mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-28 06:34:12 +08:00
6e1d824e7a
Media Device Allocator API to allows multiple drivers share a media device. This API solves a very common use-case for media devices where one physical device (an USB stick) provides both audio and video. When such media device exposes a standard USB Audio class, a proprietary Video class, two or more independent drivers will share a single physical USB bridge. In such cases, it is necessary to coordinate access to the shared resource. 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 <shuah@kernel.org> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
64 lines
2.2 KiB
C
64 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
|
|
/*
|
|
* media-dev-allocator.h - Media Controller Device Allocator API
|
|
*
|
|
* Copyright (c) 2019 Shuah Khan <shuah@kernel.org>
|
|
*
|
|
* 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_ALLOCATOR_H
|
|
#define _MEDIA_DEV_ALLOCATOR_H
|
|
|
|
struct usb_device;
|
|
|
|
#if defined(CONFIG_MEDIA_CONTROLLER) && defined(CONFIG_USB)
|
|
/**
|
|
* media_device_usb_allocate() - Allocate and return struct &media device
|
|
*
|
|
* @udev: struct &usb_device pointer
|
|
* @module_name: should be filled with %KBUILD_MODNAME
|
|
* @owner: struct module pointer %THIS_MODULE for the driver.
|
|
* %THIS_MODULE is null for a built-in driver.
|
|
* It is safe even when %THIS_MODULE is null.
|
|
*
|
|
* 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,
|
|
const char *module_name,
|
|
struct module *owner);
|
|
/**
|
|
* media_device_delete() - Release media device. Calls kref_put().
|
|
*
|
|
* @mdev: struct &media_device pointer
|
|
* @module_name: should be filled with %KBUILD_MODNAME
|
|
* @owner: struct module pointer %THIS_MODULE for the driver.
|
|
* %THIS_MODULE is null for a built-in driver.
|
|
* It is safe even when %THIS_MODULE is null.
|
|
*
|
|
* This interface should be called to put Media Device Instance kref.
|
|
*/
|
|
void media_device_delete(struct media_device *mdev, const char *module_name,
|
|
struct module *owner);
|
|
#else
|
|
static inline struct media_device *media_device_usb_allocate(
|
|
struct usb_device *udev, const char *module_name,
|
|
struct module *owner)
|
|
{ return NULL; }
|
|
static inline void media_device_delete(
|
|
struct media_device *mdev, const char *module_name,
|
|
struct module *owner) { }
|
|
#endif /* CONFIG_MEDIA_CONTROLLER && CONFIG_USB */
|
|
#endif /* _MEDIA_DEV_ALLOCATOR_H */
|