From 7629a9f661f72eb383fb896e59efea1eac74e882 Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Fri, 26 Oct 2012 18:42:08 +0100
Subject: [PATCH] ARM: 7567/1: io: avoid GCC's offsettable addressing modes for
 halfword accesses

Using the 'o' memory constraint in inline assembly can result in GCC
generating invalid immediate offsets for memory access instructions with
reduced addressing capabilities (i.e. smaller than 12-bit immediate
offsets):

  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54983

As there is no constraint to specify the exact addressing mode we need,
fallback to using 'Q' exclusively for halfword I/O accesses. This may
emit an additional add instruction (using an extra register) in order
to construct the address but it will always be accepted by GAS.

Reported-by: Bastian Hecht <hechtb@googlemail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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