void platform_early_init(void)
{
/* set up clocking for a board with an external oscillator */
Chip_SetupXtalClocking();
/* Set USB PLL input to main oscillator */
Chip_Clock_SetUSBPLLSource(SYSCTL_PLLCLKSRC_MAINOSC);
/* Setup USB PLL (FCLKIN = 12MHz) * 4 = 48MHz
MSEL = 3 (this is pre-decremented), PSEL = 1 (for P = 2)
FCLKOUT = FCLKIN * (MSEL + 1) = 12MHz * 4 = 48MHz
FCCO = FCLKOUT * 2 * P = 48MHz * 2 * 2 = 192MHz (within FCCO range) */
Chip_Clock_SetupUSBPLL(3, 1);
/* Powerup USB PLL */
Chip_SYSCTL_PowerUp(SYSCTL_POWERDOWN_USBPLL_PD);
/* Wait for PLL to lock */
while (!Chip_Clock_IsUSBPLLLocked()) {}
/* Set default system tick divder to 1 */
Chip_Clock_SetSysTickClockDiv(1);
/* start the generic systick driver */
arm_cm_systick_init(Chip_Clock_GetMainClockRate());
lpc_debug_early_init();
}
void sam_timer_early_init(void)
{
#if 0
pmc_enable_periph_clk(ID_TC0);
uint32_t ul_div;
uint32_t ul_tcclks;
uint32_t ul_sysclk = MCLK; // sysclk_get_cpu_hz();
tc_find_mck_divisor(100, ul_sysclk, &ul_div, &ul_tcclks, ul_sysclk);
tc_init(TC0, 0, TC_CMR_TCCLKS_TIMER_CLOCK1 | TC_CMR_CPCTRG);
tc_write_rc(TC0, 0, (ul_sysclk / ul_div) / 4);
tc_find_mck_divisor(100, ul_sysclk, &ul_div, &ul_tcclks, ul_sysclk);
tc_init(TC0, 0, TC_CMR_TCCLKS_TIMER_CLOCK1 | TC_CMR_CPCTRG);
tc_write_rc(TC0, 0, 0xffff); // slowest we can run
/* Configure and enable interrupt on RC compare */
NVIC_SetPriority(ID_TC0, arm_cm_highest_priority());
NVIC_EnableIRQ((IRQn_Type) ID_TC0);
tc_enable_interrupt(TC0, 0, TC_IER_CPCS);
#endif
tc_start(TC0, 0);
arm_cm_systick_init(MCLK);
}
void platform_early_init(void)
{
// Do general system init
SystemInit();
SystemClock_Config();
// Enable the flash ART controller
__HAL_FLASH_ART_ENABLE();
__HAL_FLASH_PREFETCH_BUFFER_ENABLE();
/* read the unique id */
stm32_unique_id[0] = *REG32(0x1ff0f420);
stm32_unique_id[1] = *REG32(0x1ff0f424);
stm32_unique_id[2] = *REG32(0x1ff0f428);
/* seed the random number generator based on this */
srand(stm32_unique_id[0] ^ stm32_unique_id[1] ^ stm32_unique_id[2]);
// Start the systick timer
uint32_t sysclk = HAL_RCC_GetSysClockFreq();
arm_cm_systick_init(sysclk);
stm32_timer_early_init();
stm32_gpio_early_init();
stm32_flash_early_init();
stm32_rng_init();
/* clear the reboot reason */
RCC->CSR |= (1<<24);
// ITM_SendChar('1');
}
