30 Oct
2010
30 Oct
'10
2:53 p.m.
Hi Marcin,
On 30.10.2010 13:51, Marcin Mielczarczyk wrote:
In this case, first I'll explain how it works.
Nomenclature:
1) internal bootloader - bootloader placed at 0x48000000 in System ROM
2) 2nd stage bootloader or extarnal bootloader - bootloader placed in
NAND - initializes DRAM controller and boots MTK's software - this
bootloader prints info on UART by default
When MT6235 processor starts it has RM1 bit disabled in EMI_GENA
register (External Memory Interface controller),
which forces ARM926 core to jump first to System ROM (0x48000000).
When internal bootloader is executed it initializes UART to 19200n8
and checks if specific character is received.
Alright, this is how it works on the MT622x as well.
This is source code where you can build your own
Download Agent. This
is how I first executed my own code on MT6235. It has all make files
and it's prepared for ADS compiler.
When you'll build your own Download Agent you just select this file in
FlashTool and you have your code executed in RAM.
I saw that you can use it on all MTK platforms.
FlashTool links are also available on pudn.com
I didn't analyze this path of bootloader, but it could be good to have
it if we would like to create our own flashing tool under Linux (i.e.
for flashing U-Boot).
That's pretty interesting, since it could be used to create
authentificated code for other phones with the secure romloader, too.
> This is great. So far, we have not seen any
MT622x based phone that has
> JTAG exposed. Even the Huayu development modules for the MT622x don't have
> it.
Well, there is the CECT C3100 which has JTAG solder pads. OpenOCD
successfully detected the CPU, but I couldn't halt the ARM core (same
problem on the Calypso btw). I tried other random ARM7 targets which had
the same EmbeddedICE revision and there it worked.
Yes, I agree.
In this case to download U-Boot to NAND we can use FlashTool (only for Windows).
Then as you stated we can use U-Boot to load code from SD/MMC/serial.
Getting osmocon to work with the secure romloader could be an option as
well. Currently it only supports the non-secure romloader without that
*.auth and SLA_Challenge.dll stuff.
Plus we have a CFI-flash driver for the Compal phones, which might work
on the MTK platform with a few modifications. If that works, we could
flash U-Boot without any proprietary Flashtool/DownloadAgent.
Regards,
Steve