linux-kernel - [PATCH 5/6] mips: drop GENERIC

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Message-Id: <20250315105907.1275012-6-arnd@kernel.org>
Date: Sat, 15 Mar 2025 11:59:06 +0100
From: Arnd Bergmann <arnd@...nel.org>
To: linux-arch@...r.kernel.org
Cc: Arnd Bergmann <arnd@...db.de>,
	Richard Henderson <richard.henderson@...aro.org>,
	Matt Turner <mattst88@...il.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Greg Ungerer <gerg@...ux-m68k.org>,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
	Helge Deller <deller@....de>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>,
	Rich Felker <dalias@...c.org>,
	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
	Julian Vetter <julian@...er-limits.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-alpha@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-m68k@...ts.linux-m68k.org,
	linux-mips@...r.kernel.org,
	linux-parisc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-sh@...r.kernel.org
Subject: [PATCH 5/6] mips: drop GENERIC_IOMAP wrapper

From: Arnd Bergmann <arnd@...db.de>

All PIO on MIPS platforms is memory mapped, so there is no benefit in
the lib/iomap.c wrappers that switch between inb/outb and readb/writeb
style accessses.

In fact, the '#define PIO_RESERVED 0' setting completely disables
the GENERIC_IOMAP functionality, and the '#define PIO_OFFSET
mips_io_port_base' setting is based on a misunderstanding of what the
offset is meant to do.

MIPS started using GENERIC_IOMAP in 2018 with commit b962aeb02205 ("MIPS:
Use GENERIC_IOMAP") replacing a simple custom implementation of the same
interfaces, but at the time the asm-generic/io.h version was not usable
yet. Since the header is now always included, it's now possible to go
back to the even simpler version.

Use the normal GENERIC_PCI_IOMAP functionality for all mips platforms
without the hacky GENERIC_IOMAP, and provide a custom pci_iounmap()
for the CONFIG_PCI_DRIVERS_LEGACY case to ensure the I/O port base never
gets unmapped.

The readsl() prototype needs an extra 'const' keyword to make it
compatible with the generic ioread32_rep() alias.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/mips/Kconfig          |  2 +-
 arch/mips/include/asm/io.h | 21 ++++++++-------------
 arch/mips/lib/iomap-pci.c  |  9 +++++++++
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 1924f2d83932..2a2120a6d852 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -38,7 +38,6 @@ config MIPS
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
 	select GENERIC_GETTIMEOFDAY
-	select GENERIC_IOMAP
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_ISA_DMA if EISA
@@ -47,6 +46,7 @@ config MIPS
 	select GENERIC_LIB_CMPDI2
 	select GENERIC_LIB_LSHRDI3
 	select GENERIC_LIB_UCMPDI2
+	select GENERIC_PCI_IOMAP
 	select GENERIC_SCHED_CLOCK if !CAVIUM_OCTEON_SOC
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_IDLE_POLL_SETUP
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 0bddb568af7c..1fe56d1870a6 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -66,17 +66,6 @@ static inline void set_io_port_base(unsigned long base)
 	mips_io_port_base = base;
 }
 
-/*
- * Provide the necessary definitions for generic iomap. We make use of
- * mips_io_port_base for iomap(), but we don't reserve any low addresses for
- * use with I/O ports.
- */
-
-#define HAVE_ARCH_PIO_SIZE
-#define PIO_OFFSET	mips_io_port_base
-#define PIO_MASK	IO_SPACE_LIMIT
-#define PIO_RESERVED	0x0UL
-
 /*
  * Enforce in-order execution of data I/O.  In the MIPS architecture
  * these are equivalent to corresponding platform-specific memory
@@ -397,8 +386,8 @@ static inline void writes##bwlq(volatile void __iomem *mem,		\
 	}								\
 }									\
 									\
-static inline void reads##bwlq(volatile void __iomem *mem, void *addr,	\
-			       unsigned int count)			\
+static inline void reads##bwlq(const volatile void __iomem *mem,	\
+			       void *addr, unsigned int count)		\
 {									\
 	volatile type *__addr = addr;					\
 									\
@@ -555,6 +544,12 @@ extern void (*_dma_cache_inv)(unsigned long start, unsigned long size);
 
 void __ioread64_copy(void *to, const void __iomem *from, size_t count);
 
+#ifdef CONFIG_PCI_DRIVERS_LEGACY
+struct pci_dev;
+void pci_iounmap(struct pci_dev *dev, void __iomem *addr);
+#define pci_iounmap pci_iounmap
+#endif
+
 #include <asm-generic/io.h>
 
 static inline void *isa_bus_to_virt(unsigned long address)
diff --git a/arch/mips/lib/iomap-pci.c b/arch/mips/lib/iomap-pci.c
index a9cb28813f0b..2f82c776c6d0 100644
--- a/arch/mips/lib/iomap-pci.c
+++ b/arch/mips/lib/iomap-pci.c
@@ -43,4 +43,13 @@ void __iomem *__pci_ioport_map(struct pci_dev *dev,
 	return (void __iomem *) (ctrl->io_map_base + port);
 }
 
+void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
+{
+	struct pci_controller *ctrl = dev->bus->sysdata;
+	void __iomem *base = (void __iomem *)ctrl->io_map_base;
+
+	if (addr < base || addr > (base + resource_size(ctrl->io_resource)))
+		iounmap(addr);
+}
+
 #endif /* CONFIG_PCI_DRIVERS_LEGACY */
-- 
2.39.5