klipper/lib/cmsis-sam3x8e/source/system_sam3xa.c

/*! \file *********************************************************************
 *
 * \brief Provides the low-level initialization functions that called 
 * on chip startup.
 *
 * $asf_license$
 *
 * \par Purpose
 *
 * This file provides basic support for Cortex-M processor based 
 * microcontrollers.
 *
 * \author               Atmel Corporation: http://www.atmel.com \n
 *                       Support and FAQ: http://support.atmel.no/
 *
 ******************************************************************************/

#include "sam3xa.h"

/* @cond 0 */
/**INDENT-OFF**/
#ifdef __cplusplus
extern "C" {
#endif
/**INDENT-ON**/
/* @endcond */

/* Clock settings (84MHz) */
#define SYS_BOARD_OSCOUNT   (CKGR_MOR_MOSCXTST(0x8))
#define SYS_BOARD_PLLAR     (CKGR_PLLAR_ONE \
							| CKGR_PLLAR_MULA(0xdUL) \
							| CKGR_PLLAR_PLLACOUNT(0x3fUL) \
							| CKGR_PLLAR_DIVA(0x1UL))
#define SYS_BOARD_MCKR      (PMC_MCKR_PRES_CLK_2 | PMC_MCKR_CSS_PLLA_CLK)

/* Clock Definitions */
#define SYS_UTMIPLL     		(480000000UL)	/* UTMI PLL frequency */

#define SYS_CKGR_MOR_KEY_VALUE	CKGR_MOR_KEY(0x37) /* Key to unlock MOR register */

/* FIXME: should be generated by sock */
uint32_t SystemCoreClock = CHIP_FREQ_MAINCK_RC_4MHZ;

/**
 * \brief Setup the microcontroller system.
 * Initialize the System and update the SystemFrequency variable.
 */
void SystemInit(void)
{
	/* Set FWS according to SYS_BOARD_MCKR configuration */
	EFC0->EEFC_FMR = EEFC_FMR_FWS(4);
	EFC1->EEFC_FMR = EEFC_FMR_FWS(4);

	/* Initialize main oscillator */
	if (!(PMC->CKGR_MOR & CKGR_MOR_MOSCSEL)) {
		PMC->CKGR_MOR = SYS_CKGR_MOR_KEY_VALUE | SYS_BOARD_OSCOUNT | 
			                     CKGR_MOR_MOSCRCEN | CKGR_MOR_MOSCXTEN;
		while (!(PMC->PMC_SR & PMC_SR_MOSCXTS)) {
		}
	}

	/* Switch to 3-20MHz Xtal oscillator */
	PMC->CKGR_MOR = SYS_CKGR_MOR_KEY_VALUE | SYS_BOARD_OSCOUNT | 
	                           CKGR_MOR_MOSCRCEN | CKGR_MOR_MOSCXTEN | CKGR_MOR_MOSCSEL;

	while (!(PMC->PMC_SR & PMC_SR_MOSCSELS)) {
	}
 	PMC->PMC_MCKR = (PMC->PMC_MCKR & ~(uint32_t)PMC_MCKR_CSS_Msk) | 
		                     PMC_MCKR_CSS_MAIN_CLK;
	while (!(PMC->PMC_SR & PMC_SR_MCKRDY)) {
	}

	/* Initialize PLLA */
	PMC->CKGR_PLLAR = SYS_BOARD_PLLAR;
	while (!(PMC->PMC_SR & PMC_SR_LOCKA)) {
	}

	/* Switch to main clock */
	PMC->PMC_MCKR = (SYS_BOARD_MCKR & ~PMC_MCKR_CSS_Msk) | PMC_MCKR_CSS_MAIN_CLK;
	while (!(PMC->PMC_SR & PMC_SR_MCKRDY)) {
	}

	/* Switch to PLLA */
	PMC->PMC_MCKR = SYS_BOARD_MCKR;
	while (!(PMC->PMC_SR & PMC_SR_MCKRDY)) {
	}

