创建，添加sdram

rt-thread/components/drivers/ktime/src/aarch64/cputimer.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2006-2023, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-07-10     xqyjlj       The first version.
+ */
+
+#include "gtimer.h"
+#include "ktime.h"
+
+static volatile unsigned long _init_cnt = 0;
+
+unsigned long rt_ktime_cputimer_getres(void)
+{
+    return ((1000UL * 1000 * 1000) * RT_KTIME_RESMUL) / rt_hw_get_gtimer_frq();
+}
+
+unsigned long rt_ktime_cputimer_getfrq(void)
+{
+    return rt_hw_get_gtimer_frq();
+}
+
+unsigned long rt_ktime_cputimer_getcnt(void)
+{
+    return rt_hw_get_cntpct_val() - _init_cnt;
+}
+
+unsigned long rt_ktime_cputimer_getstep(void)
+{
+    return rt_ktime_cputimer_getfrq() / RT_TICK_PER_SECOND;
+}
+
+void rt_ktime_cputimer_init(void)
+{
+    _init_cnt = rt_hw_get_cntpct_val();
+}