From patchwork Wed Nov 16 14:29:09 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shuah Khan X-Patchwork-Id: 9432373 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 868CC60471 for ; Wed, 16 Nov 2016 18:40:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7987828490 for ; Wed, 16 Nov 2016 18:40:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6D81428675; Wed, 16 Nov 2016 18:40:19 +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=-1.4 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM autolearn=no version=3.3.1 Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C4F8928490 for ; Wed, 16 Nov 2016 18:40:17 +0000 (UTC) Received: by alsa0.perex.cz (Postfix, from userid 1000) id D9134267465; Wed, 16 Nov 2016 19:40:15 +0100 (CET) Received: from alsa0.perex.cz (localhost [127.0.0.1]) by alsa0.perex.cz (Postfix) with ESMTP id 84636266D07; Wed, 16 Nov 2016 19:37:50 +0100 (CET) X-Original-To: alsa-devel@alsa-project.org Delivered-To: alsa-devel@alsa-project.org Received: by alsa0.perex.cz (Postfix, from userid 1000) id B4EDA266D33; Wed, 16 Nov 2016 15:29:29 +0100 (CET) Received: from resqmta-po-09v.sys.comcast.net (resqmta-po-09v.sys.comcast.net [96.114.154.168]) by alsa0.perex.cz (Postfix) with ESMTP id 5A097266D4E for ; Wed, 16 Nov 2016 15:29:19 +0100 (CET) Received: from resomta-po-04v.sys.comcast.net ([96.114.154.228]) by resqmta-po-09v.sys.comcast.net with SMTP id 71D2cyvWqS0FE71DBc3asr; Wed, 16 Nov 2016 14:29:17 +0000 Received: from mail.gonehiking.org ([73.181.52.62]) by resomta-po-04v.sys.comcast.net with SMTP id 71D9c8y00DCnG71D9cwn8m; Wed, 16 Nov 2016 14:29:17 +0000 Received: from localhost.localdomain (shuah-xps.internal [192.168.1.87]) by mail.gonehiking.org (Postfix) with ESMTP id ABB499F4D8; Wed, 16 Nov 2016 07:29:14 -0700 (MST) From: Shuah Khan To: mchehab@kernel.org, perex@perex.cz, tiwai@suse.com, hans.verkuil@cisco.com, javier@osg.samsung.com, chehabrafael@gmail.com, g.liakhovetski@gmx.de, ONeukum@suse.com, k@oikw.org, daniel@zonque.org, mahasler@gmail.com, clemens@ladisch.de, geliangtang@163.com, vdronov@redhat.com, laurent.pinchart@ideasonboard.com Date: Wed, 16 Nov 2016 07:29:09 -0700 Message-Id: <448169cd2db0ba7c8a455bd672e6709e6bada2aa.1479271294.git.shuahkh@osg.samsung.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: References: In-Reply-To: References: X-CMAE-Envelope: MS4wfO/T+3AKrmNLE5bxCCizYZJemz5u/l0ZhRuaBrwH+aJw7jO110SBJLvZv1S40ZAXkR0d+7oP9kuV6fFmsX5oqw8WSaoa9jr8eKHgW6UmgZSBgyTXMq4p hLRP7IoRmU2UVPbLbnME7HN+G84xw+NKJ3DzFjd03CstJBhcD6YYve+pSenRyFWhQ9+wO5+lavz5fKclv6M2ezpRlAjB0g5bLbjNPgj6Ncb3Y09MA5eJ8q7D mCcOlMAKja9Zq1ahNPZsIULGXT3bpl0RXX9fSOPdeS8bX0hBhvkW6Ut4IIyzt8L+kCGvOpZLSMugtIcj9FjniERdqsWZNB8xcD+hgp29kpz8ZOhRAYmBp7lN iZDlE0/QFT9shrkuVGHlil7UuPrdU3q2/D1BqPFxaqhac1GtNs/r9byJZsEd5aEBnGEv9CLLcMfy5och6+GBdtGPHL7IQydYgwpwrkdI/+w+w535YQJMIVOf IY6gGlXuwz8x7wNF+i/geWV4WSD+sDDQRf1XeZxuz+X5Jfh4F8Hwi6U0JE23iqhdRtKpskD9Iahs3H14etJ9u3iJFnT5Z0MLwgLUWcka8qktaRutIClNnPJo rPNX5YYSjfyjWC8S1IR5gzS9QS8ijM+MxyuYkQPvYR+/WZzVMwsRuo+MbOsodV5rHYRqs6B5kSgA+Ad9WkQ21o7e+nAfHr7CIH154zs2x+d+eSfQJ9425KVw IqcW7zkQZB6q6PQKffO4ofYCo+YBQe6p0Ma2spTu9kXz5WP6BhYC9g== Cc: alsa-devel@alsa-project.org, linux-media@vger.kernel.org, Shuah Khan , linux-kernel@vger.kernel.org Subject: [alsa-devel] [PATCH v4 1/3] media: Media Device Allocator API X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org X-Virus-Scanned: ClamAV using ClamSMTP Media Device Allocator API to allows multiple drivers share a media device. