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From: Christoph Hellwig <hch@lst.de>
To: Arnd Bergmann <arnd@arndb.de>, Guo Ren <guoren@kernel.org>,
	Michal Simek <monstr@monstr.eu>,
	Greentime Hu <green.hu@gmail.com>,
	Vincent Chen <deanbo422@gmail.com>, Guan Xuetao <gxt@pku.edu.cn>,
	x86@kernel.org
Cc: linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	nios2-dev@lists.rocketboards.org, openrisc@lists.librecores.org,
	linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org,
	linux-mtd@lists.infradead.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 11/21] asm-generic: don't provide ioremap for CONFIG_MMU
Date: Thu, 17 Oct 2019 19:45:44 +0200
Message-ID: <20191017174554.29840-12-hch@lst.de> (raw)
In-Reply-To: <20191017174554.29840-1-hch@lst.de>

All MMU-enabled ports have a non-trivial ioremap and should thus provide
the prototype for their implementation instead of providing a generic
one unless a different symbol is not defined.  Note that this only
affects sparc32 nds32 as all others do provide their own version.

Also update the kerneldoc comments in asm-generic/io.h to explain the
situation around the default ioremap* implementations correctly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/nds32/include/asm/io.h    |  2 ++
 arch/sparc/include/asm/io_32.h |  1 +
 include/asm-generic/io.h       | 29 ++++++++---------------------
 3 files changed, 11 insertions(+), 21 deletions(-)

diff --git a/arch/nds32/include/asm/io.h b/arch/nds32/include/asm/io.h
index 16f262322b8f..fb0e8a24c7af 100644
--- a/arch/nds32/include/asm/io.h
+++ b/arch/nds32/include/asm/io.h
@@ -6,6 +6,7 @@
 
 #include <linux/types.h>
 
+void __iomem *ioremap(phys_addr_t phys_addr, size_t size);
 extern void iounmap(volatile void __iomem *addr);
 #define __raw_writeb __raw_writeb
 static inline void __raw_writeb(u8 val, volatile void __iomem *addr)
@@ -80,4 +81,5 @@ static inline u32 __raw_readl(const volatile void __iomem *addr)
 #define writew(v,c)	({ __iowmb(); writew_relaxed((v),(c)); })
 #define writel(v,c)	({ __iowmb(); writel_relaxed((v),(c)); })
 #include <asm-generic/io.h>
+
 #endif /* __ASM_NDS32_IO_H */
diff --git a/arch/sparc/include/asm/io_32.h b/arch/sparc/include/asm/io_32.h
index df2dc1784673..9a52d9506f80 100644
--- a/arch/sparc/include/asm/io_32.h
+++ b/arch/sparc/include/asm/io_32.h
@@ -127,6 +127,7 @@ static inline void sbus_memcpy_toio(volatile void __iomem *dst,
  * Bus number may be embedded in the higher bits of the physical address.
  * This is why we have no bus number argument to ioremap().
  */
+void __iomem *ioremap(phys_addr_t offset, size_t size);
 void iounmap(volatile void __iomem *addr);
 /* Create a virtual mapping cookie for an IO port range */
 void __iomem *ioport_map(unsigned long port, unsigned int nr);
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index a98ed6325727..6a5edc23afe2 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -922,28 +922,16 @@ static inline void *phys_to_virt(unsigned long address)
 /**
  * DOC: ioremap() and ioremap_*() variants
  *
- * If you have an IOMMU your architecture is expected to have both ioremap()
- * and iounmap() implemented otherwise the asm-generic helpers will provide a
- * direct mapping.
+ * Architectures with an MMU are expected to provide ioremap() and iounmap()
+ * themselves.  For NOMMU architectures we provide a default nop-op
+ * implementation that expect that the physical address used for MMIO are
+ * already marked as uncached, and can be used as kernel virtual addresses.
  *
- * There are ioremap_*() call variants, if you have no IOMMU we naturally will
- * default to direct mapping for all of them, you can override these defaults.
- * If you have an IOMMU you are highly encouraged to provide your own
- * ioremap variant implementation as there currently is no safe architecture
- * agnostic default. To avoid possible improper behaviour default asm-generic
- * ioremap_*() variants all return NULL when an IOMMU is available. If you've
- * defined your own ioremap_*() variant you must then declare your own
- * ioremap_*() variant as defined to itself to avoid the default NULL return.
+ * ioremap_wc() and ioremap_wt() can provide more relaxed caching attributes
+ * for specific drivers if the architecture choses to implement them.  If they
+ * are not implemented we fall back to plain ioremap.
  */
 #ifndef CONFIG_MMU
-
-/*
- * Change "struct page" to physical address.
- *
- * This implementation is for the no-MMU case only... if you have an MMU
- * you'll need to provide your own definitions.
- */
-
 #ifndef ioremap
 #define ioremap ioremap
 static inline void __iomem *ioremap(phys_addr_t offset, size_t size)
@@ -954,14 +942,13 @@ static inline void __iomem *ioremap(phys_addr_t offset, size_t size)
 
