configs/stm32f469_disco: fix kernel bootup

As described by [1], the kernel generated by the configuration for the
STM32f469 Discovery board is buggy. Using a newer kernel, as suggested
by [1], increases the dtb and Kernel image size. In particular, the
5.12 version of the kernel generates a dtb and a kernel image whose sum
exceeds the 2 MByte of the flash module.

So I decided to replace the afboot-stm32 bootloader in the flash with
U-boot to easily boot the system from sdcard without having to worry
about the size of dtb, kernel and rootfs generated by the configuration.

This solution allows you to fix the kernel boot issue and makes it
possible to use its future versions.

[1] http://buildroot-busybox.2317881.n4.nabble.com/Bug-11746-New-stm32f469-didn-t-work-correctly-td219644.html

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Acked-by: Christophe Priouzeau <christophe.priouzeau@foss.st.com>
Tested-by: Christophe Priouzeau <christophe.priouzeau@foss.st.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Arnout:
 - specify headers version explicitly, even though it's default;
 - bump kernel to 5.12.11]
(cherry picked from commit 04a0094f0ef0778d1f3c4056ac0005218126147e)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

board/stmicroelectronics/stm32f469-disco/extlinux.conf

@@ -0,0 +1,4 @@
+label stm32f469-disco-buildroot
+  kernel /zImage
+  devicetree /stm32f469-disco.dtb
+  append console=ttySTM0,115200 root=/dev/mmcblk0p2 rw rootfstype=ext2 rootwait earlyprintk consoleblank=0 ignore_loglevel

board/stmicroelectronics/stm32f469-disco/flash.sh

@@ -13,8 +13,6 @@ ${OUTPUT_DIR}/host/bin/openocd -f board/stm32f469discovery.cfg \
   -c "reset init" \
   -c "flash probe 0" \
   -c "flash info 0" \
-  -c "flash write_image erase ${OUTPUT_DIR}/images/stm32f469i-disco.bin 0x08000000" \
-  -c "flash write_image erase ${OUTPUT_DIR}/images/stm32f469-disco.dtb 0x08004000" \
-  -c "flash write_image erase ${OUTPUT_DIR}/images/xipImage 0x08008000" \
+  -c "flash write_image erase ${OUTPUT_DIR}/images/u-boot.bin 0x08000000" \
   -c "reset run" \
   -c "shutdown"

board/stmicroelectronics/stm32f469-disco/genimage.cfg

@@ -0,0 +1,27 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"zImage",
+			"stm32f469-disco.dtb",
+			"extlinux"
+		}
+	}
+	size = 16M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition u-boot {
+		partition-type = 0xC
+                image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext2"
+		size = 32M
+	}
+}
+

board/stmicroelectronics/stm32f469-disco/linux.fragment

@@ -0,0 +1 @@
+# CONFIG_XIP_KERNEL is not set

board/stmicroelectronics/stm32f469-disco/patches/linux/0001-ARM-stm32f249-disco-don-t-force-init-in-chosen-boota.patch

@@ -1,33 +0,0 @@
-From c8f8f33c2f0460a34c9545b01a7972a7ed2df0e9 Mon Sep 17 00:00:00 2001
-From: Christophe Priouzeau <christophe.priouzeau@st.com>
-Date: Mon, 29 May 2017 13:38:16 +0200
-Subject: [PATCH] ARM: stm32f249-disco: don't force init= in /chosen/bootargs
-
-There is no reason to override the kernel's default init= value, as
-this breaks userspace that assumes the kernel default of /init is
-used. Since stm32 is often used with a minimal bootloader
-(afboot-stm32) that doesn't provide any mechanism to override the DTB,
-we need to adjust the kernel command line in the Device Tree source.
-
-Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
-Signed-off-by: Christophe Priouzeau <christophe.priouzeau@st.com>
----
- arch/arm/boot/dts/stm32f469-disco.dts | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/arch/arm/boot/dts/stm32f469-disco.dts b/arch/arm/boot/dts/stm32f469-disco.dts
-index 0dd56ef..93ee1b2 100644
---- a/arch/arm/boot/dts/stm32f469-disco.dts
-+++ b/arch/arm/boot/dts/stm32f469-disco.dts
-@@ -53,7 +53,7 @@
- 	compatible = "st,stm32f469i-disco", "st,stm32f469";
- 
- 	chosen {
--		bootargs = "root=/dev/ram rdinit=/linuxrc";
-+		bootargs = "root=/dev/ram";
- 		stdout-path = "serial0:115200n8";
- 	};
- 
--- 
-2.7.4
-

board/stmicroelectronics/stm32f469-disco/post-build.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+BOARD_DIR="$(dirname $0)"
+
+install -m 0644 -D $BOARD_DIR/extlinux.conf $BINARIES_DIR/extlinux/extlinux.conf

board/stmicroelectronics/stm32f469-disco/readme.txt

@@ -15,5 +15,17 @@ Flashing
 
   ./board/stmicroelectronics/stm32f469-disco/flash.sh output/
 
-It will flash the minimal bootloader, the Device Tree Blob, and the
-kernel image which includes the root filesystem as initramfs.
+It will flash the U-boot bootloader.
+
+Creating SD card
+----------------
+
+Buildroot prepares an"sdcard.img" image in the output/images/ directory,
+ready to be dumped on a SD card. Launch the following command as root:
+
+  dd if=output/images/sdcard.img of=/dev/<your-sd-device>
+
+*** WARNING! This will destroy all the card content. Use with care! ***
+
+For details about the medium image layout and its content, see the
+definition in board/stmicroelectronics/stm32f469-disco/genimage.cfg.

configs/stm32f469_disco_defconfig

@@ -1,19 +1,23 @@
 BR2_arm=y
 BR2_cortex_m4=y
-BR2_GLOBAL_PATCH_DIR="board/stmicroelectronics/stm32f469-disco/patches"
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_11=y
-BR2_ROOTFS_POST_BUILD_SCRIPT="board/stmicroelectronics/common/stm32f4xx/stm32-post-build.sh"
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_12=y
+BR2_ROOTFS_POST_BUILD_SCRIPT="board/stmicroelectronics/common/stm32f4xx/stm32-post-build.sh board/stmicroelectronics/stm32f469-disco/post-build.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
+BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/stmicroelectronics/stm32f469-disco/genimage.cfg"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.11"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="5.12.11"
 BR2_LINUX_KERNEL_DEFCONFIG="stm32"
-BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="$(LINUX_DIR)/arch/arm/configs/dram_0x00000000.config"
+BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="$(LINUX_DIR)/arch/arm/configs/dram_0x00000000.config board/stmicroelectronics/stm32f469-disco/linux.fragment"
 BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM=y
-BR2_LINUX_KERNEL_IMAGE_TARGET_NAME="xipImage"
+BR2_LINUX_KERNEL_IMAGE_TARGET_NAME="zImage"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="stm32f469-disco"
 BR2_PACKAGE_BUSYBOX_CONFIG="package/busybox/busybox-minimal.config"
-BR2_TARGET_ROOTFS_INITRAMFS=y
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_SIZE="32M"
 # BR2_TARGET_ROOTFS_TAR is not set
-BR2_TARGET_AFBOOT_STM32=y
+BR2_TARGET_UBOOT=y
+BR2_TARGET_UBOOT_BOARD_DEFCONFIG="stm32f469-discovery"
+BR2_PACKAGE_HOST_GENIMAGE=y
 BR2_PACKAGE_HOST_OPENOCD=y