Add ARM errata workaround 852421 and 852423 for Cortex-A17

ARM errata 852421 and 852423 applies to r1p0, r1p1 and r1p2
revisions of Cortex-A17 processors. These workarounds
exist in Linux kernel and I thought it would be better
to add them in to U-Boot.

Signed-off-by: Nisal Menuka <nisalmenuka23@gmail.com>

arch/arm/Kconfig

@@ -88,6 +88,12 @@ config ARM_ERRATA_833069
 config ARM_ERRATA_833471
 	bool
 
+config ARM_ERRATA_852421
+	bool
+
+config ARM_ERRATA_852423
+	bool
+
 config CPU_ARM720T
 	bool
 	select SYS_CACHE_SHIFT_5

arch/arm/cpu/armv7/start.S

@@ -283,6 +283,18 @@ skip_errata_621766:
 skip_errata_725233:
 #endif
 
+#ifdef CONFIG_ARM_ERRATA_852421
+	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
+	orr	r0, r0, #1 << 24	@ set bit #24
+	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
+#endif
+
+#ifdef CONFIG_ARM_ERRATA_852423
+	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
+	orr	r0, r0, #1 << 12	@ set bit #12
+	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
+#endif
+
 	mov	pc, r5			@ back to my caller
 ENDPROC(cpu_init_cp15)