xref: /xnu-12377.41.6/iokit/Kernel/IOStateReporter.cpp (revision bbb1b6f9e71b8cdde6e5cd6f4841f207dee3d828)

/*
 * Copyright (c) 2012-2013 Apple Computer, Inc.  All Rights Reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#define IOKIT_ENABLE_SHARED_PTR

#include <libkern/c++/OSSharedPtr.h>
#include <IOKit/IOKernelReportStructs.h>
#include <IOKit/IOKernelReporters.h>
#include "IOReporterDefs.h"


#define super IOReporter
OSDefineMetaClassAndStructors(IOStateReporter, IOReporter);


/* static */
OSSharedPtr<IOStateReporter>
IOStateReporter::with(IOService *reportingService,
    IOReportCategories categories,
    int nstates,
    IOReportUnit unit /* = kIOReportUnitHWTicks*/)
{
	OSSharedPtr<IOStateReporter> reporter;

	if (nstates > INT16_MAX) {
		return nullptr;
	}

	reporter = OSMakeShared<IOStateReporter>();
	if (!reporter) {
		return nullptr;
	}

	if (!reporter->initWith(reportingService, categories, (int16_t) nstates, unit)) {
		return nullptr;
	}

	return reporter;
}

bool
IOStateReporter::initWith(IOService *reportingService,
    IOReportCategories categories,
    int16_t nstates,
    IOReportUnit unit)
{
	bool success = false;

	IOReportChannelType channelType = {
		.categories = categories,
		.report_format = kIOReportFormatState,
		.nelements = static_cast<uint16_t>(nstates),
		.element_idx = 0
	};

	if (super::init(reportingService, channelType, unit) != true) {
		IORLOG("ERROR super::initWith failed");
		success = false;
		goto finish;
	}

	_currentStates = NULL;
	_lastUpdateTimes = NULL;

	success = true;

finish:
	return success;
}


void
IOStateReporter::free(void)
{
	if (_currentStates) {
		PREFL_MEMOP_PANIC(_nChannels, int);
		IOFreeData(_currentStates, (size_t)_nChannels * sizeof(int));
	}
	if (_lastUpdateTimes) {
		PREFL_MEMOP_PANIC(_nChannels, uint64_t);
		IOFreeData(_lastUpdateTimes, (size_t)_nChannels * sizeof(uint64_t));
	}

	super::free();
}


IOReturn
IOStateReporter::handleSwapPrepare(int newNChannels)
{
	IOReturn res = kIOReturnError;
	size_t newCurStatesSize, newTSSize;

	//IORLOG("handleSwapPrepare (state) _nChannels before = %u", _nChannels);

	IOREPORTER_CHECK_CONFIG_LOCK();

	if (_swapCurrentStates || _swapLastUpdateTimes) {
		panic("IOStateReporter::_swap* already in use");
	}

	// new currentStates buffer
	PREFL_MEMOP_FAIL(newNChannels, int);
	newCurStatesSize = (size_t)newNChannels * sizeof(int);
	_swapCurrentStates = (int*)IOMallocData(newCurStatesSize);
	if (_swapCurrentStates == NULL) {
		res = kIOReturnNoMemory; goto finish;
	}
	memset(_swapCurrentStates, -1, newCurStatesSize); // init w/"no state"

	// new timestamps buffer
	PREFL_MEMOP_FAIL(newNChannels, uint64_t);
	newTSSize = (size_t)newNChannels * sizeof(uint64_t);
	_swapLastUpdateTimes = (uint64_t *)IOMallocZeroData(newTSSize);
	if (_swapLastUpdateTimes == NULL) {
		res = kIOReturnNoMemory; goto finish;
	}

	res = super::handleSwapPrepare(newNChannels);

finish:
	if (res) {
		if (_swapCurrentStates) {
			IOFreeData(_swapCurrentStates, newCurStatesSize);
			_swapCurrentStates = NULL;
		}
		if (_swapLastUpdateTimes) {
			IOFreeData(_swapLastUpdateTimes, newTSSize);
			_swapLastUpdateTimes = NULL;
		}
	}

	return res;
}

IOReturn
IOStateReporter::handleAddChannelSwap(uint64_t channelID,
    const OSSymbol *symChannelName)
{
	IOReturn res = kIOReturnError;
	int cnt;
	int *tmpCurStates;
	uint64_t *tmpTimestamps;
	bool swapComplete = false;

