system_n32g45x.c

/*****************************************************************************
 * Copyright (c) 2019, Nations Technologies Inc.
 *
 * All rights reserved.
 * ****************************************************************************
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the disclaimer below.
 *
 * Nations' name may not be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY NATIONS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
 * DISCLAIMED. IN NO EVENT SHALL NATIONS 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_n32g45x.c
 * @author Nations
 * @version v1.0.1
 *
 * @copyright Copyright (c) 2019, Nations Technologies Inc. All rights reserved.
 */
#include "n32g45x.h"

/* Uncomment the line corresponding to the desired System clock (SYSCLK)
   frequency (after reset the HSI is used as SYSCLK source)

   IMPORTANT NOTE:
   ==============
   1. After each device reset the HSI is used as System clock source.

   2. Please make sure that the selected System clock doesn't exceed your
   device's maximum frequency.

   3. If none of the define below is enabled, the HSI is used as System clock
    source.

   4. The System clock configuration functions provided within this file assume
   that:
        - For Low, Medium and High density Value line devices an external 8MHz
          crystal is used to drive the System clock.
        - For Low, Medium and High density devices an external 8MHz crystal is
          used to drive the System clock.
        - For Connectivity line devices an external 25MHz crystal is used to
   drive the System clock. If you are using different crystal you have to adapt
   those functions accordingly.
    */

#define SYSCLK_USE_HSI     0
#define SYSCLK_USE_HSE     1
#define SYSCLK_USE_HSI_PLL 2
#define SYSCLK_USE_HSE_PLL 3

#ifndef SYSCLK_FREQ
#define SYSCLK_FREQ 144000000
#endif

#ifndef SYSCLK_SRC
#define SYSCLK_SRC SYSCLK_USE_HSE_PLL
#endif

#if SYSCLK_SRC == SYSCLK_USE_HSI

#if SYSCLK_FREQ != HSI_VALUE
#error SYSCL_FREQ must be set to HSI_VALUE
#endif

#elif SYSCLK_SRC == SYSCLK_USE_HSE

#ifndef HSE_VALUE
#error HSE_VALUE must be defined!
#endif

#if SYSCLK_FREQ != HSE_VALUE
#error SYSCL_FREQ must be set to HSE_VALUE
#endif

#elif SYSCLK_SRC == SYSCLK_USE_HSI_PLL

#if (SYSCLK_FREQ % (HSI_VALUE / 2) == 0) && (SYSCLK_FREQ / (HSI_VALUE / 2) >= 2)                                       \
    && (SYSCLK_FREQ / (HSI_VALUE / 2) <= 32)

#define PLLSRC_DIV 2
#define PLL_MUL    (SYSCLK_FREQ / (HSI_VALUE / 2))

#else
#error Cannot make a PLL multiply factor to SYSCLK_FREQ.
#endif

#elif SYSCLK_SRC == SYSCLK_USE_HSE_PLL

#ifndef HSE_VALUE
#error HSE_VALUE must be defined!
#endif

#if ((SYSCLK_FREQ % (HSE_VALUE / 2)) == 0) && (SYSCLK_FREQ / (HSE_VALUE / 2) >= 2)                                     \
    && (SYSCLK_FREQ / (HSE_VALUE / 2) <= 32)

#define PLLSRC_DIV 2
#define PLL_MUL    (SYSCLK_FREQ / (HSE_VALUE / 2))

#elif (SYSCLK_FREQ % HSE_VALUE == 0) && (SYSCLK_FREQ / HSE_VALUE >= 2) && (SYSCLK_FREQ / HSE_VALUE <= 32)

#define PLLSRC_DIV 1
#define PLL_MUL    (SYSCLK_FREQ / HSE_VALUE)

#else
#error Cannot make a PLL multiply factor to SYSCLK_FREQ.
#endif

#else
#error wrong value for SYSCLK_SRC
#endif

/* #define VECT_TAB_SRAM */
#define VECT_TAB_OFFSET 0x0 /*!< Vector Table base offset field. This value must be a multiple of 0x200. */

/*******************************************************************************
 *  Clock Definitions
 *******************************************************************************/
uint32_t SystemCoreClock = SYSCLK_FREQ; /*!< System Clock Frequency (Core Clock) */

const uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};

static void SetSysClock(void);

#ifdef DATA_IN_ExtSRAM
static void SystemInit_ExtMemCtl(void);
#endif /* DATA_IN_ExtSRAM */

/**
 * @brief  Setup the microcontroller system
 *         Initialize the Embedded Flash Interface, the PLL and update the
 *         SystemCoreClock variable.
 * @note   This function should be used only after reset.
 */
void SystemInit(void)
{
    /* FPU settings
     * ------------------------------------------------------------*/
#if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
    SCB->CPACR |= ((3UL << 10 * 2) | (3UL << 11 * 2)); /* set CP10 and CP11 Full Access */
#endif

    /* Reset the RCC clock configuration to the default reset state(for debug purpose) */
    /* Set HSIEN bit */
    RCC->CTRL |= (uint32_t)0x00000001;

