errata: workaround for Neoverse-V1 erratum 2108267

Neoverse-V1 erratum 2108267 is a Cat B erratum that applies to
revisions r0p0, r1p0, and r1p1 of CPU. It is still open. The
workaround is to write the value 2'b11 to the PF_MODE bits in
the CPUECTLR_EL1 register which will place the data prefetcher
in the most conservative mode instead of disabling it.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1401781/latest

Signed-off-by: nayanpatel-arm <nayankumar.patel@arm.com>
Change-Id: Iedcb84a7ad34af7083116818f49d7296f7d9bf94

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

@@ -371,6 +371,10 @@ For Neoverse V1, the following errata build flags are defined :
    CPU. This needs to be enabled for revisions r0p0, r1p0, and r1p1 of the
    CPU.  It is still open.
 
+-  ``ERRATA_V1_2108267``: This applies errata 2108267 workaround to Neoverse-V1
+   CPU. This needs to be enabled for revisions r0p0, r1p0, and r1p1 of the CPU.
+   It is still open.
+
 For Cortex-A710, the following errata build flags are defined :
 
 -  ``ERRATA_A710_1987031``: This applies errata 1987031 workaround to

include/lib/cpus/aarch64/neoverse_v1.h

@@ -15,6 +15,9 @@
 #define NEOVERSE_V1_CPUECTLR_EL1				S3_0_C15_C1_4
 #define NEOVERSE_V1_CPUECTLR_EL1_BIT_8				(ULL(1) << 8)
 #define NEOVERSE_V1_CPUECTLR_EL1_BIT_53				(ULL(1) << 53)
+#define NEOVERSE_V1_CPUECTLR_EL1_PF_MODE_CNSRV			ULL(3)
+#define CPUECTLR_EL1_PF_MODE_LSB				U(6)
+#define CPUECTLR_EL1_PF_MODE_WIDTH				U(2)
 
 /*******************************************************************************
  * CPU Power Control register specific definitions

lib/cpus/aarch64/neoverse_v1.S

@@ -259,6 +259,35 @@ func check_errata_2139242
 	b	cpu_rev_var_ls
 endfunc check_errata_2139242
 
+	/* --------------------------------------------------
+	 * Errata Workaround for Neoverse V1 Errata #2108267.
+	 * This applies to revisions r0p0, r1p0, and r1p1, it
+	 * is still open.
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0-x1, x17
+	 * --------------------------------------------------
+	 */
+func errata_neoverse_v1_2108267_wa
+	/* Check workaround compatibility. */
+	mov	x17, x30
+	bl	check_errata_2108267
+	cbz	x0, 1f
+
+	/* Apply the workaround. */
+	mrs	x1, NEOVERSE_V1_CPUECTLR_EL1
+	mov	x0, #NEOVERSE_V1_CPUECTLR_EL1_PF_MODE_CNSRV
+	bfi	x1, x0, #CPUECTLR_EL1_PF_MODE_LSB, #CPUECTLR_EL1_PF_MODE_WIDTH
+	msr	NEOVERSE_V1_CPUECTLR_EL1, x1
+1:
+	ret	x17
+endfunc errata_neoverse_v1_2108267_wa
+
+func check_errata_2108267
+	/* Applies to r0p0, r1p0, r1p1 */
+	mov	x1, #0x11
+	b	cpu_rev_var_ls
+endfunc check_errata_2108267
+
 	/* ---------------------------------------------
 	 * HW will do the cache maintenance while powering down
 	 * ---------------------------------------------
@@ -296,6 +325,7 @@ func neoverse_v1_errata_report
 	report_errata ERRATA_V1_1940577, neoverse_v1, 1940577
 	report_errata ERRATA_V1_1966096, neoverse_v1, 1966096
 	report_errata ERRATA_V1_2139242, neoverse_v1, 2139242
+	report_errata ERRATA_V1_2108267, neoverse_v1, 2108267
 
 	ldp	x8, x30, [sp], #16
 	ret
@@ -344,6 +374,11 @@ func neoverse_v1_reset_func
 	bl	errata_neoverse_v1_2139242_wa
 #endif
 
+#if ERRATA_V1_2108267
+	mov	x0, x18
+	bl	errata_neoverse_v1_2108267_wa
+#endif
+
 	ret	x19
 endfunc neoverse_v1_reset_func
 

lib/cpus/cpu-ops.mk

@@ -411,11 +411,15 @@ ERRATA_V1_1940577	?=0
 # Flag to apply erratum 1966096 workaround during reset. This erratum applies
 # to revisions r1p0 and r1p1 of the Neoverse V1 CPU and is open.  This issue
 # exists in r0p0 as well but there is no workaround for that revision.
-ERRATA_V1_1966096   ?=0
+ERRATA_V1_1966096	?=0
 
 # Flag to apply erratum 2139242 workaround during reset. This erratum applies
 # to revisions r0p0, r1p0, and r1p1 of the Neoverse V1 cpu and is still open.
-ERRATA_V1_2139242   ?=0
+ERRATA_V1_2139242	?=0
+
+# Flag to apply erratum 2108267 workaround during reset. This erratum applies
+# to revisions r0p0, r1p0, and r1p1 of the Neoverse V1 cpu and is still open.
+ERRATA_V1_2108267	?=0
 
 # Flag to apply erratum 1987031 workaround during reset. This erratum applies
 # to revisions r0p0, r1p0 and r2p0 of the Cortex-A710 cpu and is still open.
@@ -802,6 +806,10 @@ $(eval $(call add_define,ERRATA_V1_1966096))
 $(eval $(call assert_boolean,ERRATA_V1_2139242))
 $(eval $(call add_define,ERRATA_V1_2139242))
 
+# Process ERRATA_V1_2108267 flag
+$(eval $(call assert_boolean,ERRATA_V1_2108267))
+$(eval $(call add_define,ERRATA_V1_2108267))
+
 # Process ERRATA_A710_1987031 flag
 $(eval $(call assert_boolean,ERRATA_A710_1987031))
 $(eval $(call add_define,ERRATA_A710_1987031))