Re: MPC82xx -- DPRAM1

I am not sure if I understand you. The CPM must have been told somehow 
that there is something for its peripherals in this particular region of 
the dpram1 or no ? I wild guess could be that the bootloader (in this case 
u-boot) has configured this area of dpram1 behind the back of the kernel. 
I assume that is not the case. Would not that be rather ugly ?
 
The mcc driver I am trying to get running on linux-2.6.9 is a driver I 
wrote for pSos a few years ago, and it is running fine on that platform.
Therefore, I am sure that there is nothing i the processor or the cpm that 
prevents me from putting mcc related parameters at offset zero in the 
dpram1.
I am still trying to figure out what piece of code in the kernel that I 
have to manipulate to get this driver working. 

Thanks for any advise,
Morten





"Mark Chambers" [off-list ref]
16.11.2004 04:43

 
        To:     [off-list ref]
        cc: 
        Subject:        Re: MPC82xx -- DPRAM1


The thing you might be missing is that the CPM coprocessor uses some dpram
that
is not accessed by the PPC processor at all.  So the memory must be set
aside for
the peripherals but the linux code won't reference it.

Mark Chambers

----- Original Message ----- 
From: "Dan Malek" <redacted>
To: <redacted>
Cc: <redacted>
Sent: Monday, November 15, 2004 7:18 PM
Subject: Re: MPC82xx -- DPRAM1

On Nov 15, 2004, at 11:10 AM, morten.banzon@axxessit.no wrote:

quoted

I am using 2.6.9 for a mpc8280 project, and am having trouble using
dpram1
from offset zero, which I need for a mcc hdlc driver.

Why does it have to start at zero?

quoted

 In the file include/asm-ppc/cpm2.h there is a constant
CPM_DATAONLY_BASE
In the same file the code comment say that the first 128 bytes are 

used

quoted

for SMC1 and SMC2.

Yes, it is.

quoted

When I examine the smc (cpm_uart) driver i do not find any reference 

to

quoted

this region of the dpram1.

It's there somewhere, hardcoded with values 0, then sizeof() something
is
probably added to it.

quoted

I have replaced the calls to cpm_dpalloc with cpm_dpalloc_fixed and an
adress way up in the dpram1 region.

Very bad idea.

quoted

My question is; do you know which code is using the dpram1 addresses
below
CPM_DATAONLY_BASE ?

The SMC1 and SMC2 peripherals, just like the comment says.

quoted

This region must be used by something (smc ?), because when I clear
from
offset 0x00 to 0x80 the serial port stop responding.

Yep.


-- Dan

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