//-------------------------------------------------------------------------*
// 文件名:sysinit.c                                                        *
// 說  明: 系統配置文件                                                    *
//-------------------------------------------------------------------------*

#include "sysinit.h"	//頭文件

//全局變量聲明
int core_clk_khz;
int core_clk_mhz;
int periph_clk_khz;

//-------------------------------------------------------------------------*
//函數名: sysinit                                                          *
//功  能: 系統設置                                                         * 
//參  數: 無						  	           *	
//返  回: 無                                                               *
//說  明: 無                                                               *
//-------------------------------------------------------------------------*
void sysinit (void)
{
    //使能IO端口時鐘    
    SIM_SCGC5 |= (SIM_SCGC5_PORTA_MASK
                              | SIM_SCGC5_PORTB_MASK
                              | SIM_SCGC5_PORTC_MASK
                              | SIM_SCGC5_PORTD_MASK
                              | SIM_SCGC5_PORTE_MASK );

    //開啟系統時鐘
    core_clk_mhz = pll_init(CORE_CLK_MHZ, REF_CLK);
    //通過pll_init函數的返回值來計算內核時鐘和外設時鐘
    core_clk_khz = core_clk_mhz * 1000;
    periph_clk_khz = core_clk_khz / (((SIM_CLKDIV1 & SIM_CLKDIV1_OUTDIV2_MASK) >> 24)+ 1);
    //使能跟蹤時鐘，用于調試
    trace_clk_init();	
    //FlexBus時鐘初始化
    fb_clk_init();

}

//-------------------------------------------------------------------------*
//函數名: trace_clk_init                                                   *
//功  能: 跟蹤時鐘初始化                                                   * 
//參  數: 無							  	   *	
//返  回: 無                                                               *
//說  明: 用于調試                                                         *
//-------------------------------------------------------------------------*
void trace_clk_init(void)
{
    //設置跟蹤時鐘為內核時鐘
    SIM_SOPT2 |= SIM_SOPT2_TRACECLKSEL_MASK;	
    //在PTA6引腳上使能TRACE_CLKOU功能
    PORTA_PCR6 = ( PORT_PCR_MUX(0x7));
}

//-------------------------------------------------------------------------*
//函數名: fb_clk_init                                                      *
//功  能: FlexBus時鐘初始化                                                * 
//參  數: 無								   *	
//返  回: 無                                                               *
//說  明:                                                                  *
//-------------------------------------------------------------------------*
void fb_clk_init(void)
{
    //使能FlexBus模塊時鐘
    SIM_SCGC7 |= SIM_SCGC7_FLEXBUS_MASK;
    //在PTA6引腳上使能FB_CLKOUT功能
    PORTC_PCR3 = ( PORT_PCR_MUX(0x5));
}

//-------------------------------------------------------------------------*
//函數名: pll_init                                                         *
//功  能: pll初始化                                                        * 
//參  數: clk_option:時鐘選項						   * 
//		  crystal_val:時鐘值                                       *	
//返  回: 時鐘頻率值                                                       *
//說  明:                                                                  *
//-------------------------------------------------------------------------*
unsigned char pll_init(unsigned char clk_option, unsigned char crystal_val)
{
    unsigned char pll_freq;
    
    if (clk_option > 3) {return 0;}   //如果沒有選擇可用的選項則返回0
    if (crystal_val > 15) {return 1;} // 如果如果可用的晶體選項不可用則返回1
    
    //這里處在默認的FEI模式
    //首先移動到FBE模式
    #if (defined(K60_CLK) || defined(ASB817))
             MCG_C2 = 0;
    #else
             //使能外部晶振
             MCG_C2 = MCG_C2_RANGE(2) | MCG_C2_HGO_MASK | MCG_C2_EREFS_MASK;
    #endif
    
    //初始化晶振后釋放鎖定狀態的振蕩器和GPIO
    SIM_SCGC4 |= SIM_SCGC4_LLWU_MASK;
    LLWU_CS |= LLWU_CS_ACKISO_MASK;
    
    //選擇外部晶振，參考分頻器，清IREFS來啟動外部晶振
    MCG_C1 = MCG_C1_CLKS(2) | MCG_C1_FRDIV(3);
    
    //等待晶振穩定	
    #if (!defined(K60_CLK) && !defined(ASB817))
    while (!(MCG_S & MCG_S_OSCINIT_MASK)){};  
    #endif
    
    //等待參考時鐘狀態位清零
    while (MCG_S & MCG_S_IREFST_MASK){}; 
    //等待時鐘狀態位顯示時鐘源來自外部參考時鐘
    while (((MCG_S & MCG_S_CLKST_MASK) >> MCG_S_CLKST_SHIFT) != 0x2){}; 
    
