asm-generic/iomap.h: remove ARCH_HAS_IOREMAP_xx macros

Patch series "mm: ioremap: Convert architectures to take GENERIC_IOREMAP
way", v8.

Motivation and implementation:
==============================
Currently, many architecutres have't taken the standard GENERIC_IOREMAP
way to implement ioremap_prot(), iounmap(), and ioremap_xx(), but make
these functions specifically under each arch's folder.  Those cause many
duplicated code of ioremap() and iounmap().

In this patchset, firstly introduce generic_ioremap_prot() and
generic_iounmap() to extract the generic code for GENERIC_IOREMAP.  By
taking GENERIC_IOREMAP method, the generic generic_ioremap_prot(),
generic_iounmap(), and their generic wrapper ioremap_prot(), ioremap() and
iounmap() are all visible and available to arch.  Arch needs to provide
wrapper functions to override the generic version if there's arch specific
handling in its corresponding ioremap_prot(), ioremap() or iounmap(). 
With these changes, duplicated ioremap/iounmap() code uder ARCH-es are
removed, and the equivalent functioality is kept as before.

Background info:
================

1) The converting more architectures to take GENERIC_IOREMAP way is
   suggested by Christoph in below discussion:
   https://lore.kernel.org/all/Yp7h0Jv6vpgt6xdZ@infradead.org/T/#u

2) In the previous v1 to v3, it's basically further action after arm64
   has converted to GENERIC_IOREMAP way in below patchset.  It's done by
   adding hook ioremap_allowed() and iounmap_allowed() in ARCH to add ARCH
   specific handling the middle of ioremap_prot() and iounmap().

[PATCH v5 0/6] arm64: Cleanup ioremap() and support ioremap_prot()
https://lore.kernel.org/all/20220607125027.44946-1-wangkefeng.wang@huawei.com/T/#u

Later, during v3 reviewing, Christophe Leroy suggested to introduce
generic_ioremap_prot() and generic_iounmap() to generic codes, and ARCH
can provide wrapper function ioremap_prot(), ioremap() or iounmap() if
needed.  Christophe made a RFC patchset as below to specially demonstrate
his idea.  This is what v4 and now v5 is doing.

[RFC PATCH 0/8] mm: ioremap: Convert architectures to take GENERIC_IOREMAP way
https://lore.kernel.org/all/cover.1665568707.git.christophe.leroy@csgroup.eu/T/#u

Testing:
========
In v8, I only applied this patchset onto the latest linus's tree to build
and run on arm64 and s390.


This patch (of 19):

Let's use '#define ioremap_xx' and "#ifdef ioremap_xx" instead.

To remove defined ARCH_HAS_IOREMAP_xx macros in <asm/io.h> of each ARCH,
the ARCH's own ioremap_wc|wt|np definition need be above "#include
<asm-generic/iomap.h>.  Otherwise the redefinition error would be seen
during compiling.  So the relevant adjustments are made to avoid compiling
error:

  loongarch:
  - doesn't include <asm-generic/iomap.h>, defining ARCH_HAS_IOREMAP_WC
    is redundant, so simply remove it.

  m68k:
  - selected GENERIC_IOMAP, <asm-generic/iomap.h> has been added in
    <asm-generic/io.h>, and <asm/kmap.h> is included above
    <asm-generic/iomap.h>, so simply remove ARCH_HAS_IOREMAP_WT defining.

  mips:
  - move "#include <asm-generic/iomap.h>" below ioremap_wc definition
    in <asm/io.h>

  powerpc:
  - remove "#include <asm-generic/iomap.h>" in <asm/io.h> because it's
    duplicated with the one in <asm-generic/io.h>, let's rely on the
    latter.

  x86:
  - selected GENERIC_IOMAP, remove #include <asm-generic/iomap.h> in
    the middle of <asm/io.h>. Let's rely on <asm-generic/io.h>.

