From: Stefan Roese <sr@denx.de>
To: linuxppc-embedded@ozlabs.org
Subject: Re: Yosemite/440EP why are readl()/ioread32() setup to read little-endian?
Date: Wed, 25 Jan 2006 10:57:47 +0100 [thread overview]
Message-ID: <200601251057.47619.sr@denx.de> (raw)
In-Reply-To: <43D66D06.9090904@ovro.caltech.edu>
Hi David,
On Tuesday 24 January 2006 19:08, David Hawkins wrote:
> readl() and ioread32() read the registers in little-endian format!
Correct. That's how it is implemented on all platforms. Think for example of
an pci device driver. Using these IO functions, the driver will become
platform independent, running without modifications on little- and big-endian
machines.
> If the processor was reading from the PCI bus, then sure, I
> could understand why this might be used, but even then, that
> should be up to the user, eg. by using cpu_to_le32 etc.
No. Please see above.
> Should I just be using pointers for remapped processor
> registers, and only use readl(), ioread32(), etc, on external
> memory?
That's how I do it. Only use readl() and friends for pci spaces (or other
little endian memory mapped areas).
Best regards,
Stefan
next prev parent reply other threads:[~2006-01-25 9:58 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-17 0:45 [Patch 3/3] Add Yellowstone Platform defconfig John Otken
2006-01-24 18:08 ` Yosemite/440EP why are readl()/ioread32() setup to read little-endian? David Hawkins
2006-01-24 19:07 ` Yosemite/440EP is there a global interrupt enable mask? David Hawkins
2006-01-25 10:28 ` Stefan Roese
2006-01-25 18:30 ` David Hawkins
2006-01-25 18:55 ` Eugene Surovegin
2006-01-25 19:46 ` David Hawkins
2006-01-25 20:13 ` Eugene Surovegin
2006-01-25 20:34 ` David Hawkins
2006-01-25 9:57 ` Stefan Roese [this message]
2006-01-25 18:26 ` Yosemite/440EP why are readl()/ioread32() setup to read little-endian? David Hawkins
2006-01-25 18:51 ` Eugene Surovegin
2006-01-25 19:36 ` David Hawkins
2006-01-25 19:48 ` Eugene Surovegin
2006-01-26 10:20 ` Stefan Roese
2006-01-27 0:10 ` David Hawkins
2006-01-27 23:29 ` David Hawkins
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