NAND Support
Thanks to Boris Brezillon, Linux supports the Toshiba NAND used on some CHIPs in emulated SLC mode since version 5.8. Chris Morgan added SLC mode support for the Hynix NAND on the original CHIP in Linux version 5.16.
Unfortunately, U-Boot at the time of writing does not support the NAND memory on CHIP out of the box. However, Chris Morgan also provides patches for U-Boot v2022.01 in his chip-debroot repository on Github.
In this chapter we'll first setup Linux to use CHIP's NAND in SLC mode, then switch to the patched version of U-Boot 2022.01 which supports the NAND in SLC mode and finally write special bootloader and rootfs images that allow for booting CHIP from the NAND.
Access the NAND from Linux
Linux Configuration
So far, we've used the sunxi_defconfig in the Linux tree. Let's enable
the so-called Memory Technology Device (MTD) drivers and support for raw NAND and
the Allwinner NAND controller as well as UBI/UBIFS. Type:
export UBOOT_VER=2024.10
export LINUX_VER=6.6.63
export BR=buildroot-2024.02.08
cd "${BR}"
make linux-nconfig
Then select:
Device Drivers --->
<*> Memory Technology Device (MTD) support --->
Partition parsers --->
<*> Command line partition table parsing
<*> OpenFirmware (device tree) partitioning parser
NAND --->
<*> Raw/Parallel NAND Device Support --->
<*> Allwinner NAND controller
<*> Enable UBI - Unsorted block images --->
File systems --->
[*] Miscellaneous filesystems --->
<*> UBIFS file system support
Then save hit the output/build/linux-${LINUX_VER}/.config.
Alternatively, make sure these lines are in your Linux .config file:
CONFIG_MTD=y
CONFIG_MTD_CMDLINE_PARTS=y
CONFIG_MTD_RAW_NAND=y
CONFIG_MTD_NAND_SUNXI=y
CONFIG_MTD_UBI=y
CONFIG_MISC_FILESYSTEMS=y
CONFIG_UBIFS_FS=y
Save the configuration as Linux default configuration:
make linux-savedefconfig
cp output/build/linux-${LINUX_VER}/defconfig ../buildroot-external/board/nextthingco/CHIP/linux/chip_defconfig
The device tree for CHIP included in the Linux source do not enable the NAND.
We need to create a patch that we place in buildroot-external/board/nextthingco/CHIP/sun5i-r8-chip.dts.nand.patch:
cat <<EOF >../buildroot-external/board/nextthingco/CHIP/linux/sun5i-r8-chip.dts.nand.patch
--- a/arch/arm/boot/dts/allwinner/sun5i-r8-chip.dts 2024-11-27 11:25:04.172206469 +0100
+++ b/arch/arm/boot/dts/allwinner/sun5i-r8-chip.dts 2024-12-02 10:34:49.783858862 +0100
@@ -280,3 +280,44 @@
usb0_vbus-supply = <®_usb0_vbus>;
usb1_vbus-supply = <®_vcc5v0>;
};
+
+&nfc {
+ pinctrl-names = "default";
+ pinctrl-0 = <&nand_pins &nand_cs0_pin &nand_rb0_pin>;
+ status = "okay";
+
+ nand@0 {
+ #address-cells = <2>;
+ #size-cells = <2>;
+ reg = <0>;
+ allwinner,rb = <0>;
+ nand-ecc-mode = "hw";
+ nand-ecc-maximize;
+ nand-on-flash-bbt;
+ spl@0 {
+ label = "SPL";
+ reg = /bits/ 64 <0x0 0x400000>;
+ };
+
+ spl-backup@400000 {
+ label = "SPL.backup";
+ reg = /bits/ 64 <0x400000 0x400000>;
+ };
+
+ u-boot@800000 {
+ label = "U-Boot";
+ reg = /bits/ 64 <0x800000 0x400000>;
+ };
+
+ env@c00000 {
+ label = "env";
+ reg = /bits/ 64 <0xc00000 0x400000>;
+ };
+
+ rootfs@1000000 {
+ label = "rootfs";
+ reg = /bits/ 64 <0x1000000 0x1ff000000>;
+ slc-mode;
+ };
+ };
+};
EOF
NOTE: We're hardcoding 5 partiions here: spl (4MB), spl-backup (4MB), u-boot (4MB), env (4MB) and rootfs (remaining space, slc-mode).
