rt-thread/bsp/imx6sx/cortex-a9/drivers/board.c

/*
 * File      : board.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2012, RT-Thread Development Team
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rt-thread.org/license/LICENSE
 *
 * Change Logs:
 * Date           Author       Notes
 * 2012-11-20     Bernard    the first version
 */

#include <rthw.h>
#include <rtthread.h>

#include "board.h"

#include <registers/regsarmglobaltimer.h>
#include <registers/regsepit.h>

#include <uart/imx_uart.h>
#include <timer/epit.h>
#include <core/cortex_a9.h>

static void rt_hw_timer_isr(int vector, void *param)
{
    rt_tick_increase();
    epit_get_compare_event(HW_EPIT1);
}

int rt_hw_timer_init(void)
{
    uint32_t freq;
    // The ARM private peripheral clock is half the CPU clock.
    uint32_t periphClock = get_main_clock(CPU_CLK) / 2;
    uint32_t prescaler = (periphClock / 1000000) - 1;

    // Divide down the prescaler until it fits into 8 bits. We add up the number of ticks
    // it takes to equal a microsecond interval.
    while (prescaler > 0xff)
    {
        prescaler /= 2;
    }

    // Make sure the timer is off.
    HW_ARMGLOBALTIMER_CONTROL.B.TIMER_ENABLE = 0;

    // Clear counter.
    HW_ARMGLOBALTIMER_COUNTERn_WR(0, 0);
    HW_ARMGLOBALTIMER_COUNTERn_WR(1, 0);

    // Set prescaler and clear other flags.
    HW_ARMGLOBALTIMER_CONTROL_WR(BF_ARMGLOBALTIMER_CONTROL_PRESCALER(prescaler));

    // Now turn on the timer.
    HW_ARMGLOBALTIMER_CONTROL.B.TIMER_ENABLE = 1;

    freq = get_main_clock(IPG_CLK);
    epit_init(HW_EPIT1, CLKSRC_IPG_CLK, freq / 1000000,
              SET_AND_FORGET, 10000, WAIT_MODE_EN | STOP_MODE_EN);

    epit_counter_enable(HW_EPIT1, 10000, IRQ_MODE);

    rt_hw_interrupt_install(IMX_INT_EPIT1, rt_hw_timer_isr, RT_NULL, "tick");
    rt_hw_interrupt_umask(IMX_INT_EPIT1);

    return 0;
}
INIT_BOARD_EXPORT(rt_hw_timer_init);

/**
 * This function will initialize beaglebone board
 */
void rt_hw_board_init(void)
{
    enable_neon_fpu();
    disable_strict_align_check();

    rt_components_board_init();
    rt_console_set_device(RT_CONSOLE_DEVICE_NAME);
}

/*@}*/