board/raspberrypi: add Raspberry Pi Zero 2 W

The Raspberry-Pi Zero 2 W is an affordable single board computer. It is
a more powerful drop-in replacement for the Raspberry Pi Zero W.

The board incorporates an Raspberry-Pi RP3A0 system-in-package (SiP) with
a Broadcom BCM2710A1 and 512MB LPDDR2 SDRAM. The CPU is a quad-core 1Ghz
64-bit Arm Cortex-A53. As for other Raspberry-Pis it also provides
2.4GHz 802.11 b/g/n Wifi, Bluetooth 4.2 and BLE.

The BCM2710 cpu is similar to the Raspberry-Pi 3, it uses the same
kernel configuration as the Raspberry-Pi 2 and 3.

Signed-off-by: Julien Grossholtz <julien.grossholtz@openest.io>
[Based on https://patchwork.ozlabs.org/project/buildroot/patch/20211030213600.3445223-3-julien.grossholtz@openest.io/
  - reformat genimage-raspberrypizero2w.cfg according to the beautify patch-set
  - update kernel version to 9878a11 (5.10.78)
  - use new bcm2710-rpi-zero-2-w dtb
  - update commit log about kernel config (RPi2/3)
  - add DEVELOPERS entries for Julien
]
Signed-off-by: Peter Seiderer <ps.report@gmx.net>

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

DEVELOPERS

@@ -1512,7 +1512,9 @@ N:	Julien Corjon <corjon.j@ecagroup.com>
 F:	package/qt5/
 
 N:	Julien Grossholtz <julien.grossholtz@openest.io>
+F:	board/raspberrypi/
 F:	board/technologic/ts7680/
+F:	configs/raspberrypizero2w_defconfig
 F:	configs/ts7680_defconfig
 F:	package/paho-mqtt-c
 

board/raspberrypi/config_zero2w.txt

@@ -0,0 +1,29 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start.elf
+fixup_file=fixup.dat
+
+kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B ,zero W and zero 2) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+
+# enable autoprobing of Bluetooth driver without need of hciattach/btattach
+dtoverlay=krnbt=on

board/raspberrypi/genimage-raspberrypizero2w.cfg

@@ -0,0 +1,32 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2710-rpi-zero-2-w.dtb",
+			"rpi-firmware/bootcode.bin",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup.dat",
+			"rpi-firmware/start.elf",
+			"rpi-firmware/overlays",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/readme.txt

@@ -28,6 +28,10 @@ For model Zero (model A+ in smaller form factor):
 
   $ make raspberrypi0_defconfig
 
+For model Zero 2 W (model B3 in smaller form factor):
+
+  $ make raspberrypizero2w_defconfig
+
 For model 2 B:
 
   $ make raspberrypi2_defconfig
@@ -79,6 +83,7 @@ After building, you should obtain this tree:
     +-- bcm2708-rpi-cm.dtb          [1]
     +-- bcm2708-rpi-zero.dtb        [1]
     +-- bcm2708-rpi-zero-w.dtb      [1]
+    +-- bcm2710-rpi-zero-2-w.dtb    [1]
     +-- bcm2709-rpi-2-b.dtb         [1]
     +-- bcm2710-rpi-3-b.dtb         [1]
     +-- bcm2710-rpi-3-b-plus.dtb    [1]

board/raspberrypizero2w

@@ -0,0 +1 @@
+raspberrypi

configs/raspberrypizero2w_defconfig

@@ -0,0 +1,36 @@
+BR2_arm=y
+BR2_cortex_a53=y
+BR2_ARM_FPU_NEON_VFPV4=y
+
+# Linux headers same as kernel, 5.10 series
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_10=y
+
+BR2_TOOLCHAIN_BUILDROOT_CXX=y
+
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
+BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="$(call github,raspberrypi,linux,9878a118cbdb7779fd15caa45915d22bff381ba3)/linux-9878a118cbdb7779fd15caa45915d22bff381ba3.tar.gz"
+BR2_LINUX_KERNEL_DEFCONFIG="bcm2709"
+
+# Build the DTB from the kernel sources
+BR2_LINUX_KERNEL_DTS_SUPPORT=y
+BR2_LINUX_KERNEL_INTREE_DTS_NAME="bcm2710-rpi-zero-2-w"
+BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
+
+BR2_PACKAGE_RPI_FIRMWARE=y
+BR2_PACKAGE_RPI_FIRMWARE_BOOTCODE_BIN=y
+BR2_PACKAGE_RPI_FIRMWARE_VARIANT_PI=y
+BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE="board/raspberrypizero2w/config_zero2w.txt"
+
+# MicroSD images generation tools
+BR2_PACKAGE_HOST_DOSFSTOOLS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_MTOOLS=y
+
+# Filesystem / image
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_ROOTFS_POST_BUILD_SCRIPT="board/raspberrypizero2w/post-build.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/raspberrypizero2w/post-image.sh"