Buildroot is going to automatically apply the patch the next time we build.
Let's add some file system utilities to the Buildroot configuration - type:
make nconfig
Then select mtd, jffs2 and ubi/ubifs tools and make sure the mkfs.ubifs is also selected:
Target packages --->
Filesystem and flash utilities --->
[*] mtd, jffs2 and ubi/ubifs tools
*** MTD tools selection ***
[ ] docfdisk
[ ] doc_loadbios
[*] flashcp
[*] flash_erase
[*] flash_lock
[ ] flash_otp_dump
[ ] flash_otp_info
[ ] flash_otp_lock
[ ] flash_otp_write
[ ] flash_otp_erase
[*] flash_unlock
[ ] ftl_check
[ ] ftl_format
[ ] jffs2dump
[ ] lsmtd
[ ] mkfs.jffs2
[*] mkfs.ubifs
Then save hit the .config.
Save the configuration as Buildroot default configuration for CHIP and build the new Linux kernel and the new rootfs:
make savedefconfig
make
Boot into our new OS image:
cd output/images
sunxi-fel -v -p uboot u-boot-sunxi-with-spl.bin \
write 0x42000000 zImage \
write 0x43000000 sun5i-r8-chip.dtb \
write 0x50000000 rootfs.cpio.uboot
In U-Boot, boot:
bootz 0x42000000 0x50000000 0x43000000
Format the root partition:
mtdinfo
mtdinfo /dev/mtd0
flash_erase /dev/mtd5 0 2035
ubiformat /dev/mtd5
ubiattach -m 5 # --> generates /dev/ubi0, also displays number of LEBs = e.g. 1952
ubimkvol /dev/ubi0 --name rootfs -S 1952 # --> creates /dev/ubi0_0
mkfs.ubifs /dev/ubi0_0 # --> doesn't really create ubifs
mount -t ubifs /dev/ubi0_0 /mnt # --> ubifs is created as part of mounting
cp -va /bin /usr /mnt/ # --> copy stuff from ramdisk to nand
reboot
NOTE: leaving out the mkfs.ubifs /dev/ubi0_0 step above seems to work fine as long as only Linux is involved.
However, we won't be able to mount the ubifs partition from U-Boot without!
In the U-Boot terminal type:
bootz 0x42000000 0x500000 0x43000000
In Linux, we now can read from NAND after reboot:
ubiattach -m 5 # --> generates /dev/ubi0
mount -t ubifs /dev/ubi0_0 /mnt # --> ubifs is created as part of mounting
find /mnt
U-Boot v2022.01
The patches from Chris Morgan are for U-Boot v2022.01. For simplicity, we are going to switch to that version as it allows us to use the unmodified patches. So let's create a new Buildroot configuration, in which we tell Buildroot to use U-Boot v2022.01, a custom U-Boot config file and define the directory for custom U-Boot patches:
export LINUX_VER=6.6.63
export UBOOT_VER=2022.01
cat <<EOF >../buildroot-external/configs/nextthingco_chip_defconfig
BR2_arm=y
BR2_cortex_a8=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_LINUX_KERNEL=y
BR2_LINUX_KERNEL_CUSTOM_VERSION=y
BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="${LINUX_VER}"
