From f8e7bb03ca44710b753e8a0d5bf78932e97abb3e Mon Sep 17 00:00:00 2001
From: Hudson Ayers <hayers@stanford.edu>
Date: Sun, 31 Mar 2024 22:30:51 -0700
Subject: [PATCH] Add cycle counter driver and test app

---
 examples/tests/cycle_count/Makefile  | 11 +++++++++
 examples/tests/cycle_count/README.md |  5 ++++
 examples/tests/cycle_count/main.c    | 36 ++++++++++++++++++++++++++++
 libtock/cycle_counter.c              | 29 ++++++++++++++++++++++
 libtock/cycle_counter.h              | 19 +++++++++++++++
 5 files changed, 100 insertions(+)
 create mode 100644 examples/tests/cycle_count/Makefile
 create mode 100644 examples/tests/cycle_count/README.md
 create mode 100644 examples/tests/cycle_count/main.c
 create mode 100644 libtock/cycle_counter.c
 create mode 100644 libtock/cycle_counter.h

diff --git a/examples/tests/cycle_count/Makefile b/examples/tests/cycle_count/Makefile
new file mode 100644
index 000000000..54d6a7969
--- /dev/null
+++ b/examples/tests/cycle_count/Makefile
@@ -0,0 +1,11 @@
+# Makefile for user application
+
+# Specify this directory relative to the current application.
+TOCK_USERLAND_BASE_DIR = ../../..
+
+# Which files to compile.
+C_SRCS := $(wildcard *.c)
+
+# Include userland master makefile. Contains rules and flags for actually
+# building the application.
+include $(TOCK_USERLAND_BASE_DIR)/AppMakefile.mk
diff --git a/examples/tests/cycle_count/README.md b/examples/tests/cycle_count/README.md
new file mode 100644
index 000000000..ae552f58d
--- /dev/null
+++ b/examples/tests/cycle_count/README.md
@@ -0,0 +1,5 @@
+Test `cycle_count`
+====================
+
+This tests the cycle counter capsule.
+It will print the number of cycles required to toggle an LED.
diff --git a/examples/tests/cycle_count/main.c b/examples/tests/cycle_count/main.c
new file mode 100644
index 000000000..6658018f2
--- /dev/null
+++ b/examples/tests/cycle_count/main.c
@@ -0,0 +1,36 @@
+#include <stdio.h>
+
+#include <cycle_counter.h>
+#include <led.h>
+#include <tock.h>
+
+int main(void) {
+  uint64_t cycles = 0;
+
+  int rc = cycle_counter_reset();
+  if (rc == RETURNCODE_ENOSUPPORT) {
+    printf("Cycle counter not available\n");
+  } else if (rc == RETURNCODE_ERESERVE) {
+    printf("Cycle counter claimed by another app\n");
+  } else if (rc != 0) {
+    printf("Cycle counter: other error: %d\n", rc);
+  }
+
+  if (rc != 0) {
+    return 0;
+  }
+
+  cycle_counter_start();
+  led_toggle(0);
+  cycle_counter_stop();
+  cycle_counter_read(&cycles);
+  printf("cycles to toggle led first time: %d\n", cycles);
+
+  cycle_counter_reset();
+  cycle_counter_start();
+  led_toggle(0);
+  cycle_counter_stop();
+  cycle_counter_read(&cycles);
+  printf("cycles to toggle led second time: %d\n", cycles);
+  return 0;
+}
diff --git a/libtock/cycle_counter.c b/libtock/cycle_counter.c
new file mode 100644
index 000000000..d7887a0aa
--- /dev/null
+++ b/libtock/cycle_counter.c
@@ -0,0 +1,29 @@
+#include "cycle_counter.h"
+
+bool cycle_counter_exists(void) {
+  return driver_exists(DRIVER_NUM_CYCLE_COUNTER);
+}
+
+// Start the cycle counter
+int cycle_counter_start(void) {
+  syscall_return_t rval = command(DRIVER_NUM_CYCLE_COUNTER, 1, 0, 0);
+  return tock_command_return_novalue_to_returncode(rval);
+}
+
+// Get the current cycle count
+int cycle_counter_read(uint64_t* count) {
+  syscall_return_t rval = command(DRIVER_NUM_CYCLE_COUNTER, 2, 0, 0);
+  return tock_command_return_u64_to_returncode(rval, (uint64_t*) count);
+}
+
+// Reset the cycle counter
+int cycle_counter_reset(void) {
+  syscall_return_t rval = command(DRIVER_NUM_CYCLE_COUNTER, 3, 0, 0);
+  return tock_command_return_novalue_to_returncode(rval);
+}
+
+// Stop the cycle counter
+int cycle_counter_stop(void) {
+  syscall_return_t rval = command(DRIVER_NUM_CYCLE_COUNTER, 4, 0, 0);
+  return tock_command_return_novalue_to_returncode(rval);
+}
diff --git a/libtock/cycle_counter.h b/libtock/cycle_counter.h
new file mode 100644
index 000000000..a39057abb
--- /dev/null
+++ b/libtock/cycle_counter.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include "tock.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define DRIVER_NUM_CYCLE_COUNTER 0x00090008
+
+bool cycle_counter_exists(void);
+int cycle_counter_start(void);
+int cycle_counter_stop(void);
+int cycle_counter_reset(void);
+int cycle_counter_read(int *count);
+
+#ifdef __cplusplus
+}
+#endif