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released. Signed-off-by: Shuah Khan Reviewed-by: Hans Verkuil --- Changes since v3: - Fixed undefined reference to `__media_device_usb_init compile error when CONFIG_USB is disabled. - Fixed kernel paging error when accessing /dev/mediaX after rmmod of the module that owns the media_device. The fix bumps the reference count for the owner when second driver comes along to share the media_device. If au0828 owns the media_device, then snd_usb_audio will bump the refcount for au0828, so it won't get deleted and vice versa. drivers/media/Makefile | 3 +- drivers/media/media-dev-allocator.c | 146 ++++++++++++++++++++++++++++++++++++ include/media/media-dev-allocator.h | 87 +++++++++++++++++++++ 3 files changed, 235 insertions(+), 1 deletion(-) create mode 100644 drivers/media/media-dev-allocator.c create mode 100644 include/media/media-dev-allocator.h diff --git a/drivers/media/Makefile b/drivers/media/Makefile index 0deaa93..7c0701d 100644 --- a/drivers/media/Makefile +++ b/drivers/media/Makefile @@ -6,7 +6,8 @@ ifeq ($(CONFIG_MEDIA_CEC_EDID),y) obj-$(CONFIG_MEDIA_SUPPORT) += cec-edid.o endif -media-objs := media-device.o media-devnode.o media-entity.o +media-objs := media-device.o media-devnode.o media-entity.o \ + media-dev-allocator.o # # I2C drivers should come before other drivers, otherwise they'll fail diff --git a/drivers/media/media-dev-allocator.c b/drivers/media/media-dev-allocator.c new file mode 100644 index 0000000..014a317 --- /dev/null +++ b/drivers/media/media-dev-allocator.c @@ -0,0 +1,146 @@ +/* + * media-dev-allocator.c - Media Controller Device Allocator API + * + * Copyright (c) 2016 Shuah Khan + * Copyright (c) 2016 Samsung Electronics Co., Ltd. + * + * This file is released under the GPLv2. + * Credits: Suggested by Laurent Pinchart + */ + +/* + * This file adds a global refcounted Media Controller Device Instance API. + * A system wide global media device list is managed and each media device + * includes a kref count. The last put on the media device releases the media + * device instance. + * + */ + +#include +#include +#include +#include +#include + +static LIST_HEAD(media_device_list); +static DEFINE_MUTEX(media_device_lock); + +struct media_device_instance { + struct media_device mdev; + struct module *owner; + struct list_head list; + struct device *dev; + struct kref refcount; +}; + +static inline struct media_device_instance * +to_media_device_instance(struct media_device *mdev) +{ + return container_of(mdev, struct media_device_instance, mdev); +} + +static void media_device_instance_release(struct kref *kref) +{ + struct media_device_instance *mdi = + container_of(kref, struct media_device_instance, refcount); + + dev_dbg(mdi->mdev.dev, "%s: mdev=%p\n", __func__, &mdi->mdev); + + mutex_lock(&media_device_lock); + + media_device_unregister(&mdi->mdev); + media_device_cleanup(&mdi->mdev); + + list_del(&mdi->list); + mutex_unlock(&media_device_lock); + + kfree(mdi); +} + +/* Callers should hold media_device_lock when calling this function */ +static struct media_device *__media_device_get(struct device *dev, + char *module_name) +{ + struct media_device_instance *mdi; + + list_for_each_entry(mdi, &media_device_list, list) { + if (mdi->dev == dev) { + kref_get(&mdi->refcount); + /* get module reference for the media_device owner */ + if (find_module(module_name) != mdi->owner && + !try_module_get(mdi->owner)) + dev_err(dev, "%s: try_module_get() error\n", + __func__); + dev_dbg(dev, "%s: get mdev=%p module_name %s\n", + __func__, &mdi->mdev, module_name); + return &mdi->mdev; + } + } + + mdi = kzalloc(sizeof(*mdi), GFP_KERNEL); + if (!mdi) + return NULL; + + mdi->dev = dev; + mdi->owner = find_module(module_name); + kref_init(&mdi->refcount); + list_add_tail(&mdi->list, &media_device_list); + + dev_dbg(dev, "%s: alloc mdev=%p module_name %s\n", __func__, + &mdi->mdev, module_name); + return &mdi->mdev; +} + +#if IS_ENABLED(CONFIG_USB) +struct media_device *media_device_usb_allocate(struct usb_device *udev, + char *module_name) +{ + struct media_device *mdev; + + if (!module_name) { + dev_err(&udev->dev, "%s Module Name is null\n", __func__); + return ERR_PTR(-EINVAL); + } + + mutex_lock(&media_device_lock); + mdev = __media_device_get(&udev->dev, module_name); + if (!mdev) { + mutex_unlock(&media_device_lock); + return ERR_PTR(-ENOMEM); + } + + /* check if media device is already initialized */ + if (!mdev->dev) + __media_device_usb_init(mdev, udev, udev->product, + module_name); + mutex_unlock(&media_device_lock); + + dev_dbg(&udev->dev, "%s\n", __func__); + return