errata: workaround for Neoverse V1 errata 1791573

Neoverse V1 erratum 1791573 is a Cat B erratum present in r0p0 and
r1p0 of the V1 processor core. It is fixed in r1p1.

SDEN can be found here:
https://documentation-service.arm.com/static/60d499080320e92fa40b4625

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: Ic6f92da4d0b995bd04ca5b1673ffeedaebb71d10

docs/design/cpu-specific-build-macros.rst

@@ -323,6 +323,12 @@ For Neoverse N1, the following errata build flags are defined :
    CPU. This needs to be enabled for revisions r3p0, r3p1, r4p0, and r4p1, for
    revisions r0p0, r1p0, and r2p0 there is no workaround.
 
+For Neoverse V1, the following errata build flags are defined :
+
+-  ``ERRATA_V1_1791573``: This applies errata 1791573 workaround to Neoverse-V1
+   CPU. This needs to be enabled only for revisions r0p0 and r1p0, it is fixed
+   in r1p1.
+
 DSU Errata Workarounds
 ----------------------
 

include/lib/cpus/aarch64/neoverse_v1.h

 /*
- * Copyright (c) 2019-2020, ARM Limited. All rights reserved.
+ * Copyright (c) 2019-2021, ARM Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -20,4 +20,10 @@
 #define NEOVERSE_V1_CPUPWRCTLR_EL1				S3_0_C15_C2_7
 #define NEOVERSE_V1_CPUPWRCTLR_EL1_CORE_PWRDN_BIT		U(1)
 
+/*******************************************************************************
+ * CPU Auxiliary Control register specific definitions.
+ ******************************************************************************/
+#define NEOVERSE_V1_ACTLR2_EL1					S3_0_C15_C1_1
+#define NEOVERSE_V1_ACTLR2_EL1_BIT_2				(ULL(1) << 2)
+
 #endif /* NEOVERSE_V1_H */

lib/cpus/aarch64/neoverse_v1.S

@@ -21,6 +21,34 @@
 #error "Neoverse-V1 supports only AArch64. Compile with CTX_INCLUDE_AARCH32_REGS=0"
 #endif
 
+	/* --------------------------------------------------
+	 * Errata Workaround for Neoverse V1 Errata #1791573.
+	 * This applies to revisions r0p0 and r1p0, fixed in r1p1.
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0-x17
+	 * --------------------------------------------------
+	 */
+func errata_neoverse_v1_1791573_wa
+	/* Check workaround compatibility. */
+	mov	x17, x30
+	bl	check_errata_1791573
+	cbz	x0, 1f
+
+	/* Set bit 2 in ACTLR2_EL1 */
+	mrs     x1, NEOVERSE_V1_ACTLR2_EL1
+	orr	x1, x1, #NEOVERSE_V1_ACTLR2_EL1_BIT_2
+	msr     NEOVERSE_V1_ACTLR2_EL1, x1
+	isb
+1:
+	ret	x17
+endfunc errata_neoverse_v1_1791573_wa
+
+func check_errata_1791573
+	/* Applies to r0p0 and r1p0. */
+	mov	x1, #0x10
+	b	cpu_rev_var_ls
+endfunc check_errata_1791573
+
 	/* ---------------------------------------------
 	 * HW will do the cache maintenance while powering down
 	 * ---------------------------------------------
@@ -42,6 +70,18 @@ endfunc neoverse_v1_core_pwr_dwn
 	 */
 #if REPORT_ERRATA
 func neoverse_v1_errata_report
+	stp	x8, x30, [sp, #-16]!
+
+	bl	cpu_get_rev_var
+	mov	x8, x0
+
+	/*
+	 * Report all errata. The revision-variant information is passed to
+	 * checking functions of each errata.
+	 */
+	report_errata ERRATA_V1_1791573, neoverse_v1, 1791573
+
+	ldp	x8, x30, [sp], #16
 	ret
 endfunc neoverse_v1_errata_report
 #endif
@@ -51,8 +91,13 @@ func neoverse_v1_reset_func
 
 	/* Disable speculative loads */
 	msr	SSBS, xzr
-
 	isb
+
+#if ERRATA_V1_1791573
+	mov	x0, x18
+	bl	errata_neoverse_v1_1791573_wa
+#endif
+
 	ret	x19
 endfunc neoverse_v1_reset_func
 

lib/cpus/cpu-ops.mk

@@ -372,6 +372,10 @@ ERRATA_N1_1868343	?=0
 # exists in revisions r0p0, r1p0, and r2p0 as well but there is no workaround.
 ERRATA_N1_1946160	?=0
 
+# Flag to apply erratum 1791573 workaround during reset.  This erratum applies
+# to revisions r0p0 and r1p0 of the Neoverse V1 core, and was fixed in r1p1.
+ERRATA_V1_1791573	?=0
+
 # Flag to apply DSU erratum 798953. This erratum applies to DSUs revision r0p0.
 # Applying the workaround results in higher DSU power consumption on idle.
 ERRATA_DSU_798953	?=0
@@ -677,6 +681,10 @@ $(eval $(call add_define,ERRATA_N1_1868343))
 $(eval $(call assert_boolean,ERRATA_N1_1946160))
 $(eval $(call add_define,ERRATA_N1_1946160))
 
+# Process ERRATA_V1_1791573 flag
+$(eval $(call assert_boolean,ERRATA_V1_1791573))
+$(eval $(call add_define,ERRATA_V1_1791573))
+
 # Process ERRATA_DSU_798953 flag
 $(eval $(call assert_boolean,ERRATA_DSU_798953))
 $(eval $(call add_define,ERRATA_DSU_798953))