arch/nrf53: add tickless support
This commit is contained in:
raiden00pl
Alan Carvalho de Assis
parent
f9f41bbd95
commit
d23759d457
3 changed files with 368 additions and 0 deletions
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@ -248,8 +248,29 @@ config NRF53_SYSTIMER_SYSTICK
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you choose this option, WFE/WFI will not be used
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in idle loop.
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config NRF53_SYSTIMER_RTC
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bool "RTC"
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select NRF53_RTC
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select SCHED_TICKLESS
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select SCHED_TICKLESS_ALARM
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select NRF53_USE_LFCLK
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---help---
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Use RTC timer in tickless mode.
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endchoice
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if NRF53_SYSTIMER_RTC
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config NRF53_SYSTIMER_RTC_INSTANCE
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int "RTC timer instance"
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default 0 if !NRF53_SOFTDEVICE_CONTROLLER
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default 1 if NRF53_SOFTDEVICE_CONTROLLER
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range 0 1
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---help---
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Which RTC instance to use to drive the system timer
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endif
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endmenu # System Timer
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menu "PWM configuration"
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@ -22,7 +22,12 @@ include armv8-m/Make.defs
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ifeq ($(CONFIG_NRF53_SYSTIMER_SYSTICK),y)
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CHIP_CSRCS += nrf53_systick.c
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else
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ifeq ($(CONFIG_NRF53_SYSTIMER_RTC),y)
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CHIP_CSRCS += nrf53_tickless_rtc.c
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endif
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endif
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CHIP_CSRCS += nrf53_start.c nrf53_clockconfig.c nrf53_irq.c nrf53_utils.c
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CHIP_CSRCS += nrf53_allocateheap.c nrf53_lowputc.c nrf53_gpio.c
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CHIP_CSRCS += nrf53_uid.c
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342
arch/arm/src/nrf53/nrf53_tickless_rtc.c
Normal file
342
arch/arm/src/nrf53/nrf53_tickless_rtc.c
Normal file
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@ -0,0 +1,342 @@
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/****************************************************************************
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* arch/arm/src/nrf53/nrf53_tickless_rtc.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdbool.h>
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/arch.h>
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#include "arm_internal.h"
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#include "hardware/nrf53_rtc.h"
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#include "nrf53_rtc.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Check configuration */
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#ifdef CONFIG_TIMER_ARCH
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# error CONFIG_TIMER_ARCH must be not set
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#endif
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/* Check corresponding RTC support */
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#if (CONFIG_NRF53_SYSTIMER_RTC_INSTANCE == 0) && !defined(CONFIG_NRF53_RTC0)
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# error "Support for RTC0 is not enabled"
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#elif (CONFIG_NRF53_SYSTIMER_RTC_INSTANCE == 1) && !defined(CONFIG_NRF53_RTC1)
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# error "Support for RTC1 is not enabled"
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#endif
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#define NRF53_RTC_PERIOD (512)
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#define NRF53_RTC_MAX (0x00ffffff)
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#define NRF53_RTC_MAX_TIME (NRF53_RTC_MAX * 31)
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/* Convert uS to timer count for f = 32768Hz, using more precision
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* when possible:
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* (1 / 32768) s ~ 30.51 uS ~ 31 uS
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* 512 * (1 / 32768) s = 0.015625 s = 15625 uS
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* So, instead of always dividing by 31, if t * 512 < (2**32 - 1), we can do:
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* (t * 512) / 15625 ~ t / 30.51
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*/
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#define USEC_TO_COUNTER(t) (t > 0x7fffff ? (t / 31) : ((t * 512) / 15625))
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/* To convert from counter to uS we split the counter into one second worth
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* of counts (32768) and a fractional part we can safely multiply first
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* by (USEC_PER_SEC/8) and still be within 32 bit value
