ARM: Introduce erratum workaround for 621766

621766: Under a specific set of conditions, executing a sequence of
	NEON or vfp load instructions can cause processor deadlock
Impacts: Every Cortex-A8 processors with revision lower than r2p1
Work around: Set L1NEON to 1

Based on ARM errata Document revision 20.0 (13 Nov 2010)

Signed-off-by: Nishanth Menon <nm@ti.com>
Tested-by: Matt Porter <mporter@konsulko.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

README

@@ -695,6 +695,7 @@ The following options need to be configured:
 		specific checks, but expect no product checks.
 		CONFIG_ARM_ERRATA_430973
 		CONFIG_ARM_ERRATA_454179
+		CONFIG_ARM_ERRATA_621766
 		CONFIG_ARM_ERRATA_798870
 
 - Tegra SoC options:

arch/arm/cpu/armv7/start.S

@@ -213,6 +213,19 @@ skip_errata_454179:
 	pop	{r1-r5}			@ Restore the cpu info - fall through
 
 skip_errata_430973:
+#endif
+
+#ifdef CONFIG_ARM_ERRATA_621766
+	cmp	r2, #0x21		@ Only on < r2p1
+	bge	skip_errata_621766
+
+	mrc	p15, 0, r0, c1, c0, 1	@ Read ACR
+	orr	r0, r0, #(0x1 << 5)	@ Set L1NEON bit
+	push	{r1-r5}			@ Save the cpu info registers
+	bl	v7_arch_cp15_set_acr
+	pop	{r1-r5}			@ Restore the cpu info - fall through
+
+skip_errata_621766:
 #endif
 
 	mov	pc, r5			@ back to my caller