plat/common/aarch64/plat_psci_common.c

/*
 * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of ARM nor the names of its contributors may be used
 * to endorse or promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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 */

#include <arch.h>
#include <assert.h>
#include <platform.h>
#include <psci.h>

/*
 * The PSCI generic code uses this API to let the platform participate in state
 * coordination during a power management operation. It compares the platform
 * specific local power states requested by each cpu for a given power domain
 * and returns the coordinated target power state that the domain should
 * enter. A platform assigns a number to a local power state. This default
 * implementation assumes that the platform assigns these numbers in order of
 * increasing depth of the power state i.e. for two power states X & Y, if X < Y
 * then X represents a shallower power state than Y. As a result, the
 * coordinated target local power state for a power domain will be the minimum
 * of the requested local power states.
 */
plat_local_state_t plat_get_target_pwr_state(unsigned int lvl,
					     const plat_local_state_t *states,
					     unsigned int ncpu)
{
	plat_local_state_t target = PLAT_MAX_OFF_STATE, temp;

	assert(ncpu);

	do {
		temp = *states++;
		if (temp < target)
			target = temp;
	} while (--ncpu);

	return target;
}