	//IORLOG("IOStateReporter::handleSwap");

	if (!_swapCurrentStates || !_swapLastUpdateTimes) {
		IORLOG("IOReporter::handleSwap ERROR swap variables uninitialized!");
		goto finish;
	}

	IOREPORTER_CHECK_CONFIG_LOCK();
	IOREPORTER_CHECK_LOCK();

	// Copy any existing buffers
	if (_currentStates) {
		PREFL_MEMOP_FAIL(_nChannels, int);
		memcpy(_swapCurrentStates, _currentStates,
		    (size_t)_nChannels * sizeof(int));

		if (!_lastUpdateTimes) {
			panic("IOStateReporter::handleAddChannelSwap _lastUpdateTimes unset despite non-NULL _currentStates");
		}
		PREFL_MEMOP_FAIL(_nChannels, uint64_t);
		memcpy(_swapLastUpdateTimes, _lastUpdateTimes,
		    (size_t)_nChannels * sizeof(uint64_t));
	}

	// Update principal instance variables, keep old values in _swap* for cleanup
	tmpCurStates = _currentStates;
	_currentStates = _swapCurrentStates;
	_swapCurrentStates = tmpCurStates;

	tmpTimestamps = _lastUpdateTimes;
	_lastUpdateTimes = _swapLastUpdateTimes;
	_swapLastUpdateTimes = tmpTimestamps;

	swapComplete = true;

	// subclass success

	// invoke superclass(es): base class updates _nChannels & _nElements
	res = super::handleAddChannelSwap(channelID, symChannelName);
	if (res) {
		IORLOG("handleSwap(state) ERROR super::handleSwap failed!");
		goto finish;
	}

	// Channel added successfully, initialize the new channel's state_ids to 0..nStates-1
	for (cnt = 0; cnt < _channelDimension; cnt++) {
		handleSetStateID(channelID, cnt, (uint64_t)cnt);
	}

finish:
	if (res && swapComplete) {
		// unswap so the unused buffers get cleaned up
		tmpCurStates = _currentStates;
		_currentStates = _swapCurrentStates;
		_swapCurrentStates = tmpCurStates;

		tmpTimestamps = _lastUpdateTimes;
		_lastUpdateTimes = _swapLastUpdateTimes;
		_swapLastUpdateTimes = tmpTimestamps;
	}

	return res;
}


void
IOStateReporter::handleSwapCleanup(int swapNChannels)
{
	IOREPORTER_CHECK_CONFIG_LOCK();

	super::handleSwapCleanup(swapNChannels);

	if (_swapCurrentStates) {
		PREFL_MEMOP_PANIC(swapNChannels, int);
		IOFreeData(_swapCurrentStates, (size_t)swapNChannels * sizeof(int));
		_swapCurrentStates = NULL;
	}
	if (_swapLastUpdateTimes) {
		PREFL_MEMOP_PANIC(swapNChannels, uint64_t);
		IOFreeData(_swapLastUpdateTimes, (size_t)swapNChannels * sizeof(uint64_t));
		_swapLastUpdateTimes = NULL;
	}
}


IOReturn
IOStateReporter::_getStateIndices(uint64_t channel_id,
    uint64_t state_id,
    int *channel_index,
    int *state_index)
{
	IOReturn res = kIOReturnError;
	int cnt;
	IOStateReportValues *values;
	int element_index = 0;

