Re: I/O mapping on IXP425

[Deepak Saxena <dsaxena@xxxxxxxxxxx>]

On Apr 05 2005, at 14:47, Nestor was caught saying:
> 
> Hi,
> 
> I'm working with IXP425 and ARM-Linux (2.4.24-uc0) and have some questions on I/O mapping for this processor.
> 
> The file "snapgear-3.1.1/linux-2.4.x/include/asm/arch-ixp425/ixp425.h" has the following lines:
> 
> * 0x50000000	0x10000000	Not Mapped	EXP BUS
> (...)
> #define IXP425_EXP_BUS_BASE2_PHYS	(0x50000000)
> #define IXP425_EXP_BUS_BASE2_VIRT	(0xF0000000)
> 
> The 2.6 version of this file ("snapgear-3.1.1/linux-2.6.x/include/asm/arch-ixp425/ixp425.h") has the following lines:
> 
>  * 0x50000000	 0x10000000	ioremap'd	EXP BUS
> (...)
> #define IXP425_EXP_BUS_BASE2_PHYS	(0x50000000)
> #define IXP425_EXP_BUS_BASE2_VIRT	(0xF0000000)
> 
> Q1) what is the correct comment?

The 2.6 version, theough the BASE2_VIRT entry needs to go away as
we don't static-map the expansion bus region.

> Q2) what is the virtual address that corresponds to physical address 0x53000000?

You need to ioremap(), so there's no set virtual address.

> Q3) can I use a fixed address to reach the physical address 0x53000000 instead of using ioremap_nocache?

If you static map by adding an entry to arch/arm/mach-ixp4xx/common.c or
to your machine-specific code, but I don't recommend that.

~Deepak

-- 
Deepak Saxena - dsaxena@xxxxxxxxxxx - http://www.plexity.net

Even a stopped clock gives the right time twice a day.

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