iomap: constify ioreadX() iomem argument (as in generic implementation)

Patch series "iomap: Constify ioreadX() iomem argument", v3.

The ioread8/16/32() and others have inconsistent interface among the
architectures: some taking address as const, some not.

It seems there is nothing really stopping all of them to take pointer to
const.

This patch (of 4):

The ioreadX() and ioreadX_rep() helpers have inconsistent interface.  On
some architectures void *__iomem address argument is a pointer to const,
on some not.

Implementations of ioreadX() do not modify the memory under the address so
they can be converted to a "const" version for const-safety and
consistency among architectures.

[krzk@kernel.org: sh: clk: fix assignment from incompatible pointer type for ioreadX()]
  Link: http://lkml.kernel.org/r/20200723082017.24053-1-krzk@kernel.org
[akpm@linux-foundation.org: fix drivers/mailbox/bcm-pdc-mailbox.c]
  Link: http://lkml.kernel.org/r/202007132209.Rxmv4QyS%25lkp@intel.com

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Allen Hubbe <allenbh@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Link: http://lkml.kernel.org/r/20200709072837.5869-1-krzk@kernel.org
Link: http://lkml.kernel.org/r/20200709072837.5869-2-krzk@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/arch/alpha/include/asm/io_trivial.h b/arch/alpha/include/asm/io_trivial.h
index ba3d8f0cfe0c..a1a29cbe02fa 100644
--- a/arch/alpha/include/asm/io_trivial.h
+++ b/arch/alpha/include/asm/io_trivial.h
@@ -7,15 +7,15 @@
 
 #if IO_CONCAT(__IO_PREFIX,trivial_io_bw)
 __EXTERN_INLINE unsigned int
-IO_CONCAT(__IO_PREFIX,ioread8)(void __iomem *a)
+IO_CONCAT(__IO_PREFIX,ioread8)(const void __iomem *a)
 {
-	return __kernel_ldbu(*(volatile u8 __force *)a);
+	return __kernel_ldbu(*(const volatile u8 __force *)a);
 }
 
 __EXTERN_INLINE unsigned int
-IO_CONCAT(__IO_PREFIX,ioread16)(void __iomem *a)
+IO_CONCAT(__IO_PREFIX,ioread16)(const void __iomem *a)
 {
-	return __kernel_ldwu(*(volatile u16 __force *)a);
+	return __kernel_ldwu(*(const volatile u16 __force *)a);
 }
 
 __EXTERN_INLINE void
@@ -33,9 +33,9 @@ IO_CONCAT(__IO_PREFIX,iowrite16)(u16 b, void __iomem *a)
 
 #if IO_CONCAT(__IO_PREFIX,trivial_io_lq)
 __EXTERN_INLINE unsigned int
-IO_CONCAT(__IO_PREFIX,ioread32)(void __iomem *a)
+IO_CONCAT(__IO_PREFIX,ioread32)(const void __iomem *a)
 {
-	return *(volatile u32 __force *)a;
+	return *(const volatile u32 __force *)a;
 }
 
 __EXTERN_INLINE void
@@ -73,14 +73,14 @@ IO_CONCAT(__IO_PREFIX,writew)(u16 b, volatile void __iomem *a)
 __EXTERN_INLINE u8
 IO_CONCAT(__IO_PREFIX,readb)(const volatile void __iomem *a)
 {
-	void __iomem *addr = (void __iomem *)a;
+	const void __iomem *addr = (const void __iomem *)a;
 	return IO_CONCAT(__IO_PREFIX,ioread8)(addr);
 }
 
 __EXTERN_INLINE u16
 IO_CONCAT(__IO_PREFIX,readw)(const volatile void __iomem *a)
 {
-	void __iomem *addr = (void __iomem *)a;
+	const void __iomem *addr = (const void __iomem *)a;
 	return IO_CONCAT(__IO_PREFIX,ioread16)(addr);
 }