128 >>$@
+endef
+
 # Build D-Link DNS-313 images using the special header tool.
 # rootfs.tgz and rd.tgz contains nothing, we only need them
 # to satisfy the boot loader on the device. The zImage is
@@ -121,6 +127,16 @@ GEMINI_NAS_PACKAGES:=kmod-md-mod kmod-md-linear kmod-md-multipath \
 		samba36-server mdadm cfdisk fdisk e2fsprogs badblocks \
 		partx-utils
 
+# The DIR-685 flash layout is kernel in WRGG format, padded and followed
+# by the appended rootfs followed by some reasonable JFFS padding, the
+# remainder will be used by JFFS2 through overlayfs.
+#
+# - For the factory image, the WRGG image includes the rootfs so that the
+#   default firmware will flash it properly as all it knows is WRGG format.
+# - For the sysupgrade, we do not include the rootfs in the kernel image
+#   so it is not needelessly tossed into the RAM by the boot loader.
+#   This will be flashed from OpenWrt userland anyways so we only need
+#   the minimum to make the boot loader happy.
 define Device/dlink_dir-685
 	DEVICE_TITLE := D-Link DIR-685 Xtreme N Storage Router
 	DEVICE_DTS := gemini-dlink-dir-685
@@ -128,7 +144,8 @@ define Device/dlink_dir-685
 			kmod-switch-rtl8366rb swconfig \
 			kmod-rt2800-pci
 	IMAGES := factory.bin
-	IMAGE/factory.bin := dir685-images
+	# Pad to 128k erase blocks with 160 bytes WRGG header
+	IMAGE/factory.bin := append-kernel | pad-offset 128k 160 | append-rootfs | dir685-pad-rootfs | dir685-image
 endef
 TARGET_DEVICES += dlink_dir-685
 
diff --git a/target/linux/gemini/patches-4.19/0019-ARM-dts-gemini-Indent-DIR-685-partition-table.patch b/target/linux/gemini/patches-4.19/0019-ARM-dts-gemini-Indent-DIR-685-partition-table.patch
new file mode 100644
index 0000000000..b121ca174e
--- /dev/null
+++ b/target/linux/gemini/patches-4.19/0019-ARM-dts-gemini-Indent-DIR-685-partition-table.patch
@@ -0,0 +1,110 @@
+From 4a228ecf553e879bae384e634bb6413438e81a0e Mon Sep 17 00:00:00 2001
+From: Linus Walleij <linus.walleij@linaro.org>
+Date: Mon, 11 Mar 2019 15:43:05 +0100
+Subject: [PATCH 1/2] ARM: dts: gemini: Indent DIR-685 partition table
+
+It is discouraged to have OF partitions as subnodes directly
+under the device, create a "partitions" subnode and put the
+partitions inside it.
+
+Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
+---
+ arch/arm/boot/dts/gemini-dlink-dir-685.dts | 82 ++++++++++++----------
+ 1 file changed, 44 insertions(+), 38 deletions(-)
+
+diff --git a/arch/arm/boot/dts/gemini-dlink-dir-685.dts b/arch/arm/boot/dts/gemini-dlink-dir-685.dts
+index 9b2824816ddc..50ff65d95f26 100644
+--- a/arch/arm/boot/dts/gemini-dlink-dir-685.dts
++++ b/arch/arm/boot/dts/gemini-dlink-dir-685.dts
+@@ -267,44 +267,50 @@
+ 			/* 32MB of flash */
+ 			reg = <0x30000000 0x02000000>;
+ 
+-			/*
+-			 * This "RedBoot" is the Storlink derivative.
+-			 */
+-			partition@0 {
+-				label = "RedBoot";
+-				reg = <0x00000000 0x00040000>;
+-				read-only;
+-			};
+-			/*
+-			 * This firmware image contains the kernel catenated
+-			 * with the squashfs root filesystem. For some reason
+-			 * this is called "upgrade" on the vendor system.
+-			 */
+-			partition@40000 {
+-				label = "upgrade";
+-				reg = <0x00040000 0x01f40000>;
+-				read-only;
+-			};
+-			/* RGDB, Residental Gateway Database? */
+-			partition@1f80000 {
+-				label = "rgdb";
+-				reg = <0x01f80000 0x00040000>;
+-				read-only;
+-			};
+-			/*
+-			 * This partition contains MAC addresses for WAN,
+-			 * WLAN and LAN, and the country code (for wireless
+-			 * I guess).
