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

This patchset tries to remove ioremap_uc() in the current architectures except of x86 and ia64. They will use the default ioremap_uc version in <asm-generic/io.h> which returns NULL. Anyone who wants to add new invocation of ioremap_uc(), please consider using ioremap() instead or adding a new ARCH specific ioremap_uc(), or refer to the callsite in drivers/video/fbdev/aty/atyfb_base.c.

This change won't cuase breakage to the current kernel because in the only ioremap_uc callsite, an adjustment is made to eliminate impact in patch 1 of this series.

To get rid of all of them other than x86 and ia64, add asm-generic/io.h to asm/io.h of mips ARCH. With this adding, we can get rid of the ioremap_uc() in mips too. This is done in patch 2. And a followup patch 4 is added to remove duplicated code according to Arnd's suggestion.

Test:
=====
Except of Jiaxun's efficient testing on patch 2/4, I also did cross compiling of this series on mips64, building passed.

History:
=======
v4->v5:
- In v4, Thomas reported that adding <asm-generic/io.h> including into mips always cause crash on his malta qemu. Finally, Jiaxun stood up to take over the patch 2/4 and make it work. This patchset collects Jiaxun's patch v5 and add Arnd's tag. Thanks to Jiaxun.
- Meanwhile, the old patch 4/4 need be adjusted because Jiaxun has done some removal of duplicated codes in <asm/io.h>.
- Add reviewers' tags from v4.
v3->v4:
- Add patch 1 to adjust code in the only ioremap_uc() callsite so that later removing ioremap_uc() won't cause breakage.
- Update log and document writing in patch 3.
- Add followup patch 4 to clean up duplicated code in asm/io.h of MIPS.
v2->v3:
- In patch 1, move those macro definition of functio near its function declaration according to Arnd's suggestion. And remove the unneeded change in asm/mmiowb.h introduced in old version.
- In patch 2, clean up and rewrite the messy document related to ioremap_uc() in Documentation/driver-api/device-io.rst.
v1->v2:
- Update log of patch 2, and document related to ioremap_uc() according to Geert's comment.
- Add Geert's Acked-by.

Arnd Bergmann (1):
video: fbdev: atyfb: only use ioremap_uc() on i386 and ia64

Baoquan He (2):
arch/*/io.h: remove ioremap_uc in some architectures
mips: io: remove duplicated codes

Jiaxun Yang (1):
mips: add <asm-generic/io.h> including

 Documentation/driver-api/device-io.rst |   9 +-
 arch/alpha/include/asm/io.h            |   1 -
 arch/hexagon/include/asm/io.h          |   3 -
 arch/m68k/include/asm/kmap.h           |   1 -
 arch/mips/include/asm/io.h             | 123 +++++++++++++++----------
 arch/mips/include/asm/mmiowb.h         |   4 +-
 arch/mips/include/asm/smp-ops.h        |   2 -
 arch/mips/include/asm/smp.h            |   4 +-
 arch/mips/kernel/setup.c               |   1 +
 arch/mips/pci/pci-ip27.c               |   3 +
 arch/parisc/include/asm/io.h           |   2 -
 arch/powerpc/include/asm/io.h          |   1 -
 arch/sh/include/asm/io.h               |   2 -
 arch/sparc/include/asm/io_64.h         |   1 -
 drivers/video/fbdev/aty/atyfb_base.c   |   4 +
 15 files changed, 88 insertions(+), 73 deletions(-)

2.41.0