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[[!meta title="NetBSD/evbarm on Hardkernel ODROID-C1 and ODROID-C1+"]]

[ODROID-C1](https://www.hardkernel.com/shop/odroid-c1-2/) was a $35 quad-core SBC from Hardkernel. ODROID-C1 support was introduced in NetBSD 7.0.  It has been succeeded by the [ODROID-C1+](https://www.hardkernel.com/shop/odroid-c1/), which is supported by the same NetBSD kernel.

[[!toc levels=2]]

# Supported hardware
 - CPU: Cortex-A5: Amlogic S805 (4-core) at 1.5GHz
   - CPU frequency scaling is supported with machdep.cpu sysctl tree
   - SMP supported
   - PL310 L2 cache controller
 - GIC
 - A5 global timer
 - Watchdog timer
 - "SDHC" and "SDIO" SD/MMC controllers (DMA)
 - Serial console
 - Framebuffer console
 - USB host (OTG)
 - Gigabit Ethernet (GMAC)
   - RTL8211F PHY
 - Hardware random number generator
 - RTC
 - GPIO

# TODO
 - USB device mode
 - IR receiver
 - I2C
 - Audio

# Installation (NetBSD 8.0 and later)

* Start with an ARMv7 image from *evbarm-earmv7hf/binary/gzimg/* such as *armv7.img*, the latest is [[here|https://nycdn.netbsd.org/pub/NetBSD-daily/HEAD/latest/evbarm-earmv7hf/binary/gzimg/armv7.img]].
* Build U-Boot for ODROID-C1 <https://github.com/jaredmcneill/u-boot-odroid>
  * Pre-built binaries here:
   <http://ftp.netbsd.org/pub/NetBSD/misc/jmcneill/odroidc1/u-boot-odroidc-v2011.03-20150308.tar.gz>
   <http://www.netbsd.org/~jmcneill/u-boot.bin.odroidc1>
* Write the bootloader to the empty space at the start of the base image:
[[!template  id=programlisting text="""
# dd if=bl1.bin.hardkernel of=armv7.img bs=1 count=442 conv=notrunc
# dd if=bl1.bin.hardkernel of=armv7.img bs=512 skip=1 seek=1 conv=notrunc
# dd if=u-boot.bin.odroidc1 of=armv7.img bs=512 seek=64 conv=notrunc
"""]]
* Write the image to an SD card.

- Tested 2021-02-19 with NetBSD-current, christos
  - serial fights with ucb keyboard. (avoid by short circuiting cngetc in meson_uart.c to return -1)
  - awge0 does not work reliably (can't even get a dhcp address, stops receiving packets after less than a minute)
  - machine crashes under load

# Installation (NetBSD 7.0/7.1)

* Start with an ARMv7 image from *evbarm-earmv7hf/binary/gzimg/* such as *armv7.img*
* Build U-Boot for ODROID-C1 <https://github.com/hardkernel/u-boot/tree/odroidc-v2011.03>
  * Pre-built binaries here: <http://ftp.netbsd.org/pub/NetBSD/misc/jmcneill/odroidc1/u-boot-odroidc-v2011.03-20150308.tar.gz>
* Note the location and size of the FFS partition in the *armv7.img* disklabel:
[[!template  id=programlisting text="""
# $TOOLDIR/bin/nbdisklabel -M evbarm -B le armv7.img
...
8 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:   1359312    385024     4.2BSD      0     0     0  # (Cyl.    188 -    851*)
 b:    262144    122880       swap                     # (Cyl.     60 -    187)
 c:   1744336         0     unused      0     0        # (Cyl.      0 -    851*)
 d:   1744336         0     unused      0     0        # (Cyl.      0 -    851*)
 e:    114688      8192      MSDOS                     # (Cyl.      4 -     59)
"""]]
* Write the bootloader to the empty space at the start of the base image:
[[!template  id=programlisting text="""
# dd if=bl1.bin.hardkernel of=armv7.img bs=1 count=442 conv=notrunc
# dd if=bl1.bin.hardkernel of=armv7.img bs=512 skip=1 seek=1 conv=notrunc
# dd if=u-boot.bin of=armv7.img bs=512 seek=64 conv=notrunc
"""]]
* Since the bootloader has overwritten the disklabel, we need to re-add partition "a" from the disklabel to the MBR partition table:
[[!template  id=programlisting text="""
# $TOOLDIR/bin/armv7--netbsdelf-eabihf-fdisk -u armv7.img
...
Which partition do you want to change?: [none] 1
The data for partition 1 is:
<UNUSED>
sysid: [0..255 default: 169] 
start: [0..109cyl default: 63, 0cyl, 0MB] 385024
size: [0..85cyl default: 1359312, 85cyl, 664MB] 1359312
...
Which partition do you want to change?: [none] 
...
Should we write new partition table? [n] y
"""]]
* Write the image to an SD card.
* Edit *boot.ini* on the MS-DOS partition. Note that the default boot.ini has `console=fb` in `bootargs`, which you should remove if you want serial console:
[[!template  id=programlisting text="""
ODROIDC-UBOOT-CONFIG

setenv bootargs "root=ld0f awge0.mac-address=${ethaddr} console=fb"
setenv bootcmd "fatload mmc 0:1 0x21000000 netbsd.ub; bootm 0x21000000"
run bootcmd
"""]] 

