/**
*
* @brief Initialize and enable the system clock
*
* This routine is used to program the systick to deliver interrupts at the
* rate specified via the 'sys_clock_us_per_tick' global variable.
*
* @return 0
*/
int _sys_clock_driver_init(struct device *device)
{
/* enable counter, interrupt and set clock src to system clock */
u32_t ctrl = SysTick_CTRL_ENABLE_Msk | SysTick_CTRL_TICKINT_Msk |
SysTick_CTRL_CLKSOURCE_Msk;
ARG_UNUSED(device);
/*
* Determine the reload value to achieve the configured tick rate.
*/
/* systick supports 24-bit H/W counter */
__ASSERT(sys_clock_hw_cycles_per_tick <= (1 << 24),
"sys_clock_hw_cycles_per_tick too large");
sysTickReloadSet(sys_clock_hw_cycles_per_tick - 1);
#ifdef CONFIG_TICKLESS_IDLE
/* calculate hardware-specific parameters for tickless idle */
sysTickTicklessIdleInit();
#endif /* CONFIG_TICKLESS_IDLE */
NVIC_SetPriority(SysTick_IRQn, _IRQ_PRIO_OFFSET);
SysTick->CTRL = ctrl;
SysTick->VAL = 0; /* triggers immediate reload of count */
return 0;
}
/**
*
* @brief Initialize and enable the system clock
*
* This routine is used to program the systick to deliver interrupts at the
* rate specified via the 'sys_clock_us_per_tick' global variable.
*
* @return 0
*/
int _sys_clock_driver_init(struct device *device)
{
/* enable counter, interrupt and set clock src to system clock */
union __stcsr stcsr = {.bit = {1, 1, 1, 0, 0, 0} };
ARG_UNUSED(device);
/*
* Determine the reload value to achieve the configured tick rate.
*/
/* systick supports 24-bit H/W counter */
__ASSERT(sys_clock_hw_cycles_per_tick <= (1 << 24),
"sys_clock_hw_cycles_per_tick too large");
sysTickReloadSet(sys_clock_hw_cycles_per_tick - 1);
#ifdef CONFIG_TICKLESS_IDLE
/* calculate hardware-specific parameters for tickless idle */
sysTickTicklessIdleInit();
#endif /* CONFIG_TICKLESS_IDLE */
_ScbExcPrioSet(_EXC_SYSTICK, _EXC_IRQ_DEFAULT_PRIO);
__scs.systick.stcsr.val = stcsr.val;
return 0;
}