	IOREPORTER_CHECK_LOCK();

	if (getChannelIndices(channel_id,
	    channel_index,
	    &element_index) != kIOReturnSuccess) {
		res = kIOReturnBadArgument;

		goto finish;
	}

	for (cnt = 0; cnt < _channelDimension; cnt++) {
		values = (IOStateReportValues *)getElementValues(element_index + cnt);

		if (values == NULL) {
			res = kIOReturnError;
			goto finish;
		}

		if (values->state_id == state_id) {
			*state_index = cnt;
			res = kIOReturnSuccess;
			goto finish;
		}
	}

	res = kIOReturnBadArgument;

finish:
	return res;
}


IOReturn
IOStateReporter::setChannelState(uint64_t channel_id,
    uint64_t new_state_id)
{
	IOReturn res = kIOReturnError;
	int channel_index, new_state_index;
	uint64_t last_intransition = 0;
	uint64_t prev_state_residency = 0;

	lockReporter();

	if (_getStateIndices(channel_id, new_state_id, &channel_index, &new_state_index) == kIOReturnSuccess) {
		res = handleSetStateByIndices(channel_index, new_state_index,
		    last_intransition,
		    prev_state_residency);
		goto finish;
	}

	res = kIOReturnBadArgument;

finish:
	unlockReporter();
	return res;
}

IOReturn
IOStateReporter::setChannelState(uint64_t channel_id,
    uint64_t new_state_id,
    uint64_t last_intransition,
    uint64_t prev_state_residency)
{
	return setChannelState(channel_id, new_state_id);
}

IOReturn
IOStateReporter::overrideChannelState(uint64_t channel_id,
    uint64_t state_id,
    uint64_t time_in_state,
    uint64_t intransitions,
    uint64_t last_intransition /*=0*/)
{
	IOReturn res = kIOReturnError;
	int channel_index, state_index;

	lockReporter();

	if (_getStateIndices(channel_id, state_id, &channel_index, &state_index) == kIOReturnSuccess) {
		if (_lastUpdateTimes[channel_index]) {
			panic("overrideChannelState() cannot be used after setChannelState()!");
		}

		res = handleOverrideChannelStateByIndices(channel_index, state_index,
		    time_in_state, intransitions,
		    last_intransition);
		goto finish;
	}

	res = kIOReturnBadArgument;

finish:
	unlockReporter();
	return res;
}


IOReturn
IOStateReporter::handleOverrideChannelStateByIndices(int channel_index,
    int state_index,
    uint64_t time_in_state,
    uint64_t intransitions,
    uint64_t last_intransition /*=0*/)
{
	IOReturn kerr, result = kIOReturnError;
	IOStateReportValues state_values;
	int element_index;

	if (channel_index < 0 || channel_index >= _nChannels) {
		result = kIOReturnBadArgument; goto finish;
	}

	if (channel_index < 0 || channel_index > (_nElements - state_index)
	    / _channelDimension) {
		result = kIOReturnOverrun; goto finish;
	}
	element_index = channel_index * _channelDimension + state_index;

	kerr = copyElementValues(element_index, (IOReportElementValues*)&state_values);
	if (kerr) {
		result = kerr; goto finish;
	}

	// last_intransition = 0 -> no current state ("residency summary only")
	state_values.last_intransition = last_intransition;
	state_values.intransitions = intransitions;
	state_values.upticks = time_in_state;

	// determines current time for metadata
	kerr = setElementValues(element_index, (IOReportElementValues *)&state_values);
	if (kerr) {
		result = kerr; goto finish;
	}

	// success
	result = kIOReturnSuccess;

finish:
	return result;
}


IOReturn
IOStateReporter::incrementChannelState(uint64_t channel_id,
    uint64_t state_id,
    uint64_t time_in_state,
    uint64_t intransitions,
    uint64_t last_intransition /*=0*/)
{
	IOReturn res = kIOReturnError;
	int channel_index, state_index;

	lockReporter();

	if (_getStateIndices(channel_id, state_id, &channel_index, &state_index) == kIOReturnSuccess) {
		if (_lastUpdateTimes[channel_index]) {
			panic("incrementChannelState() cannot be used after setChannelState()!");
		}

		res = handleIncrementChannelStateByIndices(channel_index, state_index,
		    time_in_state, intransitions,
		    last_intransition);
		goto finish;
	}

	res = kIOReturnBadArgument;

