[PATCH] nd_blk: Remove mmio_flush_range()

mmio_flush_range() suffers from a lack of clearly-defined semantics,
and is somewhat ambiguous to port to other architectures where the
scope of the writeback implied by "flush" and ordering might matter,
but MMIO would tend to imply non-cacheable anyway. Per the rationale
in 67a3e8fe9015 ("nd_blk: change aperture mapping from WC to WB"), the
only existing use is actually to invalidate clean cache lines for
ARCH_MEMREMAP_PMEM type mappings *without* writeback. Since the recent
cleanup of the pmem API, that also now happens to be the exact purpose
of arch_invalidate_pmem(), which would be a far more well-defined tool
for the job.

Rather than risk potentially inconsistent implementations of
mmio_flush_range() for the sake of one callsite, streamline things by
removing it entirely and instead move the ARCH_MEMREMAP_PMEM related
definitions up to the libnvdimm level, so they can be shared by NFIT
as well. This allows NFIT to be enabled for arm64.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 arch/x86/Kconfig                  |  1 -
 arch/x86/include/asm/cacheflush.h |  2 --
 drivers/acpi/nfit/Kconfig         |  1 -
 drivers/acpi/nfit/core.c          |  2 +-
 drivers/nvdimm/pmem.h             | 14 --------------
 include/linux/libnvdimm.h         | 15 +++++++++++++++
 lib/Kconfig                       |  3 ---
 tools/testing/nvdimm/test/nfit.c  |  4 ++--
 8 files changed, 18 insertions(+), 24 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 781521b7cf9e..5f3b756ec0d3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig

@@ -53,7 +53,6 @@ config X86
        select ARCH_HAS_FORTIFY_SOURCE
        select ARCH_HAS_GCOV_PROFILE_ALL
        select ARCH_HAS_KCOV                    if X86_64
-       select ARCH_HAS_MMIO_FLUSH
        select ARCH_HAS_PMEM_API                if X86_64
        select ARCH_HAS_UACCESS_FLUSHCACHE      if X86_64
        select ARCH_HAS_SET_MEMORY

diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index 8b4140f6724f..cb9a1af109b4 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h

@@ -7,6 +7,4 @@

 void clflush_cache_range(void *addr, unsigned int size);

-#define mmio_flush_range(addr, size) clflush_cache_range(addr, size)
-
 #endif /* _ASM_X86_CACHEFLUSH_H */

diff --git a/drivers/acpi/nfit/Kconfig b/drivers/acpi/nfit/Kconfig
index 6d3351452ea2..97117ba582f3 100644
--- a/drivers/acpi/nfit/Kconfig
+++ b/drivers/acpi/nfit/Kconfig

@@ -2,7 +2,6 @@ config ACPI_NFIT
        tristate "ACPI NVDIMM Firmware Interface Table (NFIT)"
        depends on PHYS_ADDR_T_64BIT
        depends on BLK_DEV
-       depends on ARCH_HAS_MMIO_FLUSH