From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 89C451DC9B4; Tue, 18 Mar 2025 20:39:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742330354; cv=none; b=ArfR+PXEzuWGFFZxU5FuyEUM78GwMMu/u7MUkhh3tjgi6fkJxXs3DEX4Od5UZyOPoize+QhZIl/6o+h+anCYmyZo+wZZPOgC5o14pDsiuyeY/QY5G51/0A5WMGY1z/Jb4ItfdYCND1oSvfWAlGs3GadsQs+TLLaOFs87shPEeKs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742330354; c=relaxed/simple; bh=qOyqx98uYZaxnz8iL9sLUntJPSrsmCPx493u7R+Lnjk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cOGtwWVAyFSuJjMA599/Rs32b7i3xyAsVVJR5MsODFj+tIted+V5+BnCoSbDC2mlYg134CQQwe/KE9TURCQvtLCqYcH1L1DcJo8YzBSE68k6BDq+/xjTrJlK11wj1De91x+nW+NjUUw7njUl9KPuOu9b3icxqG6tGv3DE2buToQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jmmQG2jQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jmmQG2jQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3B08C4CEDD; Tue, 18 Mar 2025 20:39:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742330354; bh=qOyqx98uYZaxnz8iL9sLUntJPSrsmCPx493u7R+Lnjk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jmmQG2jQTeVh/Wo0UkAwvIfRQMT2BJv/NcHjMw9/oC0Ydce8fyHd1L+aw+8KMafl3 daX59WrcnM3SoKrzxsQacaGdCwHn7j0cgltFaXcG0FWxhVFtnkslrkuZDIzDoRzRx4 IjWJucl8viLRZjB6jNb8ziUAEg2ZashS5lFUm9KOgrzWbB46qr5FlcAk0+otns60zv zhA+c7L2jF0UYcCtQPFuEa7cxrT2KfcgPaV1RSsgFeoXx2cdHyoL6Za5yJerW6sxM+ ny/JMURbcz1jhTP1rnK9+tp3IAUvGeP8ZRwA/QKlgFzadPDgO1TfdclmN0zu740gQG fWnpzczIdmTNw== Date: Tue, 18 Mar 2025 13:39:06 -0700 From: Nathan Chancellor To: Arnd Bergmann Cc: linux-arch@vger.kernel.org, Arnd Bergmann , Richard Henderson , Matt Turner , Geert Uytterhoeven , Greg Ungerer , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , Julian Vetter , Bjorn Helgaas , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org Subject: Re: [PATCH 5/6] mips: drop GENERIC_IOMAP wrapper Message-ID: <20250318203906.GA4089579@ax162> References: <20250315105907.1275012-1-arnd@kernel.org> <20250315105907.1275012-6-arnd@kernel.org> Precedence: bulk X-Mailing-List: linux-sh@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250315105907.1275012-6-arnd@kernel.org> Hi Arnd, On Sat, Mar 15, 2025 at 11:59:06AM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > 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 > --- > 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 > > 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 > This change as commit 976bf3aec388 ("mips: drop GENERIC_IOMAP wrapper") in -next introduces new instances of -Wnull-pointer-arithmetic when building certain mips configurations with clang. $ make -skj"$(nproc)" ARCH=mips LLVM=1 mrproper malta_defconfig init/main.o ... In file included from init/main.c:17: In file included from include/linux/module.h:17: In file included from include/linux/kmod.h:9: In file included from include/linux/umh.h:4: In file included from include/linux/gfp.h:7: In file included from include/linux/mmzone.h:22: In file included from include/linux/mm_types.h:5: In file included from include/linux/mm_types_task.h:14: In file included from arch/mips/include/asm/page.h:181: In file included from arch/mips/include/asm/io.h:553: include/asm-generic/io.h:1175:55: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] 1175 | return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port; | ~~~~~~~~~~ ^ 1 warning generated. Cheers, Nathan