From: David Daney <ddaney@caviumnetworks.com>
To: Ed Okerson <ed.okerson@gmail.com>
Cc: linux-mips@linux-mips.org
Subject: Re: mmap KSEG1
Date: Fri, 04 Dec 2009 10:12:18 -0800 [thread overview]
Message-ID: <4B195102.1020606@caviumnetworks.com> (raw)
In-Reply-To: <83f0348b0912040952h40d4d151n79ca5fc33a830ee2@mail.gmail.com>
Ed Okerson wrote:
> Is it possible to mmap an address in KSEG1 so a user space app can
> read/write to an IO device uncached?
>
It depends on your definition of 'possible'. The mips32/64 architecture
specification has a 'C' field in the EntryLo register that controls
cachability, so given an appropriate device driver it should be doable.
Calling __ioremap() with the appropriate flags should allow you to set
the 'C' bits.
Depending on your requirements, you might be able to get by using
/dev/mem and some 'sync' instructions, instead of establishing an
uncached mapping.
David Daney
next prev parent reply other threads:[~2009-12-04 18:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-04 17:52 mmap KSEG1 Ed Okerson
2009-12-04 18:12 ` David Daney [this message]
2009-12-04 18:33 ` Thomas Bogendoerfer
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