Merge "lib: cpu: Check SCU presence in DSU before accessing DSU registers" into integration

include/lib/cpus/aarch64/neoverse_n1.h

@@ -64,4 +64,12 @@
 #define CPUPOR_EL3	S3_6_C15_C8_2
 #define CPUPMR_EL3	S3_6_C15_C8_3
 
+/******************************************************************************
+ * CPU Configuration register definitions.
+ *****************************************************************************/
+#define CPUCFR_EL1	S3_0_C15_C0_0
+
+/* SCU bit of CPU Configuration Register, EL1 */
+#define SCU_SHIFT	U(2)
+
 #endif /* NEOVERSE_N1_H */

lib/cpus/aarch64/dsu_helpers.S

 /*
- * Copyright (c) 2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -72,18 +72,36 @@ endfunc errata_dsu_798953_wa
 	 * This function is called from both assembly and C environment. So it
 	 * follows AAPCS.
 	 *
-	 * Clobbers: x0-x3
+	 * Clobbers: x0-x15
 	 * -----------------------------------------------------------------------
 	 */
 	.globl	check_errata_dsu_936184
 	.globl	errata_dsu_936184_wa
+	.weak	is_scu_present_in_dsu
+
+	/* --------------------------------------------------------------------
+	 * Default behaviour respresents SCU is always present with DSU.
+	 * CPUs can override this definition if required.
+	 *
+	 * Can clobber only: x0-x14
+	 * --------------------------------------------------------------------
+	 */
+func is_scu_present_in_dsu
+	mov	x0, #1
+	ret
+endfunc is_scu_present_in_dsu
 
 func check_errata_dsu_936184
-	mov	x2, #ERRATA_NOT_APPLIES
-	mov	x3, #ERRATA_APPLIES
+	mov	x15, x30
+	bl	is_scu_present_in_dsu
+	cmp	x0, xzr
+	/* Default error status */
+	mov	x0, #ERRATA_NOT_APPLIES
+
+	/* If SCU is not present, return without applying patch */
+	b.eq	1f
 
 	/* 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
@@ -92,13 +110,13 @@ func check_errata_dsu_936184
 	mrs	x1, CLUSTERIDR_EL1
 
 	/* DSU variant and revision bitfields in CLUSTERIDR are adjacent */
-	ubfx	x0, x1, #CLUSTERIDR_REV_SHIFT,\
+	ubfx	x2, x1, #CLUSTERIDR_REV_SHIFT,\
 			#(CLUSTERIDR_REV_BITS + CLUSTERIDR_VAR_BITS)
-	mov	x1, #(0x2 << CLUSTERIDR_VAR_SHIFT)
-	cmp	x0, x1
-	csel	x0, x2, x3, hs
+	cmp x2, #(0x2 << CLUSTERIDR_VAR_SHIFT)
+	b.hs	1f
+	mov	x0, #ERRATA_APPLIES
 1:
-	ret
+	ret	x15
 endfunc check_errata_dsu_936184
 
 	/* --------------------------------------------------

lib/cpus/aarch64/neoverse_n1.S

@@ -22,6 +22,19 @@
 #endif
 
 	.global neoverse_n1_errata_ic_trap_handler
+	.global is_scu_present_in_dsu
+
+/*
+ * Check DSU is configured with SCU and L3 unit
+ * 1-> SCU present
+ * 0-> SCU not present
+ */
+func is_scu_present_in_dsu
+	mrs	x0, CPUCFR_EL1
+	ubfx	x0, x0, #SCU_SHIFT, #1
+	eor	x0, x0, #1
+	ret
+endfunc is_scu_present_in_dsu
 
 /* --------------------------------------------------
  * Errata Workaround for Neoverse N1 Erratum 1043202.