Neovers N1: added support to update presence of External LLC

CPUECTLR_EL1.EXTLLC bit indicates the presense of internal or external
last level cache(LLC) in the system, the reset value is internal LLC.

To cater for the platforms(like N1SDP) which has external LLC present
introduce a new build option 'NEOVERSE_N1_EXTERNAL_LLC' which can be
enabled by platform port.
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Ibf475fcd6fd44401897a71600f4eafe989921363

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

@@ -324,6 +324,11 @@ architecture that can be enabled by the platform as desired.
    as recommended in section "4.7 Non-Temporal Loads/Stores" of the
    `Cortex-A57 Software Optimization Guide`_.
 
+-  ``NEOVERSE_N1_EXTERNAL_LLC``: This flag indicates that an external last
+   level cache(LLC) is present in the system, and that the DataSource field
+   on the master CHI interface indicates when data is returned from the LLC.
+   This is used to control how the LL_CACHE* PMU events count.
+
 --------------
 
 *Copyright (c) 2014-2019, Arm Limited and Contributors. All rights reserved.*

include/lib/cpus/aarch64/neoverse_n1.h

 /*
- * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -35,6 +35,7 @@
 
 #define NEOVERSE_N1_WS_THR_L2_MASK	(ULL(3) << 24)
 #define NEOVERSE_N1_CPUECTLR_EL1_MM_TLBPF_DIS_BIT	(ULL(1) << 51)
+#define NEOVERSE_N1_CPUECTLR_EL1_EXTLLC_BIT		(ULL(1) << 0)
 
 /*******************************************************************************
  * CPU Auxiliary Control register specific definitions.

lib/cpus/aarch64/neoverse_n1.S

@@ -465,6 +465,13 @@ func neoverse_n1_reset_func
 	msr	CPUAMCNTENSET_EL0, x0
 #endif
 
+#if NEOVERSE_N1_EXTERNAL_LLC
+	/* Some system may have External LLC, core needs to be made aware */
+	mrs     x0, NEOVERSE_N1_CPUECTLR_EL1
+	orr     x0, x0, NEOVERSE_N1_CPUECTLR_EL1_EXTLLC_BIT
+	msr     NEOVERSE_N1_CPUECTLR_EL1, x0
+#endif
+
 #if ERRATA_DSU_936184
 	bl	errata_dsu_936184_wa
 #endif

lib/cpus/cpu-ops.mk

 #
-# Copyright (c) 2014-2019, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -20,6 +20,10 @@ WORKAROUND_CVE_2017_5715	?=1
 WORKAROUND_CVE_2018_3639	?=1
 DYNAMIC_WORKAROUND_CVE_2018_3639	?=0
 
+# Flag to indicate internal or external Last level cache
+# By default internal
+NEOVERSE_N1_EXTERNAL_LLC	?=0
+
 # Process SKIP_A57_L1_FLUSH_PWR_DWN flag
 $(eval $(call assert_boolean,SKIP_A57_L1_FLUSH_PWR_DWN))
 $(eval $(call add_define,SKIP_A57_L1_FLUSH_PWR_DWN))
@@ -43,6 +47,9 @@ $(eval $(call add_define,WORKAROUND_CVE_2018_3639))
 $(eval $(call assert_boolean,DYNAMIC_WORKAROUND_CVE_2018_3639))
 $(eval $(call add_define,DYNAMIC_WORKAROUND_CVE_2018_3639))
 
+$(eval $(call assert_boolean,NEOVERSE_N1_EXTERNAL_LLC))
+$(eval $(call add_define,NEOVERSE_N1_EXTERNAL_LLC))
+
 ifneq (${DYNAMIC_WORKAROUND_CVE_2018_3639},0)
     ifeq (${WORKAROUND_CVE_2018_3639},0)
         $(error "Error: WORKAROUND_CVE_2018_3639 must be 1 if DYNAMIC_WORKAROUND_CVE_2018_3639 is 1")