Hi Siarhei,
On 5 February 2015 at 02:36, Siarhei Siamashka siarhei.siamashka@gmail.com wrote:
!!! Works only on Allwinner A20 so far and needs a bit more !!! debugging. And even on A20, the transition from the SPL to !!! the main U-boot binary has some glitches.
Now it should be possible to load and execute the same U-Boot SPL, as used for booting from SD cards. The only argument for this new command is the name of the SPL binary file (with eGON header). It can be run as:
fel spl u-boot-sunxi-with-spl.bin
This looks great! Does it write only the SPL portion or does it write U-Boot also?
I don't really understand how it works but will leave that to you and Hans.
The free space in SRAM is scattered in the FEL mode across multiple locations. We just split SPL into individual chunks, upload them to the free locations in SRAM and also upload a small startup code, which is responsible for harvesting and gluing the pieces of SPL together. Additionally, the eGON checksum is verified to ensure that no data corruption has happened due to some unexpected clash with the FEL protocol code from the BROM.
After this is done, it is not possible to return back to FEL anymore (both IRQ and normal stacks of the BROM are overwritten). However it is still possible to transfer control to the FEL init code (so that it re-initializes the USB hardware and all the other things):
/* Jump to the FEL entry point in BROM */ movw r0, #0x20 movt r0, #0xffff bx r0This unifies the FEL and SD card SPL binaries. And also removes the FEL SPL size limit (now it can be as large as ~30 KiB).
This work had been inspired by the recent FEL mode support u-boot patches from Simon Glass and Hans de Goede.
Signed-off-by: Siarhei Siamashka siarhei.siamashka@gmail.com
[snip]
Regards, Simon