linux-kernel - [PATCH 37/37] asm-generic/io.h: drop inb() etc for HAS

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Date:   Fri, 29 Apr 2022 15:51:05 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-pci@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>
Subject: [PATCH 37/37] asm-generic/io.h: drop inb() etc for HAS_IOPORT=n

With all subsystems and drivers either declaring their dependence on
HAS_IOPORT or ifdeffing I/O port specific code sections we can finally
make inb()/outb() and friends compile-time dependent on HAS_IOPORT as
suggested by Linus in the linked mail. The main benefit of this is that
on platforms such as s390 which have no meaningful way of implementing
inb()/outb() their use without the proper HAS_IOPORT dependency will
result in easy to catch and fix compile-time errors instead of compiling
code that can never work.

Link: https://lore.kernel.org/lkml/CAHk-=wg80je=K7madF4e7WrRNp37e3qh6y10Svhdc7O8SZ_-8g@mail.gmail.com/
Co-developed-by: Arnd Bergmann <arnd@...nel.org>
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
 include/asm-generic/io.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 7ce93aaf69f8..b2572b2eab07 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -448,6 +448,7 @@ static inline void writesq(volatile void __iomem *addr, const void *buffer,
 #define IO_SPACE_LIMIT 0xffff
 #endif
 
+#ifdef CONFIG_HAS_IOPORT
 /*
  * {in,out}{b,w,l}() access little endian I/O. {in,out}{b,w,l}_p() can be
  * implemented on hardware that needs an additional delay for I/O accesses to
@@ -522,9 +523,12 @@ static inline void _outl(u32 value, unsigned long addr)
 	__io_paw();
 }
 #endif
+#endif /* CONFIG_HAS_IOPORT */
 
 #include <linux/logic_pio.h>
 
+#ifdef CONFIG_HAS_IOPORT
+
 #ifndef inb
 #define inb _inb
 #endif
@@ -703,6 +707,7 @@ static inline void outsl_p(unsigned long addr, const void *buffer,
 	outsl(addr, buffer, count);
 }
 #endif
+#endif /* CONFIG_HAS_IOPORT */
 
 #ifndef CONFIG_GENERIC_IOMAP
 #ifndef ioread8
-- 
2.32.0