    /* Reset SW, HPRE, PPRE1, PPRE2, ADCPRE and MCO bits */
    RCC->CFG &= (uint32_t)0xF8FFC000;

    /* Reset HSEON, CLKSSEN and PLLEN bits */
    RCC->CTRL &= (uint32_t)0xFEF6FFFF;

    /* Reset HSEBYP bit */
    RCC->CTRL &= (uint32_t)0xFFFBFFFF;

    /* Reset PLLSRC, PLLXTPRE, PLLMUL and USBPRES/OTGFSPRE bits */
    RCC->CFG &= (uint32_t)0xF700FFFF;

    /* Reset CFG2 register */
    RCC->CFG2 = 0x00000000;

    /* Reset CFG3 register */
    RCC->CFG3 = 0x00000000;

    /* Disable all interrupts and clear pending bits  */
    RCC->CLKINT = 0x009F0000;

    /* Enable ex mode */
    RCC->APB1PCLKEN |= RCC_APB1PCLKEN_PWREN;
    PWR->CTRL3 |= 0x00000001;
    RCC->APB1PCLKEN &= (uint32_t)(~RCC_APB1PCLKEN_PWREN);

    /* Enable ICACHE and Prefetch Buffer */
     FLASH->AC |= (uint32_t)(FLASH_AC_ICAHEN | FLASH_AC_PRFTBFEN);

#ifdef DATA_IN_ExtSRAM
    SystemInit_ExtMemCtl();
#endif /* DATA_IN_ExtSRAM */

    /* Configure the System clock frequency, HCLK, PCLK2 and PCLK1 prescalers */
    /* Configure the Flash Latency cycles and enable prefetch buffer */
    SetSysClock();

#ifdef VECT_TAB_SRAM
    SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM. */
#else
    SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH. */
#endif
}

/**
 * @brief  Update SystemCoreClock variable according to Clock Register Values.
 *         The SystemCoreClock variable contains the core clock (HCLK), it can
 *         be used by the user application to setup the SysTick timer or
 * configure other parameters.
 *
 * @note   Each time the core clock (HCLK) changes, this function must be called
 *         to update SystemCoreClock variable value. Otherwise, any
 * configuration based on this variable will be incorrect.
 *
 * @note   - The system frequency computed by this function is not the real
 *           frequency in the chip. It is calculated based on the predefined
 *           constant and the selected clock source:
 *
 *           - If SYSCLK source is HSI, SystemCoreClock will contain the
 * HSI_VALUE(*)
 *
 *           - If SYSCLK source is HSE, SystemCoreClock will contain the
 * HSE_VALUE(**)
 *
 *           - If SYSCLK source is PLL, SystemCoreClock will contain the
 * HSE_VALUE(**) or HSI_VALUE(*) multiplied by the PLL factors.
 *
 *         (*) HSI_VALUE is a constant defined in n32g45x.h file (default value
 *             8 MHz) but the real value may vary depending on the variations
 *             in voltage and temperature.
 *
 *         (**) HSE_VALUE is a constant defined in N32G45X.h file (default value
 *              8 MHz or 25 MHz, depedning on the product used), user has to
 * ensure that HSE_VALUE is same as the real frequency of the crystal used.
 *              Otherwise, this function may have wrong result.
 *
 *         - The result of this function could be not correct when using
 * fractional value for HSE crystal.
 */
void SystemCoreClockUpdate(void)
{
    uint32_t tmp = 0, pllmull = 0, pllsource = 0;

    /* Get SYSCLK source
     * -------------------------------------------------------*/
    tmp = RCC->CFG & RCC_CFG_SCLKSTS;

    switch (tmp)
    {
    case 0x00: /* HSI used as system clock */
        SystemCoreClock = HSI_VALUE;
        break;
    case 0x04: /* HSE used as system clock */
        SystemCoreClock = HSE_VALUE;
        break;
    case 0x08: /* PLL used as system clock */

        /* Get PLL clock source and multiplication factor
         * ----------------------*/
        pllmull   = RCC->CFG & RCC_CFG_PLLMULFCT;
        pllsource = RCC->CFG & RCC_CFG_PLLSRC;

        if ((pllmull & RCC_CFG_PLLMULFCT_4) == 0)
        {
            pllmull = (pllmull >> 18) + 2; // PLLMUL[4]=0
        }
        else
        {
            pllmull = ((pllmull >> 18) - 496) + 1; // PLLMUL[4]=1
        }

        if (pllsource == 0x00)
        {
            /* HSI oscillator clock divided by 2 selected as PLL clock entry */
            SystemCoreClock = (HSI_VALUE >> 1) * pllmull;
        }
        else
        {
            /* HSE selected as PLL clock entry */
            if ((RCC->CFG & RCC_CFG_PLLHSEPRES) != (uint32_t)RESET)
            { /* HSE oscillator clock divided by 2 */
                SystemCoreClock = (HSE_VALUE >> 1) * pllmull;
            }
            else
            {
                SystemCoreClock = HSE_VALUE * pllmull;
            }
        }

        break;

    default:
        SystemCoreClock = HSI_VALUE;
        break;
    }

    /* Compute HCLK clock frequency ----------------*/
    /* Get HCLK prescaler */
    tmp = AHBPrescTable[((RCC->CFG & RCC_CFG_AHBPRES) >> 4)];
    /* HCLK clock frequency */
    SystemCoreClock >>= tmp;
}

