feat(plat/mediatek/mt8195): add EMI MPU basic drivers

EMI MPU stands for external memory interface memory protect unit.
MT8195 supports 32 regions and 16 domains.
We add basic drivers currently, and will add more setting for
EMI MPU in next patch.

Change-Id: Iedc19d8f6fcf1ceb2d8241319b8dc17c885642dd
diff --git a/plat/mediatek/mt8195/drivers/emi_mpu/emi_mpu.c b/plat/mediatek/mt8195/drivers/emi_mpu/emi_mpu.c
new file mode 100644
index 0000000..4330b77
--- /dev/null
+++ b/plat/mediatek/mt8195/drivers/emi_mpu/emi_mpu.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <string.h>
+#include <common/debug.h>
+#include <lib/mmio.h>
+#include <emi_mpu.h>
+
+#if ENABLE_EMI_MPU_SW_LOCK
+static unsigned char region_lock_state[EMI_MPU_REGION_NUM];
+#endif
+
+#define EMI_MPU_START_MASK		(0x00FFFFFF)
+#define EMI_MPU_END_MASK		(0x00FFFFFF)
+#define EMI_MPU_APC_SW_LOCK_MASK	(0x00FFFFFF)
+#define EMI_MPU_APC_HW_LOCK_MASK	(0x80FFFFFF)
+
+static int _emi_mpu_set_protection(unsigned int start, unsigned int end,
+					unsigned int apc)
+{
+	unsigned int dgroup;
+	unsigned int region;
+
+	region = (start >> 24) & 0xFF;
+	start &= EMI_MPU_START_MASK;
+	dgroup = (end >> 24) & 0xFF;
+	end &= EMI_MPU_END_MASK;
+
+	if  ((region >= EMI_MPU_REGION_NUM) || (dgroup > EMI_MPU_DGROUP_NUM)) {
+		WARN("invalid region, domain\n");
+		return -1;
+	}
+
+#if ENABLE_EMI_MPU_SW_LOCK
+	if (region_lock_state[region] == 1) {
+		WARN("invalid region\n");
+		return -1;
+	}
+
+	if ((dgroup == 0) && ((apc >> 31) & 0x1)) {
+		region_lock_state[region] = 1;
+	}
+
+	apc &= EMI_MPU_APC_SW_LOCK_MASK;
+#else
+	apc &= EMI_MPU_APC_HW_LOCK_MASK;
+#endif
+
+	if ((start >= DRAM_OFFSET) && (end >= start)) {
+		start -= DRAM_OFFSET;
+		end -= DRAM_OFFSET;
+	} else {
+		WARN("invalid range\n");
+		return -1;
+	}
+
+	mmio_write_32(EMI_MPU_SA(region), start);
+	mmio_write_32(EMI_MPU_EA(region), end);
+	mmio_write_32(EMI_MPU_APC(region, dgroup), apc);
+
+#if defined(SUB_EMI_MPU_BASE)
+	mmio_write_32(SUB_EMI_MPU_SA(region), start);
+	mmio_write_32(SUB_EMI_MPU_EA(region), end);
+	mmio_write_32(SUB_EMI_MPU_APC(region, dgroup), apc);
+#endif
+	return 1;
+}
+
+int emi_mpu_set_protection(struct emi_region_info_t *region_info)
+{
+	unsigned int start, end;
+	int i;
+
+	if (region_info->region >= EMI_MPU_REGION_NUM) {
+		WARN("invalid region\n");
+		return -1;
+	}
+
+	start = (unsigned int)(region_info->start >> EMI_MPU_ALIGN_BITS) |
+		(region_info->region << 24);
+
+	for (i = EMI_MPU_DGROUP_NUM - 1; i >= 0; i--) {
+		end = (unsigned int)(region_info->end >> EMI_MPU_ALIGN_BITS) |
+			(i << 24);
+		_emi_mpu_set_protection(start, end, region_info->apc[i]);
+	}
+
+	return 0;
+}
+
+void emi_mpu_init(void)
+{
+	/* TODO: more setting for EMI MPU. */
+}