feat(cpus): add more errata framework helpers

Figuring out the naming format of errata is annoying, so add a shorthand
for the custom checker functions. Also add some more semantic macros
instead of passing around constants.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: Ibdcf72146738026df4ebd047bfb30790fd4a1053

include/lib/cpus/aarch64/cpu_macros.S

@@ -426,6 +426,23 @@
 	msr	\_reg, x1
 .endm
 
+/*
+ * Clear a bit in a system register. Can clear multiple bits but is limited by
+ *  the way the BIC instrucion encodes them.
+ *
+ * see sysreg_bit_set for usage
+ */
+.macro sysreg_bit_clear _reg:req, _bit:req
+	mrs	x1, \_reg
+	bic	x1, x1, #\_bit
+	msr	\_reg, x1
+.endm
+
+.macro override_vector_table _table:req
+	adr	x1, \_table
+	msr	vbar_el3, x1
+.endm
+
 /*
  * Apply erratum
  *
@@ -497,6 +514,27 @@
 	endfunc check_erratum_\_cpu\()_\_id
 .endm
 
+.macro check_erratum_chosen _cpu:req, _cve:req, _id:req, _chosen:req
+	func check_erratum_\_cpu\()_\_id
+		.if \_chosen
+			mov	x0, #ERRATA_APPLIES
+		.else
+			mov	x0, #ERRATA_MISSING
+		.endif
+		ret
+	endfunc check_erratum_\_cpu\()_\_id
+.endm
+
+/* provide a shorthand for the name format for annoying errata */
+.macro check_erratum_custom_start _cpu:req, _cve:req, _id:req
+	func check_erratum_\_cpu\()_\_id
+.endm
+
+.macro check_erratum_custom_end _cpu:req, _cve:req, _id:req
+	endfunc check_erratum_\_cpu\()_\_id
+.endm
+
+
 /*******************************************************************************
  * CPU reset function wrapper
  ******************************************************************************/

include/lib/cpus/errata.h

@@ -64,6 +64,10 @@ CASSERT(sizeof(struct erratum_entry) == ERRATUM_ENTRY_SIZE,
 #define CVE(year, id)		year, id
 #define NO_ISB			1
 #define NO_ASSERT		0
+#define NO_APPLY_AT_RESET	0
+#define APPLY_AT_RESET		1
+/* useful for errata that end up always being worked around */
+#define ERRATUM_ALWAYS_CHOSEN	1
 
 #endif /* __ASSEMBLER__ */