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

static uint32_t master_clock = 0;

/** Use TIM4_CH4, which is linked to PD15 AF1 **/
int pwm_init(uint32_t clock, uint32_t threshold)
{
    uint32_t val = (clock / 100000); /* Frequency is 100 KHz */
    uint32_t lvl;
    master_clock = clock;

    if (threshold > 100)
        return -1;

    lvl = (val * threshold) / 100;
    if (lvl != 0)
        lvl--;
    
    APB1_CLOCK_RST |= TIM4_APB1_CLOCK_ER_VAL;
    __asm__ volatile ("dmb");
    APB1_CLOCK_RST &= ~TIM4_APB1_CLOCK_ER_VAL;
    APB1_CLOCK_ER |= TIM4_APB1_CLOCK_ER_VAL;

    /* disable CC */
    TIM4_CCER  &= ~TIM_CCER_CC4_ENABLE;
    TIM4_CR1    = 0;
    TIM4_PSC    = 0;
    TIM4_ARR    = val - 1;
    TIM4_CCR4   = lvl;
    TIM4_CCMR1  &= ~(0x03 << 0);
    TIM4_CCMR1  &= ~(0x07 << 4);
    TIM4_CCMR1  |= TIM_CCMR1_OC1M_PWM1;
    TIM4_CCMR2  &= ~(0x03 << 8);
    TIM4_CCMR2  &= ~(0x07 << 12);
    TIM4_CCMR2  |= TIM_CCMR2_OC4M_PWM1;
    TIM4_CCER  |= TIM_CCER_CC4_ENABLE;
    TIM4_CR1    |= TIM_CR1_CLOCK_ENABLE | TIM_CR1_ARPE;
    __asm__ volatile ("dmb");
    return 0;
}


/* Timer 2: Use val 60000 with PSC 1400 for 1s tick (84 Mhz) */
/* Timer 2: Use val 52500 with PSC 200 for 1/8 s tick (84 Mhz) */

#define TMR2_INIT_VAL 52500
#define TMR2_INIT_PSC 200

void timer_init(void)
{
    uint32_t val = 0;
    uint32_t psc = 1;
    uint32_t err = 0;

    nvic_irq_enable(NVIC_TIM2_IRQN);
    nvic_irq_setprio(NVIC_TIM2_IRQN, 0);
    APB1_CLOCK_RST |= TIM2_APB1_CLOCK_ER_VAL;
    __asm__ volatile ("dmb");
    APB1_CLOCK_RST &= ~TIM2_APB1_CLOCK_ER_VAL;
    APB1_CLOCK_ER |= TIM2_APB1_CLOCK_ER_VAL;

    TIM2_CR1    = 0;
    __asm__ volatile ("dmb");
    TIM2_PSC    = TMR2_INIT_PSC;
    TIM2_ARR    = TMR2_INIT_VAL;
    TIM2_CR1    |= TIM_CR1_CLOCK_ENABLE;
    TIM2_DIER   |= TIM_DIER_UIE;
    __asm__ volatile ("dmb");
}

static volatile uint32_t tim2_ticks = 0;
void isr_tim2(void) 
{
    TIM2_SR &= ~TIM_SR_UIF;
    tim2_ticks++;
}

void gettime(uint32_t *seconds, uint32_t *microseconds)
{
    *microseconds = ((TIM2_CNT * TMR2_INIT_PSC) / 84) + (tim2_ticks & 0x07) * 125000;
    *seconds = (tim2_ticks >> 3);
}