/**
 * @brief  Configures the System clock frequency, HCLK, PCLK2 and PCLK1
 * prescalers.
 */
static void SetSysClock(void)
{
    uint32_t rcc_cfgr       = 0;
    bool HSEStatus          = 0;
    uint32_t StartUpCounter = 0;

#if SYSCLK_SRC == SYSCLK_USE_HSE || SYSCLK_SRC == SYSCLK_USE_HSE_PLL

    /* Enable HSE */
    RCC->CTRL |= ((uint32_t)RCC_CTRL_HSEEN);

    /* Wait till HSE is ready and if Time out is reached exit */
    do
    {
        HSEStatus = RCC->CTRL & RCC_CTRL_HSERDF;
        StartUpCounter++;
    } while ((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

    HSEStatus = ((RCC->CTRL & RCC_CTRL_HSERDF) != RESET);
    if (!HSEStatus)
    {
        /* If HSE fails to start-up, the application will have wrong clock
         * configuration. User can add here some code to deal with this error */
        SystemCoreClock = HSI_VALUE;
        return;
    }
#endif

    /* Flash wait state
        0: HCLK <= 32M
        1: HCLK <= 64M
        2: HCLK <= 96M
        3: HCLK <= 128M
        4: HCLK <= 144M
     */
    FLASH->AC &= (uint32_t)((uint32_t)~FLASH_AC_LATENCY);
    FLASH->AC |= (uint32_t)((SYSCLK_FREQ - 1) / 32000000);

    /* HCLK = SYSCLK */
    RCC->CFG |= (uint32_t)RCC_CFG_AHBPRES_DIV1;

    /* PCLK2 max 72M */
    if (SYSCLK_FREQ > 72000000)
    {
        RCC->CFG |= (uint32_t)RCC_CFG_APB2PRES_DIV2;
    }
    else
    {
        RCC->CFG |= (uint32_t)RCC_CFG_APB2PRES_DIV1;
    }

    /* PCLK1 max 36M */
    if (SYSCLK_FREQ > 72000000)
    {
        RCC->CFG |= (uint32_t)RCC_CFG_APB1PRES_DIV4;
    }
    else if (SYSCLK_FREQ > 36000000)
    {
        RCC->CFG |= (uint32_t)RCC_CFG_APB1PRES_DIV2;
    }
    else
    {
        RCC->CFG |= (uint32_t)RCC_CFG_APB1PRES_DIV1;
    }

#if SYSCLK_SRC == SYSCLK_USE_HSE
    /* Select HSE as system clock source */
    RCC->CFG &= (uint32_t)((uint32_t) ~(RCC_CFG_SCLKSW));
    RCC->CFG |= (uint32_t)RCC_CFG_SCLKSW_HSE;

    /* Wait till HSE is used as system clock source */
    while ((RCC->CFG & (uint32_t)RCC_CFG_SCLKSTS) != (uint32_t)0x04)
    {
    }
#elif SYSCLK_SRC == SYSCLK_USE_HSI_PLL || SYSCLK_SRC == SYSCLK_USE_HSE_PLL

    /* clear bits */
    RCC->CFG &= (uint32_t)((uint32_t) ~(RCC_CFG_PLLSRC | RCC_CFG_PLLHSEPRES | RCC_CFG_PLLMULFCT));

    /* set PLL source */
    rcc_cfgr = RCC->CFG;
    rcc_cfgr |= (SYSCLK_SRC == SYSCLK_USE_HSI_PLL ? RCC_CFG_PLLSRC_HSI_DIV2 : RCC_CFG_PLLSRC_HSE);

#if SYSCLK_SRC == SYSCLK_USE_HSE_PLL
    rcc_cfgr |= (PLLSRC_DIV == 1 ? RCC_CFG_PLLHSEPRES_HSE : RCC_CFG_PLLHSEPRES_HSE_DIV2);
#endif

    /* set PLL multiply factor */
#if PLL_MUL <= 16
    rcc_cfgr |= (PLL_MUL - 2) << 18;
#else
    rcc_cfgr |= ((PLL_MUL - 17) << 18) | (1 << 27);
#endif

    RCC->CFG = rcc_cfgr;

    /* Enable PLL */
    RCC->CTRL |= RCC_CTRL_PLLEN;

    /* Wait till PLL is ready */
    while ((RCC->CTRL & RCC_CTRL_PLLRDF) == 0)
    {
    }

    /* Select PLL as system clock source */
    RCC->CFG &= (uint32_t)((uint32_t) ~(RCC_CFG_SCLKSW));
    RCC->CFG |= (uint32_t)RCC_CFG_SCLKSW_PLL;

    /* Wait till PLL is used as system clock source */
    while ((RCC->CFG & (uint32_t)RCC_CFG_SCLKSTS) != (uint32_t)0x08)
    {
    }
#endif
}