lib/cpus/aarch64/dsu_helpers.S

/*
 * Copyright (c) 2019, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <asm_macros.S>
#include <dsu_def.h>
#include <lib/cpus/errata_report.h>

	/* -----------------------------------------------------------------------
	 * DSU erratum 936184 check function
	 * Checks the DSU variant, revision and configuration to determine if
	 * the erratum applies. Erratum applies if ACP interface is present
	 * in the DSU and revision-variant < r2p0.
	 *
	 * The erratum was fixed in r2p0.
	 *
	 * This function is called from both assembly and C environment. So it
	 * follows AAPCS.
	 *
	 * Clobbers: x0-x3
	 * -----------------------------------------------------------------------
	 */
	.globl	check_errata_dsu_936184
	.globl	errata_dsu_936184_wa

func check_errata_dsu_936184
	mov	x2, #ERRATA_NOT_APPLIES
	mov	x3, #ERRATA_APPLIES

	/* Erratum applies only if DSU has the ACP interface */
	mov	x0, x2
	mrs	x1, CLUSTERCFR_EL1
	ubfx	x1, x1, #CLUSTERCFR_ACP_SHIFT, #1
	cbz	x1, 1f

	/* If ACP is present, check if DSU is older than r2p0 */
	mrs	x1, CLUSTERIDR_EL1

	/* DSU variant and revision bitfields in CLUSTERIDR are adjacent */
	ubfx	x0, x1, #CLUSTERIDR_REV_SHIFT,\
			#(CLUSTERIDR_REV_BITS + CLUSTERIDR_VAR_BITS)
	mov	x1, #(0x2 << CLUSTERIDR_VAR_SHIFT)
	cmp	x0, x1
	csel	x0, x2, x3, hs
1:
	ret
endfunc check_errata_dsu_936184

	/* --------------------------------------------------
	 * Errata Workaround for DSU erratum #936184.
	 *
	 * Can clobber only: x0-x17
	 * --------------------------------------------------
	 */
func errata_dsu_936184_wa
	mov	x17, x30
	bl	check_errata_dsu_936184
	cbz	x0, 1f

	/* If erratum applies, we set a mask to a DSU control register */
	mrs	x0, CLUSTERACTLR_EL1
	ldr	x1, =DSU_ERRATA_936184_MASK
	orr	x0, x0, x1
	msr	CLUSTERACTLR_EL1, x0
	isb
1:
	ret	x17
endfunc errata_dsu_936184_wa