payloads/external: add skiboot (for QEMU/Power9)

Add an option to build skiboot as a payload. This makes QEMU Power9
board simpler to use as skiboot is necessary anyway.

Change-Id: I0b49ea7464c97cc2ff0d5030629deed549851372
Signed-off-by: Igor Bagnucki <igor.bagnucki@3mdeb.com>
Signed-off-by: Krystian Hebel <krystian.hebel@3mdeb.com>
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58656
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>

Documentation/mainboard/emulation/qemu-power9.md

@@ -1,7 +1,19 @@
 # QEMU PPC64 emulator
 This page describes how to build and run coreboot for QEMU/PPC64.
-You can configure ELF payload via `make menuconfig` (make sure "ROM chip size"
-is large enough).
+
+## Building coreboot
+```bash
+make defconfig KBUILD_DEFCONFIG=configs/config.emulation_qemu_power9
+make
+```
+
+This builds coreboot with no payload.
+
+## Payloads
+You can configure ELF or `skiboot` payload via `make menuconfig`. In either case
+you might need to adjust "ROM chip size" and make it large enough to accommodate
+the payload (see how much space it needs in the error you get if it doesn't
+fit).
 
 ## Running coreboot in QEMU
 ```bash
@@ -15,16 +27,26 @@ qemu-system-ppc64 -M powernv,hb-mode=on \
 
 - The default CPU in QEMU for AArch64 is a 604. You specify a suitable
 PowerPC CPU via `-cpu power9`.
-- By default Hostboot mode is off and it needs to be turned on to run coreboot
+- By default Hostboot mode is off and needs to be turned on to run coreboot
 as a firmware rather than like an OS.
 - `-bios` specifies initial program (bootloader should suffice, but whole image
 works fine too).
 - `-drive` specifies image for emulated flash device.
 
-## Building coreboot
+## Running with a kernel
+Loading `skiboot` (built automatically by coreboot or otherwise) allows
+specifying kernel and root file system to be run.
+
 ```bash
-make defconfig KBUILD_DEFCONFIG=configs/config.emulation_qemu_power9
-make
+qemu-system-ppc64 -M powernv,hb-mode=on \
+                  -cpu power9 \
+                  -bios build/coreboot.rom \
+                  -drive file=build/coreboot.rom,if=mtd \
+                  -serial stdio \
+                  -display none \
+                  -kernel zImage \
+                  -initrd initrd.cpio.xz
 ```
 
-This builds coreboot with no payload.
+- Specify path to your kernel via `-kernel`.
+- Specify path to your rootfs via `-initrd`.

payloads/Makefile.inc

@@ -28,6 +28,7 @@ payloads/external/tianocore \
 payloads/external/GRUB2 \
 payloads/external/LinuxBoot \
 payloads/external/Yabits \
+payloads/external/skiboot \
 
 force-payload:
 

payloads/external/.gitignore

@@ -8,3 +8,5 @@ tint/tint/
 U-Boot/u-boot/
 Memtest86Plus/memtest86plus/
 iPXE/ipxe/
+skiboot/skiboot
+skiboot/build

payloads/external/Makefile.inc

@@ -332,3 +332,10 @@ payloads/external/Yabits/uefi/build/uefi.elf yabits:
 
 payloads/external/BOOTBOOT/bootboot/dist/bootbootcb.elf:
 	$(MAKE) -C payloads/external/BOOTBOOT all
+
+# skiboot
+
+payloads/external/skiboot/build/skiboot.elf:
+	$(MAKE) -C payloads/external/skiboot all \
+		CONFIG_SKIBOOT_GIT_REPO=$(CONFIG_SKIBOOT_GIT_REPO) \
+		CONFIG_SKIBOOT_REVISION=$(CONFIG_SKIBOOT_REVISION)

payloads/external/skiboot/Kconfig

@@ -0,0 +1,21 @@
+## SPDX-License-Identifier: GPL-2.0-only
+
+if PAYLOAD_SKIBOOT
+
+config PAYLOAD_FILE
+	default "payloads/external/skiboot/build/skiboot.elf"
+
+config SKIBOOT_GIT_REPO
+	string "Git repository of skiboot payload"
+	default "https://github.com/open-power/skiboot"
+	help
+	  Git repository which will be used to clone skiboot.
+
+config SKIBOOT_REVISION
+	string "Revision of skiboot payload"
+	default "d93ddbd39b4eeac0bc11dacbdadea76df2996c13" if BOARD_EMULATION_QEMU_POWER9
+	help
+	  Revision, that skiboot repository will be checked out to, before building
+	  an image.
+
+endif # PAYLOAD_SKIBOOT

payloads/external/skiboot/Kconfig.name

@@ -0,0 +1,8 @@
+## SPDX-License-Identifier: GPL-2.0-only
+
+config PAYLOAD_SKIBOOT
+	bool "skiboot"
+	depends on ARCH_PPC64
+	help
+	  Select this option if you want to build a coreboot image
+	  with a skiboot payload.

payloads/external/skiboot/Makefile

@@ -0,0 +1,36 @@
+## SPDX-License-Identifier: GPL-2.0-only
+
+build_dir=$(CURDIR)/build
+skiboot_dir=$(CURDIR)/skiboot
+skiboot_git_repo=$(CONFIG_SKIBOOT_GIT_REPO)
+skiboot_revision=$(CONFIG_SKIBOOT_REVISION)
+skiboot_elf=$(build_dir)/skiboot.elf
+skiboot_cross=$(or $(CROSS),powerpc64-linux-gnu-)
+
+unexport $(COREBOOT_EXPORTS)
+
+.PHONY: all clean distclean
+
+all: $(skiboot_elf)
+
+$(skiboot_elf): | $(skiboot_dir) $(build_dir)
+	+$(MAKE) -C $(skiboot_dir) CROSS="$(skiboot_cross)"
+	cp $(skiboot_dir)/skiboot.elf $@
+	# skiboot is always built with debug information due to unconditional -ggdb
+	$(skiboot_cross)strip $@
+
+$(skiboot_dir):
+	git clone $(skiboot_git_repo) $(skiboot_dir)
+	git -C $(skiboot_dir) checkout $(skiboot_revision)
+
+$(build_dir):
+	mkdir -p $(build_dir)
+
+distclean: clean
+	rm -rf $(skiboot_dir)
+
+clean:
+	# Redefine RM because it's used like `$(RM) non-existent-file`
+	# Also ignore useless messages about removing test files
+	[ ! -d $(skiboot_dir) ] || $(MAKE) -C $(skiboot_dir) RM="rm -rf" clean > /dev/null
+	rm -rf $(build_dir)

src/mainboard/emulation/qemu-power9/Kconfig

@@ -8,7 +8,7 @@ if BOARD_EMULATION_QEMU_POWER9
 config BOARD_SPECIFIC_OPTIONS
 	def_bool y
 	select CPU_POWER9
-	select BOARD_ROMSIZE_KB_512
+	select BOARD_ROMSIZE_KB_1024
 	select ARCH_BOOTBLOCK_PPC64
 	select ARCH_VERSTAGE_PPC64
 	select ARCH_ROMSTAGE_PPC64