From patchwork Wed Jun 22 12:48:26 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geert Uytterhoeven X-Patchwork-Id: 9192703 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7E0A0601C0 for ; Wed, 22 Jun 2016 12:48:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6E6E4283E9 for ; Wed, 22 Jun 2016 12:48:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 634FC28402; Wed, 22 Jun 2016 12:48:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 35D84283E9 for ; Wed, 22 Jun 2016 12:48:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752445AbcFVMsh (ORCPT ); Wed, 22 Jun 2016 08:48:37 -0400 Received: from laurent.telenet-ops.be ([195.130.137.89]:42169 "EHLO laurent.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752141AbcFVMsg (ORCPT ); Wed, 22 Jun 2016 08:48:36 -0400 Received: from ayla.of.borg ([84.195.107.21]) by laurent.telenet-ops.be with bizsmtp id 9ooa1t00d0TjorY01ooaFr; Wed, 22 Jun 2016 14:48:35 +0200 Received: from ramsan.of.borg ([192.168.97.29] helo=ramsan) by ayla.of.borg with esmtp (Exim 4.82) (envelope-from ) id 1bFha6-0005Kc-T1; Wed, 22 Jun 2016 14:48:34 +0200 Received: from geert by ramsan with local (Exim 4.82) (envelope-from ) id 1bFha7-0000ka-HI; Wed, 22 Jun 2016 14:48:35 +0200 From: Geert Uytterhoeven To: Mark Brown Cc: linux-spi@vger.kernel.org, devicetree@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH] spi: Improve DT binding documentation Date: Wed, 22 Jun 2016 14:48:26 +0200 Message-Id: <1466599706-2850-1-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 1.9.1 Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP - Add missing verbs and periods, - Add spaces before opening parentheses, - Align list layout, - Correct grammar, - Move "cs-gpios" from the required to the optional properties section, - Remove spaces before tabs. Signed-off-by: Geert Uytterhoeven --- Documentation/devicetree/bindings/spi/spi-bus.txt | 35 ++++++++++++----------- 1 file changed, 18 insertions(+), 17 deletions(-) diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index 42d595425dfb9f3c..17822860cb98c34d 100644 --- a/Documentation/devicetree/bindings/spi/spi-bus.txt +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt @@ -8,11 +8,10 @@ in slave mode. The SPI master node requires the following properties: - #address-cells - number of cells required to define a chip select - address on the SPI bus. + address on the SPI bus. - #size-cells - should be zero. - compatible - name of SPI bus controller following generic names - recommended practice. -- cs-gpios - (optional) gpios chip select. + recommended practice. No other properties are required in the SPI bus node. It is assumed that a driver for an SPI bus device will understand that it is an SPI bus. However, the binding does not attempt to define the specific method for @@ -22,11 +21,12 @@ assumption that board specific platform code will be used to manage chip selects. Individual drivers can define additional properties to support describing the chip select layout. -Optional property: -- num-cs : total number of chipselects +Optional properties: +- cs-gpios - gpios chip select. +- num-cs - total number of chipselects. -If cs-gpios is used the number of chip select will automatically increased -with max(cs-gpios > hw cs) +If cs-gpios is used the number of chip selects will be increased automatically +with max(cs-gpios > hw cs). So if for example the controller has 2 CS lines, and the cs-gpios property looks like this: @@ -45,29 +45,30 @@ SPI slave nodes must be children of the SPI master node and can contain the following properties. - reg - (required) chip select address of device. - compatible - (required) name of SPI device following generic names - recommended practice -- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz + recommended practice. +- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz. - spi-cpol - (optional) Empty property indicating device requires - inverse clock polarity (CPOL) mode + inverse clock polarity (CPOL) mode. - spi-cpha - (optional) Empty property indicating device requires - shifted clock phase (CPHA) mode + shifted clock phase (CPHA) mode. - spi-cs-high - (optional) Empty property indicating device requires - chip select active high + chip select active high. - spi-3wire - (optional) Empty property indicating device requires - 3-wire mode. + 3-wire mode. - spi-lsb-first - (optional) Empty property indicating device requires LSB first mode. -- spi-tx-bus-width - (optional) The bus width(number of data wires) that +- spi-tx-bus-width - (optional) The bus width (number of data wires) that is used for MOSI. Defaults to 1 if not present. -- spi-rx-bus-width - (optional) The bus width(number of data wires) that +- spi-rx-bus-width - (optional) The bus width (number of data wires) that is used for MISO. Defaults to 1 if not present. - spi-rx-delay-us - (optional) Microsecond delay after a read transfer. - spi-tx-delay-us - (optional) Microsecond delay after a write transfer. Some SPI controllers and devices support Dual and Quad SPI transfer mode. -It allows data in the SPI system to be transferred in 2 wires(DUAL) or 4 wires(QUAD). +It allows data in the SPI system to be transferred using 2 wires (DUAL) or 4 +wires (QUAD). Now the value that spi-tx-bus-width and spi-rx-bus-width can receive is -only 1(SINGLE), 2(DUAL) and 4(QUAD). +only 1 (SINGLE), 2 (DUAL) and 4 (QUAD). Dual/Quad mode is not allowed when 3-wire mode is used. If a gpio chipselect is used for the SPI slave the gpio number will be passed