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From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Arnd Bergmann <arnd@arndb.de>, Vineet Gupta <vgupta@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        linux-snps-arc@lists.infradead.org, sparclinux@vger.kernel.org
Subject: [PATCH v4 2/3] risc-v: Use generic io.h helpers for nommu
Date:   Fri, 30 Apr 2021 13:16:40 +0200
Message-Id: <20210430111641.1911207-3-schnelle@linux.ibm.com>
In-Reply-To: <20210430111641.1911207-1-schnelle@linux.ibm.com>
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From: Niklas Schnelle <niklas@komani.de>

Without MMU support PCI_IOBASE is left undefined because PCI_IO_END is
VMEMMAP_START. Nevertheless the in*()/out*() helper macros are left
defined with uses of PCI_IOBASE. At the moment this only compiles
because asm-generic/io.h defines PCI_IOBASE as 0 if it is undefined and
so at macro expansion the macro is defined. This is suprising at the
least and leads to compilation errors when asm-generic/io.h is changed
to leave PCI_IOBASE undefined. Instead only define the in*()/out*()
helper macros with MMU support and fall back to the asm-generic/io.h
helper stubs otherwise.

Signed-off-by: Niklas Schnelle <niklas@komani.de>
---
 arch/riscv/include/asm/io.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index c025a746a148..31a8b98c0f13 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -23,12 +23,12 @@
 #include <asm/mmio.h>
 
 /*
- *  I/O port access constants.
+ *  I/O port access constants. Without MMU support leave PCI_IOBASE undefined
+ *  and fall back to generic stubs for I/O access routines.
  */
 #ifdef CONFIG_MMU
 #define IO_SPACE_LIMIT		(PCI_IO_SIZE - 1)
 #define PCI_IOBASE		((void __iomem *)PCI_IO_START)
-#endif /* CONFIG_MMU */
 
 /*
  * Emulation routines for the port-mapped IO space used by some PCI drivers.
@@ -145,6 +145,7 @@ __io_writes_outs(writes, u64, q, __io_bw(), __io_aw())
 __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
 #define outsq(addr, buffer, count) __outsq((void __iomem *)addr, buffer, count)
 #endif
+#endif /* CONFIG_MMU */
 
 #include <asm-generic/io.h>
 
-- 
2.31.1