finish:
	unlockReporter();
	return res;
}


IOReturn
IOStateReporter::handleIncrementChannelStateByIndices(int channel_index,
    int state_index,
    uint64_t time_in_state,
    uint64_t intransitions,
    uint64_t last_intransition /*=0*/)
{
	IOReturn kerr, result = kIOReturnError;
	IOStateReportValues state_values;
	int element_index;

	if (channel_index < 0 || channel_index >= _nChannels) {
		result = kIOReturnBadArgument; goto finish;
	}

	if (channel_index < 0 || channel_index > (_nElements - state_index)
	    / _channelDimension) {
		result = kIOReturnOverrun; goto finish;
	}
	element_index = channel_index * _channelDimension + state_index;

	kerr = copyElementValues(element_index, (IOReportElementValues*)&state_values);
	if (kerr) {
		result = kerr;
		goto finish;
	}

	state_values.last_intransition = last_intransition;
	state_values.intransitions += intransitions;
	state_values.upticks += time_in_state;

	// determines current time for metadata
	kerr = setElementValues(element_index, (IOReportElementValues *)&state_values);
	if (kerr) {
		result = kerr;
		goto finish;
	}

	// success
	result = kIOReturnSuccess;

finish:
	return result;
}


IOReturn
IOStateReporter::setState(uint64_t new_state_id)
{
	uint64_t last_intransition = 0;
	uint64_t prev_state_residency = 0;
	IOReturn res = kIOReturnError;
	IOStateReportValues *values;
	int channel_index = 0, element_index = 0, new_state_index = 0;
	int cnt;

	lockReporter();

	if (_nChannels == 1) {
		for (cnt = 0; cnt < _channelDimension; cnt++) {
			new_state_index = element_index + cnt;

			values = (IOStateReportValues *)getElementValues(new_state_index);

			if (values == NULL) {
				res = kIOReturnError;
				goto finish;
			}

			if (values->state_id == new_state_id) {
				res = handleSetStateByIndices(channel_index, new_state_index,
				    last_intransition,
				    prev_state_residency);
				goto finish;
			}
		}
	}

	res = kIOReturnBadArgument;

finish:
	unlockReporter();
	return res;
}

IOReturn
IOStateReporter::setState(uint64_t new_state_id,
    uint64_t last_intransition,
    uint64_t prev_state_residency)
{
	return setState(new_state_id);
}

IOReturn
IOStateReporter::setStateID(uint64_t channel_id,
    int state_index,
    uint64_t state_id)
{
	IOReturn res = kIOReturnError;

	lockReporter();

	res = handleSetStateID(channel_id, state_index, state_id);

	unlockReporter();

	return res;
}


IOReturn
IOStateReporter::handleSetStateID(uint64_t channel_id,
    int state_index,
    uint64_t state_id)
{
	IOReturn res = kIOReturnError;
	IOStateReportValues state_values;
	int element_index = 0;

	IOREPORTER_CHECK_LOCK();

	if (getFirstElementIndex(channel_id, &element_index) == kIOReturnSuccess) {
		if (state_index >= _channelDimension) {
			res = kIOReturnBadArgument; goto finish;
		}
		if (_nElements - state_index <= element_index) {
			res = kIOReturnOverrun; goto finish;
		}
		element_index += state_index;

		if (copyElementValues(element_index, (IOReportElementValues *)&state_values) != kIOReturnSuccess) {
			res = kIOReturnBadArgument;
			goto finish;
		}

		state_values.state_id = state_id;

		res = setElementValues(element_index, (IOReportElementValues *)&state_values);
	}

	// FIXME: set a bit somewhere (reporter-wide?) that state_ids can no longer be
	// assumed to be contiguous
finish:
	return res;
}

IOReturn
IOStateReporter::setStateByIndices(int channel_index,
    int new_state_index)
{
	IOReturn res = kIOReturnError;
	uint64_t last_intransition = 0;
	uint64_t prev_state_residency = 0;

	lockReporter();

	res = handleSetStateByIndices(channel_index, new_state_index,
	    last_intransition, prev_state_residency);

	unlockReporter();

	return res;
}

IOReturn
IOStateReporter::setStateByIndices(int channel_index,
    int new_state_index,
    uint64_t last_intransition,
    uint64_t prev_state_residency)
{
	return setStateByIndices(channel_index, new_state_index);
}