 #ifndef iounmap
 #define iounmap iounmap
-
 static inline void iounmap(void __iomem *addr)
 {
 }
 #endif
 #endif /* CONFIG_MMU */
+
 #ifndef ioremap_nocache
-void __iomem *ioremap(phys_addr_t phys_addr, size_t size);
 #define ioremap_nocache ioremap_nocache
 static inline void __iomem *ioremap_nocache(phys_addr_t offset, size_t size)
 {
-- 
2.20.1


  parent reply index

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-17 17:45 generic ioremap (and lots of cleanups) v2 Christoph Hellwig
2019-10-17 17:45 ` [PATCH 01/21] arm: remove ioremap_cached Christoph Hellwig
2019-10-17 17:45 ` [PATCH 02/21] unicore32: " Christoph Hellwig
2019-10-17 17:45 ` [PATCH 03/21] ia64: rename ioremap_nocache to ioremap_uc Christoph Hellwig
2019-10-21  8:47   ` Sergei Shtylyov
2019-10-17 17:45 ` [PATCH 04/21] hexagon: clean up ioremap Christoph Hellwig
2019-10-17 17:45 ` [PATCH 05/21] alpha: remove the unused __ioremap wrapper Christoph Hellwig
2019-10-17 17:45 ` [PATCH 06/21] nios2: remove __ioremap Christoph Hellwig
2019-10-17 17:45 ` [PATCH 07/21] parisc: " Christoph Hellwig
2019-10-17 21:35   ` Rolf Eike Beer
2019-10-17 17:45 ` [PATCH 08/21] x86: clean up ioremap Christoph Hellwig
2019-10-21  8:23   ` Thomas Gleixner
2019-10-28 15:29     ` Christoph Hellwig
2019-10-17 17:45 ` [PATCH 09/21] xtensa: " Christoph Hellwig
2019-10-17 17:45 ` [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU Christoph Hellwig
2019-10-17 17:45 ` Christoph Hellwig [this message]
2019-10-17 17:45 ` [PATCH 12/21] arch: rely on asm-generic/io.h for default ioremap_* definitions Christoph Hellwig
2019-10-17 17:45 ` [PATCH 13/21] m68k: rename __iounmap and mark it static Christoph Hellwig
2019-10-18  7:30   ` Geert Uytterhoeven
2019-10-17 17:45 ` [PATCH 14/21] hexagon: remove __iounmap Christoph Hellwig
2019-10-17 17:45 ` [PATCH 15/21] nios2: " Christoph Hellwig
2019-10-17 17:45 ` [PATCH 16/21] sh: " Christoph Hellwig
2019-10-17 17:45 ` [PATCH 17/21] lib: provide a simple generic ioremap implementation Christoph Hellwig
2019-10-17 17:45 ` [PATCH 18/21] riscv: use the generic ioremap code Christoph Hellwig
2019-10-18  3:42   ` Paul Walmsley
2019-10-17 17:45 ` [PATCH 19/21] nds32: use generic ioremap Christoph Hellwig
2019-10-17 17:45 ` [PATCH 20/21] csky: remove ioremap_cache Christoph Hellwig
2019-10-21  7:58   ` Guo Ren
2019-11-05  1:26     ` Christoph Hellwig
2019-10-17 17:45 ` [PATCH 21/21] csky: use generic ioremap Christoph Hellwig
2019-10-29  6:48 generic ioremap (and lots of cleanups) v3 Christoph Hellwig
2019-10-29  6:48 ` [PATCH 11/21] asm-generic: don't provide ioremap for CONFIG_MMU Christoph Hellwig
2019-11-06 18:11   ` Palmer Dabbelt
2019-11-06 18:16     ` Geert Uytterhoeven
2019-11-06 18:28       ` Christoph Hellwig
2019-11-11 10:31       ` Arnd Bergmann
2019-11-11 10:29   ` Arnd Bergmann

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