Port to QEMU netduino2 (cortex-m3)

1 files changed, 73 insertions, 0 deletions

diff --git a/src/systick.c b/src/systick.c
new file mode 100644
index 0000000..1307d98
--- /dev/null
+++ b/src/systick.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2018 Richard Braun.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+#include "panic.h"
+#include "systick.h"
+#include "thread.h"
+
+#define SYSTICK_BASE_ADDR 0xe000e010
+
+#define SYSTICK_CSR_ENABLE  0x1
+#define SYSTICK_CSR_TICKINT 0x2
+
+#define SYSTICK_CALIB_NOREF         0x80000000
+#define SYSTICK_CALIB_SKEW          0x40000000
+#define SYSTICK_CALIB_TENMS_MASK    0x00ffffff
+
+struct systick_regs {
+    uint32_t csr;
+    uint32_t rvr;
+    uint32_t cvr;
+    uint32_t calib;
+};
+
+static volatile struct systick_regs *systick_regs = (void *)SYSTICK_BASE_ADDR;
+
+static void
+systick_check_calib(void)
+{
+    uint32_t calib;
+
+    calib = systick_regs->calib;
+
+    if ((calib & SYSTICK_CALIB_NOREF)
+        || (calib & SYSTICK_CALIB_SKEW)
+        || (calib & SYSTICK_CALIB_TENMS_MASK) == 0) {
+        panic("systick: unusable");
+    }
+}
+
+void
+systick_setup(void)
+{
+    uint32_t tenms, counter;
+
+    systick_check_calib();
+
+    tenms = systick_regs->calib & SYSTICK_CALIB_TENMS_MASK;
+    counter = (tenms * 100) / THREAD_SCHED_FREQ;
+    systick_regs->rvr = counter;
+    systick_regs->cvr = 0;
+    systick_regs->csr = (SYSTICK_CSR_TICKINT | SYSTICK_CSR_ENABLE);
+}