nes-proj/drivers/cpu/arm/aducrf101/Common/system_ADuCRF101.c

/**
 * Copyright (c) 2014, Analog Devices, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted (subject to the limitations in the
 * disclaimer below) provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the
 *   distribution.
 *
 * - Neither the name of Analog Devices, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE
 * GRANTED BY THIS LICENSE.  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT
 * HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/**
@file     system_ADuCRF101.c
@brief    CMSIS Cortex-M3 Device Peripheral Access Layer Implementation File
          for the ADuCRF101
@version  v1.0
@author   PAD CSE group, Analog Devices Inc
@date     January 14th 2013
**/

#include <stdint.h>
#include "ADuCRF101.h"


/*----------------------------------------------------------------------------
  DEFINES
 *---------------------------------------------------------------------------*/

/* Extract the Clock Divider */
#define __CCLK_DIV (1 << (pADI_CLKCTL->CLKCON & CLKCON_CD_MSK) )

/* define the clock multiplexer input frequencies */
#define __HFOSC    16000000
#define __LFXTAL      32768
#define __LFOSC       32768

/*----------------------------------------------------------------------------
  Internal Clock Variables
 *---------------------------------------------------------------------------*/
static uint32_t uClk = 0;    /* Undivided System Clock Frequency (UCLK)   */
static uint32_t uClkDiv = 0; /* Divided System Clock Frequency (UCLK_DIV) */

/* Frequency of the external clock source connected to P0.5 */
static uint32_t SystemExtClock = 0;

/*----------------------------------------------------------------------------
  Clock functions
 *---------------------------------------------------------------------------*/
void SystemCoreClockUpdate (void)            /* Get Core Clock Frequency     */
{
/* pre-processor verification that clock mux mask and allowed values agree   */
#if ((CLKCON_CLKMUX_HFOSC   \
    | CLKCON_CLKMUX_LFXTAL  \
    | CLKCON_CLKMUX_LFOSC   \
    | CLKCON_CLKMUX_EXTP05) \
    == CLKCON_CLKMUX_MSK)

    /* update the system core clock according the the current clock mux setting */
    switch (pADI_CLKCTL->CLKCON & CLKCON_CLKMUX_MSK ) {

        case CLKCON_CLKMUX_HFOSC:
            uClk = __HFOSC;
            break;
        case CLKCON_CLKMUX_LFXTAL:
            uClk = __LFXTAL;
            break;
        case CLKCON_CLKMUX_LFOSC:
            uClk = __LFOSC;
            break;
        case CLKCON_CLKMUX_ECLKIN:
            uClk = SystemExtClock;
            break;
        /* no need to catch default case due to pre-processor test */
    }

    /* update the divided system clock */
    uClkDiv = uClk / __CCLK_DIV;

#else
#error "Clock mux mask and allowed value mismatch!"
#endif
}

/**
 * Initialize the system
 *
 * @return none
 *
 * @brief  Setup the microcontroller system.
 *         Initialize the System and update the SystemFrequency variable.
 */
void SystemInit (void)
{
   /* reset CLKCON register */
   pADI_CLKCTL->CLKCON = CLKCON_RVAL;

   /* reset XOSCCON register */
   pADI_CLKCTL->XOSCCON = XOSCCON_RVAL;

   /* compute internal clocks */
   SystemCoreClockUpdate();
}

/**
 * @brief  Sets the system external clock frequency
 *
 * @param  ExtClkFreq   External clock frequency in Hz
 * @return none
 *
 * Sets the clock frequency of the source connected to P0.5 clock input source
 */
void SetSystemExtClkFreq (uint32_t ExtClkFreq)
{
    SystemExtClock = ExtClkFreq;
}

/**
 * @brief  Gets the system external clock frequency
 *
 * @return External Clock frequency
 *
 * Gets the clock frequency of the source connected to P0.5 clock input source
 */
uint32_t GetSystemExtClkFreq (void)
{
    return  SystemExtClock;
}


/* set the system clock dividers */
void SystemSetClockDivider(uint16_t div)
{
    /* critical region */
    __disable_irq();

    /* read-modify-write without any interrupts */

    pADI_CLKCTL->CLKCON &= ~(CLKCON_CD_MSK);   /* keep everything else */
    pADI_CLKCTL->CLKCON |= div;  /* set new value */

    /* end critical region */
    __enable_irq();

    /* refresh internal clock variables */
    SystemCoreClockUpdate();
}


uint32_t SystemGetClockFrequency(void)
{
    return uClkDiv;
}