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arch/*/io.h: remove ioremap_uc in some architectures

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ioremap_uc() is only meaningful on old x86-32 systems with the PAT
extension, and on ia64 with its slightly unconventional ioremap()
behavior. So remove the ioremap_uc() definition in architecutures
other than x86 and ia64. These architectures all have asm-generic/io.h
included and will have the default ioremap_uc() definition which
returns NULL.

This changes the existing behaviour, while no need to worry about
any breakage because in the only callsite of ioremap_uc(), code
has been adjusted to eliminate the impact. Please see
atyfb_setup_generic() of drivers/video/fbdev/aty/atyfb_base.c.

If any new invocation of ioremap_uc() need be added, please consider
using ioremap() intead or adding a ARCH specific version if necessary.

Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Helge Deller <deller@gmx.de>  # parisc
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> (SuperH)
Cc: linux-alpha@vger.kernel.org
Cc: linux-hexagon@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Baoquan He
2023-09-21 19:04:23 +08:00
committed by Arnd Bergmann
parent 4bfb53e7d3
commit 026246f114
9 changed files with 5 additions and 16 deletions
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Documentation/driver-api/device-io.rst
+5 -4
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@@ -408,11 +408,12 @@ functions for details on the CPU side of things.
ioremap_uc()
------------
ioremap_uc() behaves like ioremap() except that on the x86 architecture without
'PAT' mode, it marks memory as uncached even when the MTRR has designated
it as cacheable, see Documentation/arch/x86/pat.rst.
ioremap_uc() is only meaningful on old x86-32 systems with the PAT extension,
and on ia64 with its slightly unconventional ioremap() behavior, everywhere
elss ioremap_uc() defaults to return NULL.
Portable drivers should avoid the use of ioremap_uc().
Portable drivers should avoid the use of ioremap_uc(), use ioremap() instead.
ioremap_cache()
---------------