BR2_LINUX_KERNEL_PATCH="\${BR2_EXTERNAL_CHIP_PATH}/board/nextthingco/CHIP/linux"
BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="\${BR2_EXTERNAL_CHIP_PATH}/board/nextthingco/CHIP/linux/chip_defconfig"
BR2_LINUX_KERNEL_DTS_SUPPORT=y
BR2_LINUX_KERNEL_INTREE_DTS_NAME="allwinner/sun5i-r8-chip"
BR2_LINUX_KERNEL_DTB_OVERLAY_SUPPORT=y
BR2_LINUX_KERNEL_INSTALL_TARGET=y
BR2_PACKAGE_MTD=y
BR2_PACKAGE_MTD_MKFSUBIFS=y
BR2_TARGET_ROOTFS_CPIO=y
BR2_TARGET_ROOTFS_CPIO_GZIP=y
BR2_TARGET_ROOTFS_CPIO_UIMAGE=y
BR2_TARGET_UBOOT=y
BR2_TARGET_UBOOT_BUILD_SYSTEM_KCONFIG=y
BR2_TARGET_UBOOT_CUSTOM_VERSION=y
BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="${UBOOT_VER}"
BR2_TARGET_UBOOT_PATCH="\${BR2_EXTERNAL_CHIP_PATH}/board/nextthingco/CHIP/uboot"
BR2_TARGET_UBOOT_USE_CUSTOM_CONFIG=y
BR2_TARGET_UBOOT_CUSTOM_CONFIG_FILE="\${BR2_EXTERNAL_CHIP_PATH}/board/nextthingco/CHIP/uboot/CHIP_defconfig"
BR2_TARGET_UBOOT_NEEDS_DTC=y
BR2_TARGET_UBOOT_NEEDS_PYLIBFDT=y
BR2_TARGET_UBOOT_SPL=y
BR2_TARGET_UBOOT_SPL_NAME="u-boot-sunxi-with-spl.bin spl/u-boot-spl.bin"
EOF
make nextthingco_chip_defconfig
Download patches to enable SLC mode for the NAND:
wget -c -P ../buildroot-external/board/nextthingco/CHIP/uboot https://raw.githubusercontent.com/macromorgan/chip-debroot/main/u-boot_files/0001-sunxi-Add-support-for-slc-emulation-on-mlc-NAND.patch
wget -c -P ../buildroot-external/board/nextthingco/CHIP/uboot https://raw.githubusercontent.com/macromorgan/chip-debroot/main/u-boot_files/0001-sunxi-nand-Undo-removal-of-DMA-specific-code-that-br.patch
Create a CHIP_defconfig for U-Boot:
cat <<EOF >../buildroot-external/board/nextthingco/CHIP/uboot/CHIP_defconfig
CONFIG_ARM=y
CONFIG_ARCH_SUNXI=y
CONFIG_DEFAULT_DEVICE_TREE="sun5i-r8-chip"
CONFIG_SPL=y
CONFIG_MACH_SUN5I=y
CONFIG_DRAM_TIMINGS_DDR3_800E_1066G_1333J=y
CONFIG_USB0_VBUS_PIN="PB10"
CONFIG_VIDEO_COMPOSITE=y
CONFIG_CHIP_DIP_SCAN=y
CONFIG_SPL_I2C=y
CONFIG_CMD_DFU=y
CONFIG_CMD_MTDPARTS=y
CONFIG_MTDIDS_DEFAULT="nand0=nand0"
CONFIG_MTDPARTS_DEFAULT="nand0:0x400000(SPL),0x400000(SPL.backup),0x400000(U-Boot),0x400000(U-Boot.backup),-(rootfs)slc"
CONFIG_DFU_RAM=y
CONFIG_SYS_I2C_MVTWSI=y
CONFIG_SYS_I2C_SLAVE=0x7f
CONFIG_SYS_I2C_SPEED=400000
# CONFIG_MMC is not set
CONFIG_MTD=y
CONFIG_DM_MTD=y
CONFIG_MTD_RAW_NAND=y
CONFIG_SYS_NAND_USE_FLASH_BBT=y
CONFIG_NAND_SUNXI_SPL_ECC_SIZE=512
CONFIG_SYS_NAND_BLOCK_SIZE=0x400000
CONFIG_SYS_NAND_PAGE_SIZE=0x4000
CONFIG_SYS_NAND_OOBSIZE=0x680
CONFIG_SYS_NAND_U_BOOT_OFFS_REDUND=0xc00000
CONFIG_UBI_SILENCE_MSG=y
CONFIG_AXP_ALDO3_VOLT=3300
CONFIG_AXP_ALDO4_VOLT=3300
CONFIG_CONS_INDEX=2
