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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* ipa_controls.cpp - IPA control handling
*/
#include <libcamera/ipa/ipa_controls.h>
/**
* \file ipa_controls.h
* \brief Type definitions for serialized controls
*
* This file defines binary formats to store ControlList and ControlInfoMap
* instances in contiguous, self-contained memory areas called control packets.
* It describes the layout of the packets through a set of C structures. These
* formats shall be used when serializing ControlList and ControlInfoMap to
* transfer them through the IPA C interface and IPA IPC transports.
*
* A control packet contains a list of entries, each of them describing a single
* control info or control value. The packet starts with a fixed-size header
* described by the ipa_controls_header structure, followed by an array of
* fixed-size entries. Each entry is associated with data, stored either
* directly in the entry, or in a data section after the entries array.
*
* The following diagram describes the layout of the ControlList packet.
*
* ~~~~
* +-------------------------+ . .
* Header / | ipa_controls_header | | |
* | | | | |
* \ | | | |
* +-------------------------+ | |
* / | ipa_control_value_entry | | hdr.data_offset |
* | | #0 | | |
* Control | +-------------------------+ | |
* value | | ... | | |
* entries | +-------------------------+ | |
* | | ipa_control_value_entry | | hdr.size |
* \ | #hdr.entries - 1 | | |
* +-------------------------+ | |
* | empty space (optional) | | |
* +-------------------------+ <--´ . |
* / | ... | | entry[n].offset |
* Data | | ... | | |
* section | | value data for entry #n | <-----´ |
* \ | ... | |
* +-------------------------+ |
* | empty space (optional) | |
* +-------------------------+ <-------------------------´
* ~~~~
*
* The packet header contains the size of the packet, the number of entries, and
* the offset from the beginning of the packet to the data section. The packet
* entries array immediately follows the header. The data section starts at the
* offset ipa_controls_header::data_offset from the beginning of the packet, and
* shall be aligned to a multiple of 8 bytes.
*
* Entries are described by the ipa_control_value_entry structure. They contain
* the numerical ID of the control, its type, and the number of control values.
*
* The control values are stored in the data section in the platform's native
* format. The ipa_control_value_entry::offset field stores the offset from the
* beginning of the data section to the values.
*
* All control values in the data section shall be stored in the same order as
* the respective control entries, shall be aligned to a multiple of 8 bytes,
* and shall be contiguous in memory.
*
* Empty spaces may be present between the end of the entries array and the
* data section, and after the data section. They shall be ignored when parsing
* the packet.
*
* The following diagram describes the layout of the ControlInfoMap packet.
*
* ~~~~
* +-------------------------+ . .
* Header / | ipa_controls_header | | |
* | | | | |
* \ | | | |
* +-------------------------+ | |
* / | ipa_control_info_entry | | hdr.data_offset |
* | | #0 | | |
* Control | +-------------------------+ | |
* info | | ... | | |
* entries | +-------------------------+ | |
* | | ipa_control_info_entry | | hdr.size |
* \ | #hdr.entries - 1 | | |
* +-------------------------+ | |
* | empty space (optional) | | |
* +-------------------------+ <--´ . |
* / | ... | | entry[n].offset |
* Data | | ... | | |
* section | | info data for entry #n | <-----´ |
* \ | ... | |
* +-------------------------+ |
* | empty space (optional) | |
* +-------------------------+ <-------------------------´
* ~~~~
*
* The packet header is identical to the ControlList packet header.
*
* Entries are described by the ipa_control_info_entry structure. They contain
* the numerical ID and type of the control. The control info data is stored
* in the data section as described by the following diagram.
*
* ~~~~
* +-------------------------+ .
* / | ... | | entry[n].offset
* | +-------------------------+ <-----´
* Data | | minimum value (#n) | \
* section | +-------------------------+ | Entry #n
* | | maximum value (#n) | /
* | +-------------------------+
* \ | ... |
* +-------------------------+
* ~~~~
*
* The minimum and maximum value are stored in the platform's native data
* format. The ipa_control_info_entry::offset field stores the offset from the
* beginning of the data section to the info data.
*
* Info data in the data section shall be stored in the same order as the
* entries array, shall be aligned to a multiple of 8 bytes, and shall be
* contiguous in memory.
*
* As for the ControlList packet, empty spaces may be present between the end of
* the entries array and the data section, and after the data section. They
* shall be ignored when parsing the packet.
*/
/**
* \def IPA_CONTROLS_FORMAT_VERSION
* \brief The current control serialization format version
*/
/**
* \struct ipa_controls_header
* \brief Serialized control packet header
* \var ipa_controls_header::version
* Control packet format version number (shall be IPA_CONTROLS_FORMAT_VERSION)
* \var ipa_controls_header::handle
* For ControlInfoMap packets, this field contains a unique non-zero handle
* generated when the ControlInfoMap is serialized. For ControlList packets,
* this field contains the handle of the corresponding ControlInfoMap.
* \var ipa_controls_header::entries
* Number of entries in the packet
* \var ipa_controls_header::size
* The total packet size in bytes
* \var ipa_controls_header::data_offset
* Offset in bytes from the beginning of the packet of the data section start
* \var ipa_controls_header::reserved
* Reserved for future extensions
*/
static_assert(sizeof(ipa_controls_header) == 32,
"Invalid ABI size change for struct ipa_control_header");
/**
* \struct ipa_control_value_entry
* \brief Description of a serialized ControlValue entry
* \var ipa_control_value_entry::id
* The numerical ID of the control
* \var ipa_control_value_entry::type
* The type of the control (defined by enum ControlType)
* \var ipa_control_value_entry::is_array
* True if the control value stores an array, false otherwise
* \var ipa_control_value_entry::count
* The number of control array entries for array controls (1 otherwise)
* \var ipa_control_value_entry::offset
* The offset in bytes from the beginning of the data section to the control
* value data (shall be a multiple of 8 bytes).
* \var ipa_control_value_entry::padding
* Padding bytes (shall be set to 0)
*/
static_assert(sizeof(ipa_control_value_entry) == 16,
"Invalid ABI size change for struct ipa_control_value_entry");
/**
* \struct ipa_control_info_entry
* \brief Description of a serialized ControlInfo entry
* \var ipa_control_info_entry::id
* The numerical ID of the control
* \var ipa_control_info_entry::type
* The type of the control (defined by enum ControlType)
* \var ipa_control_info_entry::offset
* The offset in bytes from the beginning of the data section to the control
* info data (shall be a multiple of 8 bytes)
* \var ipa_control_info_entry::padding
* Padding bytes (shall be set to 0)
*/
static_assert(sizeof(ipa_control_info_entry) == 16,
"Invalid ABI size change for struct ipa_control_info_entry");
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