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*/
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#define COUNTER_TO_USEC(c) ((c / 32768) * USEC_PER_SEC) + \
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(((c % 32768) * (USEC_PER_SEC / 8)) / (32768 / 8))
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/****************************************************************************
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* Private Types
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****************************************************************************/
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struct nrf53_tickless_dev_s
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{
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struct nrf53_rtc_dev_s *rtc; /* nrf53 RTC driver */
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uint32_t periods; /* how many times the timer overflowed */
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bool alarm_set; /* is the alarm set? */
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struct timespec alarm; /* absolute time of alarm */
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static int rtc_handler(int irq, void *context, void *arg);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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struct nrf53_tickless_dev_s g_tickless_dev;
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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static inline void rtc_counter_to_ts(uint32_t counter, struct timespec *now)
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{
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uint32_t usec;
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usec = COUNTER_TO_USEC(counter);
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now->tv_sec = usec / USEC_PER_SEC;
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now->tv_nsec = (usec % USEC_PER_SEC) * NSEC_PER_USEC;
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now->tv_sec += g_tickless_dev.periods * NRF53_RTC_PERIOD;
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}
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static void rtc_prepare_alarm(void)
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{
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struct timespec now;
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struct timespec delta;
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uint32_t usec;
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uint32_t counter;
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uint32_t target_counter;
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const uint32_t rtc_base = NRF53_RTC_GETBASE(g_tickless_dev.rtc);
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/* Get current absolute time */
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counter = NRF53_RTC_GETCOUNTER_REG(rtc_base);
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rtc_counter_to_ts(counter, &now);
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/* Obtain relative time to alarm */
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clock_timespec_subtract(&g_tickless_dev.alarm, &now, &delta);
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usec = delta.tv_sec * USEC_PER_SEC + delta.tv_nsec / NSEC_PER_USEC;
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/* Check if the alarm is to expire within one RTC period, if so we can set
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* the CC.
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*/
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if (usec < NRF53_RTC_PERIOD * USEC_PER_SEC)
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{
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/* Obtain absolute number of microseconds of alarm within current
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* RTC period.
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*/
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usec = (g_tickless_dev.alarm.tv_sec % NRF53_RTC_PERIOD) *
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USEC_PER_SEC + g_tickless_dev.alarm.tv_nsec / NSEC_PER_USEC;
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/* Compute counter value for that point in time */
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target_counter = USEC_TO_COUNTER(usec);
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/* Enable interrupt. First set CC to distant value to ensure
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* no match will be generated. Doing things this way we now that
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* once we write a CC value it should be ready to match.
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*/
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NRF53_RTC_SETCC_REG(rtc_base, 0, counter - 1);
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NRF53_RTC_ENABLEINT(g_tickless_dev.rtc, NRF53_RTC_EVT_COMPARE0);
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/* Set CC to desired value */
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NRF53_RTC_SETCC_REG(rtc_base, 0, target_counter);
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/* Ensure counter fires: from nrf53832_PS_v1.4 (p. 245) we know that
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* "If the COUNTER is N, writing N+2 to a CC register is
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* guaranteed to trigger a COMPARE event at N+2.", so anything
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* less than that is not guaranteed and it may not ever match.
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*
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* To ensure this, we check if CC < N + 2, and if so we set CC = N+2.
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* We repeat this until this is satisfied (as the counter may change
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* in between calculations).
