services/std_svc/psci/psci_entry.S

/*
 * Copyright (c) 2013-2015, 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
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <arch.h>
#include <asm_macros.S>
#include <el3_common_macros.S>
#include <psci.h>
#include <xlat_tables.h>

	.globl	psci_entrypoint
	.globl	psci_power_down_wfi

	/* --------------------------------------------------------------------
	 * This CPU has been physically powered up. It is either resuming from
	 * suspend or has simply been turned on. In both cases, call the power
	 * on finisher.
	 * --------------------------------------------------------------------
	 */
func psci_entrypoint
	/*
	 * On the warm boot path, most of the EL3 initialisations performed by
	 * 'el3_entrypoint_common' must be skipped:
	 *
	 *  - Only when the platform bypasses the BL1/BL31 entrypoint by
	 *    programming the reset address do we need to set the CPU endianness.
	 *    In other cases, we assume this has been taken care by the
	 *    entrypoint code.
	 *
	 *  - No need to determine the type of boot, we know it is a warm boot.
	 *
	 *  - Do not try to distinguish between primary and secondary CPUs, this
	 *    notion only exists for a cold boot.
	 *
	 *  - No need to initialise the memory or the C runtime environment,
	 *    it has been done once and for all on the cold boot path.
	 */
	el3_entrypoint_common					\
		_set_endian=PROGRAMMABLE_RESET_ADDRESS		\
		_warm_boot_mailbox=0				\
		_secondary_cold_boot=0				\
		_init_memory=0					\
		_init_c_runtime=0				\
		_exception_vectors=runtime_exceptions

	/* --------------------------------------------
	 * Enable the MMU with the DCache disabled. It
	 * is safe to use stacks allocated in normal
	 * memory as a result. All memory accesses are
	 * marked nGnRnE when the MMU is disabled. So
	 * all the stack writes will make it to memory.
	 * All memory accesses are marked Non-cacheable
	 * when the MMU is enabled but D$ is disabled.
	 * So used stack memory is guaranteed to be
	 * visible immediately after the MMU is enabled
	 * Enabling the DCache at the same time as the
	 * MMU can lead to speculatively fetched and
	 * possibly stale stack memory being read from
	 * other caches. This can lead to coherency
	 * issues.
	 * --------------------------------------------
	 */
	mov	x0, #DISABLE_DCACHE
	bl	bl31_plat_enable_mmu

	bl	psci_power_up_finish

	b	el3_exit
endfunc psci_entrypoint

	/* --------------------------------------------
	 * This function is called to indicate to the
	 * power controller that it is safe to power
	 * down this cpu. It should not exit the wfi
	 * and will be released from reset upon power
	 * up. 'wfi_spill' is used to catch erroneous
	 * exits from wfi.
	 * --------------------------------------------
	 */
func psci_power_down_wfi
	dsb	sy		// ensure write buffer empty
	wfi
wfi_spill:
	b	wfi_spill
endfunc psci_power_down_wfi