	SystemCoreClock = CHIP_FREQ_CPU_MAX;
}

void SystemCoreClockUpdate(void)
{
	/* Determine clock frequency according to clock register values */
	switch (PMC->PMC_MCKR & PMC_MCKR_CSS_Msk) {
	case PMC_MCKR_CSS_SLOW_CLK:	/* Slow clock */
		if (SUPC->SUPC_SR & SUPC_SR_OSCSEL) {
			SystemCoreClock = CHIP_FREQ_XTAL_32K;
		} else {
			SystemCoreClock = CHIP_FREQ_SLCK_RC;
		}
		break;
	case PMC_MCKR_CSS_MAIN_CLK:	/* Main clock */
		if (PMC->CKGR_MOR & CKGR_MOR_MOSCSEL) {
			SystemCoreClock = CHIP_FREQ_XTAL_12M;
		} else {
			SystemCoreClock = CHIP_FREQ_MAINCK_RC_4MHZ;

			switch (PMC->CKGR_MOR & CKGR_MOR_MOSCRCF_Msk) {
			case CKGR_MOR_MOSCRCF_4_MHz:
				break;
			case CKGR_MOR_MOSCRCF_8_MHz:
				SystemCoreClock *= 2U;
				break;
			case CKGR_MOR_MOSCRCF_12_MHz:
				SystemCoreClock *= 3U;
				break;
			default:
				break;
			}
		}
		break;
	case PMC_MCKR_CSS_PLLA_CLK:	/* PLLA clock */
	case PMC_MCKR_CSS_UPLL_CLK:	/* UPLL clock */
		if (PMC->CKGR_MOR & CKGR_MOR_MOSCSEL) {
			SystemCoreClock = CHIP_FREQ_XTAL_12M;
		} else {
			SystemCoreClock = CHIP_FREQ_MAINCK_RC_4MHZ;

			switch (PMC->CKGR_MOR & CKGR_MOR_MOSCRCF_Msk) {
			case CKGR_MOR_MOSCRCF_4_MHz:
				break;
			case CKGR_MOR_MOSCRCF_8_MHz:
				SystemCoreClock *= 2U;
				break;
			case CKGR_MOR_MOSCRCF_12_MHz:
				SystemCoreClock *= 3U;
				break;
			default:
				break;
			}
		}
		if ((PMC->PMC_MCKR & PMC_MCKR_CSS_Msk) == PMC_MCKR_CSS_PLLA_CLK) {
			SystemCoreClock *= ((((PMC->CKGR_PLLAR) & CKGR_PLLAR_MULA_Msk) >> 
				                            CKGR_PLLAR_MULA_Pos) + 1U);
			SystemCoreClock /= ((((PMC->CKGR_PLLAR) & CKGR_PLLAR_DIVA_Msk) >> 
				                             CKGR_PLLAR_DIVA_Pos));
		} else {
			SystemCoreClock = SYS_UTMIPLL / 2U;
		}
		break;
	}

	if ((PMC->PMC_MCKR & PMC_MCKR_PRES_Msk) == PMC_MCKR_PRES_CLK_3) {
		SystemCoreClock /= 3U;
	} else {
		SystemCoreClock >>= ((PMC->PMC_MCKR & PMC_MCKR_PRES_Msk) >> 
			                          PMC_MCKR_PRES_Pos);
	}
}

/** 
 * Initialize flash.
 */
void system_init_flash(uint32_t dw_clk)
{
	/* Set FWS for embedded Flash access according to operating frequency */
	if (dw_clk < CHIP_FREQ_FWS_0) {
		EFC0->EEFC_FMR = EEFC_FMR_FWS(0);
		EFC1->EEFC_FMR = EEFC_FMR_FWS(0);
	} else if (dw_clk < CHIP_FREQ_FWS_1) {
		EFC0->EEFC_FMR = EEFC_FMR_FWS(1);
		EFC1->EEFC_FMR = EEFC_FMR_FWS(1);
	} else if (dw_clk < CHIP_FREQ_FWS_2) {
		EFC0->EEFC_FMR = EEFC_FMR_FWS(2);
		EFC1->EEFC_FMR = EEFC_FMR_FWS(2);
	} else if (dw_clk < CHIP_FREQ_FWS_3) {
		EFC0->EEFC_FMR = EEFC_FMR_FWS(3);
		EFC1->EEFC_FMR = EEFC_FMR_FWS(3);
	} else {
		EFC0->EEFC_FMR = EEFC_FMR_FWS(4);
		EFC1->EEFC_FMR = EEFC_FMR_FWS(4);
	}
}

/* @cond 0 */
/**INDENT-OFF**/
#ifdef __cplusplus
}
#endif
/**INDENT-ON**/
/* @endcond */