Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753067AbaDQTQW (ORCPT ); Thu, 17 Apr 2014 15:16:22 -0400 Received: from asavdk4.altibox.net ([109.247.116.15]:36400 "EHLO asavdk4.altibox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752760AbaDQTQO (ORCPT ); Thu, 17 Apr 2014 15:16:14 -0400 Date: Thu, 17 Apr 2014 21:15:55 +0200 From: Sam Ravnborg To: Will Deacon Cc: "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "arnd@arndb.de" , "monstr@monstr.eu" , "dhowells@redhat.com" , "broonie@linaro.org" , "benh@kernel.crashing.org" , "peterz@infradead.org" , "paulmck@linux.vnet.ibm.com" Subject: Re: [PATCH 00/18] Cross-architecture definitions of relaxed MMIO accessors Message-ID: <20140417191555.GA11970@ravnborg.org> References: <1397742261-15621-1-git-send-email-will.deacon@arm.com> <20140417153638.GA7317@ravnborg.org> <20140417154714.GD30553@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140417154714.GD30553@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 17, 2014 at 04:47:15PM +0100, Will Deacon wrote: > Hi Sam, > > On Thu, Apr 17, 2014 at 04:36:38PM +0100, Sam Ravnborg wrote: > > On Thu, Apr 17, 2014 at 02:44:03PM +0100, Will Deacon wrote: > > > Hello, > > > > > > This RFC series attempts to define a portable (i.e. cross-architecture) > > > definition of the {readX,writeX}_relaxed MMIO accessor functions. These > > > functions are already in widespread use amongst drivers (mainly those supporting > > > devices embedded in ARM SoCs), but lack any well-defined semantics and, > > > subsequently, any portable definitions to allow these drivers to be compiled for > > > other architectures. > > > > Could this be made in such a way that only architectures that need > > to provide their own versions actually have to add them? > > > > The current patch-set adds the same dummy defines all over, > > and will put this burden also on new architectures. > > It shouldn't be a burden for new architectures, as they will use > asm-generic/io.h and get the definitions from there. Why is it then necesary to do this for sparc: diff --git a/arch/sparc/include/asm/io.h b/arch/sparc/include/asm/io.h index f6902cf3cbe9..493f22c4684f 100644 --- a/arch/sparc/include/asm/io.h +++ b/arch/sparc/include/asm/io.h @@ -10,6 +10,15 @@ * Defines used for both SPARC32 and SPARC64 */ +/* Relaxed accessors for MMIO */ +#define readb_relaxed(__addr) readb(__addr) +#define readw_relaxed(__addr) readw(__addr) +#define readl_relaxed(__addr) readl(__addr) + +#define writeb_relaxed(__b, __addr) writeb(__b, __addr) +#define writew_relaxed(__w, __addr) writew(__w, __addr) +#define writel_relaxed(__l, __addr) writel(__l, __addr) And similar for several other architectures. For asm-generic/io.h: +#ifndef readb_relaxed +#define readb_relaxed readb +#endif This has same effect as the above. Only difference is that the implementation in asm-generic lacks the arguments. The patch also breaks the pattern that the #define foobar foobar is on the line just above the static inline that implements the function. -#define readw readw +#define readw readw +#ifndef readw_relaxed +#define readw_relaxed readw +#endif Move this blow below the static inline would make this easier to understand. static inline u16 readw(const volatile void __iomem *addr) { return __le16_to_cpu(__raw_readw(addr)); } Sam -- 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/