I've published my u-boot fork here , it contains support for rx1950 and h1940 (there was report that h1940 version works, but I didn't test it by myself). You can build and test them from haret - only usb device and nand work for now, but sd/mmc should work aswell, just need some testing :)) Later this week I'll try to flash u-boot to h1940, just need to solder jtag to its board :)
I've just got u-boot working on rx1950 :) It was launched from haret, however I tested it with jtag - it works aswell if I replace 2nd stage bl in memory with u-boot. I'll publish code as soon as I get time to cleanup it a bit :) P.S. Got another h1940 with broken screen to hack on u-boot for h1940 :)