Over the last weekend, Stefan, Zecke and myself have been focusing on getting some work done for the gnufiish project. As usual with this kind of reverse engineering project, you never really know how long you need until you've cracked all the major difficulties.
The biggest issue with gnufiish is the lack of working support for the 3.5G modem in the device. Obviously, without such support the device is nothing else but a nice PDA. Disconnected from the rest of the world.
We still don't have a working 3.5G modem under Linux, but we have made the following progress:
- confirmed that the modem is attached over UART in addition to SPI
- learned that the modem uses some kind of binary protocol on the UART at least for firmware updates
- discovered the meaning of quite a number of additional pins on the debug connector, including the serial console. Almost all pins should be known by now.
- a preliminary u-boot port has been produced. It can be loaded via OpenOCD/JTAG and accessed over serial console or USB serial emulation. It doesn't yet have the full feature set as people are used from Openmoko GTA01/GTA02, but NAND and SD card access are working
- ported Werners Linux userspace s3c24xx-gpio tool into u-boot. This makes it much more convenient to play with the GPIO's without computing boolean bit masking operators in your head. And since booting into Linux userspace takes way too long right now, having this in u-boot really is the right thing.
- learned more about the various programs installed in the E-TEN ROM image, i.e. their initial loader, usb downloader as well as the Empire/Knight test environment.
- we discovered some bug in OpenOCD leading to problems with breakpoints, Zecke cooked up a patch for this.
If you're interested in the intermediate results / notes, feel free to check the M800 as well as 3.5G modem related pages in the wiki.