| Message ID | 075f607f991d5dc0468cec69d67c2767f3a4e1cb.1479502501.git.shuahkh@osg.samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Em Fri, 18 Nov 2016 14:45:10 -0700 Shuah Khan <shuahkh@osg.samsung.com> escreveu: > 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 <shuahkh@osg.samsung.com> > Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com> > --- > Changes to patch 0001 since v4: > - Addressed Sakari's review comments with the exception of > opting to not introduce media_device_usb_allocate() macro, > and to not add a new routine to find media device instance > to avoid a one line check. > > Documentation/media/kapi/mc-core.rst | 2 + > drivers/media/Makefile | 3 +- > drivers/media/media-dev-allocator.c | 135 +++++++++++++++++++++++++++++++++++ > include/media/media-dev-allocator.h | 88 +++++++++++++++++++++++ > 4 files changed, 227 insertions(+), 1 deletion(-) > create mode 100644 drivers/media/media-dev-allocator.c > create mode 100644 include/media/media-dev-allocator.h > > diff --git a/Documentation/media/kapi/mc-core.rst b/Documentation/media/kapi/mc-core.rst > index 1a738e5..0b9090d 100644 > --- a/Documentation/media/kapi/mc-core.rst > +++ b/Documentation/media/kapi/mc-core.rst > @@ -262,3 +262,5 @@ in the end provide a way to use driver-specific callbacks. > .. kernel-doc:: include/media/media-devnode.h > > .. kernel-doc:: include/media/media-entity.h > + > +.. kernel-doc:: 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..581e50e > --- /dev/null > +++ b/drivers/media/media-dev-allocator.c > @@ -0,0 +1,135 @@ > +/* > + * media-dev-allocator.c - Media Controller Device Allocator API > + * > + * Copyright (c) 2016 Shuah Khan <shuahkh@osg.samsung.com> > + * Copyright (c) 2016 Samsung Electronics Co., Ltd. > + * > + * This file is released under the GPLv2. > + * Credits: Suggested by Laurent Pinchart <laurent.pinchart@ideasonboard.com> > + */ > + > +/* > + * 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 <linux/kref.h> > +#include <linux/module.h> > +#include <linux/slab.h> > +#include <linux/usb.h> > + > +#include <media/media-device.h> > + > +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; I agree with Sakari here: mdev is embedded. So, it will always have a mdev.dev inside it. So, if dev == mdev.dev for all cases, we can just get rid of it. If you want to simplify the code, just add a to_dev() macro like: #define to_dev(mdi) (mdi)->mdev.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) > + continue; > + > + 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; > + > + 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); It misses variant for PCI drivers. Ok, we could postpone it until we have the need of using media device allocator on pci drivers. > + mutex_unlock(&media_device_lock); > + 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); > + > + 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..fad8cb9 > --- /dev/null > +++ b/include/media/media-dev-allocator.h > @@ -0,0 +1,88 @@ > +/* > + * media-dev-allocator.h - Media Controller Device Allocator API > + * > + * Copyright (c) 2016 Shuah Khan <shuahkh@osg.samsung.com> > + * Copyright (c) 2016 Samsung Electronics Co., Ltd. > + * > + * This file is released under the GPLv2. > + * Credits: Suggested by Laurent Pinchart <laurent.pinchart@ideasonboard.com> > + */ > + > +/* > + * 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 > +/** > + * Media Controller Device Allocator API Huh? kernel-doc won't work with this. Did you test this patch with the media documentation, by calling: make DOCBOOKS="" SPHINXOPTS="-j9" SPHINXDIRS=media htmldocs Also, as I said before: please move those textual descriptions to Documentation/media/kapi/mc-core.rst, and use ReST markup to enrich it and add cross-references to functions and data structs mentioned below. > + * > + * 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: should be filled with KBUILD_MODNAME > + * > + * 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 structure 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: should be filled with KBUILD_MODNAME > + * > + * 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 Thanks, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/media/kapi/mc-core.rst b/Documentation/media/kapi/mc-core.rst index 1a738e5..0b9090d 100644 --- a/Documentation/media/kapi/mc-core.rst +++ b/Documentation/media/kapi/mc-core.rst @@ -262,3 +262,5 @@ in the end provide a way to use driver-specific callbacks. .. kernel-doc:: include/media/media-devnode.h .. kernel-doc:: include/media/media-entity.h + +.. kernel-doc:: 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..581e50e --- /dev/null +++ b/drivers/media/media-dev-allocator.c @@ -0,0 +1,135 @@ +/* + * media-dev-allocator.c - Media Controller Device Allocator API + * + * Copyright (c) 2016 Shuah Khan <shuahkh@osg.samsung.com> + * Copyright (c) 2016 Samsung Electronics Co., Ltd. + * + * This file is released under the GPLv2. + * Credits: Suggested by Laurent Pinchart <laurent.pinchart@ideasonboard.com> + */ + +/* + * 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 <linux/kref.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/usb.h> + +#include <media/media-device.h> + +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) + continue; + + 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; + + 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); + 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); + + 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..fad8cb9 --- /dev/null +++ b/include/media/media-dev-allocator.h @@ -0,0 +1,88 @@ +/* + * media-dev-allocator.h - Media Controller Device Allocator API + * + * Copyright (c) 2016 Shuah Khan <shuahkh@osg.samsung.com> + * Copyright (c) 2016 Samsung Electronics Co., Ltd. + * + * This file is released under the GPLv2. + * Credits: Suggested by Laurent Pinchart <laurent.pinchart@ideasonboard.com> + */ + +/* + * 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 +/** + * 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: should be filled with KBUILD_MODNAME + * + * 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 structure 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: should be filled with KBUILD_MODNAME + * + * 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