Link: https://lkml.kernel.org/r/20230706154520.11257-2-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Helge Deller <deller@gmx.de>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/loongarch/include/asm/io.h

@@ -5,8 +5,6 @@
 #ifndef _ASM_IO_H
 #define _ASM_IO_H
 
-#define ARCH_HAS_IOREMAP_WC
-
 #include <linux/kernel.h>
 #include <linux/types.h>
 

arch/m68k/include/asm/io_mm.h

@@ -26,8 +26,6 @@
 #include <asm/virtconvert.h>
 #include <asm/kmap.h>
 
-#include <asm-generic/iomap.h>
-
 #ifdef CONFIG_ATARI
 #define atari_readb   raw_inb
 #define atari_writeb  raw_outb

arch/m68k/include/asm/kmap.h

@@ -4,8 +4,6 @@
 
 #ifdef CONFIG_MMU
 
-#define ARCH_HAS_IOREMAP_WT
-
 /* Values for nocacheflag and cmode */
 #define IOMAP_FULL_CACHING		0
 #define IOMAP_NOCACHE_SER		1

arch/mips/include/asm/io.h

@@ -12,8 +12,6 @@
 #ifndef _ASM_IO_H
 #define _ASM_IO_H
 
-#define ARCH_HAS_IOREMAP_WC
-
 #include <linux/compiler.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
@@ -25,7 +23,6 @@
 #include <asm/byteorder.h>
 #include <asm/cpu.h>
 #include <asm/cpu-features.h>
-#include <asm-generic/iomap.h>
 #include <asm/page.h>
 #include <asm/pgtable-bits.h>
 #include <asm/processor.h>
@@ -210,6 +207,8 @@ void iounmap(const volatile void __iomem *addr);
 #define ioremap_wc(offset, size)					\
 	ioremap_prot((offset), (size), boot_cpu_data.writecombine)
 
+#include <asm-generic/iomap.h>
+
 #if defined(CONFIG_CPU_CAVIUM_OCTEON)
 #define war_io_reorder_wmb()		wmb()
 #else

arch/powerpc/include/asm/io.h

@@ -3,11 +3,6 @@
 #define _ASM_POWERPC_IO_H
 #ifdef __KERNEL__
 
-#define ARCH_HAS_IOREMAP_WC
-#ifdef CONFIG_PPC32
-#define ARCH_HAS_IOREMAP_WT
-#endif
-
 /*
  */
 
@@ -732,9 +727,7 @@ static inline void name at					\
 #define writel_relaxed(v, addr)	writel(v, addr)
 #define writeq_relaxed(v, addr)	writeq(v, addr)
 
-#ifdef CONFIG_GENERIC_IOMAP
+#ifndef CONFIG_GENERIC_IOMAP
-#include <asm-generic/iomap.h>
-#else
 /*
  * Here comes the implementation of the IOMAP interfaces.
  */

arch/x86/include/asm/io.h

@@ -35,9 +35,6 @@
   *  - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   */
 
-#define ARCH_HAS_IOREMAP_WC
-#define ARCH_HAS_IOREMAP_WT
-
 #include <linux/string.h>
 #include <linux/compiler.h>
 #include <linux/cc_platform.h>
@@ -212,8 +209,6 @@ void memset_io(volatile void __iomem *, int, size_t);
 #define memcpy_toio memcpy_toio
 #define memset_io memset_io
 
-#include <asm-generic/iomap.h>
-
 /*
  * ISA space is 'always mapped' on a typical x86 system, no need to
  * explicitly ioremap() it. The fact that the ISA IO space is mapped

drivers/net/ethernet/sfc/io.h

@@ -70,7 +70,7 @@
  */
 #ifdef CONFIG_X86_64
 /* PIO is a win only if write-combining is possible */
-#ifdef ARCH_HAS_IOREMAP_WC
+#ifdef ioremap_wc
 #define EFX_USE_PIO 1
 #endif
 #endif

drivers/net/ethernet/sfc/siena/io.h

@@ -70,7 +70,7 @@
  */
 #ifdef CONFIG_X86_64
 /* PIO is a win only if write-combining is possible */
-#ifdef ARCH_HAS_IOREMAP_WC
+#ifdef ioremap_wc
 #define EFX_USE_PIO 1
 #endif
 #endif

include/asm-generic/iomap.h

@@ -93,15 +93,15 @@ extern void __iomem *ioport_map(unsigned long port, unsigned int nr);
 extern void ioport_unmap(void __iomem *);
 #endif
 
-#ifndef ARCH_HAS_IOREMAP_WC
+#ifndef ioremap_wc
 #define ioremap_wc ioremap
 #endif
 
-#ifndef ARCH_HAS_IOREMAP_WT
+#ifndef ioremap_wt
 #define ioremap_wt ioremap
 #endif
 
-#ifndef ARCH_HAS_IOREMAP_NP
+#ifndef ioremap_np
 /* See the comment in asm-generic/io.h about ioremap_np(). */
 #define ioremap_np ioremap_np
 static inline void __iomem *ioremap_np(phys_addr_t offset, size_t size)