From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 12 Nov 2014 09:48:02 +0100 (CET) Received: from mail-pd0-f169.google.com ([209.85.192.169]:48884 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S27013472AbaKLIrQC8bxf (ORCPT ); Wed, 12 Nov 2014 09:47:16 +0100 Received: by mail-pd0-f169.google.com with SMTP id y10so11809998pdj.28 for ; Wed, 12 Nov 2014 00:47:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Z9ywekGBNsO2qB+SdZz9Dzbt3UhG15wGQaf3pQ6XGug=; b=TbqTnq4w4Fniek42ZOiGFChCO0H8iP+yJWH2k8+odePagKx1rbrnbW0Vcn2DvU1Rsf rdxN20L1hW3GYS1DTeVHhEZcVD7iqK6thcUQhGbeY4gAAEsw9DGHWDXU9f+bPOPnrAy2 XxLXOeRKH2YmC5IvgHEAabTwVUFQr0XIQf/NEd3SeYTpGw9swmAAsWmguvWH3H6ojgo+ XmpuwNXX9/CeamKpU/mZDO2hML//slnw/zgqK5h6PkMYAah/cYoOvnZqfZflAHJZ3vTY 3yYmu+4llFMFJNdqpDPbbo/Eab9wnDtw8k25rCGocRwT8VUC23VT8Hu2LcCmsgVDwlO8 fx0g== X-Received: by 10.70.2.65 with SMTP id 1mr46430553pds.13.1415782030001; Wed, 12 Nov 2014 00:47:10 -0800 (PST) Received: from localhost (b32.net. [192.81.132.72]) by mx.google.com with ESMTPSA id p10sm18804833pds.63.2014.11.12.00.47.08 for (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 12 Nov 2014 00:47:09 -0800 (PST) From: Kevin Cernekee To: gregkh@linuxfoundation.org, jslaby@suse.cz, robh@kernel.org Cc: tushar.behera@linaro.org, daniel@zonque.org, haojian.zhuang@gmail.com, robert.jarzmik@free.fr, grant.likely@linaro.org, f.fainelli@gmail.com, mbizon@freebox.fr, jogo@openwrt.org, linux-mips@linux-mips.org, linux-serial@vger.kernel.org, devicetree@vger.kernel.org Subject: [PATCH/RFC 3/8] of: Add helper function to check MMIO register endianness Date: Wed, 12 Nov 2014 00:46:28 -0800 Message-Id: <1415781993-7755-4-git-send-email-cernekee@gmail.com> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1415781993-7755-1-git-send-email-cernekee@gmail.com> References: <1415781993-7755-1-git-send-email-cernekee@gmail.com> Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 44031 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: cernekee@gmail.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips SoC peripherals can come in several different flavors: - little-endian: registers always need to be accessed in LE mode (so the kernel should perform a swap if the CPU is running BE) - big-endian: registers always need to be accessed in BE mode (so the kernel should perform a swap if the CPU is running LE) - native-endian: the bus will automatically swap accesses, so the kernel should never swap Introduce a function that checks an OF device node to see whether it contains a "big-endian" or "native-endian" property. For the former case, always return 1. For the latter case, return 1 iff the kernel was built for BE (implying that the BE MMIO accessors do not perform a swap). Otherwise return 0, assuming LE registers. LE registers are assumed by default because most existing drivers (libahci, serial8250, usb) always use readl/writel in the absence of instructions to the contrary, so that will be our fallback. Signed-off-by: Kevin Cernekee --- drivers/of/base.c | 23 +++++++++++++++++++++++ include/linux/of.h | 6 ++++++ 2 files changed, 29 insertions(+) diff --git a/drivers/of/base.c b/drivers/of/base.c index 3823edf..9dd494a 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -552,6 +552,29 @@ int of_device_is_available(const struct device_node *device) EXPORT_SYMBOL(of_device_is_available); /** + * of_device_is_big_endian - check if a device has BE registers + * + * @device: Node to check for availability + * + * Returns 1 if the device has a "big-endian" property, or if the kernel + * was compiled for BE *and* the device has a "native-endian" property. + * Returns 0 otherwise. + * + * Callers would nominally use ioread32be/iowrite32be if + * of_device_is_big_endian() == 1, or readl/writel otherwise. + */ +int of_device_is_big_endian(const struct device_node *device) +{ + if (of_property_read_bool(device, "big-endian")) + return 1; + if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) && + of_property_read_bool(device, "native-endian")) + return 1; + return 0; +} +EXPORT_SYMBOL(of_device_is_big_endian); + +/** * of_get_parent - Get a node's parent if any * @node: Node to get parent * diff --git a/include/linux/of.h b/include/linux/of.h index 29f0adc..d24ccf3 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -276,6 +276,7 @@ extern int of_property_read_string_helper(struct device_node *np, extern int of_device_is_compatible(const struct device_node *device, const char *); extern int of_device_is_available(const struct device_node *device); +extern int of_device_is_big_endian(const struct device_node *device); extern const void *of_get_property(const struct device_node *node, const char *name, int *lenp); @@ -431,6 +432,11 @@ static inline int of_device_is_available(const struct device_node *device) return 0; } +static inline int of_device_is_big_endian(const struct device_node *device) +{ + return 0; +} + static inline struct property *of_find_property(const struct device_node *np, const char *name, int *lenp) -- 2.1.1