/*
	Initialisation functions for exception handlers, PLL and MAM
	
	Partially copied from Jim Lynch's tutorial
*/

/**********************************************************
                  Header files
 **********************************************************/

#include "startup.h"

#define MAMCR		*(volatile unsigned int *)0xE01FC000
#define MAMTIM		*(volatile unsigned int *)0xE01FC004

#define PLLCON		*(volatile unsigned int *)0xE01FC080
#define PLLCFG		*(volatile unsigned int *)0xE01FC084
#define PLLSTAT		*(volatile unsigned int *)0xE01FC088
#define PLLFEED		*(volatile unsigned int *)0xE01FC08C

#define VPBDIV		*(volatile unsigned int *)0xE01FC100
void IRQ_Routine(void) __attribute__ ((interrupt("IRQ")));
void FIQ_Routine(void) __attribute__ ((interrupt("FIQ")));
void SWI_Routine(void) __attribute__ ((interrupt("SWI")));
void UNDEF_Routine(void) __attribute__ ((interrupt("UNDEF")));

/*  Stubs for various interrupts (may be replaced later)  */
/*  ----------------------------------------------------  */
void IRQ_Routine(void)
{
    while (1);
}
void FIQ_Routine(void)
{
    while (1);
}
void SWI_Routine(void)
{
    while (1);
}
void UNDEF_Routine(void)
{
    while (1);
}


/**********************************************************
                      Initialize
**********************************************************/

#define PLOCK 0x400
static void feed(void)
{
    PLLFEED = 0xAA;
    PLLFEED = 0x55;
} void Initialize(void)
{

    //                              Setting the Phased Lock Loop (PLL)
    //               ----------------------------------
    //
    // Olimex LPC-P2148 has a 12.0000 mhz crystal
    //
    // We'd like the LPC2148 to run at 60 mhz (has to be an even multiple of crystal)
    // 
    // According to the Philips LPC2148 manual:   M = cclk / Fosc   where:  M    = PLL multiplier (bits 0-4 of PLLCFG)
    //                                                                                                                                              cclk = 60000000 hz
    //                                                                                                                                              Fosc = 12000000 hz
    //
    // Solving:     M = 60000000 / 12000000 = 5           
    //
    //                      Note: M - 1 must be entered into bits 0-4 of PLLCFG (assign 4 to these bits)
    //
    //
    // The Current Controlled Oscilator (CCO) must operate in the range 156 mhz to 320 mhz
    //
    // According to the Philips LPC2148 manual:     Fcco = cclk * 2 * P    where:   Fcco = CCO frequency 
    //                                                                                                                                                      cclk = 60000000 hz
    //                                                                                                                                                      P = PLL divisor (bits 5-6 of PLLCFG)
    //
    // Solving:     Fcco = 60000000 * 2 * P
    //                      P = 2  (trial value)
    //                      Fcco = 60000000 * 2 * 2
    //                      Fcc0 = 240000000 hz    (good choice for P since it's within the 156 mhz to 320 mhz range)
    //
    // From Table 22 (page 34) of Philips LPC2148 manual    P = 2, PLLCFG bits 5-6 = 1  (assign 1 to these bits)
    //
    // Finally:      PLLCFG = 0  01  00100  =  0x24
    //
    // Final note: to load PLLCFG register, we must use the 0xAA followed 0x55 write sequence to the PLLFEED register
    //             this is done in the short function feed() below
    //

    // Setting Multiplier and Divider values
    PLLCFG = 0x24;
    feed();

    // Enabling the PLL */  
    PLLCON = 0x1;
    feed();

    // Wait for the PLL to lock to set frequency
    while (!(PLLSTAT & PLOCK));

    // Connect the PLL as the clock source
    PLLCON = 0x3;
    feed();

    // Enabling MAM and setting number of clocks used for Flash memory fetch
    MAMTIM = 0x3;
    MAMCR = 0x2;

    // Setting peripheral Clock (pclk) to System Clock (cclk)
    VPBDIV = 0x1;
}