From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Alan Stern <stern@rowland.harvard.edu>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-pci@vger.kernel.org, Arnd Bergmann <arnd@kernel.org>
Subject: [PATCH v3 38/38] asm-generic/io.h: drop inb() etc for HAS_IOPORT=n
Date:   Tue, 14 Mar 2023 13:12:16 +0100
Message-Id: <20230314121216.413434-39-schnelle@linux.ibm.com>
In-Reply-To: <20230314121216.413434-1-schnelle@linux.ibm.com>
References: <20230314121216.413434-1-schnelle@linux.ibm.com>
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With all subsystems and drivers either declaring their dependence on
HAS_IOPORT or fencing 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@kernel.org>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 include/asm-generic/io.h | 60 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 4c44a29b5e8e..a13fe19b55a9 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -539,6 +539,7 @@ static inline void writesq(volatile void __iomem *addr, const void *buffer,
 
 #if !defined(inb) && !defined(_inb)
 #define _inb _inb
+#ifdef CONFIG_HAS_IOPORT
 static inline u8 _inb(unsigned long addr)
 {
 	u8 val;
@@ -548,10 +549,15 @@ static inline u8 _inb(unsigned long addr)
 	__io_par(val);
 	return val;
 }
+#else
+u8 _inb(unsigned long addr)
+	__compiletime_error("inb()) requires CONFIG_HAS_IOPORT");
+#endif
 #endif
 
 #if !defined(inw) && !defined(_inw)
 #define _inw _inw
+#ifdef CONFIG_HAS_IOPORT
 static inline u16 _inw(unsigned long addr)
 {
 	u16 val;
@@ -561,10 +567,15 @@ static inline u16 _inw(unsigned long addr)
 	__io_par(val);
 	return val;
 }
+#else
+u16 _inw(unsigned long addr)
+	__compiletime_error("inw() requires CONFIG_HAS_IOPORT");
+#endif
 #endif
 
 #if !defined(inl) && !defined(_inl)
 #define _inl _inl
+#ifdef CONFIG_HAS_IOPORT
 static inline u32 _inl(unsigned long addr)
 {
 	u32 val;
@@ -574,36 +585,55 @@ static inline u32 _inl(unsigned long addr)
 	__io_par(val);
 	return val;
 }
+#else
+u32 _inl(unsigned long addr)
+	__compiletime_error("inl() requires CONFIG_HAS_IOPORT");
+#endif
 #endif
 
 #if !defined(outb) && !defined(_outb)
 #define _outb _outb
+#ifdef CONFIG_HAS_IOPORT
 static inline void _outb(u8 value, unsigned long addr)
 {
 	__io_pbw();
 	__raw_writeb(value, PCI_IOBASE + addr);
 	__io_paw();
 }
+#else
+void _outb(u8 value, unsigned long addr)
+	__compiletime_error("outb() requires CONFIG_HAS_IOPORT");
+#endif
 #endif
 
 #if !defined(outw) && !defined(_outw)
 #define _outw _outw
+#ifdef CONFIG_HAS_IOPORT
 static inline void _outw(u16 value, unsigned long addr)
 {
 	__io_pbw();
 	__raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
 	__io_paw();
 }
+#else
+void _outw(u16 value, unsigned long addr)
+	__compiletime_error("outw() requires CONFIG_HAS_IOPORT");
+#endif
 #endif
 
 #if !defined(outl) && !defined(_outl)
 #define _outl _outl
+#ifdef CONFIG_HAS_IOPORT
 static inline void _outl(u32 value, unsigned long addr)
 {
 	__io_pbw();
 	__raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
 	__io_paw();
 }
+#else
+void _outl(u32 value, unsigned long addr)
+	__compiletime_error("outl() requires CONFIG_HAS_IOPORT");
+#endif
 #endif
 
 #include <linux/logic_pio.h>
@@ -687,53 +717,83 @@ static inline void outl_p(u32 value, unsigned long addr)
 
 #ifndef insb
 #define insb insb
+#ifdef CONFIG_HAS_IOPORT
 static inline void insb(unsigned long addr, void *buffer, unsigned int count)
 {
 	readsb(PCI_IOBASE + addr, buffer, count);
 }
+#else
+void insb(unsigned long addr, void *buffer, unsigned int count)
+	__compiletime_error("insb() requires HAS_IOPORT");
+#endif
 #endif
 
 #ifndef insw
 #define insw insw
+#ifdef CONFIG_HAS_IOPORT
 static inline void insw(unsigned long addr, void *buffer, unsigned int count)
 {
 	readsw(PCI_IOBASE + addr, buffer, count);
 }
+#else
+void insw(unsigned long addr, void *buffer, unsigned int count)
+	__compiletime_error("insw() requires HAS_IOPORT");
+#endif
 #endif
 
 #ifndef insl
 #define insl insl
+#ifdef CONFIG_HAS_IOPORT
 static inline void insl(unsigned long addr, void *buffer, unsigned int count)
 {
 	readsl(PCI_IOBASE + addr, buffer, count);
 }
+#else
+void insl(unsigned long addr, void *buffer, unsigned int count)
+	__compiletime_error("insl() requires HAS_IOPORT");
+#endif
 #endif
 
 #ifndef outsb
 #define outsb outsb
+#ifdef CONFIG_HAS_IOPORT
 static inline void outsb(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
 	writesb(PCI_IOBASE + addr, buffer, count);
 }
+#else
+void outsb(unsigned long addr, const void *buffer, unsigned int count)
+	__compiletime_error("outsb() requires HAS_IOPORT");
+#endif
 #endif
 
 #ifndef outsw
 #define outsw outsw
+#ifdef CONFIG_HAS_IOPORT
 static inline void outsw(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
 	writesw(PCI_IOBASE + addr, buffer, count);
 }
+#else
+void outsw(unsigned long addr, const void *buffer, unsigned int count)
+	__compiletime_error("outsw() requires HAS_IOPORT");
+#endif
 #endif
 
 #ifndef outsl
 #define outsl outsl
+#ifdef CONFIG_HAS_IOPORT
 static inline void outsl(unsigned long addr, const void *buffer,
 			 unsigned int count)
 {
 	writesl(PCI_IOBASE + addr, buffer, count);
 }
+#else
+void outsl(unsigned long addr, const void *buffer, unsigned int count)
+	__compiletime_error("outsl() requires HAS_IOPORT");
+#endif
 #endif
 
 #ifndef insb_p
-- 
2.37.2