Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752972AbbF3W50 (ORCPT ); Tue, 30 Jun 2015 18:57:26 -0400 Received: from mail-wi0-f176.google.com ([209.85.212.176]:38311 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751042AbbF3W5S (ORCPT ); Tue, 30 Jun 2015 18:57:18 -0400 MIME-Version: 1.0 In-Reply-To: <20150622161002.GB8240@lst.de> References: <20150622081028.35954.89885.stgit@dwillia2-desk3.jf.intel.com> <20150622082427.35954.73529.stgit@dwillia2-desk3.jf.intel.com> <20150622161002.GB8240@lst.de> Date: Tue, 30 Jun 2015 15:57:16 -0700 Message-ID: Subject: Re: [PATCH v5 2/6] arch: unify ioremap prototypes and macro aliases From: Dan Williams To: Christoph Hellwig Cc: Arnd Bergmann , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Thomas Gleixner , Ross Zwisler , Andrew Morton , Juergen Gross , X86 ML , "Kani, Toshimitsu" , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Luis Rodriguez , Konrad Rzeszutek Wilk , "linux-kernel@vger.kernel.org" , Stefan Bader , Andy Lutomirski , linux-mm@kvack.org, Geert Uytterhoeven , Ralf Baechle , Henrique de Moraes Holschuh , mpe@ellerman.id.au, Tejun Heo , Paul Mackerras , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3990 Lines: 96 On Mon, Jun 22, 2015 at 9:10 AM, Christoph Hellwig wrote: > On Mon, Jun 22, 2015 at 04:24:27AM -0400, Dan Williams wrote: >> Some archs define the first parameter to ioremap() as unsigned long, >> while the balance define it as resource_size_t. Unify on >> resource_size_t to enable passing ioremap function pointers. Also, some >> archs use function-like macros for defining ioremap aliases, but >> asm-generic/io.h expects object-like macros, unify on the latter. >> >> Move all handling of ioremap aliasing (i.e. ioremap_wt => ioremap) to >> include/linux/io.h. Add a check to include/linux/io.h to warn at >> compile time if an arch violates expectations. >> >> Kill ARCH_HAS_IOREMAP_WC and ARCH_HAS_IOREMAP_WT in favor of just >> testing for ioremap_wc, and ioremap_wt being defined. This arrangement >> allows drivers to know when ioremap_ are being re-directed to plain >> ioremap. >> >> Reported-by: kbuild test robot >> Signed-off-by: Dan Williams > > Hmm, this is quite a bit of churn, and doesn't make the interface lot > more obvious. > > I guess it's enough to get the pmem related bits going, but I'd really > prefer defining the ioremap* prototype in linux/io.h and requiring > and out of line implementation in the architectures, it's not like > it's a fast path. And to avoid the ifdef mess make it something like: > > void __iomem *ioremap_flags(resource_size_t offset, unsigned long size, > unsigned long prot_val, unsigned flags); Doesn't 'flags' imply a specific 'prot_val'? > static inline void __iomem *ioremap(resource_size_t offset, unsigned long size) > { > return ioremap_flags(offset, size, 0, 0); > } > > static inline void __iomem *ioremap_prot(resource_size_t offset, > unsigned long size, unsigned long prot_val) > { > return ioremap_flags(offset, size, prot_val, 0); > } > > static inline void __iomem *ioremap_nocache(resource_size_t offset, > unsigned long size) > { > return ioremap_flags(offset, size, 0, IOREMAP_NOCACHE); > } > > static inline void __iomem *ioremap_cache(resource_size_t offset, > unsigned long size) > { > return ioremap_flags(offset, size, 0, IOREMAP_CACHE); > } > > static inline void __iomem *ioremap_uc(resource_size_t offset, > unsigned long size) > { > return ioremap_flags(offset, size, 0, IOREMAP_UC); > } > > static inline void __iomem *ioremap_wc(resource_size_t offset, > unsigned long size) > { > return ioremap_flags(offset, size, 0, IOREMAP_WC); > } > > static inline void __iomem *ioremap_wt(resource_size_t offset, > unsigned long size) > { > return ioremap_flags(offset, size, 0, IOREMAP_WT); > } > > With all wrappers but ioremap() itself deprecated in the long run. > > Besides following the one API one prototype guideline this gives > us one proper entry point for all the variants. Additionally > it can reject non-supported caching modes at run time, e.g. because > different hardware may or may not support it. Additionally it > avoids the need for all these HAVE_IOREMAP_FOO defines, which need > constant updating. One useful feature of the ifdef mess as implemented in the patch is that you could test for whether ioremap_cache() is actually implemented or falls back to default ioremap(). I think for completeness archs should publish an ioremap type capabilities mask for drivers that care... (I can imagine pmem caring), or default to being permissive if something like IOREMAP_STRICT is not set. There's also the wrinkle of archs that can only support certain types of mappings at a given alignment. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/