IOReturn
IOStateReporter::handleSetStateByIndices(int channel_index,
    int new_state_index,
    uint64_t last_intransition,
    uint64_t prev_state_residency)
{
	IOReturn res = kIOReturnError;

	IOStateReportValues curr_state_values, new_state_values;
	int curr_state_index = 0;
	int curr_element_index, new_element_index;
	uint64_t last_ch_update_time = 0;
	uint64_t recordTime = mach_absolute_time();

	IOREPORTER_CHECK_LOCK();

	if (channel_index < 0 || channel_index >= _nChannels) {
		res = kIOReturnBadArgument; goto finish;
	}

	// if no timestamp provided, last_intransition = time of recording (now)
	if (last_intransition == 0) {
		last_intransition = recordTime;
	}

	// First update target state if different than the current state
	// _currentStates[] initialized to -1 to detect first state transition
	curr_state_index = _currentStates[channel_index];
	if (new_state_index != curr_state_index) {
		// fetch element data
		if (channel_index < 0 || channel_index > (_nElements - new_state_index)
		    / _channelDimension) {
			res = kIOReturnOverrun; goto finish;
		}
		new_element_index = channel_index * _channelDimension + new_state_index;
		if (copyElementValues(new_element_index,
		    (IOReportElementValues *)&new_state_values)) {
			res = kIOReturnBadArgument;
			goto finish;
		}

		// Update new state's transition info
		new_state_values.intransitions += 1;
		new_state_values.last_intransition = last_intransition;

		// and store the values
		res = setElementValues(new_element_index,
		    (IOReportElementValues *)&new_state_values,
		    recordTime);

		if (res != kIOReturnSuccess) {
			goto finish;
		}

		_currentStates[channel_index] = new_state_index;
	}

	/* Now update time spent in any previous state
	 *  If new_state_index = curr_state_index, this updates time in the
	 *  current state.  If this is the channel's first state transition,
	 *  the last update time will be zero.
	 *
	 *  Note: While setState() should never be called on a channel being
	 *  updated with increment/overrideChannelState(), that's another way
	 *  that the last update time might not exist.  Regardless, if there
	 *  is no basis for determining time spent in previous state, there's
	 *  nothing to update!
	 */
	last_ch_update_time = _lastUpdateTimes[channel_index];
	if (last_ch_update_time != 0) {
		if (channel_index < 0 || channel_index > (_nElements - curr_state_index)
		    / _channelDimension) {
			res = kIOReturnOverrun; goto finish;
		}
		curr_element_index = channel_index * _channelDimension + curr_state_index;
		if (copyElementValues(curr_element_index,
		    (IOReportElementValues *)&curr_state_values)) {
			res = kIOReturnBadArgument;
			goto finish;
		}
		// compute the time spent in previous state, unless provided
		if (prev_state_residency == 0) {
			prev_state_residency = last_intransition - last_ch_update_time;
		}

		curr_state_values.upticks += prev_state_residency;

		res = setElementValues(curr_element_index,
		    (IOReportElementValues*)&curr_state_values,
		    recordTime);

		if (res != kIOReturnSuccess) {
			goto finish;
		}
	}

	// record basis for next "time in prior state" calculation
	// (also arms a panic in override/incrementChannelState())
	_lastUpdateTimes[channel_index] = last_intransition;

finish:
	return res;
}


// blocks might make this slightly easier?
uint64_t
IOStateReporter::getStateInTransitions(uint64_t channel_id,
    uint64_t state_id)
{
	return _getStateValue(channel_id, state_id, kInTransitions);
}

uint64_t
IOStateReporter::getStateResidencyTime(uint64_t channel_id,
    uint64_t state_id)
{
	return _getStateValue(channel_id, state_id, kResidencyTime);
}

uint64_t
IOStateReporter::getStateLastTransitionTime(uint64_t channel_id,
    uint64_t state_id)
{
	return _getStateValue(channel_id, state_id, kLastTransitionTime);
}

