/**************************************************************************
* NAME: system_clock.c                                                    *
* PURPOSE: Enable and handle system clock functionality                   *
* INFORMATION:                                                            *
*                                                                         *
* GLOBAL VARIABLES:                                                       *
* Variable        Type          Description                               *
* --------        ----          -----------                               *
**************************************************************************/

#include "drivers/system_clock.h"

//the number of clock cycles per microsecond
static uint32_t usTicks = 0;

/***********************************************************************
* BRIEF: Starts the system clock at 100MHz                             *
* INFORMATION: In the current version it works with ADC and DMA        *
***********************************************************************/
void system_clock_config(void)
{
	RCC_ClkInitTypeDef RCC_ClkInitStruct;
	RCC_OscInitTypeDef RCC_OscInitStruct;

	//Enable GPIO clocks
	__HAL_RCC_GPIOA_CLK_ENABLE();
	__HAL_RCC_GPIOB_CLK_ENABLE();
	__HAL_RCC_GPIOC_CLK_ENABLE();

	//Enable power clock
	__HAL_RCC_PWR_CLK_ENABLE();

	__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);

	RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
	RCC_OscInitStruct.HSEState = RCC_HSE_ON;
	RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
	RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
	RCC_OscInitStruct.PLL.PLLM = 8;
	RCC_OscInitStruct.PLL.PLLN = 288;
	RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
	RCC_OscInitStruct.PLL.PLLQ = 6;
	HAL_RCC_OscConfig(&RCC_OscInitStruct);

	RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
	RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
	RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
	RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
	RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
	HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_4);


	if (HAL_GetREVID() == 0x1001)
		__HAL_FLASH_PREFETCH_BUFFER_ENABLE();

	//Set the number of sycles per microsecond
	usTicks = SystemCoreClock / 1000000;

}

/***********************************************************************
* BRIEF: Get the time since the system started in microseconds
* INFORMATION: return the time in microseconds
***********************************************************************/
uint32_t clock_get_us()
{
	register uint32_t ms, cycle_cnt;

	//make sure that the system tick interrupt does not happen during the time we fetch microsecond from the register
	do {
		ms = clock_get_ms();
		cycle_cnt = SysTick->VAL;

		 //If the SysTick timer expired during the previous instruction, we need to give it a little time for that
		 //interrupt to be delivered before we can recheck sysTickUptime:
		asm volatile("\tnop\n");
	} while (ms != clock_get_ms());

	assert_param(us >= 1000);

	return (ms * 1000) + (usTicks * 1000 - cycle_cnt) / usTicks;
}

/***********************************************************************
* BRIEF: Get the time since the system started in milliseconds
* INFORMATION: return the time in milliseconds
***********************************************************************/
uint32_t clock_get_ms()
{
	return HAL_GetTick();
}

/***********************************************************************
* BRIEF: stall the system for number of milliseconds
* INFORMATION:
***********************************************************************/
void clock_delay_ms(uint32_t ms)
{
	HAL_Delay(ms);
}

/***********************************************************************
* BRIEF: Stall the system for a number of microseconds
* INFORMATION:
***********************************************************************/
void clock_delay_us(uint32_t us)
{
	volatile uint32_t time = clock_get_us() + us;
	while(clock_get_us() < time);
}