arm64: mvebu: Add L3 cache flush functionality to A8K family

Add missing L3 cache flush functionality which absence prevents
Linux kernel from normal boot in case the L3 cache is enabled
by ATF.
The L3 cache is named the "last level" cache in order to keep
the terminology similar to the ATF code.
This cache should not be disabled by u-boot since the Linux
kernel cannot activate it, so it is activates at ATF stage.
However the cache flush is required for preventing data corruption
after disabling the MMU and the data cache before passing control
to the loaded Linux image.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Neta Zur Hershkovits <neta@marvell.com>
Cc: Omri Itach <omrii@marvell.com>
Cc: Igal Liberman <igall@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>

arch/arm/include/asm/arch-armada8k/cache_llc.h

+/*
+ * Copyright (C) 2016 Marvell International Ltd.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ * https://spdx.org/licenses
+ */
+
+#ifndef _CACHE_LLC_H_
+#define _CACHE_LLC_H_
+
+/* Armada-7K/8K last level cache */
+
+#define MVEBU_A8K_REGS_BASE_MSB		0xf000
+#define LLC_BASE_ADDR			0x8000
+#define LLC_CACHE_SYNC			0x700
+#define LLC_CACHE_SYNC_COMPLETE		0x730
+#define LLC_FLUSH_BY_WAY		0x7fc
+#define LLC_WAY_MASK			0xffffffff
+#define LLC_CACHE_SYNC_MASK		0x1
+
+#endif	/* _CACHE_LLC_H_ */

arch/arm/mach-mvebu/armada8k/Makefile

@@ -5,3 +5,4 @@
 #
 
 obj-y = cpu.o
+obj-y += cache_llc.o

arch/arm/mach-mvebu/armada8k/cache_llc.S

+/*
+ * Copyright (C) 2016 Marvell International Ltd.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ * https://spdx.org/licenses
+ */
+
+#include <asm/arch-armada8k/cache_llc.h>
+#include <linux/linkage.h>
+
+/*
+ * int __asm_flush_l3_dcache
+ *
+ * flush Armada-8K last level cache.
+ *
+ */
+ENTRY(__asm_flush_l3_dcache)
+	/* flush cache */
+	mov     x0, #LLC_BASE_ADDR
+	add	x0, x0, #LLC_FLUSH_BY_WAY
+	movk    x0, #MVEBU_A8K_REGS_BASE_MSB, lsl #16
+	mov     w1, #LLC_WAY_MASK
+	str     w1, [x0]
+	/* sync cache */
+	mov     x0, #LLC_BASE_ADDR
+	add	x0, x0, #LLC_CACHE_SYNC
+	movk    x0, #MVEBU_A8K_REGS_BASE_MSB, lsl #16
+	str     wzr, [x0]
+	/* check that cache sync completed */
+	mov     x0, #LLC_BASE_ADDR
+	add	x0, x0, #LLC_CACHE_SYNC_COMPLETE
+	movk    x0, #MVEBU_A8K_REGS_BASE_MSB, lsl #16
+1:	ldr	w1, [x0]
+	and	w1, w1, #LLC_CACHE_SYNC_MASK
+	cbnz	w1, 1b
+	/* return success */
+	mov	x0, #0
+	ret
+ENDPROC(__asm_flush_l3_dcache)