* On first boot, it will stop because of the wrong device in /etc/fstab. Take this opportunity to grow the root file-system:
[[!template  id=programlisting text="""
# fdisk -u ld0
...
Which partition do you want to change?: [none] 1
The data for partition 1 is:
NetBSD (sysid 169)
    start 385024, size 1359312 (664 MB, Cyls 23/246/32-108/147/55)
        PBR is not bootable: All bytes are identical (0x00)
sysid: [0..255 default: 169]
start: [0..966cyl default: 385024, 24cyl, 188MB]
size: [0..942cyl default: 1359312, 85cyl, 664MB] $
...
Which partition do you want to change?: [none]
...
Should we write new partition table? [n] y
# resize_ffs -y /dev/rld0f
# reboot
"""]]
* Next boot, create a new /etc/fstab:
[[!template  id=programlisting text="""
# mount -u -o rw /dev/ld0f /
# cat > /etc/fstab << EOF
/dev/ld0f       /               ffs     rw      1 1
/dev/ld0e       /boot           msdos   rw      1 1
kernfs          /kern           kernfs  rw
ptyfs           /dev/pts        ptyfs   rw
procfs          /proc           procfs  rw
tmpfs           /var/shm        tmpfs   rw,-m1777,-sram%25
EOF
# reboot
"""]]

# HDMI

## Framebuffer console

Simply add **console=fb** to the *bootargs* variable in *boot.ini*.

## Video mode

HDMI video mode can be selected in U-Boot with the *video* command, e.g.:

[[!template  id=programlisting text="""
odroidc#video dev open 1080P
"""]]

To make this change permanent, add it to the *bootcmd* variable in *boot.ini*:

[[!template  id=programlisting text="""
setenv bootcmd "video dev open 1080P; fatload mmc 0:1 0x21000000 netbsd.ub; bootm 0x21000000"
"""]]

## 16 or 24 bpp?

ODROID-C1 defaults to 16bpp. If you want to try 24bpp, add **fb.depth=24** to the kernel cmdline options in *boot.ini*. There are some issues with 24bpp mode and Xorg; see <http://gnats.netbsd.org/49812>.

## Overscan compensation

If you have ODROID-C1 plugged into a TV, the edges of the screen may not be visible. You can scale down the framebuffer console with the **hw.genfb0.scale** sysctl, e.g.:

[[!template  id=programlisting text="""
# sysctl -w hw.genfb0.scale=95
"""]]

Setting *scale* to 100 disables scaling, any other value enables the scaler. Values between 10 and 100 are allowed.

To set this value at boot, you can add **fb.scale=95** to the kernel cmdline options in *boot.ini*.

# SYS_LED

The blue SYS_LED on the board is wired to GPIOAO_13. To control the LED from userland, set **gpio=YES** in rc.conf and add this to */etc/gpio.conf*:

[[!template  id=programlisting text="""
gpio4 13 set out sys_led
"""]]

After rebooting, the LED state can be controlled with [[!template id=man name="gpioctl" section="8"]].

[[!template  id=programlisting text="""
# turn the light on
gpioctl gpio4 sys_led on

# turn the light off
gpioctl gpio4 sys_led off

# toggle the light state
gpioctl gpio4 sys_led toggle
"""]]

# U-Boot Environment

To read/write U-Boot environment variables from NetBSD, download and compile the following program: <http://ftp.netbsd.org/pub/NetBSD/misc/jmcneill/odroidc1/uenv.c>

# Automatically booting a backup kernel

*These instructions assume the kernels live on eMMC. Adjust devices accordingly for SD card setup.*

To setup an ODROID-C1 to fall back to a recovery kernel in the event of a boot failure, install the recovery kernel as /boot/onetbsd.ub.

Create /boot/boot.ini as follows:
[[!template  id=programlisting text="""
ODROIDC-UBOOT-CONFIG
setenv bootargs "root=ld0f awge0.mac-address=${ethaddr}"
fatload mmc 0:1 0x22000000 boot.scr
source 0x22000000
"""]]

Create /boot/boot.txt:
[[!template  id=programlisting text="""
# regenerate with:
#  mkubootimage -A arm -C none -O netbsd -T script -a 0 -n "NetBSD/odroidc1 boot" boot.txt boot.scr

setenv rescue_kernel "onetbsd.ub"
setenv kernel "netbsd.ub"

if test ${boot_rescue} = false; then
  setenv boot_rescue true
  saveenv
  fatload mmc 0:1 0x21000000 ${kernel}
  mw.l c1109900 0f08ffff        # arm watchdog
  bootm 0x21000000
else
  fatload mmc 0:1 0x21000000 ${rescue_kernel}
  bootm 0x21000000
fi
"""]]

Generate boot.scr from boot.txt:
[[!template  id=programlisting text="""
mkubootimage -A arm -C none -O netbsd -T script -a 0 -n "NetBSD/odroidc1 boot" /boot/boot.txt /boot/boot.scr
"""]]

Install the **uenv** tool from above and add the following to root's crontab:
[[!template  id=programlisting text="""
@reboot                                 /usr/local/sbin/uenv ld0 boot_rescue false
"""]]

# Documentation

Amlogic S805 datasheet: <http://dn.odroid.com/S805/Datasheet/S805_Datasheet%20V0.8%2020150126.pdf>

# ODROID-C1 UART pins

From [ODROID Forum](http://forum.odroid.com/viewtopic.php?f=115&t=7684):

[[!template  id=programlisting text="""
 ___UART____
|Pin 4 - GND|
|Pin 3 - RXD|
|Pin 2 - TXD|
|Pin 1 - VCC|
\___________|

3.3V LVTTL
"""]]