Accessing DDR DCR registers in init_mem - PMC RM9000

Accessing DDR DCR registers in init_mem - PMC RM9000

[Sean Parker]

Hello - 

  We're trying to determine dynamically the DDR DCR register values from within setup.c, init_mem(), so that we can remove the hard-coded 256MB RAM size (and not rely on cmd-line args) From documentation I've read (not evry clear for a MIPS newbie) it appears I need to setup a TLB entry to access phys mem above 0x80000000. (PMON already sets up a range for Compact Flash)

  I setup a TLB entry for that region ( 0xFF080000, making 3 total entries setup in PMON) but I still get an exception in setup.c when I try to read the DCR reg.

  Is it as simple as setting up a TLB entry? I can't find examples for how to access registeres in various segments of physical memory (in kernel mode) does anyone know of a good resource for that kind of stuff?

  Any suggestions?

  Thanks
    Sean



      

Accessing DDR DCR registers in init_mem - PMC RM9000

[Sean Parker]

 Hello - 
 
   We're trying to determine dynamically the DDR DCR
 register values from within setup.c, init_mem(), so that we
 can remove the hard-coded 256MB RAM size (and not rely on
 cmd-line args) From documentation I've read (not evry
 clear for a MIPS newbie) it appears I need to setup a TLB
 entry to access phys mem above 0x80000000. (PMON already
 sets up a range for Compact Flash)
 
   I setup a TLB entry for that region ( 0xFF080000, making
 3 total entries setup in PMON) but I still get an exception
 in setup.c when I try to read the DCR reg.
 
   Is it as simple as setting up a TLB entry? I can't
 find examples for how to access registeres in various
 segments of physical memory (in kernel mode) does anyone
 know of a good resource for that kind of stuff?
 
   Any suggestions?
 
   Thanks
    Sean