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RIOT/cpu/stm32_common/periph/timer.c

184 lines
3.7 KiB
C

/*
* Copyright (C) 2014-2016 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser General
* Public License v2.1. See the file LICENSE in the top level directory for more
* details.
*/
/**
* @ingroup cpu_stm32_common
* @{
*
* @file
* @brief Low-level timer driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Thomas Eichinger <thomas.eichinger@fu-berlin.de>
*
* @}
*/
#include "cpu.h"
#include "periph/timer.h"
/**
* @brief Timer specific additional bus clock presacler
*
* This prescale factor is dependent on the actual APBx bus clock divider, if
* the APBx presacler is != 1, it is set to 2, if the APBx prescaler is == 1, it
* is set to 1.
*
* See reference manuals section 'reset and clock control'.
*/
static const uint8_t apbmul[] = {
#if (CLOCK_APB1 < CLOCK_CORECLOCK)
[APB1] = 2,
#else
[APB1] = 1,
#endif
#if (CLOCK_APB2 < CLOCK_CORECLOCK)
[APB2] = 2
#else
[APB2] = 1
#endif
};
/**
* @brief Interrupt context for each configured timer
*/
static timer_isr_ctx_t isr_ctx[TIMER_NUMOF];
/**
* @brief Get the timer device
*/
static inline TIM_TypeDef *dev(tim_t tim)
{
return timer_config[tim].dev;
}
int timer_init(tim_t tim, unsigned long freq, timer_cb_t cb, void *arg)
{
/* check if device is valid */
if (tim >= TIMER_NUMOF) {
return -1;
}
/* remember the interrupt context */
isr_ctx[tim].cb = cb;
isr_ctx[tim].arg = arg;
/* enable the peripheral clock */
periph_clk_en(timer_config[tim].bus, timer_config[tim].rcc_mask);
/* configure the timer as upcounter in continuous mode */
dev(tim)->CR1 = 0;
dev(tim)->CR2 = 0;
dev(tim)->ARR = timer_config[tim].max;
/* set prescaler */
dev(tim)->PSC = (((periph_apb_clk(timer_config[tim].bus) *
apbmul[timer_config[tim].bus]) / freq) - 1);
/* generate an update event to apply our configuration */
dev(tim)->EGR = TIM_EGR_UG;
/* enable the timer's interrupt */
NVIC_EnableIRQ(timer_config[tim].irqn);
/* reset the counter and start the timer */
timer_start(tim);
return 0;
}
int timer_set(tim_t tim, int channel, unsigned int timeout)
{
int now = timer_read(tim);
return timer_set_absolute(tim, channel, now + timeout);
}
int timer_set_absolute(tim_t tim, int channel, unsigned int value)
{
if (channel >= TIMER_CHAN) {
return -1;
}
dev(tim)->CCR[channel] = (value & timer_config[tim].max);
dev(tim)->SR &= ~(TIM_SR_CC1IF << channel);
dev(tim)->DIER |= (TIM_DIER_CC1IE << channel);
return 0;
}
int timer_clear(tim_t tim, int channel)
{
if (channel >= TIMER_CHAN) {
return -1;
}
dev(tim)->DIER &= ~(TIM_DIER_CC1IE << channel);
return 0;
}
unsigned int timer_read(tim_t tim)
{
return (unsigned int)dev(tim)->CNT;
}
void timer_start(tim_t tim)
{
dev(tim)->CR1 |= TIM_CR1_CEN;
}
void timer_stop(tim_t tim)
{
dev(tim)->CR1 &= ~(TIM_CR1_CEN);
}
static inline void irq_handler(tim_t tim)
{
uint32_t status = (dev(tim)->SR & dev(tim)->DIER);
for (unsigned int i = 0; i < TIMER_CHAN; i++) {
if (status & (TIM_SR_CC1IF << i)) {
dev(tim)->DIER &= ~(TIM_DIER_CC1IE << i);
isr_ctx[tim].cb(isr_ctx[tim].arg, i);
}
}
cortexm_isr_end();
}
#ifdef TIMER_0_ISR
void TIMER_0_ISR(void)
{
irq_handler(0);
}
#endif
#ifdef TIMER_1_ISR
void TIMER_1_ISR(void)
{
irq_handler(1);
}
#endif
#ifdef TIMER_2_ISR
void TIMER_2_ISR(void)
{
irq_handler(2);
}
#endif
#ifdef TIMER_3_ISR
void TIMER_3_ISR(void)
{
irq_handler(3);
}
#endif
#ifdef TIMER_4_ISR
void TIMER_4_ISR(void)
{
irq_handler(4);
}
#endif