Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756992AbcDJSs5 (ORCPT ); Sun, 10 Apr 2016 14:48:57 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52579 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932133AbcDJSsv (ORCPT ); Sun, 10 Apr 2016 14:48:51 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexey Brodkin , Arnd Bergmann , Lada Trimasova , Vineet Gupta Subject: [PATCH 4.5 156/238] ARC: [BE] readl()/writel() to work in Big Endian CPU configuration Date: Sun, 10 Apr 2016 11:35:33 -0700 Message-Id: <20160410183505.082315982@linuxfoundation.org> X-Mailer: git-send-email 2.8.0 In-Reply-To: <20160410183456.398741366@linuxfoundation.org> References: <20160410183456.398741366@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 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: 2497 Lines: 66 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lada Trimasova commit f778cc65717687a3d3f26dd21bef62cd059f1b8b upstream. read{l,w}() write{l,w}() primitives should use le{16,32}_to_cpu() and cpu_to_le{16,32}() respectively to ensure device registers are read correctly in Big Endian CPU configuration. Per Arnd Bergmann | Most drivers using readl() or readl_relaxed() expect those to perform byte | swaps on big-endian architectures, as the registers tend to be fixed endian This was needed for getting UART to work correctly on a Big Endian ARC. The ARC accessors originally were fine, and the bug got introduced inadventently by commit b8a033023994 ("ARCv2: barriers") Fixes: b8a033023994 ("ARCv2: barriers") Link: http://lkml.kernel.org/r/201603100845.30602.arnd@arndb.de Cc: Alexey Brodkin Cc: Arnd Bergmann Signed-off-by: Lada Trimasova [vgupta: beefed up changelog, added Fixes/stable tags] Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman --- arch/arc/include/asm/io.h | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) --- a/arch/arc/include/asm/io.h +++ b/arch/arc/include/asm/io.h @@ -129,15 +129,23 @@ static inline void __raw_writel(u32 w, v #define writel(v,c) ({ __iowmb(); writel_relaxed(v,c); }) /* - * Relaxed API for drivers which can handle any ordering themselves + * Relaxed API for drivers which can handle barrier ordering themselves + * + * Also these are defined to perform little endian accesses. + * To provide the typical device register semantics of fixed endian, + * swap the byte order for Big Endian + * + * http://lkml.kernel.org/r/201603100845.30602.arnd@arndb.de */ #define readb_relaxed(c) __raw_readb(c) -#define readw_relaxed(c) __raw_readw(c) -#define readl_relaxed(c) __raw_readl(c) +#define readw_relaxed(c) ({ u16 __r = le16_to_cpu((__force __le16) \ + __raw_readw(c)); __r; }) +#define readl_relaxed(c) ({ u32 __r = le32_to_cpu((__force __le32) \ + __raw_readl(c)); __r; }) #define writeb_relaxed(v,c) __raw_writeb(v,c) -#define writew_relaxed(v,c) __raw_writew(v,c) -#define writel_relaxed(v,c) __raw_writel(v,c) +#define writew_relaxed(v,c) __raw_writew((__force u16) cpu_to_le16(v),c) +#define writel_relaxed(v,c) __raw_writel((__force u32) cpu_to_le32(v),c) #include