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/*
* Media device discovery library
*
* Copyright (C) 2012 Ideas on board SPRL
*
* Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __MEDIA_ENUMERATE_H__
#define __MEDIA_ENUMERATE_H__
struct media_enumerate;
/**
* @brief Create a new media device enumeration context.
*
* Media device enumeration contexts are used to enumerate media devices. They
* store all context information required by enumeration and cache the
* enumeration results for later access. Enumeration itself is performed by the
* separate media_enumerate_scan() function.
*
* Enumeration contexts are reference-counted, see media_enumerate_ref() and
* media_enumerate_unref() for more information.
*
* @return A pointer to the new media device enumeration context or NULL if
* memory cannot be allocated.
*/
struct media_enumerate *media_enumerate_new(void);
/**
* @brief Take a reference to the enumeration context.
* @param media_enum - enumeration context instance.
*
* Media device enumeration contexts are reference-counted. Taking a reference
* to an enumeration context prevents it and all the information it stores from
* being freed until all references are released. The reference count is
* initialized to 1 when the context is created.
*
* @return A pointer to @a media.
*/
struct media_enumerate *media_enumerate_ref(struct media_enumerate *media_enum);
/**
* @brief Release a reference to the enumeration context.
* @param media_enum - enumeration context instance.
*
* Release a reference to the enumeration context. When the reference count
* reaches 0 this function frees the context, including all information it
* stores.
*/
void media_enumerate_unref(struct media_enumerate *media_enum);
/**
* @brief Enumerate media devices in the system
* @param media_enum - enumeration context instance.
*
* Scan the system to locate all available media devices. This function must be
* called once and only once before accessing the list of enumerated devices.
*
* Devices are enumerated using libudev if available or through sysfs otherwise.
* sysfs-based enumeration requires device nodes to use the standard Linux
* device names and be numbered by the device sysfs device number. For instance
* the device node corresponding to /sys/class/video4linux/video0 must be named
* /dev/video0. libudev-based enumeration doesn't have this restriction.
*
* Media devices are enumerated by scanning media controller, V4L and ALSA
* kernel devices, in that order. Emulated media devices are created as needed
* for V4L devices that are not part of a media controller based device. ALSA
* devices without a corresponding media controller or V4L devices are skipped.
*
* @return Zero on success or a negative error code on failure.
*/
int media_enumerate_scan(struct media_enumerate *media_enum);
/**
* @brief Get the number of media devices found during enumeration
* @param media_enum - enumeration context instance.
*
* This function returns the total number of media devices found in the system
* during enumeration. If media devices haven't been enumerated yet it will
* return 0.
*
* @return The number of media devices found in the system
*/
unsigned int media_enumerate_get_devices_count(struct media_enumerate *media_enum);
/**
* @brief Get the media devices
* @param media_enum - enumeration context instance.
*
* This function returns a pointer to the array of enumerated media devices. If
* If media devices haven't been enumerated yet it will return NULL.
*
* The array of media devices is owned by the enumeration context and will be
* freed when the enumeration context is destroyed.
*
* @return A pointer to an array of media devices
*/
struct media_device **media_enumerate_get_devices(struct media_enumerate *media_enum);
#endif /* __MEDIA_ENUMERATE_H__ */
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