fix(cpus): workaround for Cortex-A78C erratum 1827430

Cortex-A78C erratum 1827430 is a Cat B erratum that applies to
revision r0p0 and is fixed in r0p1.

The workaround is to set the CPUECTLR_EL1[53] to 1, which disables
allocation of splintered pages in the L2 TLB.

SDEN documentation:
https://developer.arm.com/documentation/SDEN1707916/latest

Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: Ie68771bdd3bddeff54d06b6a456dad4a7fc27426

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

@@ -349,6 +349,10 @@ For Cortex-A78 AE, the following errata build flags are defined :
 
 For Cortex-A78C, the following errata build flags are defined :
 
+- ``ERRATA_A78C_1827430`` : This applies errata 1827430 workaround to
+  Cortex-A78C CPU. This needs to be enabled for revision r0p0. The erratum is
+  fixed in r0p1.
+
 - ``ERRATA_A78C_2132064`` : This applies errata 2132064 workaround to
   Cortex-A78C CPU. This needs to be enabled for revisions r0p1, r0p2 and
   it is still open.

include/lib/cpus/aarch64/cortex_a78c.h

@@ -26,6 +26,7 @@
 #define CORTEX_A78C_CPUECTLR_EL1		        S3_0_C15_C1_4
 #define CORTEX_A78C_CPUECTLR_EL1_BIT_6		        (ULL(1) << 6)
 #define CORTEX_A78C_CPUECTLR_EL1_BIT_7		        (ULL(1) << 7)
+#define CORTEX_A78C_CPUECTLR_EL1_MM_ASP_EN		(ULL(1) << 53)
 
 /*******************************************************************************
  * CPU Power Control register specific definitions

lib/cpus/aarch64/cortex_a78c.S

@@ -17,6 +17,33 @@
 #error "cortex_a78c must be compiled with HW_ASSISTED_COHERENCY enabled"
 #endif
 
+/* --------------------------------------------------
+ * Errata Workaround for A78C Erratum 1827430.
+ * This applies to revision r0p0 of the Cortex A78C
+ * processor and is fixed in r0p1.
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * --------------------------------------------------
+ */
+func errata_a78c_1827430_wa
+	mov	x17, x30
+	bl	check_errata_1827430
+	cbz	x0, 1f
+
+	/* Disable allocation of splintered pages in the L2 TLB */
+	mrs	x1, CORTEX_A78C_CPUECTLR_EL1
+	orr	x1, x1, CORTEX_A78C_CPUECTLR_EL1_MM_ASP_EN
+	msr	CORTEX_A78C_CPUECTLR_EL1, x1
+1:
+	ret	x17
+endfunc errata_a78c_1827430_wa
+
+func check_errata_1827430
+	/* Applies to revision r0p0 only */
+	mov	x1, #0x00
+	b	cpu_rev_var_ls
+endfunc check_errata_1827430
+
 /* --------------------------------------------------
  * Errata Workaround for Cortex A78C Erratum 2376749.
  * This applies to revision r0p1 and r0p2 of the A78C
@@ -225,6 +252,11 @@ func cortex_a78c_reset_func
 	bl	cpu_get_rev_var
 	mov	x18, x0
 
+#if ERRATA_A78C_1827430
+	mov	x0, x18
+	bl	errata_a78c_1827430_wa
+#endif
+
 #if ERRATA_A78C_2132064
 	mov	x0, x18
 	bl	errata_a78c_2132064_wa
@@ -299,6 +331,7 @@ func cortex_a78c_errata_report
 	 * Report all errata. The revision-variant information is passed to
 	 * checking functions of each errata.
 	 */
+	report_errata ERRATA_A78C_1827430, cortex_a78c, 1827430
 	report_errata ERRATA_A78C_2132064, cortex_a78c, 2132064
 	report_errata ERRATA_A78C_2242638, cortex_a78c, 2242638
 	report_errata ERRATA_A78C_2376749, cortex_a78c, 2376749

lib/cpus/cpu-ops.mk

@@ -354,6 +354,10 @@ CPU_FLAG_LIST += ERRATA_A78_AE_2376748
 # to revisions r0p0 and r0p1 of the A78 AE cpu. It is still open.
 CPU_FLAG_LIST += ERRATA_A78_AE_2395408
 
+# Flag to apply erratum 1827430 workaround during reset. This erratum applies
+# to revision r0p0 of the A78C cpu. It is fixed in r0p1.
+CPU_FLAG_LIST += ERRATA_A78C_1827430
+
 # Flag to apply erratum 2132064 workaround during reset. This erratum applies
 # to revisions r0p1 and r0p2 of the A78C cpu. It is still open.
 CPU_FLAG_LIST += ERRATA_A78C_2132064