mbed-os/targets/TARGET_Ambiq_Micro/TARGET_Apollo3/device/us_ticker.c

/*
 * Copyright (c) 2020 SparkFun Electronics
 * SPDX-License-Identifier: MIT
 *
 * 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 THE
 * AUTHORS OR COPYRIGHT HOLDERS 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.
 */

#include "us_ticker_api.h"
#include <stdio.h>
/**
 * \defgroup hal_us_ticker Microsecond Ticker
 * Low level interface to the microsecond ticker of a target
 *
 * # Defined behavior
 * * Has a reported frequency between 250KHz and 8MHz for counters which are less than 32 bits wide - Verified by test ::us_ticker_info_test
 * * Has a reported frequency up to 100MHz for counters which are 32 bits wide - Verified by test ::us_ticker_info_test
 * * Has a counter that is at least 16 bits wide - Verified by test ::us_ticker_info_test
 * * All behavior defined by the @ref hal_ticker_shared "ticker specification"
 *
 * # Undefined behavior
 * * See the @ref hal_ticker_shared "ticker specification"
 *
 * @see hal_us_ticker_tests
 *
 * # Compile-time optimization macros
 *

 * @{
 */

/**
 * \defgroup hal_us_ticker_tests Microsecond Ticker tests
 * Tests to validate the proper implementation of the microsecond ticker
 *
 * To run the microsecond ticker hal tests use the command:
 *
 *     mbed test -t <toolchain> -m <target> -n tests-mbed_hal-common_ticker*,tests-mbed_hal-us_ticker*
 *
 * @see hal_ticker_tests
 *
 */
/* HAL us ticker */

static bool us_ticker_initialized = false;

/** Initialize the ticker
 *
 * Initialize or re-initialize the ticker. This resets all the
 * clocking and prescaler registers, along with disabling
 * the compare interrupt.
 *
 * @note Initialization properties tested by ::ticker_init_test
 *
 */
void us_ticker_init(void)
{
    if (us_ticker_initialized) {
        am_hal_stimer_int_disable(US_TICKER_STIMER_INT_COMPARE);
        return;
    }

    NVIC_SetVector(STIMER_CMPR0_IRQn, (uint32_t)us_ticker_irq_handler);
    NVIC_EnableIRQ(STIMER_CMPR0_IRQn);
    am_hal_stimer_config(AM_HAL_STIMER_CFG_CLEAR | AM_HAL_STIMER_CFG_FREEZE);
    am_hal_stimer_config(US_TICKER_FREQ);
    us_ticker_initialized = true;
}

/** Deinitialize the us ticker
 *
 * Powerdown the us ticker in preparation for sleep, powerdown, or reset.
 *
 * After this function is called, no other ticker functions should be called
 * except us_ticker_init(), calling any function other than init is undefined.
 *
 * @note This function stops the ticker from counting.
 *
 */
void us_ticker_free(void)
{
    am_hal_stimer_config(AM_HAL_STIMER_CFG_FREEZE);
    am_hal_stimer_int_disable(US_TICKER_STIMER_INT_COMPARE);
    us_ticker_initialized = false;
}

/** Read the current counter
 *
 * Read the current counter value without performing frequency conversions.
 * If no rollover has occurred, the seconds passed since us_ticker_init()
 * was called can be found by dividing the ticks returned by this function
 * by the frequency returned by ::us_ticker_get_info.
 *
 * @return The current timer's counter value in ticks
 *
 */
uint32_t us_ticker_read(void)
{
    return am_hal_stimer_counter_get();
}

/** Set interrupt for specified timestamp
 *
 * @param timestamp The time in ticks to be set
 *
 * @note no special handling needs to be done for times in the past
 * as the common timer code will detect this and call
 * us_ticker_fire_interrupt() if this is the case
 *
 * @note calling this function with timestamp of more than the supported
 * number of bits returned by ::us_ticker_get_info results in undefined
 * behavior.
 *
 */
void us_ticker_set_interrupt(timestamp_t timestamp)
{

    uint32_t instance = 0;
    switch (US_TICKER_STIMER_INT_COMPARE) {
        default:
        case AM_HAL_STIMER_INT_COMPAREA:
            instance = 0;
            break;
        case AM_HAL_STIMER_INT_COMPAREB:
            instance = 1;
            break;
        case AM_HAL_STIMER_INT_COMPAREC:
            instance = 2;
            break;
        case AM_HAL_STIMER_INT_COMPARED:
            instance = 3;
            break;
        case AM_HAL_STIMER_INT_COMPAREE:
            instance = 4;
            break;
        case AM_HAL_STIMER_INT_COMPAREF:
            instance = 5;
            break;
        case AM_HAL_STIMER_INT_COMPAREG:
            instance = 6;
            break;
        case AM_HAL_STIMER_INT_COMPAREH:
            instance = 7;
            break;
    }

    am_hal_stimer_int_enable(US_TICKER_STIMER_INT_COMPARE);
    timestamp_t now = (timestamp_t)am_hal_stimer_counter_get();
    am_hal_stimer_compare_delta_set(instance, (timestamp - now));
    CTIMER->STCFG |= (AM_HAL_STIMER_CFG_COMPARE_A_ENABLE << instance);
}

/** Disable us ticker interrupt
 *
 */
void us_ticker_disable_interrupt(void)
{
    am_hal_stimer_int_disable(US_TICKER_STIMER_INT_COMPARE);
}

/** Clear us ticker interrupt
 *
 */
void us_ticker_clear_interrupt(void)
{
    am_hal_stimer_int_clear(US_TICKER_STIMER_INT_COMPARE);
}

/** Set pending interrupt that should be fired right away.
 *
 * The ticker should be initialized prior calling this function.
 *
 */
void us_ticker_fire_interrupt(void)
{
    am_hal_stimer_int_enable(US_TICKER_STIMER_INT_COMPARE);
    am_hal_stimer_int_set(US_TICKER_STIMER_INT_COMPARE);
}

/** Get frequency and counter bits of this ticker.*/
const ticker_info_t *us_ticker_get_info(void)
{
    static const ticker_info_t info = {
        3000000, // 3 MHz
        32       // 32 bit counter
    };
    return &info;
}