arm: Support cache invalidate

At present there is not operation to invalidate a cache range. This seems
to be needed to fill out the cache operations. Add an implementation based
on the flush operation.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: York Sun <york.sun@nxp.com>

arch/arm/cpu/armv8/cache.S

@@ -138,6 +138,30 @@ ENTRY(__asm_flush_dcache_range)
 	dsb	sy
 	ret
 ENDPROC(__asm_flush_dcache_range)
+/*
+ * void __asm_invalidate_dcache_range(start, end)
+ *
+ * invalidate data cache in the range
+ *
+ * x0: start address
+ * x1: end address
+ */
+ENTRY(__asm_invalidate_dcache_range)
+	mrs	x3, ctr_el0
+	ubfm	x3, x3, #16, #19
+	mov	x2, #4
+	lsl	x2, x2, x3		/* cache line size */
+
+	/* x2 <- minimal cache line size in cache system */
+	sub	x3, x2, #1
+	bic	x0, x0, x3
+1:	dc	ivac, x0	/* invalidate data or unified cache */
+	add	x0, x0, x2
+	cmp	x0, x1
+	b.lo	1b
+	dsb	sy
+	ret
+ENDPROC(__asm_invalidate_dcache_range)
 
 /*
  * void __asm_invalidate_icache_all(void)

arch/arm/cpu/armv8/cache_v8.c

@@ -446,7 +446,7 @@ inline void flush_dcache_all(void)
  */
 void invalidate_dcache_range(unsigned long start, unsigned long stop)
 {
-	__asm_flush_dcache_range(start, stop);
+	__asm_invalidate_dcache_range(start, stop);
 }
 
 /*

arch/arm/include/asm/system.h

@@ -180,6 +180,21 @@ static inline unsigned long read_mpidr(void)
 void __asm_flush_dcache_all(void);
 void __asm_invalidate_dcache_all(void);
 void __asm_flush_dcache_range(u64 start, u64 end);
+
+/**
+ * __asm_invalidate_dcache_range() - Invalidate a range of virtual addresses
+ *
+ * This performance an invalidate from @start to @end - 1. Both addresses
+ * should be cache-aligned, otherwise this function will align the start
+ * address and may continue past the end address.
+ *
+ * Data in the address range is evicted from the cache and is not written back
+ * to memory.
+ *
+ * @start: Start address to invalidate
+ * @end: End address to invalidate up to (exclusive)
+ */
+void __asm_invalidate_dcache_range(u64 start, u64 end);
 void __asm_invalidate_tlb_all(void);
 void __asm_invalidate_icache_all(void);
 int __asm_invalidate_l3_dcache(void);