File content as of revision 188:3f10722804f9:

/*******************************************************************************
 * Copyright (C) 2016,2018 Maxim Integrated Products, Inc., All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Except as contained in this notice, the name of Maxim Integrated
 * Products, Inc. shall not be used except as stated in the Maxim Integrated
 * Products, Inc. Branding Policy.
 *
 * The mere transfer of this software does not imply any licenses
 * of trade secrets, proprietary technology, copyrights, patents,
 * trademarks, maskwork rights, or any other form of intellectual
 * property whatsoever. Maxim Integrated Products, Inc. retains all
 * ownership rights.
 *******************************************************************************
 */

#include <string.h>
#include "rtc_api.h"
#include "lp_ticker_api.h"
#include "rtc.h"
#include "lp.h"
#include <string.h>

// LOG2 for 32-bit powers of 2
#define LOG2_1(n) (((n) >= (1 <<  1)) ? 1 : 0)
#define LOG2_2(n) (((n) >= (1 <<  2)) ? ( 2 + (LOG2_1((n) >>  2))) : LOG2_1(n))
#define LOG2_4(n) (((n) >= (1 <<  4)) ? ( 4 + (LOG2_2((n) >>  4))) : LOG2_2(n))
#define LOG2_8(n) (((n) >= (1 <<  8)) ? ( 8 + (LOG2_4((n) >>  8))) : LOG2_4(n))
#define LOG2(n)   (((n) >= (1 << 16)) ? (16 + (LOG2_8((n) >> 16))) : LOG2_8(n))

#define LP_TIMER_FREQ_HZ  4096
#define LP_TIMER_PRESCALE RTC_PRESCALE_DIV_2_0
#define LP_TIMER_RATE_HZ  (LP_TIMER_FREQ_HZ >> LP_TIMER_PRESCALE)
#define LP_TIMER_WIDTH    32

static volatile int rtc_inited = 0;
static volatile int lp_ticker_inited = 0;

//******************************************************************************
static void init_rtc(void)
{
    /* Enable power for RTC for all LPx states */
    MXC_PWRSEQ->reg0 |= (MXC_F_PWRSEQ_REG0_PWR_RTCEN_RUN |
                         MXC_F_PWRSEQ_REG0_PWR_RTCEN_SLP);

    /* Enable clock to synchronizers */
    CLKMAN_SetClkScale(CLKMAN_CLK_SYNC, CLKMAN_SCALE_DIV_1);

    /* RTC registers are only reset on a power cycle. Do not reconfigure the RTC
     * if it is already running.
     */
    if (!RTC_IsActive()) {
        rtc_cfg_t cfg;
        memset(&cfg, 0, sizeof(rtc_cfg_t));
        cfg.prescaler = LP_TIMER_PRESCALE;
        cfg.snoozeMode = RTC_SNOOZE_DISABLE;

        int retval = RTC_Init(&cfg);
        MBED_ASSERT(retval == E_NO_ERROR);

        RTC_EnableINT(MXC_F_RTC_FLAGS_OVERFLOW);
        RTC_Start();
    }
}

//******************************************************************************
static void overflow_handler(void)
{
    MXC_RTCTMR->comp[1] += ((UINT32_MAX >> LOG2(LP_TIMER_RATE_HZ)) + 1);
    RTC_ClearFlags(MXC_F_RTC_FLAGS_OVERFLOW);
}

//******************************************************************************
void rtc_init(void)
{
    NVIC_SetVector(RTC3_IRQn, (uint32_t)overflow_handler);
    NVIC_EnableIRQ(RTC3_IRQn);

    // Enable as LP wakeup source
    MXC_PWRSEQ->msk_flags |= MXC_F_PWRSEQ_FLAGS_RTC_ROLLOVER;

    init_rtc();
}

//******************************************************************************
void rtc_free(void)
{
    while (MXC_RTCTMR->ctrl & MXC_F_RTC_CTRL_PENDING);
}

//******************************************************************************
int rtc_isenabled(void)
{
    return !!RTC_IsActive();
}

//******************************************************************************
void rtc_write(time_t t)
{
    MXC_RTCTMR->comp[1] = t - (MXC_RTCTMR->timer >> LOG2(LP_TIMER_RATE_HZ));
    while (MXC_RTCTMR->ctrl & MXC_F_RTC_CTRL_PENDING);
}

//******************************************************************************
time_t rtc_read(void)
{
    return (MXC_RTCTMR->timer >> LOG2(LP_TIMER_RATE_HZ)) + MXC_RTCTMR->comp[1];
}

//******************************************************************************
void lp_ticker_init(void)
{
    RTC_DisableINT(MXC_F_RTC_INTEN_COMP0);
    NVIC_SetVector(RTC0_IRQn, (uint32_t)lp_ticker_irq_handler);
    NVIC_EnableIRQ(RTC0_IRQn);
    init_rtc();
}

//******************************************************************************
void lp_ticker_free(void)
{
    // Disable interrupt associated with LPTICKER API
    RTC_DisableINT(MXC_F_RTC_INTEN_COMP0);

    // RTC hardware is shared by LPTICKER and RTC APIs.
    // Prior initialization of the RTC API gates disabling the RTC hardware.
    if (!(MXC_RTCTMR->inten & MXC_F_RTC_INTEN_OVERFLOW)) {
        RTC_Stop();
    }
}

//******************************************************************************
uint32_t lp_ticker_read(void)
{
    return MXC_RTCTMR->timer;
}

//******************************************************************************
void lp_ticker_set_interrupt(timestamp_t timestamp)
{
    MXC_RTCTMR->comp[0] = timestamp;
    MXC_RTCTMR->flags = MXC_F_RTC_FLAGS_COMP0;
    RTC_EnableINT(MXC_F_RTC_INTEN_COMP0);

    // Enable as LP wakeup source
    MXC_PWRSEQ->msk_flags |= MXC_F_PWRSEQ_FLAGS_RTC_CMPR0;

    // Postponed write pending wait for comp0 and flags
    while (MXC_RTCTMR->ctrl & MXC_F_RTC_CTRL_PENDING);
}

//******************************************************************************
void lp_ticker_disable_interrupt(void)
{
    RTC_DisableINT(MXC_F_RTC_INTEN_COMP0);
}

//******************************************************************************
void lp_ticker_clear_interrupt(void)
{
    RTC_ClearFlags(MXC_F_RTC_FLAGS_COMP0);
}

//******************************************************************************
void lp_ticker_fire_interrupt(void)
{
    NVIC_SetPendingIRQ(RTC0_IRQn);
}

//******************************************************************************
const ticker_info_t *lp_ticker_get_info(void)
{
    static const ticker_info_t info = {
        LP_TIMER_RATE_HZ,
        LP_TIMER_WIDTH
    };

    return &info;
}