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116 lines
2.8 KiB
C
116 lines
2.8 KiB
C
/*
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* Copyright (C) 2020 Kaspar Schleiser <kaspar@schleiser.de>
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* 2020 Freie Universität Berlin
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* 2020 Inria
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*
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* This file is subject to the terms and conditions of the GNU Lesser General
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* Public License v2.1. See the file LICENSE in the top level directory for more
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* details.
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*/
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/**
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* @ingroup sys_ztimer_periph_rtt
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* @{
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*
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* @file
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* @brief ztimer periph/rtt implementation
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*
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* @author Kaspar Schleiser <kaspar@schleiser.de>
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*
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* @}
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*/
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#include "assert.h"
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#include "irq.h"
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#include "periph/rtt.h"
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#include "ztimer/periph_rtt.h"
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#define ENABLE_DEBUG 0
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#include "debug.h"
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static void _ztimer_periph_rtt_callback(void *arg)
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{
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ztimer_handler((ztimer_clock_t *)arg);
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}
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static void _ztimer_periph_rtt_set(ztimer_clock_t *clock, uint32_t val)
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{
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if (val < RTT_MIN_OFFSET) {
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/* the rtt might advance right between the call to rtt_get_counter()
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* and rtt_set_alarm(). If that happens with val==1, we'd set an alarm
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* to the current time, which would then underflow. To avoid this, we
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* set the alarm at least two ticks in the future. TODO: confirm this
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* is sufficient, or conceive logic to lower this value.
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*
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* @note RTT_MIN_OFFSET defaults to 2, but some platforms might have
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* different values.
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*/
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val = RTT_MIN_OFFSET;
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}
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unsigned state = irq_disable();
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/* ensure RTT_MAX_VALUE is (2^n - 1) */
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static_assert((RTT_MAX_VALUE == UINT32_MAX) ||
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!((RTT_MAX_VALUE + 1) & (RTT_MAX_VALUE)),
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"RTT_MAX_VALUE needs to be (2^n) - 1");
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rtt_set_alarm(
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(rtt_get_counter() + val) & RTT_MAX_VALUE, _ztimer_periph_rtt_callback,
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clock);
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irq_restore(state);
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}
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static uint32_t _ztimer_periph_rtt_now(ztimer_clock_t *clock)
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{
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(void)clock;
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return rtt_get_counter();
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}
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static void _ztimer_periph_rtt_cancel(ztimer_clock_t *clock)
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{
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(void)clock;
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rtt_clear_alarm();
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}
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#if MODULE_ZTIMER_ONDEMAND_RTT
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static void _ztimer_periph_rtt_start(ztimer_clock_t *clock)
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{
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(void)clock;
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rtt_poweron();
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}
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static void _ztimer_periph_rtt_stop(ztimer_clock_t *clock)
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{
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(void)clock;
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rtt_poweroff();
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}
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#endif /* MODULE_ZTIMER_ONDEMAND_RTT */
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static const ztimer_ops_t _ztimer_periph_rtt_ops = {
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.set = _ztimer_periph_rtt_set,
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.now = _ztimer_periph_rtt_now,
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.cancel = _ztimer_periph_rtt_cancel,
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#if MODULE_ZTIMER_ONDEMAND_RTT
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.start = _ztimer_periph_rtt_start,
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.stop = _ztimer_periph_rtt_stop,
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#endif
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};
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void ztimer_periph_rtt_init(ztimer_periph_rtt_t *clock)
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{
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clock->ops = &_ztimer_periph_rtt_ops;
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clock->max_value = RTT_MAX_VALUE;
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rtt_init();
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#if MODULE_ZTIMER_ONDEMAND_RTT
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rtt_poweroff();
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#else
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rtt_poweron();
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#endif
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#if !MODULE_ZTIMER_ONDEMAND
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ztimer_init_extend(clock);
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#endif
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}
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