From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52F45C38A2A for ; Fri, 8 May 2020 13:55:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3749520708 for ; Fri, 8 May 2020 13:55:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728682AbgEHNzJ (ORCPT ); Fri, 8 May 2020 09:55:09 -0400 Received: from mx0a-00128a01.pphosted.com ([148.163.135.77]:42472 "EHLO mx0a-00128a01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727092AbgEHNyO (ORCPT ); Fri, 8 May 2020 09:54:14 -0400 Received: from pps.filterd (m0167089.ppops.net [127.0.0.1]) by mx0a-00128a01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 048Dr3v9016945; Fri, 8 May 2020 09:54:03 -0400 Received: from nwd2mta4.analog.com ([137.71.173.58]) by mx0a-00128a01.pphosted.com with ESMTP id 30vtek2gcn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 08 May 2020 09:54:02 -0400 Received: from ASHBMBX9.ad.analog.com (ashbmbx9.ad.analog.com [10.64.17.10]) by nwd2mta4.analog.com (8.14.7/8.14.7) with ESMTP id 048Ds1Cv040822 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=FAIL); Fri, 8 May 2020 09:54:01 -0400 Received: from ASHBMBX9.ad.analog.com (10.64.17.10) by ASHBMBX9.ad.analog.com (10.64.17.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1779.2; Fri, 8 May 2020 09:54:00 -0400 Received: from zeus.spd.analog.com (10.64.82.11) by ASHBMBX9.ad.analog.com (10.64.17.10) with Microsoft SMTP Server id 15.1.1779.2 via Frontend Transport; Fri, 8 May 2020 09:54:00 -0400 Received: from localhost.localdomain ([10.48.65.12]) by zeus.spd.analog.com (8.15.1/8.15.1) with ESMTP id 048Drpwp030263; Fri, 8 May 2020 09:53:58 -0400 From: Alexandru Ardelean To: , CC: , , Alexandru Ardelean Subject: [RFC PATCH 05/14] iio: core: register chardev only if needed Date: Fri, 8 May 2020 16:53:39 +0300 Message-ID: <20200508135348.15229-6-alexandru.ardelean@analog.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200508135348.15229-1-alexandru.ardelean@analog.com> References: <20200508135348.15229-1-alexandru.ardelean@analog.com> MIME-Version: 1.0 Content-Type: text/plain X-ADIRoutedOnPrem: True X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.676 definitions=2020-05-08_13:2020-05-08,2020-05-08 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=999 lowpriorityscore=0 phishscore=0 clxscore=1015 mlxscore=0 bulkscore=0 malwarescore=0 suspectscore=2 adultscore=0 spamscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005080123 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The final intent is to localize all buffer ops into the industrialio-buffer.c file, to be able to add support for multiple buffers per IIO device. We only need a chardev if we need to support buffers and/or events. With this change, a chardev will be created only if an IIO buffer is attached OR an event_interface is configured. Otherwise, no chardev will be created, and the IIO device will get registered with the 'device_add()' call. Quite a lot of IIO devices don't really need a chardev, so this is a minor improvement to the IIO core, as the IIO device will take up (slightly) fewer resources. What's important to remember, is that removing a chardev also requires that 'indio_dev->dev.devt' to be initialized. If it is, a '/dev/iio:deviceX' file will be created by the kernel, regardless of whether it has a chardev attached to it or not. If that field is not initialized, cdev_device_{add,del}() behave{s} like device_{add,del}(). Also, since we plan to add more chardevs for IIO buffers, we need to consider now a separate IDA object just for chardevs. Currently, the only benefit is that chardev IDs will be continuous. However, when adding a chardev per IIO buffer, the IDs for the chardev could outpace the IDs for IIO devices, so these should be decoupled. Signed-off-by: Alexandru Ardelean --- drivers/iio/industrialio-core.c | 58 +++++++++++++++++++++++++++++---- 1 file changed, 51 insertions(+), 7 deletions(-) diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 32c489139cd2..d74279efeca4 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -35,6 +35,9 @@ /* IDA to assign each registered device a unique id */ static DEFINE_IDA(iio_ida); +/* IDA to assign each registered character device a unique id */ +static DEFINE_IDA(iio_chrdev_ida); + static dev_t iio_devt; #define IIO_DEV_MAX 256 @@ -1680,8 +1683,40 @@ static int iio_check_unique_scan_index(struct iio_dev *indio_dev) return 0; } +static int iio_device_alloc_chrdev_id(struct device *dev) +{ + int id; + + id = ida_simple_get(&iio_chrdev_ida, 0, 0, GFP_KERNEL); + if (id < 0) { + /* cannot use a dev_err as the name isn't available */ + dev_err(dev, "failed to get device id\n"); + return id; + } + + dev->devt = MKDEV(MAJOR(iio_devt), id); + + return 0; +} + +static void iio_device_free_chrdev_id(struct device *dev) +{ + if (!dev->devt) + return; + ida_simple_remove(&iio_chrdev_ida, MINOR(dev->devt)); +} + static const struct iio_buffer_setup_ops noop_ring_setup_ops; +static const struct file_operations iio_event_fileops = { + .owner = THIS_MODULE, + .llseek = noop_llseek, + .unlocked_ioctl = iio_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .open = iio_chrdev_open, + .release = iio_chrdev_release, +}; + int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod) { int ret; @@ -1701,9 +1736,6 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod) if (ret < 0) return ret; - /* configure elements for the chrdev */ - indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id); - iio_device_register_debugfs(indio_dev); ret = iio_buffer_alloc_sysfs_and_mask(indio_dev); @@ -1732,16 +1764,27 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod) indio_dev->setup_ops == NULL) indio_dev->setup_ops = &noop_ring_setup_ops; - cdev_init(&indio_dev->chrdev, &iio_buffer_fileops); + if (indio_dev->buffer) + cdev_init(&indio_dev->chrdev, &iio_buffer_fileops); + else if (indio_dev->event_interface) + cdev_init(&indio_dev->chrdev, &iio_event_fileops); - indio_dev->chrdev.owner = this_mod; + if (indio_dev->buffer || indio_dev->event_interface) { + indio_dev->chrdev.owner = this_mod; + + ret = iio_device_alloc_chrdev_id(&indio_dev->dev); + if (ret) + goto error_unreg_eventset; + } ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev); - if (ret < 0) - goto error_unreg_eventset; + if (ret) + goto error_free_chrdev_id; return 0; +error_free_chrdev_id: + iio_device_free_chrdev_id(&indio_dev->dev); error_unreg_eventset: iio_device_unregister_eventset(indio_dev); error_free_sysfs: @@ -1761,6 +1804,7 @@ EXPORT_SYMBOL(__iio_device_register); void iio_device_unregister(struct iio_dev *indio_dev) { cdev_device_del(&indio_dev->chrdev, &indio_dev->dev); + iio_device_free_chrdev_id(&indio_dev->dev); mutex_lock(&indio_dev->info_exist_lock); -- 2.17.1