mdev; +} +EXPORT_SYMBOL_GPL(media_device_usb_allocate); +#endif + +void media_device_delete(struct media_device *mdev, char *module_name) +{ + struct media_device_instance *mdi = to_media_device_instance(mdev); + + if (!module_name) { + dev_err(mdi->mdev.dev, "%s Module Name is null\n", __func__); + return; + } + + dev_dbg(mdi->mdev.dev, "%s: mdev=%p module_name %s\n", + __func__, &mdi->mdev, module_name); + + mutex_lock(&media_device_lock); + /* put module reference if media_device owner is not THIS_MODULE */ + if (mdi->owner != find_module(module_name)) { + module_put(mdi->owner); + dev_dbg(mdi->mdev.dev, + "%s decremented owner module reference\n", __func__); + } + mutex_unlock(&media_device_lock); + kref_put(&mdi->refcount, media_device_instance_release); +} +EXPORT_SYMBOL_GPL(media_device_delete); diff --git a/include/media/media-dev-allocator.h b/include/media/media-dev-allocator.h new file mode 100644 index 0000000..45c437d --- /dev/null +++ b/include/media/media-dev-allocator.h @@ -0,0 +1,87 @@ +/* + * media-dev-allocator.h - Media Controller Device Allocator API + * + * Copyright (c) 2016 Shuah Khan + * Copyright (c) 2016 Samsung Electronics Co., Ltd. + * + * This file is released under the GPLv2. + * Credits: Suggested by Laurent Pinchart + */ + +/* + * This file adds a global ref-counted Media Controller Device Instance API. + * A system wide global media device list is managed and each media device + * includes a kref count. The last put on the media device releases the media + * device instance. + */ + +#ifndef _MEDIA_DEV_ALLOCTOR_H +#define _MEDIA_DEV_ALLOCTOR_H + +struct usb_device; + +#ifdef CONFIG_MEDIA_CONTROLLER +/** + * DOC: Media Controller Device Allocator API + * + * When media device belongs to more than one driver, the shared media device + * is allocated with the shared struct device as the key for look ups. + * + * Shared media device should stay in registered state until the last driver + * unregisters it. In addition, media device should be released when all the + * references are released. Each driver gets a reference to the media device + * during probe, when it allocates the media device. If media device is already + * allocated, allocate API bumps up the refcount and return the existing media + * device. Driver puts the reference back from its disconnect routine when it + * calls media_device_delete(). + * + * Media device is unregistered and cleaned up from the kref put handler to + * ensure that the media device stays in registered state until the last driver + * unregisters the media device. + * + * Driver Usage: + * + * Drivers should use the media-core routines to get register reference and + * call media_device_delete() routine to make sure the shared media device + * delete is handled correctly. + * + * driver probe: + * Call media_device_usb_allocate() to allocate or get a reference + * Call media_device_register(), if media devnode isn't registered + * + * driver disconnect: + * Call media_device_delete() to free the media_device. Free'ing is + * handled by the put handler. + * + */ + +/** + * media_device_usb_allocate() - Allocate and return media device + * + * @udev - struct usb_device pointer + * @module_name + * + * This interface should be called to allocate a media device when multiple + * drivers share usb_device and the media device. This interface allocates + * media device and calls media_device_usb_init() to initialize it. + * + */ +struct media_device *media_device_usb_allocate(struct usb_device *udev, + char *module_name); +/** + * media_device_delete() - Release media device. Calls kref_put(). + * + * @mdev - struct media_device pointer + * @module_name + * + * This interface should be called to put Media Device Instance kref. + */ +void media_device_delete(struct media_device *mdev, char *driver_name); +#else +static inline struct media_device *media_device_usb_allocate( + struct usb_device *udev, char *driver_name) + { return NULL; } +static inline void media_device_delete( + struct media_device *mdev, char *module_name) { } +#endif /* CONFIG_MEDIA_CONTROLLER */ +#endif