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bertos/cpu/avr/drv/timer_xmega.c

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+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2005, 2010 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 2011 Onno <developer@gorgoz.org>
+ *
+ * -->
+ *
+ * \author Onno <developer@gorgoz.org>
+ *
+ * \brief Low-level timer module for AVR XMEGA (implementation).
+ *
+ * This file is heavily inspired by the AVR implementation for BeRTOS,
+ * but uses a different approach for implementing the different debug
+ * ports, by using the timer structs.
+ *
+ * This module is automatically included so no need to include
+ * in test list.
+ * notest: all
+ */
+
+#include <drv/timer_xmega.h>
+#include <cfg/macros.h> // BV()
+
+#include <cpu/types.h>
+#include <cpu/irq.h>
+
+#include <avr/io.h>
+
+/* Helper MACROS taken from the Atmel examples and altered
+ *
+ *  The AVR XMEGA has different structures for TC0 and TC1,
+ *  however these only differ in the amount of compare/capture
+ *  channels, so for this purpose they can be used exactly the same
+  */
+
+//check if the bitvalues of the TC0 and TC1 Timer/Counters are really the same
+#if TC0_CLKSEL_gm != TC1_CLKSEL_gm || TC0_WGMODE_gm != TC1_WGMODE_gm || TC0_OVFINTLVL_gm != TC1_OVFINTLVL_gm
+	#error TC0 and TC1 Timer/Counters cannot be configured with the same bitvalues
+#endif
+
+#define TIMER_CONFIG_CLOCK_SOURCE(_clkSel)\
+	((TIMERCOUNTER).CTRLA = ((TIMERCOUNTER).CTRLA & ~TC0_CLKSEL_gm) | _clkSel)
+
+#define TIMER_CLEAR_FLAGS() ((TIMERCOUNTER).INTFLAGS = 0xFF)
+
+#define TIMER_SET_PERIOD( _period ) ( (TIMERCOUNTER).PER = (_period) )
+
+#define TIMER_SET_OVERFLOW_INTERRUPT_LEVEL( _interruptLevel )\
+	((TIMERCOUNTER).INTCTRLA = ( (TIMERCOUNTER).INTCTRLA & ~TC0_OVFINTLVL_gm ) | _interruptLevel)
+
+#define TIMER_CONFIG_WGM(_wgm)\
+	((TIMERCOUNTER).CTRLB = ( (TIMERCOUNTER).CTRLB & ~TC0_WGMODE_gm ) | _wgm)
+
+#define TIMER_RESET() ( (TIMERCOUNTER).CTRLFSET = TC_CMD_RESET_gc )
+
+//Define TIMER_PRESCALE_REG_VALUE bases on the provided
+//TIMER_PRESCALER value
+#if TIMER_PRESCALER == 0
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_OFF_gc
+#elif TIMER_PRESCALER == 1
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV1_gc
+#elif TIMER_PRESCALER == 2
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV2_gc
+#elif TIMER_PRESCALER == 4
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV4_gc
+#elif TIMER_PRESCALER == 16
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV16_gc
+#elif TIMER_PRESCALER == 64
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV64_gc
+#elif TIMER_PRESCALER == 256
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV256_gc
+#elif TIMER_PRESCALER == 1024
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV1024_gc
+#else
+	#error Invalid value for TIMER_PRESCALER has been defined! Using default of 1
+	#define TIMER_CLKSEL_gc				TC_CLKSEL_DIV1_gc
+#endif
+
+void timer_hw_init(void)
+{
+	//Save and disable IRQ
+	cpu_flags_t flags;
+	IRQ_SAVE_DISABLE(flags);
+	//disable the timer
+	TIMER_CONFIG_CLOCK_SOURCE(TC_CLKSEL_OFF_gc);
+	//clear all flags
+	TIMER_CLEAR_FLAGS();
+	//setup the Periode register value
+	//CNT register will be reset to 0 when CNT == PER
+	TIMER_SET_PERIOD(TIMER_PERIOD_VALUE);
+	//set the Waveform Generation Mode to Normal
+	TIMER_CONFIG_WGM(TC_WGMODE_NORMAL_gc);
+	//enable the overflow interrupt
+	//use the highest priority
+	TIMER_SET_OVERFLOW_INTERRUPT_LEVEL(TC_OVFINTLVL_HI_gc);
+	//enable timer by setting the correct prescaler/clock
+	TIMER_CONFIG_CLOCK_SOURCE(TIMER_CLKSEL_gc);
+	//Restore IRQ
+	IRQ_RESTORE(flags);
+}