Re: HELP:(VIPER BOARD)AC'97 controller driver for rtlinux(rtlinux core driver)

[nitin ahuja]

Hi,

>
> I am trying to develop a codec driver (rtlinux 
> driver) from scratch. In Viper board (PXA255) 
> physical memory range 0x40000000-0x43FFFFFF is used 
> by the PXA255 peripherals.In that address range
> 0x40500000-0x405005FC is needed for AC'97 controller
> registers. Is this memory range is already mapped to
> virtual address space, else How to map this to 
> virtual address space.
>

You have to map this address range using "ioremap()". Data at address returned by ioremap can be accessed by calling readl(), writel() et al

>
> When i tried ioremap() it is giving same virtual
> address with different physical address(i tried
> ioremap with another driver(same board)with different
> physical memory address)
>

Same virtual address can point to different physical addresses depending upon how it is mapped.

Nitin

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