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List:       openocd-development
Subject:    [OpenOCD-devel] ARM940T / S3C2510A01 support?
From:       Uwe Hermann <uwe () hermann-uwe ! de>
Date:       2012-04-30 15:07:01
Message-ID: 20120430150701.GA23197 () greenwood
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Hi,

I've opened a Linksys BEFVP41 router recently and attached a JTAG
interface to the Samsung S3C2510A01 in the device.

  http://www.randomprojects.org/wiki/Linksys_BEFVP41

I'm not so sure how far the OpenOCD support for ARM940T and S3C2510A01
specifically is, though. Can this work reliably? Which parts would work,
and what would not work?

I made a test .cfg file for now using arm920t or arm9tdmi, but that's not
really technically correct. Using "-variant arm940t" is also useless, as
far as I can see unknown variants are ignored, i.e. I could also write
"-variant foo" with the same effect, right?


  if { [info exists CHIPNAME] } {
     set _CHIPNAME $CHIPNAME
  } else {
     set _CHIPNAME s3c2510a
  }
  
  if { [info exists ENDIAN] } {
     set _ENDIAN $ENDIAN
  } else {
     set _ENDIAN little
  }
  
  if { [info exists CPUTAPID] } {
     set _CPUTAPID $CPUTAPID
  } else {
     set _CPUTAPID 0x1094009d
  }
  
  jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0x0f -expected-id $_CPUTAPID
  
  set _TARGETNAME $_CHIPNAME.cpu
  # TODO: It's an ARM940T really.
  # target create $_TARGETNAME arm920t -endian $_ENDIAN -chain-position $_TARGETNAME -variant arm940t
  target create $_TARGETNAME arm9tdmi -endian $_ENDIAN -chain-position $_TARGETNAME -variant arm940t
  
  # $_TARGETNAME configure -work-area-phys 0x200000 -work-area-size 0x4000 -work-area-backup 1
  $_TARGETNAME configure -work-area-phys 0x40000000 -work-area-size 0x4000 -work-area-backup 1
  
  reset_config trst_and_srst combined
  
  # External Macronix MX29LV800BBTC-90 (NOR flash) chip.
  flash bank $_CHIPNAME.extnorflash cfi 0x00000000 0x100000 2 2 $_TARGETNAME
  
  init
  reset halt
  
  # flash probe 0

I'm able to get some good-looking output with the above config:

  > scan_chain
     TapName             Enabled  IdCode     Expected   IrLen IrCap IrMask
  -- ------------------- -------- ---------- ---------- ----- ----- ------
   0 s3c2510a.cpu           Y     0x1094009d 0x1094009d     4 0x01  0x0f

  > targets
      TargetName         Type       Endian TapName            State       
  --  ------------------ ---------- ------ ------------------ ------------
   0* s3c2510a.cpu       arm920t    little s3c2510a.cpu       halted

  > flash probe 0
  Flash Manufacturer/Device: 0x00c2 0x225b
  flash 'cfi' found at 0x00000000

  > dump_image linksys_befvp41_nor.dd 0x00000000 0x100000
  dumped 1048576 bytes in 46.292549s (22.120 KiB/s)

The dumped NOR contents _seem_ to be non-garbage too, but how can I be
sure that everything really works as expected for ARM940T / S3C2510A01?

I'm a bit reluctant to submit a .cfg file which is potentially broken in
subtle ways I cannot see right now. Does anyone have some insights as to
how far the OpenOCD internals would work for ARM940T, and/or which parts
would need fixing?


Thanks, Uwe.
-- 
http://hermann-uwe.de     | http://sigrok.org
http://randomprojects.org | http://unmaintained-free-software.org

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