+-			 */
+-			partition@1fc0000 {
+-				label = "nvram";
+-				reg = <0x01fc0000 0x00020000>;
+-				read-only;
+-			};
+-			partition@1fe0000 {
+-				label = "LangPack";
+-				reg = <0x01fe0000 0x00020000>;
+-				read-only;
++			partitions {
++				compatible = "fixed-partitions";
++				#address-cells = <1>;
++				#size-cells = <1>;
++
++				/*
++				 * This "RedBoot" is the Storlink derivative.
++				 */
++				partition@0 {
++					label = "RedBoot";
++					reg = <0x00000000 0x00040000>;
++					read-only;
++				};
++				/*
++				 * This firmware image contains the kernel catenated
++				 * with the squashfs root filesystem. For some reason
++				 * this is called "upgrade" on the vendor system.
++				 */
++				partition@40000 {
++					label = "upgrade";
++					reg = <0x00040000 0x01f40000>;
++					read-only;
++				};
++				/* RGDB, Residental Gateway Database? */
++				partition@1f80000 {
++					label = "rgdb";
++					reg = <0x01f80000 0x00040000>;
++					read-only;
++				};
++				/*
++				 * This partition contains MAC addresses for WAN,
++				 * WLAN and LAN, and the country code (for wireless
++				 * I guess).
++				 */
++				partition@1fc0000 {
++					label = "nvram";
++					reg = <0x01fc0000 0x00020000>;
++					read-only;
++				};
++				partition@1fe0000 {
++					label = "LangPack";
++					reg = <0x01fe0000 0x00020000>;
++					read-only;
++				};
+ 			};
+ 		};
+ 
+-- 
+2.20.1
+
diff --git a/target/linux/gemini/patches-4.19/0020-ARM-dts-Augment-DIR-685-partition-table-for-OpenWrt.patch b/target/linux/gemini/patches-4.19/0020-ARM-dts-Augment-DIR-685-partition-table-for-OpenWrt.patch
new file mode 100644
index 0000000000..bf044e0c69
--- /dev/null
+++ b/target/linux/gemini/patches-4.19/0020-ARM-dts-Augment-DIR-685-partition-table-for-OpenWrt.patch
@@ -0,0 +1,40 @@
+From 854934b0ce8e758ce581f5ddbc30e618ab46fbdb Mon Sep 17 00:00:00 2001
+From: Linus Walleij <linus.walleij@linaro.org>
+Date: Mon, 11 Mar 2019 15:44:29 +0100
+Subject: [PATCH 2/2] ARM: dts: Augment DIR-685 partition table for OpenWrt
+
+Rename the firmware partition so that the firmware MTD
+splitter will do its job, drop the rootfs arguments as
+the MTD splitter will set this up automatically.
+
+Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
+---
+ arch/arm/boot/dts/gemini-dlink-dir-685.dts | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+diff --git a/arch/arm/boot/dts/gemini-dlink-dir-685.dts b/arch/arm/boot/dts/gemini-dlink-dir-685.dts
+index 50ff65d95f26..7db30cc9d189 100644
+--- a/arch/arm/boot/dts/gemini-dlink-dir-685.dts
++++ b/arch/arm/boot/dts/gemini-dlink-dir-685.dts
+@@ -20,7 +20,7 @@
+ 	};
+ 
+ 	chosen {
+-		bootargs = "console=ttyS0,19200n8 root=/dev/sda1 rw rootwait consoleblank=300";
++		bootargs = "console=ttyS0,19200n8 consoleblank=300";
+ 		stdout-path = "uart0:19200n8";
+ 	};
+ 
+@@ -286,7 +286,8 @@
+ 				 * this is called "upgrade" on the vendor system.
+ 				 */
+ 				partition@40000 {
+-					label = "upgrade";
++					compatible = "wrg";
++					label = "firmware";
+ 					reg = <0x00040000 0x01f40000>;
+ 					read-only;
+ 				};
+-- 
+2.20.1
+