1 files changed, 98 insertions, 0 deletions
diff --git a/src/stopwatch.c b/src/stopwatch.c
new file mode 100644
index 0000000..4f4a961
--- /dev/null
+++ b/src/stopwatch.c
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <m0_param.h>
+#include "rk3399_mcu.h"
+
+/* use 24MHz SysTick */
+#define US_TO_CYCLE(US)	(US * 24)
+
+#define SYST_CST	0xe000e010
+/* enable counter */
+#define ENABLE		(1 << 0)
+/* count down to 0 does not cause SysTick exception to pend */
+#define TICKINT		(1 << 1)
+/* core clock used for SysTick */
+#define CLKSOURCE	(1 << 2)
+
+#define COUNTFLAG	(1 << 16)
+#define SYST_RVR	0xe000e014
+#define MAX_VALUE	0xffffff
+#define MAX_USECS	(MAX_VALUE / US_TO_CYCLE(1))
+#define SYST_CVR	0xe000e018
+#define SYST_CALIB	0xe000e01c
+
+unsigned int remaining_usecs;
+
+static inline void stopwatch_set_usecs(void)
+{
+	unsigned int cycle;
+	unsigned int usecs = MIN(MAX_USECS, remaining_usecs);
+
+	remaining_usecs -= usecs;
+	cycle = US_TO_CYCLE(usecs);
+	mmio_write_32(SYST_RVR, cycle);
+	mmio_write_32(SYST_CVR, 0);
+
+	mmio_write_32(SYST_CST, ENABLE | TICKINT | CLKSOURCE);
+}
+
+void stopwatch_init_usecs_expire(unsigned int usecs)
+{
+	/*
+	 * Enter an inifite loop if the stopwatch is in use. This will allow the
+	 * state to be analyzed with a debugger.
+	 */
+	if (mmio_read_32(SYST_CST) & ENABLE)
+		while (1)
+			;
+
+	remaining_usecs = usecs;
+	stopwatch_set_usecs();
+}
+
+int stopwatch_expired(void)
+{
+	int val = mmio_read_32(SYST_CST);
+	if ((val & COUNTFLAG) || !(val & ENABLE)) {
+		if (!remaining_usecs)
+			return 1;
+
+		stopwatch_set_usecs();
+	}
+
+	return 0;
+}
+
+void stopwatch_reset(void)
+{
+	mmio_clrbits_32(SYST_CST, ENABLE);
+	remaining_usecs = 0;
+}