Implement systick module

drv/stk.c

@@ -0,0 +1,84 @@
+/** @file stk.c
+ * Module handling the system timer (systick or STK for short)
+ *
+ * The module provides functions to configure and use the system timer embedded
+ * in the cortex m core
+ */
+
+//--includes--------------------------------------------------------------------
+
+#include "stk.h"
+#include "stk_regs.h"
+
+#include "rcc.h"
+
+
+//--local definitions-----------------------------------------------------------
+
+static volatile struct STK* regs = (struct STK*)STK_BASE_ADDRESS;
+
+//--local variables-------------------------------------------------------------
+
+static StkCallback callback;
+
+
+//--public functions------------------------------------------------------------
+
+uint32_t stk_configure(uint32_t period_us, StkCallback cb)
+{
+	stk_reset();
+
+	struct RccClocks clocks;
+	rcc_get_clocks(&clocks);
+
+	uint32_t reload = period_us * (clocks.ahb_freq / 1000000 / 8);
+	if (reload < 1) {
+		//period is too small, try using the non-prescaled clock
+		reload = period_us * (clocks.ahb_freq / 1000000);
+		if (reload < 1) {
+			//period is still too small
+			return 1;
+		}
+		reg_set(regs->CTRL, STK_CTRL_CLKSOURCE);
+	}
+	reg_write(regs->LOAD, STK_LOAD_RELOAD, reload);
+	reg_set(regs->CTRL, STK_CTRL_TICKINT);
+
+	callback = cb;
+
+	return 0;
+}
+
+void stk_reset(void)
+{
+	reg_reset(regs->CTRL, STK_CTRL_ENABLE);
+	reg_reset(regs->CTRL, STK_CTRL_TICKINT);
+	reg_reset(regs->CTRL, STK_CTRL_CLKSOURCE);
+	reg_reset(regs->CTRL, STK_CTRL_COUNTFLAG);
+
+	reg_write(regs->LOAD, STK_LOAD_RELOAD, 0);
+	reg_write(regs->VAL, STK_VAL_CURRENT, 0);
+}
+
+void stk_start(void)
+{
+	reg_set(regs->CTRL, STK_CTRL_ENABLE);
+}
+
+void stk_stop(void)
+{
+	reg_reset(regs->CTRL, STK_CTRL_ENABLE);
+}
+
+uint32_t stk_read(void)
+{
+	return regs->VAL.word & 0x00FFFFFF;
+}
+
+
+//--local functions-------------------------------------------------------------
+
+void hdr_sys_tick(void)
+{
+	callback();
+}

drv/stk.h

@@ -0,0 +1,31 @@
+/** @file stk.h
+ * Module handling the system timer (systick or STK for short)
+ *
+ * The module provides functions to configure and use the system timer embedded
+ * in the cortex m core
+ */
+
+#ifndef _STK_H_
+#define _STK_H_
+
+//--includes--------------------------------------------------------------------
+
+#include <stdint.h>
+
+
+//--type definitions------------------------------------------------------------
+
+typedef void (*StkCallback)(void);
+
+
+//--functions-------------------------------------------------------------------
+
+uint32_t stk_configure(uint32_t period_us, StkCallback cb);
+void stk_reset(void);
+void stk_start(void);
+void stk_stop(void);
+uint32_t stk_read(void);
+
+
+#endif //_STK_H_
+