Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752903AbcD2Axu (ORCPT ); Thu, 28 Apr 2016 20:53:50 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35761 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752625AbcD2Axm (ORCPT ); Thu, 28 Apr 2016 20:53:42 -0400 From: Christian Lamparter To: linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: =?UTF-8?q?=C3=81lvaro=20Fern=C3=A1ndez=20Rojas?= , Kumar Gala , Alexander Shiyan , Ian Campbell , Mark Rutland , Pawel Moll , Rob Herring , Alexandre Courbot , Linus Walleij , Christian Lamparter Subject: [RFC v5 4/4] gpio: dt-bindings: add gpio-mmio bindings Date: Fri, 29 Apr 2016 02:53:17 +0200 Message-Id: X-Mailer: git-send-email 2.8.1 In-Reply-To: References: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3477 Lines: 93 From: Álvaro Fernández Rojas This patch adds the device tree bindings for the gpio-mmio. The gpio-mmio is already part of a the GPIO generic library. Signed-off-by: Álvaro Fernández Rojas Signed-off-by: Christian Lamparter --- .../devicetree/bindings/gpio/gpio-mmio.txt | 73 ++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/gpio-mmio.txt diff --git a/Documentation/devicetree/bindings/gpio/gpio-mmio.txt b/Documentation/devicetree/bindings/gpio/gpio-mmio.txt new file mode 100644 index 0000000..cc7f0b1 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-mmio.txt @@ -0,0 +1,73 @@ +Bindings for the generic driver for memory-mapped GPIO controllers. + +Required properties: + - compatible: should be "linux,gpio-mmio" + - reg-names: must contain + "dat" - data register + may contain + "set" - data set register + "clr" - data clear register + "dirout" - direction output register + "dirin" - direction input register + - reg: address + size pairs describing the GPIO register sets; + order must correspond with the order of entries in reg-names + - #gpio-cells = must be set to 2 + - gpio-controller: Marks the device node as a gpio controller. + +Optional properties: + - ngpio: specifies the number of gpio mapped in the register. + - big-endian: force big endian register accesses. + - big-endian-byte-order: assign GPIOs in reverse order. + - unreadable-reg-set: data set register is not readable. + - read-output-reg-set: cache value set for reads. + - unreadable-reg-dir: dirout/dirin register is not readable. + - no-output: GPIOs are read-only. + +The GPIO generic library provides support for memory-mapped GPIO +controllers. The configuration is detected by which resources are present. +The simplest form of a GPIO controller that the driver support is just a +single "dat" register, where GPIO state can be read and/or written. +However, the driver supports far more: + - 8/16/32/64 bits registers. The number of GPIOs is automatically + determined by the width of the registers. + - GPIO controllers with clear/set registers. + - GPIO controllers with a single "dat" register. + - Big endian bits/GPIOs ordering. + +For setting GPIO's there are three configurations: + 1. single input/output register resource (named "dat"), + 2. set/clear pair (named "set" and "clr"), + 3. single output register resource and single input resource + ("set" and dat"). + +For setting the GPIO direction, there are three configurations: + a. simple bidirectional GPIOs that requires no configuration. + b. an output direction register (named "dirout") + where a 1 bit indicates the GPIO is an output. + c. an input direction register (named "dirin") + where a 1 bit indicates the GPIO is an input. + +Examples: + + /* Configuration for single input/output register + * for eight simple bidirectional GPIOs. + */ + gpio_a_1 { + compatible = "linux,gpio-mmio"; + reg = <0x18000000 0x1>; + reg-names = "dat"; + #gpio-cells = <2>; + gpio-controller; + }; + + /* Configuration for set/clear pair registers with + * 32 output direction register GPIOs. + */ + gpio_b_2 { + compatible = "linux,gpio-mmio"; + reg = <0x18000000 0x4>, <0x18000010 0x4>, + <0x18000004 0x4>, <0x18000008 0x4>; + reg-names = "dat", "set", "clr", "dirout"; + #gpio-cells = <2>; + gpio-controller; + }; -- 2.8.1