CONFIG_USB_EHCI_HCD=y
CONFIG_USB_OHCI_HCD=y
CONFIG_USB_MUSB_GADGET=y
EOF
Build new configured U-Boot:
make uboot-reconfigure
TODO: In U-Boot:
=> ubi part rootfs
=> ubi info
UBI: MTD device name: "rootfs"
UBI: MTD device size: 4088 MiB
UBI: physical eraseblock size: 2097152 bytes (2048 KiB)
UBI: logical eraseblock size: 2064384 bytes
UBI: number of good PEBs: 2036
UBI: number of bad PEBs: 8
UBI: smallest flash I/O unit: 16384
UBI: VID header offset: 16384 (aligned 16384)
UBI: data offset: 32768
UBI: max. allowed volumes: 128
UBI: wear-leveling threshold: 4096
UBI: number of internal volumes: 1
UBI: number of user volumes: 1
UBI: available PEBs: 122
UBI: total number of reserved PEBs: 1914
UBI: number of PEBs reserved for bad PEB handling: 72
UBI: max/mean erase counter: 2/1
=> ubi info l
Volume information dump:
vol_id 0
reserved_pebs 1838
alignment 1
data_pad 0
vol_type 3
name_len 6
usable_leb_size 2064384
used_ebs 1838
used_bytes 3794337792
last_eb_bytes 2064384
corrupted 0
upd_marker 0
skip_check 0
name rootfs
Volume information dump:
vol_id 2147479551
reserved_pebs 2
alignment 1
data_pad 0
vol_type 3
name_len 13
usable_leb_size 2064384
used_ebs 2
used_bytes 4128768
last_eb_bytes 2
corrupted 0
upd_marker 0
skip_check 0
name layout volume
=> ubifsmount ubi0:rootfs
=> ubifsls /
<DIR> 5024 Thu Jan 01 00:04:02 1970 bin
<DIR> 608 Thu Jan 01 00:04:05 1970 dev
<DIR> 1712 Thu Jan 01 00:04:05 1970 etc
<DIR> 3080 Thu Jan 01 00:04:04 1970 lib
<DIR> 160 Mon Nov 28 09:21:16 2022 mnt
<DIR> 160 Mon Nov 28 09:21:16 2022 opt
<DIR> 160 Sat Dec 03 16:39:02 2022 run
<DIR> 160 Mon Nov 28 09:21:16 2022 tmp
<DIR> 160 Mon Nov 28 09:21:16 2022 sys
<DIR> 672 Thu Jan 01 00:04:05 1970 var
<DIR> 544 Thu Jan 01 00:04:05 1970 usr
<DIR> 304 Thu Jan 01 00:04:02 1970 boot
<DIR> 160 Mon Nov 28 09:21:16 2022 proc
<DIR> 3736 Thu Jan 01 00:04:05 1970 sbin
<DIR> 160 Mon Nov 28 09:21:16 2022 root
<LNK> 11 Thu Jan 01 00:04:04 1970 linuxrc
<LNK> 3 Thu Jan 01 00:04:04 1970 lib32
<DIR> 160 Mon Nov 28 09:21:16 2022 media
=> ubifsls /boot
25748 Thu Dec 01 08:52:19 2022 sun5i-r8-chip.dtb
5357864 Thu Dec 01 08:52:19 2022 zImage
=> ubifsload 0x42000000 /boot/zImage
Loading file '/boot/zImage' to addr 0x42000000...
Done
=> ubifsload 0x43000000 /boot/sun5i-r8-chip.dtb
Loading file '/boot/sun5i-r8-chip.dtb' to addr 0x43000000...
Done
setenv bootargs root=ubi0_0 rootfstype=ubifs ubi.mtd=4 rw earlyprintk waitroot
bootz 0x42000000 - 0x43000000
NOTE: for some reason setenv bootargs root=/dev/ubi0:rootfs rootfstype=ubifs ubi.mtd=4 rw earlyprintk waitroot
does not work. That's why we specify root=ubi0_0.