gemini: create a copy-kernel for 3072k kernels

The Raidsonic devices do not use a 2048k kernel "Kern"
partition like the Storlink reference designs. Instead
it uses a 3072k partition to fit a slightly
larger kernel.

Sadly the current OpenWrt Gemini kernel is still bigger
than 3072k so we need to make use of the Ramdisk
partition as well.

Create a special "copy-kernel" version that can deal
with the Raidsonic 3072k kernels. Tested on the
Raidsonic IB-4220-B booting kernel v6.12.66.

Fix a copy/paste error in the image generation makefile
while we are at it.

Link: https://github.com/openwrt/openwrt/pull/21686
Signed-off-by: Linus Walleij <[email protected]>

target/linux/gemini/image/Makefile

@@ -94,14 +94,13 @@ define CreateStorlinkTarfile
 
 	# "Application" partition is the rootfs
 	mv $@ [email protected]/hddapp.tgz
-	# 256 bytes copy routine
-	# TODO fix for IB-4220-B
-	dd if=$(KDIR)/copy-kernel.bin [email protected]/zImage
+	# 512 bytes copy routine
+	dd if=$(KDIR)/copy-kernel-$(2).bin [email protected]/zImage
 	$(call Image/pad-to,[email protected]/zImage,512)
 	# Copy first part of the kernel into zImage
-	dd if=$(IMAGE_KERNEL) [email protected]/zImage bs=1 seek=512 count=$(2)
+	dd if=$(IMAGE_KERNEL) [email protected]/zImage bs=1 seek=512 count=$(3)
 	# Put the rest of the kernel into the "ramdisk"
-	dd if=$(IMAGE_KERNEL) [email protected]/rd.gz bs=1 skip=$(2) count=6144k conv=sync
+	dd if=$(IMAGE_KERNEL) [email protected]/rd.gz bs=1 skip=$(3) count=6144k conv=sync
 	cp ./ImageInfo-$(1) [email protected]/ImageInfo
 
 	sed -i -e "s/DATESTR/`date +%Y%m%d $(if $(SOURCE_DATE_EPOCH),--date "@$(SOURCE_DATE_EPOCH)")`/g" [email protected]/ImageInfo
@@ -115,12 +114,12 @@ endef
 
 # 2048k "Kern" partition
 define Build/storlink-default-image
-	$(call CreateStorlinkTarfile,$(1),2096640)
+	$(call CreateStorlinkTarfile,$(1),2048k,2096640)
 endef
 
-# 3032k "Kern" partition
+# 3072k "Kern" partition
 define Build/raidsonic-ib-4220-b-image
-	$(call CreateStorlinkTarfile,$(1),3145216)
+	$(call CreateStorlinkTarfile,$(1),3072k,3145216)
 endef
 
 # WBD-111 and WBD-222:
@@ -228,7 +227,7 @@ define Device/raidsonic_ib-4220-b
 	# Application  6144k       | = 15360k
 	IMAGE/factory.bin := append-rootfs | pad-rootfs | pad-to 6144k | \
 		raidsonic-ib-4220-b-image $(1)
-	IMAGE/factory.bin := append-rootfs | pad-rootfs | pad-to 6144k | \
+	IMAGE/sysupgrade.bin := append-rootfs | pad-rootfs | pad-to 6144k | \
 		raidsonic-ib-4220-b-image $(1) | append-metadata
 endef
 TARGET_DEVICES += raidsonic_ib-4220-b

target/linux/gemini/image/copy-kernel/Makefile

@@ -16,7 +16,7 @@ BIN_FLAGS	:= -O binary -S
 SRC_DIR		:= $(CURDIR)/
 OUT_DIR		:= $(if $(O),$(if $(patsubst %/,,$(O)),$(O)/,$(O)),$(SRC_DIR))
 
-all: $(OUT_DIR)copy-kernel.bin
+all: $(OUT_DIR)copy-kernel-2048k.bin $(OUT_DIR)copy-kernel-3072k.bin
 
 # Don't build dependencies, this may die if $(CC) isn't gcc
 dep:
@@ -35,4 +35,5 @@ $(OUT_DIR)%.bin: $(OUT_DIR)%.o
 mrproper: clean
 
 clean:
-	rm -f $(OUT_DIR)copy-kernel.bin $(OUT_DIR)copy-kernel.o
+	rm -f $(OUT_DIR)copy-kernel-2048k.bin $(OUT_DIR)copy-kernel-2048k.o
+	rm -f $(OUT_DIR)copy-kernel-3072k.bin $(OUT_DIR)copy-kernel-3072k.o

target/linux/gemini/image/copy-kernel/copy-kernel-3072k.S

@@ -0,0 +1,45 @@
+	// Arm assembly to copy the Gemini kernel on Raidsonic
+	// designs and derived devices with the same flash layout and
+	// boot loader.
+	//
+	// This will execute at 0x01600000
+	//
+	// Copies the kernel from two fragments (originally zImage
+	// and initramdisk) to 0x00400000 making space for a kernel
+	// image of up to 8 MB except for these 512 bytes used for
+	// this bootstrap.
+	//
+	// 0x01600200 .. 0x018fffff -> 0x00400000 .. 0x006ffdff
+	// 0x00800000 .. 0x00dfffff -> 0x006ffe00 .. 0x00cffdff
+
+	// Memory used for this bootstrap
+	.equ BOOT_HEADROOM,	0x200
+
+	.global _start // Stand-alone assembly code
+_start:
+	mov r1, #0x01600000
+	mov r2, #0x00400000
+	mov r3, #0x00300000
+	add r1, r1, #BOOT_HEADROOM
+	sub r3, r3, #BOOT_HEADROOM
+copyloop1:
+	ldr r0, [r1]
+	str r0, [r2]
+	add r1, r1, #4
+	add r2, r2, #4
+	sub r3, r3, #4
+	cmp r3, #0
+	bne copyloop1
+	mov r1, #0x00800000
+	mov r3, #0x00600000
+copyloop2:
+	ldr r0, [r1]
+	str r0, [r2]
+	add r1, r1, #4
+	add r2, r2, #4
+	sub r3, r3, #4
+	cmp r3, #0
+	bne copyloop2
+	mov r0, #0x00400000
+	// Let's go
+	mov pc, r0