source: rtems/bsps/arm/atsam/start/power-rtc.c @ 522cde4

/*
 * Copyright (c) 2016 embedded brains GmbH.  All rights reserved.
 *
 *  embedded brains GmbH
 *  Dornierstr. 4
 *  82178 Puchheim
 *  Germany
 *  <rtems@embedded-brains.de>
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rtems.org/license/LICENSE.
 */

#include <bsp.h>
#include <bsp/power.h>
#include <bsp/irq.h>

#include <libchip/chip.h>

#define ATSAM_ENABLE_ALARM_INTERRUPT RTC_IER_ALREN

static void set_rtc_alarm_interrupt(uint32_t interval)
{
        Rtc *rtc = RTC;
        uint8_t hour;
        uint8_t minute;
        uint8_t second;
        uint32_t time;

        /* Clear current status register */
        RTC_ClearSCCR(rtc, 0x3F);

        RTC_GetTime(rtc, &hour, &minute, &second);

        time = UINT32_C(3600) * hour + UINT32_C(60) * minute + second;
        time = (time + interval) % (UINT32_C(24) * 3600);

        second = (uint8_t) (time % 60);
        minute = (uint8_t) ((time / 60) % 60);
        hour = (uint8_t) (time / 3600);

        if (interval < 60) {
                RTC_SetTimeAlarm(rtc, NULL, NULL, &second);
        } else if (interval < 3600) {
                RTC_SetTimeAlarm(rtc, NULL, &minute, &second);
        } else {
                RTC_SetTimeAlarm(rtc, &hour, &minute, &second);
        }

        RTC_EnableIt(rtc, ATSAM_ENABLE_ALARM_INTERRUPT);
}

static void rtc_interrupt_handler(void *arg)
{
        atsam_power_data_rtc_driver *rtc_data;

        rtc_data = (atsam_power_data_rtc_driver *)arg;
        set_rtc_alarm_interrupt(rtc_data->interval);
}

static void rtc_alarm_handler(void *arg)
{
        Rtc *rtc = RTC;
        rtems_status_code sc;

        /* Clear current status register */
        RTC_ClearSCCR(rtc, 0x3F);

        /* Switch off all RTC interrupts */
        RTC_DisableIt(rtc, 0x1F);

        /* Install RTC interrupt handler */
        sc = rtems_interrupt_handler_install(RTC_IRQn,
            "RTC",
            RTEMS_INTERRUPT_UNIQUE,
            rtc_interrupt_handler,
            arg
        );
        assert(sc == RTEMS_SUCCESSFUL);
}

static void set_time(void)
{
        rtems_time_of_day tod;
        rtems_status_code sc;

        atsam_rtc_get_time(&tod);
        sc = rtems_clock_set(&tod);
        assert(sc == RTEMS_SUCCESSFUL);
}

void atsam_power_handler_rtc_driver(
    const atsam_power_control *control,
    atsam_power_state state
)
{
        atsam_power_data_rtc_driver *rtc_data;
        rtems_interrupt_level level;
        Rtc *rtc = RTC;

        rtc_data = (atsam_power_data_rtc_driver *)control->data.arg;

        switch (state) {
                case ATSAM_POWER_ON:
                        RTC_DisableIt(rtc, ATSAM_ENABLE_ALARM_INTERRUPT);
                        set_time();
                        break;
                case ATSAM_POWER_OFF:
                        set_rtc_alarm_interrupt(rtc_data->interval);
                        break;
                case ATSAM_POWER_INIT:
                        /* Enable fast startup via RTC alarm */
                        rtems_interrupt_disable(level);
                        PMC->PMC_FSMR |= PMC_FSMR_RTCAL;
                        rtems_interrupt_enable(level);

                        rtc_alarm_handler(rtc_data);
                        break;
                default:
                        break;
        }
}