From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934009AbcCITaX (ORCPT ); Wed, 9 Mar 2016 14:30:23 -0500 Received: from mail-pf0-f193.google.com ([209.85.192.193]:35386 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933251AbcCITaT (ORCPT ); Wed, 9 Mar 2016 14:30:19 -0500 From: Alison Schofield To: outreachy-kernel@googlegroups.com Cc: jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Michael.Hennerich@analog.com, gregkh@linuxfoundation.org, devel@driverdev.osuosl.org Subject: [RFC PATCH v2 1/2] iio: core: implement iio_device_{claim|release}_direct_mode() Date: Wed, 9 Mar 2016 11:30:12 -0800 Message-Id: X-Mailer: git-send-email 2.1.4 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is often the case that the driver wants to be sure a device stays in direct mode while it is executing a task or series of tasks. To accomplish this today, the driver performs this sequence: 1) take the device state lock, 2) verify it is not in a buffered mode, 3) execute some tasks, and 4) release that lock. This patch introduces a pair of helper functions that simplify these steps and make it more semantically expressive. iio_device_claim_direct_mode() If the device is not in any buffered mode it is guaranteed to stay that way until iio_release_direct_mode() is called. iio_device_release_direct_mode() Release the claim. Device is no longer guaranteed to stay in direct mode. Signed-off-by: Alison Schofield --- drivers/iio/industrialio-core.c | 39 +++++++++++++++++++++++++++++++++++++++ include/linux/iio/iio.h | 2 ++ 2 files changed, 41 insertions(+) diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 70cb7eb..2e768bc 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include "iio_core.h" #include "iio_core_trigger.h" @@ -1375,6 +1376,44 @@ void devm_iio_device_unregister(struct device *dev, struct iio_dev *indio_dev) } EXPORT_SYMBOL_GPL(devm_iio_device_unregister); +/** + * iio_device_claim_direct_mode - Keep device in direct mode + * @indio_dev: the iio_dev associated with the device + * + * If the device is in direct mode it is guaranteed to stay + * that way until iio_device_release_direct_mode() is called. + * + * Use with iio_device_release_direct_mode() + * + * Returns: 0 on success, -EBUSY on failure + */ +int iio_device_claim_direct_mode(struct iio_dev *indio_dev) +{ + mutex_lock(&indio_dev->mlock); + + if (iio_buffer_enabled(indio_dev)) { + mutex_unlock(&indio_dev->mlock); + return -EBUSY; + } + return 0; +} +EXPORT_SYMBOL_GPL(iio_device_claim_direct_mode); + +/** + * iio_device_release_direct_mode - releases claim on direct mode + * @indio_dev: the iio_dev associated with the device + * + * Release the claim. Device is no longer guaranteed to stay + * in direct mode. + * + * Use with iio_device_claim_direct_mode() + */ +void iio_device_release_direct_mode(struct iio_dev *indio_dev) +{ + mutex_unlock(&indio_dev->mlock); +} +EXPORT_SYMBOL_GPL(iio_device_release_direct_mode); + subsys_initcall(iio_init); module_exit(iio_exit); diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index b2b1677..0b2773a 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -527,6 +527,8 @@ void iio_device_unregister(struct iio_dev *indio_dev); int devm_iio_device_register(struct device *dev, struct iio_dev *indio_dev); void devm_iio_device_unregister(struct device *dev, struct iio_dev *indio_dev); int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp); +int iio_device_claim_direct_mode(struct iio_dev *indio_dev); +void iio_device_release_direct_mode(struct iio_dev *indio_dev); extern struct bus_type iio_bus_type; -- 2.1.4