    //進入FBE模式
    #if (defined(K60_CLK))
    MCG_C5 = MCG_C5_PRDIV(0x18);
    #else
    
    //配置PLL分頻器來匹配所用的晶振
    MCG_C5 = MCG_C5_PRDIV(crystal_val); 
    #endif
    
    //確保MCG_C6處于復位狀態，禁止LOLIE、PLL、和時鐘控制器，清PLL VCO分頻器
    MCG_C6 = 0x0;
    //選擇PLL VCO分頻器，系統時鐘分頻器取決于時鐘選項
    switch (clk_option) {
    case 0:
      //設置系統分頻器
      //MCG=PLL, core = MCG, bus = MCG, FlexBus = MCG, Flash clock= MCG/2
      set_sys_dividers(0,0,0,1);
      //設置VCO分頻器，使能PLL為50MHz, LOLIE=0, PLLS=1, CME=0, VDIV=1
      MCG_C6 = MCG_C6_PLLS_MASK | MCG_C6_VDIV(1); //VDIV = 1 (x25)
      pll_freq = 50;
      break;
    case 1:
      //設置系統分頻器
      //MCG=PLL, core = MCG, bus = MCG/2, FlexBus = MCG/2, Flash clock= MCG/4
      set_sys_dividers(0,1,1,3);
      //設置VCO分頻器，使能PLL為100MHz, LOLIE=0, PLLS=1, CME=0, VDIV=26
      MCG_C6 = MCG_C6_PLLS_MASK | MCG_C6_VDIV(26); //VDIV = 26 (x50)
      pll_freq = 100;
      break;
    case 2:
      //設置系統分頻器
      //MCG=PLL, core = MCG, bus = MCG/2, FlexBus = MCG/2, Flash clock= MCG/4
      set_sys_dividers(0,1,1,3);
      //設置VCO分頻器，使能PLL為96MHz, LOLIE=0, PLLS=1, CME=0, VDIV=24
      MCG_C6 = MCG_C6_PLLS_MASK | MCG_C6_VDIV(24); //VDIV = 24 (x48)
      pll_freq = 96;
      break;
    case 3:
      //設置系統分頻器
      //MCG=PLL, core = MCG, bus = MCG, FlexBus = MCG, Flash clock= MCG/2
      set_sys_dividers(0,0,0,1);
      //設置VCO分頻器，使能PLL為48MHz, LOLIE=0, PLLS=1, CME=0, VDIV=0
      MCG_C6 = MCG_C6_PLLS_MASK; //VDIV = 0 (x24)
      pll_freq = 48;
      break;
    }
    while (!(MCG_S & MCG_S_PLLST_MASK)){}; // wait for PLL status bit to set
    
    while (!(MCG_S & MCG_S_LOCK_MASK)){}; // Wait for LOCK bit to set
    
    //進入PBE模式
    
    //通過清零CLKS位來進入PEE模式
    // CLKS=0, FRDIV=3, IREFS=0, IRCLKEN=0, IREFSTEN=0
    MCG_C1 &= ~MCG_C1_CLKS_MASK;
    
    //等待時鐘狀態位更新
    while (((MCG_S & MCG_S_CLKST_MASK) >> MCG_S_CLKST_SHIFT) != 0x3){};
    
    //開始進入PEE模式
    
    return pll_freq;
}

//-------------------------------------------------------------------------*
//函數名: set_sys_dividers                                                 *
//功  能: 設置系系統分頻器                                                 * 
//參  數: 預分頻值   							   *	
//返  回: 無                                                               *
//說  明: 此函數必須放在RAM里執行，否則會產生錯誤e2448。當FLASH時鐘分頻改變* 
//        時，必須禁止FLASH的預取功能。在時鐘分頻改變之后，必須延時一小段時*
//	 間才可以從新使能預取功能。                                        * 
//-------------------------------------------------------------------------*
__ramfunc void set_sys_dividers(uint32 outdiv1, uint32 outdiv2, uint32 outdiv3, uint32 outdiv4)
{
    uint32 temp_reg;
    uint8 i;
    //保存FMC_PFAPR當前的值
    temp_reg = FMC_PFAPR;
    
    //通過M&PFD置位M0PFD來禁止預取功能
    FMC_PFAPR |= FMC_PFAPR_M7PFD_MASK | FMC_PFAPR_M6PFD_MASK | FMC_PFAPR_M5PFD_MASK
                     | FMC_PFAPR_M4PFD_MASK | FMC_PFAPR_M3PFD_MASK | FMC_PFAPR_M2PFD_MASK
                     | FMC_PFAPR_M1PFD_MASK | FMC_PFAPR_M0PFD_MASK;
    
    //給時鐘分頻器設置期望值  
    SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(outdiv1) | SIM_CLKDIV1_OUTDIV2(outdiv2) 
                      | SIM_CLKDIV1_OUTDIV3(outdiv3) | SIM_CLKDIV1_OUTDIV4(outdiv4);
    
    //等待分頻器改變
    for (i = 0 ; i < outdiv4 ; i++)
    {}
    
    //從新存FMC_PFAPR的原始值
    FMC_PFAPR = temp_reg; 
    
    return;
}