From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753325AbbDFORS (ORCPT ); Mon, 6 Apr 2015 10:17:18 -0400 Received: from mga03.intel.com ([134.134.136.65]:61090 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753292AbbDFORN (ORCPT ); Mon, 6 Apr 2015 10:17:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,532,1422950400"; d="scan'208";a="690931619" From: Daniel Baluta To: jic23@kernel.org Cc: jlbec@evilplan.org, lars@metafoo.de, knaack.h@gmx.de, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, octavian.purdila@intel.com, daniel.baluta@intel.com, pebolle@tiscali.nl, patrick.porlan@intel.com, adriana.reus@intel.com Subject: [PATCH v3 3/3] iio: Documentation: Add documentation for IIO configfs Date: Mon, 6 Apr 2015 17:18:09 +0300 Message-Id: <1428329889-18335-4-git-send-email-daniel.baluta@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1428329889-18335-1-git-send-email-daniel.baluta@intel.com> References: <1428329889-18335-1-git-send-email-daniel.baluta@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Daniel Baluta --- Changes since v2: * fix some whitespace issues reported by Paul Changes since v1: * addressed feedback for v1: * https://lkml.org/lkml/2015/3/25/648 * adapted to match the changes in patches 1 and 2 * fixed some typos and clarified further work Documentation/iio/iio_configfs.txt | 83 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 Documentation/iio/iio_configfs.txt diff --git a/Documentation/iio/iio_configfs.txt b/Documentation/iio/iio_configfs.txt new file mode 100644 index 0000000..ace7b54 --- /dev/null +++ b/Documentation/iio/iio_configfs.txt @@ -0,0 +1,83 @@ +Industrial IIO configfs support + +1. Overview + +Configfs is a filesystem-based manager of kernel objects. IIO uses some +objects that could be easily configured using configfs (e.g.: devices, +triggers). + +See Documentation/filesystems/configfs/configfs.txt for more information +about how configfs works. + +2. Usage + +In order to use configfs support in IIO we need to select it at compile +time via CONFIG_IIO_CONFIGFS config option. + +Then, mount the configfs filesystem (usually under /config directory): + +$ mkdir /config +$ mount -t configfs none /config + +At this point, all default IIO groups will be created and can be accessed +under /config/iio. Next chapters will describe available IIO configuration +objects. + +3. Software triggers + +One of the IIO default configfs groups is the "triggers" groups. It is +automagically accessible when the configfs is mounted and can be found +under /config/iio/triggers. + +Under /config/iio/triggers we will create trigger types. For the moment +we have "hrtimer" trigger type and we plan to add at least one more type, +the "sysfs" trigger type. + +3.1 Trigger types + +Represent a specific type of trigger. For now we have an implementation +for "hrtimer" trigger type. + +3.2. Trigger creation and destruction + +As simply as: + +$ mkdir /config/triggers/hrtimer/my_trigger + +Creating my_trigger directory will result in creation of "my_trigger" +trigger of "hrtimer" type. Destruction happens when my_trigger directory +is removed. + +Each trigger can have one or more attributes specific to the trigger type. + +3.3 "hrtimer" trigger types attributes + +"hrtimer" trigger type has only one attribute: + +$ ls /config/triggers/hrtimer/my_trigger +delay + +delay - represents the amount of time in nanoseconds between two +consecutive iio_trigger_poll calls. By default it is set to 100000000, +that is the equivalent of a 100Hz frequency. + +3.4. Adding a new trigger type + +In order to add a new trigger type, one needs to: + +* [iio_configfs_trigger.h] + ** add a new IIO_TRIGGER_TYPE +* [iio-trig-.c] + ** declare and initialize a structure of type + iio_configfs_trigger_type + ** implement needed iio_configfs_trigger_ops + ** register/unregister the new trigger + type with the IIO configfs core +* [industrialiio-configfs.c] + ** create a new group type and add it in the default group of + trigger types. + ** create new attributes and them to the IIO configfs core. + +4. Further work + +* add "sysfs" trigger type -- 1.9.1