From patchwork Sat Dec 18 22:27:10 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Holler X-Patchwork-Id: 76100 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from theia.denx.de (theia.denx.de [85.214.87.163]) by ozlabs.org (Postfix) with ESMTP id C9922B70A3 for ; Sun, 19 Dec 2010 09:27:34 +1100 (EST) Received: from localhost (localhost [127.0.0.1]) by theia.denx.de (Postfix) with ESMTP id 8A9D3280DF; Sat, 18 Dec 2010 23:27:33 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at theia.denx.de Received: from theia.denx.de ([127.0.0.1]) by localhost (theia.denx.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xX2sYJkTOWlN; Sat, 18 Dec 2010 23:27:33 +0100 (CET) Received: from theia.denx.de (localhost [127.0.0.1]) by theia.denx.de (Postfix) with ESMTP id 735E6280CE; Sat, 18 Dec 2010 23:27:32 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by theia.denx.de (Postfix) with ESMTP id 12E04280CE for ; Sat, 18 Dec 2010 23:27:30 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at theia.denx.de Received: from theia.denx.de ([127.0.0.1]) by localhost (theia.denx.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id iJlP-1aTjaWq for ; Sat, 18 Dec 2010 23:27:28 +0100 (CET) X-policyd-weight: NOT_IN_SBL_XBL_SPAMHAUS=-1.5 NOT_IN_SPAMCOP=-1.5 NOT_IN_BL_NJABL=-1.5 (only DNSBL check requested) Received: from mail.ahsoftware.de (h1047321.serverkompetenz.net [85.214.67.163]) by theia.denx.de (Postfix) with ESMTPS id 05627280C4 for ; Sat, 18 Dec 2010 23:27:26 +0100 (CET) Received: by mail.ahsoftware.de (Postfix, from userid 65534) id A98BE9C14F; Sat, 18 Dec 2010 23:27:26 +0100 (CET) Received: from eiche.ahsoftware (p57B20F2F.dip0.t-ipconnect.de [87.178.15.47]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.ahsoftware.de (Postfix) with ESMTP id 17E509C14E; Sat, 18 Dec 2010 23:27:24 +0100 (CET) Received: from beagle.ahsoftware (conradbt.ahsoftware [192.168.213.4]) by eiche.ahsoftware (Postfix) with ESMTP id E18923FCE9; Sat, 18 Dec 2010 23:27:22 +0100 (CET) From: Alexander Holler To: u-boot@lists.denx.de Date: Sat, 18 Dec 2010 23:27:10 +0100 Message-Id: <1292711230-3234-1-git-send-email-holler@ahsoftware.de> X-Mailer: git-send-email 1.7.2.2 Subject: [U-Boot] [RFC PATCH v2] ARM: Avoid compiler optimization for usages of readb, writeb and friends. X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.9 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: u-boot-bounces@lists.denx.de Errors-To: u-boot-bounces@lists.denx.de gcc 4.5.1 seems to ignore (at least some) volatile definitions, avoid that as done in the kernel. Reading C99 6.7.3 8 and the comment 114) there, I think it is a bug of that gcc version to ignore the volatile type qualifier used e.g. in __arch_getl(). Anyway, using a definition as in the kernel headers avoids such optimizations when gcc 4.5.1 is used. Maybe the headers as used in the current linux-kernel should be used, but to avoid large changes, I've just added a small change to the current headers. Signed-off-by: Alexander Holler Acked-by: Dirk Behme --- arch/arm/include/asm/io.h | 20 ++++++++++++++------ 1 files changed, 14 insertions(+), 6 deletions(-) diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index ff1518e..5364b78 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -125,13 +125,21 @@ extern inline void __raw_readsl(unsigned int addr, void *data, int longlen) #define __raw_readw(a) __arch_getw(a) #define __raw_readl(a) __arch_getl(a) -#define writeb(v,a) __arch_putb(v,a) -#define writew(v,a) __arch_putw(v,a) -#define writel(v,a) __arch_putl(v,a) +/* + * TODO: The kernel offers some more advanced versions of barriers, it might + * have some advantages to use them instead of the simple one here. + */ +#define dmb() __asm__ __volatile__ ("" : : : "memory") +#define __iormb() dmb() +#define __iowmb() dmb() + +#define writeb(v,c) ({ __iowmb(); __arch_putb(v,c); }) +#define writew(v,c) ({ __iowmb(); __arch_putw(v,c); }) +#define writel(v,c) ({ __iowmb(); __arch_putl(v,c); }) -#define readb(a) __arch_getb(a) -#define readw(a) __arch_getw(a) -#define readl(a) __arch_getl(a) +#define readb(c) ({ u8 __v = __arch_getb(c); __iormb(); __v; }) +#define readw(c) ({ u16 __v = __arch_getw(c); __iormb(); __v; }) +#define readl(c) ({ u32 __v = __arch_getl(c); __iormb(); __v; }) /* * The compiler seems to be incapable of optimising constants