t1040 IFC flash driver Extended Chip Select

Scott Wood scott.wood at nxp.com
Thu Jul 7 10:57:13 AEST 2016

On 07/06/2016 03:23 PM, Daniel Walker wrote:
> Hi,
> We are using the t1040 platform, and we have found that we need to 
> populate this register. In the Technical Reference Manual it's 
> description is section 24.3.2. This option appears in the driver, but it 
> doesn't appears to be used anyplace.

I'm not sure what you mean by "in the driver".  U-boot sets these registers.

> We we're considered adding something to the device tree to allow 
> populating this value, but I'm wondering if any of you have specific 
> considerations on how this is done. Or maybe it's not needed at all, and 
> we're just missing something.
> (not a good patch, just an example.)
> diff --git 
> a/Documentation/devicetree/bindings/memory-controllers/fsl/ifc.txt 
> b/Documentation/devicetree/bindings/memory-controllers/fsl/ifc.txt
> index 89427b0..b506001 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/fsl/ifc.txt
> +++ b/Documentation/devicetree/bindings/memory-controllers/fsl/ifc.txt
> @@ -24,6 +24,8 @@ Properties:
>   - ranges : Each range corresponds to a single chipselect, and covers
>              the entire access window as configured.
> +- cspr_ext : This value sets the extended chip select for all banks.

I see no reason to put this here.  Boot software should be setting the
chipselect registers, and if for some reason you don't want to do that,
you could just translate the address through ranges to find the value to
write.  Why would you have the binding assume it's the same for all banks?

The information that is missing from the device tree, that currently
must come from boot software programming the registers, is the various
attributes that get programmed in CSPR/CSOR.


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