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uio: Support physical addresses >32 bits on 32-bit systems

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To support >32-bit physical addresses for UIO_MEM_PHYS type we need to
extend the width of 'addr' in struct uio_mem.  Numerous platforms like
embedded PPC, ARM, and X86 have support for systems with larger physical
address than logical.

Since 'addr' may contain a physical, logical, or virtual address the
easiest solution is to just change the type to 'phys_addr_t' which
should always be greater than or equal to the sizeof(void *) such that
it can properly hold any of the address types.

For physical address we can support up to a 44-bit physical address on a
typical 32-bit system as we utilize remap_pfn_range() for the mapping of
the memory region and pfn's are represnted by shifting the address by
the page size (typically 4k).

Signed-off-by: Kai Jiang <Kai.Jiang@freescale.com>
Signed-off-by: Minghuan Lian <Minghuan.Lian@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Hans J. Koch <hjk@hansjkoch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Kai Jiang
2011-10-17 20:50:20 +02:00
committed by Greg Kroah-Hartman
parent c4253cb074
commit 27a90700a4
3 changed files with 9 additions and 7 deletions
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2
Documentation/DocBook/uio-howto.tmpl
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@ -529,7 +529,7 @@ memory (e.g. allocated with <function>kmalloc()</function>). There's also
</para></listitem>
<listitem><para>
<varname>unsigned long addr</varname>: Required if the mapping is used.
<varname>phys_addr_t addr</varname>: Required if the mapping is used.
Fill in the address of your memory block. This address is the one that
appears in sysfs.
</para></listitem>