mediatek: mt8192: add timer support

add timer driver.

Change-Id: I07448d85a15bb14577b05e4f302860d609420ba7
diff --git a/plat/mediatek/mt8192/drivers/timer/mt_timer.c b/plat/mediatek/mt8192/drivers/timer/mt_timer.c
new file mode 100644
index 0000000..781f940
--- /dev/null
+++ b/plat/mediatek/mt8192/drivers/timer/mt_timer.c
@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2020, MediaTek Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <mt_timer.h>
+#include <platform_def.h>
+
+
+uint64_t normal_time_base;
+uint64_t atf_time_base;
+
+void sched_clock_init(uint64_t normal_base, uint64_t atf_base)
+{
+	normal_time_base += normal_base;
+	atf_time_base = atf_base;
+}
+
+uint64_t sched_clock(void)
+{
+	uint64_t cval;
+	uint64_t rel_base;
+
+	rel_base = read_cntpct_el0() - atf_time_base;
+	cval = ((rel_base * 1000U) / SYS_COUNTER_FREQ_IN_MHZ)
+		- normal_time_base;
+	return cval;
+}