fix(errata): workaround for Rainier erratum 1868343

Rainier CPU is based on Neoverse N1 R4P0 version which exhibits
the erratum 1868343. This patch inherits the workaround from
neoverse_n1.S file into rainier.S file for erratum 1868343.

Signed-off-by: Manoj Kumar <manoj.kumar3@arm.com>
Change-Id: I735595229716a77d26369943086de08384cafa70

lib/cpus/aarch64/rainier.S

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Arm Limited. All rights reserved.
+ * Copyright (c) 2020-2022, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -41,6 +41,40 @@ func rainier_disable_speculative_loads
 	ret
 endfunc rainier_disable_speculative_loads
 
+	/* --------------------------------------------------
+	 * Errata Workaround for Neoverse N1 Errata #1868343.
+	 * This applies to revision <= r4p0 of Neoverse N1.
+	 * This workaround is the same as the workaround for
+	 * errata 1262606 and 1275112 but applies to a wider
+	 * revision range.
+	 * Rainier R0P0 is based on Neoverse N1 R4P0 so the
+	 * workaround checks for r0p0 version of Rainier CPU.
+	 * Inputs:
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0, x1 & x17
+	 * --------------------------------------------------
+	 */
+func errata_n1_1868343_wa
+	/*
+	 * Compare x0 against revision r4p0
+	 */
+	mov	x17, x30
+	bl	check_errata_1868343
+	cbz	x0, 1f
+	mrs	x1, RAINIER_CPUACTLR_EL1
+	orr	x1, x1, RAINIER_CPUACTLR_EL1_BIT_13
+	msr	RAINIER_CPUACTLR_EL1, x1
+	isb
+1:
+	ret	x17
+endfunc errata_n1_1868343_wa
+
+func check_errata_1868343
+	/* Applies to r0p0 of Rainier CPU */
+	mov	x1, #0x00
+	b	cpu_rev_var_ls
+endfunc check_errata_1868343
+
 func rainier_reset_func
 	mov	x19, x30
 
@@ -55,6 +89,11 @@ func rainier_reset_func
 	bl	cpu_get_rev_var
 	mov	x18, x0
 
+#if ERRATA_N1_1868343
+	mov	x0, x18
+	bl	errata_n1_1868343_wa
+#endif
+
 #if ENABLE_AMU
 	/* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */
 	mrs	x0, actlr_el3
@@ -101,6 +140,12 @@ func rainier_errata_report
 	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_N1_1868343, rainier, 1868343
+
 	ldp	x8, x30, [sp], #16
 	ret
 endfunc rainier_errata_report