fix(errata): workaround for Cortex-A510 erratum 2371937

Cortex-A510 erratum 2371937 is a Cat B erratum that applies
to revisions r0p0, r0p1, r0p2, r0p3, r1p0, and r1p1. It is
fixed in r1p2. The workaround is to set the ATOM field of
CPUECTLR_EL1 (bits [40:38]) to 0b010, which will force all
cacheable atomic operations to be executed near.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1873351/latest
https://developer.arm.com/documentation/SDEN1873361/latest

Signed-off-by: Akram Ahmad <Akram.Ahmad@arm.com>
Change-Id: Ia219a609a3397e39631de65831ecff8a3cd1227e

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

@@ -589,6 +589,10 @@ For Cortex-A510, the following errata build flags are defined :
    Cortex-A510 CPU. This needs to be enabled for revisions r0p0, r0p1, r0p2,
    r0p3 and r1p0, it is fixed in r1p1.
 
+-  ``ERRATA_A510_2371937``: This applies errata 2371937 workaround to
+   Cortex-A510 CPU. This needs to applied for revisions r0p0, r0p1, r0p2,
+   r0p3, r1p0, r1p1, and is fixed in r1p2.
+
 DSU Errata Workarounds
 ----------------------
 

include/lib/cpus/aarch64/cortex_a510.h

@@ -17,6 +17,8 @@
 #define CORTEX_A510_CPUECTLR_EL1_READPREFERUNIQUE_DISABLE	U(1)
 #define CORTEX_A510_CPUECTLR_EL1_RSCTL_SHIFT			U(23)
 #define CORTEX_A510_CPUECTLR_EL1_NTCTL_SHIFT			U(46)
+#define CORTEX_A510_CPUECTLR_EL1_ATOM_EXECALLINSTRNEAR		U(2)
+#define CORTEX_A510_CPUECTLR_EL1_ATOM				U(38)
 
 /*******************************************************************************
  * CPU Power Control register specific definitions

lib/cpus/aarch64/cortex_a510.S

@@ -264,6 +264,40 @@ func check_errata_2172148
 	b	cpu_rev_var_ls
 endfunc check_errata_2172148
 
+	/*---------------------------------------------------
+	 * Errata Workaround for Cortex-A510 Errata #2371937.
+	 * This applies to revisions r1p1 and lower, and is
+	 * fixed in r1p2.
+	 * Inputs:
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0, x1, x17
+	 *---------------------------------------------------
+	 */
+func errata_cortex_a510_2371937_wa
+	mov	x17, x30
+	bl	check_errata_2371937
+	cbz	x0, 1f
+
+	/*
+	 * Cacheable atomic operations can be forced
+	 * to be executed near by setting
+	 * IMP_CPUECTLR_EL1.ATOM=0b010. ATOM is found
+	 * in [40:38] of CPUECTLR_EL1.
+	 */
+	mrs 	x0, CORTEX_A510_CPUECTLR_EL1
+	mov 	x1, CORTEX_A510_CPUECTLR_EL1_ATOM_EXECALLINSTRNEAR
+	bfi 	x0, x1, CORTEX_A510_CPUECTLR_EL1_ATOM, #3
+	msr 	CORTEX_A510_CPUECTLR_EL1, x0
+1:
+	ret 	x17
+endfunc errata_cortex_a510_2371937_wa
+
+func check_errata_2371937
+	/* Applies to r1p1 and lower */
+	mov 	x1, #0x11
+	b	cpu_rev_var_ls
+endfunc check_errata_2371937
+
 	/* ----------------------------------------------------
 	 * HW will do the cache maintenance while powering down
 	 * ----------------------------------------------------
@@ -301,6 +335,7 @@ func cortex_a510_errata_report
 	report_errata ERRATA_A510_2250311, cortex_a510, 2250311
 	report_errata ERRATA_A510_2218950, cortex_a510, 2218950
 	report_errata ERRATA_A510_2172148, cortex_a510, 2172148
+	report_errata ERRATA_A510_2371937, cortex_a510, 2371937
 	report_errata ERRATA_DSU_2313941, cortex_a510, dsu_2313941
 
 	ldp	x8, x30, [sp], #16
@@ -352,6 +387,11 @@ func cortex_a510_reset_func
 	bl	errata_cortex_a510_2218950_wa
 #endif
 
+#if ERRATA_A510_2371937
+	mov 	x0, x18
+	bl	errata_cortex_a510_2371937_wa
+#endif
+
 #if ERRATA_A510_2172148
 	mov	x0, x18
 	bl	errata_cortex_a510_2172148_wa

lib/cpus/cpu-ops.mk

@@ -645,6 +645,10 @@ ERRATA_A510_2218950	?=0
 # to revisions r0p0, r0p1, r0p2, r0p3 and r1p0, and is fixed in r1p1.
 ERRATA_A510_2172148	?=0
 
+# Flag to apply erratum 2371937 workaround during reset. This erratum applies
+# to revisions r0p0, r0p1, r0p2, r0p3, r1p0, and r1p1. It is fixed in r1p2.
+ERRATA_A510_2371937	?=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
@@ -1215,6 +1219,10 @@ $(eval $(call add_define,ERRATA_A510_2218950))
 $(eval $(call assert_boolean,ERRATA_A510_2172148))
 $(eval $(call add_define,ERRATA_A510_2172148))
 
+# Process ERRATA_A510_2371937 flag
+$(eval $(call assert_boolean,ERRATA_A510_2371937))
+$(eval $(call add_define,ERRATA_A510_2371937))
+
 # Process ERRATA_DSU_798953 flag
 $(eval $(call assert_boolean,ERRATA_DSU_798953))
 $(eval $(call add_define,ERRATA_DSU_798953))