Justin Swartz

justin.swartz @ risingedge.co.za

Consulting Services

Appropriate Technology Selection
Data Recovery (eMMC, NAND & NOR Flash, SD)
Debugging, Fault Finding and Troubleshooting
Embedded System Integration
Network Configuration
Reverse Engineering
Software Development
System Administration
Vulnerability Assessment

Tools

ias - a poor man's machine code generator
iix - run a command with files/FIFOs attached to stdin
ipconfigstore - an Android ipconfig manipulator
leer - monitor a process's calls to write(2)
mle - write machine code with labels and macros.
mli - run machine code executables without an object file format.
mlx - run machine code without an object file format.
monitor-test - a bootable colour test tool for eWaste'd monitors
sdmmc/spi - interact with SD/MMC cards over SPI
shelf - shell scripts that spawn ELF objects without a linker
xfasm - an 8086/186/286 assembler in POSIX shell script
xfbl - a Linux/x86 floppy bootloader (in 512 bytes)
xfl-brfw - a Linux/x86 bridging firewall on a floppy

Notes

Bookmarklets

Open Source Contributions

Linux

Added a missing CPU clock rate for RK322x SoCs.

Patched the Rockchip DRM driver to allow use of the Synopsis DesignWare HDMI transmitter and an Innosilicon HDMI PHY present in RK322x SoCs.

Grafted a few display related and 2D graphic accelerator nodes declarations to the RK322x SoC device tree.

Planted a device tree for the Mecer Xtreme Mini S6 and its WLAN module.

Fixed incorrect GPU clock configuration (without access to the Technical Reference Manual!) for RK322x based targets.

Hung two missing serial ports on the MT7621 SoC device tree, and reordered it according to the DTS style guide.

Found a bug in the MT7530 Ethernet Switch driver where an incorrect external crystal frequency may be selected under certain conditions.

Patched the MT7621 SPI driver to allow the use of GPIO as Chip Select lines.

netfilter
- I wanted to link ebtables as a static binary.

U-Boot
- Fixed an obviously incorrect DRAM size calculation for Rockchip targets that make use of OP-TEE. The patch was disregarded, though a patch from someone else with similar intent was accepted and applied a few months later.

Client Feedback

"We reached out to Justin to assist in a data recovery job on a high end fish finder unit. The end customer had waypoints saved which were extremely important to them. After days of attempting to recover the data we reached out to Justin. He was able to successfully carve out the proprietary data from a memory chip dump in what seemed like no time at all. His skill and speed with embedded systems is remarkable. Justin is our go-to-guy for any complex embedded task! Thanks Justin!!" Chad Rudolph Rudolph Electronic Repair www.rudolphrepairs.com

"Freelancer has deep experience with operating systems and systems administration. He was able to implement various functionalities in NixOs that worked out of the box. We hope to work with him again in future!" Johannes Tynes Tynes Science www.tynes.science

"Justin is very experienced and considerate. I highly recommend him to any client looking for great code and a fast turnaround. If you need an absolute expert in C programming, you must work with Justin! He has extensive knowledge in this space" Sabrina Gouveia Petit Bamboo Digital

"Amazing work from Justin on my project. He dedicated time and energy to make it a success! I highly recommend him." Guillaume Charhon Smart Mobile Software www.smartmobilesoftware.com

"Justin has been great to work with and has been super patient with my frequent requests. He really knows his stuff and if he isn't familiar with something goes beyond what is needed to figure out a solution to help! He is great at what he does and I can't recommend him enough!" David Blaney Qubestake www.qubestake.io