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*/
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while (NRF53_RTC_GETCC_REG(rtc_base, 0) <
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NRF53_RTC_GETCOUNTER_REG(rtc_base) + 2)
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{
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NRF53_RTC_SETCC_REG(rtc_base, 0,
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NRF53_RTC_GETCOUNTER_REG(rtc_base) + 2);
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}
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}
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}
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/****************************************************************************
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* Name: rtc_handler
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****************************************************************************/
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static int rtc_handler(int irq, void *context, void *arg)
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{
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irqstate_t flags;
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flags = enter_critical_section();
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/* if the timer wrapped-around */
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if (NRF53_RTC_CHECKINT(g_tickless_dev.rtc, NRF53_RTC_EVT_OVRFLW))
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{
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/* ack interrupt */
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NRF53_RTC_ACKINT(g_tickless_dev.rtc, NRF53_RTC_EVT_OVRFLW);
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/* count one more period */
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g_tickless_dev.periods++;
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/* check if the currently set alarm is to fire in this new period */
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if (g_tickless_dev.alarm_set)
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{
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rtc_prepare_alarm();
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}
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}
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/* if the compare event fired */
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if (NRF53_RTC_CHECKINT(g_tickless_dev.rtc, NRF53_RTC_EVT_COMPARE0))
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{
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struct timespec now;
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/* cancel alarm and get current time */
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up_alarm_cancel(&now);
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/* let scheduler now of alarm firing */
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nxsched_alarm_expiration(&now);
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}
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leave_critical_section(flags);
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return OK;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: up_alarm_cancel
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****************************************************************************/
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int up_alarm_cancel(struct timespec *ts)
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{
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uint32_t counter;
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irqstate_t flags;
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flags = enter_critical_section();
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NRF53_RTC_DISABLEINT(g_tickless_dev.rtc, NRF53_RTC_EVT_COMPARE0);
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NRF53_RTC_GETCOUNTER(g_tickless_dev.rtc, &counter);
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rtc_counter_to_ts(counter, ts);
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NRF53_RTC_ACKINT(g_tickless_dev.rtc, NRF53_RTC_EVT_COMPARE0);
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g_tickless_dev.alarm_set = false;
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leave_critical_section(flags);
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return OK;
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}
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/****************************************************************************
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* Name: up_alarm_start
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****************************************************************************/
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int up_alarm_start(const struct timespec *ts)
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{
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irqstate_t flags;
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flags = enter_critical_section();
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/* remember the alarm time */
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g_tickless_dev.alarm_set = true;
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g_tickless_dev.alarm = *ts;
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rtc_prepare_alarm();
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leave_critical_section(flags);
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return OK;
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}
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/****************************************************************************
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* Name: up_timer_gettime
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****************************************************************************/
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int up_timer_gettime(struct timespec *ts)
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{
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uint32_t counter;
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irqstate_t flags;
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flags = enter_critical_section();
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NRF53_RTC_GETCOUNTER(g_tickless_dev.rtc, &counter);
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rtc_counter_to_ts(counter, ts);
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leave_critical_section(flags);
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return OK;
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}
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/****************************************************************************
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* Name: up_timer_initialize
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****************************************************************************/
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void up_timer_initialize(void)
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{
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struct timespec ts;
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memset(&g_tickless_dev, 0, sizeof(struct nrf53_tickless_dev_s));
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g_tickless_dev.rtc = nrf53_rtc_init(CONFIG_NRF53_SYSTIMER_RTC_INSTANCE);
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/* Ensure we have support for the selected RTC instance */
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ASSERT(g_tickless_dev.rtc);
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/* Configure prescaler */
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NRF53_RTC_SETPRE(g_tickless_dev.rtc, 0);
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/* Configure ISR */
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NRF53_RTC_SETISR(g_tickless_dev.rtc, rtc_handler, NULL);
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/* Enable overflow interrupt */
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NRF53_RTC_ENABLEINT(g_tickless_dev.rtc, NRF53_RTC_EVT_OVRFLW);
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/* Start counting */
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NRF53_RTC_CLEAR(g_tickless_dev.rtc);
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NRF53_RTC_ACKINT(g_tickless_dev.rtc, NRF53_RTC_EVT_OVRFLW);
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NRF53_RTC_ACKINT(g_tickless_dev.rtc, NRF53_RTC_EVT_COMPARE0);
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NRF53_RTC_START(g_tickless_dev.rtc);
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/* kick off alarm scheduling */
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ts.tv_sec = ts.tv_nsec = 0;
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nxsched_alarm_expiration(&ts);
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}
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