understanding an IO question

[Ami Levi Waves]

The way we do it:

Fisrt open a memory device:

	Handle = open("/dev/mem", O_RDWR);

Than map the address using:

	mmap(NULL, nAdress, PORT_READ | PROT_WRITE, MAP_SHARED, Handle, your
base address);

mmap returns a virtual pointer, pointing to your HW.

Ami

> -----Original Message-----
> From: linuxppc-embedded-bounces+ami=waves.com at ozlabs.org [mailto:linuxppc-
> embedded-bounces+ami=waves.com at ozlabs.org] On Behalf Of Charles Krinke
> Sent: Wednesday, February 21, 2007 2:14 AM
> To: linuxppc-embedded at ozlabs.org
> Subject: understanding an IO question
> 
> I have a board using an 8541 which is based on the mpc85xx_cds bsp. It
> has one PCI device connected to the 8541, an ASIC we make that maps in
> resources for its registers at 0x8400_0000 - 0x8400_0038.
> 
> The driver for our ASIC works in an 8241 design and I am trying to get
> its register access working in the 8541 and need a little additional
> understanding.
> 
> I can see in cat /proc/iomem where we have memory apparently allocated
> for our registers, like this.
> 
> cat /proc/iomem
> 80000000-9fffffff : PCI1 host bridge
>   84000000-84000038 : ichar
>   88000000-8fffffff : ichar
> e0003000-e00030ff : fsl-i2c.1
> e0004500-e0004507 : serial
> 
> In our driver, I do an ioremap_nocache with 0x8400_0000 as an argument
> to the ioremap and am returned a virtual address of the form
> 0xc905_8000. Unfortunately, I cannot seem to access my registers as they
> all return zero when accessed with the iowrite32/ioread32 helper
> functions.
> 
> A little further. We do use the Outbound Address Translation window
> feature in the 8541 to get to our PCI device and I do set this up in
> uboot and I can read and write registers on our ASIC from uboot. Its
> just in the Linux driver that I seem to be having trouble.
> 
> So,... I am hoping someone could give me a couple of pointers on where
> to look next for the missing piece of why I cannot access the registers
> on our ASIC from Linux whereas things were working fine from uboot
> before booting Linux.
> 
> Charles
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