init_lpc2.c

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#include <cpu/irq.h>
#include <drv/vic_lpc2.h>
#include <io/lpc23xx.h>

#if CPU_FREQ != 72000000UL
    /* Avoid errors on nightly test */
    #if !defined(ARCH_NIGHTTEST) || !(ARCH & ARCH_NIGHTTEST)
        #warning Clock registers set for 72MHz operation, revise following code if you want a different clock.
    #endif
#endif

/*
 * With a 12MHz cristal, master clock is:
 * (((2 * 12 * (PLL_MUL_VAL + 1)) / (PLL_DIV_VAL + 1)) / (LPC2_CPUCLOCK_DIV + 1))= 72MHz
 */
#define PLL_MUL_VAL  11
#define PLL_DIV_VAL  0
#define LPC2_CPUCLOCK_DIV 3


/* PLL feed sequence */
#define PLL_FEED_SEQ() ATOMIC(PLLFEED = 0xAA; PLLFEED = 0x55;)

static void configurePll(void)
{
    /* Disconnect and disable the PLL, if already active */
    if (PLLSTAT & (1 << 25))
    {
        /* Disconnect PLL, but leave it enabled */
        PLLCON = 0x01;
        PLL_FEED_SEQ();
        /* Disable PLL */
        PLLCON = 0;
        PLL_FEED_SEQ();
    }

    /* Enable the main oscillator and wait for it to be stable */
    SCS |= (1 << 5);
    while (!(SCS & (1 << 6))) ;

    /* Select the main oscillator as the PLL clock source */
    CLKSRCSEL = 0x01;

    /* Set up PLL mul and div */
    PLLCFG = PLL_MUL_VAL | (PLL_DIV_VAL << 16);
    PLL_FEED_SEQ();
    
    /* Enable PLL, disconnected */
    PLLCON = 0x01;
    PLL_FEED_SEQ();

    /* Set clock divider */
    CCLKCFG = LPC2_CPUCLOCK_DIV;

    /* Wait for the PLL to lock */
    while (!(PLLSTAT & (1 << 26))) ;
    
    /* Enable and connect the PLL */
    PLLCON = 0x03;
    PLL_FEED_SEQ();
}

void __init1(void);

void __init1(void)
{
    /* Map irq vectors to internal flash */
    MEMMAP = 0x01;
    /* Configure PLL, switch from IRC to Main OSC */
    configurePll();

    /* Set memory accelerator module flash timings */
#if CPU_FREQ < 20000000UL
    MAMTIM = 1;
#elif CPU_FREQ < 40000000UL
    MAMTIM = 2;
#elif CPU_FREQ < 60000000UL
    MAMTIM = 3;
#else
    MAMTIM = 4;
#endif
    
    /* Memory accelerator module fully enabled */
    MAMCR = 0x02;
}

void __init2(void);

void __init2(void)
{
    vic_init();
}