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esp_timer.c
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esp_timer.c
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/* Timer peripheral management functions for esp/timer.h.
*
*
* Part of esp-open-rtos
* Copyright (C) 2015 Superhouse Automation Pty Ltd
* BSD Licensed as described in the file LICENSE
*/
#include <esp/timer.h>
#include <esp/dport_regs.h>
#include <stdio.h>
#include <stdlib.h>
/* Timer divisor number to maximum frequency */
#define _FREQ_DIV1 (80*1000*1000)
#define _FREQ_DIV16 (5*1000*1000)
#define _FREQ_DIV256 312500
const static uint32_t IROM _TIMER_FREQS[] = { _FREQ_DIV1, _FREQ_DIV16, _FREQ_DIV256 };
/* Timer divisor index to divisor value */
const static uint32_t IROM _TIMER_DIV_VAL[] = { 1, 16, 256 };
void timer_set_interrupts(const timer_frc_t frc, bool enable)
{
const uint32_t dp_bit = (frc == FRC1) ? DPORT_INT_ENABLE_FRC1 : DPORT_INT_ENABLE_FRC2;
const uint32_t int_mask = BIT((frc == FRC1) ? INUM_TIMER_FRC1 : INUM_TIMER_FRC2);
if(enable) {
DPORT.INT_ENABLE |= dp_bit;
_xt_isr_unmask(int_mask);
} else {
DPORT.INT_ENABLE &= ~dp_bit;
_xt_isr_mask(int_mask);
}
}
uint32_t timer_freq_to_count(const timer_frc_t frc, const uint32_t freq, const timer_clkdiv_t div)
{
if(div < TIMER_CLKDIV_1 || div > TIMER_CLKDIV_256)
return 0; /* invalid divider */
if(freq > _TIMER_FREQS[div])
return 0; /* out of range for given divisor */
uint64_t counts = _TIMER_FREQS[div]/freq;
return counts;
}
uint32_t timer_time_to_count(const timer_frc_t frc, uint32_t us, const timer_clkdiv_t div)
{
if(div < TIMER_CLKDIV_1 || div > TIMER_CLKDIV_256)
return 0; /* invalid divider */
const uint32_t TIMER_MAX = timer_max_load(frc);
if(div != TIMER_CLKDIV_256) /* timer tick in MHz */
{
/* timer is either 80MHz or 5MHz, so either 80 or 5 MHz counts per us */
const uint32_t counts_per_us = ((div == TIMER_CLKDIV_1) ? _FREQ_DIV1 : _FREQ_DIV16)/1000/1000;
if(us > TIMER_MAX/counts_per_us)
return 0; /* Multiplying us by mhz_per_count will overflow TIMER_MAX */
return us*counts_per_us;
}
else /* /256 divider, 312.5kHz freq so need to scale up */
{
/* derived from naive floating point equation that we can't use:
counts = (us/1000/1000)*_FREQ_DIV256;
counts = (us/2000)*(_FREQ_DIV256/500);
counts = us*(_FREQ_DIV256/500)/2000;
*/
const uint32_t scalar = _FREQ_DIV256/500;
if(us > 1+UINT32_MAX/scalar)
return 0; /* Multiplying us by _FREQ_DIV256/500 will overflow uint32_t */
uint32_t counts = (us*scalar)/2000;
if(counts > TIMER_MAX)
return 0; /* counts value too high for timer type */
return counts;
}
}
int timer_set_frequency(const timer_frc_t frc, uint32_t freq)
{
uint32_t counts = 0;
timer_clkdiv_t div = timer_freq_to_div(freq);
if(freq == 0) //can't divide by 0
{
return -EINVAL;
}
counts = timer_freq_to_count(frc, freq, div);
if(counts == 0)
{
return -EINVAL;
}
timer_set_divider(frc, div);
if(frc == FRC1)
{
timer_set_load(frc, counts);
timer_set_reload(frc, true);
}
else /* FRC2 */
{
/* assume that if this overflows it'll wrap, so we'll get desired behaviour */
TIMER(1).ALARM = counts + TIMER(1).COUNT;
}
return 0;
}
int _timer_set_timeout_impl(const timer_frc_t frc, uint32_t us)
{
uint32_t counts = 0;
timer_clkdiv_t div = timer_time_to_div(us);
counts = timer_time_to_count(frc, us, div);
if(counts == 0)
return -EINVAL; /* can't set frequency */
timer_set_divider(frc, div);
if(frc == FRC1)
{
timer_set_load(frc, counts);
}
else /* FRC2 */
{
TIMER(1).ALARM = counts + TIMER(1).COUNT;
}
return 0;
}
int timer_set_timeout(const timer_frc_t frc, uint32_t us)
{
uint32_t counts = 0;
timer_clkdiv_t div = timer_time_to_div(us);
counts = timer_time_to_count(frc, us, div);
if(counts == 0)
return -EINVAL; /* can't set frequency */
timer_set_divider(frc, div);
if(frc == FRC1)
{
timer_set_load(frc, counts);
}
else /* FRC2 */
{
TIMER(1).ALARM = counts + TIMER(1).COUNT;
}
return 0;
}