uint64_t
IOStateReporter::_getStateValue(uint64_t channel_id,
    uint64_t state_id,
    enum valueSelector value)
{
	int channel_index = 0, element_index = 0, cnt;
	IOStateReportValues *values = NULL;
	uint64_t result = kIOReportInvalidValue;

	lockReporter();

	if (getChannelIndices(channel_id, &channel_index, &element_index) == kIOReturnSuccess) {
		if (updateChannelValues(channel_index) == kIOReturnSuccess) {
			for (cnt = 0; cnt < _channelDimension; cnt++) {
				values = (IOStateReportValues *)getElementValues(element_index);

				if (state_id == values->state_id) {
					switch (value) {
					case kInTransitions:
						result = values->intransitions;
						break;
					case kResidencyTime:
						result = values->upticks;
						break;
					case kLastTransitionTime:
						result = values->last_intransition;
						break;
					default:
						break;
					}

					break;
				}

				element_index++;
			}
		}
	}

	unlockReporter();
	return result;
}


uint64_t
IOStateReporter::getStateLastChannelUpdateTime(uint64_t channel_id)
{
	int channel_index;
	uint64_t result = kIOReportInvalidValue;

	lockReporter();

	if (getChannelIndex(channel_id, &channel_index) == kIOReturnSuccess) {
		result = _lastUpdateTimes[channel_index];
	}

	unlockReporter();

	return result;
}


/* updateChannelValues() is called to refresh state before being
 *  reported outside the reporter.  In the case of IOStateReporter,
 *  this is primarily an update to the "time in state" data.
 */
IOReturn
IOStateReporter::updateChannelValues(int channel_index)
{
	IOReturn kerr, result = kIOReturnError;

	int state_index, element_idx;
	uint64_t currentTime;
	uint64_t last_ch_update_time;
	uint64_t time_in_state;
	IOStateReportValues state_values;

	IOREPORTER_CHECK_LOCK();

	if (channel_index < 0 || channel_index >= _nChannels) {
		result = kIOReturnBadArgument; goto finish;
	}

	/* First check to see whether this channel has begun self-
	 *  calculation of time in state.  It's possible this channel
	 *  has yet to be initialized or that the driver is updating
	 *  the channel with override/incrementChannelState() which
	 *  never enable automatic time-in-state updates.  In that case,
	 *  there is nothing to update and we return success.
	 */
	last_ch_update_time = _lastUpdateTimes[channel_index];
	if (last_ch_update_time == 0) {
		result = kIOReturnSuccess; goto finish;
	}

	// figure out the current state (if any)
	state_index = _currentStates[channel_index];

	// e.g. given 4 4-state channels, the boundary is ch[3].st[3] <- _elems[15]
	if (channel_index < 0 || channel_index > (_nElements - state_index)
	    / _channelDimension) {
		result = kIOReturnOverrun; goto finish;
	}
	element_idx = channel_index * _channelDimension + state_index;

	// get the current values
	kerr = copyElementValues(element_idx, (IOReportElementValues*)&state_values);
	if (kerr) {
		result = kerr; goto finish;
	}

	// calculate time in state
	currentTime = mach_absolute_time();
	time_in_state = currentTime - last_ch_update_time;
	state_values.upticks += time_in_state;

	// and store the values
	kerr = setElementValues(element_idx,
	    (IOReportElementValues *)&state_values,
	    currentTime);
	if (kerr) {
		result = kerr; goto finish;
	}

	// Record basis for next "prior time" calculation
	_lastUpdateTimes[channel_index] = currentTime;


	// success
	result = kIOReturnSuccess;

finish:
	return result;
}

/* static */ OSPtr<IOReportLegendEntry>
IOStateReporter::createLegend(const uint64_t *channelIDs,
    const char **channelNames,
    int channelCount,
    int nstates,
    IOReportCategories categories,
    IOReportUnit unit)
{
	IOReportChannelType channelType = {
		.categories = categories,
		.report_format = kIOReportFormatState,
		.nelements = static_cast<uint16_t>(nstates),
		.element_idx = 0
	};

	return IOReporter::legendWith(channelIDs, channelNames, channelCount, channelType, unit);
}