[PATCH v2 1/3] powerpc/32: Add ioremap_wt()

From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
	linux-block@vger.kernel.org, linux-m68k@lists.linux-m68k.org
Subject: [PATCH v2 1/3] powerpc/32: Add ioremap_wt()
Date: Mon, 27 Aug 2018 16:10:21 +0000 (UTC)	[thread overview]
Message-ID: <ab6b6c60d921335b44c100c5018fcc6585f05c24.1535385970.git.christophe.leroy@c-s.fr> (raw)

Other arches have ioremap_wt() to map IO areas write-through.
Implement it on PPC as well in order to avoid drivers using
__ioremap(_PAGE_WRITETHRU)

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 v2: no change

 arch/powerpc/include/asm/io.h | 6 ++++++
 arch/powerpc/mm/pgtable_32.c  | 8 ++++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index e0331e754568..3380b5b22450 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -3,6 +3,9 @@
 #ifdef __KERNEL__
 
 #define ARCH_HAS_IOREMAP_WC
+#ifdef CONFIG_PPC32
+#define ARCH_HAS_IOREMAP_WT
+#endif
 
 /*
  * This program is free software; you can redistribute it and/or
@@ -746,6 +749,8 @@ static inline void iosync(void)
  *
  * * ioremap_wc enables write combining
  *
+ * * ioremap_wt enables write through
+ *
  * * iounmap undoes such a mapping and can be hooked
  *
  * * __ioremap_at (and the pending __iounmap_at) are low level functions to
@@ -767,6 +772,7 @@ extern void __iomem *ioremap(phys_addr_t address, unsigned long size);
 extern void __iomem *ioremap_prot(phys_addr_t address, unsigned long size,
 				  unsigned long flags);
 extern void __iomem *ioremap_wc(phys_addr_t address, unsigned long size);
+void __iomem *ioremap_wt(phys_addr_t address, unsigned long size);
 #define ioremap_nocache(addr, size)	ioremap((addr), (size))
 #define ioremap_uc(addr, size)		ioremap((addr), (size))
 #define ioremap_cache(addr, size) \
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 120a49bfb9c6..528999738645 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -90,6 +90,14 @@ ioremap_wc(phys_addr_t addr, unsigned long size)
 EXPORT_SYMBOL(ioremap_wc);
 
 void __iomem *
+ioremap_wt(phys_addr_t addr, unsigned long size)
+{
+	return __ioremap_caller(addr, size, _PAGE_WRITETHRU,
+				__builtin_return_address(0));
+}
+EXPORT_SYMBOL(ioremap_wt);
+
+void __iomem *
 ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags)
 {
 	/* writeable implies dirty for kernel addresses */
-- 
2.13.3
